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Technical Information Session on
Nuclear Power Plant Technologies
Transcripts, Presentations, and Archived Webcast
May 7, 2009
May 7, 2009: Archived Webcast of the Technical Information Session about nuclear power plan designs to the Joint Review Panel English link: http://www.nuclearsafety.gc.ca/eng/readingroom/newbuilds/brucepower/webcast-joint-review-panel-technical-information-session-may-7-2009.cfm Le 7 mai 2009 : Archive de la webdiffusion de la séance d’information technique de la Commission d’examen conjoint concernant la conception des centrales nucléaires French link: http://www.nuclearsafety.gc.ca/fr/readingroom/newbuilds/brucepower/webcast-joint-review-panel-technical-information-session-may-7-2009.cfm
Joint Review Panel for the Commission d’examen conjoint proposed Bruce Power du projet de nouvelle centrale New Nuclear Plant Project nucléaire de Bruce Power Public meeting Réunion publique Technical Information Session Séance d’information technique on Nuclear Power Plant Designs au sujet de la conception de centrales
nucléaires May 7th, 2009 Le 7 mai 2009 Public Hearing Room Salle d’audiences publiques 14th floor 14e étage 280 Slater Street 280, rue Slater Ottawa, Ontario Ottawa (Ontario) Members present Commissaires présents Mr. Louis LaPierre M. Louis LaPierre Mr. André Harvey M. André Harvey Dr. Moyra McDil Mme Moyra McDill Co-Managers: Cogestionnaires : Ms. Kelly McGee Mme Kelly McGee Ms. Debra Myles Mme Debra Myles Senior Counsel: Avocat principal : Mr. Michael A. James M. Michael A. James
(ii) TABLE OF CONTENTS
PAGE Opening Remarks 1 1. Presentation of three technologies by CNSC staff 2 Technical Briefing on Reactor Technologies 4 Cooling Water System Technology and Associated Environmental Impacts 36 Radioactive Waste Management for new Builds 69 2. Questions from Joint Panel Members 75
1
Ottawa, Ontario 1
2
--- Upon commencing on Thursday, May 7, 2009 3
at 12:30 p.m. 4
5
Opening Remarks 6
7
MS. McGEE: Good afternoon. Bonjour, 8
mesdames et messieurs. Bienvenue à la réunion 9
publique de la Commission d’examen conjointe du projet 10
de nouvelle centrale nucléaire de Bruce Power. 11
Mon nom est Kelly McGee et je suis la 12
co-gestionnaire de la Commission d’examen conjoint et 13
j’aimerais aborder certains aspects touchant le 14
déroulement de la réunion d’aujourd’hui. 15
We have simultaneous translation. 16
Please keep the pace of your speech relatively slow so 17
that the translators have a chance to keep up. 18
Des appareils de traduction sont 19
disponibles à la réception. La version française est 20
au poste 8. The English version is on channel 7. 21
A transcript of today’s information 22
session will also be produced. Please identify 23
yourself before speaking so that the transcripts are 24
as complete and clear as possible. 25
2
Les transcriptions seront disponibles 1
sur le site web de la Commission et le site web de 2
l’Agence canadienne d’évaluation environnementale dès 3
la semaine prochaine. 4
In addition, please note that this 5
meeting is broadcasted live on webcast and that the 6
webcast is also archived for a period of three months 7
following the meeting. 8
Please silence your cell phones and 9
other electronic devices. 10
Monsieur LaPierre, président de la 11
Commission d’examen conjoint, va présider la réunion 12
publique d’aujourd’hui. 13
THE CHAIRMAN: Bonjour. Good 14
afternoon. 15
I think we will start with the first 16
presenter. 17
18
1. Presentation of three technologies by CNSC staff 19
20
MR. SCHWARZ: Good afternoon, Mr. 21
Chairman, Members of the Panel, ladies and gentlemen. 22
My name is Garry Schwarz and I am the Regulatory 23
Program Director of the New Major Facilities Licensing 24
Division. 25
3
I have with me Mr. David Newland, 1
Director of the Assessment Integration Division, Mr. 2
Malcolm McKee, Acting Director of the Environmental 3
Risk Assessment Division, and Mr. Don Howard, Director 4
of the Wastes and Decommissioning Division. 5
In addition, we have several CNSC 6
technical staff available to assist us in responding 7
to any questions that the Panel may have. 8
Now, in response to the Joint Review 9
Panel’s request of February the 24th, 2009, the CNSC 10
staff has prepared presentations on the following 11
topics relevant to Bruce Power’s Environmental Impact 12
Statement and amended application for a licence to 13
prepare its site of October the 10th, 2008. 14
First, we'll have a technical briefing 15
on the three reactor technologies presented in the 16
Bruce Power submissions and this presentation will be 17
made by Mr. Newland. 18
Secondly, we'll have a presentation on 19
condenser cooling water systems and their 20
environmental impacts. This presentation will be made 21
by Mr. McKee. 22
And, finally, we’ll have a presentation 23
on radioactive waste management for new builds and 24
this presentation will be made by Mr. Howard. 25
4
Now, the three presentations are going 1
to take approximately three-and-a-half hours to 2
complete, starting with the longest and ending with 3
the shortest. CNSC staff would be pleased to answer 4
any questions that the Panel may have, either at the 5
end of each presentation or after all the 6
presentations have been made. 7
Now, with your permission, I will now 8
turn the floor over to Mr. Newland who will give the 9
first presentation. 10
Mr. Newland. 11
12
Technical Briefing on Reactor Technologies 13
14
MR. NEWLAND: Thank you, Mr. Schwarz. 15
Good afternoon. My name is David 16
Newland. I am Director of the Assessment Integration 17
Division within the Directorate of Assessment and 18
Analysis. 19
Today, I will be presenting an overview 20
of the reactor technologies that have been presented 21
in the Environmental Impact Statement. 22
This is what we will be talking about 23
today. We'll give a purpose of the briefing and an 24
outline overview of the ACR-1000 design, then the EPR 25
5
design, and then the Westinghouse AP1000 design. And 1
as Mr. Schwarz indicated, we have two other 2
presentations that will be covering the cooling 3
technology options and waste management aspects. 4
The purpose of the briefing is to 5
provide the Panel with an overview of some aspects of 6
the three designs in the proponent’s project 7
description. 8
The briefing focuses on aspects that 9
are of relevance to the Environmental Impact 10
Statement. 11
Information will include: principal 12
features of the designs; key operational parameters; 13
normal operation; and control and mitigation of 14
potential accidents. 15
The three designs that we are 16
presenting are AECL’s ACR-1000 pressure tube reactor, 17
AREVA’s US EPR pressurised water reactor, and 18
Westinghouse’s AP1000 PWR, in that order. 19
Please note that the presentation will 20
be at a relatively high level and it is not our 21
intention to give a detailed description of each of 22
the designs. 23
Also, we will not compare these designs 24
other than in a very global way that draws out some of 25
6
the key similarities and differences. 1
I have with me some of the specialists 2
who have reviewed various aspects of these designs and 3
we will be prepared to answer questions at this high 4
level. 5
I apologize upfront for the number of 6
acronyms in the slides and I will try to ensure that I 7
define these as we go through the presentation. 8
Finally, I would like to acknowledge 9
the permission of the vendors, AECL, AREVA and 10
Westinghouse, to use their graphics and photographs. 11
So we will start with the ACR-1000. 12
The ACR-1000 is designed by Atomic 13
Energy of Canada Limited, AECL. The design is based 14
on the established CANDU horizontal pressure tube 15
concept. The design builds on proven engineering 16
concepts of the established CANDU technology, 17
incorporating feedback from ongoing operational 18
experience with the current fleet of CANDU reactors. 19
That being said, there are some key 20
differences which we will highlight during the 21
presentation. 22
It uses heavy water as the moderator 23
and light water as the coolant. The fuel is of the 24
CANFLEX 43 element fuel design. As with all CANDU 25
7
designs, the ACR-1000 incorporates online fuelling. 1
This slide presents some of the key 2
parameters. 3
The design produces a thermal power of 4
3,200 megawatts, which converts to approximately 1000 5
megawatts electrical. 6
There are 520 channels held 7
horizontally in a regular lattice within the calandria 8
vessel, which also holds the heavy water moderator. 9
The heat transport system uses light water. 10
The fuel is enriched with U235 up to 11
2.4 percent by weight. The operating pressure and 12
temperature are 11 megapascals and 310 Celsius, 13
respectively. 14
This is a more compact core than 15
previous CANDU designs due to the tighter lattice 16
pitch, 24 centimetres versus 28 centimetres, for what 17
I would refer to as “standard” CANDU technology. 18
In addition, the heat transport system 19
uses light water which is different than for the 20
existing fleet. 21
The design uses slightly enriched fuel 22
rather than the natural uranium fuel for the existing 23
CANDUs. 24
In addition and finally, the heat 25
8
transport system pressure and temperature are a little 1
higher than for the existing facilities. 2
At this point, I will take this 3
opportunity to remind you of the overall process by 4
which electricity is generated. 5
Although I use ACR as the example, the 6
general principles apply to all of the technologies 7
presented today. 8
The fission reaction in the fuel 9
produces heat which is transferred to the water pumped 10
through the closed primary circuit. This heat is 11
transferred to the secondary side in the steam 12
generators, which produce high quality steam, i.e. 13
very dry steam containing very little liquid. 14
That is then used to drive the high and 15
low pressure turbines which drive the generator to 16
produce the electricity. This electricity is directed 17
to the external electrical grid via transformers and 18
switchyard. 19
The subsequent low-quality steam is 20
then condensed and fed back to the secondary-side 21
inlets of the steam generators. The cooling water in 22
the condenser comes from the chosen cooling technology 23
that will be discussed today in a separate 24
presentation. 25
9
Just to comment, sort of briefly, on 1
the overall ACR-1000 design here, you can see on your 2
left and at the bottom, the calandria, and at each 3
face there is a schematic of a fuelling machine. To 4
the left and to the right and immediately above, you 5
see the feeders which go to headers and then you can 6
observe the four heat-transport system pumps and the 7
largest components which are the steam generators, and 8
all of those reside within the concrete containment. 9
Turning now to the specifics of the 10
ACR-1000 design, this figure illustrates an overview 11
of the overall heat transport system components and 12
structure. There are two heat transport loops; each 13
in a figure of eight configuration. Each loop has 260 14
fuel channels, two heat transport system pumps and two 15
steam generators. 16
The fluid flows through one pass of 17
fuel channels into the individual feeders to an outlet 18
header, then to a steam generator and a heat transport 19
pump, then back to an inlet header which distributes 20
the fluid into inlet feeders which then feed through a 21
second pass of fuels channels. The flow proceeds to 22
the second outlet header, second steam generator and 23
the second pump to complete the figure of eight loop. 24
There is a pressurizer attached to the 25
10
hot legs which is used to control the pressure of the 1
heat transport system. The pressurizer is marked in 2
blue on the left of the diagram. 3
The core consists of a calandria 4
structure through which there are 520 fuel channels. 5
The heavy water is contained within the calandria at 6
low pressure. THE ACR-1000 fuel channel assembly 7
consists of a zirconium-niobium pressure tube centred 8
in a zircaloy calandria tube. The pressure tube is 9
roll-expanded into stainless steel end fittings at 10
each end and each fuel channel contains 12 CANFLEX 11
fuel bundles. 12
At the bottom of the diagram, you will 13
also note the other components of the moderator 14
system; in sort of dark blue, the moderator pump and 15
the heat exchangers of which there are two of each. 16
And then, finally, you will note at each of the 17
reactor faces, there is a fuelling machine which 18
performs the on-line fuelling. 19
So now I’ll move to some graphics of 20
some specific parts of the systems. 21
This is an illustration of the CANFLEX 22
fuel bundle. There are 43 elements held in place with 23
end plates. You will note sort of on the outer 24
surfaces of the fuel elements themselves, there are 25
11
various appendages to improve the fluid flow and the 1
heat transfer capabilities of the bundle. 2
The centre element contains neutron 3
absorbers while the remaining elements contain U-235 4
enriched uranium dioxide pellets. The neutron 5
absorbers of the central element are used for the 6
management of coolant void reactivity 7
This is another illustration of the ACR 8
reactant assembly showing the calandria vessel which 9
is contained within a calandria vault. Note at the 10
top, sitting on top of the calandria vault, the 11
reactivity mechanism deck and the location of shutdown 12
system 1 shutoff rods which are poised for insertion 13
immediately above the core. 14
Note also, marked on the diagram as 15
LISS injection, these are the poison injection units 16
for shutdown system number 2. 17
I will briefly discuss the ACR-1000 18
four-quadrant approach. There are safety and safety 19
support systems including single, duplicated or 20
quadruplicated divisions to satisfy operational and 21
safety considerations. 22
For single or two-division systems, 23
adequate redundancy is provided within each division 24
to ensure that availability targets can be met in 25
12
order to satisfy operational and safety performance 1
requirements. 2
Selected four-division systems achieve 3
optimum safety and operation performance and 4
reliability. The four-division systems are aligned 5
with the four-quadrant layout approach for which there 6
is a diagram later. Inter-ties between divisions are 7
provided as required to further enhance reliability 8
and operation flexibility. 9
The four-division systems are the long-10
term cooling system, emergency feed water system, 11
essential electrical power, and essential cooling 12
water system. 13
So continuing with the theme of the 14
ACR-1000 four-quadrant approach, you will see here 15
another perspective of the overall arrangement of 16
major systems components within the containment 17
building together with the four quadrants which 18
surround the containment building marked in various 19
colours. 20
Many of the safety systems are included 21
within the containment boundary. Some systems, as we 22
outlined in the previous slide, are duplicated in the 23
four quadrants that surround the containment. So 24
within the containment you can see in the centre, the 25
13
reactor core, calandria and the feeders. You will see 1
within each of the partially shown steam generator 2
compartments, each of the four steam generators. To 3
the left, there is the pressurizer and you can see two 4
of the heat transport systems. Towards the top of the 5
containment, you will note that there is the reserve 6
water tank. 7
We now turn to an overview of the 8
safety systems and other safety features that are 9
available to control and mitigate against various 10
events that are postulated to occur. Such events 11
include external events such as seismic events and 12
other natural events, and what I’ll refer to as 13
internal events. 14
These are, for example, loss of coolant 15
accidents, loss of primary-circuit forced circulation, 16
and secondary side events. Depending on the frequency 17
of these postulated events, we call these anticipated 18
operational occurrences. These are those that are 19
expected to occur perhaps once of twice or more during 20
the lifetime of the plant; design-basis accidents, 21
those accidents which we do not expect to occur, but 22
because of prudence, we require that the designs 23
provide provisions to limit the risk to very 24
insignificant amounts. 25
14
And beyond design-basis accidents, 1
including severe accidents, those accidents of a very, 2
very low frequency, one in ten to the minus six per 3
annum that we expect never to occur but for which it 4
is possible to mitigate, thereby reducing the 5
consequences. 6
Overall, this is the philosophy of the 7
application of the defence in depth, to do what can be 8
done to reduce the consequences of accidents 9
irrespective of their probability. 10
Note I have included the control 11
systems at the top of the slide. Strictly speaking, 12
they are not classified as a safety system but they 13
nevertheless play an important role in the overall 14
plant operation and the control of the plant to avoid 15
upset conditions or anticipated operational 16
occurrences. In this sense they are safety related. 17
Control systems are used to control the 18
reactor of operational parameters such as reactor 19
power, primary circuit liquid inventory, temperature 20
and pressure to maintain these within normal operating 21
ranges. In addition, control systems are important in 22
avoiding upset conditions from progressing to more 23
demanding conditions that require safety systems to 24
perform. 25
15
The ACR includes two shutdown systems 1
that can be tripped to shut down the reactor and stop 2
the fission reaction in the core. These are, as we 3
saw in the previous diagram, shut-off rods which poise 4
just above the reactor core and shut down System 2, 5
which comprises pressurized tanks of poison which can 6
be injected into the moderator in the calandria. 7
The design includes an emergency core 8
cooling system consisting of passive core make-up 9
tanks, passive accumulators and a pumped low-pressure, 10
long-term cooling system. In addition, there is also 11
an emergency feed water system that activates in the 12
event that the normal feed water system does not 13
operate as designed. 14
The containment system consists of a 15
reinforced concrete structure with a stainless steel 16
liner. There are systems including an isolation 17
system to isolate the containment in the event of a 18
potential accident. There are also systems that are 19
available to be used in the event of a very low 20
frequency severe accident, and these include the 21
calandria, passive auto catalytic recombiners to 22
control the level of hydrogen, and the containment 23
itself. In addition, there are other safety support 24
systems, such as the reserve water system and 25
16
essential services. 1
The purpose of this slide is simply, 2
again, to illustrate the two shut-down systems of the 3
ACR-1000. These are two diverse and independent shut-4
down systems that are common to all CANDU types. Both 5
shut-down systems execute their function via the low 6
pressure moderator system. 7
Moving on, this is an illustration of 8
the emergency core injection system. The four smaller 9
tanks -- sort of to the leftish middle of the diagram 10
-- are the core make-up tanks which operate at high 11
pressure to make up the core inventory at high 12
pressure. 13
In addition, there are six accumulator 14
tanks from the middle to the right of the diagram 15
which can add water passively to the heat transport 16
system once the pressure has dropped below a 17
particular value. 18
Once the accumulators have depleted 19
their inventory, there is another low-pressure, long-20
term cooling system which provides for long-term 21
cooling of the core. That's not shown in this 22
diagram. 23
This illustrates sort of overall -- I'm 24
not going to go into any of what each of these pipes 25
17
mean -- but it gives you a sense of how everything in 1
a sort of three-dimensional aspect fits within the 2
containment. And then once again you can see all of 3
the major features of the ACR-1000. As noted 4
previously, the containment surrounds all of the 5
important structure systems and components and in 6
particular those important to safety. 7
So this completes our description of 8
the ACR-1000 technology, and we will move on now to 9
describe AREVA's US EPR Light Water Reactor design. 10
The EPR is designed by AREVA. The 11
design is based on established pressurized water 12
reactor technologies utilizing the vertical reactor 13
pressure vessel design. 14
The design is built on proven 15
engineering concepts of the established N4 and KONVOI 16
technologies; those technologies established in 17
Germany and -- France and Germany. It uses light 18
water as the coolant which also acts as the moderator. 19
Note that there is not an independent moderator system 20
for this design. The fuel is of a standard 17 by 17 21
design and finally note that fuelling is done during 22
outages. 23
The AREVA design is built on the 24
experience of 4-loop PWR technology, once again 25
18
incorporating feedback from existing designs and 1
existing operations. The typical time between 2
fuelling outages is between 18 and 24 months. 3
Once again, we describe an overview of 4
the key parameters. This design produces a thermal 5
power of approximately 4,600 megawatts which converts 6
to approximately 1,600 megawatts electrical. 7
The core contains 241 fuel assemblies 8
arranged in a vertically oriented open lattice 9
configuration inside a reactor pressure vessel. Each 10
of those fuel assemblies is a square 17 by 17 array 11
containing 265 fuel rods. The reactor coolant system 12
uses light water as the coolant which also acts as the 13
moderator. The fuel is enriched with U-235 up to 5 14
percent by weight. The operating pressure and 15
temperature are 15 Mpa and 330 Celsius, respectively. 16
With the exception of the overall power 17
and the number of fuel assemblies which are larger 18
than for existing light water reactors, all other 19
parameters are similar to those used in existing light 20
water reactors. 21
This illustrates, in a general way, the 22
EPR layout. In particular, I would draw your 23
attention to -- as marked kind of to the top left -- 24
the reactor building which is in the centre, and the 25
19
four so-called safeguard buildings. 1
One, which is to the left of the 2
containment, four which is to the right and then two 3
and three which are sort of behind, between the 4
reactor building and the turbine hall. 5
The safeguard buildings contain a lot 6
of the –- together with the containment -- a lot of 7
the safety related and safety equipment. 8
The EPR is a conventional four-loop 9
pressurized water reactor design; as indicated proven 10
by a number of years of design and licensing and 11
operating experience. 12
NSSS, Nuclear Steam Supply System, is a 13
popular acronym used in the US. Volumes have been 14
increased compared to existing PWRs, which allow for 15
operator grace periods longer than for some of the 16
existing light water reactor technologies. 17
So we have, again, at the centre of the 18
picture, the reactor pressure vessel surrounded by 19
four steam generators and towards the back of the 20
picture, the pressurizer. 21
Close to each of the steam generators -22
- and you can see two of them at the front -– are the 23
reactor coolant system pumps. The flow in the core –- 24
and I have some diagrams coming up that will make this 25
20
more clear, but bear with me please. 1
The core is centred within the reactor 2
pressure vessel. The flow comes up through the core. 3
It comes out of the hot leg to the steam generator 4
through the U-tubes of the steam generator, through 5
that inverted U-tube, which is called the loop seal, 6
to the reactor coolant pump and then back into the 7
vessel via the cold leg. 8
There is an annulus within the reactor 9
pressure vessel which then collects the cold water 10
from all of the cold legs down into the lower plenum 11
and then it comes back up through the centre of the 12
pressure vessel through the core. All of those four 13
loops are essentially identical, with the exception 14
that one is attached to the pressurizer, again, for 15
pressure control. 16
This illustrates I think what I just 17
described on the previous slides. The only thing that 18
I would perhaps draw your attention to is to the 19
immediate left of the reactor pressure vessel, the 20
pressurizer on which there are four valves. Two of 21
those valves are for pressure relief. The other two 22
are for severe accident purposes and I will describe a 23
bit more about those in a slide coming up. 24
Once again, this is a visualization of 25
21
the same outlay from a bird’s eye perspective from a 1
plan view. So you can once again see the rough layout 2
of the pressure vessel in the centre, the steam 3
generators at the two sides and, in particular, the 4
cold and the hot legs. 5
So I will take a little time to -– I 6
explained before a little bit about the direction of 7
the flow, how it pertains from the pressure vessel to 8
the steam generators, et cetera. So this gives you an 9
outline of what the pressure vessel looks like. 10
In the centre, there is a core which 11
consists of all of the fuel assemblies. You will 12
notice on the left, that is a cold leg coming into the 13
pressure vessel. The water comes down the annulus, 14
goes up through the fuel assemblies in the centre of 15
the core, and then it proceeds out of the right hand 16
hot leg. 17
One other thing that I probably should 18
point out here is one of the key differences of this 19
design and previous PWR designs is the lack of 20
penetrations in the lower head and, once again, that 21
is quite deliberate for dealing with severe accidents. 22
You will also note at the top, 23
immediately above the core, there are a number of 24
devices. These are the control rods which are used to 25
22
control the fission reaction and which are also used 1
to shut down the reactor as and when needed. 2
This slide illustrates the overall 3
arrangement of key components within the reactor 4
building and also the four-train concept. Important 5
systems are duplicated in each of the four safeguard 6
buildings, so once again you can see the arrangement 7
of the four steam generators, the safeguards buildings 8
which are to your left where there are two, towards 9
the front and to the rear where there are one each. 10
You will also note the sort of white 11
space there immediately in front of the reactor 12
pressure vessel, and that is there as a core spreading 13
area in the event of a severe accident and is a 14
feature I will describe in a later slide. 15
So, once again, we will talk about the 16
safety systems available; that are available to 17
control and mitigate against various events that can 18
be postulated to occur. Again, I would note that the 19
control systems are not strictly classified as a 20
safety system but, as we said before, they play an 21
important role. 22
There are two means of shutting down 23
the reactor, a rod-based system which uses the rod 24
cluster control assemblies. In addition, there is 25
23
also an extra borating system. 1
The design includes an emergency core 2
cooling system consisting of passive accumulators, 3
pumped medium-pressure injection, and a low-pressure, 4
long-term cooling system. There is also an emergency 5
feed water system that activates in the event that 6
normal feed water does not operate as designed. 7
The containment system consists of a 8
reinforced concrete structure with a stainless steel 9
liner. It is double-walled and there is a containment 10
isolation for the containment itself, and there is 11
ventilation of the annulus between the two walls of 12
the concrete structure. 13
There are also systems and components 14
that are specifically designed to be used in the event 15
of a very low frequency severe accident, including the 16
severe accident valves, the re-combiners to control 17
the level of hydrogen, and the core melt spreading 18
compartment that we showed earlier, together with core 19
melt cooling. And, of course, the containment itself 20
plays an important role. 21
In addition, there are a number of 22
safety support systems such as the in-containment 23
refuelling water storage tank and essential cooling 24
water and surface water, and essential electrical 25
24
power supplies. 1
This illustrates one of the rod plastic 2
control assemblies which form the base -- form the rod 3
base shutdown system. Each of these assemblies has 24 4
rods and provides both shutdown and control functions. 5
In preparation, I realize that this had 6
an awful lot of acronyms on it -- I apologize -- so I 7
will go through it. So this illustrates, in pictorial 8
form, the ECC, emergency core cooling system; SIS, 9
safety injection system; RHR, residual heat removal. 10
IRWST is the in-containment refuelling water storage 11
tank. LHSI is the low head safety injection and MHSI 12
is the medium head safety injection. 13
So the typical, if you like, operation 14
of these systems together is that in the event of an 15
accident that requires this system to perform, 16
typically the accumulators will come in; they will, at 17
a relatively high pressure. 18
They are passive. They will empty 19
automatically, and then you will switch to a medium 20
head safety injection which is pumped -- of which, 21
again, there are four pumps. 22
And that will take you through the 23
period of the transient where the pressure is still 24
moderately high but is decreasing, and then eventually 25
25
you'll get to the low head safety injection which then 1
can pick up liquid from the bottom of the reactor 2
vault and pump it and cool it to keep the core cool 3
over a very, very long period of time. 4
One of the, perhaps, different aspects 5
of the EPR design is the shielded containment. The 6
containment structure consists of an inner wall using 7
post-tension concrete and an outer wall of reinforced 8
concrete. 9
The outer wall provides protection 10
against things such as external events, including 11
large airplane crashes. The annulus is maintained 12
sub-atmospheric and is built to eliminate, to the 13
extent practicable, the release of radioisotopes into 14
the environment for all types of accidents. And as we 15
pointed out before, the containment plays a 16
particularly important role during -- in the event of 17
severe accidents. 18
This is a feature of the -- that is 19
specific to the EPR design. It is one of the 20
provisions in the design to deal with severe 21
accidents; that is to say those accidents where there 22
is significant core damage and there is core melt. 23
In the event that the core melts, it 24
will eventually relocate to the bottom of the reactor 25
26
pressure vessel. The bottom of the vessel is then 1
designed to fail in a controlled and predictable way 2
so that the core melt flows into a wide spreading area 3
which is the area that you can see in the inserted 4
picture, and which can then be subsequently cooled. 5
And this way, the consequences of such severe 6
accidents can be controlled. 7
This is a picture of the pressurizer 8
discharge valves arrangement. It shows on the top of 9
the pressurizer the two types of valves that are 10
connected. On the left, the safety valves. The 11
purpose of these is to provide pressure relief during 12
accidents should pressure relief be required. 13
And then above and to the right, severe 14
accident valves are designed to provide rapid pressure 15
relief during a severe accident to avoid the 16
possibility of what are referred to as “high pressure 17
melt scenarios”; those that could potentially fail the 18
pressure vessel at high pressure. 19
This completes our description of the 20
EPR technology. 21
So, finally, we come to the 22
Westinghouse technology, the AP1000. 23
I do not have a separate slide that 24
illustrates the sort of general arrangement and 25
27
layout, but you can see from this that it's a 1
relatively compact station. 2
To the right, you have the turbine hall 3
and then towards the centre of the picture you have 4
the containment together with its shielding building. 5
The AP1000 is designed by Westinghouse 6
Electric Company. The design has evolved from 7
established PWR technology using the vertical reactor 8
pressure vessel design. The design includes a number 9
of passive safety features that use light water as the 10
coolant, which also acts as the moderator. 11
The fuel is of a standard 17 by 17 12
design and fuelling is done offline during outages 13
and, again, the typical time between those outages is 14
between 18 and 24 months. 15
The design retains some of the key 16
features of the PWR technology, in particular the 17
reactor pressure vessel and the fuel, but at the same 18
time it introduces some significant innovations with 19
regard to passive safety features. 20
This slide presents some of the key 21
parameters. The design produces approximately the 22
power of 3,400 megawatts which converts to 23
approximately 1,100 megawatts electrical. 24
The core contains 157 fuel assemblies 25
28
ranged in a vertically oriented open lattice 1
configuration inside a reactor pressure vessel. Each 2
of those fuel assemblies is a square 17 by 17 array 3
containing 264 fuel rods. 4
The reactor coolant system uses light 5
water as the coolant which also acts as the moderator. 6
As with the EPR, the fuel is enriched with U235 up to 7
5 percent by weight. The operating pressure and 8
temperature are 15.5 Mpa and 325 Celsius, 9
respectively, once again, similar to the EPR 10
technology. All the parameters are similar to those 11
used in existing light water reactors. 12
A version of the AP1000 design has 13
received design certification from the USNRC including 14
those aspects identified in the left-hand side of the 15
slide; the containment, the auxiliary building and 16
annex buildings, the turbine building and radwaste 17
building, the diesel generator building and everything 18
therein and the associated yard structures. 19
The right-hand side of the slide 20
indicates some of the passive features of the design; 21
core cooling, control room habitability, the passive 22
containment cooling system, the seismic fire 23
protection and its passive security features. 24
This illustrates the reactor coolant 25
29
system. It shows the general layout of the key 1
components. Towards the bottom you can see the 2
reactor pressure vessel. To the side of that, there 3
are the two steam generators and then immediately 4
beneath each of the steam generators, you can see two 5
of the high inertia canned motor pumps. And then 6
towards the top of the picture, once again you see a 7
pressurizer which controls the pressure. 8
The flow within the pressure vessel, 9
the reactor pressure vessel, is similar to that which 10
I described for the EPR design. The general 11
arrangement within the pressure vessel is very similar 12
in terms of there being an annulus, a central core, et 13
cetera. The difference here is that you’ll note that 14
there are two loops but there are two cold legs that 15
go to each steam generator and then one hot leg that 16
returns. 17
Finally, I would notice that one of the 18
differences in terms of fluid flow here is -- that has 19
some implications for the way certain accidents 20
progress, is the lack of the loop seal between the 21
steam generator and the reactor coolant pump that was 22
for the EPR design. 23
This illustrates the fuel assemblies 24
used for the AP1000 design. The dimensions would be 25
30
typical for PWR fuel so you can take those as being 1
very representative of what the EPR fuel would look 2
like. 3
The height is approximately 4.6 metres. As we 4
said before, they are 17 by 17 fuel assemblies, 5
incorporating design features that I think are 6
probably common to most pressurized water reactor fuel 7
designs, including, in particular, resistance to 8
debris and again certain kinds of appendages here such 9
as you can see up through the dark bands on the fuel 10
assemblies which are mixing grids, once again to 11
improve heat transfer and fluid flow. 12
Once more we will give an overview of 13
the safety systems and other safety features that are 14
available to control and mitigate against various 15
events that could be postulated to occur. Once again, 16
I would say control systems are not classified as 17
safety systems as such, but play an important role. 18
The primary means of shutting down the reactor is a 19
rod-based system which uses the rod-cluster control 20
assemblies that we showed -– or a very similar design 21
that we showed in the EPR presentation. 22
In addition, there are many other 23
sources of water such as within the emergency core 24
cooling system, which are borated, which will shut 25
31
down the fission reaction. 1
The design includes an emergency core 2
cooling passive system consisting of core makeup 3
tanks, passive accumulators and a passive low pressure 4
long-term cooling system. In addition, there is an 5
automatic depressurization system. This is something 6
that is unique to the Westinghouse design. 7
The function of the depressurization 8
system is to provide a means of reducing the reactor 9
coolant system pressure in a controlled fashion during 10
accidents in order to permit safety injection to 11
occur. The depressurization system is actuated 12
automatically with a manual backup actuation 13
capability, and has incorporated redundancy to provide 14
a very high level of reliability. 15
The containment again is different for 16
Westinghouse than both the ACR and the EPR designs. 17
The containment is a free-standing steel construct 18
surrounded by a concrete shield building. The shield 19
building provides protection against all types of 20
external events, once again including aircraft crash. 21
In the event of an accident, there is a containment 22
isolation signal that closes all the isolation valves. 23
Again, there are specific features to 24
deal with severe accidents. In the event of a severe 25
32
accident in which there is core melt, safety and 1
safety-related systems are designed to retain the core 2
melt within the pressure vessel itself and to avoid 3
failure of the pressure vessel. This is described in 4
the next slide. 5
In addition, there are safety support 6
systems, including the in-containment refuelling water 7
storage tank. 8
This is just a schematic of the in-9
vessel retention capability of the AP1000. Again, the 10
approach to severe accidents is different for this 11
design than the others. The AP1000 is specifically 12
designed for in-vessel retention of molten core 13
debris. That being said, in application of the 14
defence-in-depth principle, the reactor cavity designs 15
incorporate the features that extend the time to base 16
melt-through in the event that that pressure vessel 17
should fail. 18
So again, I would note that within the 19
pressure vessel there are no penetrations below the 20
nozzles. The reactor vessel insulation design allows 21
cooling water flow path on the outside of the vessel 22
to take away the heat in the event that there is this 23
kind of accident. 24
There is cooling flow driven by natural 25
33
circulation. The water source that keeps this filled 1
up with water is the in-containment refuelling water 2
storage tank. Once again, the automatic 3
depressurization system plays a role in relieving any 4
pressure build-up. 5
This illustrates the passive core 6
cooling system. Again, I apologize for the number of 7
acronyms. RV, reactor vessel; SG, steam generator; 8
CMT, core make-up tank; ACC, accumulator; and the 9
IRWST, in-containment refuelling water storage tank. 10
In very general terms, the general 11
sequence of operation of the systems is, first, once 12
the pressurizer -- in the event that you had, for 13
example, a lost of coolant accident, the pressurizer 14
would lose its inventory. There would be a signal 15
that would open the tanks marked CMT, core make-up 16
tanks. These would deliver their inventory into the 17
coolant system at a relatively high pressure. 18
Once their inventories are depleted, 19
you would then move to the tanks marked ACC, the two 20
accumulators, and as the pressure drops, eventually 21
you would end up using the long-term cooling passive 22
system. 23
This illustrates the passive 24
containment cooling system. As I indicated before, 25
34
the containment is quite different for the 1
Westinghouse design. It's a steel containment 2
surrounded, as you can see here, by a robust concrete 3
structure that shields the containment. 4
This is specifically designed so that 5
you can keep the containment cool by natural means in 6
a passive way. So once again, you see the reactor 7
pressure vessel and the pressurizer immediately to the 8
left of that. The tank water to the left is the IRWST 9
and then to the right of the diagram you can see the -10
- to the top, the core make-up tank, to the bottom, 11
the accumulator. 12
So the cooling comes from internal 13
condensation of water that is in the atmosphere, the 14
natural circulation, plus gravity-fed water from the 15
tank that sits on top of the containment structure. 16
So that completes our description of 17
the AP1000 technology. 18
So in summary, I would like to make a 19
few final remarks regarding some of the similarities 20
and differences. 21
The first point is that, despite the 22
obvious differences between the basic technologies, at 23
a high level from a safety perspective there are more 24
similarities than there are differences. 25
35
All the technologies incorporate 1
defence-in-depth principles, are based on sound 2
engineering principles, and demonstrate a high level 3
of safety. 4
All the technologies include design 5
provisions for the control of anticipated operational 6
occurrences, design provisions for the control and 7
mitigation of design-basis accidents and specific 8
provisions for the mitigation of very low frequency 9
severe accidents. 10
All the technologies incorporate 11
passive safety features, some more than others, have 12
robust containments, and have been designed with a 13
modular construction in mind. 14
There are some differences with respect 15
to overall power, the basic pressure boundary 16
technology, and the approaches to mitigate severe 17
accidents and with respect to just the physical size 18
as well. 19
So in conclusion, we have provided a 20
high-level overview of the three technologies, focused 21
on design aspects that could have bearing on the 22
Environmental Impact Statement. 23
We have provided information on the 24
principal features of the designs, key operational 25
36
parameters, normal operation, control and mitigation 1
of potential accidents. 2
And at the appropriate time, we will be 3
ready to respond to questions. 4
Thank you very much. 5
THE CHAIRMAN: Thank you very much. I 6
think we'll wait for questions until we have the other 7
presentations. We'll take them all together. 8
MR. SCHWARZ: Thank you very much, Mr. 9
Chairman. 10
We will then proceed with the next 11
presentation which will be on condenser cooling water 12
systems and their environmental impacts. And I will 13
call on Mr. Malcolm McKee to make that presentation. 14
15
Cooling Water Systems and Associated Environmental 16
Impacts 17
18
MR. McKEE: Good afternoon. 19
As requested by the Joint Review Panel, 20
today we will be providing a presentation on cooling 21
water system technology and their associated 22
environmental impacts. 23
This technical briefing will be 24
provided by myself, Malcolm McKee, Acting Director of 25
37
the Environmental Risk Assessment Division, and we are 1
fortunate today to have in support Don Wismer, also of 2
our division. Mr. Wismer’s graduate work and his 3
career prior to joining the CNSC a few years ago 4
focused specifically on the aquatic effects of once-5
through cooling systems on the Canadian Great Lakes. 6
Today’s presentation will focus on the 7
following: We will start with introducing the basic 8
purpose of the condenser cooling water systems that we 9
are discussing. This will be followed by an 10
introduction of the basic types of cooling water 11
systems that are in use at nuclear facilities 12
throughout the world today, and we will then outline 13
the various environmental effects associated with 14
these basic types. 15
The basic elements of a nuclear power 16
plant are shown in this figure. On the left side of 17
the figure we see the reactor unit. In the centre is 18
the steam turbine and in the right is the cooling 19
water condenser system. 20
As we've heard, the basic principle of 21
a reactor involves using the heat generated within the 22
reactor to create steam to power the steam turbine, 23
which then generates electricity. 24
The steam circuit is a closed system 25
38
with water converted to steam in the steam generator 1
shown here as D, used to drive the turbine and then 2
condensed in the cooling water condenser shown here as 3
I, prior to being pumped back to the steam generator 4
once again. 5
The condenser cooling water system is a 6
separate system outlined here by the dashed line on 7
the right. The condenser cooling water system removes 8
heat energy from the steam within the condenser, 9
thereby condensing for recycling back to the steam 10
generator. 11
Note that this system is completely 12
isolated from the radioactive components of the 13
reactor. 14
There’s a range of cooling water 15
systems that may be used to operate the condenser, the 16
selection of which is independent of the specific 17
reactor technology which has just been discussed. 18
The terminology for these systems 19
varies and can become quite confusing. For this 20
presentation, we will refer to two basic categories. 21
These are open cycle, commonly called once-through, 22
and closed cycle, also referred to as re-circulating 23
systems. 24
The presentation today will focus on 25
39
two types of re-circulating systems, these will be wet 1
towers and dry towers. 2
Historically, once-through systems have 3
been the preferred designs for large power generating 4
stations when large volumes of surface water have been 5
available. 6
Here we have a simplified schematic of 7
a once-through system. We see the condenser depicted 8
in the rectangular box here. The cooling water system 9
intake comes from the surface water body, goes through 10
the condenser, picks up heat and is released directly 11
back to the original source water body. 12
As a result of their operation, once-13
through cooling water systems require large volumes of 14
water. For example, intake volumes for the once-15
through systems for the three Canadian reactor 16
stations accounting for 16 units on the Great Lakes, 17
range between 150 to 200 cubic metres of water per 18
second. To put this into perspective, this 19
approximates 5,000 to 7,000 Olympic-sized swimming 20
pools per day. 21
The other main category of cooling 22
system to be discussed today is the closed cycle or 23
re-circulating system, shown here in this schematic. 24
In these systems, condenser cooling water is 25
40
repeatedly recycled; warm cooling water exiting the 1
condenser cycles through some sort of cooling device, 2
in this case shown in blue as a tower on the left. 3
The water cools as it passes through the cooling 4
device and is re-circulated back to the condenser. 5
As a result of the re-circulation of 6
the condenser cooling water, overall water withdrawal 7
is much lower than for a once-through system. After 8
the initial filling of the CCW system, further 9
withdrawals are only required as make-up water for 10
relatively small losses associated with evaporation 11
from wet towers or blow-down from both wet and dry 12
towers. 13
Blow-down refers to the portion of the 14
circulating water flow that is removed and replaced 15
with make-up water in order to maintain the amount of 16
dissolved solids and other impurities at an acceptable 17
level within the system. 18
Re-circulating systems are used in 19
approximately 47 percent of US power plants and 88 20
percent of all coal-fired facilities built in the late 21
1990's to early 2000's in the US. 22
Of the 16 reactor units on the US Great 23
Lakes associated with US Great Lakes shoreline, 11 24
utilize once-through cooling and 5 use re-circulating 25
41
systems. Canadian reactors presently use once-through 1
systems. 2
There are a number of different types 3
of cooling devices that may be used as part of a 4
closed cycle system. While it is possible to utilize 5
large cooling ponds, often with secondary spray 6
technology, practical experience has proven them to be 7
of limited value for large facilities. 8
Hence, the most common cooling devices 9
used for large closed cooling water systems are 10
cooling towers of some form or another. Cooling 11
towers dissipate their heat from the condenser cooling 12
water by transferring the heat to the air flowing up 13
through the tower. This is usually achieved either 14
through evaporative processes in the case of wet 15
towers or convection and conduction in dry towers. 16
The tower designs also differ in their 17
means of creating the required upward air flow through 18
the tower. The most common structural designs used to 19
create this air flow are referred to as “natural 20
draft” and “mechanical draft towers”. We'll be 21
discussing each of these various types. 22
First, we'll start with wet cooling 23
towers. Wet cooling towers work on the principle of 24
directly exposing the condenser cooling water to the 25
42
atmosphere with heat being dissipated through 1
evaporative losses. The basic principle involves 2
pumping the hot, condenser cooling water from the 3
condenser circuit to the tower. Within the tower, the 4
downward flowing cooling water comes in contact with 5
the rising air and heat is lost by evaporative cooling 6
process. 7
To optimize the cooling performance, a 8
medium called fill is used to increase the contact 9
surface area between air and water flows. 10
Two types of fill are generally used. 11
Splash fill consists of material placed to interrupt 12
the water flow causing splashing which increases the 13
surface area exposure; or film fill, composed of thin 14
sheets of material upon which the water flows, spreads 15
out and, again, increases exposure for the surface 16
area. 17
Wet towers like dry towers can be 18
constructed using one of two basic structural designs. 19
These are natural draft tower structures or mechanical 20
draft tower. The difference in these tower designs is 21
primarily a factor of the means of air flow generation 22
by the tower. 23
Here we see a classic cooling tower 24
design. These are hyperbolic towers commonly referred 25
43
to as “natural draft”. In the case of both of these 1
images shown here, these are both wet natural draft 2
cooling towers. 3
If we look at the schematic on the 4
left, the hot water is pumped to the tower and sprayed 5
from above over the fill below. The schematic on the 6
left shows the hot water spray lines in blue visible 7
just below the drift eliminators, which are shown in 8
red. 9
The sprayed hot water flows or splashes 10
over the fill depending on the type of fill being 11
utilized, increasing the surface area of water exposed 12
to the atmosphere. 13
This exchange fill area is situated 14
above the cold air inlet at the base of the shell. A 15
natural upward air flow or chimney effect results as 16
air rises inside the tower as it is heated which, in 17
turn, draws in cooler air from the outside through the 18
open bottom of the tower. 19
The cool air flows through the fill, 20
draws heat from the water and thus continues to rise. 21
The cold water collects at the bottom of the tower and 22
is pumped back to the condenser. 23
To function properly, natural draft 24
towers have to be very high structures, typically 120 25
44
metres to 150 metres in height. This height is 1
required to generate sufficient upward movement of air 2
to meet the cooling requirements for large thermal 3
electric facilities. 4
Operating costs are low, as fans and 5
the energy to run them are not required, but they can 6
have high upfront construction costs, and the land 7
area requirements are quite large; for example, the 8
picture on the right shows the -- showing the visible 9
plume of moisture-laden air coming from the tower. 10
The height of these towers and the 11
periodically visible plumes can have a pronounced 12
visual impact. This visual impact generates further 13
negative response from public due to a common mistaken 14
belief that these towers are the equivalent of smoke 15
stacks with associated pollutants. 16
Other forms of towers becoming quite 17
common are mechanical draft towers shown in schematic 18
form here. Once again, both of these examples are wet 19
mechanical draft towers. These towers rely on large 20
power-driven fans to force or draw air through the 21
tower. 22
This forced air flow allows 23
substantially shorter tower designs than that of a 24
similar capacity natural draft tower. Force draft 25
45
towers have the fan situated at the bottom of the 1
tower pushing air upwards, while induced draft towers 2
have the fan situated at the top to draw air up 3
through the tower. 4
The wet cooling principle is the same 5
as shown in the previous natural draft example. 6
Piping within the tower sprays the warm condenser-7
cooling water downward over the fill area using one of 8
the two configurations shown in this slide. 9
On the left, the increased water 10
surface area produced by the fill is brought into 11
contact with upward air-producing evaporative heat 12
loss. 13
The design schematic on the right has 14
an improved heat removal as the result of producing 15
both counter-flow upward and downward interaction 16
between water and air, as well as cross-flow or 17
lateral interaction. This improves heat removal. 18
In this photograph, we see an external 19
view of the two banks of mechanical draft towers used 20
for operating this reactor cooling condenser water 21
system. 22
Another form of cooling tower is dry 23
cooling towers. Dry cooling systems have been the 24
least used systems as they have much higher capital 25
46
costs, higher operating temperatures and lower 1
efficiency than wet cooling systems. Historically, 2
dry cooling systems are being used when there is 3
insufficient water or where the water is too expensive 4
to be used in an evaporative process. 5
However, in recent years dry cooling 6
towers have received a great deal more interest due to 7
improved designs and changing environmental laws with 8
respect to water usage, making them more economical. 9
These towers are referred to as “dry 10
towers” as there is no direct exposure of the 11
condenser cooling water to the atmosphere. Instead, 12
in dry cooling systems, the cooling water is forced 13
through a network of fins, tube elements, coils or 14
conduits. 15
Heat transfer occurs as a result of 16
conduction and convection to air forced across the 17
cooling elements. The principle is similar to that of 18
a car radiator. Again, as was the case for wet 19
towers, dry cooling may involve the use of either 20
natural draft or mechanical draft structure towers. 21
Here we see a dry cooling system 22
situated within a natural draft tower though, as 23
mentioned, mechanical draft towers can also be used. 24
The schematic to the right, the condensing cooling -- 25
47
the warm condensing cooling water enters through the 1
blue piping. It's forced through the red fins to 2
increase the surface area to increase cooling 3
efficiency. Cool air flows into the tower and is 4
drawn up through the cooling fins with heat 5
dissipation resulting. 6
There are also what are referred to as 7
“hybrid systems”. Hybrid systems essentially use a 8
combination of two or more of the previously described 9
technologies. 10
The simplest and oldest hybrid system 11
can be best described as “a once-through with a helper 12
tower”. This involves the additional cooling of the 13
condensing cooling water in a cooling tower prior to 14
release of the initial source water body, therefore, 15
minimizing thermal releases. 16
Two of the more common types of hybrid 17
cooling systems go by the rather un-dramatic names of 18
“wet with part dry” and “dry with part wet”. 19
Wet with part dry -- also known as 20
plume -- one of the problems with wet towers is that 21
in cold and humid climates, a moist visible plume of 22
warm air can form that poses potential fogging and 23
visibility and icing issues. 24
In these part dry or plume-abatement 25
48
towers, a dry section above the wet zone provides some 1
dry cooling to the exhaust plume to remove condensing 2
water vapour. These towers are common in Germany and 3
England where plume mitigation has often been 4
required. 5
The problems with full dry towers are 6
centred on loss of performance in very hot weather. 7
This can be mitigated with the use of water spray 8
systems often usually just during these periods of 9
high atmospheric temperature, where spray is used to 10
cool the thinning tubes to improve the efficiency. 11
This schematic shows the basic 12
principle of the wet-dry hybrid tower, or plume-13
abatement tower. As we see, the tower combines both 14
wet and dry principles with the dry portion situated 15
above the wet, thereby mitigating the moist plume and 16
the issues associated with it. 17
In this slide, in the top right, we see 18
one of the first wet-dry towers built for a reactor. 19
This is a reactor unit in Germany, built in the 1980s. 20
Below we see a picture of the Calvert Cliffs reactor 21
site in Maryland, USA. This reactor facility is 22
presently undergoing USA approval to add two 1600-23
megawatt units and they are presently proposing the 24
utilization of a hybrid tower, as shown in the upper 25
49
right portion of the schematic. 1
Now that we have a basic understanding 2
of the types of cooling technologies available for use 3
in nuclear facilities, we will outline the 4
environmental issues associated with these designs. 5
The US Nuclear Regulatory Commission’s 6
generic environmental impact assessment and the CNSC-7
required site-specific environmental risk assessment 8
for existing Canadian reactors, have all identified 9
the condenser cooling water system as the primary 10
source of actual and potential environmental impacts 11
related to the routine operation of nuclear power 12
plants. Hence, they should be one of the focal 13
elements within an environmental risk assessment. 14
Before discussing potential 15
environmental impacts, it’s necessary to differentiate 16
between potential hazards and realized effects. 17
Potential hazards are those 18
interactions with the environment that have the 19
potential for harm but can often be mitigated through 20
design modifications or administrative actions. 21
Realized effects are those effects 22
that, even after mitigation, are expected or known to 23
harm individual biota but may be considered acceptable 24
if they do not put populations of biota at risk. 25
50
We’ll start then with the once-through 1
cooling systems. AS previously mentioned, once-2
through cooling systems withdraw large volumes of 3
water. As a result, they have a number of potential 4
and realized impacts on the aquatic receiving 5
environment. The major environmental issues for once-6
through cooling systems are bulleted here. 7
These involve impingement and 8
entrainment of aquatic biota; discharge of heated 9
water to the receiving environment; releases of 10
chemicals in discharge water such as biocides and 11
other chemicals associated with managing corrosion and 12
scaling; physical harm with construction of intake 13
structures canals et cetera; and changes in local lake 14
current and bed scour. These will be addressed in the 15
following slides. 16
Impingement and entrainment remains the 17
largest environmental impact for operating nuclear 18
facilities in Canada. These represent realized 19
effects rather than potential hazards. Impingement 20
involves the killing of aquatic biota, usually fish, 21
as a result of being trapped against the intake 22
screens of the once-through systems. 23
Entrainment involves the actual intake 24
and passage of aquatic biota such as small fish, fish 25
51
larvae, fish eggs and aquatic invertebrates through 1
the cooling water system, with a certain proportion 2
being killed or injured as a result of physical 3
abrasion or exposure to heat, biocides or other 4
chemicals. 5
Impingement losses for the Canadian 6
reactors on the Great Lakes vary depending on the 7
mitigation technology incorporated into the design of 8
the cooling water intake structure. Reactors with 9
surface shore-side intake structures produced 10
impingement fish mortality losses approximating 20 11
tonnes per year. 12
Reactor units employing deep offshore 13
intakes with velocity caps have experienced 14
impingement losses ranging from 8 to 20 tonnes per 15
year, with impingement being substantially lower for 16
reactor units using deep offshore pre-cast porous 17
bottom intake designs that will be shown later in this 18
presentation. 19
Impingement losses with this design 20
have been substantially lower, ranging from 300 to 600 21
kilograms per year. Hence, as we see, impingement 22
mortality can be reduced but not completely eliminated 23
with the use of appropriately designed and sited 24
intake structures. 25
52
Entrainment losses are more difficult 1
to quantify as it is more difficult to determine the 2
number of biota entrained and the proportion killed or 3
harmed by their passage through the system. Unlike 4
impingement, the magnitude of entrainment does not 5
appear to substantially differ among present intake 6
designs at Canadian reactors, though this is likely a 7
result of largely varying sampling results. 8
The mortality resulting from 9
entrainment has also been difficult to determine. 10
Survival estimates have ranged from 25 to 90 percent 11
depending on the reactor station and fish species 12
being investigated. Survival rates for invertebrates 13
are reported in the scientific literature to be 14
relatively high. 15
The potential risk for entrainment to 16
fish population is estimated, taking into account the 17
already natural high mortality rates for eggs and 18
larvae. The ecological significance of entrainment, 19
like impingement, is very much a site-specific issue, 20
depending upon the size of the local affected 21
population and the geographic range. 22
Reduction of entrainment through intake 23
structure is challenging and has had mixed success, as 24
many of the mitigation structures are prone to 25
53
clogging and can impair water inflows that are 1
required for efficient cooling. 2
Cooling water intake structure 3
impingement and entrainment impacts have received a 4
great deal of attention in recent years in the United 5
States. The Environmental Protection Agency in the US 6
has launched a series of investigations and studies 7
into the environmental impacts of cooling water 8
technologies, focussing on impingement and 9
entrainment, assessment of best technology available 10
for minimizing these, including the economic 11
feasibility of requiring the use of these 12
technologies. 13
It was determined that the present 14
aquatic impacts from cooling water intake structures 15
was unacceptable. This resulted in the passing of the 16
phase 1 rule in 2001 that essentially restricts intake 17
performance, such that the equivalent of a re-18
circulating system is required. This rule essentially 19
eliminates the use of once-through cooling systems for 20
new reactors at greenfield sites in the United States. 21
The phase 2 rule passed in 2004, but 22
presently under appeal, applies to all large existing 23
cooling water intake structures. The phase 2 rule 24
calls for the addition of mitigative technology to 25
54
substantially reduce impingement entrainment at the 1
existing facilities. This rule will, therefore -- 2
depending on the appeal process -- require extensive 3
retrofitting for large existing once-through systems 4
in the US. 5
Another environmental interaction 6
associated with the once-through cooling systems 7
involves the thermal release of the warm cooling water 8
back to the source water body. 9
Thermal discharges have the potential 10
to pose a hazard to aquatic biota through either 11
direct mortality from thermal shock of incubating 12
eggs, primarily resulting from sinking winter plumes, 13
or thermal shock to adult fish residing in discharge 14
channels if there is a rapid change in temperature as 15
a result of a reactor shutdown for maintenance or 16
other issues. 17
There are also indirect effects on 18
developmental rates of aquatic biota; alteration of 19
habitat availability due to changes in water 20
temperature and species-specific temperature regimes 21
and destruction of normal shoreline fish movement 22
patterns. 23
Thermal effects can be mitigated, 24
though, through careful offshore sighting and the use 25
55
of advanced diffuser technology, an example of which 1
will be shown later in the presentation. 2
The release of biocides and other 3
hazardous substances associated with management of the 4
cooling systems also have potential hazards to the 5
receiving environment. 6
For once-through cooling systems in the 7
Great Lakes, the primary issue is the use of biocides 8
that are required for managing nuisance species such 9
as zebra mussels. The most efficient and effective 10
biocide for zebra mussels is chlorine, however, its 11
very effectiveness is due to its extreme toxicity to 12
aquatic organisms. Hence, overuse can kill biota in 13
the receiving waters upon discharge. 14
Studies of alternative biocides have 15
been completed. The conclusion has been that 16
carefully managed use of chlorine in low 17
concentrations during periods of least risk to aquatic 18
biota is the most efficient practice. This 19
substantially decreases risk to aquatic biota. 20
In addition to thermal effects from the 21
discharge, the large volume and velocity of the 22
discharge can affect local aquatic ecology by 23
substantially altering shoreline currents, 24
depositional patterns and producing bed scour. 25
56
There are also localized physical 1
aquatic habitat impacts with the result of the 2
construction of the facilities themselves. The three 3
potential effects discussed here in this slide can all 4
be mitigated with the use of best-available technology 5
and environmental management plans. 6
This schematic illustrates the basics 7
of the Darlington once-through system. The intake and 8
discharge structures at this facility were developed 9
with best-available technology at its time of 10
construction and hence, it has had the least impact of 11
all the Canadian reactors located on the shores of the 12
Great Lakes. 13
It is the design of the intake 14
structures and the discharge diffusers that have 15
produced the majority of the benefits. 16
The intake structure shown on the left 17
was designed to minimize impacts by locating it well 18
offshore in areas where lower fish and invertebrate 19
activity occur, and it was specifically designed to 20
greatly reduce inflow velocity at any one point of 21
space within the intake. As a result of this design, 22
impingement and intake of large fish is in order of 23
magnitude lower than at the other facilities using 24
either shoreline intake structures or offshore 25
57
velocity caps, however, losses of egg and larvae are 1
believed to be similar. 2
The diffuser system is shown on the 3
right. This diffuser system was designed with the 4
latest thermal- plume mitigation technology during its 5
construction and involves a deep offshore diffuser 6
designed and located to minimize disruption of near-7
shore lake currents and water temperatures. 8
Here we have a summary table for the 9
potential adverse effects associated with once-10
throughs. Potential adverse effects here are 11
qualitatively categorized as low, medium, or high. As 12
we move through this presentation, we will build on 13
this table adding columns for each of the cooling 14
technologies for comparison purposes. 15
First, however, we must introduce the 16
issue of energy penalty shown in the first row. This 17
refers to the reduction in energy generated per unit 18
of fuel at the power reactor related to the operation 19
of the cooling system itself. 20
This energy penalty arises from the 21
energy used to operate the system, as well as 22
reductions in turbine efficiency associated with the 23
temperature of the cooling water entering the 24
condenser. 25
58
The energy penalty for once-through is 1
classified as low and is associated with energy 2
required to run pumps and the loss of efficiency that 3
can occur during periods of warm natural water 4
temperatures such as can been experienced during peak 5
summer temperatures. 6
Before addressing the potential adverse 7
effects, it is important to differentiate, once again, 8
between potential hazards versus realized adverse 9
effects. 10
Mitigation and management under CEAA 11
depends upon criteria for significance which are 12
usually based on ensuring there are no population 13
level effects. For example, impingement is based on 14
observation of dead fish in power plants, screenhouse’ 15
debris bins, and entrainment kills a variable fraction 16
of fish larvae and eggs. These are more than hazards 17
and may be significant depending on the number of 18
killed and the size and types of the locally affected 19
fish populations. 20
The majority of the other adverse 21
effects that have been identified are hazards with the 22
potential to affect individual biota with further, 23
even less likely potential to affect populations of 24
biota. 25
59
Thermal hazard ranges low to high 1
depending upon whether the discharge point is at the 2
shoreline or deep offshore and whether appropriate 3
diffuser technology has been implemented. 4
There are no atmospheric plume drift or 5
noise implications of concern, and that’s indicated by 6
the dashes. 7
Aquatic habitat is affected depending 8
on the type of system and the local biology, and 9
terrestrial habitat effects are low. 10
We’ll now move to wet cooling towers. 11
As previously outlined, closed cycle 12
wet cooling systems use substantially less water than 13
once-through systems, hence, aquatic impacts are 14
dramatically reduced, specifically impingement 15
entrainment. 16
The remaining potential environmental 17
issues associated with these cooling systems involve 18
chemical releases to water; blowdown containing salts, 19
biocides and other possible additives; water 20
condensate; plume and drift issues associated with 21
things as drift deposition, fogging and icing, and in 22
the management of potential human health issues. 23
Noise and land-area requirements: If 24
we start first with chemical release. Due to the 25
60
limited intake volume required to periodically 1
replenish cooling towers, the release of biocides 2
including water additives during periodic blowdown 3
replaces the impingement and entrainment as a primary 4
source of aquatic impact for wet cooling towers. 5
However, these can be readily managed with 6
interception and alternative treatment or disposal or 7
judicial release to the receiving environment such 8
that concentrations are rapidly diluted to levels 9
posing no harm. 10
The primary environmental issues 11
associated with wet cooling towers are related to 12
condensation plumes and drift. Most of the water lost 13
from a wet cooling tower, whether natural or 14
mechanical draft, escapes to the atmosphere as water 15
vapour in the exhaust flow. This can result in 16
visible plumes under specific meteorological 17
conditions with the spatial extent and density of 18
these plumes being strongly influenced by the local 19
weather conditions. 20
It is also influenced by tower design 21
with mechanical draft towers producing smaller plumes 22
generally 30 percent smaller than natural draft 23
towers. 24
These plumes can pose problems from 25
61
fogging and icing that has been documented as creating 1
dangerous conditions for local roads and for air and 2
water navigation. This has to be addressed when 3
making siting decisions related to tower placement, or 4
there’s the option of plume mitigation technology. 5
There’s a potential for condensing 6
plumes to result in ice damage to vegetation; however, 7
the U.S. Nuclear Regulatory Commission, in their 8
review of environmental impacts at sites using towers, 9
classified this as a minor environmental effect. In 10
their assessment, the largest documented incidence in 11
the study was locally restricted to 150 metres from 12
the tower and believed to result from a combination of 13
poor tower placement, a malfunctioning tower and 14
unusual weather conditions. 15
Drift refers to the tiny droplets of 16
cooling water that are entrained in the air stream 17
inside the tower and escape directly to the 18
atmosphere. This drift can contain varying amounts of 19
salts, biocides and micro-organisms. 20
The U.S. Nuclear Regulatory Commission 21
studied the potential for drift and condensation 22
plumes from nuclear facilities and concluded that 23
there are no instances where cooling tower operation 24
resulted in measurable productivity losses in 25
62
agricultural crops or measurable damages to ornamental 1
vegetation. They conducted a similar study on cooling 2
tower drift effects on native plant communities as 3
well. The conclusion was that there were no instances 4
where cooling tower operation had resulted in 5
measurable degradation of the health of natural plant 6
communities. 7
Microbial dispersal and exposure to 8
workers in the public is a potential hazard for 9
cooling towers if not properly managed. Hence, 10
monitoring of cooling water quality and the 11
application of biocides and other additives are used 12
to impair the growth and reproduction of microbes and 13
nuisance algae. 14
Specific industry codes and regulatory 15
expectations and guidance are available for microbial 16
management of cooling tower waters. This, along with 17
the application of standard industrial hygiene 18
principles, prevents adverse health effects. 19
Wet cooling towers also have potential 20
issues related to noise and land area requirements. 21
With respect to noise, the noise 22
implications differ between the two types of towers, 23
whether natural draft or mechanical draft. Noise in a 24
natural draft tower is primarily associated with the 25
63
water cascading and flowing through the tower. 1
Mechanical draft towers have noise 2
effects primarily associated with the use of the large 3
fans to run the systems and the associated generators 4
for the fans. Hence, mechanical draft towers are 5
substantially noisier than natural draft. 6
The U.S. NRC has found no incidence at 7
operating sites of off-site noise levels posing 8
potential harm, though noise may be a nuisance factor. 9
They concluded that natural draft or mechanical draft 10
cooling towers emit noise of a broadband nature. 11
Because of the broadband characteristic of the cooling 12
towers, noise associated with them is largely 13
indistinguishable and less obstructive than 14
transformer noise or loud speaker noise. 15
Noise abatement features are now an 16
integral component of modern cooling tower designs as 17
well. 18
The final issue to be addressed here 19
for wet cooling towers is land area requirements. 20
Towers require substantial land area. Natural draft 21
towers require very large diameter bases to support 22
their great height, and mechanical draft towers 23
require land area sufficient to support the required 24
banks of towers that are needed. 25
64
For example, on the right, we see that 1
the base of the natural draft tower is very similar in 2
size to the main reactor building and associated 3
immediate support facilities. 4
On the left, we see the two parallel 5
banks of mechanical draft cooling towers required to 6
support this reactor unit. That's the two parallel 7
banks coming out from the river shoreline. 8
Now, we continue to build on our 9
summary table with the addition of a column for wet 10
towers. 11
The energy penalty is higher that once-12
through because wet towers would result in 13
approximately 2 percent less electricity output from 14
warmer condenser water affecting turbine efficiency 15
and the use of electricity to run fans and pumps in a 16
mechanical draft tower. 17
Impingement/entrainment is low since 18
lake water uses is only a fraction of once-through’s. 19
There are no thermal effects and heat load is 1 20
percent of once-through for the life of the power 21
plant. 22
Atmospheric plumes are present for 23
mechanical and natural draft wet towers. Mechanical 24
towers have no noise due to -- mechanical towers have 25
65
noise due to fans and water flow over the fill in the 1
tower. 2
Habitat effects are less for aquatic 3
biota but are higher for terrestrial with 4
approximately 15 hectares of land needed for 5
mechanical and a larger area needed for natural draft. 6
The final basic cooling system design 7
to be discussed today is the dry cooling towers. 8
Of all the cooling system options, dry 9
cooling towers have the least environmental impact, 10
but their lower efficiency, high construction costs 11
and operational costs have restricted their use. 12
Since dry cooling towers do not expose 13
the cooling water to the atmosphere, there are no 14
plume or drift issues and no evaporative losses 15
requiring make-up water. 16
This leaves dry towers with 17
environmental interactions restricted to small amounts 18
of blowdown water, noise, and land area requirements. 19
Blowdown releases are low due to less 20
concentration of salts and chemical additives as there 21
are no evaporative losses. 22
Dry cooling towers can be noisier than 23
wet as they tend to have greater fan requirements due 24
to their larger size requirements. 25
66
The largest environmental issue for dry 1
towers is their greater land area requirements. For 2
example, dry cooling towers generally require three to 3
four times the land area of a wet tower for a 4
comparable cooling capacity. 5
We now add dry towers to our summary 6
table. For dry towers, we see a substantially higher 7
energy penalty due to the electricity output -- the 8
amount of electricity output consumed by running the 9
towers themselves and lower efficiency from cooling 10
water condenser in-flow temperatures. 11
There are no impingement and 12
entrainment or thermal effects or atmospheric plumes, 13
and chemical releases are lower. 14
Noise is higher than other options to a 15
larger number of fans and the larger surface area, and 16
there are larger surface area requirements for towers. 17
As well, habitat effects will be higher 18
for terrestrial with approximately 35-hectare land 19
area requirements. 20
We now complete our summary table with 21
the addition of the final column for hybrid systems 22
that use a combination of two or more of the 23
technologies to reduce environmental impact. 24
The energy penalty is intermediate 25
67
between wet and dry. Plume and drift effects are 1
minimized, while other impacts vary depending on what 2
mix of technology is used. Comparing across all four 3
major types of cooling systems, some patterns are 4
evident. 5
Once-through cooling systems have the 6
greatest aquatic environmental effect due to ratings 7
for impingement, entrainment, thermal, and aquatic 8
habitat. Impingement and entrainment are, in this 9
case, observed realized adverse effects that are not 10
completely mitigable. 11
Thermal and habitat effects can be 12
reduced to non-hazardous levels with proper design. 13
Once-through systems require careful 14
identification and selection of best-available 15
technology for the intake and discharge structures 16
with careful consideration given to siting them 17
optimally to minimize their associated effects. 18
Cooling towers consume 2 to 10 percent 19
more energy than once-throughs, have noise and 20
atmospheric plume effects, as well as land area 21
requirements that may affect terrestrial habitat or 22
prevents their use at smaller sites that do not have 23
the required land area. 24
The atmospheric plume and drift effects 25
68
of the towers can be managed through mitigation and 1
best practices. 2
This concludes our presentation for the 3
afternoon and staff is available for questions. 4
THE CHAIRMAN: We thank you very much 5
for the presentation. We will hold questions until 6
the other presentation. 7
But right now I think we’ll take a 15-8
minute break and come back in 15 minutes. We need to 9
refresh. 10
--- Upon recessing at 2:17 p.m. / 11
L’audience est suspendue à 14h17 12
--- Upon resuming at 2:33 p.m. / 13
L’audience est reprise à 14h33 14
THE CHAIRMAN: We will continue with 15
the presentations and then we'll move on to the 16
questions. 17
MR. SCHWARZ: Thank you very much, Mr. 18
Chairman. 19
The next presentation will be on 20
radioactive waste management for new builds. This 21
presentation will be made by Mr. Don Howard. 22
Thank you. 23
24
Radioactive Waste Management for New Builds 25
69
1
MR. HOWARD: Thank you and good 2
afternoon. Again, my name is Don Howard; I am the 3
Director of the Wastes and Decommissioning Division. 4
I would like to begin by quoting from 5
the European Union which indicated that the 6
development of nuclear power is to some extent 7
dependant on the resolution of two issues: the safety 8
of nuclear facilities; and, the most important one, 9
the management of radioactive waste. 10
So in accordance with Canada’s 1996 11
Policy Framework, the waste owners or the waste 12
producers are responsible for the funding, 13
organization and operation of the waste management 14
facilities required for their wastes. 15
So in order to ensure that the wastes 16
have insignificant effects on the population and on 17
the environment as a whole, certain measures must be 18
taken to isolate the wastes from the biosphere. 19
In practice, there are two approaches 20
to the management of radioactive waste: collect, 21
process, package and store or isolate the waste; and 22
secondly, the controlled release of low-level waste 23
into the environment. 24
My presentation today will outline four 25
70
main topics: basically, waste management strategy and 1
what does that includes; low and intermediate level 2
waste; used nuclear fuel; and finally, the short and 3
long-term plans for the management of radioactive 4
waste. 5
An applicant is required to provide two 6
main documents. One is a waste management strategy. 7
The strategy must address the principles outlined in 8
CNSC Regulatory Policy P-290. 9
And the principles include that the 10
generation of radioactive waste is minimized to the 11
extent practicable by the implementation of design 12
measures, operating procedures and decommissioning 13
practices; that the management of radioactive waste is 14
commensurate with this radiological, chemical and 15
biological hazards to the health and safety of persons 16
and the environment and to national security; the 17
assessment of future impacts of radioactive waste on 18
the health and safety of persons and the environment 19
encompasses the period of time when the maximum impact 20
is predicted to occur; the predicted impacts on the 21
health and safety of persons and the environment from 22
the management of radioactive waste are no greater 23
than the impacts that are permissible in Canada at the 24
time of the regulatory decision; that the measures 25
71
needed to prevent unreasonable risk to present and to 1
future generations from the hazards of radioactive 2
waste are developed, funded and implemented as soon as 3
reasonably practical; and, finally, the trans-border 4
effects on the health and safety of persons and the 5
environment that could result in the management of 6
radioactive waste in Canada are no greater than the 7
effects experienced in Canada. 8
Then this brings us to the waste 9
management plan or program, and basically this 10
document must demonstrate how the applicant proposes 11
to address the principles outlined in the strategy. 12
Now I would like to discuss waste 13
categories. The first is the low and intermediate 14
level waste. They are generally the same for each 15
reactor type; there may be some minor differences but 16
generally they are the same. 17
Examples of low level waste which 18
includes paper, rags, tools, clothing, filters, et 19
cetera, basically these -- the low level waste primary 20
processing is to reduce the volume often by compaction 21
or incineration. Typically low level radioactive 22
waste produces approximately 90 percent of the volume 23
of radioactive waste but it has only 1 percent of the 24
radioactivity. 25
72
An example of low level waste storage 1
is shown in Photo 1. Low level waste generally 2
requires little to no shielding. 3
Intermediate level waste contains 4
higher amounts of radioactivity and requires shielding 5
as shown in Photo 2. Typically intermediate level 6
waste comprises resins, chemical sludges, et cetera. 7
Seven (7) percent of the volume of radioactive waste 8
produced is intermediate level waste but it has only -9
- it has 4 percent of the radioactivity. 10
The waste management plan, as I 11
discussed in my previous slide, should identify the 12
possible waste streams and the types of waste that 13
will be produced in each stream. An estimation on the 14
quantity of waste that will be produced will allow the 15
applicant to determine the type of enabling facilities 16
that will be required and the number of enabling 17
structures required as well. 18
The next category is used nuclear fuel. 19
A CANDU reactor design is well understood in Canada. 20
Used nuclear fuel, after leaving the reactor core, is 21
stored in water filled bays for approximately six to 22
ten years then transferred to dry storage. An example 23
of used nuclear fuel wet storage is shown in Photo 1. 24
Currently there is approximately one 25
73
and a half million used fuel bundles in wet storage 1
and close to 500,000 bundles in dry storage. 2
For the AREVA and Westinghouse-type 3
reactor designed the configuration of the nuclear 4
fuel, although different, as shown in Mr. Newland's 5
presentation from the CANDU reactor is different, the 6
storage technology is not much different than that 7
used for the current CANDU system. The major 8
differences of consideration would be in temperature 9
and criticality. 10
This is demonstrated by the example 11
that in France the used fuel in those reactors is 12
either based on uranium oxide slightly enriched with 13
uranium-235 or a mixture of depleted uranium oxide and 14
separated plutonium originating from spent fuel 15
reprocessing. 16
Interim storage structures have been in 17
use internationally for the past 20 years. In this 18
slide, Photos 1 and 2 are the OPG dry storage 19
containers and they are considered to be dual purpose 20
containers, namely storage and transportation. 21
Photos 3 and 4 are the cask storage 22
system used by many countries around the world. The 23
cask system is fixed canisters, similar to the AECL 24
design currently located at Point Lepreau and Douglas 25
74
Point. These have been in use internationally for 1
several decades. 2
All of these designs are based on the 3
multiple barrier concept or defence-in-depth. The 4
outer shell is concrete with an inner liner and then 5
the fuel stored inside. 6
Finally, my last slide is to talk about 7
the short- and long-term management of radioactive 8
wastes. The short- and long-term management of 9
radioactive waste produced is the responsibility of 10
the waste producer. The short term should include a 11
description on the interim management of all 12
radioactive waste pending final resolution or 13
disposition. 14
The long-term management should 15
describe the eventual disposition of the radioactive 16
wastes in the future. As I indicated earlier in 17
accordance with Regulatory Policy P-290, the long-term 18
solution should identify the measures needed to 19
prevent unreasonable risk to present and to future 20
generations from the hazards of radioactive waste and 21
should be developed, implemented and funded as soon as 22
practicable. 23
Thank you. 24
THE CHAIRMAN: Thank you very much. 25
75
I'd like to take this opportunity to thank all the 1
presenters for the information that you've given us 2
today. I think that information's been very useful to 3
us as we start on our journey trying to understand and 4
assess the impacts associated with the Bruce new 5
project. 6
Now what I would like to do is to offer 7
an opportunity to the panel members to ask questions 8
and we 9
-- I would like to start maybe with Moyra. And Moyra, 10
if you have any questions, go ahead. I would say you 11
should hold them to about five to start off with. And 12
then we'll go around and see. 13
14
2. Questions from Joint Panel Members 15
16
MEMBER McDILL: Thank you, Mr. Chair. 17
Because all three presentations were 18
presented together it gives me an opportunity to 19
collect a few questions into one. I'd like to start 20
with a general question on the footprints required -- 21
excluding cooling technologies, cooling towers or 22
once-through -- for the three types of reactors to 23
produce roughly the same megawatts electrical. So in 24
terms of the ACR-1000, APR and the AP1000, in terms of 25
76
relative required sizes? 1
MR. SCHWARZ: Thank you. Garry Schwarz 2
for the record. 3
Basically the largest reactor, the EPR, 4
does have the largest footprint followed by the ACR 5
followed by the AP1000 in relative sizes although we 6
can't give you the exact dimensions here today but on 7
a relative basis. 8
MEMBER McDILL: Thank you. 9
And with respect to the containment, 10
two are concrete with steel -- stainless steel liners. 11
The AP1000 is slightly different, the -- there is a 12
steel construct underneath. Is that structural steel? 13
MR. NEWLAND: Dave Newland for the 14
record. 15
Yes, I believe so. 16
MEMBER McDILL: Thank you. 17
My second question relates to the 18
differences in the amount of slight enrichment and I -19
- this is going to be a sort of a broad question. I 20
wonder if you could discuss the difference in -- the 21
relative difference in emissions; the -- if there's 22
any difference in the length of in-pool fuel cooling, 23
in terms of years; and the differences, if any, in the 24
requirements for dry storage after pool cooling? 25
77
MR. SCHWARZ: Garry Schwarz for the 1
record. 2
We'll take that question under 3
advisement and get back to the panel on it as we're if 4
I understand correctly, what you’re really getting at 5
is, okay, you take the fuel out of the reactor and put 6
it into the spent fuel storage base; what’s the 7
duration that it has to remain there for the more 8
highly enriched versus the lower-enriched fuel before 9
you can transfer it into dry storage, and are there 10
then any implications and in terms of dry storage for 11
the different enrichments. 12
MEMBER McDILL: Thank you. Yes, 13
please. 14
MR. SCHWARZ: Mr. Chris Harwood will 15
provide some information. 16
MR. HARWOOD: Chris Harwood, for the 17
record. 18
The length of time in storage will 19
depend quite a lot on the final burn-up of the fuel as 20
how long it’s been in reactor and the EPR on the 21
AP1000 burn their fuel up rather more. They’re higher 22
enrichments, but they also burn the fuel more. 23
They’ll need longer in storage before they can be 24
moved but, as for times, we’ll have to get back to 25
78
you, as Garry said. 1
The maximum burn-up for ACR fuel is 2
24,000 megawatt-days per tonne of uranium. 3
MEMBER McDILL: Sorry, could you repeat 4
that? 5
MR. HARWOOD: Twenty-four thousand 6
(24,000) megawatt-days per tonne of uranium, and for 7
AP1000 it’s 60,000, and for EPR it’s 62,000. 8
MEMBER McDILL: Thank you. 9
With respect to refuelling, what 10
fraction of the core is refuelled for the EPR and the 11
AP1000 at each outage and how long -- I realize 12
there’ll be maintenance going on -- but with respect 13
to the refuelling, how much of the outage is related 14
to refuelling? 15
And maybe in general terms, you could 16
compare that to the online fuelling that’s used for 17
the ACR-1000. 18
MR. SCHWARZ: Chris Harwood will 19
respond to that, please. 20
MR. HARWOOD: Chris Harwood, for the 21
record. 22
I think it’s about one-third is 23
refuelled. If that’s wrong, we’ll correct it. 24
MEMBER McDILL: And do you know the 25
79
length of the outage associated with the refuelling? 1
MR. NEWLAND: An outage, I think best 2
practice for PWRs is around 16 days. What percentage 3
of that is for refuelling specifically? I don’t know, 4
but we can get back to you. 5
MEMBER McDILL: Thank you. 6
My fourth question relates to the 7
ability for passive, natural cooling. The AP1000 -- 8
correct me if I’m wrong or perhaps assist me in asking 9
the question -- but the AP1000 appears to have passive 10
natural cooling. I’m not sure about the EPR because 11
it wasn’t suggested. 12
Does the ACR-1000 have the ability to 13
thermal cycle in the event that there’s a complete 14
failure of power from the grid as well as failure of 15
back-up power? 16
So in terms of the three reactor types, 17
if there’s a complete failure of power from the grid 18
and back-up power for whatever reason, what’s the 19
capability for natural cooling? 20
MR. HARWOOD: Chris Harwood, for the 21
record. 22
I think the AP1000 has water supplies, 23
I think, for at least 72 hours. The ACR and the EPR, 24
once they’ve poured away the secondary coolant 25
80
inventory, they do need electrical power. 1
I’m not quite sure how long they can 2
survive without any power, but they do have on-site 3
power, off-site power, emergency diesels and station 4
blackout diesels, so it’s a pretty low likelihood 5
event. 6
MEMBER McDILL: I realize it’s a long 7
way down the power food chain. 8
My final question in this round relates 9
to dry storage, and I realize there’s a slight 10
difference between the various methodologies, but with 11
respect to the use of the enriched fuels and the dry 12
storage containers, do both the EPR and the AP1000 13
currently use dry storage similar to Point Lepreau and 14
Gentilly-2. Is that correct? 15
MR. HOWARD: Don Howard, for the 16
record. 17
Yes, I think from the slide that I 18
presented showed the canister-type container which is 19
similar to what is currently the design in use at 20
Point Lepreau and Douglas Point. Gentilly-2 uses what 21
is a variation of that called a MACSTOR system, which 22
is a modular-type storage, but similar with the inner 23
liners with the baskets. 24
In this design -- is that the fuel is 25
81
going to be placed either vertically or horizontally 1
inside a liner which is then encased around by 2
concrete, which is similar to the AECL kind of CANSTOR 3
system and is stored outside as well. 4
MEMBER McDILL: And I assume there is 5
necessary drying and that sort of thing for -- so 6
there’s no percolation through to the surface as there 7
might have been in previous CANDU draft designs? 8
MR. HOWARD: Could you repeat that 9
question, please? 10
MEMBER McDILL: Perhaps I should leave 11
it for another round. Thank you. 12
I think that’s my five, Mr. Chair. 13
MEMBER HARVEY: Merci, Monsieur 14
Président. 15
My first question more touches that 16
point, but about the ACR-1000 containment building, 17
will that containment building, which is similar to 18
what does exist with the Canadian fleet, is it just a 19
copy of that containment building or something else? 20
MR. NEWLAND: Dave Newland, for the 21
record. 22
I would say that it is similar to the 23
existing CANDU-6 containments, but it’s probably more 24
robust in terms of protection against external events 25
82
and aircraft crash. 1
MEMBER HARVEY: So it wouldn’t be a 2
copy or something that we can compare to the other 3
type of containment building for other technology? 4
MR. NEWLAND: Dave Newland, for the 5
record. 6
You could make comparisons with, for 7
example, the CANDU-6 technology. It is similar. It 8
has a concrete shell. It would have a similar steel 9
liner to a modern CANDU-6. 10
MEMBER HARVEY: But more robust, that’s 11
what you said. Because during your presentation, you 12
mentioned that for one -- I don’t remember if it was 13
the AREVA or the other one -- that was able to sustain 14
a crash and you mentioned it just for one, so my 15
question has to do with the capacity of the others to 16
resist a crash. 17
MR. NEWLAND: Dave Newland, for the 18
record. 19
So all of the containment designs are 20
specifically designed against all external events 21
including the crash of a large aircraft. 22
MEMBER HARVEY: Thank you. 23
You have mentioned in all the 24
presentations, the passive security systems. 25
83
First question is the -- first part of 1
my question is there was a passive security system 2
because you mentioned once that if there is a problem, 3
there is a signal, so all those systems depend from a 4
signal coming from somewhere. 5
Am I correct to think like that; that 6
even if we call it passive, well it needs a signal to 7
operate. Is that the --- 8
MR. NEWLAND: Dave Newland for the 9
record. 10
I would say that in the first instance 11
when there is an unwanted or an upset condition or the 12
initiation of event, there will be a trip signal that 13
will come in. So there is that signal, if you like, 14
for systems, for the trip of the shutdown system. 15
The extent to which that signal will 16
then activate other equipment varies on the type of 17
equipment and it varies from design to design. So 18
some of those equipment or systems, for example the 19
accumulator tanks, are completely and totally passive. 20
So you really have to look to the 21
details of the specifics of the design and the 22
technology and it will vary accordingly. 23
MEMBER HARVEY: What -- I don’t want to 24
answer my question but those signals, where do they 25
84
come -- they come from many -- I know there is many 1
monitoring devices everywhere in the reactor station. 2
But what is the part played by the control room in 3
that? What is the automatism and the manual operation 4
of those things? 5
MR. SCHWARZ: Garry Schwarz for the 6
record. 7
Basically, the initial actions are all 8
fully automatic. Fundamentally, the new designs, for 9
example the Canadian designs, there's no credit to be 10
taken for operator action in the first 15 minutes. I 11
know in some of these other designs there is no credit 12
for operator action to be taken for the first 30 13
minutes. 14
So those actions by the instrumentation 15
are all automatic. So one thing you have to remember 16
with the -- even with the passive designs, typically, 17
as Mr. Newland said, the action kicks off with 18
something that is initiated by the instrumentation. 19
The pressure is too high, water level is too low, or 20
something like that. Okay? 21
So the system operation kicks off with 22
that but once it has done that, perhaps opened the 23
valves that need to be open, then the rest of the 24
action is a passive type of an action. In other 25
85
words, the water flows from the tank and it 1
establishes thermo-syphoning or whatever the mode will 2
happen to be to continue the cooling for a period of 3
time. And that's typically the way that these systems 4
work. 5
The one design that we were looking at, 6
the Westinghouse design, happens to have incorporated 7
some unique passive features in that haven’t existed 8
in most other designs before. 9
MEMBER HARVEY: What do you mean when 10
you say there is no credit given in the first 15 11
minutes? For example, I saw that in the -- in some 12
documents yesterday and sometimes it's 30 minutes, 13
sometimes it's 50 minutes, and what does it mean? 14
MR. SCHWARZ: What it means is that the 15
operator sits there with his hands behind his back for 16
the first 15 minutes and does nothing. That is the 17
way that the system, the station has to be designed. 18
So basically, the operator can sit back 19
like this. He is supposed to be able to sit there and 20
just think about what's going on and look at the 21
panels and so on and try to understand what's 22
happening. 23
There's no pressure on him to have to 24
take any action within that first period of time. So 25
86
it's there to in fact give the operator the time to 1
think about, to look in his -- to observe what 2
information is coming on the panels and then from that 3
information to say, “It looks like this is what's 4
happening. Let me go into my emergency procedures or 5
my abnormal response procedures and see what the 6
appropriate action is after that time.” 7
MEMBER HARVEY: Okay. My next question 8
has to do with the four quadrants or four trains. At 9
least two of the technologies use that configuration. 10
What I would like to know is, in those 11
quadrants, those trains, what type of equipment is 12
there because when looking at the presentation, most 13
of the equipment is inside the containment building. 14
And what is in those quadrants and what is the nature 15
of the equipment and monitoring devices that are 16
there? And are the equipment used for normal 17
operation all of that equipment or there is 18
redundancy? 19
MR. NEWLAND: Dave Newland for the 20
record. 21
The kinds of systems that are in those 22
four quadrants are: electrical supplies, so essential 23
electrical supplies; essential water supplies; and the 24
long-term cooling system which is part of the 25
87
emergency core cooling system. 1
So they are -- for example, those 2
systems, the electrical ones and the water supplies, 3
are supporting systems for the other systems that are 4
in containment. So the majority of the key safety 5
systems, shutdown systems, the ECC systems and all of 6
those systems that are required in the event of a 7
severe accident, for example, all reside within 8
containment. 9
So it's really the support systems, 10
plus the long-term cooling system. 11
MEMBER HARVEY: When you say support 12
system, this would say that they are not normally 13
operating or...? 14
MR. SCHWARZ: Garry Schwarz for the 15
record. 16
They may be normally operating but what 17
you would have is you would have trains of water 18
supply like you’d have pumps replicated from the one 19
quadrant to the other quadrant. So wherein in the 20
plant that you see today, you may see that you would 21
have a number of pumps. Let's say that you need two 22
operating normally, you might have four. So two would 23
be a backup but what they would do in this particular 24
situation is they would, say, distribute them among 25
88
the four quadrants and you might have a pump per 1
quadrant. Or sometimes what will happen is you'll 2
have some amount of backup within a quadrant but then 3
you've got quadrants backing up quadrants. 4
The whole idea behind this kind of a 5
concept is to have a lot of separation and 6
independence so that if you have some event happening 7
in one quadrant like a fire or something like that, it 8
will not spread to the other quadrant and take that 9
loop out as well. 10
So therefore, it gives you a lot more 11
reliability, for example, of your heat sink 12
capability, in other words your cooling capability, a 13
lot more reliability for your electrical supplies, and 14
even instrumentation and control because you will have 15
some coming out of each of the different quadrants. 16
So that's what behind this. It's 17
really there as a defence mechanism against what we 18
call common mode events, cross-links and that kind of 19
thing. 20
MEMBER HARVEY: But if I'm correct, 21
Westinghouse technology is not configurated that way. 22
Am I correct or I miss something? 23
MR. NEWLAND: Dave Newland for the 24
record. 25
89
Yes, that’s fair to say. The 1
Westinghouse design is really quite different. It 2
doesn't rely to the same extent on, if you like, 3
active systems. It relies more on passive systems 4
which are considered to be very, very reliable. 5
But nevertheless, where you really 6
require that -- an active component to be active, then 7
it may be duplicated or more in order to provide that 8
high level of reliability. It's, if you like, a 9
different design philosophy. 10
MEMBER HARVEY: Merci (inaudible) au 11
micro. 12
THE CHAIRMAN: Okay, well, before we go 13
back to Moyra, I'd like to ask one or two questions, 14
and the first one relates to the water cooling towers. 15
The numbers that you gave for the 16
amount of 200 m3/s, that relates to one unit? So if 17
you had five units or four, would you need the same 18
amount of water or could you use less? 19
MR. McKEE: Those numbers related to 20
the Canadian stations and those are at the -- some of 21
those are supplying more than one reactor unit. 22
THE CHAIRMAN: So is my answer 200 m3/s 23
for one reactor, three reactors, five reactors the 24
same? 25
90
MR. McKEE: No. For example, if we go 1
to Darlington with 1 to 4 units, we're looking at 2
roughly 12 million cubic metres per day, whereas 3
single units come in around at times 2 to 5. 4
So it depends how many units a flow-5
through system is supporting. 6
THE CHAIRMAN: So it's not an 7
exponential number? There's a factoring in there, is 8
there? 9
MR. McKEE: I can get the specific 10
information for you later. I don't have that 11
immediately at hand. 12
MR. WISMER: The number you were given 13
is for four units because that's typically what's 14
operating at the Canadian reactors. So you want to 15
now per unit, just divide it by four. 16
THE CHAIRMAN: Okay. So it's 50 cubic 17
--- 18
MR. WISMER: Yeah, sorry, Don Wismer. 19
That's correct. 20
THE CHAIRMAN: The other question I had 21
is quite similar. 22
If you had one reactor with two banks 23
of towers that are the mechanical towers, would you 24
need two banks for each reactor or can the reactors be 25
91
pooled or on the same bank, for example? 1
MR. WISMER: I'll have to get back to 2
you on that question. We don't have a lot of 3
experience in Canada with the tower designs because 4
all ours are once-through right now, so --- 5
THE CHAIRMAN: And I guess my follow-up 6
question is, would the noise factor be expanded by an 7
exponential factor of five if you were to increase the 8
banks to five? 9
MR. McKee: The noise factor would be 10
strongly influenced by the individual placement of the 11
different banks in the local geography associated with 12
the placement. So I don't think you could quite 13
simply make it a multiplicative factor. 14
MR. SCHWARZ: Mr. Chairman, with 15
respect to that last item, I think that in some 16
respects you might -- the Panel might need to ask the 17
applicant the question. 18
But if I may just state that if you 19
have two units and for reliability reasons for 20
operating the units, you might not want to rely on one 21
single bank of cooling towers because if they're out 22
of service then both of your units are out of service. 23
So you can get into reliability issues. 24
So it would be very much design specific. It doesn't 25
92
mean that they can't design their way around that 1
particular issue by allowing a half a bank or 2
something to be out at one time while they're 3
maintaining the other during an outage of a unit, but 4
you get into those kind of issues. 5
So it might be an interesting question 6
that you may wish to pose to the applicants. 7
THE CHAIRMAN: My final question 8
relates to the questions that were posed a while ago 9
by my colleagues. 10
Given that you have a major power 11
outage both in-house and the grid, the system goes 12
blank. Your answer was that the operator sits and 13
watches the clock, the dials, but if there's no power 14
going to the dials, what happens? Is there a battery 15
back-up or how is the system supplied? 16
MR. SCHWARZ: Yes, there is a battery 17
back-up there to provide emergency power for some 18
period of time, something to the order of around an 19
hour. But for the modern plants you have to consider 20
that if you lose off-site power -- all off-site power, 21
and then they still have basically emergency 22
generators -- well, first line of defence may be 23
standby generators and then they're followed by what 24
we call emergency generators. 25
93
So basically two lines of defence and 1
after that you still have battery back-up for a period 2
of time which allows you to get one of these other 3
sources back on line. So you have a number of 4
defences to prevent you from getting into a situation 5
where you are absolutely cold in the water; in other 6
words, you have no power whatsoever. 7
THE CHAIRMAN: I thank you. 8
I was just thinking if a -- because I 9
heard it this afternoon -- if a plane crashed into the 10
unit and knocked the local generators out then the 11
power grid at the same time. 12
MR. SCHWARZ: Oh, that's a very good 13
question. The design is to be such that irrespective 14
of the direction of the aircraft crash, we'll always 15
have a source of power available inside the station. 16
That's one of the reasons why they tend to go to 17
something like a four quadrant design and you will see 18
if you look back on the -- some of the drawings in 19
terms of the site layout of the buildings, you will 20
see that they've got standby generators over here on 21
one side of the reactor building, and way other there 22
they've got another set of standby generators sitting. 23
And the reason for that is to avoid them both being 24
knocked out simultaneously by an event such as an 25
94
aircraft crash. 1
MEMBER McDILL: Thank you, Mr. Chair. 2
I'll retry my last question with a little bit more 3
thought put into it. 4
My question is, with respect to fuel 5
removed from the pool and the use of dry storage, are 6
the basic steps the same in terms of drying, 7
evacuating the DSC for example or the canisters, seal 8
welding, packaging, largely the same? 9
MR. HOWARD: Don Howard, for the 10
record. 11
Yes, I would say that is correct in 12
that they're similar in that once the fuel is removed 13
and placed into containers, vacuum dried, seal welded 14
with a helium inner environment inside. 15
So similar to what is currently used at 16
OPG, yes. 17
MEMBER McDILL: Thank you. My next 18
questions are a little more specific and perhaps I'll 19
give you a page references. 20
With respect to the reactor pressure 21
that’s on page 26, the EPR shows that there are -- 22
there's a space for irradiated samples for testing for 23
brittle failure. 24
Is that unique to the EPR? And maybe 25
95
you could just elaborate on that a little, please? 1
MR. NEWLAND: Dave Newland, for the 2
record. 3
I can't answer the question as to 4
whether that's a new feature. Certainly, in terms of 5
reactor pressure vessel design, more generally there 6
has been a move away from welded technology, 7
especially around the core barrel region, to avoid 8
those kinds of problems, the fluence and their 9
interaction with the welds. 10
But with respect to the level of 11
surveillance, we can get that information for you. 12
MEMBER McDILL: Okay, thank you. 13
My next question relates to page 28 and 14
the potential borate for the reactor. Is that system 15
pressurized; on page 28? And then again for the 16
AP1000 I believe it was a little clearer. The 17
reference for the EPRs, there's an extra borating 18
system but it's not clear whether it's -- how it's 19
activated. 20
MR. NEWLAND: Dave Newland for the 21
record. I'll ask Chris Harwood to respond to the 22
previous question and then to respond to the question 23
you've just asked. 24
MEMBER McDILL: Thank you. 25
96
MR. HARWOOD: Yes. In terms of the 1
samples in the down corner region, because weld 2
embrittlement has always been a concern with reactor 3
pressure vessels, I think manufacturers have always 4
included samples in that area. They can remove them 5
during outages and see how much embrittlement, see how 6
much fluence the materials have received. So yes, 7
it's common practice. Although I don't have any 8
specific information on the Westinghouse design, I 9
would be very very surprised if they don't include 10
samples in that region as well. 11
So to move to the other question, the 12
extra borating system in the EPR, that's driven by a 13
positive displacement pump. In the AP1000, borated 14
water is contained in the core make-up tanks and in 15
the accumulators, and in the in-containment refuelling 16
water storage tanks. So whichever way water gets into 17
the core, it's borated water. 18
MEMBER McDILL: Thank you. 19
With respect to the AP1000, there's a 20
note that it uses an advanced Zirlo alloy. Do you 21
have any information on what makes it special? 22
MR. NEWLAND: Dave Newland for the 23
record. 24
No, I can't, but we can get you the 25
97
information. 1
MEMBER McDILL: And a similar question: 2
what makes this particular method of -- the 17 by 17 3
standard but it's specified to being debris resistant. 4
What is that particularly makes it debris resistant 5
when compared to something else, some other method? 6
MR. NEWLAND: Dave Newland for the 7
record. 8
I don't think that there is significant 9
difference between the Westinghouse and the EPR design 10
with respect to those kinds of features. So, for 11
example, that fuel I believe is already used in at 12
least two other plants in Europe. So it's not 13
particularly new but it incorporates, if you like, 14
modern-day features with respect to debris resistance, 15
and I would expect those kinds of features to appear 16
in any modern-day light-water reactor fuel. 17
MEMBER McDILL: Thank you. 18
My next question is: with respect to 19
plume abatement technologies, presumably there is some 20
cut-off temperature at which that plume abatement 21
becomes ineffective. Can you elaborate on that? 22
MR. McKEE: No, I'd have to get -- 23
anything on the engineering end I'd have to get backup 24
on. 25
98
MEMBER McDILL: Thank you, Mr. Chair. 1
THE CHAIRMAN: Mr. Harvey. 2
MEMBER HARVEY: Merci. 3
You said that the new ACR1000 is more 4
compact than the previous one -- previous CANDU. What 5
does it mean? What is more compact? Is it just the 6
calandria or other elements of the system? 7
MR. NEWLAND: Dave Newland for the 8
record. 9
In the context of that particular 10
remark I was referring to the lattice pitch between 11
the fuel channels, namely the reduction from a 28-12
centimetre to pitch to 24 centimetres. So in that 13
context it's specifically to do with the calandria. 14
MEMBER HARVEY: The fact that the 15
Westinghouse technology seems to be -- well, it's a 16
simple one, and there is less elements in that 17
technology, at least when we see it on your slides -- 18
less parts. Does it make a big difference in the -- 19
for the maintenance for the -- or the waste for the -- 20
I'm thinking of low-level waste. Does it make a big 21
difference, the fact that there is less parts in a 22
technology than another one. 23
MR. NEWLAND: Dave Newland for the 24
record. 25
99
I can't give you a detailed answer but 1
quite clearly, where you have less active components, 2
then that requires less maintenance. It was part of 3
the design philosophy of Westinghouse to go to, I 4
believe, basically a simpler kind of a system, one 5
that is more reliant on passive features rather than 6
active features. And I guess a corollary to that is 7
that there is less maintenance to do on those active 8
features because they don't exist. 9
MEMBER HARVEY: Does that also mean 10
that there is less persons -- I mean, it needs less 11
resources to operate the reactor; human resources. 12
MR. SCHWARZ: Garry Schwarz for the 13
record. 14
I wouldn't say that it necessarily 15
translates into many less people that you need to be 16
there to operate the facility. You have to remember 17
that the majority of the people that you need in a 18
facility to operate, it deals more with secondary-side 19
plant than it does with primary-side plant. So the 20
secondary side is about the same in any of these 21
plants. In other words, the conventional side of the 22
plant we have the turbine generator, so the feedwater 23
systems and so on are all basically still the same as 24
what you have on -- it's pretty uniform across these 25
100
plants. 1
So that aspect doesn't change, and you 2
need people for emergency response capability and so 3
on, so that doesn't change that much. But typically, 4
like TWR plants, when they're normally running you 5
don't have people going in -- ducking in and out of 6
containment much anyway. So I don't think you're 7
going to see that much of a difference in terms of the 8
number of operating staff that you have. 9
It could influence though -- because, 10
as Mr. Newland said, you've got less equipment to 11
maintain and so on, so it could influence though the 12
number of maintenance people that you need or the 13
number of maintenance hours that you spend annually on 14
a plant, so that's where you could have some savings. 15
But again, this is a new design, and even though it's 16
simpler we don't have any experience with it, so you 17
have to keep these things in mind. 18
MEMBER HARVEY: What about the waste? 19
Mr. Howard told us that it was almost the same thing 20
for the three technologies. What about low-level 21
waste? 22
MR. HOWARD: Don Howard for the record. 23
Are you speaking about generation of low-level waste 24
or storage? 25
101
MEMBER HARVEY: Yes, generation. 1
MR. HOWARD: Because I think in my 2
comment what I meant was to say that for the storage 3
methods that -- once the low-level waste is produced, 4
the storage is pretty much similar. As far as 5
generation of waste, I guess a number of factors would 6
affect the volumes of low-level waste that you would 7
generate, based on minimization programs that you 8
would have in place, outages and maintenance programs 9
and things of that nature. So that would affect the 10
volumes of low-level waste that you would produce from 11
the various designs. 12
As far as exact numbers, I don’t have 13
any right now to provide, but I can look those up and 14
provide that information to you. 15
MEMBER HARVEY: About the -- I’m coming 16
back on the security systems, such system has to be 17
verified from time to time, so what is the normal 18
procedure to be sure that those systems will operate 19
if there is any critical event? 20
MR. NEWLAND: Dave Newland for the 21
record. 22
I guess the first thing I would say is 23
that at the start up of the plant, there is a thorough 24
commissioning program to ensure that all of the 25
102
systems will meet their design requirements. 1
For most systems, for most components, 2
there is a means of verifying online that they will 3
perform as required as designed, so there will be a 4
certain testing frequency and there will be certain 5
criteria which must be met during those tests. 6
One of the reasons for moving to a 7
four-quadrant system or approach, should I say, is 8
that it allows you to take one of those quadrants or 9
certain systems in that quadrant offline and do 10
testing and do maintenance without there being an 11
outage. 12
So yes, there is regular testing to 13
ensure that safety systems will operate as designed. 14
MEMBER HARVEY: What makes a difference 15
in the power? Is it just the quantity of fuel in a 16
reactor that makes, for example, AREVA more powerful 17
than Westinghouse or CANDU? Is it just the quantity 18
of fuel in the reactor? 19
MR. HARWOOD: Chris Harwood for the 20
record. 21
Yes, the power is almost totally 22
reliant on the amount of fuel that’s in the AREVA as -23
- let me check my notes here. 24
MEMBER HARVEY: I checked that the 25
103
quantity and for me, it appears like that but I don’t 1
--- 2
MR. HARWOOD: It has 241 fuel 3
assemblies 4
--- 5
MEMBER HARVEY: Yes. 6
MR. HARWOOD: --- compared with the 7
AP1000’s 157, but the fuel is rated pretty much the 8
same. In fact, the ACR as well, the maximum rating on 9
any fuel element is very much the same so it’s really 10
the quantity of fuel that makes the difference. 11
MEMBER HARVEY: Monsieur Président. 12
THE CHAIRMAN: Thank you; merci. 13
I have a question relating to the rod-14
control assembly in the EPR. What’s the major 15
function of the control assembly? 16
MR. NEWLAND: Dave Newland for the 17
record. 18
Both the EPR and the Westinghouse 19
designs rely on the reactor control cluster assemblies 20
for the control of power, the control of flux 21
distribution in the core and they also act as a 22
shutdown system if there is a need to trip the 23
reactor. 24
THE CHAIRMAN: Now, by shutdown system, 25
104
one unit could be shut down and the rest could work? 1
MR. NEWLAND: Those assemblies act in 2
unison so there would be one signal that would go to 3
all of those units and they would release a magnetic 4
clutch and all of the rods drop in. 5
THE CHAIRMAN: My other question 6
relates to the plume mitigation program. I’m not so 7
sure if it’s not the same question that Moyra asked, 8
but the question is; do you have information on the 9
temperature profiles that require mitigation of the 10
plume? 11
MR. McKEE: Is this an aquatic 12
discharge plume or an atmospheric? 13
THE CHAIRMAN: In the atmosphere, if 14
you have a temperature of -5 or -25, when does the 15
mitigation -- when are you required -- you mentioned 16
in Europe, they do have mitigation programs. 17
MR. McKEE: The plume mitigation 18
referred to there was with the hybrid tower design 19
where it’s built in and the issue with -- that 20
functions continuously so you’re using both cooling 21
systems for the cooling and one of the benefits is the 22
plume mitigation. 23
THE CHAIRMAN: Thank you. 24
MEMBER McDILL: Thank you very much. 25
105
With respect to cooling systems again, 1
could you repeat, please, the statistics for how many 2
NPPs are using cooling towers? I think you said 47. 3
And then how many coal-fired are using -- it’s on page 4
9, I believe, that you said it. I’ll find it. 5
MR. McKEE: Malcolm McKee for the 6
record. 7
Those are for -- re-circulating systems 8
are used in approximately 47 percent of all U.S. power 9
plants, and that includes the large-scale plants for 10
coal and nuclear. And over the period from the mid-11
1990s up until around 2003, all coal-fired facilities 12
-- 88 percent of all coal-fired facilities were using 13
re-circulating. 14
MEMBER McDILL: Do you have any sense 15
of what the equivalent numbers are for, say the, E.U. 16
or European reactors and power plants? 17
MR. McKEE: Malcolm McKee for the 18
record. 19
I have a breakdown for -- I don’t have 20
the numbers for the E.U. as a whole. I do have a 21
breakdown for reactors in France and Germany. 22
In France, we’re looking at 19 stations 23
with eight once-throughs, 10 towers and one combined, 24
and in Germany, we have 13 stations -- these are all 25
106
multiple-unit stations or predominantly, five once-1
through, eight towers, two combined and two hybrids. 2
MEMBER McDILL: Do you have any sense 3
of how the various communities have -- how the various 4
builders have gone about educating or explaining to 5
the communities in which they’re building how cooling 6
towers work and are used? I know, I’m asking you to 7
reach across the ocean today so --- 8
MR. McKEE: Malcolm McKee for the 9
record. 10
No, not offhand of the actual 11
information programs. 12
MEMBER McDILL: On page 25, you cited 13
some U.S. regulations. What are the equivalent 14
Canadian -- I would assume CEAA -- regulations in that 15
area? 16
MR. McKEE: Malcolm McKee for the 17
record. 18
Presently, issues related to water 19
withdrawal are predominantly handled by provincial 20
licence permits with expectations of certain 21
temperature regimes being achieved within the 22
receiving environment with thermal discharge. 23
The handling of impingement entrainment 24
issues have tended to vary and not receive as much 25
107
attention as the thermal discharge issues. 1
MR. WISMER: Okay, I'm Don Wismer. 2
We've been speaking with the federal authorities on 3
these two issues. Environment Canada is thermal, and 4
Fisheries and Oceans is intake fish loss. And as far 5
as -- which is entrainment and impingement. 6
As far as that goes, the Department of 7
Fisheries and Oceans is just now developing a draft 8
policy on that. So it's not final yet. On thermal 9
effects with Environment Canada, it seems to be a 10
site-specific approach based on the likelihood of 11
population level risk. 12
Under our Act we like to see best 13
available technology as a requirement. 14
MEMBER McDILL: And what is the current 15
best available technology? 16
MR. WISMER: Well, the current best 17
available technology in terms of existing facilities 18
is what we've seen at Darlington with the intake and 19
the diffuser. That was a 1980s design. So there are 20
probably features that could be added to make it a bit 21
more effective, but that's the basic design with a 22
once-through cooling system. 23
MEMBER McDILL: Is that form of design 24
used in some of the US NPPs, for example? 25
108
MR. McKEE: I'm not aware of the 1
specific intake design being used at any other sites 2
other than at Darlington -- the non-porous design -- 3
though there are a wide range of intake mitigation 4
technologies that are now recognized by the EPA. 5
There's about 11 different technologies 6
associated with it. Some of them involve the actual 7
intake itself and some of them involve modification 8
and mitigation on screens and before the intakes, 9
et cetera. 10
MEMBER McDILL: Thank you, Mr. Chair. 11
THE CHAIRMAN: Thank you. 12
MR. HARVEY: The new CANDU will operate 13
at a higher temperature than the previous one, which 14
is 210 degrees. How much is the increase and does it 15
make a difference for cooling water releases, meaning 16
will the cooling water also be a higher degree than 17
the previous one? 18
MR. NEWLAND: Dave Newland, for the 19
record. I don't think that that higher temperature 20
translates directly to higher temperatures in the 21
cooling water. I think there are a number of other 22
factors that you have to consider in terms of the 23
efficiency of the secondary cycle. 24
So at this point in time we don't have 25
109
the information with respect to the discharge 1
temperatures but we could no doubt get that if the 2
Panel is interested. 3
MEMBER HARVEY: Yes, I think we are. 4
Light water versus heavy water; what are the 5
advantages and disadvantages using the heavy water or 6
not? Is there any -- about the security or the waste 7
characteristic? I mean does it make a difference? 8
Could just elaborate on that point? 9
MR. SCHWARZ: Well, from a radiation 10
protection point of view, eliminating the heat 11
transport system from utilizing heavy water is 12
certainly a plus because most of the leaks in the 13
current power stations tend to be more from the heat 14
transport system than from the moderator system; 15
although in fact that's one of the reasons why you try 16
to keep the tritium level down in heat transport 17
systems and you have things like tritium removal 18
systems to help to do that. 19
So from a radiation protection point of 20
view it will -- should lower the tritium dose on a 21
plant having no heavy water in the heat transport 22
system. 23
MEMBER HARVEY: Again on the security 24
aspect, if both security systems operate - and I'm 25
110
talking of the rod and the poison, everything -- does 1
the condition stay like this for a long period of time 2
or do you need other systems to -- for the long-term 3
preservation of the -- in order that the security 4
remains the same on the long-term period? 5
In other words, do you have something 6
to do -- something else to do to get the station 7
secure? 8
MR. NEWLAND: Dave Newland, for the 9
record. Once the reactor is shut down there are 10
normally passive systems that will relieve the heat 11
transfer from the fuel on a very, very long-term 12
basis. So you could probably leave it for, for 13
example, days on end without any operator 14
intervention. 15
Obviously at some point operators will 16
need to do something but the systems are designed so 17
that operator intervention is not required on an 18
immediate basis and allows for very lengthy operator 19
interventions. 20
THE CHAIRMAN: Thank you. When you 21
poison the system, how long does it take to stop and 22
how long does it take before you can restart it? 23
MR. NEWLAND: Dave Newland, for the 24
record. To fully take out the poison from the 25
111
moderator system it's about 48 hours; 48 hours, yes. 1
THE CHAIRMAN: And there were two parts 2
to it. How long does it take the reactor to shut down 3
once you poison it? 4
MR. NEWLAND: Dave Newland, for the 5
record. For the poison system, probably around one 6
second. 7
THE CHAIRMAN: Thank you. Moyra. 8
MEMBER McDILL: On page 9 of the 9
technologies handout there's the picture of the 10
CANFLEX fuel bundle with the 43 elements. What's the 11
approximate size of this bundle compared to the 12
current bundles? 13
There is fortunately a size for the 14
other fuel bundles, so how big is this? 15
MR. NEWLAND: Dave Newland, for the 16
record. I believe it's exactly the same length as a 17
37-element fuel bundle, so one and a half metres. 18
With respect to the diameter I'm not sure. 19
MEMBER McDILL: Thank you, Mr. Chair. 20
That's it. 21
THE CHAIRMAN: That's it. 22
MEMBER HARVEY: It might be the last 23
one. 24
My question has to do with the 25
112
Darlington system, the cooling system. It has been 1
there for quite a period of time and does that system 2
present some problem in its maintenance or in the 3
deficient part of it? Is it quite a reliable system 4
and do you have any information about the performance 5
of that system since it has been installed? 6
MR. WISMER: It’s Don Wismer. 7
There's two parts to the system. At 8
the intake end, they didn’t foresee the zebra mussels 9
and so even though it's a 10-metre depth, they get 10
quite a coating of zebra mussels. So they have to 11
have quite an active cleaning program, giant vacuum 12
with divers on a barge, but it's managing the problem. 13
It hasn't affected operations. 14
At the other end, the diffuser end, the 15
only thing that can cause -- has caused D ratings in 16
the past is if they are starting to exceed their 17
provincial temperature limits, then they have to cut 18
back. But that's not an operational issue. It's 19
responding to the requirements put on them for 20
protecting the environment. 21
MEMBER HARVEY: If you compare that 22
system with the others, would you say that there is a 23
lot of advantage using it? 24
MR. WISMER: Yes. Don Wismer. 25
113
That's my view. There seemed to be a 1
lot less impacts with that system compared to -- 2
again, you’ve got to think of either end of the 3
system. For the discharge end, the diffuser is quite 4
a bit better than a shoreline discharge in terms of 5
really reducing impacts on the environment. 6
At the intake end, for the other 7
plants, we've got shoreline intake at Pickering. 8
We've got velocity caps offshore at Bruce and the 9
level of fish loss is a lot less with a Darlington-10
style intake where the picture we had was a little 11
hard to appreciate. But the intake is the size of a 12
football field and it's made of individual modules 13
about the size of one of our work stations each with 14
slots in the top and it reduces the velocity coming 15
into the intake to less than the swimming speed of a 16
small fish. So the number of fish that get sucked in, 17
it's order of magnitude or two orders of magnitude 18
less. 19
MEMBER HARVEY: Merci. 20
THE CHAIRMAN: Moyra, do you have any 21
additional questions? André? 22
I don’t either. So I think that ends 23
our session for today. Once again, we do want to 24
thank you very much. You did, during the afternoon, 25
114
promise to forward some additional information to us, 1
so we would be -- as soon as you get that information, 2
if you could forward it to the Secretariat and with 3
that, I thank you very much and I'm sure we'll see you 4
again someplace. 5
6
--- Upon adjourning at 3:49 p.m. / 7
L’audience est ajournée à 15h49 8
9
10
11
12
13
14
15
1
Technical Briefing on Reactor Technologies
Technical Briefing on Reactor Technologies
David NewlandDirector, Assessment Integration Division
May 7, 2009 E-Doc 3369879
David NewlandDirector, Assessment Integration Division
May 7, 2009 E-Doc 3369879
Canadian NuclearSafety Commission
Commission canadiennede sûreté nucléaire
nuclearsafety.gc.canuclearsafety.gc.ca
2
Introduction and OverviewIntroduction and Overview
• Purpose of the briefing• Outline
– Overview of ACR-1000 design– Overview of EPR design– Overview of Westinghouse AP1000 design– Cooling technology options– Waste management aspects
3
Purpose of BriefingPurpose of Briefing
• The purpose of the briefing is to provide the panel with an overview of some aspects of the three designs in the proponent’s project description
• The briefing focuses on aspects that are of relevance to the Environmental Impact Statement
• Information will include– principal features of the designs– key operational parameters– normal operation– control and mitigation of potential accidents
4
ACR-1000 1200 Mwe classACR-1000 1200 Mwe class
5
AECL ACR-1000 DesignAECL ACR-1000 Design
• The ACR-1000 is designed by Atomic Energy of Canada Limited (AECL)
• The design is based on the established CANDU horizontal pressure tube concept
• The design builds on proven engineering concepts of the established CANDU technology
• It uses heavy water as the moderator and light water as the coolant
• The fuel is of the CANFLEX 43 fuel element design• On-line fuelling
6
ACR-1000 Key ParametersACR-1000 Key Parameters
• Power: 3208 MW thermal, 1085 MW electrical (net)• Number of fuel channels: 520• Core diameter: 7.44 m• Regular horizontal lattice in a calandria• Moderator: heavy water• Heat transport system: light water• Fuel enrichment: 2.4% by weight• Outlet header operating pressure: 11.1 MPa• Outlet header operating temperature: 310 Celsius
7
Flow DiagramFlow Diagram
8
ACR Nuclear SystemsACR Nuclear Systems
9
10
ACR Reactor AssemblyACR Reactor Assembly
11
ACR-1000 4 Quadrant ApproachACR-1000 4 Quadrant Approach
• Safety and Safety Support Systems include single, duplicated or quadruplicated divisions to satisfy operational and safety considerations
• For single or two division systems, adequate redundancy is provided within each division to ensure that availability targets can be met in order to satisfy operational and safety performance requirements
• Selected 4-division systems achieve optimum safety and operational performance and reliability
• The 4-division systems are aligned with the 4 quadrant layout approach
• Inter-ties between divisions are provided as required to further enhance reliability and operational flexibility
12
ACR-1000 4 Quadrant ApproachACR-1000 4 Quadrant Approach
• Steel lined pre- stressed concrete containment
• Safety support systems in quadrants around reactor building
13
ACR-1000 Safety SystemsACR-1000 Safety Systems
• Control systems• Shutdown systems
– SDS 1: Shutoff rods– SDS 2: Poison injection into moderator
• Emergency core cooling system– core make-up tanks– accumulators– low pressure long term cooling system
• Emergency feedwater system
14
ACR-1000 Safety SystemsACR-1000 Safety Systems
• Containment– concrete with steel liner– containment isolation
• Systems that can mitigate against severe accidents– calandria– atmosphere control with passive spray– robust containment
• Safety support systems– reserve water– essential cooling water and service water– essential electrical power supplies
15
Shutdown SystemsShutdown Systems
• The ACR-1000 design includes two diverse, independent shutdown systems– SDS1 consists of
mechanical shutoff rods
– SDS2 injects a neutron-absorbing poison into the heavy water moderator
• Both shutdown systems execute their function via the low-pressure moderator system
16
Emergency Coolant Injection SystemEmergency Coolant Injection System
• Four sets of ECI accumulators are header dedicated, and shared between HTS loops
• Accumulators contain H2 O, pressurised by compressed N2 gas
• Four core make-up tanks
17
ACR-1000 System OverviewACR-1000 System Overview
18
ACR-1000 1200 Mwe classACR-1000 1200 Mwe class
19
U.S. EPR Design Overview
20
AREVA US EPR DesignAREVA US EPR Design
• The EPR is designed by AREVA • The design is based on established Pressurised
Water Reactor (PWR) technologies utilising the vertical reactor pressure vessel design
• The design builds on proven engineering concepts of the established N4 and KONVOI technologies
• It uses light water as the coolant which also acts as the moderator
• The fuel is of a standard 17x17 design• Off-line fuelling during outages
21
US EPR Key ParametersUS EPR Key Parameters
• Power: 4590 MW thermal, 1600 MW electrical (net)• Number of fuel assemblies: 241• Number of fuel rods per assembly: 265• Regular vertical lattice in a reactor pressure vessel• Moderator: light water• Reactor coolant system: light water• Fuel enrichment: up to 5% by weight• Operating pressure: 15 MPa• Operating temperature: 330 Celsius
22
EPR LayoutEPR Layout
23
A solid foundation of operating experienceA solid foundation of operating experience
24
Reactor Coolant SystemReactor Coolant System
25
26
Reactor Pressure Vessel InternalsReactor Pressure Vessel Internals
27
The Four Train ConceptThe Four Train Concept
Each safety train is independent and located within a physically separate building.
28
US EPR Safety SystemsUS EPR Safety Systems
• Control systems• Reactivity control systems
– Rod cluster control assemblies– Extra borating system
• Emergency core cooling system– accumulators– medium head safety injection system– low head safety injection system
• Emergency feedwater system
29
US EPR Safety SystemsUS EPR Safety Systems
• Containment– double walled concrete with steel liner– containment isolation and annulus
ventilation• Systems that can mitigate against severe
accidents– pressurizer severe accident valves– atmosphere control– core melt spreading compartment with
core melt cooling– robust containment
30
US EPR Safety SystemsUS EPR Safety Systems
• Safety support systems– in-containment refuelling water storage tank– essential cooling water and service water– essential electrical power supplies
31
Rod Cluster Control Assembly (RCCA)Rod Cluster Control Assembly (RCCA)
• Each RCCA has 24 rods• Provides both shutdown
and control functions• Control rod drive
mechanism with magnetically operated jack
32
SIS/RHR SystemsSIS/RHR Systems
33
Shielded ContainmentShielded Containment
34
Severe Accident Mitigation: Views of Corium Spreading Area & IRWST Severe Accident Mitigation: Views of Corium Spreading Area & IRWST
35
Pressurizer Discharge Valves ArrangementPressurizer Discharge Valves Arrangement
36
U.S. EPR Design Overview
37
The Westinghouse AP1000The Westinghouse AP1000
A compact station• 3415 MWt, primary system• 1117 MWe• 2-loops, 2 steam generators
38
Westinghouse AP1000 DesignWestinghouse AP1000 Design
• The AP1000 is designed by Westinghouse Electric Company
• The design has evolved from established PWR technology utilising the vertical reactor pressure vessel design
• The design includes a number of passive safety features
• It uses light water as the coolant which also acts as the moderator
• The fuel is of a standard 17x17 design• Off-line fuelling during outages
39
AP1000 Key ParametersAP1000 Key Parameters
• Power: 3415 MW thermal, 1117 MW electrical (net)
• Number of fuel assemblies: 157• Number of fuel rods per assembly: 264• Regular vertical lattice in a reactor pressure vessel• Moderator: light water• Reactor coolant system: light water• Fuel enrichment: up to 5% by weight• Operating pressure: 15.5 MPa• Operating temperature: 325 Celsius
40
The AP1000 Nuclear Power PlantThe AP1000 Nuclear Power Plant
• Design Certification includes:– Containment– Auxiliary Building– Annex Building– Turbine Building– Radwaste Building– Diesel Generator
Building– Everything in
buildings– Associated yard
structures
• It is based upon:– Passive Design– Passive Core Cooling– Passive Control Room
Habitability– Passive Containment
Cooling– Passive Seismic Fire
Protection– Passive Security
Features
41
Reactor Coolant SystemReactor Coolant System
• Canned motor pumps mounted in steam generator lower vessel head
• Elimination of RCS loop seal
• Large pressurizer• Top-mounted, fixed in-
core detectors• All-welded core
shroud• Ring-forged reactor
vessel
42
Fuel AssemblyFuel Assembly
• Robust fuel design– Advanced ZIRLO material– Debris tolerant features– Intermediate mixing grids– Integral burnable
absorbers– Larger fission gas plenum – Annular enriched axial
blankets– Low cobalt removable top
nozzle
• High fuel reliability
43
AP1000 Safety SystemsAP1000 Safety Systems
• Control systems• Shutdown system
– Reactor trip system• Emergency core cooling passive system
– core make-up tanks– accumulators– low pressure long term cooling system
• Automatic depressurisation system
44
AP1000 Safety SystemsAP1000 Safety Systems
• Containment– free standing steel containment
surrounded by a concrete shield building– containment isolation
• Systems that can mitigate against severe accidents– Passive feature approach
• Safety support systems– reserve water
45
Severe Accident Mitigation Design In-Vessel Retention Severe Accident Mitigation Design In-Vessel Retention
In the unlikely event of core melt• AP1000 designed to retain core
debris within the reactor vessel• No penetrations below nozzles
– Reactor vessel insulation design allows cooling water flow path on outside of vessel
– Cooling flow driven by natural circulation
– Water source: In containment refueling water storage tank
– Automatic Depressurization System relieves pressure build up
• Small release frequency: 5.9 x 10-8
per reactor year; URD requirement: <10-6 per reactor year
46
Passive Core Cooling System
• AP1000 does not rely on safety- grade AC power
• Passive residual heat removal
• Passive safety injection
• Passive containment cooling
• Long term safe shutdown state:72 hours without operator action
47
Passive Containment Cooling SystemPassive Containment Cooling System
48
The Westinghouse AP1000The Westinghouse AP1000
A compact station• 3415 MWt, primary system• 1117 MWe• 2-loops, 2 steam generators
49
Similarities and DifferencesSimilarities and Differences
• All the technologies– incorporate defence-in-depth principles– are based on sound engineering principles– demonstrate a high level of safety
• All the technologies include– design provisions for the control of
anticipated operational occurrences– design provisions for the control and
mitigation of design basis accidents– provisions for the mitigation of very low
frequency severe accidents
50
Similarities and DifferencesSimilarities and Differences
• All the technologies– incorporate passive safety features, some
more than others– have robust containments– have been designed with modular
construction in mind• There are differences with respect to
– overall power– the basic pressure boundary technology– the approaches to mitigate severe accidents– foot-print
51
In ConclusionIn Conclusion
• A high-level overview of the 3 technologies has been provided
• Focused on design aspects that could have bearing on the EIS
• Information has been provided on– principal features of the designs– key operational parameters– normal operation– control and mitigation of potential accidents
• Staff is ready to respond to questions
Cooling Water System Technology
and Associated Environmental
Impacts
Cooling Water System Technology
and Associated Environmental
ImpactsPresentation to the Bruce New Build Panel
May 07, 2009 Ottawa
Malcolm McKee and Don Wismer
Environmental Risk Assessment Specialists:Directorate of Environmental and Radiation
Protection and AssessmentCanadian Nuclear Safety Commission
Presentation to the Bruce New Build PanelMay 07, 2009 Ottawa
Malcolm McKee and Don Wismer
Environmental Risk Assessment Specialists:Directorate of Environmental and Radiation
Protection and AssessmentCanadian Nuclear Safety Commission
Canadian NuclearSafety Commission
Commission canadiennede sûreté nucléaire
nuclearsafety.gc.canuclearsafety.gc.ca1
Cooling Water System Technology & Potential Environmental Impacts Cooling Water System Technology & Potential Environmental Impacts
Purpose of the Condenser Cooling Water System (CCW)Basic Types of Cooling Water Systems
Open Cycle (Once-through)Closed Cycle (Re-circulating)
Wet TowersDry Towers
Environmental Aspects of Cooling Systems
Presentation Outline
2E-DOCS #3370963
Purpose of the Condenser Cooling Water System (CCW)
Purpose of the Condenser Cooling Water System (CCW)
Dissipate excess heat from the steam turbines.Condenses steam to water for recycling back to the steam generator. Cooling water system selection is independent of reactor design.
Cooling Water System
3
Types of Cooling Systems Types of Cooling Systems
Basic Types of Cooling Water SystemsOpen Cycle (Once-through)Closed Cycle (Re-circulating)
Wet TowersDry Towers
4
Types of Cooling SystemsTypes of Cooling Systems
Once-throughContinuous withdrawal from a waterbody through the condenser with release back to the waterbody.
5
Types of Cooling SystemsTypes of Cooling Systems
Once-through Water RequirementsRequires large volumes of waterCanadian Great Lakes reactors
Intake 150 to 200 m3 per second Discharge equivalent volume of heated CCW to environment
6
Types of Cooling SystemsTypes of Cooling Systems
Closed Cycle or Re-circulating CCW re-circulatedHeat removed from CCW by an additional cooling device
7
Types of Cooling SystemsTypes of Cooling Systems
Closed System Water Requirements
Use 90 to 99% less water than once- throughAfter initial filling withdrawals are restricted to “make-up” water to replace
Evaporative lossesBlowdown losses
Small discharges restricted to periodic blowdown
8
Large artificial cooling pondsAdditional spray cooling
Cooling TowersWet coolingDry Cooling Natural DraftMechanical Draft
Types of Cooling Systems
Closed Cycle Cooling Devices
9
Types of Cooling Systems
CCW exposed directly to the atmosphereHeat dissipation through evaporative lossesTower design enhances contact between CCW and atmosphere
WET Cooling Towers
o Fill
o Natural Splash Fill
o Film Fill
o Natural Draft
o Mechanical Drafto Induced Draft
o Forced Draft
10
Types of Cooling Systems
Natural Draft Cooling Towers
11
Types of Cooling Systems
Mechanical Draft Cooling Towers
12
Types of Cooling Systems
Mechanical Draft Cooling Towers
13
CCW or steam directly pumped through network of finned tube elements, coils or conduits.Heat loss due to conduction and convection to air forced across the cooling elements
No direct exposure to atmosphereNatural draft or mechanical draft towers can be used.
Types of Cooling Systems
Dry Cooling Towers
14
Dry Cooling TowersLowest water requirements of all systemsNo evaporative losses
Types of Cooling Systems
15
Hybrid Cooling SystemsCombination of two or more technologies
Types of Cooling Systems
16
Hybrid Cooling Systems
Types of Cooling Systems
Wet with Part DryPlume abatementDry section above wet zone mitigates water vapour releasesPrevents fogging and icing
Dry with Part WetImproves performance in hot weatherWater sprays used to evaporatively cool finned tubes during periods of extreme temperature
Hybrid Cooling Towers
17
Hybrid Cooling Systems
Types of Cooling Systems
Wet-Dry for Plume Mitigation
18
Types of Cooling Systems
One of the initial wet-dry towers built in 1980s for German reactor
Hybrid tower proposed for the new reactor unit(s) at Calvert Cliffs facility in Maryland, USA.
Nuclear sites using or proposing wet-dry towers.
19
Environmental Impacts Cooling systems
Condenser cooling water systems are the primary source of actual and potential environmental impacts related to the routine operation of nuclear power plants.
Both US NRC generic EIAs and the CNSC required site specific operational ERAs for existing Canadian reactors indicate that:
20
Environmental Impacts Cooling Systems
Impingement and entrainment of aquatic biota (e.g., fish, invertebrates)Discharge of heated waterRelease of chemicals
Biocides, chemicals associated with managing corrosion and scaling problems
Physical disruption with construction of intake structures, canals etc.Changes in local lake currents and bed scour
Once-through Cooling SystemsThe major environmental issues are:
21
ImpingementKilling of aquatic biota due to entrapment against intake screens
EntrainmentIntake of aquatic biota through the CCW system.
A fraction are killed or injured as a result of physical abrasion, or exposure to heat, biocides or other chemicals.
Environmental Impacts Cooling Systems
Once-through Cooling SystemsImpingement/entrainment remains the largest environmental impact for NPP in Canada.
22
Environmental Impacts Cooling Systems
Once-through Cooling Systems
Surface shore side intake: Approx. 20 tons per year
Offshore velocity cap:Approximately 8 to 20 tons per year
Offshore deep water pre-cast porous bottom intake:300 to 600 kg per year
Impingement Mortality:
23
Mitigated through combination of intake design and siting
Environmental Impacts Cooling Systems
Once-through Cooling Systems
Large numbers of:fish larvaefish eggsaquatic macroinvertebrates
Entrainment:
24
Estimated survival of 25 to 90% for fish (species dependant). Macroinvertebrate survival rates uncertain but reported to be high.
Mitigation is challenging
Environmental Impacts Cooling Systems
Impingement/entrainment impacts have recently received great deal of attention from the US EPA.
EPA launched a series of investigative studies
Impingement/entrainment effectsAssessment of Best Technology Available including economic feasibility
Phase I Rule: New Builds (2001)Equivalent of Closed System (re-circulating)
Phase II Rule Existing Facilities (2004 under court challenge)Mitigation required for existing once-through systems
25
Environmental Impacts Cooling Systems
Once-through Cooling SystemsThermal releases: CCW released back to the waterbody at a higher temperature
Direct Thermal Shock MortalityEgg mortality from thermal plumeThermal shock from rapid reactor shut downs
Indirect Thermal Discharge EffectsAlteration of habitat and aquatic community compositionAlteration of development rates of fish and/or their prey speciesDisruption of normal shoreline fish movement patterns
26
Mitigated with proper modern diffuser design and siting
Environmental Impacts Cooling Systems
Once-through Cooling Systems
Chemical releases Biocides, water conditioning chemicals
Changes in local lake currents and bed scourLocalized physical aquatic habitat disruption
27
Continued ….
Mitigated with best available technology and environmental management practices.
Environmental Impacts Cooling Systems
Darlington:Canada’s most advanced once-through design
28
Environmental Impacts Cooling Systems
Darlington:Discharge Diffuser
Intake Structure
29
Environmental Impacts Cooling Systems: Summary
Adverse effect Once-through
Energy penalty Low
Impingement Low-High
Entrainment High
Thermal (Aq) Low - High
Chemical release (Aq)
Low
Plumes/Drift ---
Noise ---
Land Use / Habitat
Aquatic:M-HTerrest: L
30
Environmental Impacts Cooling Systems
Wet Cooling Towers
Potential Environmental Issues
Chemical releases: Blowdown and biocidesWater condensate plume and drift
Drift depositionFogging and IcingHuman Health
NoiseLand area
31
Environmental Impacts Cooling Systems
Wet Cooling TowersDrift and Condensation Plumes
32
Environmental Impacts Cooling Systems
Environmental Impacts Cooling Systems
NoiseLand Area
Wet Cooling Towers
33
Environmental Impacts Cooling Systems: Summary
Adverse effect Once-through Wet Tower
Energy penalty Low Mod. - High
Impingement Low-High Low
Entrainment High Low
Thermal (Aq) Low - High ---
Chemical release (Aq)
Low Low - Mod.
Plumes/Drift --- Mod. - High
Noise --- Mod.
Land Use / Habitat
Aquatic:M-HTerrest: L
Aquatic: LTerrest:L-M
34
Environmental Impacts Cooling Systems
Dry Cooling Towers
Remaining Potential Environmental Issues
Small amounts of blowdown (No evap. losses)NoiseLand area
35
Environmental Impacts Cooling Systems: Summary
Adverse effect Once- through
Wet Tower
Dry Tower
Energy penalty Low Mod. - High High
Impingement Low-High Low ---
Entrainment High Low ---
Thermal (Aq) Low - High --- ---
Chemical release (Aq)
Low Low - Mod. Low
Plumes/Drift --- Mod. - High ---
Noise --- Mod. Mod. - High
Land Use / Habitat
Aquatic:M-HTerrest: L
Aquatic: LTerrest:L-M
Aquatic: LTerrest:M-H
36
Environmental Impacts Cooling Systems: Summary
Adverse effect Once- through
Wet Tower
Dry Tower Hybrid Tower
Energy penalty Low Mod. - High High Mod. - High
Impingement Low-High Low --- Low
Entrainment High Low --- Low
Thermal (Aq) Low - High --- --- ---
Chemical release (Aq)
Low Low - Mod. Low Low - Mod.
Plumes/Drift --- Mod. - High --- Low
Noise --- Mod. Mod. - High Mod.
Land Use / Habitat
Aquatic:M-HTerrest: L
Aquatic: LTerrest:L-M
Aquatic: LTerrest:M-H
Aquatic: LTerrest:M-H
37
nuclearsafety.gc.canuclearsafety.gc.ca
Radioactive Waste Management for New Builds
Radioactive Waste Management for New Builds
Don HowardDirector, Wastes and Decommissioning Division
Don HowardDirector, Wastes and Decommissioning Division
Canadian NuclearSafety Commission
Commission canadiennede sûreté nucléaire
nuclearsafety.gc.canuclearsafety.gc.ca
OutlineOutline
1. Waste Management Strategy
2. Low- and Intermediate-Level Waste
3. Used Nuclear Fuel
4. Short- and Long-Term Management
1. Waste Management Strategy1. Waste Management Strategy
• Waste Management Strategy- transferred to a licensed facility- management in a dedicated facility
• Waste Management Plan- characterization- minimization- segregation
2. Low- and Intermediate-Level Waste2. Low- and Intermediate-Level Waste
• Types of radioactive
- solid/liquid/gaseous
• Quantity of wastes produced
• Enabling facilities required
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2. Example of Intermediate-Level Waste Storage
1. Example of Low-Level Waste Storage
3. Used Nuclear Fuel3. Used Nuclear Fuel
• Types of used nuclear fuel- CANDU- Areva/Westinghouse
• Quantities
• Wet Storage
1. Example of used nuclear fuel wet storage poolsImage courtesy of OPG
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Examples of Interim Dry Storage of Used Nuclear Fuel Examples of Interim Dry Storage of Used Nuclear Fuel
3. Dry cask storage area
4. Dry cask storage system with vertical cylinders. 2. Inside of DSC
1. Dry Storage Containers (DSC)
4. Short- and Long-term Management4. Short- and Long-term Management
• Management strategy for the life of the facility
• Management strategy beyond life of the facility
