fukushima daini independent review and walkdown documents/action 01... · fukushima daini...

Authors:

John Richards, EPRI

Jim Johnson, JJJ & Assoc.

Ken Huffman, EPRI

Greg Hardy, SGH

Antonio Godoy, JJJ & Assoc.

Fukushima Daini Independent Review and Walkdown

IAEA Experts Meeting on Protection

Against ExtremeEarthquakes and

Tsunamis-------------

September 2012

2© 2012 Electric Power Research Institute, Inc. All rights reserved.

Scope of Independent Review and WalkdownFukushima Daini

Reactor BuildingsTurbine BuildingsHeat Exchanger Buildings

Area Description

Seismic Assessment of the earthquake event and effects upon the plants.

Tsunami Assessment of the tsunami effects upon the plants.

Safe Shutdown Technical considerations related to sustaining safe shutdown.

Reporting Reporting of walkdown and review of technical resul ts (EPRI report 1023422).


Response of Fukushima Daini Units to the Earthquake

Event Main Item Main Operation Unit No. 1 Time

Status Prior to

Earthquake

Status of Plants Reactor

Rated Power Operation

-----

Offsite Power Supply3 of 4 Circuits

Available-----

Emergency Diesel Generator

Standby State-----

Emergency Core Cooling System

Standby State-----

Earthquake Occurrence Mar. 11 14:46

ReactorShutdown

Reactor Shutdown

Reactor Auto Scram Yes 14:48

Confirm Subcritical Yes 15:00

Power Supply External Power Supply

2 Circuits Available

-----

Emergency Diesel Generator

Standby State -----

Reactor Pressure, Reactor Cooling

Emergency Core Cooling System

Standby State -----

Close Main Steam Isolation Valve

(Auxiliary Boiler Trip)Yes 15:36

Suppression Chamber Cooling (Start-up of

Residual Heat Removal)Yes 15:30

• Seismic trip

• Normal shutdown

• JMA tsunami warning

• Tsunami counter-measures initiated

All units responded the same,Unit 1 response shown here.


Tsunami Inundation Reenactment CalculationVideo Record of Tsunami

TEPCO calculation resultsreproducing inundation

observations. Direction of View


Unit 1 Emergency Diesel Generator

ExteriorLouvered

IntakeOpening

InteriorAir

FilterFrames

DieselUndergoingMaintenance


Heat Exchanger Buildings

Unit 3 North Building North Equipment Hatch

Unit 4 South Building South Equipment Hatch

Components in HeatExchanger Building

Power Cubicles in Heat Exchanger Building


Post-Tsunami Station Capabilities

Availability of Several Key Functions After the Tsunami, Before Recovery Actions

FunctionsUnit

1Unit

2Unit

3Unit

4

Offsite Power Yes Yes Yes Yes

Emergency Diesel GeneratorsDivision ADivision BHigh Pressure Cooling System H

NoNoNo

NoNoNo

NoYesYes

NoNoYes

Power to Heat Exchanger Building Equipment

No No Partial No

Operable Equipment in Heat Exchanger Building

No No Partial No

Core Cooling (RHR) No No Yes No

Entry Into UnlightedHeat Exchanger Building

Roadway to Site Protected Area

General Conditions


Recovery EffortsRHR Pump Motors

RHR Closed Cooling Pump / Motor

Flooded Motor in Heat Exchanger Building

• First Day• Located replacement motors• Evaluated flooded motors

• Second Day• Motors delivered by

helicopter / overland truck

• Third Day• Installed motors


Recovery EffortsTemporary Power for Heat Exchanger Buildings

• First Day• Located replacement

motors• Evaluated flooded

motors• Located temporary cable• Obtained emergency

power vehicles

• Second Day• Motors delivered by

helicopter / overland truck

• Cable delivered by helicopter

• Third Day• Installed motors• Ran cables


Recovery EffortsTemporary Cable Installation

Temporary Cables from RadWaste Building to HX Build ings

Temporary Cable Connection to Motor

Temporary Cables Inside Heat Exchanger Building


Seismic ObservationsEarthquake Motion EvaluationRecorded Motions Compared to Back-Check (Ss)

Base Mat PGA (Peak Ground Acceleration) Comparisons

East/West (g) North/South (g) Up/Down (g)

Recorded Ss Recorded Ss Recorded Ss

Unit 1 0.234 0.442 0.259 0.442 0.311 0.522

Unit 2 0.200 0.437 0.248 0.436 0.236 0.514

Unit 3 0.220 0.438 0.282 0.436 0.212 0.514

Unit 4 0.209 0.423 0.214 0.423 0.293 0.514


Seismic ObservationsWalkdown Conclusions

• Four person seismic team inspected a cross-section of 27 types of SSCs

• Safety-related SSCs did not appear to have evidence of seismic damage

• Safety-related buildings, foundations and equipment generally in excellent condition, virtually no signs of significant damage

Hair Line CrackIn Concrete


Seismic ObservationsWalkdown Conclusions

• Non-safety related SSCs performed well, very few instances of seismic damage

• Cause of non-safety related gantry crane displacement was not determined

• Inspection results corresponded to the lowest seismic damage intensity level using either the EPRI or IAEA post-earthquake guidelines

Non-Safety Water Tank“Elephant foot” Buckling

Gantry Crane with One Wheel Displaced from Rail

Displaced WheelOne of a Few Damaged

Tank Anchorages


• Complete the evaluation of all (in-structure in addition to base mat) motion records from the earthquake

• Validate truncated motion records by comparison to non-truncated records

• Assign either No Action Required or Action Level 1* to the event using the IAEA post-earthquake guide action levels

• Provide additional focus on any components that had not completed the “back check” process prior to the earthquake and consider Action Level 5* for these* Actions associated with Action Level 1 include focused inspections

and tests (to verify function, operability) and if successful restart the plant

* Action Level 5 actions are the same as Action Level 1 plus re-evaluation of the seismic hazard, if deemed necessary

Seismic ObservationsRecommendations


Tsunami ObservationsDirect and Indirect Flooding

Unit #3 Turbine Building B2 Floor

Pipe Penetration in Unit #1 Reactor Building

Unit #1 Heat Exchanger Building

Ventilation Louver on the Ground Floor of Unit #1 Reactor Building

Direct Flooding Indirect Flooding


Tsunami ObservationsTsunami Recommendations

• Protection of buildings from major water entry points– Significant flooding would not

be expected

– Extent of in-leakage would be manageable

• Component repair / refurbishment / replacement recommendations– >20 component types

– Test methods and acceptance criteria

– Actions for reuse

– Need for on-going periodic testing


Safe Shut Down ObservationsAdequate Cooling, Additional Protection

• Current cooling capabilities were adequate to meet decay heat load needs– Temperature margins sufficient to

address contingencies like replacement of RHRC / RHRS motors

• Recommended additional protection of critical, non-redundant RHR capabilities– Unintentional damage or

disruption of power sources

– Blockage of damaged seawater intakes

– Aggressive equipment condition monitoring


EPRI Review and Walkdown Participants

Shiego Hattori

Ken Huffman

Sam Bass

Antonio Godoy

Jim Johnson

Greg Hardy

John Richards

Gary Toman

Jim Heishman

Steve Hess

Drew Mantey


Key TEPCO Review and Walkdown Participants

Kazuyuki NagasawaGroup Manager Atsushi Taniguchi

Team Leader

Yukiko OgawaTeam Leader

Naohiro MasudaSuperintendent

Shinichi KawamuraUnit Superintendent


Together…Shaping the Future of Electricity

fukushima daini independent review and walkdown documents/action 01... · fukushima daini...

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