Preparedness at PFBR Kalpakkam to meet

the challenges due to Natural events

Prabhat Kumar, Project Director, PFBR,

Director construction BHAVINI

BHARATIYA NABHIKIYA VIDYUT NIGAM LIMITED

(A Government of India Enterprise)

PFBR REACTOR ASSEMBLY Item

1 Main Vessel

2 Core Support Structure

3 Core Catcher

4 Grid Plate

5 Core

6 Inner vessel

7 Roof slab

8 Large Rotatable Plug

9 Small Rotatable Plug

10 Control Plug

11 Absorber Rod Drive Mechanism

12 Transfer Arm

13 Intermediate Heat Exchanger

14 Primary Sodium Pump

15 Safety Vessel

16 Reactor Vault

PFBR Details

• No. of fuel Assemblies

• No. of pins in one Sub Assembly

•Refueling interval

• Pu enrichment Zone I/II

• Rx Coolant inlet /outlet

• Steam Temp. / Pressure

: 181

: :217

: 185 EFPD

: 20.7 / 27.7 wt %

: 397 / 547 ºC

: 490 ºC / 167 Kg/Cm2

PFBR Flow Sheet

PFBR

• PFBR is being constructed near the coast of Bay

of Bengal.

Task Force has been constituted to review the issues

related to the:

• safety of reactor,

• spent fuel storage facility

• Multiunit site

• and other related issues arising due to natural

events.

Issues • Public perception is very low

– Equipment failure

– Human error

– Matural Event

Public is affected

• Livelyhood

• Fear of new issue:

– Design?

– QA?

– Materials?

– Manufacturing?

– Terrorism?

– Insider Threat?-Even operator must not be able to damage the core

Public is not concerned of source of

electricity-

Several decades of effort of nuclear

technology development is

at risk if we can not win public

confidence

Site

• Coastel- What if flooded due to cyclone

• Height of water during tsunami

• Effect of splash due to tsunami;

– Equipment

– Drainage

To be taken care

•Reactor Shutdown, maintaining core cooling and

containment integrity

• Gravity drop

•Cooling in every scenario:

• Operational Grade Decay Heat Removal

(OGDHR) • 4 loops are provided, each loop having capacity of 8

MWTh. (Total decay heat 20 MWTh)

Safety assessment of external events leading to BDBA

conditions to review and address the following parameters /

issues :

• Capability for reactor shut down, maintaining shut

down condition and core cooling

• Capability to maintain containment integrity under

credible BDBA conditions

Review of DBA and BDBA conditions to assess

the strengthening / upgradation of the systems

required to ensure the containment integrity.

Provision of reactor trip on seismic event

• Guard pipe is provided around primary sodium

piping

• Leak collection trays are provided for the

secondary sodium piping.

• All pipe lines are of welded construction-

No valves in primary main circuit

• Sodium fire fighting system is established

Support Systems • Alernate Battery bank

• Spares

• Obstruction clearence

• Communication

• Large scale public movement

• Shelters

Storage of large quantity of Sodium in the

Primary and Secondary systems

• Whether SGB could get flooded

– Can Sea water enter and affect the SS

– Whether fire fighting system is adequate

– Whether Cables have joints that can get affected

– Whether Adequate diesel supply can be ensured

– Water sources

– Can servive water, raw water and DM water get

affected due to sea water ingress?

Spent fuel Storage

Review of the spent fuel storage pool for seismic event

higher than the design value.

Review of possible cracks due to higher seismic, possible

pipe line failure and provisions to make up the water level.

Review of any possible fall of heavy object on storage pool

during the seismic event.

Spent fuel Storage

• Spent fuel is kept in the spent fuel storage location in

the reactor core for about two cycles.

• Hence decay heat of the spent fuel will be less

when it is removed for storage in spent fuel

storage pool.

• 45,000 Litres capacity demineralised water storage

tank installed in the Fuel Building can supply water

to spent fuel storage bay in case of failure of normal

source.

• Yet provision planned for additional cooning

facility

Effect on Spent Fuel and Fresh Fuel

assemblies storage facilities to remain

intact

• Analysis

• Water supply possibility

•Availability of Diesel Generator beyond design

basis scenario

•Possibility of hooking up back-up power supply

system in the event of plant Diesel Generator

unavailable

Availability of Emergency Diesel Generators

on wheel/ provision of backup power supply-

Levels and Roads

Accident management strategy

• Emergency preparedness – Emergency Crew

• Adequacy of the approaches to the plant site to

handle emergency scenarios

• Accident management

• (site & off site-NDMA, NDRF)

Preliminary review has indicated that we

donot have much concern- many concerns

were addressed after 2004 tsunami

• PFBR plant is designed to be safe in all

natural eventualities such as tsunami ,

earthquake, cyclone & flood.

• Kalpakkam comes in Seismic Category

Zone III as per the seismic classification.

• For PFBR, the Design Basis Flood Level is fixed

as 6.45 metres above Mean Sea Level (MSL)

based on 1000 years return period

• During the worst ever Tsunami that stuck

Kalpakkam in Dec. 2004, the maximum water

level rise was 4.71 metres above MSL.

• After the Tsunami at Kalpakkam in Dec. 2004,

shore protection and Tsunami bund made out of

engineered boulders stacked at a height of 5.4

Meters above MSL was erected for breaking

the intensity of sea waves during tsunami.

25

Tsunami bund

Shore protection

• The finished floor level of Safety related

Buildings are at 9.604 metres above Mean Sea

Level (MSL) :

• The finished floor levels of Safety related

Buildings are 3.15 metres above Design Basis

Flood Level (6.45M)and 4.9 metres above the

maximum water level rise observed during

Tsunami in Dec. 2004 (4.71 M))

• Hence operation of Emergency Diesel

Generators, reactor safe shut down & cooling

and spent fuel cooling will not be affected

during a design basis Tsunami event.

Hydrogen Issue

•In PFBR water is not used as the coolant for reactor.

This precludes any possibility of hydrogen

generation/explosion in RCB.

•Fuel clad material is not Zirconium (it is Alloy D-9 an

alloy of Cr , Ni, Mo, Ti & Si). Hence no metal – water

reaction & hydrogen generation in Spent fuel storage

facility in case loss of cooling.

•However Hydrogen due to BSC water and sodium

need to be studied

Emergency Diesel Power

•PFBR is provided with four diesel generators

•Two are sufficient to meet the station requirement

• All four DGs are in separate buildings

2 are in east . Remaining 2 are in the west side of Main

plant building , away from sea side.

• Located at 9.604 meters above MSL

• An in-depth study by the Task Force is in

progress to review & identify any weakness

Based on the review and recommendations of

Task Force, modifications will be carried out to

address these issues.

Erection of steam generator

• Mock up work completed as per the guide lines

of PDSC.

• Welding commenced

Sea water Intake

1. Sinking of caisson has reached

beyond soft rock region.

2. Concreting of caisson completed

for 12 m depth from cutting edge.

3. Inside caisson chiseling and

grabbing work is in progress.

4. On top of jetty pipe line pedestal

work is in progress.

Major TG equipment's at site

Around 4000 Tons of material

reached site in TG package

Thank you