Relazione Finale Presentation - Daniel Sirbu

8/3/2019 Relazione Finale Presentation - Daniel Sirbu

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Universit degli Studi di GenovaFacolt di Ingegneria

Master di II LivelloSviluppo e Gestione del Mercato

Energetico ElettricoRelazione Finale

Preparato da: Daniel Srbu


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1. Introduction ofAnsaldo Nucleare (ANN)

Ansaldo Nucleare has been created in 1989 as anindependent branch in the FINMECCANICA Group

In December 1999 Ansaldo Nucleare was incorporatedby Ansaldo Energia S.p.A, a company belonging 100%

to the FINMECCANICA Group, as a Division. Starting from November 2005 Ansaldo Nucleare became

a separate Company, even if fully controlled by AnsaldoEnergia.

The Company can rely on a stable work force of about175 experts, plus 25 sub-contracted specialists mainlyinvolved in site activities.


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2. Products & Solutions

Engineering and Construction Services

Development of New Generation Nuclear Reactors

Plant Operation Assistance Waste Management

Decommissioning


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2.1 New Nuclear Power Plants

EPP - European Passive Plant

AP1000 US - Licensing and Extended

Licensing Support

ADS - Accelerator Driven System


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2.2 Nuclear Service

ENGINEERING AND CONSTRUCTION SERVICES Completion of Cernavoda Unit 2 - Romania Integrated Automated Monitoring System for Chernobyl

Ukraine

Leak Before Break (LBB) Analysis for VVERs MEDZAMOR NPP (Armenia) Application of LBB (Leak

Before Break) Methodology to the Primary System andSurge Lines

MEDZAMOR NPP (Armenia) - Definition of the New LDS

(Leak Detection System) Configuration CIRCE Experimental Facility MEGAPIE Experimental Facility


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2.2 Nuclear Service

PLANT OPERATION ASSISTANCE

Control System for Fuel Handling Machines - China

Service on Cernavoda Unit 1 - Romania

Technical Assistance to Safe Shutdown of SuperphnixFBR-France

Plant Life Assessment for Embalse CANDU NPP -Argentina


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2.3 Waste & Decommissioning

WASTE MANAGEMENT CORA-Saluggia (Italy): High Level Liquid Waste (HLW) Treatment

Plant COVRA (The Netherlands): Bunker and Transfer Cranes JRC-ISPRA: Liquid Waste (LLW) Storage - STEL

KHMELNITSKY NPP (Ukraine) - Treatment of Backlog ofRadioactive Waste Water Chernobyl (NPP, Ukraine): Low LevelLiquid Waste Treatment LRTP

New storage facility for high radioactive level liquid waste atSaluggia site (Italy)

New Solid Waste Retrieval Facilities at the Ignalina NPP (Lithuania)

Safety evaluation of Italian nuclear sites for SOGIN

DECOMMISSIONING GARIGLIANO & CAORSO NPP (SOGIN; Italy)


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3. Technical Departments

System Engineering (ISN)

Plant Engineering (IMN)

Nuclear Technologies Excellence Center (ETN),

that is also articulated according to the followingTechnical Areas:

Nuclear Safety and Calculations (SCN)

Thermohydraulics and Simulation (TSN)

Special Components and Structural Analyses(CSA)


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3.1 Nuclear TechnologiesExcellence Center (ETN)

Thermohydraulics & Simulation (TSN) preparation of phenomenologic plant or system/component simulation models; analysis of the fluodynamic loads on structures, piping and components, as a support to the IMN

Department; pre-testing and post-testing analyses for experimental plants and specialistic support to the SCN

Technical Area for defining the experimental thermohydraulic tests and the results engineeringinterpretation;

implementation, operating performance and maintenance of the pertaining thermohydrauliccalculation programs;

development and implementation of calculation skills in the Computational Fluid Dynamics field; support to the CSA Technical Area for the thermohydraulic analysis/design and the definition of

forced elements for calculation of components fluoinduced vibration; set-up of plant control algorythms through simulation techniques in compliance with the operating

specifications worked out by ISN; detailed design of supervision systems and operators aid systems according to the system

specifications worked out by ISN;

issue of the technical documentation for purchase order, proposals technical evaluation, follow upof the supplies concerning subsystems and components related to simulators, supervisionsystems and operators aid systems;

maintenance of the Companys applications know-how both for technical and managementpurpose, with particular care for the technical/scientific calculation codes;

coordination of procurement, management and development of new programs, in closecooperation with users, caring for their correct implementation within the computer programscatalogue assigned to ANSALDO Nucleare, and the users training;


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3.2 System Engineering (ISN)

definition of the functional and safety performance to be assured for the plant design,also considering the Customers requirements, including the preparation of thefunctional specifications (Design Guides) for the different plant systems;

conceptual and detailed design of the fluid systems, up to the definition of thefunctional requirements for each component;

conceptual and detailed design of the electrical systems, up to the definition of thefunctional requirements for each component;

definition of the general plant automation architecture, indication of the generalcriteria for the protection and control systems and preparation of the relatedspecifications on the basis of the functional requirements coming from the plantintegrated analyses performed;

analysis of the man-machine interface problems, functional design of the controlroom, conceptual design of the supervision and operators aid systems;

performance of integrated design reviews;

preparation of the documentation requested for the plant licensing; issue of the purchase order technical documentation, proposals technical evaluation,follow up of the supplies related to the electrical, instrumentation and control systemsand functional package systems;

preparation of start-up specifications and operating manuals for the pertainingsystems, as well as at the integrated plant level.


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Case Study

AP1000 passive residual heat removal (PRHR) -In-containment Refueling Water Storage

Tank (IRWST)

The project was performed in Thermohydraulics &Simulation (TSN) department.


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SCOPE OF WORK

Scope of this work is to investigate thetemperature, pressure and void fraction of

the In-containment Refueling Water StorageTank (IRWST) during passive residual heatremoval (PRHR) operation. The simulations

are carried out using Relap5/mod 3.


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SYSTEM DESCRIPTION

The AP1000 is an advanced nuclear power plant that uses passive safety featuresto enhance plant safety and to provide significant improvements in plantsimplification, reliability, investment protection and plant costs.

The PRHR HX tube bundle is a C-tubeheat exchanger immersed in the In-containment Refueling Water Storage Tank (IRWST) located above the reactorcore, promoting natural circulation heat removal between the reactor core and theIn-containment Refueling Water Storage Tank.

The primary flow during decay heat is established with the hot inlet flow entering atthe top and exiting at the bottom of the tube bundle. The secondary fluid is the waterin the In-containment Refueling Water Storage Tank (IRWST) which is kept atatmospheric conditions. The water in the vicinity of the tube bundle is expected toheat up and establish natural circulation. Secondary boiling can occur due to thecombination of high primary inlet temperature with the tube wall temperature greaterthan the saturation condition.

The tube bundle has a C-tube configuration, oriented with horizontal sections

attached to each tube sheet and a vertical section between the horizontal sections. The In-containment Refueling Water Storage Tank (IRWST) is modeled as a

region surrounding the PRHR HX and is considered to be at atmospheric pressure(14.7 psia, 1.014x105 Pa) and at 80 F. The tank is assumed to be open on the top.

Flow in the In-containment Refueling Water Storage Tank (IRWST) is verticallyupward through the tube bundle. Horizontal cross flow is considered within the tubebundle.


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RELAP5 MODEL DESCRIPTION

The Relap5/mod3.3 is able to predict the two phase flow behavior in In-containmentRefueling Water Storage Tank and to compute the natural circulation flow based onthe balance of gravity driven circulation. The code is used to predict the IRWSTtemperature and void fraction distributions.

The In-containment Refueling Water Storage Tank (IRWST) is modeled as a tankdivided in a certain number of equal volumes with a mesh x = y = z = 14.2567 in= 1.188 ft, i.e. a rectangular tank with the above dimensions 14 x 7 x 21 (Fig.5.4).The tank is considered to be open at the top and connected to the atmosphere.

The tube bundle in the Relap5 model has to approximate the passive residual heatremoval heat exchanger (PRHR HX) that provides decay heat removal (Fig. 5.3). Itis positioned between IZ=3 and IZ=5 at the bottom and IZ=17 and IZ=19 at the topand IY = 3 to 5 at the top and bottom for horizontal positioning. The vertical bundle ispositioned between IX = 7 to 12 and IY = 3 to 5.

The PRHR HX tube bundle represents 689 tubes. The resulting total heat transfersurface area for this calculation is 4675 ft2 = 434.3 m2.

The IRWST portion is simulated by a number of vertical pipes connected by cross

flow junctions as shown in Fig.5.3. At the top level of each vertical pipe a timedependent volume is connected to simulate the open atmosphere. The last volume ofthe IRWST vertical pipes is partially filled with water, i.e. the IRWST level is located inthe last vertical volumes.

This is a key feature of the simulation, in fact such simulation characteristicseliminates completely the usual numerical circulation inside the pool.


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Relap5 main components anddescription

PRHR Tube Bundle:

component 110 (time dependentvolume), component 555 (singlejunction), component 550, 551, 552,553 (branch) simulating the hot inletflow;

component 119 (time dependentvolume), component 565 (timedependent junction), component 560,561, 562, 563 (branch) simulating the

outlet flow; components (pipe):

112 122 182, 172 192 132,162 152 142

114 124 184, 113 123 183,174 194 134

173 193 133, 164 154 144,163 153 143

167

157

147, 177

197

137,117 127 187

simulating the tube bundle;

heat structures (component 1112 to1167) from thermal connection of theprimary to secondary side (not in figure).

Fig.5.3 AP1000 tube bundle nodding


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Relap5 main components anddescription

IRWST POOL: components 201 to 298 (time

dependent volume) and component299 (multiple junction) simulatingthe open atmosphere; (not shown infigure, volume 201 connected to top ofpipe 1 etc. using multiple junction299);

component 001 to 098 (pipe)simulating the IRWST (vertical pipesvolumes from 1 to 98);

components (pipe): 112 122 182, 172 192

132, 162 152 142 114 124 184, 113 123

183, 174 194 134 173 193 133, 164 154

144, 163 153 143 167 157 147, 177 197

137, 117

127

187 simulating the tube bundle (location

shown by yellow projection); cross flow junction 401 to 533

connection between vertical pipesvolumes in the X direction;

cross flow junction 601 to 736connection between vertical pipesvolumes in the Y direction.

Fig.5.4 - The In-containment RefuelingWater Storage Tank nodding

(IRWST)


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BOUNDARY AND TRANSIENT CONDITIONS

State point 1:

Parameter Value (US Units) Value (SI Units)

Heat Load 175.36x106 Btu/hr 52.97 MWt

Primary Flow 133.7 lbm/sec 60.65 kg/sec

Primary Inlet Temperature 520 F 544.3 K

IRWST Inlet Temperature 80 F 299.8 K

IRWST Pressure 2000 psia 13.79x106 Pa

State point 2:


Heat Load 112.47x106 Btu/hr 32.933 MWt

Primary Flow 111.3 lbm/sec 50.48 kg/sec

Primary Inlet Temperature 420 F 488.7 K


IRWST Pressure 2000 psia 13.79x106 Pa

State point 3:


Heat Load 95.625x106-102.455x106

Btu/hr30 MWt

Primary Flow 132.277 lbm/sec 60 kg/sec

Primary Inlet Temperature 445.734 F 503 K


IRWST Pressure 1256.483 psia 12.80x106 Pa


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CALCULATION RESULTS

In the following it can be observed the temperature distribution and void fraction forthe tests performed. For each state point there are three pictures that represent thetemperatures (one for each vertical plane of the tube bundle) and three pictures thatrepresent void fractions for the PRHR tube bundle (one for each vertical plane ofthe tube bundle).

The primary temperature distribution plots clearly show the primary temperaturedecreases rapidly in the upper horizontal hot leg and the upper vertical leg of the tube

bundle, indicating that most of the heat transfer occurs in these regions. The power extracted for each state point is: 52 MWt for state point 1, 30.98 MWt forstate point 2, 31.97 MWt for state point 3. The primary exit temperature for eachstate point is: 350 K (170.334 F) for state point 1, 345.28 K (161.839 F) for state point2, 380.33 K (224.923 F) for state point 3.

The main purpose of the activity was to verify the expected heat exchange of thePRHR tube bundle.

As shown by the table values which reports the expected heat exchange the

calculated value is very close to the expected power removed by the system. Also for the last calculated condition (saturated IRWST pool) the system is still able

to remove power from the primary side.


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Primary temperature distribution for line 112-114-117

100.000

150.000

200.000

250.000

300.000

350.000

400.000

450.000

500.000

550.000

0,5

4

1,0

8

1,6

2

2,1

6

2,7

0

3,2

4

3,7

8

4,3

2

4,8

6

5,4

0

5,9

4

6,4

8

7,0

2

7,5

6

8,1

0

8,6

4

9,1

8

9,7

2

10,2

6

10,8

0

11,3

4

11,8

8

12,4

2

12,9

6

13,5

0

14,0

4

14,5

8

15,1

2

15,6

6

16,2

0

16,7

4

17,2

8

17,8

2

18,3

6

18,9

0

19,4

4

19,9

8

20,5

2

21,0

6

1 2 3 4 5 6 7 8 9 1 0 1 1 12 1 3 1 4 15 1 6 1 7 18 1 9 2 0 21 2 2 2 3 24 2 5 2 6 27 2 8 2 9 3 0 31 32 3 3 3 4 35 3 6 3 7 3 8 39

Distance from Primary Inlet (in)

Temperature

(F)

Case-1

Case-2

Case-3

Primary temperature distribution for line 152-154-157

100.000

150.000

200.000

250.000

300.000

350.000

400.000

450.000

500.000

550.000

0,5

4

1,0

8

1,6

2

2,1

6

2,7

0

3,2

4

3,7

8

4,3

2

4,8

6

5,4

0

5,9

4

6,4

8

7,0

2

7,5

6

8,1

0

8,6

4

9,1

8

9,7

2

10,2

6

10,8

0

11,3

4

11,8

8

12,4

2

12,9

6

13,5

0

14,0

4

14,5

8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Distance from Primary Inlet (in)

Temperatu

re(F)

Case-1

Case-2

Case-3


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State point 1 temperatures

Temperaturesfor line 29 - 42




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State point 1 void fraction

Void fractionfor line 29 42

Maximum void fraction is0.236 (c035-19)






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CONCLUSIONS

Scope of this work has been to investigate the temperature,pressure and void fraction of the In-containment RefuelingWater Storage Tank (IRWST) during passive residual heatremoval (PRHR) operation. The simulations were carried out usingRelap5/mod3.

The verification of the calculation shows that the code is able to

correctly predict the outlet passive residual heat removal(PRHR)temperature.

The final results shows that the calculated value is very close to theexpected power removed by the system for all three test casessimulated.

In particular, also for the last calculated condition (saturated IRWST

pool) the system is still able to remove power from the primaryside.

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Relazione Finale Presentation - Daniel Sirbu