Extremely Confidential

What should we learn from the severe accidents at
the Fukushima Dai-ichi Nuclear Power Plant?
Final Report- Team H2O Project -December, 21st, 2011
1
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Background
Background－－ Regarding
Regardingthis
thisprojectproject －－2
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Background - Purpose

Extremely Confidential

The Purpose of This Project

11 To
Toinvestigate
investigatethe
thefacts
factsregarding
regardingwhat
whathadhadhappened
happenedininthe
theGreat
GreatEast
EastJapan
Japan
Earthquake
EarthquakeandandTsunami,
Tsunami,and
andthethesevere
severeaccidents
accidentsatatFukushima
FukushimaDai-ichi,
Dai-ichi,Dai-ni,
Dai-ni,Onagawa,
Onagawa,and
andTokai
TokaiDai-ni
Dai-niNuclear
NuclearPowerPowerPlants,
Plants,andandidentify
identifythe
thetruth,truth,issues,
issues,andandlessons
lessonstotoshare.
share.
22 Based
Basedononthe
theabove,
above,totoprovide
provideaascientific,
scientific,technical,
technical,andandlogicallogicalframework
frameworkfor
forthethediscussion
discussionand
andexamination
examinationofofthe
thepros/cons
pros/consofofre-activation
re-activationofofthe
thenuclear
nuclearpower
powerplants.
plants.
33 Research
Researchmethodology,
methodology,findings,
findings,andandconclusions
conclusionsofofthe
theprojectprojectshould
shouldbebeinternationallyinternationallyneutral
neutralandandreceive
receiveaaconsensus
consensusfrom
frominternationallyinternationallytrusted
trustedagencies
agenciessuch
suchasasthe
theIAEA.
IAEA.

3
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Background – Purpose

Extremely Confidential

In order to logically discuss the re-activation of the nuclear power plants, safetyassessment tests which live up to international accountability are essential. => As thefirst step towards that, this project covers the first phase.
Steps to judge the appropriateness of re-activation of nuclear power plants
3 months

6 months

9 months

1 yearJudgment of
re-activation• Verify the safety measures• Explain the test results to the
public• Determine re-activation, etc
3 months• Collaborate with international experts
such as the IAEA in order to gaininternational accountability
3 months

3 months
Define safety assessment test
• Investigate facts, lessons, and safetymeasures from Fukushima Dai-ichi.
• Compare them to the stress-tests of
NISA as well as of EU• Define stress test items of this project

３ヶ月necessary safety
Implement
measures & investments
Implement safety measures on theplants as a result of the test.

Conduct the test
• Gain consensus from IAEA
• Conduct tests in all 54 nuclear
plants (exclude the 6 plants at
Fukushima Dai-ichi)

Coverage of this project
It is best to judge by this winter, or at latest by this spring.
4

Source: How to Manage the Risk of Complete Shutdown of All Nuclear Reactors in Japan. (by Kenichi Ohmae)
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Background - Schedule of Research

Extremely Confidential

The project was kicked off on July 24th of 2011. The interim report was submitted on
October 28th with regards to the lessons learned from the severe accidents at
Fukushima Dai-ichi Nuclear Power Plant and the safety measures for BWR .
9月

8月

Stress Test
Events that are
ストレステスト
anticipated/planned
Accident Reportin the future

10月

12月

11月

電力stepⅠ報告（定検起動前）

電力stepⅡ報告

事故報告

事故報告（電事連）

IAEA

▼会議

事故報告（中間報告）
国・東電Stress Test Assessment

ストレステスト評価

クロノロジー整理

報告書作成

ストレステスト評価(stepⅠ）

Orientation of thisproject

報告書見直し（事故報告・ストレステスト結果反映）

報告書作成･纏め▼細野大臣説明IAEA報告･コンセンサス活動

Investigation of this phase
End of July

Information
Information
gathering.
gathering.
Preliminary
Preliminary
preparation.
preparation.

End of August

Investigate
Investigatethe
theevents
eventsatat
Fukushima
Dai-ichiandFukushima Dai-ichi andDai-ni
Dai-ni(chronology)(chronology)
Extract
Extractlessons
lessons/counter/countermeasures
measuresfrom
fromthethechronology
chronology
Investigate
Investigatecurrent
currentstressstresstests
tests
(ST)
by
EU
&
NISA
(ST) by EU & NISA

End of September

Organize
Organizelessons
lessons&&countercountermeasures
measuresto
topreventpreventthe
theaccidents
accidents
aspect・・ TechnicalTechnical aspect
・・ Accident
Accidentmanagement
management

CompareComparewith
withotherotherSTST

Make
Makeinteriminterimreportreport(on
(on
BWR)
BWR)

End of October

Final
Final
approval
approvalby
bythetheprojectproject
SubmitSubmitinteriminterimreportreport5

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Background - Schedule of Research

Extremely Confidential

Based on the findings of the interim report, the project conducted a case-study on PWR
during November and December 2011, then the final report was submitted.
Nov-Dec 2011 master schedule for this project

End of OctoberEnd of November

Investigate
Investigatekey
keyfunctions
functionsof
ofPWR
PWR
&&differences
from
BWR
differences from BWR
Summarize
Summarize
InterimInterimReport
ReportEnd of December

Make
Makecase-study
case-studydocument
documenton
onPWR
PWR

ExamineExaminethe
theapplicability
applicabilityofoflessons
learnedlessons learnedfrom
fromBWR
BWRto
toPWR
PWR
Evaluate
Evaluatecurrent
currentsafety
safetymeasures.
measures.
Case
study
on
PWR
Case study on PWRplants
plants(diversification(diversificationand
andmultiplicity)
multiplicity)

End of January

EnglishEnglishtranslationtranslation
Make
Makefinal
finalreportreport6
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Background – Project Formation

Extremely Confidential

The project formation on the BWR and interim-report was as follows:
Those who cooperated with interviews, hearings and data-gathering:

Kenichi
KenichiOhmae
Ohmae

Electric
ElectricGroupGroup● Japan Nuclear Fuel Ltd. Managing Director and Executive
General Manager, Corporate Planning Office,Mr. Harukuni Tanaka● Tokyo Electric Power Co., Inc. General Manager, Nuclear
Power Plant Management Dept., Mr. Takeshi Takahashi

Toshiba
ToshibaHead
HeadOffice
Office● TOSHIBA CORPORATION Power System Company
Chief Specialist, Fukushima Restoration Project Engineering
Dept., Nuclear Energy Systems & Service Div.,
Mr. Shigeru Yukinori and 2 others● Ohmae and Associates, Inc.
Partner, Mr. Iwao Shibata● Japan Nuclear Fuel Ltd.
General Manager,
Reprocessing Planning Dept.,
Reprocessing Business Div.,Mr. Manabu Yusa

● TOSHIBA CORPORATION Power Systems Company
Senior Manager, Fukushima Restoration Project Engineering
Dept., Nuclear Energy Systems & Service Div.,Mr. Mamoru Hatazawa

Hitachi
Hitachi● Hitachi-GE Nuclear Energy, Ltd. Corporate Chief Engineer,
Mr. Kumiaki Moriya● Hitachi-GE Nuclear Energy, Ltd. Professional Engineer andChief Project Manager, Nuclear Plant Engineering Dept.,
Next Generation Reactor Center,
Mr. Masayoshi Matsuura

7
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Background…Project Formation: PWR

Extremely Confidential

The project formation on the PWR are the following:Those who cooperated with interviews, hearings and data-gathering:

Kenichi
KenichiOhmae
Ohmae

KansaiKansaiElectricElectricPower
Company
Power Company● Kansai Electric Power Co., Inc. Manager, Nuclear AccidentManagement and Nuclear Power Div., Mr. Kensuke Yoshihara● Kansai Electric Power Co., Inc. Project Manager, Plant &Maintenance Engineering Group, Nuclear Power Div.,Mr. Toshihiko Tanaka● Kansai Electric Power Co., Inc. Tokyo Office
Manager, Mr. Toshikazu Sendo
Assistant Manger, Mr. Takahiro Ohgami

Head
HeadOffice
Office● Ohmae and Associates, Inc.
Partner, Mr. Iwao Shibata● Japan Nuclear Fuel Ltd.
General Manager,
Reprocessing Planning Dept.,
Reprocessing Business Div.,Mr. Manabu Yusa

Mitsubishi
Mitsubishi
Heavy
HeavyIndustries
Industries● Mitsubishi Heavy Industries, Ltd. Acting Manager,
Advanced Plant Safety Dept., Nuclear Energy Systems Div.,Mr. Daisaku Okuno

8
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Background – Project Scope

Extremely Confidential

The research focused on the technical aspect of the events and accidents, including
the hydrogen explosion and dispersion of radioactive materials, in order to identify
safety measures for the plant safety as well as the local safety.
Main scope of the research● Damage of the earthquake and tsunami disaster.
● Chronology of the events at the Fukushima Dai-ichi Nuclear Power Plant● Chronology of the events at the other plants (Fukushima Dai-ni, Higashidori, Onagawa, Tokai Dai-ni).
● Differences in the chronologies between Fukushima Dai-ichi and the other plants, and their causes.
● Loss of power supply.
● High-pressure cooling function.
● Ventilation function.
● Low-pressure cooling function.
● Hydrogen explosion (mechanism of hydrogen generation, leakage, and explosion).
● Effect, limits, and issues of existing accident management (AM).
● Issues, causes, and safety measures implied from the chronologies and analysis.
● Safety measures to prevent recurrence.
● Comparison to stress tests of NISA and EU.
● Cooperation with IAEA, etc.
Out of scope● Important/related events and issues outside of the nuclear plants.
- Actions and decision-making of the central government and relevant ministries- Actions and decision-making of the local governments● Policies and decision making of evacuation, its zoning, and compensations for damage.

9

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima
FukushimaDai-ichi
Dai-ichiNuclear
NuclearPowerPowerPlant
Plant
・・ What
Whathappened?
happened?
・・ WhatWhatarearethetheimplications?
implications?

10
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Details
Detailsof
ofthe
theEarthquake
EarthquakeandandTsunami
Tsunamion
on
th
March
(atFukushima
FukushimaDai-ichi)
Dai-ichi)March1111th(at・・ Scale
Scaleandanddamagedamagecaused
causedby
byearthquake
earthquakeandandtsunami
tsunami・・ ItsItsimplications
implicationsof
ofthe
thedamagedamageon
onthe
theplant
plant

11
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Overview of Fukushima Dai-ichi: With 6 reactors, it is one of the oldest plants in Japan,
and its operation started about 40 years ago. Of 6 reactors, No. 1 - 3 were the oldest,
located at the lower altitude, and only under regular operation on March 11th.
Unit 6
Seismic isolation tower
Unit 5Main Gate

Unit 1
Unit 2
Unit 3
Unit 4

Location

Okuma
Town

FutabaTown

BWR-3

Output(10,000 kW)
46.0

Main
contractor
GE

Unit 2 1974.7
Unit 3 1976.3

BWR-4
BWR-4

78.4
78.4

GE/Toshiba
Toshiba

Unit 4 1978.10

BWR-4

78.4

HitachiOperation
started in
Unit 1 1971.3
Unit

PCV Type

Unit 5 1978.4

BWR-4

78.4

Unit 6 1979.10

BWR-5

110

Toshiba

Operation status at the time of earthquake
Under regular operation
Under regular operation
Under regular operation
Regular All fuel removed. Pool gate closed
Inspection （Under shroud exchange）
RegularInspection Reactor pressure vessel was sealed

Regular
12
GE/Toshiba Inspection Reactor pressure vessel was sealed
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Type of Primary Containment Vessel: The Mark-I and Mark-II were used at Fukushima
Dai-ichi Plant.
Fukushima Dai-ichi Unit 1（Output 460,000kW）"1971”

Dai-ichi Units 2-5（Output 784,000kW）"1974～1978”

BWR-3
Mark-I（Flask form）

BWR-4
Mark-I（ Flask form ）Dai-ichi Unit 6
Fukushima Dai-ni Unit 1（Output 1,100,000kW）"1979-1985”

BWR-5
Mark-II（Circular）

Fukushima Dai-ni Units 2-4（Output 1,100,000kW）"1984-1994”

BWR-5
Mark-II Improved（Hangar shape）

13
Fukushima Dai-ni Unit 1
Source：NRC Homepage

Fukushima Dai-ni Unit 3

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Tohoku Region Pacific Coast Earthquake: A gigantic earthquake, magnitude 9.0, occurredat 14:46 on March 11th (Fri), 2011. Intensity around the Fukushima Dai-ichi exceeded 6.5.
●●

Date of earthquake：
2:46 PM, March 11th (Fri), 2011
Location of hypocenter： Off the Sanriku Coast （North latitude 38、East longitude 142.9） Depth 24km、Magnitude 9.0●

Scale in each location：

Intensity 7：
Intensity upper 6:
Intensity lower 6:
Intensity lower 5:
Intensity lower 4:

Miyagi-ken Kurihara-shi
Fukushima-ken, Naraha-cho, Tomioka-cho, Okuma-cho, Futaba-cho
Miyagi-ken, Ishinomaki-cho, Onagawa-cho, Ibaragi-cho; Ibaragi-ken, Tokai-mura
Niigata-ken, Kariha-mura
Rokkasho village, Higashidori village, Mutsu city (Aomori pref.),
Ohma town, Kashiwazaki city (Niigata pref.)Reported on 14:53, March 11th, 2011

震源 hypocenter
原子力発電所 Fukushima Dai-ichi and Dai-ni Plants
Magnitude

14
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

After the earthquake, a powerful tsunami occurred along the coasts of Miyagi and
Fukushima. At 15:27 of March 11, about 40 minutes after the earthquake, the first wave
hit Fukushima Dai-ichi. 8 minutes later (15:35), the even higher 2nd wave hit.
Tsunami height in each location

Soma City

Leg
end
:M

As of March 13th, 8:00AM
axim
um

heig

ht o

f tsu

nam
i (m
)

Source：Meteorological Bureau Homepage

15

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Scale of earthquake and tsunami: The earthquake and tsunami that hit Fukushima Daiichi were among the fourth largest in the recorded history.
Earthquake Magnitude ＝＞ 4th in recorded history
Rank

Year

Name of Earthquake

Magnitude

１

１９６０

Ｃｈｉｌｅ

９．５

２

１８６４

Ａｌａｓｋａ

９．２

３

２００４

Ｓｕｍａｔｒａ

９．１

4

2011

Tohoku Region Pacific Coast

9.0

４

１９５２

Ｋａｍｃｈａｔｋａ

９．０

Tsunami Magnitude*＝＞ 4th in recorded history
Rank

Year

Name of Earthquake

Magnitude

１

１９６０

Ｃｈｉｌｅ

９．４

２

１８３７

Ｖａｌｄｉｖｉａ，Ｃｈｉｌｅ

９．３

２

１９４６

Ａｌｅｕｔｉａｎｓ

９．３

4

2011

Tohoku Region Pacific Coast

9.1

４

１９６４

Ａｌａｓｋａ

９．１

６

２００４

Ｓｕｍａｔｒａ other

９．０
16* Tsunami Magnitude = Calculated from the scale of tsunami caused by the earthquake

Source: Homepage of Laboratory of Seismological Study, Tokyo Univ.
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Damage by the earthquake such as the liquefaction and break of infrastructure was larger
at Fukushima Dai-ichi (Intensity: upper 6*) than at Dai-ni (lower 6*). One of the major
factors which had retarded the accident management at both plants afterwards.
Damage at Fukushima Dai-ichi● Road is completely cracked and fissured● Major bend in guardrail● Many cracks along the side of the road
● People and vehicles can hardly pass*: Maximum acceleration at Dai-ichi was 550gal (east to west) and 350gal at Daini (up to down). Both observed at the lowest floors of the reactor buildings.

● Road has caved in for several meters● Drum can has rolled into the middle of the street● No cars can pass. People can hardly walk● Several meters of chasm even at elevated ground17● Ground has caved in

Damage at Fukushima Dai-ni● Gap between building and ground (a depression in ground?)Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Though safety measures to Tsunami were implemented, based on the evaluation by JSCE
(Japan Society of Civil Engineers) in 2002, the Tsunami greatly exceeded its assumption (approx. 10m),
especially at Fukushima Dai-ichi. 3 times higher than expected.
Design conditions against tsunami to present* At construction of the plant: The design conditions were determined based on the past tsunami records.
* In 2002: Based on “Tsunami evaluation technique for Nuclear Power Plant” published in the same year by JSCE, the conditions
were reviewed, and the safety measures such as to set the seawater pumps in higher place had been implemented.

At construction

Review in 2002

Altitude (O.P.)+3.1m

Altitude (O.P.)+5.7m

DeclineSame -1.9m

Same -3.6m

Altitude (O.P.)+11.5 ~ +15.5m

AscentSame +3.7m

Same +5.2m

On the seaside area

AscentFukushima
Dai-ichiFukushima
Dai-ni

Tsunami at this time
(Height of submergence)
On the seaside of main buildings

Same +6.5 ~ +7m
DeclineSame -1.9m

Same -3.0m

Concentrated run on south road of main buildings
Altitude (O.P.) ＋12 ~ 14.5m● Difference of 5.8 ~ 9.8m from the design condition (about 3 times higher)
O.P.
= Onahama Port Construction Reference Plane
T.P.
= Tokyo bay standard sea level
O.P. is 0.727 meters below T.P.

● 1.3 ~ 1.8m of difference at Fukushima Dai-ni

18

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

The tsunami swallowed not only the seaside, but the whole area of Dai-ichi, including themountain side. Both the reactor and turbine buildings were completely inundated. => Thesafety allowance against tsunami is obviously underestimated.
Maximum tsunami height (estimation)

Actual inundation height= + 5.7m= + 11.5 ~ 15.5m● A heap of rubble in the area of 4m altitude. Hardly transport
vehicles, personnel, or supplies.

19● Even at an elevation of 10m, cars had drifted. Even on the mountain side of the building,a 5.5m-height tank has been swallowed up, just like a swimming pool.

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

The moment the tsunami hit: The wave, that reached at the plant, surpassed the reactor
building (45 m), and came halfway up the exhaust stack (120 m).
Fukushima Dai-ichi

Exhaust Stack

Nuclear Reactor
Building

20
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

The Scar of Tsunami: On the south side of the plant, the forestation along the shore
has been torn up from their roots.
Before March 11th (Fukushima Dai-ichi Power Plant, south side of unit 4)

Forestation has been torn up
from their roots
After March 11th

21
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Aerial shot of Fukushima Dai-ichi: Of the 6 reactors, the units 1 - 3 were in regular
operation. The units 4 - 6 halt for regular inspection.
Unit 1（In operation）

Unit 2
Unit 3
Unit 4（In operation） （In operation） （Under regular inspection）

Unit 5（Underregularinspection）
Unit 6（Underregularinspection）

22（(C) GeoEye
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Ground height: Units 1, 2 and 3 (all in operation) are 10m above sea level and at alower level than Units 5 and 6 (both at 13m).

Seaside of Units 1-4
Ground height：O.P. 4m

Seaside of Units 5/6
Ground height： O.P. 4m

Wharf, Cask bldg
Ground height： O.P. aprx. 5m

Main building of units 5/6
Ground height： O.P.13m

Main building of Units 1-4
Ground height： O.P. 10m

23
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved（(C) GeoEye

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Units 1-6 of Dai-ichi and the main facilities were all submerged due to the 15.5m tsunami.
Photos of page 27, 28.
( Solid waste storage)

Photos of page25, 26.
( Near exhauststack of Unit 4)

Fukushima Dai-ichi Nuclear Power Plant.
Submerged areas are in blue color

24（(C) GeoEye

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

The tsunami easily has swallowed up the heavy fuel tank (5.5m), and the whole yard
has become like a swimming pool with full water.
Heavy fuel tank (height 5.5m)

Flooding of the yard at Dai-ichi(near Unit 4 exhaust stack. Ground height O.P.+10m)

3 carsDate of capture ：2011/3/11 15:42

Same 15:42

Same 15:43

Same 15:43
Heavy fuel tank has been swallowed

The whole yard has become like aswimming pool with full of water.

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Same 15:43

Same 15:44
The white car that was on the left side of25
the picture has been swept aside and is
now stuck in the outer wall of the building

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Flooding (continued): The 3 vehicles were completely drifted by the tsunami.
Flooding of the yard at Dai-ichi(near Unit 4 exhaust stack. Ground height O.P.+10m)

Date：2011/3/11 15:44

Same 15:44

Same 15:46

Several cars in the first photo
have been completely drifted.
One of those vehicles is now
stuck into the building’s wall

Same 15:49

Same 15:57

26
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Seaside at the moment the tsunami hit: Tsunami easily overcame the 10m levee,drifted a number of cars, and almost completely swallowed the giant tank.
East side of solid waste storage (southeast seaside of unit 5)①②
Tsunami easily
flooding overthe 10m levee.

③④

Giant surge tankof photo 3 issubmerged up to
here.
Cars are driftedfrom elsewhere

27
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ichi(Continued) The 2 heavy fuel tanks have been drifted onto the road. The side of the surge
tank has been bent like a twisted PET bottle.

⑤⑥

2 heavy fuel tanks have been drifted, andpushed up towards the roadside.

The entire body of the giant surge tank has been
contorted as if a PET bottle is wrenched

28

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

The 11.5~15.5m tsunami hit the entire plant with 4-5m of water flooded. As the units 1 - 4
were lower than units 5 & 6 in terms of the ground level, their damage was more serious.
Fukushima Dai-ichi Nuclear Power Plant：
Immersion depth & height

2 out of 3 extra high voltage
switching stations, which
supply the reactors with theexternal power, were
flooded by the tsunami

Appendix
Red: Immersion height( ( ) = immersion depth )Blue: Run height

Tidal station

Tsunami heightRun height
Immersion depth, height
Onahama Port Construction Reference Plane

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Immersion area

・ Immersion height: Height from the O.P.
reference plane, at which traces of discoloration
or driftage are left in buildings or facilities.
・ Immersion depth: Height from the ground level,at which traces of discoloration or driftage areleft in buildings or facilities.

29

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Drifted facilities & structures: (1) Seaside of Units 1-4: The heavy fuel tank was carried
away, and a large crane was moved. The countless damage and drifts.

Aerial photo of seaside of Fukushima
Dai-ichi Units 1-4
Light=> Awai to sea

Light=> Awai to sea

Light=> Awai to sea

A heavy fuel tank has
been carried away

Curtain wall damaged

Light=> Awai to sea

South breakwater=> Drifted to sea

Wave extinguish block=> Away to sea

Seawater pump=> Drifted to sea?

Screen cover(temporarily placed)

Heavy oil tank=> Drifted to sea?
Concrete hatch=> Drifted to sea?
Circulation water pump
Drifts concentrated

Cooling tower ofcirculation pump=> Drifted to sea?

PP fence =>Slanted to seaside

Container of staff room for unit 4=> Drifted to sea?

Circulation water pump

Storage => Seaside wall
moved to south side?

Arcade=> Destroyed

Arcade=> Destroyed

550t rafter crane
PP gateReversible valve pit=> Many drifts

A large cranehas been
moved
Arcade=> Destroyed

Reversible valve pit=> Many drifts
Reversible valve pit=> Many drifts

PP fence => Fallen
down to seaside

Heavy oil tank

A ship (from elsewhere)

Note: Magnified pictures of the heavy fuel tank and the large crane are on the next page.

30
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential(Continued) Myriads of rubbles, drifts, and damage made it extremely difficult to transport
people and supplies after the tsunami.

A heavy fuel tank has beendrifted, and has completely
blocked the road.

A drifted car is stuck
between the pipes andbuilding.

Crane vehicle (45t) anddebris have been drifted,
and obstructed the accessto the building

31
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Drifted facilities & structures: (2) Mountain side of Units 1-4: Container’s cornice coverhas drifted over one hundred meters, and numerous containers are scattered about.

Places located far
from the ocean are
also submerged
Aerial photo of the mountain side of Fukushima Dai-ichi Units 1-4

Cornice coverof container

Cornice coverof container
Cornice coverof container

Containers
scattered32
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Drifted facilities & structures: (3) Seaside of Units 5 and 6: Even at units 5 and 6 where
the ground level was higher, the seawall was damaged and countless tetra pods were
stranded on it, making traffic access along the seawall impossible.

Seawall damaged
Aerial photo of seaside of Fukushima Dai-ichi’s Unit 5-6

Revetment => Destroyed& drifted to sea

Upper parts of eastseawall => Destroyed& drifted to sea

Portal craneWave-eliminating
sea bank => drifted to sea

Staff rest room=> Drifted to sea?

Drifts concentrated
Heavy oil tank

PP fence

33
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Flooding on the mountain side swallowed the power supply systems of Units 1-4 by salt
water. The liquefaction of the roads, landslides, and rubble had made thetransportation of people and supplies significantly aggravated and extremely difficult.

① A large amount of seawater
flowed into the switching station
at the mountain sideof the exhaust stack , andcompletely destroyed the power
supply systems.

①②② Landslides and rubble by thetsunami made thetransportation of people andsupplies extremely difficult.

34
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Damage of Tsunami: An oil fence is stuck into the building. The road is severely liquefied.
Along with scattered debris, it is far from passable during the day, and impossible to walkduring the night without light.

Surroundings of storage/cask buildings

Oil fence is stuck in thebuilding

Several-meter large pieces
of asphalt or concrete debris
are drifted, fractured, andscattered around.

Road is severely liquefied

35
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Damage of Tsunami: In the storage and cask buildings, a car was swept in and stuck
vertically. Heavy debris is strewn over. There is no walking space.

Inside of storage/cask buildings

A car was swept in and stuck vertically in the ground

Debris and furniture are completely strewn over thefloor. No place for foothold.

36
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Damage of Tsunami: Power boards of Unit 4 turbine building. Tires, vacuums, hoses, andother numerous debris have piled up and scattered around. The boards are inaccessible

Power boards in the turbine building of Unit 4● They need toinvestigate thedamage to each power
supply system by theearthquake/ tsunami,
and take recovery
actions.
● However, the debris
are scattered around,and simply accessing
the power board is achallenge.

37
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi…External Factors made operation difficult (outside building)

Extremely Confidential

Liquefaction, numerous debris, and fractures of roads have made transport of people andsupplies extremely difficult. Furthermore, the complete darkness at night has made thework environment extremely hard.
• Extremely bad access by frequent aftershocks, opened manhole, chasms, cave-ins, and liquefaction of the ground• Complete darkness at night• Access routes were extraordinarily obstructed.

Cave-ins of roads
Even walking is dangerous,
especially so at night.
Obstacles in access route
Access is circumvented bystrewn fire hoses. After the
explosion, further obstruction
by debris, and damaged fire
trucks are added.
Access to temporary
power supply systems
They used heavy machinery to
break down the loading
entrance for access to thebuilding.
Wood fromshutter
destruction

Setting up of makeshift
power supply cables
Cables are moved by the staff
of not only power company
but also other firms.

38
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi…External Factors made operation difficult （aftershock）

Extremely Confidential

Furthermore, highly frequent aftershocks significantly interrupted and hindered recovery
operations. Compared to the past major earthquakes, about 4 times many aftershocks
had occurred.
Number of aftershocks of major earthquakes in ocean areas(Over 5.0 magnitude, including main earthquake.)
As of 15:00, May 13, 2011
Tohoku Region Pacific Coast Earthquake (M 9.0. 2011)

Number of aftershocksof this earthquake on
March 11.

Accumulated
numbers

Hokkaido East Coast Earthquake (M 8.2. 1994)

Sanriku Earthquake & Tsunami (M 8.1. 1933)
Tokachi Coast Earthquake (M 8.2. 1962)

Press release ofMeteorological bureau(May 13th, 2011)

Tokachi Coast Earthquake (M 8.0. 2003)
Sanriku Haruka Coast Earthquake (M 7.5. 1994)

Number of days after main earthquake

Number of aftershocks ofmajor earthquakes in the past

39
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi…External Factors made operation difficult （inside building）

Extremely Confidential

With loss of power, in the building was pitch dark, making monitoring the reactor
extremely hard. Strewn rubble has further obstructed the field work for recovery.
• Due to power loss, they had to operate under complete darkness in the building.
• Due to power loss, they installed makeshift batteries to monitoring instruments.
Operations in thedarkness
Photo of the service building
entrance from inside. Debris
strewn on the floor.
Makeshift batteries
for instruments
Connected makeshiftbatteries for monitoring
instruments.
Monitoring ofparameters and data
Monitoring parameters in
the dark with hand lights.
Direction by Duty Chief
Duty chief at desk in thedarkness with full mask.
40
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi…External Factors made operation difficult (Radiation Dosage)

Extremely Confidential

Furthermore, the radiation levels have continued to rise and interrupted the recovery
operations in the fields.
Radiation level in front of the double-entry doors to Unit 1
turbine building along the Pine Hallway (March 11th, 12th)

Pine hallway

P.N

Double-entry doors

Measured around 23:00,
March 11th

1.20mSv/h
0.90mSv/h

Measured on
March 12th, 2:05

0.50mSv/h
Double-entry doors
Nuclear reactor building

0.45mSv/h
Turbine building
Control
Building

Radioactive waste building

Service Building for Unit 1&2

41

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Voices of the field staff (1) - The extremely severe and dangerous working environment
without any make-up.
 “…Power indicators flickered, and they went out one by one in front of my eyes. At thetime I didn’t think it was by tsunami, and had no idea what had just occurred.” “…Unit 2 was pitch dark, Unit 1 had only emergency lighting (dim light). I thought we hadlost power and were unable to do anything.”
 “…young operators seemed worried, and wondered ‘if we are unable to operate, and can do
nothing, is there a reason for us to be here?’, but I begged them to remain. I told 2 young
trainees to evacuate to the seismic isolation tower, and I asked the remaining others ‘is this okay withyou all?’” “… I wrote out the names of people who could go to the vent, and organized so that a shift manager
would be allotted. As they would be going to a place of very high radiation with fully
equipped, I did not send the young people.” “…Normally, the cable installation takes 1 to 2 months. That we did it in several hours iskiller speed. In the pitch dark, we had to find the penetration for installation, or perform terminal
processes. Normally a machine would be used, but this time a heavy cable was installed bymanpower.” “Lots of time was spent with direct communication even between headquarters and the field asalmost all the communication lines were lost. For example, it took much time even to send thecommand "measure resistance by megger”.
42
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Voices of the field staff (2) “…A considerably large aftershock occurred, and I desperately ran back.”
 “…I placed my foot on the torus, not on the catwalk. Since the valve was on top, I placed my foot on
the torus to check its heat, and (the black boots) melted down. I determined that it would besafer not to walk there”

 “…It was not easy even to go to the reactor building (RCIC room). There were extra hassles suchas 10-15 minutes to put on the protective suit, 30 minutes to work in the field, and took
off the suit and went to the operation room for reporting.”
 ”…Communication means were unavailable, and it took me 45-60 minutes just to get to the
RCIC room and back.“
 “…I thought instruments could be revived only with batteries, so all the members were
set to looking for some. Tried to create at least the bare minimum parameters. It is not
something that is usually predicted, but we tried to at least think of something we cando.” “… The battery was very heavy and it was tough to transport. No connection tools, nomeans of communication. No worse condition than that.”
43
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ichi

Extremely Confidential

Summary: Earthquake and Tsunami that hit Fukushima Dai-ichi wreaked huge damage
to the on-site work environment. It was a major background reason for delay/failure ofrecovery actions to prevent the core damage and hydrogen explosion.
Effects of earthquake & tsunami on the work environment at Fukushima Dai-ichi Units 1-4●● Darkness：
Darkness： Almost
Almostallallinside/outside
inside/outsidelights
lightsfailed
faileddueduetotoAC/DC
AC/DCpower
powerloss,
loss,andandthethesitesitewaswasplunged
plungedinto
intodarkness.
darkness.
●● LossLossofofcommandcommandcenter
centerfunctions:functions: Almost
Almostallalldatadataincluding
includingthe
thenuclear
nuclearreactor
reactortemperature,temperature,pressure,pressure,and
and
water
level
becameunavailableatthecentralcontrol
room
due
to
loss
of
power
(gauging
andcontrolequipments
water level became unavailable at the central control room due to loss of power (gauging and control equipmentsnot
notworking)working)●● Communication
Communicationmalfunction,
malfunction,command
commanddifficulty:
difficulty:In
Inaddition
additiontotothe
thedisruption
disruptionof
ofthe
thelineslinesforforfixed
fixedphones
phonesandandcellphones,the
PBX
foremergency
PHS
did
not
function
fully
due
to
loss
of
power.
This
madecommunicationandcell phones, the PBX for emergency PHS did not function fully due to loss of power. This made communication andcommands
commandsbetween
betweenthe
thecentral
centralcontrol
controlroom
roomandandon-site
on-siteteams,
teams,asaswellwellasasreporting
reportingthe
theplant
plantstatus
statusandandrequests
requestsfor
foraidaid
totooffsite
offsiteextremely
extremelydifficult.
difficult.
●● Difficulty
Difficultyof
oftransportingtransportingpersonnel/supplies：
personnel/supplies： Due
Duetotothe
thecombinations
combinationsof
ofdarkness,darkness,cave-ins/cave-ins/shredding/shredding/liquefactionoftheroads,
myriads
ofdebris,andblockadeofelectric
gates
andentrances,thetransportationliquefaction of the roads, myriads of debris, and blockade of electric gates and entrances, the transportationof
ofpersonnel
personnel
andsupplieswasextremely
difficult.
and supplies was extremely difficult.
●● Extremely
Extremelybrutal
brutalwork
workenvironment：
environment： Interruptions
Interruptionsand
andretreat
retreatfrom
fromoperations
operationshappened
happenedmany
manytimes
timesatat
unforeseen
unforeseenpoints,
points,due
duetotonumerous
numerousaftershocks
aftershocksand
andradiation
radiationlevels
levelsthat
thatexceeded
exceededacceptable
acceptablesafe
safelimits.
limits.
●● Limitations
Limitationsin
inmovement
movementand
andtime：time： There
Therewaswasaalacklackofofprotective
protectivegear,
gear,masks,
masks,individual
individualdosimeters
dosimetersetc,
etc,andandnotenoughpersonnel
could
work
for
on-siteoperations.
not enough personnel could work for on-site operations.
●● Shredding/isolation
Shredding/isolationof
ofsupplies：
supplies： 11of
ofthe
the33fire
firetrucks
truckswas
wasdamaged
damagedby
bythe
thetsunami,
tsunami,and
andanother
anotherwas
wasisolated
isolatedatat
Unit
44
Unit5&6
5&6andandunable
unabletotoleave.
leave.Eventually
Eventuallyonly
only11fire
firetruck
truckwaswasavailable
availablefor
foruseuseatatUnits
Units1-4.
1-4.
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Details
Detailsof
ofthe
theEarthquake
EarthquakeandandTsunami
Tsunamion
on
th
March
(atFukushima
FukushimaDai-ni)
Dai-ni)March1111th(at・・ Scale
Scaleandanddamagedamagecaused
causedby
byearthquake
earthquakeandandtsunami
tsunami・・ ItsItsimplications
implicationsof
ofthe
thedamagedamageon
onthe
theplantplant

45
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Extremely Confidential

Overview of Fukushima Dai-ni: With a total of 4 nuclear reactors, it was activated in 1982,
11 years after Dai-ichi. At the time of the earthquake, all 4 reactors were in operation.

Unit 4
Unit 3

Seismic isolation tower

Unit 2
Unit 1

Location

Unit

Operation
started in

PCV type

Output(10,000kW)

Main contractor

Operation status
at the time of earthquake

NarahaTown

Unit 1

1982.4

BWR-5

110.0

Toshiba

Under regular operation

Unit 2

1984.2

BWR-5

110.0

Hitachi

Under regular operation

Unit 3

1985.6

BWR-5

110.0

Toshiba

Under regular operation

Unit 4

1987.8

BWR-5

110.0

Hitachi

Under regular operation
46

Tomioka
Town

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Extremely Confidential

Type of Primary Containment Vessel: Mark II was used at Fukushima Dai-ni, a newer typethan that of Dai-ichi.
Fukushima Dai-ichi Unit 1（Output 460,000kW）"1971”

Dai-ichi Units 2-5（Output 784,000kW）"1974～1978”

Dai-ichi Unit 6
Fukushima Dai-ni Unit 1（Output 1,100,000kW）"1979-1985”

BWR-3
Mark-I（Flask form）

BWR-4
Mark-I（ Flask form ）BWR-5
Mark-II（Circular）

Fukushima Dai-ni Unit 1
Source：NRC Homepage

Fukushima Dai-ni Units 2-4（Output 1,100,000kW）"1984-1994”

BWR-5
Mark-II Improved（Hangar shape）

47
Fukushima Dai-ni Unit 3

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Extremely Confidential

At Fukushima Dai-ni, compared to the design condition of 5.2m, a 6.5~7m tsunami hit.
The difference from the condition is smaller than that at Dai-ichi.
Design conditions against tsunami to present* At construction of the plant: The design conditions were determined based on the past tsunami records.
* In 2002: Based on “Tsunami evaluation technique for Nuclear Power Plant” published in the same year by JSCE, the conditions
were reviewed, and the safety measures such as to set the seawater pumps in higher place had been implemented.

AscentFukushima
Dai-ichiFukushima
Dai-niAt construction

Review in 2002

Altitude (O.P.)+3.1m

Altitude (O.P.) +5.7m

Tsunami at this time
(Height of submergence)
On the seaside of main buildings

DeclineSame -1.9m

Same -3.6m

Altitude (O.P.)+11.5 ~ +15.5m

AscentSame +3.7m

Same +5.2m

On the seaside area

Same +6.5 ~ +7m
DeclineSame -1.9m

Same -3.0m

Concentrated run on south road of main buildings
Altitude (O.P.) ＋12 ~ 14.5m● Difference of 1.3 ~ 1.8m from the design condition
O.P.
= Onahama Port Construction Reference Plane
T.P.
= Tokyo bay standard sea level
O.P. is 0.727 meters below T.P.

● Smaller than that of Dai-ichi (5.8 ~ 9.8m)

48

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Extremely Confidential

As a result, the tsunami damage at Dai-ni was limited compared to Dai-ichi. The groundheights are either 4m or 12m above sea level. The reactor & turbine buildings were at 12m.
Maximum tsunami height (estimation)

Actual inundation height= + 5.2m= + 7m(14m only at south side of unit 1)● On the sea side, 4m above sea level, debris is scattered as in Dai-ichi, and it
is extremely difficult to transport vehicles, personnel, or supplies.

● At 12m above sea level, breakage of buildings, facilities, or scatteringof debris can barely be seen.

49

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ni

The immersion height was 7m overall, though it was 14m in the south side of Unit 1,
where a concentrated run occurred. Less immersion around the nuclear reactor
buildings compared to Dai-ichi.
Fukushima Dai-ni Nuclear Power Plant：
Immersion depth & height
Spot where tsunami had
a concentrated run

Angle of tsunami impact

Red: Immersion height( ( ) = immersion depth )Blue: Run height

Appendix

Tidal station

Tsunami heightRun height
Immersion depth, height
Onahama Port Construction Reference Plane

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Immersion area

・ Immersion height: Height from the O.P.
reference plane, at which traces of discoloration
or driftage are left in buildings or facilities.
・ Immersion depth: Height from the ground level,at which traces of discoloration or driftage areleft in buildings or facilities.

50

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Extremely Confidential

Fukushima
Aerial shot of Fukushima Dai-ni before the tsunami: All 4 nuclear reactors were in Dai-ni

operation.

Unit 4(In operation)

Unit 3(In operation)

Unit 2(In operation)

Unit 1(In Operation)

51
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved（(C) GeoEye

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Ground height: – The 4 reactors of Dai-ni were at 12m above sea level. The sea side
where the seawater cooling systems are located is at 4m (above sea level). The immersion
height was 7m (above sea level).

Sea side area
Ground height：O.P.4m

Main building area
Ground height：O.P.12m

Fukushima Dai-ni Nuclear
Power Plant
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

52（(C) GeoEye

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ni

As the grounds of the reactors are higher than tsunami, direct submersion is limited.
However, by the concentrated run of tsunami along the south road of Unit 1, thesurrounding area of the nuclear reactors was immersed.
Immersion by tsunami on the seaside is limited

Concentrated
run
Unit 1

Seismic
Isolation
Tower

53
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved（(C) GeoEye

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Extremely Confidential

Damage of tsunami: It is concentrated at the south side of unit 1, along with theconcentrated run, and the sea side where the ground level was low.

Tsunami, that directly
hit Unit 1’s south road,ran up to a maximum
height of 14m. The
water flowed around tothe back of the nuclear
reactor.

At the sea side, where the grounds were at 4m, heavy damage
was caused by the tsunami, and debris is scattered everywhere

As the reactor & turbine buildings were at 12m, they were notdamaged very much by the 7m tsunami.

54

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Reality of Earthquake and Tsunami - Fukushima Dai-ni

Damage of tsunami (continued): Tsunami ran up along the south road and flooded into
Unit 1 from the intake duct of its annex building.
① Outside of Unit 1’s emergency bellows room
Immersed from the intake louverof the reactor annex building.

② Inside of emergency bellows room

③ Emergency DG control room (System A)

Though immersed, there was no scatter of
fixtures and facilities with no numerous
debris as was in Dai-ichi.
55
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima
FukushimaDai-ichi
Dai-ichiPowerPowerPlant:
Plant:
Chronologies
ChronologiesandandIssues
Issues56
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Chronology - Power Loss

Extremely Confidential

By the earthquake all external power was lost at Fukushima Dai-ichi. Switching stations
and steal towers in the plant, as well as the substations outside were damaged.
Furthermore, several power boards were flooded by Tsunami, making the situation worse.
Extra high voltage
switching station(only power transmission)

Receiving facilities on site (Units 5, 6)
Receiving facilities on site (Units 5, 6)=> Stopped due to earthquake=> Stopped due to earthquake
・・ Transmission
Transmissionsteel
steeltower
towerconnectedconnectedtoto
switchingstationtoactivateswitching station to activateunits
units55andand66(steel(steeltower
towerno.27):
no.27):Fallen
Fallendown
downbybyearthquake
andunabletoreceiveelectricity.
earthquake and unable to receive electricity.

Steel towerfell down
Breaker damaged

Control panel flooded

Receiving
Receivingfacilities
facilitieson
onsitesite(Units(Units1-4)
1-4)=>
Stoppeddue
toearthquakeand=> Stopped due to earthquake andtsunamitsunamiShin Fukushima
Substation

・・ ExtraExtravoltage
voltageswitchingswitchingstation
stationfor
forUnitUnit11andand2:2:Its
Itsbreakers
breakerswere
weredamaged
damagedby
byseismic
motion,anddisabled
toreceiveseismic motion, and disabled to receive
electricity.
electricity.

Breaker damaged
Shin Iwaki
Switching Station

・・ ExtraExtravoltage
voltageswitchingswitchingstation
stationfor
forUnitUnit33andand4:4:Control
Controlpanels
panelswere
weresubmergedsubmergedby
byTsunami,anddisabled
toreceive
Tsunami, and disabled to receive
electricity.
electricity.

Tomioka
Substation

Transmission
Transmissionfrom
fromShin
ShinFukushima
Fukushimasubstation
substation=>=>Stopped
Stoppeddue
duetotoearthquake
earthquake
・・ Facilities
Facilitiessuch
suchasasbreakers
breakerswere
weredamaged
damagedby
bystrong
strongseismic
seismicmotion.
motion.
・・ Stopped
Stoppedtransmission
transmissionlines:
lines:44lines
linesofof22systems
systems(275kV)(275kV)totounits
units1~4,
1~4,andand22lines
linesofof11
system(66kV)
to
units
5
and
6.
system (66kV) to units 5 and 6.

57

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Chronology - Power Loss

Extremely Confidential

Loss of external/internal power after tsunami: Along with loss of all external power,
all internal power sources (emergency DG*) were lost due to submergence except forthe one at Unit 6. (*: diesel generator)
Ohkuma line 4L

Ohkuma line 3L

Ohkuma line 2L

Ohkuma line 1L

External power
stopped・ Stopped due to earthquake andsubsequent damage (by soil
avalanche)

Internal power
lost

Ｄ/Ｇ

4B

・ After the earthquake, emergency DG supplied
power, but lost due to tsunami.
・ Only DG (6B) was active.

D/G

D/G

D/G

4A

3B

3A

Night forestline 2L

For transmission

D/G

2B

D/G

D/G

D/G

2A

1B

1A

Night forestline 2L

For transmission

Only internal
power left
(Emergency DG): Stopped due to earthquake: Stopped due to tsunami: Active after tsunami

5A D/G
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

5B D/G

H D/G

D/G

6A

58

D/G

6B

Fukushima Dai-ichi Chronology - Power Loss

Extremely Confidential

Emergency DG: All 13 units were lost by Tsunami, except for one air cooling DG. The
seawater cooling DG were very vulnerable, especially its cooling devices, as located on
the seaside and flooded more.
Fukushima Dai-ichi： DG Systems
Sea water cooling emergency DG (10 units)
Unit 1A/B, Unit 2A, Unit 3 A/B, Unit 4A, Unit 5A/B, Unit 6A/H
Seawater pump
～～
Ocean
～～
Heat
海
exchanger～～～～
Air cooling DG (3 units)
Unit 2B, Unit 4B, Unit 6B

All functions lost
after tsunami

DG

Cooling water pump
Air cooler
DG

Air

Heat exchanger

If the cooling system for DG islost, the entire DG system would
be lost even though DG itself isactive.

Fukushima Dai-ni
Sea water cooling DG (12 units)
Units 1~4 A/B/H
Sea water pump
Ocean
～～

～

海
～～
～～

Heat
exchanger

Only Unit 6B
retained power

Cooling water pumpDG

3 units of Unit
3B/H, Unit 4H
retained power.

59

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Chronology - Power Loss

Extremely Confidential

Loss of power other than external power source: At Units 1-4 where the explosion
happened, the emergency DG, M/C electrical boards, and seawater cooling systems were
all lost. Only P/C boards in units 2&4, and DC power in unit 3 survived.
Loss of major power supply systems after tsunami
U n it 1
E l ect r ic al
p an el
ＤＧ１Ａ
E m e rg e n cy
ＤＧ

E m e r g en c y

U s ab i l E le ct ri c alit yp an el×

ＤＧ1Ｂ

F u k u sh im a D a i- ic h i
U n it 3
U n it 4

U n it 2

×

ＤＧ２Ａ

U s ab i l E le ct ri c alit yp an el×

ＤＧ２Ｂ（ A ir c o o lin g ）Ｄ Ｇ３Ａ

U s ab i l E le ct ri c alit yp an el×× （※ １） Ｄ Ｇ ３ Ｂ

×

Ｄ Ｇ４Ａ

U n it 5
U s ab i l E le ct ri c alit yp an el×

Ｄ Ｇ４Ｂ（ A ir c o o lin g ）Ｄ Ｇ ５ Ａ （※ ２ ）U n it 6
U s ab i l E le ct ri c alityp an el×× （※ １） Ｄ Ｇ ５ Ｂ（※ ２）×

Ｈ ＰＣ Ｓ

ＤＧ

Ｍ／ Ｃ

2Ｃ

×

Ｍ／Ｃ

３Ｃ

×

Ｍ／Ｃ

4Ｃ

×

Ｍ／Ｃ

5Ｃ

×

Ｍ／Ｃ

6Ｃ

○

Ｍ／Ｃ

１Ｄ

×

Ｍ／ Ｃ

2Ｄ

×

Ｍ／Ｃ

3Ｄ

×

Ｍ／Ｃ

4Ｄ

×

Ｍ／Ｃ

5Ｄ

×

Ｍ／Ｃ

6Ｄ

○

Ｍ／ Ｃ

２Ｅ

×

Ｍ／Ｃ

4Ｅ

×

Ｍ／Ｃ

１Ａ

×

Ｍ／ Ｃ

2Ａ

×

Ｍ／Ｃ

３Ａ

×

Ｍ／Ｃ

4Ａ

×

Ｍ／Ｃ

5Ａ

×

１Ｂ

×

Ｍ／ Ｃ
Ｍ／ Ｃ

Ｍ／Ｃ

１Ｓ

2Ｂ

×

Ｍ／Ｃ

２ SA

×

Ｍ／Ｃ

３Ｂ

×

Ｍ／Ｃ

4Ｂ

×

Ｍ／Ｃ

5Ｂ

×

×

M / C 5 S A -1

×

２ SB

×

M / C 5 S B -1

×

M / C 5 S B -2

×

H P C S D G M /C○

M / C 6 A -1

×

M / C 6 A -2

×

M / C 6 B -1

×

M / C 6 B -2

×

×

Ｍ／Ｃ

×

P /C ２ C○

P /C ３ C×

P /C 4 C-

P /C 5 C×

P /C 6 C○

P /C 1 D

×

P /C ２ D○

P /C ３ D×

P /C 4 D○

P /C 5 D×

P /C 6 D○

P /C ２ Ｅ

×

P /C 4 Ｅ

×

P /C 6 E○

P /C ２ Ａ○

P /C 4 Ａ-

P /C ２ Ａ - １

×P /C ２ Ｂ○

P /C 1 A

×P /C 1 B

×P /C 1 S×

Ｄ Ｃ １２ ５ Ｖ
ma i n& t r a ns f e r
bu s 1 Ａ
Ｄ Ｃ １２ ５ Ｖ
ma i n& t r a ns f e r
１ ２ ５ Ｖ Ｄ Ｃ bu s 1Ｂ

×

×

×

Ｄ Ｃ １２ ５ Ｖ
m a in & tr a ns fe r
bu s 2Ａ
Ｄ Ｃ １２ ５ Ｖ
m a in & tr a ns fe r
bu s 2Ｂ

×

×

３ SB

M / C 5 S A -2

P /C ３ Ａ××

P /C 6 Ａ - 1

×P /C 5 Ａ - 1○

P /C 6 Ａ - 2

×P /C 5 B

×

P /C 6 B - 1

×P /C 6 B - 2

×P /C 5 B - 1○

P /C ３ Ｓ Ａ

×P /C 5 S Ａ

×P /C 5 S Ａ - 1

×P /C ３ Ｓ Ｂ

×P /C 5 S B

×

○

○

○

×

×

Ｄ Ｃ １２ ５ Ｖ
m a in & tr a ns fe rb u s 3Ａ
Ｄ Ｃ １２ ５ Ｖ
m a in & tr a ns fe rb u s 3Ｂ

P /C 4 Ｂ

P /C 5 Ａ

P /C ３ Ｂ

Ｄ Ｃ １２ ５ Ｖ
m a in & tr a ns fe rb u s ４Ａ
Ｄ Ｃ １２ ５ Ｖ
m a in & tr a ns fe rb u s ４Ｂ

××

Ｄ Ｃ １２ ５ Ｖ
m a in & tr a ns fe rb u s 5Ａ
Ｄ Ｃ １２ ５ Ｖ
m a i n li neb o a rd 5 Ｂ○○

Ｄ Ｃ １２ ５ Ｖ
D I S T CE N T E R 6 Ａ

Ｄ Ｃ １２ ５ Ｖ
D I S T CE N T E R 6 B

○

○

A/B

Ａ

CCS A

×

ＲＨ ＲＳ

Ａ

×

Ｒ Ｈ ＲＳＡ×Ｒ Ｈ ＲＳＡ×Ｒ Ｈ ＲＳＡ×Ｒ Ｈ ＲＳ

Ａ

Ｂ

CCS B

×

ＲＨ ＲＳ

Ｂ

×

Ｒ Ｈ ＲＳＢ×

Ｒ Ｈ ＲＳＢ×

Ｒ Ｈ ＲＳＢ×

Ｒ Ｈ ＲＳＢ

H PC S D GSW: Lost functions: Unable to activate due to electrical board and/or cooling system were lost
: Incoming power was inaccessible due to the loss of electrical supply source● As to emergency DG, only one at unit 6
survived, and the rest were lost.

× （※ 2）

P /C 1 C

P /C ２ Ｓ Ｂ

S ea w at e r
sy st e m

３ SA

×
Ｍ／ Ｃ

DC
p o w er

○

×

Ｍ／Ｃ

N o rm al（ A ir c o o lin g ）１Ｃ

N o rm al

Ｐ／Ｃ× （※ 2）

Ｄ Ｇ６Ｂ

Ｍ／Ｃ

Ｍ／Ｃ

E m e r g en c y

Ｄ Ｇ６Ａ

U s ab i l it
y

×
×
×

● As to metal-clad switching gear (M/C), all
M/C were lost except for the one system atunit6.

● As to power center (P/C), all were lost in units
1 ~ 5.

● As to direct current (DC) batteries, all werelost by flooding at units 1, 2, and 4, making
functions of central control room and highpressure cooling lost as well.

● As to the seawater cooling systems, all were60
lost by tsunami.
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Chronology…

Extremely Confidential

The accidents in Units 1-3 had progressed in the following manner by the loss of power
supply and seawater cooling functions.
Event Progression (Conceptual)
Earthquake occurs

External event(M9.0. 4th largest in recorded history)

Countermeasures taken
Emergency shutdownof reactor (scram)

Loss of all external
power (AC)Problem occurred or progressed

Automatic activation of
emergency DGCore cooling by IC/RCICTsunami hit
Loss of all power(AC, DC, emergency DG)
Loss of water injection
Loss of ventilation (unit 1)

Temperature andpressure in PCV rise
Release gas from PCV(Manual vent)H2 leaks into

reactor bldg from PCV

Hydrogen explosion
at reactor bldg
( S/C pressure drops in unit 2)

Water level goes down.
Fuel rods start exposed.
Core de-pressurization(except for unit 1)

Core damage starts
with massive FP & H2
Water injection and coolingby fire truck, etc.

Fission products
released

61

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Overview

Extremely Confidential

Event developments at each plant from earthquake to the explosion are the following.
Damage to working environment

CommonEventsPlant response after earthquake Damage to plant● Emergency shut down (Scram succeeded)● Activated emergency generator (DG)
● Activated high pressure cooling

3/11

Earthquake (14:46)

Tried to connect a power supply vehicle toNo.2 (P/C was active) to secure power.

Tried to recover reactor No.1 at first.

Fukushima Dai-ichi No.1

3/12

● Loss of entire power● Loss of seawater cooling● IC was functioning?
● Assigned 1 fire truck

Core damage
started(approx. 18:46. estimated)

Dai-ichi No.2

Put lower priority on No.4 as it wasunder regular inspection & on halt.

● Loss of entire AC power● Loss of seawater cooling● DC battery available● RCIC available● HPCI available

Dai-ichi No.3

Dai-ichi No.4

● Loss of entire power● Loss of seawatercooling system● Regular/ emergency
P/C available

Cooling by RCIC(15:05)

Massive generation& accumulation of hydrogen

Hydrogen Explosion (15:36)
3/13

3/15

Tried to keep RCIC in No.3 (battery
was active) to buy more time.

● Loss of entire power● Loss of seawater cooling● Regular/emergency P/Cavailable● RCIC available● Assigned 1 power supply
Cooling by RCIC(14:50) vehicle

・ Water injection by fire truck(x 80. 5:46~14:53)

3/14

Loss of all external power (14:46)
Loss of entire Emergency DG (15:37)
DC batteries flooded (~15:41)
Loss of seawater cooling system

Severe damage to plant and site
(simultaneously to No.1 – 4)

Tsunami hit (15:35)

・ Tried to reduce core pressure.
・ Couldn’t monitor water level
reaching to TAF. Couldn’t feedwater. Water level went down・ Core boiled w/ no water in it

●
●
●
●

● Darkness (No lighting)● No monitoring data (loss of measurement and control function)● Fire trucks: 1 out of 3 = damaged by Tsunami (15:37),1 = isolated at No.5&6
and unable to transport (15:37)● No communication means, difficult to instruct and direct (bwn central control
room & fields)● Difficult to transport people & materials (liquefaction & rubble)● Horribly severe working environment (frequent aftershocks, high radiation)● Limited activity & working hours (lack of protective suits, masks &dosimeters)

RCIC stopped (11:36)
Power supply vehicle
damaged (approx.15:36)

Cooling by HPCI(12:35)

Trying to connect the vehicle to
P/C to recover AC.
Vehicle destroyed by explosion.

Was preparing water injection by
fire truck as battery for RCIC was
running out.
17:17 Water level = TAF (estimated).
Around 18:00 Started to reduce core pressure.
Core boiled with no water in it.

HPCI stopped (2:42. DC depleted)Core damage started(approx.8:46. estimated)

4:15 Water level = TAF.
Core boiled with no water in it.

Hydrogenaccumulation
Massive generation(back flow from No.3
& accumulation of hydrogen
9:08 Rapid depressurization of the core since its core damage?)
9:25 Started water injection by fire truck(Pure water with boric acid)

Fire truck damaged (apx.11:01)

Hydrogen Explosion (11:01)
RCIC stopped (approx.13:25)
Core Damage Started(approx. 19:46. estimated)
Massive generation& accumulation of hydrogen

After RCIC stopped, tried & failed vent(both W/W & D/W) as R/D didn’t rupture (=high designed pressure).

Hydrogen discharged from blowout panel?
(PCV damaged?) S/C pressure = 0 MPa(abs)

Hydrogen Explosion (6：12)

62
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Chronology…

Overview of standard operating procedure in case of Station Black Out (SBO)
Loss ofall AC power

Status of safety measures at this time
Fukushima Dai-ichi(1) Core cooling by highpressure water injection••

Had maintained high-temperature stand-by by high pressure cooling systems such as Isolation Condenser(IC), Reactor Core Isolation Cooling (RCIC, @ unit 2&3), High Pressure Coolant Injection (HPCI).
As DC batteries are assumed to last for 8~10 hours in case of SBO (= loss of high pressure injection), it
is necessary to recover emergency DG or external power and prepare for low pressure coolant injectionin the mean time.

Unit 1

Unit 2

Unit 3

Units 1-4

×

○

○

○

△

△

○

(2) Depressurization of reactor pressure vessel (RPV)×• Once low pressure coolant injection is ready, depressurize RPV by manually open
Safety Relief Valve.

Dai-ni(Delayed) (Delayed)(3) Water injection to core by low pressure water injection (including alternatives)△(Delayed orlack of water)• If emergency DG or external power restored, inject water by Make Up Water System orCore Spray System.
• If not, inject water by Diesel Driven Fire Pump (D/D FP).
• If D/D FP lost, inject water by fire trucks.

(4) PCV cooling (&power) available?

Y(5) Heat removal （&power & ultimate heatsink） available?

Y
Cold shutdownN(6) Heat removal of PCV (primary containment vessel) by vent• If core not damaged, use wet-well (W/W) vent at the highest usable
pressure (Pd) of PCV to protect PCV. Use dry-well vent if W/W vent* lost.
• If core damaged, massive radioactive materials are in the PCV. Secure
time and use W/W vent at Pd ~ 2Pd to mitigate the release of radioactive
materials to the open air.
*: W/W vent mitigates the release of radioactive materials to theenvironment through its water filter.

△(Vent
delayed)

×

○

△

○

(Difficult tokeep ventvalves open)(PCV coolingavailable)○ : Succeeded△ : Conducted but troubled
63
× : Failed

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 1… Chronology

Extremely Confidential

Power, coolant, & ventilation functions were all lost due to Tsunami, not earthquake. Water injected in 15 hrs after the earthquake, ventilation in 24 hrs.
Events

3/11 14:46
Emergency
shutdown of thereactorImplications

Earthquake occurred (level 6+)(M9.0. 4th in recorded history)● 14：46 Automatic shutdown of the reactor => 14：52 IC activatedautomatically & opened/ closed manually.
● Loss of all external power => 14：47 Emergency DG activated.
15:35
Tsunami hit●
・All external AC power was lost due to the earthquake.
The reactor reacted (scrammed) to earthquake in accordance with the design. No major problems found.

●・All of AC/DC power was lost due to huge submersion and destruction by Tsunami
Tsunami submerged and destroyed buildings, tanks, seaside facilities. Debris was strewn all over theinside of buildings and roads, and obstructed recovery work, transportation of staff &supplies (=> work
environment degraded).
Power boards were submerged by Tsunami. Major command functions (lights, measurement,
communications) were all lost (=> Core water level, pressure, & temperature could not be measured).
Emergency DG*2 & electrical panels flooded by tsunami. All AC power lost. (=> could not use
electricity)
Seawater pumps on the seaside were flooded and disabled by Tsunami. Along with all AC power
outage, residual heat removal system (water pump, pump cooling device) was lost (=> could not cool
the core)(*2: In Units 5 & 6 (ground height = 13m), 1 emergency DG survived and cold-shutdown achieved.
However, units 1-4 (ground height = 10m) lost all of their emergency DG.

(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

Loss ofall power&
importantfunctions

Secureemergency
power.
Prepare forcoolant
injection.

・
Simultaneous loss of all power, cooling, & pressure-control functions +darkness & terrible work environment.
・● Emergency DG & power panels flooded => all AC power lost => Unable
to use electrical equipments.
● Battery room submerged => DC power lost => Electrical boards,
measuring & control facilities lost => Cooling function lost (IC, HPCI),
Pressure control function lost (open SRV remotely etc.)● Seawater pump lost => Function for cold-shutdown lost (ultimate heatsink lost)

Right after tsunami: Isolation Condenser lost=> Core water level started to drop.

18：46 Core damage started (estimated)*0:

Instrument forwater level may
not have beenreliable.

Hydrogenbuilt up.

With all AC/DC power lost, all functions of core cooling & ventilation were lost.
Water injection systems to the core & spent fuel pool were lost (=> could not cool the core)
The electromagnetic / motor-driven valve for AO valve did not function properly. (=> could not control
the pressure & heat of RPV & PCV)●・

Manual for disaster management did not predict simultaneous loss of functions.
Manual (AM) had assumed SBO (loss of all AC power), but not the simultaneous loss of all AC/DC
power & cooling functions.
Countermeasure, preparation, and training for the simultaneous loss of power, cooling,& vent function
were insufficientEquipments on site, and dosimeters, masks, & protective gear were lacked.

09：04 Workers departed for site for ventilation.
10：17 Started PCV vent.
14：30 PCV vent succeeded (D/W pressure decreased)
14：53 Completed freshwater injection (80,000 l in total).
14：54 Plant manager ordered sea water injection.

15:36
Reactor building exploded (5th floor)
Hydrogen
19：04 Started sea water injection.
Explosion &radiation leak 20:45 Started sea water injection with boric acid.

・・●

02：30 Confirmed ‘RPV pressure is low & PCV pressure is high’*1.
05：46 Started to inject fresh water by fire trucks.
*1: Estimated that the
07：20 RPV damaged. (simulation)

Triedventilation.

●
・・

17：12 Plant manager ordered to consider water injection by fire pump system & fire truck

21：19 Core water level became readable (TAF + 200mm*0)
23：00 Rise in radiation level in turbine bldg confirmed.
Prepare forAround then, 1st power supply vehicle arrived.
ventilation
00：06
Plant
manager ordered to prepare vent.
3/12(as Dry-well of PCV pressure possibly over 600k Pa)
01：30 Requested to execute vent & approved by the country.

Tried water
injection.

・

core temperaturerose due to coredamage, andhydrogen leaked
from SRV flange
gasket etc.

・
・
・
・
・
●
・
・
・

Combined all of the above together at one time, they could not monitor the plant &recovery actions were delayed even after the core damage started.
Could not monitor the core water level. (data was read in 6.5 hours after earthquake).
Delay in securing alternative power (in 8 hours after earthquake).
Delay in water injection to the core (same, 15 hours later).
Delay in vent operation to release heat/pressure from highly pressurized PCV (same, 24 hours later).
Lack of monitoring hydrogen buildup in the building, and countermeasure action (led to explosion).
As a result, the hydrogen accumulated in 5th floor of reactor building & exploded.
Cladding tube of fuel rods (zirconium) reacted with water & massive hydrogen was generated.
PCV de-pressurization & cooling delayed. The hydrogen leaked from PCV into the reactor building.
During recovery work, being unable to detect hydrogen nor comprehend the situation, large
64quantities ofhydrogen accumulated on the 5th floor and exploded.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 2… Chronology

Extremely Confidential

Chronology of Unit 2
Events

3/11 14:46
Emergency
shutdownof thereactorEarthquake occurred (Level 6+)(M9.0. 4th in recorded history）● 14：47 Automatic shutdown of the reactor.
● Loss of all external power => Emergency DG automatically activated.
14:50 RCIC activated manually => 14:52 Stopped automatically (high water level = L-8).
● 15:01 Sub-criticality of the core confirmed

Tsunami hit
15:35
Loss ofall power&
seawatercoolingfunctions

Secure highpressure
cooling.

2:55
17:30

3/13

11:00

Prepare forlow pressure 3/14
coolant
injection.

11:01

Prepare forventilation

13:25
17:17

●
・

All external power was lost due to earthquake
The reactor reacted (scrammed) to earthquake in accordance with the design. No major problems
found.

●All power (DC/AC) was lost due to large scale submersion and destruction causedby tsunami
Could not share the power with other plants due to Tsunami. As debris was strewn all overbuildings and road, could not access to the active electrical panel (P/C). This delayed restorationof power.

・(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

15:39 RCIC activated manually.
●
15:41 All AC power lost (emergency DG & electrical panel immersed) =>Extreme work environment, darkness.
Battery room submerged & All DC power lost (some P/C not submerged). => RCIC
continued. Seawater systems submerged & ultimate heat sink lost. =>Function for cold shutdown lost.
17:12 Plant manager ordered to consider water injection by fire truck.
22:00 Core water level became readable (TAF +3400mm)
3/12

Implications

Confirmed RCIC was in operation.
(As RCIC confirmed as working, prioritized ventilation of Unit 1 at first.)
Plant manager ordered to prepare for PCV vent.
S/C vent valve (large) opened &vent-line structured.
(As D/W pressure was low, rupture disk did not rupture & ventilation failed).
Unit 3 exploded & excitation circuit for electro-magnetic valve damaged. S/C vent valve(large) closed and unable to open again. Also, explosion destroyed the fire truck andmakeshift hoses & water injection lines were unusable.
Reduction trend of reactor’s water level confirmed. => Judged as RCIC not working.
Reactor’s water level reached at TAF.

17:17~ Core damage started (estimated)

●
・

・

・

・
・

●
・
・
・

Core depressurized.
LP coolant
injection.
Tried & failed
ventilation.
Core damage &hydrogen built
up.
3/15

18:00
18:22
19:54
21:00
22:50
23:35

0:02
6:00~
PCV damaged.
6:10
Radiation leak.

Started core de-pressurization (core pressure = 5.4MPa => 19:03 0.63MPa)
Water level reached at TAF -3700mm. Judged as core was exposed. => Reported to
METI.
Started sea water injection to the core with fire pump system & fire trucks.
S/C vent valve (small) slightly opened & reconstruction of vent line completed.
While D/W pressure exceeds maximum usage pressure 427kPa (& kept rising), S/C
pressure stayed at 300~400 kPa gage, and both pressures (DW & S/C) did not converge.
As rupture disk of S/C did not rupture (insufficient pressure), they decided to vent via
D/W by opening small valve.
Opened D/W vent valve (small) & vent line structured. (but, the valve closed again a few
minutes later). (D/W pressure did not drop below 750kPa (abs) & stayed at high level.)

●
・
・
・

●
・

‘Core cooling’ & ‘vent’ functions were lost due to loss of all power.
Although they had once connected the fire truck to active P/C in order to inject water by CRD &SLC, which were not submerged, the explosion at Unit 1 destroyed the power supply vehicle andcables which became unusable.
While RCIC working, they were setting up seawater injection lines with fire truck in case for runout of RCIC. However, the explosion at Unit 3 destroyed the fire trucks and water injection hoses
which became unusable. After that, RCIC stopped & water level started to drop.
Reconstruction of seawater injection line was delayed due to frequent aftershocks, and was only
completed 3 hrs after RCIC stopped. Furthermore, as fuel for fire trucks ran out, water injection
started only 6 hours later & the core was depressurized for about 1 hour.
As air compressor not available, they used car batteries to open Safety Relief Valve from thecentral control room. It took close to 2 hours due to insufficient voltage.
While D/W pressure rose, S/C pressure remained at a level insufficient to activate rupture disk.
This delayed and obstructed the vent operation either.
Manual for disaster management did not predict simultaneous loss of functions.
Manual (AM) had assumed SBO (loss of all AC power), but not the simultaneous loss of all
AC/DC power & cooling functions.
Countermeasure, preparation, and training for the simultaneous loss of power, cooling,& ventfunction were insufficientEquipments on site, and dosimeters, masks, & protective gear were lacked.
Combined all of the above together at one time, they could not monitor the plant &recovery actions were delayed even after the core damage started.
Could not monitor the core water level. (data was read in 7 hours after earthquake).
Delay & failure of D/W & S/C vent operation (if PCV were damaged.)
Lack of monitoring hydrogen buildup in the building, and countermeasure action (if hydrogen
explosion occurred).
As a result, PCV was damaged
Due to high temperatures/ pressure in PCV, the vessel was damaged near S/C (assumed).

65

S/C pressure indicated at 0kPa(abs)
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 3… Chronology

Extremely Confidential

Chronology of Unit 3
EventsEmergency
shutdownof thereactor3/11 14:46

Earthquake occurred (Level 6+)(M9.0. 4th in recorded history）● 14：47 Automatic shutdown of the reactor. => 15:05 RCIC activated manually =>15:25 RCIC tripped (high water level).
● Loss of all external power => 14:48 Emergency DG automatically activated.
15:35

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

Loss of all AC power + darkness & terrible work environment.

Loss ofall power&
seawatercoolingfunctions● Emergency DG & power panels flooded => 15:38 all AC power lost => Unable to use
electrical equipments.
● Seawater pump destroyed => Function for cold-shutdown lost. (ultimate heat sinklost)
● DC main lines survived. (Kept supplying DC power by backup batteries to RCIC, HPCI,
measurement instruments).

Implications●
・All external AC power was lost due to the earthquake.
The reactor reacted (scrammed) to earthquake in accordance with the design. No major
problems found.

●・Though All AC power was lost by Tsunami, DC survived.
Tsunami submerged and destroyed buildings, tanks, seaside facilities. Debris was strewn allover the inside of buildings and roads, and obstructed recovery work, transportation of staff&supplies (=> work environment degraded).
Emergency DG*2 & electrical panels flooded by tsunami. All AC power lost. (=> could notuse electricity)
Seawater pumps on the seaside were flooded and disabled by Tsunami. Along with all AC
power outage, residual heat removal system (water pump, pump cooling device) was lost (=>could not cool the core)
Although the power board in the building was submerged by Tsunami, DC 125V escaped
immersion. It powered RCIC, HPCI, lights in the central control room, and measurement
instruments of core water level & pressure.
(*2: In Units 5 & 6 (ground height = 13m), 1 emergency DG survived and cold-shutdown
achieved. However, units 1-4 (ground height = 10m) lost all of their emergency DG.

・・・

16:03 Core cooling by RCIC (manually activated)

DC survived
then run out.

3/12

11:36 RCIC stopped (fire trucks used for Unit 1).
12:35 High pressure water injection (HPCI) automatically activated (water level = low).
17:30 Plant manager ordered to prepare for PCV vent.

3/13

02:42
03:51
04:15
05:10
05:15
08:41

RCIC/HPCI
worked thenlost.
Prepare forventilation

HPCI stopped (battery depleted).
Water level indicated as 1600mm below the fuel top (= TAF -1600mm).
Judged the water level reached at TAF.
Judged that RCIC failed to inject coolant.
Plant manager ordered to construct vent line systems.
Vent line excluding RD had been set up.

08：00 ~ 09：00 Core damage started (estimated)

LP coolant
injection.
Conducted
PCV
ventilation.
Core damage& hydrogen
3/14
built up.

09:08
09:25
09:36
10:30
11:17
12:20

Core de-pressurized by SRV (used car batteries of workers).
Started fresh water injection by fire trucks (with boric acid).
Confirmed D/W pressure dropped after vent operation.
Plant manager ordered to prepare sea water injection.
AO valve of S/C vent closed (pressure of air compressor lowered).
Fresh water injection completed (since fresh water in fire protection water tankdepleted).
12:30 AO valve of S/C vent opened (air compressor changed).
13:12 Started sea water injection by fire trucks (frequent aftershocks delayed
its preparation).

01:10
03:20
05:20
09:20
10:53

Seawater injection by fire trucks stopped for replenishing, due to lack of sea water.
Seawater injection resumed.
S/C vent AO valve opened. 06:10 Confirmed the AO valve opened.
Started to supply seawater from the wharf to reverse-valve pit. (retarded by highradiation level & bad transportation)
7 water supply vehicles (5t) brought in by Self-Defense Force. Placed them toreverse valve pit & re-started fresh water injection.

●
・
・
・
●
・
・
・
●
・
・
・
・

With all AC power lost & batteries run out, all the core cooling function was lost.
Water injection systems to the core & spent fuel pool were lost (=> could not cool the core)
As core pressure rose when RCIC & HPCI stopped, they used Safety Relief Valve to decreasepressure. (Decay heat could not be removed although the water was injected).
As HPCI & RCIC stopped with the batteries depleted, core water level was not regained.
Manual for disaster management did not predict simultaneous loss of functions.
Manual (AM) had assumed SBO (loss of all AC power), but not the simultaneous loss of all
AC/DC power & cooling functions.
Countermeasure, preparation, and training for the simultaneous loss of power, cooling,& ventfunction were insufficientEquipments on site, and dosimeters, masks, & protective gear were lacked.
Combined all of the above together at one time, they could not monitor the plant& recovery actions were delayed even after the core damage started.
Delay in recovery actions due to frequent aftershocks.
Delay in water injection to the core due to lack of fire trucks.
Vent preparation & operation were relatively smooth? (executed in 4 hours since ordered).
Lack of monitoring hydrogen buildup in the building, and countermeasure action (led to
explosion).

66
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 3… Chronology

Chronology of Unit 3 (continued)
EventsHydrogen
Explosion &radiation leak

3/15

11:01

Reactor building exploded (4th& 5th floor)
Fire truck and hoses were destroyed & seawater injection suspended.

16:30 Injection line from the wharf to the core was constructed. Sea water
injection resumed.

Implications●

As a result, the hydrogen accumulated in 5th floor of reactor building &exploded.

・・・

Cladding tube of fuel rods (zirconium) reacted with water & massive hydrogen was generated.
PCV de-pressurization & cooling delayed. The hydrogen leaked from PCV into the reactor building.
During recovery work, being unable to detect hydrogen nor comprehend the situation, large
quantities of hydrogen accumulated on the 5th floor and exploded.

07:55 Floating of moisture above the building confirmed.

67
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 4… Chronology

Chronology of Unit 4
Implications

Events
3/11 14:46
Emergency
shutdownof thereactorEarthquake occurred (Level 6+)(M9.0. 4th in recorded history）● Under regular inspection from November 30th, 2009, (reactor was on halt). = 1535
rods of spent fuel stored in SFP(97% full).
● Loss of all external power => 14:47 Emergency DG automatically activated.
● Water sloshed & spilled over from the pool & water level dropped (approx. 0.5m)
15:35

Loss of all AC power + darkness & terrible work environment.
● Emergency DG & power panels flooded => all AC power lost => Unable touse electrical equipments.
● Battery room submerged => DC power lost => Electrical board, measurement/
controlling facilities malfunctioned. => Cooling function lost (RHR).
● Seawater pump for Fuel Pool Cooling & Filtering (FPC) system damaged. =>Cooling function lost (ultimate heat sink lost).

Water level ofSFP
monitored.

As the pool temperature continued to rise by the decay heat ofused fuel, water level in the pool decreased with its water
evaporated.

Prepare to
maintainwater level.

● The water level was estimated to reach to the top of fuel rods around March
20th.
● Since the pool gate was closed before earthquake, the water level was thesame as the one at the well side of DS pit. So, it was reasonably expected thatthe pool gate would open to supply water to SFP from the well side if thewater level in SFP continue to drop.

Hydrogenflowed backfrom Unit 3.

3/14

04:08 SFP temperature was confirmed as 84 ℃.
11:01 Unit 3 explosion

Hydrogen
3/15 06：12
Explosion &radiation leakAll external power was lost due to earthquake
Although one emergency DG started automatically due to the loss of external power, there
was no other power source. Drop of water level by sloshing & spillover was predicted.

●

All AC power was lost due to large scale submersion and destruction causedby tsunami.
Tsunami submerged and destroyed buildings, tanks, seaside facilities. Debris was strewn
all over the inside of buildings and roads, and obstructed recovery work, transportation ofstaff &supplies (=> work environment degraded).
Emergency DG & electrical panels flooded by tsunami. All AC power lost. (=> could notuse electricity)
Seawater pumps on the seaside were flooded and disabled by Tsunami. Along with all AC
power outage, cooling function for SFP was lost (=> SFP water level drops by
evaporation).
Spent fuel could be damaged if water level continued to drop. But after evaluation, they
predicted that the water level would reach at the top of spent fuel on March 20th, (so thatthey could spend more of their time on other units.)
They actually measured the water temperature & confirmed it had not reached boilingpoint (84℃).

・Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

Loss ofall power&
seawatercoolingfunctions●・

Huge detonation sound.
Reactor building severely damaged (4th & 5th floor)

・
・

・

・

●
・
・

●
・
・
・
・

● Pool gate opened due to explosion, and water level recovered up to well level (estimated).
Fire brokeout &extinguished.

water
injection
started.

3/16 09:38 Fire broke out from the 3rd floor of the reactor building.
11:00 Fire extinguished naturally.
Water level confirmed from helicopter (4-5m above the fuel top)
3/20 08:21 Started to spray water to the SFP (continued periodically).

●・

Manual for disaster management did not predict simultaneous loss offunctions.
Manual (AM) had assumed SBO (loss of all AC power), but not the simultaneous loss of
all AC/DC power & cooling functions.
Countermeasure, preparation, and training for the simultaneous loss of power, cooling,&
vent function were insufficient
Nuclear reactor building exploded/damaged.
The explosion was not expected, and the cause was not clarified. TEPCO assumed that thehydrogen flowed back from Unit 3 into Unit 4, and exploded.
Pool gate opened by explosion. Water flowed into the pool from well side. Water level
was recovered (assumed).
Afterward, a fire broke out & was extinguished naturally. Its cause is unknown (could be
the hydrogen combustion).
Lack of monitoring hydrogen buildup in the building, and countermeasure action (led to
explosion).
Water injection to used fuel pool
The actual water level was higher than originally assumed. The water injection to the spent
fuel pool was begun on March 20th.

68
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 5… Chronology

Chronology of Unit 5 (Before earthquake, it had been on halt for regular inspection (pressure 7MPa, water temperature 90℃). Fuel rods were loaded in the core)
Implications

EventsEmergency
shutdownof thereactor3/11 14:46

Earthquake occurred (Level 6+)(M9.0. 4th in recorded history）● All external power lost. => 14:47 Emergency DG automatically started.
15:35

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)● Emergency DG stopped => 15:40 All AC power lost => Unable to use
electrical equipments.
● Seawater pump lost => Function for cold shutdown lost (ultimate
heat sink lost).
● DC main line escaped submergence (DC power supplied by backup
batteries).

Loss ofall power&
seawatercoolingfunctions

3/12

Supplied
AC powerfrom Unit 6.
Water
injection toreactorand SFP.

3/13

3/14

SRV automatically opened (core pressure 8MPa maintained).
Core depressurized with opened the valve at top of RPV.
Started receiving power from emergency DG at Unit 6 via regular cable(DC power maintained).
14:42 Air conditioning system activated manually & air cleaning in central
control rooms for units 5&6 resumed.
18:29 Started to supply power to MUWC system from Unit 6’s DG via
makeshift cables.
20:54 MUWC pump manually activated.
21:01 Stand-by Gas Treatment System (SGTS) manually activated.
5:00
5:30
9:27

Core depressurization by opening SRV (continued hereafter).
Started water injection to the core by MUWC (continued hereafter).
Water supply to SFP begun (continued hereafter).

3/18

13:30 Holes opened at the roof of reactor building (3 places).

3/19

1:55

Emergency
pump
recovered.
Cold
shutdown
achieved.

1:40
6:06
8:13

4:22
5:00
3/20

Makeshift seawater pump for RHR activated by makeshift power frompower supply vehicles.
2nd emergency DG activated at unit 6.
RHR pump started manually(Started cooling SFP in emergency heat-load mode).

10:49 RHR stopped manually
12:25 RHR started manually (started core cooling by shut-down coolingsystem).

14:30 Cold shutdown achieved.

●
・
・
●
・
・

・

・
●
・

●
・

・

・

All external power was lost due to earthquake.
Just before the earthquake, fuel rods were loaded, and the leakage test of RPV wasundergoing (Reactor pressure 7Mpa, water temperature 90℃ (core), 25℃ (SFP).
Emergency DG activated in accordance to design.
AC power at Unit 5 was all lost due to submergence by tsunami &supplied from DG at Unit 6.
2 emergency DG lost due to tsunami. In the early morning of March 12, regular cable
was connected between Units 5&6, and DC power supplied from DG at Unit 6.
With DC power secured, they could monitor parameters in the central control room
for recovery actions and countermeasures. Also, by activating emergency ventilation& air conditioning system at Unit 6, work environment in central control rooms ofUnits 5&6 was improved. (Full masks unnecessary.)
As all sea water pump system as well as high-voltage power boards were submerged
and lost, they structured makeshift cables from Unit 6 to 5, and supplied AC power toequipments for recovery operations at Unit 5.
With SGTS activated, they maintained negative pressure in the reactor building.
Core depressurization succeeded. Started water injection to reactor andspent fuel pool with makeshift power.
After earthquake, core pressure first went up by decay heat, then stayed around
8MPa & SRV was automatically opened. They opened the apex valve of RPV to
reduce core pressure, which was eventually decreased to atmospheric pressure. Also,
through lines for AM, they started to inject water to the nuclear reactor and SFP.
Makeshift power recovered & cold shutdown achieved.
As water levels of the reactor & SFP were maintained since earthquake, it was very
unlikely that hydrogen was being produced. But just in case, they opened 3 passage
openings (3.5cmφ~7cmφ) in the roof of reactor building by boring machines.
Regarding RHR, since seawater pumps were lost, they carried in makeshift generator& seawater pump, and connected a makeshift cable from Unit 6 in order to construct
RHR system line. With RHR pump activated, they cooled the reactor & SFP
alternately.
After water temperature of SFP dropped, cold shutdown of the core had beenachieved.

69
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 6… Chronology

Extremely Confidential

Chronology of Unit 6 (Before earthquake, it had been on halt for regular inspection. Fuel rods were loaded in the core)
Events
3/11 14:46
Emergency
shutdownof thereactorImplications

Earthquake occurred (Level 6+)(M9.0. 4th in recorded history）●
・● All external power lost. => 14:47 Emergency DG automatically started.
15:35

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

Loss ofall power&
seawatercoolingfunctions● 15:36 2 Emergency DG stopped => 1 DG was sound & AC power secured.
● Seawater pump lost => Function for cold shutdown lost (ultimate
heat sink lost).
● DC main line escaped submergence (DC power supplied by backup
batteries).

・
●
・
・

3/12

Maintainedwater levelof core &
SFP.
3/13

6:03 Started to construct power supply line from emergency DG.
8:13 Supplied power from emergency DG to Unit 5 via main cable.
14:42 Activated air conditioning system manually, and started air
cleaning for central control rooms of both Units 5&6.
13:01 Activated MUWP manually. => Started water supply to the core.

3/14

14:13 Started water supply to SFP (continued periodically hereafter).

3/16

13:10 Activated Fuel Pool Cooling & Filtering system manually.
(without heat removal function. only circulation).

3/18

17:00 Opened passage in the roof of reactor building (3 spots).
19:07 Activated seawater pump for emergency DG.

Emergency
3/19
pump
recovered.
Cold
shutdown
achieved.

3/20

4:22 Activated 2 emergency DG.
21:26 Activated makeshift seawater pump for RHR (with makeshift
power from supply vehicle).
22:14 Activated RHR manually. (Started cooling SFP in emergency heatloaded mode).

・・All external power was lost due to earthquake
Just before the earthquake, fuel rods were loaded, and the reactor was in the mode of cold
shutdown.
Emergency DG activated in accordance to design.
Emergency DG survived & power was secured. However, seawater cooling
function was lost.
Though 2 emergency DG were lost due to tsunami, one air-cooling DG & emergency
power boards survived. Therefore, power source was secured.
With DG power secured, they could monitor parameters in the central control room forrecovery actions and countermeasures for the reactor & SFP. Also, by activating
emergency ventilation & air conditioning system, work environment in the central control
room was improved. (Full masks unnecessary.)
All sea water pump system were submerged and lost.
With SGTS activated, they maintained negative pressure in the reactor building.

●・

Maintained water level by injecting water to the core & SFP.
They activated Make Up Water Pump system by emergency DG, and injected water tothe core & spent fuel pool. After that, they activated Fuel Pool Cooling & Filteringsystem to circulate the pool water in order to mitigate the rise in water temperature.

●・

Makeshift power recovered & cold shutdown achieved.
As water levels of the reactor & SFP were maintained since earthquake, it was very
unlikely that hydrogen was being produced. But just in case, they opened 3 passage
openings (3.5cmφ~7cmφ) in the roof of reactor building by boring machines.
Regarding RHR, they restored seawater pump system with makeshift generator &seawater pump. With RHR pump activated, they cooled the reactor & SFP alternately.
After water temperature of SFP dropped, cold shutdown of the core had been achieved.

・・

16:26 Stopped RHR manually (emergency heat loaded mode).
18:48 Activated RHR manually (started core cooling with shutdown
cooling system).

19:27 Cold shutdown achieved.

70
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 1… Chronology… Progression of Accident

Progression of the accident: The hydrogen was generated by water-zircaloy reaction,
accumulated and exploded in 5th floor, leading to the leakage of radioactive material.
3/11 14:46

Emergency
shutdown of thereactor

EventsEarthquake occurred (level 6+)

Progression of accident (conceptual)(M9.0. 4th in recorded history)

Earthquake occurs● 14：46 Automatic shutdown of the reactor => 14：52 IC activatedautomatically & opened/ closed manually.
● Loss of all external power => 14：47 Emergency DG activated.
15:35
Tsunami hit(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

External event
Countermeasures taken
Problem occurred orprogressed

Loss of all external
power (AC)(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)
Loss ofall power&
importantfunctions

Automatic activation of
emergency DG● Emergency DG & power panels flooded => all AC power lost => Unable
to use electrical equipments.
● Battery room submerged => DC power lost => Electrical boards,
measuring & control facilities lost => Cooling function lost (IC, HPCI),
Pressure control function lost (open SRV remotely etc.)● Seawater pump lost => Function for cold-shutdown lost (ultimate heatsink lost)

Right after tsunami: Isolation Condenser lost=> Core water level started to drop.

Secureemergency
power.

Core cooling by IC
Tsunami hit
Loss of all power(AC, DC, emergency DG)

17：12 Plant manager ordered to consider water injection by fire pump system & fire truck

Prepare forcoolant
injection.

18：46 Core damage started (estimated)

21：19 Core water level became readable (TAF + 200mm*0)
23：00 Rise in radiation level in turbine bldg confirmed.
Around then, 1st power supply vehicle arrived.
3/12 00：06 Plant manager ordered to prepare vent.
(as Dry-well of PCV pressure possibly over 600k Pa)
01：30 Requested to execute vent & approved by the country.

Prepare forventilation

02：30 Confirmed ‘RPV pressure is low & PCV pressure is high’*1.
05：46 Started to inject fresh water by fire trucks.
07：20 RPV damaged. (simulation)
Tried water
injection.
Triedventilation.
Hydrogenbuilt up.

Hydrogen
Explosion &radiation leak

09：04 Workers departed for site for ventilation.
10：17 Started PCV vent.
14：30 PCV vent succeeded (D/W pressure decreased)

Loss of water injection
Loss of ventilation

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

Release gas from PCV(Manual vent)Core damage starts
with massive FP & H2

H2 leaks into

14：53 Completed freshwater injection (80,000 l in total).
14：54 Plant manager ordered sea water injection.

reactor bldg from PCV

Water injection and coolingby fire truck, etc.

Reactor building exploded (5th floor)

Hydrogen explosion
at reactor bldg

Fission products
released

15:36

19：04 Started sea water injection.
20:45 Started sea water injection with boric acid.

71

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 1… Deduced Problems…

Problems deduced from the events: Simultaneous loss of all power and cooling & vent functions had
disabled the recovery operations, and taken the ‘cool and shut-down the core’ function away.

Emergency
shutdownof thereactor

Progression of accident (conceptual)

Problems

Earthquake occurs

AC power was lost over the long-term due to earthquake and tsunami.
AC power was lost over the long-term due to earthquake and tsunami.
● As Unit 2 also lost power, the power could not be shared with Unit 1.
● As Unit 2 also lost power, the power could not be shared with Unit 1.
● Due to submergence, there was no electrical panel to be connected with the power supply vehicle.
● Due to submergence, there was no electrical panel to be connected with the power supply vehicle.
● Due to extremely bad environment, even after the power supply vehicles arrived, reaching power● Due to extremely bad environment, even after the power supply vehicles arrived, reaching power
connection port, and connection itself was difficult.
connection port, and connection itself was difficult.

(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

Loss of all external
power (AC)Automatic activation of
emergency DG

Loss ofall power&
importantfunctionsCore cooling by IC
Tsunami hit

Secureemergency
power.
Prepare forcoolant
injection.
Prepare forventilation

Loss of all power(AC, DC, emergency DG)
Loss of water injection
Loss of ventilation

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

Release gas from PCV(Manual vent)Core damage starts
with massive FP & H2

Tried water
injection.
Triedventilation.
Hydrogenbuilt up.

Hydrogen
Explosion &radiation leak

H2 leaks into

reactor bldg from PCV

Hydrogen explosion
at reactor bldg

Water injection and coolingby fire truck, etc.

Fission products
released

AM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longAM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longterm).
term).
● As IC is DC driven, along with DC loss, MSIV was closed (unable to access to internal valves for vent).
● As IC is DC driven, along with DC loss, MSIV was closed (unable to access to internal valves for vent).
● Due to all power loss, they could not remotely open the valves for ventilation.
● Due to all power loss, they could not remotely open the valves for ventilation.
● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure
handbook for SBO only assumed that DC power was normal).
handbook for SBO only assumed that DC power was normal).
Securing alternative cooling water source was insufficient and delayed.
Securing alternative cooling water source was insufficient and delayed.
● Due to power loss, core depressurization was delayed (battery depletion, insufficient pressure of air compressor).
● Due to power loss, core depressurization was delayed (battery depletion, insufficient pressure of air compressor).
● Lack of easy depressurization method under DC loss. Not prepared for working under high radiation● Lack of easy depressurization method under DC loss. Not prepared for working under high radiation(alternative method other than SRV necessary?).
(alternative method other than SRV necessary?).
● There was a malfunction in diesel-driven fire extinguishing pump.
● There was a malfunction in diesel-driven fire extinguishing pump.
● Liquefaction & debris caused extreme difficulty in accessing & constructing external water injection● Liquefaction & debris caused extreme difficulty in accessing & constructing external water injection
line.
line.
● Insufficient injection ability of external water pump.
● Insufficient injection ability of external water pump.
● Securing and supplying alternative water source was prolonged.
● Securing and supplying alternative water source was prolonged.
PCV vent function was lost. Manual ventilation was delayed.
PCV vent function was lost. Manual ventilation was delayed.
● Lack of easy depressurization method under DC loss. Not prepared for working under high radiation.
● Lack of easy depressurization method under DC loss. Not prepared for working under high radiation.
● Other than W/W vent, there was no operation procedure or device to prevent fission products from● Other than W/W vent, there was no operation procedure or device to prevent fission products fromleaking outside, when conducting dry-well vent or other direct ventilation.
leaking outside, when conducting dry-well vent or other direct ventilation.
Lack of precaution, monitoring, and actions against building explosion (hydrogen explosion).
Lack of precaution, monitoring, and actions against building explosion (hydrogen explosion).
● No preparation for building ventilation in case of long-term AC power loss.
● No preparation for building ventilation in case of long-term AC power loss.
● No mechanism to detect hydrogen generation.
● No mechanism to detect hydrogen generation.
● No method to release accumulated hydrogen outside of the reactor building.
● No method to release accumulated hydrogen outside of the reactor building.
Emergency facilities at sea side were so vulnerable that they could not do almost anything after
Emergency facilities at sea side were so vulnerable that they could not do almost anything after
the loss of ultimate heat sink.
the loss of ultimate heat sink.
● Though overall AM procedure of ‘high pressure cooling => core depressurization => water injection by● Though overall AM procedure of ‘high pressure cooling => core depressurization => water injection by
low pressure cooling => PCV depressurization” was defined, specific AM/operational procedures
72 in caselow pressure cooling => PCV depressurization” was defined, specific AM/operational procedures in caseof simultaneous loss of all power & vent functions were not clearly defined.
of simultaneous loss of all power & vent functions were not clearly defined.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 2… Chronology… Progression of Accident

Extremely Confidential

Progression of the accident: As the explosion of adjacent units damaged the power
supply vehicle & fire truck, the recovery actions delayed, leading to the PCV damage.
3/11 14:46

Emergency
shutdownof thereactor

EventsEarthquake occurred (Level 6+)

Progression of accident (conceptual)(M9.0. 4th in recorded history）

Earthquake occurs● 14：47 Automatic shutdown of the reactor.
● Loss of all external power => Emergency DG automatically activated.
14:50 RCIC activated manually => 14:52 Stopped automatically (high water level = L-8).
● 15:01 Sub-criticality of the core confirmed

Tsunami hit
15:35
Loss ofall power&
seawatercoolingfunctions

15:39 RCIC activated manually.
●
15:41 All AC power lost (emergency DG & electrical panel immersed) =>Extreme work environment, darkness.
Battery room submerged & All DC power lost (some P/C not submerged). => RCIC
continued. Seawater systems submerged & ultimate heat sink lost. =>Function for cold shutdown lost.
17:12 Plant manager ordered to consider water injection by fire truck.
22:00 Core water level became readable (TAF +3400mm)
3/12

Secure highpressure
cooling.

(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

2:55
17:30

3/13

11:00

Prepare forlow pressure 3/14
coolant
injection.

11:01

Prepare forventilation

13:25
17:17

Confirmed RCIC was in operation.
(As RCIC confirmed as working, prioritized ventilation of Unit 1 at first.)
Plant manager ordered to prepare for PCV vent.
S/C vent valve (large) opened &vent-line structured.
(As D/W pressure was low, rupture disk did not rupture & ventilation failed).
Unit 3 exploded & excitation circuit for electro-magnetic valve damaged. S/C vent valve(large) closed and unable to open again. Also, explosion destroyed the fire truck andmakeshift hoses & water injection lines were unusable.
Reduction trend of reactor’s water level confirmed. => Judged as RCIC not working.
Reactor’s water level reached at TAF.

17:17~ Core damage started (estimated)Core depressurized.
LP coolant
injection.
Tried & failed
ventilation.
Core damage &hydrogen built
up.
3/15

18:00
18:22
19:54
21:00
22:50
23:35

0:02
PCV damaged.
Radiation leak.

6:00~
6:10

Started core de-pressurization (core pressure = 5.4MPa => 19:03 0.63MPa)
Water level reached at TAF -3700mm. Judged as core was exposed. => Reported to
METI.
Started sea water injection to the core with fire pump system & fire trucks.
S/C vent valve (small) slightly opened & reconstruction of vent line completed.
While D/W pressure exceeds maximum usage pressure 427kPa (& kept rising), S/C
pressure stayed at 300~400 kPa gage, and both pressures (DW & S/C) did not converge.
As rupture disk of S/C did not rupture (insufficient pressure), they decided to vent via
D/W by opening small valve.
Opened D/W vent valve (small) & vent line structured. (but, the valve closed again a few
minutes later). (D/W pressure did not drop below 750kPa (abs) & stayed at high level.)(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

External event
Countermeasures taken
Problem occurred orprogressed

Loss of all external
power (AC)Automatic activation of
emergency DGCore cooling by RCIC
Tsunami hit
Loss of all power(AC, DC, emergency DG)
Loss of water injection

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

Release gas from PCV(Manual vent)Core de-pressurization

D/W pressure rose
by failure of ventCore damage starts
with massive FP & H2

S/C pressure= 0 MPa (abs)

Water injection and coolingby fire truck, etc.

73

S/C pressure indicated at 0kPa(abs)
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 2… Deduced Problems…

Extremely Confidential

Problems deduced from the events at Fukushima Dai-ichi Unit 2
Progression of accident (conceptual)
Emergency
shutdownof thereactorEarthquake occurs(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

Loss ofall power&
seawatercoolingfunctions

Loss of all external
power (AC)Automatic activation of
emergency DGCore cooling by RCIC
Tsunami hit

Secure highpressure
cooling.
Prepare forlow pressure
coolant
injection.
Prepare forventilation

Core depressurized.

Loss of all power(AC, DC, emergency DG)
Loss of water injection

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

Release gas from PCV(Manual vent)Core de-pressurization

LP coolant
injection.
Tried & failed
ventilation.
Core damage &hydrogen builtup.

PCV damaged.
Radiation leak.

D/W pressure rose
by failure of vent
S/C pressure= 0 MPa (abs)Core damage starts
with massive FP & H2
Water injection and coolingby fire truck, etc.

Problems
AC power was lost over the long-term due to earthquake and tsunami.
AC power was lost over the long-term due to earthquake and tsunami.
● As Unit 1 also lost power, the power could not be shared with Unit 2.
● As Unit 1 also lost power, the power could not be shared with Unit 2.
● Though some electrical panels had survived, it was so difficult to access the building due to obstacles● Though some electrical panels had survived, it was so difficult to access the building due to obstacles
such as numerous debris that the recovery of power was delayed.
such as numerous debris that the recovery of power was delayed.
● As the power supply vehicle was destroyed by the explosion at Unit 1, they could not use the vehicle to● As the power supply vehicle was destroyed by the explosion at Unit 1, they could not use the vehicle topower the survived panel.
power the survived panel.
AM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longAM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longterm).
term).
● It was not assumed that the all batteries (DC) were submerged and lost spontaneously (lead to the loss of● It was not assumed that the all batteries (DC) were submerged and lost spontaneously (lead to the loss ofmonitoring function such as water level, status of RCIC etc).
monitoring function such as water level, status of RCIC etc).
● Due to all power loss, they could not remotely open the valves for ventilation.
● Due to all power loss, they could not remotely open the valves for ventilation.
● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure
handbook for SBO only assumed that DC power was normal).
handbook for SBO only assumed that DC power was normal).
Securing alternative cooling water source was insufficient and delayed.
Securing alternative cooling water source was insufficient and delayed.
● Due to power loss, core depressurization was delayed (battery depletion, insufficient pressure of air compressor).
● Due to power loss, core depressurization was delayed (battery depletion, insufficient pressure of air compressor).
● The fire truck and hoses were destroyed by the explosion at Unit 3.
● The fire truck and hoses were destroyed by the explosion at Unit 3.
● Liquefaction & debris, combined with frequent aftershocks, caused extreme difficulty in accessing &● Liquefaction & debris, combined with frequent aftershocks, caused extreme difficulty in accessing &constructing external water injection line.
constructing external water injection line.

PCV vent function was lost. Manual ventilation was delayed.
PCV vent function was lost. Manual ventilation was delayed.
● Due to the explosion at Unit 3, the large valve of PCV vent line was closed and unable to be opened any● Due to the explosion at Unit 3, the large valve of PCV vent line was closed and unable to be opened any
more. The operation to open small valve was also delayed.
more. The operation to open small valve was also delayed.
● Even when dry-well (D/W) pressure exceeded the activation pressure of rupture disk (destruction valve),● Even when dry-well (D/W) pressure exceeded the activation pressure of rupture disk (destruction valve),
wet well (W/W) pressure was below the activation pressure. So the rupture disk did not activate andwet well (W/W) pressure was below the activation pressure. So the rupture disk did not activate andcontinued to be so. After a while, as the pressure of suppression chamber (S/C) dropped, there was acontinued to be so. After a while, as the pressure of suppression chamber (S/C) dropped, there was a
possibility of PCV damage.
possibility of PCV damage.
● It is necessary to review the activation pressure of rupture disk.
● It is necessary to review the activation pressure of rupture disk.
Emergency facilities at sea side were so vulnerable that they could not do almost anything after
Emergency facilities at sea side were so vulnerable that they could not do almost anything after
the loss of ultimate heat sink.
the loss of ultimate heat sink.
● Though overall AM procedure of ‘high pressure cooling => core depressurization => water injection by● Though overall AM procedure of ‘high pressure cooling => core depressurization => water injection by
low pressure cooling => PCV depressurization” was defined, specific AM/operational procedures in caselow pressure cooling => PCV depressurization” was defined, specific AM/operational procedures in caseof simultaneous loss of all power & vent functions were not clearly defined.
of simultaneous loss of all power & vent functions were not clearly defined.

74
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 3… Chronology… Progression of Accident

Progression of the accident: Loss of important functions and delay in recovery actions
lead to the explosion.
Progression of accident (conceptual)
EventsEmergency
shutdownof thereactor3/11 14:46

Earthquake occurred (Level 6+)● 14：47 Automatic shutdown of the reactor. => 15:05 RCIC activated manually =>15:25 RCIC tripped (high water level).
● Loss of all external power => 14:48 Emergency DG automatically activated.
15:35

Earthquake occurs(M9.0. 4th in recorded history）

Tsunami hit(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

External event
Countermeasures taken
Problem occurred orprogressed

Loss of all external
power (AC)(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

Automatic activation of
emergency DG

Loss of all AC power + darkness & terrible work environment.

Loss ofall power&
seawatercoolingfunctions● Emergency DG & power panels flooded => 15:38 all AC power lost => Unable to use
electrical equipments.
● Seawater pump destroyed => Function for cold-shutdown lost. (ultimate heat sinklost)
● DC main lines survived. (Kept supplying DC power by backup batteries to RCIC, HPCI,
measurement instruments).

Core cooling by RCIC
Tsunami hit

16:03 Core cooling by RCIC (manually activated)

DC survived
then run out.

3/12

11:36 RCIC stopped (fire trucks used for Unit 1).
12:35 High pressure water injection (HPCI) automatically activated (water level = low).
17:30 Plant manager ordered to prepare for PCV vent.

3/13

02:42
03:51
04:15
05:10
05:15
08:41

RCIC/HPCI
worked thenlost.
Prepare forventilation

LP coolant
injection.
Conducted
PCV
ventilation.
Core damage& hydrogen
3/14
built up.

HPCI stopped (battery depleted).
Water level indicated as 1600mm below the fuel top (= TAF -1600mm).
Judged the water level reached at TAF.
Judged that RCIC failed to inject coolant.
Plant manager ordered to construct vent line systems.
Vent line excluding RD had been set up.

Loss of all power(AC, DC, emergency DG)
Core cooling by HPCI
Loss of water injection

08：00 ~ 09：00 Core damage started (estimated)

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

09:08
09:25
09:36
10:30
11:17
12:20

Release gas from PCV(Manual vent)Core de-pressurization

Core de-pressurized by SRV (used car batteries of workers).
Started fresh water injection by fire trucks (with boric acid).
Confirmed D/W pressure dropped after vent operation.
Plant manager ordered to prepare sea water injection.
AO valve of S/C vent closed (pressure of air compressor lowered).
Fresh water injection completed (since fresh water in fire protection water tankdepleted).
12:30 AO valve of S/C vent opened (air compressor changed).
13:12 Started sea water injection by fire trucks (frequent aftershocks delayed
its preparation).

01:10
03:20
05:20
09:20
10:53

Seawater injection by fire trucks stopped for replenishing, due to lack of sea water.
Seawater injection resumed.
S/C vent AO valve opened. 06:10 Confirmed the AO valve opened.
Started to supply seawater from the wharf to reverse-valve pit. (retarded by highradiation level & bad transportation)
7 water supply vehicles (5t) brought in by Self-Defense Force. Placed them toreverse valve pit & re-started fresh water injection.

H2 leaks into

reactor bldg from PCVCore damage starts
with massive FP & H2
Water injection and coolingby fire truck, etc.

75
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 3… Chronology… Progression of Accident

EventsHydrogen
Explosion &radiation leak

3/15

11:01

Progression of accident (conceptual)

Reactor building exploded (4th& 5th floor)
Fire truck and hoses were destroyed & seawater injection suspended.

16:30 Injection line from the wharf to the core was constructed. Sea water
injection resumed.

Hydrogen explosion
at reactor bldg

Fission products
released

07:55 Floating of moisture above the building confirmed.

76
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 3… Deduced Problems…

Extremely Confidential

Problems deduced from the events at Fukushima Dai-ichi Unit 3
Emergency
shutdownof thereactor

Progression of accident (conceptual)

Problems

Earthquake occurs

AC power was lost over the long-term due to earthquake and tsunami.
AC power was lost over the long-term due to earthquake and tsunami.
● As Unit 2 & 4 also lost power, the power could not be shared with Unit 3.
● As Unit 2 & 4 also lost power, the power could not be shared with Unit 3.
● Due to submergence of electrical panel, the loss of all AC power was prolonged.
● Due to submergence of electrical panel, the loss of all AC power was prolonged.
● Due to extremely bad environment, even after the power supply vehicles arrived, reaching power● Due to extremely bad environment, even after the power supply vehicles arrived, reaching power
connection port, and connection itself was difficult.
connection port, and connection itself was difficult.

(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

Loss of all external
power (AC)Automatic activation of
emergency DG

Loss ofall power&
seawatercoolingfunctionsCore cooling by RCIC
Tsunami hit

DC survived
then run out.
RCIC/HPCI
worked thenlost.

Loss of all power(AC, DC, emergency DG)
Core cooling by HPCI
Loss of water injection

Prepare forventilation

LP coolant
injection.

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

Release gas from PCV(Manual vent)Core de-pressurization

Conducted
PCV
ventilation.
Core damage& hydrogen
built up.

Hydrogen
Explosion &radiation leak

H2 leaks intoCore damage starts
with massive FP & H2

reactor bldg from PCV

Water injection and coolingby fire truck, etc.

Hydrogen explosion
at reactor bldg

Fission products
released

AM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longAM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longterm).
term).
● As batteries were not submerged, the high pressure cooling system worked for a while. However, with● As batteries were not submerged, the high pressure cooling system worked for a while. However, withbatteries depleted, water injection function was lost.
batteries depleted, water injection function was lost.
● Due to all power loss, they could not remotely open the valves for SRV ventilation.
● Due to all power loss, they could not remotely open the valves for SRV ventilation.
● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure
handbook for SBO only assumed that DC power was normal).
handbook for SBO only assumed that DC power was normal).
Securing alternative cooling water source was insufficient and delayed.
Securing alternative cooling water source was insufficient and delayed.
● As the batteries were insufficient, they collected and brought in individual car batteries to open SRV.
● As the batteries were insufficient, they collected and brought in individual car batteries to open SRV.
This had delayed the depressurization.
This had delayed the depressurization.
● It took much time to procure alternative fire trucks other than the one used at Unit 1, which was only
● It took much time to procure alternative fire trucks other than the one used at Unit 1, which was only
available then.
available then.
● Water injection was delayed due to insufficient seawater source and lack of fire trucks.
● Water injection was delayed due to insufficient seawater source and lack of fire trucks.
● Liquefaction & debris caused extreme difficulty in transporting fire trucks & constructing external water● Liquefaction & debris caused extreme difficulty in transporting fire trucks & constructing external water
injection line/hose.
injection line/hose.
PCV vent function was lost. Manual ventilation was delayed.
PCV vent function was lost. Manual ventilation was delayed.
● Lack of easy depressurization method under DC loss. Not prepared for working under high radiation.
● Lack of easy depressurization method under DC loss. Not prepared for working under high radiation.
● Other than suppression pool scrubbing, there was no operation procedure or device to prevent fission● Other than suppression pool scrubbing, there was no operation procedure or device to prevent fission
products from leaking outside, when conducting dry-well vent or other direct ventilation.
products from leaking outside, when conducting dry-well vent or other direct ventilation.
Lack of precaution, monitoring, and actions against building explosion (hydrogen explosion).
Lack of precaution, monitoring, and actions against building explosion (hydrogen explosion).
● No preparation for building ventilation in case of long-term AC power loss.
● No preparation for building ventilation in case of long-term AC power loss.
● No mechanism to detect hydrogen generation.
● No mechanism to detect hydrogen generation.
● No method to release accumulated hydrogen outside of the reactor building.
● No method to release accumulated hydrogen outside of the reactor building.
Emergency facilities at sea side were so vulnerable that they could not do almost anything after
Emergency facilities at sea side were so vulnerable that they could not do almost anything after
the loss of ultimate heat sink.
the loss of ultimate heat sink.
● Though overall AM procedure of ‘high pressure cooling => core depressurization => water injection by● Though overall AM procedure of ‘high pressure cooling => core depressurization => water injection by
low pressure cooling => PCV depressurization” was defined, specific AM/operational procedures in caselow pressure cooling => PCV depressurization” was defined, specific AM/operational procedures
77 in caseof simultaneous loss of all power & vent functions were not clearly defined.
of simultaneous loss of all power & vent functions were not clearly defined.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 4… Chronology… Progression of Accident

Progression of the accident: Loss of SFP cooling function raised water temperature, andthe hydrogen flowed into the reactor building from Unit 3, leading to the explosion.
Events

3/11 14:46
Emergency
shutdownof thereactor(M9.0. 4th in recorded history）(M9.0. 4th largest in recorded history)

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)

Decrease in SFP waterlevel by sloshing

External event
Countermeasures taken
Problem occurred orprogressed

Loss of all external
power (AC)Automatic activation of
emergency DG

Loss of all AC power + darkness & terrible work environment.
● Emergency DG & power panels flooded => all AC power lost => Unable touse electrical equipments.
● Battery room submerged => DC power lost => Electrical board, measurement/
controlling facilities malfunctioned. => Cooling function lost (RHR).
● Seawater pump for Fuel Pool Cooling & Filtering (FPC) system damaged. =>Cooling function lost (ultimate heat sink lost).

Water level ofSFP
monitored.

As the pool temperature continued to rise by the decay heat ofused fuel, water level in the pool decreased with its water
evaporated.

Prepare to
maintainwater level.

● The water level was estimated to reach to the top of fuel rods around March
20th.
● Since the pool gate was closed before earthquake, the water level was thesame as the one at the well side of DS pit. So, it was reasonably expected thatthe pool gate would open to supply water to SFP from the well side if thewater level in SFP continue to drop.

Hydrogenflowed backfrom Unit 3.

3/14

04:08 SFP temperature was confirmed as 84 ℃.
11:01 Unit 3 explosion

Hydrogen
3/15 06：12
Explosion &radiation leakwater
injection
started.

Earthquake occurs● Under regular inspection from November 30
rods of spent fuel stored in SFP(97% full).
● Loss of all external power => 14:47 Emergency DG automatically activated.
● Water sloshed & spilled over from the pool & water level dropped (approx. 0.5m)

Loss ofall power&
seawatercoolingfunctionsextinguished.

Earthquake occurred (Level 6+)th, 2009, (reactor was on halt). = 1535

15:35

Fire brokeout &Progression of accident (conceptual)

Tsunami hit
Loss of all power(AC, DC, emergency DG)
Loss of seawater
pump system
Loss of cooling function

Temperature of
SFP water rose
Hydrogen explosion
at 4 & 5 F of reactor bldg

Huge detonation sound.
Reactor building severely damaged (4th & 5th floor)● Pool gate opened due to explosion, and water level recovered up to well level (estimated).
3/16 09:38 Fire broke out from the 3
11:00 Fire extinguished naturally.
Water level confirmed from helicopter (4-5m above the fuel top)rd floor of the reactor building.

3/20 08:21 Started to spray water to the SFP (continued periodically).

Fire broke out at 3rd floor=> Ceased naturally
Water injection to
SFP started

78

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Fukushima Dai-ichi Unit 4… Deduced Problems…

Extremely Confidential

Problems deduced from the events at Fukushima Dai-ichi Unit 4
Progression of accident (conceptual)
Emergency
shutdownof thereactor

Loss ofall power&
seawatercoolingfunctions

Earthquake occurs(M9.0. 4th largest in recorded history)

Decrease in SFP waterlevel by sloshing

Loss of all external
power (AC)Automatic activation of
emergency DG

Tsunami hit
Loss of all power(AC, DC, emergency DG)

Water level ofSFP
monitored.
Prepare to
maintainwater level.
Hydrogenflowed backfrom Unit 3.

Hydrogen
Explosion &radiation leak
Fire brokeout &extinguished.

water
injection
started.

Loss of seawater
pump system
Loss of cooling function

Temperature of
SFP water rose
Hydrogen explosion
at 4 & 5 F of reactor bldg

Problems
AC power was lost over the long-term due to earthquake and tsunami.
AC power was lost over the long-term due to earthquake and tsunami.
● As Unit 3 also lost power, the power could not be shared with Unit 4.
● As Unit 3 also lost power, the power could not be shared with Unit 4.
● Although one emergency DG survived and was activated, there was no additional power source.
● Although one emergency DG survived and was activated, there was no additional power source.
● Drop in water level by sloshing was expected.
● Drop in water level by sloshing was expected.

AM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longAM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for longterm).
term).
● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure
handbook for SBO only assumed that DC power was normal).
handbook for SBO only assumed that DC power was normal).
● Countermeasures, preparation, and training in case of simultaneous loss of power, cooling & vent● Countermeasures, preparation, and training in case of simultaneous loss of power, cooling & ventfunctions were inadequate.
functions were inadequate.

The building explosion (hydrogen explosion).
The building explosion (hydrogen explosion).
● Although it was an unexpected explosion and the reason was unknown, TEPCO assumed that the● Although it was an unexpected explosion and the reason was unknown, TEPCO assumed that thehydrogen generated in Unit 3 had flowed into Unit 4 through the pipelines for stand-by gas treatmenthydrogen generated in Unit 3 had flowed into Unit 4 through the pipelines for stand-by gas treatment
system (SGTS), and exploded. (No damage of fuel rods in SFP of Unit 4).
system (SGTS), and exploded. (No damage of fuel rods in SFP of Unit 4).
=> Radiation levels of radiation removal filters for SGTS were a couple of ten times higher at the=> Radiation levels of radiation removal filters for SGTS were a couple of ten times higher at theexhaust side than at the intake side.
exhaust side than at the intake side.
● Cause of fire was also unknown. It could be caused by the combustion of hydrogen.
● Cause of fire was also unknown. It could be caused by the combustion of hydrogen.
● No preparation for building ventilation in case of long-term AC power loss.
● No preparation for building ventilation in case of long-term AC power loss.
● No mechanism to detect hydrogen generation.
● No mechanism to detect hydrogen generation.
● No method to release accumulated hydrogen outside of the reactor building.
● No method to release accumulated hydrogen outside of the reactor building.

Emergency facilities at sea side were so vulnerable that they could not do almost anything after
Emergency facilities at sea side were so vulnerable that they could not do almost anything after
the loss of ultimate heat sink.
the loss of ultimate heat sink.
● Due to submergence of the seawater cooling pumps, combined with loss of all AC power, SFP cooling● Due to submergence of the seawater cooling pumps, combined with loss of all AC power, SFP cooling
function was lost.
function was lost.

Fire broke out at 3rd floor=> Ceased naturally
Water injection to
SFP started

79
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima
FukushimaDai-ni
Dai-niPowerPowerPlant:
Plant:
Chronologies
ChronologiesandandIssues
Issues80
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Fukushima Dai-ni… External Power

Damage to external power: At Fukushima Dai-ni, 3 out of 4 external power lines werelost due to the damage of transforming equipments at substations.
SupplySupplyroute
routeofofexternal
externalpower
power
・・ Fukushima
FukushimaDai-ni
Dai-niusuallyusuallyreceives
receives
power
fromShin-Fukushima
power from Shin-Fukushima
substation,
substation,88km
kmawayawayfrom
fromthetheplant.
plant.

Fukushima Dai-ni Nuclear Power Plant

Startup transformer
Iwaido line No. 1 & 2

66kV switching station

Unit 4

Unit 3
Of 4 lines of 2 systems,
3 lines were lost & 1 line
was active.

Unit 2Power
Powersupply
supplyfrom
fromthethesubstation
substation
=>
3
out
of
4
lines
were
=> 3 out of 4 lines weredown
down
due
to
earthquake
due to earthquake

Tomioka line No.1&2

Unit 1
Shin Fukushima
Substation
Shin-Iwaki
Switching Station

Extra high voltage
switching station

Startup transformer

Status of Nuclear Power Plants after Tohoku Region Pacific Coast Earthquake (March, 22, 2011. TEPCO)

Pacific
Ocean

・・ Facilities
Facilitiessuch
suchasasbreakers
breakerswereweredamagedbystrongseismic
motiondamaged by strong seismic motionatat
Shin
ShinFukushima
Fukushimasubstation.
substation.
・・ 22out
outofof44transmission
transmissionlines*
lines*totoDai-ni
Dai-ni
Units
1-4
were
stopped.
Units 1-4 were stopped.
(*:(*:22lines
linesofof11systems
systems(500(500kV),kV),andand22linesof1system(66kV)).
lines of 1 system (66kV)).
( (11line
line(66kV)(66kV)alreadyalreadyon
onhalthaltbefore
beforeearthquake).
81
earthquake).

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Fukushima Dai-ni …Power Loss…

Loss of external and internal power after tsunami: At Fukushima Dai-ni, 1 external
power line and 3 internal power lines (emergency DG) survived.
Transmission
maintained
TomiokaLine 1L

Stopped underregular inspection

IwaidoLine 1L

TomiokaLine 2L

IwaidoLine 2L

66kV main line

External power loss
● Iwaido Line 1L: Had stopped for regular inspection before
earthquake.
● Iwaido Line 2L: Not stopped by earthquake. (However, a defect(damage in lightning protector at substation) was found & stopped
for repairs. Recovered the day after).
● Tomioka line 2L： Stopped due to earthquake (= damage indisconnector)

500kV main line
High activationtransformer

Loss of emergency DG

Startup transformer
for Units 1 &2

Startup transformer
For Units 3 & 4● 3 emergency DG’s wereplaced in each unit.
● Units 1&2: All lost due totsunami.
● Unit 3: 1 unit lost, 2 sound.
● Unit 4: 2 lost, 1 sound.

6.9kV main line

6.9kV main line

6.9kV main line

6.9kV main line

: Stopped due to earthquake
D/G
１Ｈ

D/G
１Ａ

D/G
１Ｂ

Unit 1 emergency power

D/G
２Ｈ

D/G

D/G

D/G

D/G

D/G

D/G

２Ａ

２Ｂ

３Ｈ

３Ａ

３Ｂ

４Ｈ

Unit 2 emergency power

Unit 3 emergency power

D/G

D/G

４Ａ

４Ｂ

Unit 4 emergency power: Stopped due to tsunami: Active after tsunami

82
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Fukushima Dai-ni …Emergency DG

Extremely Confidential

Emergency DG: 3 out of 12 emergency DG survived at Fukushima Dai-ni. At Dai-ichi, all
but one at Unit 6 were lost.
Fukushima Dai-ichi: DG systems
Sea water cooling emergency DG (10 units)
Unit 1A/B, Unit 2A, Unit 3 A/B, Unit 4A, Unit 5A/B, Unit 6A/H
Seawater pump～～
Ocean～ ～Heat
海exchanger～～～～
Air cooling DG (3 units)
Unit 2B, Unit 4B, Unit 6B

All units lost theirfunctions after tsunami

DG

Cooling water pump
DG

Heat exchanger

Only Unit 6B functioned.
Air

Fukushima Dai-ni: DG systems
Sea water cooling DG (12 units)
Units 1~4 A/B/H
Sea water pump

Cooling water pump

Only Unit 3B, 3H and

～～
Ocean
～
海
～～
～～

Heat
exchanger

DG

Unit 4H functioned.

If the cooling system for DG is lost, the entire DG system would be lost even though
83 DG
itself is active.

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Fukushima Dai-ni …Loss of Power

Extremely Confidential

Loss of power other than external power: At Fukushima Dai-ni, as the flooding damage
to reactor/turbine buildings was limited, the damage to electrical panels (MC, PC), DC
power, and seawater systems were less than that of Dai-ichi.
Loss of major power supply systems after tsunami
Unit 1
Electrical
panel
ＤＧ１Ａ
Emergency
ＤＧ

Emergency

ＤＧ1Ｂ

Fukushima Dai-ichi
Unit 3
Unit 4

Unit 2Usabil Electrical
ity panel××

Ｍ／Ｃ １Ｃ×

Ｍ／Ｃ １Ｄ

×

ＤＧ２Ａ
ＤＧ２Ｂ
（Air cooling）

Ｍ／Ｃ 2Ｃ

Usabil Electrical
ity panel×

ＤＧ３Ａ

×（※１） ＤＧ３Ｂ

Usabil Electrical
ity panel×××

Ｍ／Ｃ ３Ｃ×

Ｍ／Ｃ 3Ｄ×

Ｍ／Ｃ 2Ｄ×

Ｍ／Ｃ ２Ｅ

×

ＤＧ４Ａ
ＤＧ４Ｂ
（Air cooling）

Ｍ／Ｃ 4Ｃ

Unit 5Usabil Electrical
ity panel×

ＤＧ５Ａ（※２）

×（※１） ＤＧ５Ｂ（※２）

Unit 6

Usabil Electrical
ity panel×××

Ｍ／Ｃ 5Ｃ×

Ｍ／Ｃ 5Ｄ×

Ｍ／Ｃ 4Ｄ×

Ｍ／Ｃ 4Ｅ×

Ｍ／Ｃ １Ａ×

Ｍ／Ｃ 2Ａ×

Ｍ／Ｃ ３Ａ×

Ｍ／Ｃ 4Ａ×

Ｍ／Ｃ 5Ａ×

Ｍ／Ｃ １Ｂ×

Ｍ／Ｃ 2Ｂ×

Ｍ／Ｃ ３Ｂ×

Ｍ／Ｃ 4Ｂ×

Ｍ／Ｃ 5Ｂ×

M/C 5SA-1

×

M/C 5SA-2

×

M/C 5SB-1

×

M/C 5SB-2

×

Ｍ／Ｃ
Normal

Ｍ／Ｃ １Ｓ

Emergency

Ｍ／Ｃ ３SA×

Ｍ／Ｃ ２SB×

Ｍ／Ｃ ３SB×

Sea water
systemUsabil Electrical
ity panel

×（※2）

ＤＧ１Ａ

×

Unit 4Usabil Electrical
ity panel

Usabil Electrical
ity panel

UsabilityＤＧ２Ａ

×（※2） ＤＧ３Ａ

×（※2） ＤＧ４Ａ

×（※2）

○

ＤＧ1Ｂ

×

ＤＧ２B

×（※2） ＤＧ３Ｂ

○

ＤＧ４Ｂ

ＨＰＣＳ ＤＧ

×（※2）

ＤＧ1H

×

ＤＧ2H

×（※2） ＤＧ3H

○

ＤＧ4H

○

Ｍ／Ｃ 6Ｃ○

Ｍ／Ｃ １Ｃ×

Ｍ／Ｃ 2Ｃ○Ｍ／Ｃ 3Ｃ○Ｍ／Ｃ 4Ｃ○○（Air cooling）

×（※2）

Ｍ／Ｃ 6Ｄ○

Ｍ／Ｃ １Ｄ○Ｍ／Ｃ 2Ｄ○Ｍ／Ｃ 3Ｄ○

Ｍ／Ｃ 4Ｄ

HPCS DG M/C○Ｍ／Ｃ １H×

Ｍ／Ｃ 2H○

Ｍ／Ｃ 3H○

Ｍ／Ｃ 4H○

M/C 6A-1

×

M/C 1A-1○

M/C 2A-1○

M/C 3A-1○

M/C 4A-1○

M/C 6A-2

×

M/C 1A-2○

M/C 2A-2○

M/C 3A-2○

M/C 4A-2○

M/C 6B-1

×

M/C 1B-1○

M/C 2B-1○

M/C 3B-1○

M/C 4B-1○

M/C 6B-2

×

M/C 1B-2○

M/C 2B-2○

M/C 3B-2○

M/C 4B-2○

M/C 1SA-1○

M/C 3SA-1○

M/C 1SA-2○

M/C 3SA-2○

M/C 1SB-1○

M/C 3SB-1○

M/C 1SB-2○

M/C 3SB-2○○

P/C ２C○P/C ３C×

P/C 4C-P/C 5C×

P/C 6C○P/C 1C-1

×

P/C 2C-1○

P/C 3C-1○

P/C 4C-1

P/C 1D×

P/C ２D○P/C ３D×

P/C 4D○P/C 5D×

P/C 6D○P/C 1C-2

×

P/C 2C-2

×

P/C 3C-2

×

P/C 4C-2

×

P/C ２Ｅ×

P/C 4Ｅ×

P/C 6E○P/C 1D-1○

P/C 2D-1○

P/C 3D-1○

P/C 4D-1○

P/C ２Ａ○P/C 4Ａ-P/C ２Ａ-１

×

P/C ２Ｂ○P/C 1S××

ＤＣ１２５Ｖ
main&transfer
bus 1Ａ
ＤＣ１２５Ｖ
main&transfer
１２５ＶＤＣ bus 1Ｂ

××

P/C ３ＡP/C ３ＢP/C ３ＳＡ×
P/C ２ＳＢ

DC
power

Electrical
panel

×

P/C 1B
Normal×

ＤＧ６Ｂ

Usability

P/C 1CP/C 1A
Ｐ／Ｃ

Ｍ／Ｃ ２SA×

ＤＧ６Ａ

Fukushima Dai-ni
Unit 2
Unit 3

Unit 1ＤＣ１２５Ｖ
main&transfer
bus 2Ａ
ＤＣ１２５Ｖ
main&transfer
bus 2Ｂ×××

P/C ３ＳＢ

ＤＣ１２５Ｖ
main&transfer
bus 3Ａ
ＤＣ１２５Ｖ
main&transfer
bus 3Ｂ××

P/C 4Ｂ

○

×

×

○

○

ＤＣ１２５Ｖ
main&transfer
bus ４Ａ
ＤＣ１２５Ｖ
main&transfer
bus ４Ｂ××

P/C 5Ａ×

P/C 6Ａ-1

×

P/C 1D-2

×

P/C 2D-2

×

P/C 3D-2○

P/C 4D-2

×

P/C 5Ａ-1○

P/C 6Ａ-2

×

P/C 1A-1○

P/C 2A-1○

P/C 3A-1○

P/C 4A-1○

P/C 5B×

P/C 6B-1

×

P/C 1A-2○

P/C 2A-2○

P/C 3A-2○

P/C 4A-2○

P/C 5B-1○

P/C 6B-2

×

P/C 1B-1○

P/C 2B-1○

P/C 3B-1○

P/C 4B-1○

P/C 2B-2○

P/C 4B-2○

P/C 5SＡ×

P/C 1B-2○

P/C 3B-2○

P/C 5SＡ-1

×

P/C 1SA○P/C 3SA○P/C 5SB×

P/C 1SB○

P/C 3SB○

ＤＣ１２５Ｖ
main&transfer
bus 5Ａ
ＤＣ１２５Ｖ
main line
board 5Ｂ○○

ＤＣ１２５ＶDIST CENTER 6Ａ

ＤＣ１２５ＶDIST CENTER 6B○○

ＤＣ１２５Ｖ
main line
boardＡ
ＤＣ１２５Ｖ
main line
board Ｂ○○

ＤＣ１２５Ｖ
main&transfer
bus Ａ
ＤＣ１２５Ｖ
main&transfer
bus Ｂ

○

○

ＤＣ１２５Ｖ
main&transfer
bus Ａ
ＤＣ１２５Ｖ
main&transfer
bus Ｂ

○

○

ＤＣ１２５Ｖ
main&transfer
bus Ａ
ＤＣ１２５Ｖ
main&transfer
bus Ｂ

○

○

A/B

Ａ

CCS A

×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ

Ｂ

CCS B

×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ○ＲＨＲＳ Ｂ

HPCS DGSW

×

HPCSS

×

HPCSS

×

HPCSS

○

HPCSS

: Lost functions: Unable to activate due to electrical board and/or cooling system were lost
: Incoming power was inaccessible due to the loss of electrical supply source

84

×
×
○

Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Fukushima Dai-ni Unit 1…Chronology

Chronology of Fukushima Dai-ni Unit 1 (Before earthquake: regular operation)
EventsEmergency
shutdown of
the reactor

3/11 14:46 Earthquake occurred (Level 6+)(M9.0. 4th in recorded history）● 14：48 Reactor automatically shutdown. All control rods inserted. Main
turbines automatically shut down. Core water level was low (L-3). 1 transmission
system (500kV) stopped. External power secured with remaining 1 system.
● 15:00 Core sub criticality confirmed.

15:22
Loss ofemergency
equipments
by tsunami

Maintainedcorepressure &water level.
Depressurized
RPV.
Started corecooling.

Restored
power
supply &emergency
equipments.
Cold
shutdown.

Implications

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 12~ 14.5m)

15:33 Water circulation pump (C) manually stopped.
15:34 Emergency DG (A), (B), (H) automatically activated => But stopped
immediately due to tsunami.
15:36 MSIV all closed manually.
RCIC manually activated (for water injection to nuclear reactor).
15:40 After RCIC pump automatically stopped (core water level (L-8)),water level
continuously maintained with RCIC.
15:55 Started core depressurization by SRV & continued hereafter.
17：35 Warning of ‘dry-well (D/W) pressure is high’. => Automatic
activation signal for ECCS pump transmitted.
17:53 D/W cooling system manually activated.
●

3/12 0:00 Started water injection to the core by MUWC.

●
・
・
●
・
・

●
・

・
・

3:50 Started rapid core depressurization.
4:56 Rapid core depressurization completed.
4:58 RCIC manually stopped.
6:20 Cooling of suppression chamber (S/C) by MUWC using flammability
control system (FCS).
7:10 Conducted D/W spray by MUWC (continued arbitrarily henceforth).
7:37 Conducted S/C spray by MUWC (continued arbitrarily henceforth).
7:45 Stopped S/C cooling by FCS cooling water (MUWC).
10:21 Started construction of PCV pressure resistance vent line.
18:30 Construction of the above vent line completed.

●・

3/13 20:17 Activated RHRS (B) pump manually (power supplied through makeshift cable).

・

・

●
・

21:03 Activated RHRC (D) pump manual (power supplied through makeshift cable).

3/14 1:24 Activated RHR(B) pump manually (S/C cooling mode started).
1:44 Activated Emergency Equipment Cooling Water system (EECW) manually(power supplied by high-voltage power supply vehicle).
3:39 Started RHR(B) S/C spray mode.
10:05 Water injected to the core with RHR(B) LPCI mode.
10:15 Confirmed that S/C water temperature was below 100℃.
16:30 Started water injection to SFP by FWMUW.

●・・

Nuclear reactor automatically shutdown due to earthquake
The reactor reacted (scrammed) to earthquake in accordance with the design. No major problems
found.
Since external power survived, normal/emergency power source were secured.
Due to submergence by Tsunami, emergency DG, emergency power, & sea water pumpsystems were lost.
As the annex of reactor building & seawater heat exchange building were submerged, emergency
power systems (M/C, P/C) became unavailable.
Emergency DG were active before Tsunami. After Tsunami, all emergency DG were lost, since all theEmergency Equipment Cooling Water pumps, DG units & cooling pumps were flooded & lost theirfunctions.
Maintained core pressure & water level with SRV and RCIC.
Regarding reactor pressure control, since water condenser was unusable because of the loss of water
circulation pump (main steam could not be condensed), they closed all MSIV and depressurized thecore by SRV (as defined in the AM manual).
With all MSIV closed, they manually activated RCIC to inject water to the core.
Since the pressure of RPV & S/C was reaching to the warning range, they rapidly de-pressurized thecore by SRV, and prepared water injection by MUMC (i.e. prepare for low pressure cooling), thenstopped RCIC.
Warning of high pressure in Dry Well.
Warning was alerted as D/W pressure rose very high. This is because SRV was opened (i.e. main
steam flew into S/C from core) and the loss of RHR (i.e. PCV residual heat could not be removed).
Automatic activation signal for ECCS pump was transmitted because of high pressure in D/W. As thecooling pumps for RHR (B,C) were lost, RHR(B,C) was stopped manually after automatic activation.
Other ECCS pumps could not be activated.
Prepared to cool S/C & D/W of PCV as well as ventilation.
For S/C cooling, they injected water to S/C through drain line from FCS cooling device, and sprayedwater on to S/C & D/W by MUWC periodically.
Though they had structured the pressure resistance vent line to prepare for the rise in PCV pressure, it
had not reached to 310 kPa (= maximum designed pressure of PCV).
Achieved cold shutdown with the recovery of emergency cooling pump systems.
They recovered cooling function of RHR systems & emergency DG with power supply vehicles &makeshift cables which were supplied power from the external power line of the radioactive waste
processing building. With RHR (B) activated manually, they started S/C cooling.
Using LPCI line of RHR (B) system and SRV, they cooled the core with the heat exchanger of RHR
and achieved cold shutdown.

85

17:00 Cold shutdown achieved.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Fukushima Dai-ni Unit 2…Chronology

Chronology of Fukushima Dai-ni Unit 2 (Before earthquake: regular operation)
Implications

EventsEmergency
shutdown of
the reactor

3/11 14:46(M9.0. 4th in recorded history）● 14：48 Reactor automatically shutdown. All control rods inserted. Main
turbines automatically shut down. Core water level was low (L-3). 1 transmission
system (500kV) stopped. External power secured with remaining 1 system.
● 15:01 Core sub criticality confirmed.

15:22

Loss ofemergency
equipments
by tsunami

Cold
shutdown.

●
・
・
●
・
・

15:34 Emergency DG (H) automatically activated => But stopped immediately due to tsunami.
15:34 MSIV all closed manually.
15:35 Activated RHR (B) manually. => 15:38 stopped.
Stopped circulation water pump ((C) manually, (A, B) automatically).
15:41 Emergency DG (A)(B) automatically activated. => Sopped immediately due to●
Tsunami.
15:41 Started core depressurization by SRV & continued hereafter.
・
15:43 RCIC manually activated (for water injection to nuclear reactor). Continued hereafter.
●
18：50 Warning of ‘dry-well (D/W) pressure is high’. => Automatic
activation signal for ECCS pump transmitted.
・
20:02 D/W cooling system manually activated.

・

3/12
4:50 Started water injection to the core by MUWC.
4:53 RCIC automatically stopped (since core pressure went down).
6:30 Cooling of suppression chamber (S/C) by MUWC using flammability
control system (FCS).
7:11 Conducted D/W spray by MUWC (continued arbitrarily henceforth).
7:35 Conducted S/C spray by MUWC (continued arbitrarily henceforth).
Activated RHR (B) manually. => Cooled S/C.
7:52 Stopped S/C cooling by FCS cooling water (MUWC).
10:33 Started construction of PCV pressure resistance vent line.
10:58 Construction of the above vent line completed.

Started corecooling.

Restored
power
supply &emergency
equipments.

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 12~ 14.5m)

Maintainedcorepressure &water level.
Depressurized
RPV.

Earthquake occurred (Level 6+)

3/14

●
・
・

●
・
・

3:20 Activated EECW (B) manually (power supplied through makeshift cable).
3:51 Activated RHRS (B) pump manually (power supplied through makeshift cable).
5:52 Activated RHRC (D) pump manual (power supplied through makeshift cable).
7:13 Activated RHR(B) pump manually (S/C cooling mode started).
7:50 Started RHR(B) S/C spray mode.
10:48 Water injected to the core with RHR(B) LPCI mode.
15:52 Confirmed that S/C water temperature was below 100℃.

18:00 Cold shutdown achieved.

●・・

Nuclear reactor automatically shutdown due to earthquake
The reactor reacted (scrammed) to earthquake in accordance with the design. No major problems
found.
Since external power survived, normal/emergency power source were secured.
Due to submergence by Tsunami, emergency power & sea water pump systems werelost.
As the seawater heat exchange building was submerged, its emergency power systems (P/C) became
unavailable.
Emergency DG were active before Tsunami. However, all the Emergency Core Cooling System(ECCS) pump & emergency DG were lost, since all the Emergency Equipment Cooling Water(EECW) pumps were flooded & lost their functions with the seawater heat exchange building flooded.
Maintained core pressure & water level with SRV and RCIC.
Regarding reactor pressure control, since water condenser was unusable because of the loss of water
circulation pump (main steam could not be condensed), they closed all MSIV and depressurized thecore by SRV (as defined in the AM manual).
With all MSIV closed, they manually activated RCIC to inject water to the core.
As the core pressure dropped by SRV, RCIC stopped automatically. Then they changed to water
injection by MUWC, following the AM manual.
Warning of high pressure in Dry Well.
Warning was alerted as D/W pressure rose very high. This is because SRV was opened (i.e. main
steam flew into S/C from core) and the loss of RHR (i.e. PCV residual heat could not be removed).
Automatic activation signal for ECCS pump was transmitted because of high pressure in D/W. As the
EECW pumps were lost, the ECCS pumps were stopped manually.
Prepared to cool S/C & D/W of PCV as well as ventilation.
For S/C cooling, they injected water to S/C through drain line from FCS cooling device, and sprayedwater on to S/C & D/W by MUWC periodically.
Though they had structured the pressure resistance vent line to prepare for the rise in PCV pressure, it
had not reached to 310 kPa (= maximum designed pressure of PCV).
Achieved cold shutdown with the recovery of emergency cooling pump systems.
They recovered cooling pump function of RHR (B) systems & emergency DG with power supply
vehicles & makeshift cables, which were supplied power from the external power line in theradioactive waste processing building, as well as from the emergency power source in the heatexchange building at Unit 3. With RHR (B) activated manually, they started S/C cooling.
Using LPCI line of RHR (B) system and SRV, they cooled the core with the heat exchanger of RHR
and achieved cold shutdown.

86

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Fukushima Dai-ni Unit 3…Chronology

Chronology of Fukushima Dai-ni Unit 3 (Before earthquake: regular operation)
EventsEmergency
shutdown of
the reactor

3/11 14:46(M9.0. 4th in recorded history）● 14：48 Reactor automatically shutdown. All control rods inserted.
Main turbines automatically shut down. Core water level was low (L-3).
1 transmission system (500kV) stopped. External power secured withremaining 1 system.
● 15:05 Core sub criticality confirmed.

Loss ofemergency
equipments(system-A) bytsunami

15:22

16:06 Activated RCIC manually (water injection to reactor). Water leveladjustment continued.
16:48 Stopped water circulation pump (A) manually.

Depressurized
RPV.

● 19:46 Warning of ‘dry-well (D/W) pressure is high’. => Automatic
activation signal for ECCS pump transmitted.
=>
As the RHRC(A,C), RHRS(A,C), EECW(A) pumps were not available,
they switched off the automatic activation function of RHR(A,C) pump &LPCS pump in advance.
Then, they changed RHR(B) from S/C cooling mode to LPCI mode.

Started corecooling.

Cold
shutdown.

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 12~ 14.5m)

15:34 Stopped water circulation pump (C) manually.
15:35 Emergency DG (A), (B), (H) automatically activated. => DG (A) stopped
immediately due to tsunami.
15:36 Activated RHR(B) manually. (Started S/C cooling).
15:37 Closed all MSIV manually.
15:38 Stopped water circulation pump (B) manually.
15:46 Started core depressurization with SRV & continued henceforth.

Maintainedcorepressure &water level.

Used power
supply &emergency
equipments(system-B).

Earthquake occurred (Level 6+)

3/12

20:07
20:12
22:53
23:11

Switch RHR(B) from LPCI to S/C cooling mode.
Activated D/W cooling system automatically.
Started water injection to the core by MUWC.
Stopped RCIC manually (due to drop in nuclear reactor pressure).

0:06
1:23
2:39
2:41
7:59
9:37
12:08
12:13

Started to construct the RHR(B) reactor shutdown cooling system (SHC).
RHR(B) manually stopped (to prepare for SHC mode).
RHR(B) manually activated (S/C cooling mode started).
RHR(B) S/C spray mode started.
RHR(B) manually stopped (stopped S/C cooling & spray mode).
RHR(B) manually activated (SHC mode started).
Started to structure PCV pressure resistant vent line.
The construction of the vent line above completed.

12:15 Cold shutdown achieved.

Implications

●
・
・
●
・
・

●
・

・
・

●
・
・

●
・

Nuclear reactor automatically shutdown due to earthquake
The reactor reacted (scrammed) to earthquake in accordance with the design. No
major problems found.
Since external power survived, normal/emergency power source were secured.
Due to submergence by Tsunami, emergency power (A) & sea water pumpsystems (A) were lost.
Due to Tsunami, emergency power systems (some P/C) in the heat exchange building
became unavailable.
Emergency DG were active before Tsunami. However, the Emergency Core Cooling
System (ECCS) (A) pump & emergency DG (A) were lost, since the Emergency
Equipment Cooling Water (EECW) (A) pumps were lost with the seawater heatexchange building partially flooded,.
Maintained core pressure & water level with SRV and RCIC.
Regarding reactor pressure control, since water condenser was unusable because of
the loss of water circulation pump (main steam could not be condensed), they closed
all MSIV and depressurized the core by SRV (as defined in the AM manual).
With all MSIV closed, they manually activated RCIC to inject water to the core.
As the core pressure dropped by SRV, they prepared low-pressure cooling system,
MUWC, at first. Then they stopped RCIC manually.
Warning of high pressure in Dry Well.
Warning was alerted as D/W pressure rose very high. This is because SRV was opened
with main steam flowing into S/C.
Automatic activation signal for ECCS pump was transmitted because of high pressure
in D/W. As the EECW pumps (A) were lost, they had switched off its automatic
activation function beforehand. The ECCS pumps (B) were cooling S/C normally.
Achieved cold shutdown.
Using Residual Heat Removal (RHR) pump (B), which was active, after setting up the
SHC systems, they injected the water to the core & achieved cold shutdown.

87
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Fukushima Dai-ni Unit 4…Chronology

Chronology of Fukushima Dai-ni Unit 4 (Before earthquake: regular operation)
Events
3/11 14:46
Emergency
shutdown of
the reactor

Earthquake occurred (Level 6+)(M9.0. 4th in recorded history）● 14：46 Reactor automatically shutdown. All control rods inserted.
Main turbines automatically shut down. Core water level was low (L-3). 1
transmission system (500kV) stopped. External power secured withremaining 1 system.
● 15:05 Core sub criticality confirmed.
15:22

Loss ofemergency
equipments
by tsunami・・Started core
3/12
cooling.

0:16
7:23
7:35
11:17
11:44
11:52
13:48

RCIC automatically stopped (due to drop in core pressure drop).
Started water injection to the core by MUWC begun.
Started S/C cooling by FCS cooling system (MUWP).
Conducted S/C spray by MUWC.
Switched water injection to the core from MUWC to HPCS.
Started to construct PCV pressure resistance vent line.
Construction of the line above completed.
Stopped core water injection by HPCS (hereafter, conducted as needed).

11:00
13:07
14:56
15:42
16:02
18:58

EECW(B) manually activated (powered from power supply vehicle).
RHRS(D) pump manually activated (powered through makeshift cable).
RHRC(B) pump manually activated (powered through makeshift cable).
RHR(B) manually activated (S/C cooling mode begun).
RHR(B) S/C spray mode begun
Injected water to the core with RHR(B)LPCI mode.

3/14

Cold
shutdown.

●

Tsunami hit

Depressurized
RPV.

Restored
power
supply &emergency
equipments.

・(Tsunami-M9.1. 4th in recorded history)(Immersion height: 12~ 14.5m)

15:33 Water circulation pump (C) manually stopped
15:34 Emergency DG (A)(B)(H) automatically started => DG (A)(B) stopped
immediately due to tsunami.
15:35 Water circulation pumps (A)(B) automatically stopped.
15:36 All MSIV manually closed. RHR (B) manually activated => 15:41
automatically stopped.
15:37 RHR (A) manually activated => 15:38 manually stopped.
15:46 Core depressurization begun by SRV & pressure adjustment continued
henceforth.
15:54 RCIC manually activated (Water injection to core) & continued.
● 19:02 Warning of ‘dry-well (D/W) pressure is high’. => Automatic
activation signal for ECCS pump transmitted.
=>
As RHRC(A,B,C,D), RHRS(A,B,C,D) & EECW(A,B) pumps were not
usable, they switched off the automatic activation function of the ECCS
pumps in advance.
19:14 D/W cooling system automatically activated.

Maintainedcorepressure &water level.

Implications
●
・

3/15

●
・

・
・

●
・

・

●
・
・

●
・

・

Nuclear reactor automatically shutdown due to earthquake
The reactor reacted (scrammed) to earthquake in accordance with the design. No major
problems found.
Since external power survived, normal/emergency power source were secured.
Due to submergence by Tsunami, emergency power & sea water pump systems
were lost.
As the seawater heat exchange building was submerged, its emergency power systems (P/C)
became unavailable.
Emergency DG were active after core scram. However, emergency DG (A, B) were lost, since
all the Emergency Equipment Cooling Water (EECW) pumps were lost their functions. Since
emergency DG (H) was active, power source for core cooling was secured.
Maintained core pressure & water level with SRV and RCIC.
Regarding reactor pressure control, since water condenser was unusable because of the loss ofwater circulation pump (main steam could not be condensed), they closed all MSIV anddepressurized the core by SRV (as defined in the AM manual).
With all MSIV closed, they manually activated RCIC to inject water to the core.
As the core pressure dropped by SRV, RCIC stopped automatically. Then they changed towater injection by MUWC, following the AM manual.
Warning of high pressure in Dry Well.
Warning was alerted as D/W pressure rose very high. This is because SRV was opened (i.e.
main steam flew into S/C from core) and the loss of RHR (i.e. PCV residual heat could not be
removed).
Automatic activation signal for ECCS pump was transmitted because of high pressure in D/W.
As the EECW pumps were lost, they had switched off its automatic activation function
beforehand.
Prepared to cool S/C & D/W of PCV as well as ventilation.
For S/C cooling, they injected water to S/C through drain line from FCS cooling device, andsprayed water on to S/C by MUWC periodically.
Though they had structured the pressure resistance vent line to prepare for the rise in PCV
pressure, it had not reached to 310 kPa (= maximum designed pressure of PCV).
Achieved cold shutdown with the recovery of emergency cooling pump systems.
They recovered cooling system of RHR with makeshift cables, connected to the emergency
power system in the seawater heat exchange building at Unit 3, as well as recovered coolingsystem of emergency DG with high voltage power supply vehicles. With RHR (B) activatedmanually, they started S/C cooling.
Using LPCI line of RHR (B) system and SRV, they cooled the core with the heat exchanger of
RHR and achieved cold shutdown.
88

7:15 Cold shutdown achieved.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other
OtherPlants
Plants(Onagawa,(Onagawa,Tokai
TokaiDai-ni
Dai-niPowerPowerPlant)
Plant)
Chronologies
ChronologiesandandIssues
Issues89
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Overview of Earthquake

Extremely Confidential

Location of earthquake and power plants are as below. The earthquake was aroundlevel 6 in all locations. Some locations in Dai-ichi and Onagawa have exceeded “Ss*”.
(*: Ss = Standard seismic movement)

Tohoku Area Pacific Coast Earthquake: Data & Scale
Border line ofintensity 5● In terms of the distance from epicenter,
Onagawa power plant is the closest.
Following in order are Fukushima Dai-ichi,
March 11 , 2011
14:46, 24 km, M9.0
Dai-ni, and Tokai Dai-ni.

March 11th, 201115:08, 1 km, M7.5

Onagawa Plant

th

Epicenter

March 11th, 2011

Fukushima Dai-ichi& Dai-ni Plant

15:25, 34 km, M7.4

March 11th, 2011
15:15, 28 km, M7.3

Tokai Dai-ni Plant

Seismic Intensity

Fukushima Dai-ichi Fukushima Dai-ni

Seismic
Intensity

Maximum
Acceleration

Onagawa

Tokai Dai-ni

6+

6+

6-

6-

(Ohkuma town,
Futaba town)(Taruha town,
Tomioka town)(Onagawa town)(Tokai town)

550 gal

305 gal(East-west, Unit 2)(Vertical, Unit 1)

Some periodic
Comparison toband had
Ss
exceeded Ss.

● Regarding the seismic intensity, all plants
have recorded around level 6, and there are no
major differences.

Below Ss.

607 gal(South-north, Unit
2)

Some periodic
band hadexceeded Ss.
(March 11 & aftershockin April 7)

225 gal(East-west)

Below Ss.

● Maximum acceleration of seismic motion at
nuclear reactors: Onagawa was the largest
with 607 gal. Followed by Fukushima Daiichi (500 gal). The smallest was Tokai Dai-ni(225 gal).
● Standard seismic movement (Ss): Somelocations in Onagawa and Dai-ichi had
exceeded Ss.
- In some places at Onagawa, Ss were
exceeded even in aftershocks of April 7th.

90
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Facility Damage by Earthquake

Damage of important facilities for reactor safety has not been found with this earthquake,but the fatal accident and damage did happen at some other facilities. At Onagawa, a fireat Unit 1 and shutdown of external access were reported.
< Major damage of facilities reported >Damage of facilities

Other damage

Fukushima
Dai-ichi・ Unit 1: Air conditioning duct damaged.
・ Unit 2: Leak of non-radioactive steam from electric boiler.
・ Unit 5: Supports for moisture separator came off. Small-diameter pipe around the separator
ruptured.
・ Unit 6: Slide vestiges on low pressure turbine rotor.
・ Fire protection pipe of transformer damaged. Water leakage from the connection pipe of purewater tank.
・ Pumps & electrical boards for outside facilities damaged due to tsunami.

・ No problem with access road that had been
reinforced.
・ Heavy fuel oil tank and crane were drifted bytsunami, and blocked transportation.

Fukushima
Dai-ni・・・・・

4 cases of water leakage by sloshing (2 cases at unit 1, 2 cases at unit 2).
Unit 3: Overflow leakage of surge tank (Reactor building). 1 case.
Unit 4: Leak in turbine building.
1 case of oil leak from electric transformer.
Fatal accident of the tower crane operator during anti-seismic construction at main
exhaust stack.
・ 1 case of water leakage due to on-site bunker sloshing.
・ Unit 4: Crack of mother line of support leg’s connection duct in the main exhaust duct forventilation & air conditioning system.

・ No problem with access road.

Onagawa・ Unit 1: Collapse of heavy fuel tank (tsunami). Fire from regular M/C (Regulatory accident
reports: 4 cases).
・ Light damage to main facilities: 61 cases
・ Light damage to non-major facilities that did not affect the core safety (565 cases): Falling of
foreign material into SFP, and tumbling of drum cans with miscellaneous radioactive solid
waste, etc.

・ With 3 access roads to the plant, there was 1 placethat causes a bottleneck, and landslide occurred
there.
・ Took 4 days to recover with heavymachineries.
・ Due to a lack of food for 4 days, food wasbrought in by helicopter (researched by plant
operator).

Tokai Dai-ni

・ Automatic stoppage of DGSW (SC), stream overflow in 125V battery room (Regulatory
accident reports: 2 cases).
・ 139 cases of light damage ( sloshing of spent fuel pool, etc)

・ No problem with access road.

91
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Power Loss…

Extremely Confidential

Loss of power: External power was so vulnerable to earthquakes that all but two lines, each at Dai-ni
and Onagawa, were lost. Even one power source had made a life-or-death difference in accident
progression between Fukushima Dai-ichi and others, whether it was external or emergency.

● External power source isvulnerable to earthquake.
・ Not only Dai-ichi, but otherplants had lost almost all
external power.
● Even one emergency DG
made a huge difference.
・ Dai-ichi had lost all external andemergency power except for one
DG at Unit 6, and lost corecooling function.
・ Other plants had achieved cold
shutdown as at least one ofeither external or emergency
power survived.
● Emergency DG at Dai-ichi isespecially vulnerable.
・ At Dai-ichi emergency DG for
Units 1-4 are located on the sea
side (of TB building), and their
cooling systems were placedoutside on the coast.
・ Because of the location, allfunctions were lost due totsunami.

Fukushima Dai-ichi

Fukushima
Dai-niOnagawa

Tokai Dai-ni

Status of Dai-ni,
Onagawa, &Tokai Dai-ni

ExternalPower

All lost.
(of 6 lines)

1 line active.
(of 4 lines)

1 line active.
(of 5 lines)

All lost.
(of 3 lines)

Emergency
DG

Unit 1-5: all lost.
Unit 6:
OK (1 unit. Air cooling).
Lost (2 units. Water cooling).

Unit 1: all lost.
Unit 2: all lost.
Unit 3: 2/3 OK.
Unit 4: 1/3 OK.

Unit 1: all OK.
Unit 2: 1/3 OK.
Unit 3: all OK.

2/3 OK.

AC power (oremergency DG) was
active. => Core
cooling was possible.

(Location)

Turbine Building(Sea side)

Reactor Building(Mountain side)

Reactor Building(Mountain side)

Reactor Building(Mountain side)

Emergency DG was
located in the reactor
building.

Seawater
Pump
SystemAll submerged.

Partially
submerged.

Partially
submerged.

Partially
submerged.

Some seawater
pumps survived.

Outside of the building.

In the building.

In the building(partiallyoutside).

Outside of thebuilding.

No big difference.
(Tsunami height at
Dai-ichi was huge.)

Power supply vehicle.

Power supply
vehicles (partiallyused).

As external power or emergency DG survived, power supply
vehicles were not necessary.

(Location)

Equipments
procured for
power supply(Couldn’t use due to
Tsunami & explosions)

Looking at an overview of power loss at other plants, they were not particularly safer than Dai92
ichi, and faced the same risk of the extreme accident as Dai-ichi.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Onagawa… External Power

Extremely Confidential

Damage to external power: 4 out of 5 external power lines were lost due to the damage
to switching and transformer substations by the earthquake. On-site star-up transformer
was also damaged.
Transmission
Transmissionfrom
fromtransformer
transformerstations
stations=>=>44out
outofof55lines
lineslost
lostdueduetotoearthquake
earthquake● Ishinomaki transformer station, Onagawa● Ishinomaki transformer station, Onagawa
transformer station, & Miyagi Central switchingtransformer station, & Miyagi Central switchingstation had system accidents due to strong
station had system accidents due to strong
earthquake.
earthquake.
(= accident of system protection line by the transmission

Onagawa transformer station
Ishinomaki transformer station

Onagawa Nuclear Power Plant
Tsukahama line

Ojika main line(= accident of system protection line by the transmission
accident of Tohoku Electric Power Company)
accident of Tohoku Electric Power Company)

Unit 3
Activation transformer

Of 4 lines in 2 systems,
1 line stopped & 1 line
worked.
Miyagi Central switching station● Tsukahama main line (66kV1): Stopped.
● Tsukahama main line (66kV1): Stopped.
● Oshika main line (275kV) (2 lines): Both Stopped.
● Oshika main line (275kV) (2 lines): Both Stopped.
● Matsushima main line (275kV) (2 lines): Unit 1● Matsushima main line (275kV) (2 lines): Unit 1
stopped. Unit 2 survived.
stopped. Unit 2 survived.

Switching station△
Matsushima main line

Activation transformer broken.

Back-up transformer

Unit 2
Unit 1

Overview of major facilities, Tohoku Electric Power Company (HP)

Status of nuclear power plant after earthquake (1st report) (March, 11, 2011 Tohoku Onagawa Nuclear Power Plant)

On-site incoming facility => Activation
On-site incoming facility => Activationtransformer at Unit 1 malfunctioned.
transformer at Unit 1 malfunctioned.
● On-site incoming facility: Activation transformer● On-site incoming facility: Activation transformerof Unit 1 tripped, and unable to receive power.
of Unit 1 tripped, and unable to receive power.
(= Due to short circuit earth fault caused by(= Due to short circuit earth fault caused byearthquake).
earthquake).
● The activation transformer was recovered on● The activationtransformer was recovered on
March 12th.thThe plant had switched to receive theMarch 12 . The plant had switched to receive theregular external power (275kV1).
regular external power (275kV1).

93
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Onagawa Unit 1… Chronology

Chronology of Onagawa Nuclear Power Plant Unit 1 (Before earthquake: regular operation)
Events

3/11 14:46

Implications

Earthquake occurred (Level 6-)●(M9.0. 4th in recorded history）
Emergency
shutdown of
the reactor● 14:46 Due to the vertical earthquake acceleration, the reactor
automatically shut down.
14:47 All control rods were fully inserted. Automatic shutdown of main turbine.
Reactor water level was low (L-3).
Emergency DG (A)(B) automatically activated (non-loaded operation).
FPC pump (A) automatically stopped.
Water circulation pump (B), condenser pump (B), & reactor water supply
pump (A) were all automatically stopped.
14:55 Transformer for activation was damaged and stopped (due to excess relay
current).
Emergency DG (A), (B) begun.
Water circulation pump (A), condensing pump (C), nuclear reactor watersupply pump (B), turbine-driven auxiliary seawater cooling pump (A,C)
were all automatically stopped (power outage).

Electrical board
caught fire due
to earthquake.
External power
lost.
Emergency DG
activated● 14:57 Fire alarm generated
14:59 RCIC manually activated.
15:00~01 RHR pump (A) (C) manually activated. => Cooling of S/C begun.
15:02 All MSIV closed manually (as water condenser was unusable).
● 15：05 Sub criticality of reactor confirmed.
15:05~12 RHR pump (B) (D) manually activated. => Cooling of S/C begun.

15:29

No problem with seawater
pump system for cooling.

・

・
・

・
・
・

●
・
・
・

17:10 Core de-pressurization begun by SRVCore depressurization.

・

Maintainedcore waterlevel.
Cold shutdown
withemergency LP
pump.

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 13m)

・

18:29 RCIC pump automatically stopped (core water level high (L-8) ).
19:30~ FPC pump A manually activated (for SFP cooling).
20:20 CRD pump A manually activated (for water supply to reactor).
21:56 RHR pump A manually stopped (to prepare for shutdown cooling (SHC)).
23:46 RHR pump A manually activated (SHC mode).

3/12

●
・

As external power was lost due to earthquake, emergency DG started
to generate power.
The nuclear reactor behaved (scrammed) after earthquake in accordance with thedesign. No major problems found.
Due to loss of regular power, all pumps for water supply & condenser system were
stopped. Following the AM manual, they activated RCIC and secured the watersupply to the core.
Emergency DG was activated by the low voltage generated when the external
power supply was switched from regular line to back-up line within the plant.
It is assumed that a fire alarm was on by the arc discharge, due to the short circuit& earth fault occurred when regular power supply system was damaged by theearthquake.
As the over-current relay of activation transformer was activated by the fire, thetransformer was tripped. This trip activated the emergency DG.
As the condenser pump was lost, they closed MSIV and de-pressurized the core, in
accordance with the AM manual.
FPC pump (A) was automatically stopped, because the level switch for ‘skimmer
surge tank’ was activated by the seismic motion, or the intake pressure of SFP
pump dropped when the water level in the pool went down temporarily bysloshing.
Core depressurization by Safety Relief Valve (SRV).
They opened SRV and released the steam to S/C.
After RCIC pump was stopped, they supplied water to the core by CRD pump.
Regarding core cooling operation, it was done by RHR system in accordance with
the AM manual. No problems found.
Having inspected the FPC pump (A) after earthquake and confirmed as normal,
they re-activated the FPC and started cooling the SFP. During this stop of FPC,
there was no significant rise in water temperature of the pool.
Cold shutdown achieved.
With RHR system, cold shutdown was achieved.

0:58 Cold shutdown achieved

94
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Onagawa Unit 2… Chronology

Extremely Confidential

Chronology of Onagawa Unit 2 (The plant was under 11 regular inspection and had been activated just before the earthquake.)th

Events

Implications

3/11 14:00 Started to pulling out the fuel rods.
●
14:46

Emergency
shutdown of
the reactor

Earthquake occurred (Level 6-)(M9.0. 4th in recorded history）

・● 14:46 Nuclear reactor automatically shut down due to thehorizontal acceleration of seismic motion.

・

14:47 All control rods were inserted.
Emergency DG (A) (B)(H) automatically activated.
FPC pump (B) automatically stopped.

・・
14:49 Reactor mode switch was changed from ‘activated’ to ‘stopped’.
(shutdown cooling).
15:29

2 seawater
pumps & 2
DG werelost due totsunami.

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 13m)

15:34 RCW pump (B)(D) automatically stopped (as the pump submerged).
15:35 Emergency DG (B) automatically stopped (as RCW pump stopped).
15:41 HPCW pump automatically stopped (as the pump submerged).
15:35 Emergency DG (H) automatically stopped (as HPCW pump stopped). ・
20:29 FPC pump (A) manually activated (to cool SFP).
3/12

Maintained
shutdown
cooling modewith 1 sea
water pump &
1 DG.

●
・

As the earthquake occurred when the reactor was being activated, it
was already in shutdown cooling condition.
The nuclear reactor behaved (scrammed) after earthquake in accordance with thedesign. No major problems found.
As the reactor was under sub-critical condition with water temperature below100℃
at the time of earthquake, ‘shutdown cooling’ status was brought about by modeswitching.
As the generator signaled for ‘magnetic loss’ due to the seismic motion, emergency
DG(A) (B) (H) were automatically activated and became standby condition without
power generation.
FPC pump was automatically stopped, because the level switch for ‘skimmer surge
tank’ was activated by the seismic motion, or the intake pressure of SFP pump
dropped when the water level in the pool went down temporarily by sloshing.
Due to submergence from tsunami, RCW pump (B) was stopped.
The sea water flowed into the reactor building, through the penetration of the water
gauge for automatic stop of circulation pump in the seawater pump room. Due tothis flooding, RCW (B,D) pump and HPCW pump were disabled. As the coolant
water was lost due to this stoppage, emergency DG (B) (H) were automaticallyhalted.
As RCW(A) system was sound, emergency DG (A) continued to operate and thereactor cooling function was secured. The cooling function of SFP was also secured
by FPC pump (A).

4:49 Reset the nuclear reactor scram.
12:12 RHR pump (A) manually activated (SHC mode)=> shutdown cooling maintained.

95
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Onagawa Unit 3… Chronology

Chronology of Onagawa Unit 3 (Before earthquake: regular operation)
Events

3/11 14:46

Earthquake occurred (Level 6-)(M9.0. 4th in recorded history）

Emergency
shutdown of
the reactor● 14:46 Nuclear reactor automatically stopped due tovertical acceleration of seismic motion.
14:47 All control rods were inserted. Main turbines automatically
stopped. FPC pump (B) automatically stopped.
● 14:57 Core sub criticality confirmed.
15:22 Turbine building closed cooling water system (TSW) pump (A,C)
automatically stopped (as pump submerged).
15:23 Water circulation pump (A, B) automatically stopped.
FPC pump (A) manually activated.
15:25 MD-RFP (A,B), HPCP (A,B) manually stopped (as all TSW
stopped).
15:26 Closed MSIV manually (as condenser being unusable).
RCIC manually activated (to supply water to reactor).
15:28 RSW pump (D) manually activated. => Cooling of S/C.

Turbinedriven
coolingsystem lostby Tsunami.
Started RCIC
cooling.

Implications

●
・
・
・

●
・

・

Tsunami hit
15:29(Tsunami-M9.1. 4th in recorded history)(Immersion height: 13m)

15:30 RCW pump (B) manually activated. => Cooling of S/C.
RHR(B) manually activated => Cooling of S/C.
15:36 Vacuum break of condenser (as condenser being unusable).
15:43 RSW pump (C) manually activated. => Cooling of S/C.
15:44 RHR(A) manually activated. => Cooling of S/C.
15:45 RCW pump (A) manually activated => Cooling of S/C.
Core depressurization.

16:40~ Started core depressurization by SRV

Maintainedcore waterlevel.

●
・

・
・

●
・

Nuclear reactor automatically shutdown due to earthquake.
The nuclear reactor behaved (scrammed) after earthquake in accordance withthe design. No major problems found.
Both regular power & all emergency DG were secured.
FPC pump was automatically stopped, because the level switch for ‘skimmer
surge tank’ was activated by the seismic motion, or the intake pressure of SFP
pump dropped when the water level in the pool went down temporarily bysloshing.
As seawater pump for turbine cooling was lost by Tsunami, coolant
water was supplied by RCIC.
As the signal for extremely low water level in the seawater pump room was
generated, water circulation pump stopped. Furthermore, seawater flooded into
the seawater pump room of heat exchanger building, causing TSW pump tostop.
As the coolant water supply was gone, they manually activated RCIC andcontinued to supply water to the core.
Core depressurization by safety relief valve.
As condenser became unusable due to stoppage of water circulator pump,following the AM manual, they closed all MSIV and depressurized the core by
SRV.
After RCIC pump was stopped, they supplied water to the core, using make-up
water system (MUWC).
They activated residual heat removal (RHR) system manually, and started
cooling with SHC mode.
Cold shutdown achieved.
With RHR system operation, cold shutdown was achieved.

16:40 RCIC pump stopped (core water level (L-8)).
16:57 RCIC manually activated (water supply to the core).
21:44 RHR pump A manually stopped (to prepare for SHC (flushing)).
21:45 RCIC manually stopped.
21:54 Water injection to the core by MUWC.
23:51 RHR pump (A) manually started (SHC mode).

Cold shutdown
withemergency LP
pump.

3/12

1:17 Cold shutdown achieved.

96
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Tokai Dai-ni… External Power

Extremely Confidential

Damage to external power: As Naka and Ibaraki transformer stations stopped by strong
seismic motion, all the external power was lost. Insulating oil was leaked fromtransformer in the plant.

Leakage of insulating oil from main &activation transformers.

Transmission
Transmissionfrom
fromtransformer
transformerstation
station=>=>All
Allstopped
stoppeddue
duetotoearthquake.
earthquake.

To Shin Iwaki switching station, Shin Fukushima transformer station.

Shin Mogi transformer station

Stopped by earthquake.
(Recovered by March 15)

Naka transformer station

Tokai Dai-ni Nuclear
Power Plant●● As
AsNahaNahaandandIbaraki
Ibarakitransformer
transformerstations
stations
werestoppeddue
tostrongseismic
were stopped due to strong seismicmotion,
motion,allthetransmission
lines
were
stopped.
all the transmission lines were stopped.

High voltage
switching station
Activation transformer

Stopped by earthquake.
(Recovered by March 15)

Back-up transformer
Tokai Power Plant switching station
Stopped by earthquake.
(Recovered by March 15)

Back-up external
power recovered, in
19:37, March 13th.
Ibaraki transformer station
Matsumura line

Shin Furukawa transformer station
Kasumigaura transformer station

Tokai Dai-ni Nuclear Power Plant, application for construction permission.
Nuclear Safety Committee, ‘Report of power company on fire protection at nuclear power plant in case of earthquake’.

Incoming
Incomingfacilities
facilitieson-site
on-site=> Insulation oil leaked frommain &=> Insulation oil leaked from main &activation
activationtransformer
transformer
●● Of
Ofthe
theincoming
incomingpower
powerfacilities,
facilities,insulating
insulatingoiloilwaswasleaked
leakedfrom
frommainmaintransformer
transformerandandactivationtransformer.
activation transformer.
th: External backup power●● On
OnMarchMarch1313th: External backup power(154kV,
11line)(154kV,11system,
system,line)waswasrecovered.
recovered.
th●● On
OnMarchMarch18
18th: :Switched
Switchedtotoexternal
externalregular
regularpower
line(275kV,1system1line),
andpower line (275kV, 1 system 1 line), andregularregularpower
powersystems
systemsrecovered.
recovered.

97
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Tokai Dai-ni… Chronology

Extremely Confidential

Chronology of Tokai Dai-ni (Before earthquake: regular operation)
EventsEmergency
shutdown of
the reactor

3/11 14:46

Earthquake occurred (Level 6-)(M9.0. 4th in recorded history）● 14：48 Nuclear reactor automatically stopped due to turbine trip
(large seismic motion).
● All external power lost => Emergency DG automatically activated. =>Emergency power secured.
RCIC & HPCS automatically activated => then stopped (water level =high).
15:01 RHR pump (A) activated. => Cooling of S/C begun.
● 15：10 Core sub criticality confirmed.

1 emergency
DG lost due
to tsunami

15:32

Tsunami hit(Tsunami-M9.1. 4th in recorded history)(Immersion height: 3m)

15:36 Started maintaining water level by RCIC.
16:40 RHR pump (B) activated. => Cooling of S/C begun.
● 19:01 Seawater pump for emergency DG stopped automatically.
19:21 RHR pump (A), RHRS pump (A,C) stopped.
19:25 Emergency DG (2C) stopped. => Main emergency power line (2C) lost.

Transition to
cold shutdown
through core 3/12
depressurizati
on & RHR.

3/13

3/14

3/15

Recoveryofexternal
power.

21:52 Started core depressurization by SRV
13:11 RCIC pump manually stopped. => Switched to HPCS for maintaining
core water level.
● 19:37 Backup external power recovered. => Incoming power toemergency main line (2C) recovered.
3:50 RHR pump A started. => Cooling of S/C begun.
23:43 RHR pump A started. => Started shutdown cooling mode (core watertemperature: 117℃).

0:40 Cold shutdown achieved.
(core water temperature: 99.8℃. Core pressure: atmospheric pressure)
2:26 RHR pump B stopped. => Cooling of S/C stopped.
2:49 Emergency DG (2D) stopped.
4:09 HPCS pump stopped.
4:19 DG for HPCS system stopped.

3/17● 15:47 Regular external power recovered. => switched frombackup power.

Implications

●
・
・

●
・

・

・

・

●
・
・
・
・

●
・

All external power was lost due to earthquake.
The nuclear reactor behaved (scrammed) after earthquake in accordance with thedesign. No major problems found.
Automatic startup of emergency DG by the scram was in accordance with thedesign, and the emergency power was secured.
1 emergency DG system was lost due to submergence of tsunami.
With tsunami re-evaluation on Sumatra Earthquake (March, 2007), the assumed
height of tsunami was raised by 1m. Following this, the safety measure to seawater
pump for emergency DG was raised to 6.11m from 4.91m.
The tsunami did not reach the newly erected floodgate, but flooded into the gate
through a ground cable tray that was being dug for fortification, then flowed into
the seawater pump pit. The pit was submerged up to 2m, and 2 seawater pumps for
emergency DG located below, were totally submerged, and stopped.
Because of that, emergency DG (2C) was stopped manually. The emergency DG(2D) and DG for HPCS system was working and power was secured. However, if
all 3 seawater pumps for DG were submerged, the entire power source could havebeen lost, as all the external power had been already lost by earthquake.
Underground cable pit that had been submerged goes through the newly erectedfloodgate. Normally it is sealed and a tsunami of this height would not have flooded
into the gate.
Core depressurization by safety relief valve (SRV).
They opened SRV for core depressurization, and the steam was released into the
suppression chamber (S/C).
They stopped RCIC pump manually, and transitioned to water level adjustment
with HPCS.
After that, as backup external power was recovered, the emergency main line (2C),
that had been lost due to the loss of DG, started receiving power again.
With incoming power to emergency main line 2C, the RHR system was started
manually to cool the reactor.
Cold shutdown achieved.
With recovery of RHR system, cold shutdown had been achieved within a short
time.

98
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Other Plants… Onagawa, Higashi-Dori, Tokai Dai-ni… Power System

Extremely Confidential

Loss of power other than external power: Compared to Dai-ichi, the loss of emergency
DG, electrical panels & DC power were less serious in Onagawa, Higashi-Dori, & Tokai
Dai-ni, where the submergence was small. This had become a lifeline.
Loss of electrical facilities & sea water systems after tsunami

99: Lost functions: Unable to activate due to electrical board and/or cooling system were lost
: Incoming power was inaccessible due to the loss of electrical supply source

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Onagawa, Higashi-Dori, Tokai Dai-ni… Cooling System

Loss of cooling function: Compared to Dai-ichi, functions of water injection to the coreand cooling worked normally in other plants as at least one AC/DC power and sea watercooling system functioned.
● Loss of DC power was fatal.
・ At Dai-ichi, as DC power was
submerged or depleted, they could
hardly inject water to the core.
・ As a result, they could not conduct
AM operations (high pressure cooling,
depressurization, low pressure
cooling).
・ If DC batteries had not been
submerged, they could have recharged
the batteries from AC power.

● Damage of sea side (seawater cooling system) bytsunami.
・ At Dai-ichi, the tsunami damage on
the sea side was so enormous thatthe functions of the sea water
pumps and emergency pumps werecompletely lost.
・ The damage at other plants was
small.

Fukushima
Dai-ichiFukushima
Dai-niOnagawaTokai
Dai-niComment on
Dai-ni,Onagawa &Tokai Dai-ni

Water
Injection toCore

Though all AC power was lost, DC
power partially survived in units 2& 3, and the high pressure cooling(RCIC) was continued for a while. It
stopped when batteries run out. The
system line for low pressure cooling
could not be reconstructed in time.

While RCIC and high pressure spraysystems were working, they could set
up the system line for low pressure
cooling and maintain the core waterlevel.

Water injection
to the core hadfunctioned.

Removal of
Decay Heat

With no AC power and loss ofauxiliary sea water systems by
Tsunami, they could not release thedecay heat to the ocean.

As the residual heat removal system(RHR) partially functioned, they could
cool the core and release the decay
heat to the ocean.

Seawater coolingand pump systems
had functioned.

Pure water (on-site)

They could supply
water from theexisting source.

Cooling
Water
SourcePure water (on-site) and sea water.

Equipments
Preparedfor Water
SupplyPump vehicle, makeshift hose(Took much time to connect).

Since AC power and core cooling systems had survived, it
was not necessary to procure additional pumps for water
injection.

100
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Other Plants… Cold Shutdown

Process to cold shutdown: Since AC power (external or emergency DG), DC power, and seawatercooling functions were active at other plants, cold shutdown was achieved. At Fukushima
Dai-ichi, these were all lost simultaneously.
Form

External AC power
DC power (A),(B)
Emergency DG
Sea water system
2011/3/11

Fukushima Dai-ni
Unit 1
Mark 2(BWR-5)

Fukushima Dai-ni
Unit 2
Improved Mark 2(BWR-5)

Fukushima Dai-ni
Unit 3
Improved Mark 2(BWR-5)

Fukushima Dai-ni
Unit 4
Improved Mark 2(BWR-5)

Onagawa
Unit 1
Mark 1(BWR-4)

Onagawa
Unit 2
Improved Mark 1(BWR-5)
Under regularinspection, but activatedjust before theOnagawa
Unit 3
Improved Mark 1(BWR-5)Tokai Dai-ni
Unit 2
Mark 2(BWR-5)In operation

In operation

In operation

In operation

In operation

In operation

In operation○(1/4 lines)○(2 systems)○(1/4 lines)○(2 systems)

×
×

×
×

○(1/4 lines)○(2 systems)○(2/3 units)○(2/3 systems)○(1/4 lines)○(2 systems)○(1/3 units)○(1/3 systems)○(1/5 lines)○(2 systems)○(2/2 units)○(2/2 systems)○(1/5 lines)○(2 systems)○(1/3 units)○(1/3 systems)○(1/5 lines)○(2 systems)○(3/3 units)○(3/3 systems)○(2 systems)○(2/3 units)○(2/3 systems)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Scram

Scram

Scram

Scram

Scram

Scram (Shutdown cooling)

Scram

Scram

×

Fire started (Arc discharge inregular electrical panel 14:57)

RCIC manuallyactivated (15:26)
RCIC manuallyactivated (14:59)
Tsunami hit (1st wave：15:22)

Tsunami hit (1st wave：15:22)

Tsunami hit (1st wave：15:22)

Tsunami hit (1st wave：15:22)

Tsunami hit (around 15:29
Tide indicator at maximum
water level)

RCIC activated(15:36)

Core depressurized(SRV operation 15:41)

Core depressurized(SRV operation 15:46)

Core depressurized(SRV operation 15:46)

Core depressurized(SRV operation 17:10)

Core depressurized(SRV operation 15:55)

RCIC activated(15:43)

RCIC activated(16:06)RCIC activated (15:54)

RCIC automatically stopped(18:29)D/W cooling system activated(17:53)D/W cooling system activated(20:02)

D/W cooling system activated(20:12)

D/W cooling system activated(19:14)

Spent fuel pool cooling (FPC
pump manually activated
19:30)

Tsunami hit (around 15:29
Tide indicator at maximum
water level)

Spent fuel pool cooling (FPC
pump manually activated
20:29)

Core depressurized(SRV operation
approx. 16:40)

Core depressurized(SRV operation 21:52)

RCIC manually stopped(21:45)
Water injection to nuclear
reactor begun (MUWC 21:54)

RHR pump manuallyactivated (SHC mode
23:46)RCIC manually stopped(23:11)

Tsunami hit (1st wave：15:32)

RCIC manuallyactivated (15:36)

Water injection to nuclear
reactor begun (CRD pumpmanually activated 20:20)

Water injection begun(MUWC system 22:53)

Tsunami hit (around 15:29
Tide indicator at maximum
water level)

RHR pump activated(SHC mode 23:51)

2011/3/12
Water injection begun(MUWC system 0:00)

2011/3/13

RHR manually activated (SHC
cooling mode 2:39)

RCIC automatically stopped(0:16)
Water injection begun (MUWC

Cold shutdown (0:58)

Nuclear reactor scram/reset(4:49)

Nuclear reactor rapid
depressurization begun (3:50)

Water injection begun(MUWC system 4:50)

RHR S/C spray mode begun(2:41)

S/C cooling (from MUWC to
FCS7:23)

RHR pump manuallyactivated (SHC mode
12:12)RCIC manually stopped (4:58)

RCIC manually stopped (4:53)

RHR manuallyactivated (SHC mode
begun 9:37)

S/C spray (MUWC system 7:35)

Cold shutdown
maintained (12:12～)

S/C cooling (MUWC from
FCS line 6:20)

S/C cooling (MUWP from
FCS line 6:30)

PCV pressure resistant ventline structure completed(12:13)

Water injection to nuclear
reactor (switch to HPCS 11:17)

S/C cooling stopped (MUWC
7:45)

S/C cooling stopped (MUWP
7:52)

Cold shutdown (12:15)

PCV pressure resistant vent line
structure complete(11:52)

PCV pressure resistant ventline structure completed(18:30)

PCV pressure resistant ventline structure completed(10:58)

Cold shutdown (1:17)

RCIC manually stopped(13:11)transition to HPCS

Nuclear reactor water injection
stopped (HPCS 13:48)

RHRS, RHRC pump activated(incoming power frommakeshift cable 20:17/21:03)

Supplemental external power
recovered (19:37)

2011/3/14
Emergency auxiliary coolingsystem activated (EECW.
Incoming power frommakeshift power 1:44)

Emergency auxiliary coolingsystem activated (EECW.
Incoming power frommakeshift power 3:20)

Water injection to
nuclear reactor begun(RHR LPCI mode
10:05)

Water injection to
nuclear reactor begun(RHR LPCI mode
10:48)

RHR pump activated (S/C poolcooling begun 3:50)

EECW manually activated(received power from supply
vehicle 11:00)

Water injection to
nuclear reactor begun(RHR LPCI mode
18:58)

Water injection to spent fuelpool begun (FPMUW system
16:30)

Cold shutdown (17:00)

RHR S/C spray mode begun(16:02)

Cold shutdown (18:00)
RHR pump activated(Shutdown coolingmode 23:43)

2011/3/15

Cold shutdown (7:15)

101

Cold shutdown (0:40)

2011/3/16
Switched to normal external
power (15:47)

2011/3/17

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Facts
FactsandandIssues
IssuesofofMajor
MajorFunctions
Functions・・Power
PowerSupply
Supply・・HighHighPressure
PressureCooling
CoolingSystem
System・・Ventilation
VentilationSystem
System・・Low
LowPressure
PressureCooling
CoolingSystem
System・・Hydrogen
HydrogenExplosion
Explosion

102
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons learned from Fukushima Dai-ichi…Design Philosophy…Power loss…

Extremely Confidential

Long-term power outage (DC&AC) had occurred, while design philosophy assumed “incase of Station Blackout, AC power would be quickly restored, and DC will last for at least
8 hours”.
Fukushima
Dai-ichiReactor 1

Fukushima
Dai-ichiReactor 2

Fukushima
Dai-ichiReactor 3

・
Restorationof external
power

Tokai Dai-ni

×All 6 lines were lost from the earthquake

Only 1/4 lines
workedOnly 1/5 lines
workedAll 2 lines lost fromthe earthquake△○
・ Reactor 1 & 3: allworking・ Reactor 2: 1/3
working×△

Lost all from the tsunami

Only 1/5 wasworking・ Reactors 1 & 2:
none worked
・ Reactor 3: 2/3
Reactor 4: 1/3
worked○4/4 working○
8/8 working○
Used to power
sea-line pump○
Power partiallyrestored by power
supply vehicle○
2/2 working

×
Lost all fromthe tsunami

×・

Onagawa
Reactors 1 - 3△

Lost all from the tsunamiPowersupplyvehicleFukushima Dai-ni
Reactors 1 – 4△

×

DC power
supplyFukushima Daiichi
Reactors 5&6

×External
AC power

Backupdieselgenerator

Fukushima
Dai-ichiReactor 4

Reactor 2: Planned to use the power supply vehicle but it wasdestroyed by explosion in Reactor 1.
Reactors 1, 3 and 4: Response was slow due to search for usable
power panels and installing of cables to the available power panels.

×
Not restored before the hydrogen explosion

×
Not restored
before cold
shutdown○
6/6 working○
2/2 working－
Not required since external power supply or
emergency generator was working.

－At least one external power source wasavailable right after the earthquake andTsunami.

Power loss lasted longer than expected in the design○
・ 2/3 working○
154kV backup
power restored on
March 13 at 19:37.

103

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons learned from Fukushima Dai-ichi…Design Philosophy…Cooling System…

Extremely Confidential

At Fukushima Dai-ichi Reactor 1, complete loss of all cooling systems, due to total power
loss, had rapidly led to core-meltdown. Core damage is estimated to have started 2 to 3
hours after Tsunami.
Loss of cooling system and occurrence of core meltdown
Dai-ichiReactor 1
HPCI /
HPCS

Dai-ichiReactor 2

Dai-ichiReactor 3

××

Malfunction

After DCpower
drainedHigh Pressure Cooling

IC /
RCIC

×

×

Worked but later
malfunctioned(Reactor 2: 3 days after)

After DCpower
drained

Dai-ichiReactor 4

Dai-ichiReactor 5&6－
In cold shutdown－
In cold shutdown

Fukushima
Dai-niOnagawa×Rctr 1&2:

×Rcr2

Flooded andlost.
○Rctr 3&4

○Rctr 1.3○

Fukushima Dai-ichi Reactor 1: Total loss of cooling function
Tokai
Dai-nicondensate watertransfer pumpDD fire pump○With fire truck

Filtered water tank○(to be verified)

海
condensate water tank

Alternative
water

Containment vessel
Pressure tank

Main Steam Release Safety Valve (SRV)
Driver air

SLC System

××Rctr 5Due to power loss

○Rctr 6××Rctr 5

CRD System○

D / W vent○(to be verified)Electro magnetic
valve

○

○
(to be verified)Containment
vessel vent

MO
(AC)

Exhaust pipe

Low Pressure CoolingFP×
FP pump not working

Driver air

Manual handle

Electro magnetic
valve○Rctr6

Due to power loss

××Rctr 5

Power loss

○Rctr 6

MO
MO
(DC)
(AC)
MO
MO
(DC)
(AC)

AO

○

△
(to be verified)

圧力抑制室 (S /C)

AO

Rapture disk

S / C ventMUWC /
MUWP

○
Power
supplied×Power supply and motor flooded

LPCS
seawater pump

CCSW / RSW/ RHRS etc.

Core damage start(Analysis)

×

△
RHR
partiallyfunctioned,
then restored

3 / 14
19:46

3 / 13
8:46

Hydrogen Explosion○(to be verified)

放水口へ
From
海 water inlet

Seawater cooling type power supply and motor flooded

3 / 11
18:46○

On halt
Reactor 4 hydrogen
explosion(Backflow from Rctr 3)△○
Partially flooded

Lost except
Rctr 3 (nopower &
motor)
Operating ＝＞ cold shutdown(or damage)Core was damaged a few hours after the loss of cooling
functions followed by exposure of fuel rods.

SHC pump

Supporting
saline pumpCore spraypump (CS)

ＩＣ

HPCI

● Dai-ichi Reactor 1: All cooling functions
were lost simultaneously.
● No other option but to supply water
to the104
reactor with only one fire truck.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons Learned from Fukushima Dai-ichi…Importance of power supplies…

Extremely Confidential

Even with such a strong earthquake and tsunami, cold-shutdown could have beenachieved if even a single emergency power supply were secured; Fukushima Dai-ichi(Rctrs 5 & 6), Tokai Dai-ni, Fukushima Dai-ni, etc.

These reactors lost almost all external power, but were able to achieve cold shutdown with thesurviving (one or two) emergency generators. (Note: Frontline (RHR pump) has to be working as well)
Fukushima Daiichi
Reactor 1

Fukushima
Dai-ichiReactor 2

Fukushima
Dai-ichiReactor 3

External AC
power supply

Emergency
generator

DC power
supply(A type, B type)

HPCS(IC/RCIC, etc.)

LPCS(MUWC/MUWP,
etc.)
LPCS seawater
pump(CCSW/RSW/R
HRS, etc.)

Fukushima
Dai-ichiReactor 4

Fukushima Daiichi
Reactors 5 & 6

Fukushima Dai-ni
Reactors 1 - 4

Onagawa
Reactors 1 - 3

Tokai Dai-ni

×

△

△

×

Lost all 6 lines from the earthquake

Only 1/4 lines
Working

Only 1/5 working

Both lines lost inearthquake○
・ Reactors 1 & 3: allworking・ Reactor 2: 1/3
working×△△

Lost all from the tsunami

Only 1/5
Working(flex)

・ Reactors 1 & 2: Noneworking
・ Rector 3: 2/3 working
・ Reactor 4: 1/3
working○
4/4 working○
８/８ working○
2/2 working

×
Lost all from the tsunami

×○
2/3 working○
6/6 working○
2/2 working

Lost all fromthe tsunami

××

Malfunctioned after a while

Stopped after
DC powerdrained－On halt○
Shared power
supply×Power outage

○

○

×

△

seawater power supply & motor flooded by tsunami

None working except
Reactor 3: (power &motor flooded)Core damage / Hydrogen explosion (or damage)○
All working except Onagawa Reactor 2○(Needs to be verified)○Partially flooded○
Partially flooded

105

Cold shutdown achieved
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons Learned from Fukushima Dai-ichi…Importance of power supplies…

Extremely Confidential(Continued…) Chronology to cold shutdown or hydrogen explosion.
Form

External AC power
DC power (A),(B)
Emergency DG
Sea water system
2011/3/11

Fukushima Dai-ichi
Unit 1
Mark 1(BWR-3)

Fukushima Dai-ichi
Unit 2
Mark 1(BWR-4)

Fukushima Dai-ichi
Unit 3
Mark 1(BWR-4)

Fukushima Dai-ichi
Unit 4
Mark 1(BWR-4)In operation

In operation

In operation

Stopped(Regular inspection)

×
×
×
×

×
×
×
×

×

Earthquake occurred (14:46)
Scram

×
×

×
×
×
×

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Scram

Scram

○(2 systems)

Fukushima Dai-ichi
Unit 5
Mark 1(BWR-4)
Stopped(Regular inspection.
Fuel loaded)

Fukushima Dai-ichi
Unit 6
Mark 2(BWR-5)
Stopped(Regular inspection.
Fuel loaded)

Fukushima Dai-ni
Unit 1
Mark 2(BWR-5)In operation

In operation

In operation

In operation

In operation

××○(1/4 lines)○(2 systems)○(1/4 lines)○(2 systems)

×

×
×

×
×

○(1/4 lines)○(2 systems)○(2/3 units)○(2/3 systems)○(1/4 lines)○(2 systems)○(1/3 units)○(1/3 systems)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Scram

Scram

Scram

Scram

○(2 systems)

××Earthquake occurred (14:46)○(2 systems)○(1/3 units)

Fukushima Dai-ni
Unit 2
Improved Mark 2(BWR-5)

Fukushima Dai-ni
Unit 3
Improved Mark 2(BWR-5)

Fukushima Dai-ni
Unit 4
Improved Mark 2(BWR-5)

Onagawa
Unit 1
Mark 1(BWR-4)

Onagawa
Unit 2
Improved Mark 1(BWR-5)
Under regularinspection, but activatedjust before theOnagawa
Unit 3
Improved Mark 1(BWR-5)Tokai Dai-ni
Unit 2
Mark 2(BWR-5)In operation

In operation○(1/5 lines)○(2 systems)○(2/2 units)○(2/2 systems)○(1/5 lines)○(2 systems)○(1/3 units)○(1/3 systems)○(1/5 lines)○(2 systems)○(3/3 units)○(3/3 systems)○(2 systems)○(2/3 units)○(2/3 systems)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Scram

Scram (Shutdown cooling)

Scram

Scram

×

Fire started (Arc discharge inregular electrical panel 14:57)

IC activated (14:52)

RCIC activated (14:50)/ stopped (15：28)

RCIC activated (15:05)/ stopped (15：25)

RCIC manuallyactivated (15:26)
RCIC manuallyactivated (14:59)
Tsunami hit (1st wave：15:22)

Tsunami hit (1st wave：15:22)

Tsunami hit (1st wave：15:22)

Tsunami hit (1st wave：15:22)

Tsunami hit (around 15:29
Tide indicator at maximum
water level)

RCIC activated(15:36)

Core depressurized(SRV operation 15:41)

Core depressurized(SRV operation 15:46)

Core depressurized(SRV operation 15:46)

Core depressurized(SRV operation 17:10)

Core damage begun(18:46). By simulation

Core depressurized(SRV operation 15:55)

RCIC activated(15:43)

RCIC activated(16:06)RCIC activated (15:54)

RCIC automatically stopped(18:29)Large quantity of hydrogengenerated/accumulated

D/W cooling system activated(17:53)D/W cooling system activated(20:02)

D/W cooling system activated(20:12)

D/W cooling system activated(19:14)

Spent fuel pool cooling (FPC
pump manually activated
19:30)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)RCIC activated (15:39)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)RCIC activated (16:03)

Tsunami hit (around 15:29
Tide indicator at maximum
water level)

Spent fuel pool cooling (FPC
pump manually activated
20:29)

Core depressurized(SRV operation
approx. 16:40)

Core depressurized(SRV operation 21:52)

RCIC manually stopped(21:45)
Water injection to nuclear
reactor begun (MUWC 21:54)

RHR pump manuallyactivated (SHC mode
23:46)RCIC manually stopped(23:11)

Tsunami hit (1st wave：15:32)

RCIC manuallyactivated (15:36)

Water injection to nuclear
reactor begun (CRD pumpmanually activated 20:20)

Water injection begun(MUWC system 22:53)

Tsunami hit (around 15:29
Tide indicator at maximum
water level)

RHR pump activated(SHC mode 23:51)

2011/3/12
D/W pressure rise(to 0.84MPa 2:30)

Hydrogen
explosion(15:36)

Electrical supply vehicle
damaged (15:36)

RHR manually activated (SHC
cooling mode 2:39)

RCIC automatically stopped(0:16)
Water injection begun (MUWC

Water injection begun(MUWC system 4:50)

RHR S/C spray mode begun(2:41)

S/C cooling (from MUWC to
FCS7:23)

RHR pump manuallyactivated (SHC mode
12:12)RCIC manually stopped (4:58)

RCIC manually stopped (4:53)

RHR manuallyactivated (SHC mode
begun 9:37)

S/C spray (MUWC system 7:35)

Cold shutdown
maintained (12:12～)

S/C cooling (MUWC from
FCS line 6:20)

S/C cooling (MUWP from
FCS line 6:30)

PCV pressure resistant ventline structure completed(12:13)

Water injection to nuclear
reactor (switch to HPCS 11:17)

S/C cooling stopped (MUWC
7:45)

S/C cooling stopped (MUWP
7:52)

Cold shutdown (12:15)

PCV pressure resistant vent line
structure complete(11:52)

PCV pressure resistant ventline structure completed(18:30)

PCV pressure resistant ventline structure completed(10:58)RCIC stopped (11:36)

SRV automatically opened(core pressure 8MPa maintained
1:40)

Water injection begun(MUWC system 0:00)

HPCI activated (12:35)

Top valve of reactor
pressure vessel opened (6:06)

Nuclear reactor rapid
depressurization begun (3:50)

Power supply begun from Unit
6 DG (DC recharge 8:13)

Power supply begun to Unit 5(DC recharge 8:13)

2011/3/13

Cold shutdown (0:58)

Nuclear reactor scram/reset(4:49)

Cold shutdown (1:17)

RCIC manually stopped(13:11)transition to HPCS

Nuclear reactor water injection
stopped (HPCS 13:48)

RHRS, RHRC pump activated(incoming power frommakeshift cable 20:17/21:03)

HPCI stopped (2:42)
Core exposure begun(Water level ＝TAF attained
4:15)

Core damage begun(around 8：46). By
simulation
Large quantity of hydrogengenerated/accumulated

Hydrogen back flew
(From Unit 3)

Nuclear reactor
depressurized (Releasesafety valve @ 9:08)
Fresh water injection from fire
trucks begun (with boric acid9:25)
Power supply begun from Unit
6 DG (MUWC system. 18:29)

SC vent AO valve (large
valve) opened (12:30)

Nuclear reactor water injection
begun (Make Up Water Pump
system. 13:20)

Supplemental external power
recovered (19:37)

2011/3/14
Fire trucks damaged (@11:01)

SC vent AO valve (small
valve) opened (5:20)

Core depressurized(SRV opened 5:00)

Loss of cooling function wasdetermined(RCIC stopped (@13:25))

Sea water supply begun fromstorage to reverse valve pit(9:20)

Water injection to nuclear
reactor begun(MUWC 5:30)

Core depressurized(SRV opened @18:00)

Self Defense Force water supply
vehicles arrive, supplied fresh
water from reverse valve pit(10:53)

Water supply to spent fuel pool
begun
(MUWC 9:27)

Fuel rods completely exposed(Water level＝TAF-3700mm
18:22)

Hydrogen explosion(11:01)

Emergency auxiliary coolingsystem activated (EECW.
Incoming power frommakeshift power 1:44)

Emergency auxiliary coolingsystem activated (EECW.
Incoming power frommakeshift power 3:20)

RHR pump activated (S/C poolcooling begun 3:50)

EECW manually activated(received power from supply
vehicle 11:00)

Water injection to
nuclear reactor begun(RHR LPCI mode
10:05)

Core damage begun(@19:46). By
simulation

Water injection to spent fuelpool begun (FPMUW system
16:30)

Large quantity of hydrogengenerated/accumulated

Cold shutdown (17:00)

Water injection to
nuclear reactor begun(RHR LPCI mode
10:48)

RHR S/C spray mode begun(16:02)

Water injection to
nuclear reactor begun(RHR LPCI mode
18:58)
Cold shutdown (18:00)
RHR pump activated(Shutdown coolingmode 23:43)

Sea water injection begun
by fire trucks (19:54)

2011/3/15

Pressure incontainment vessel S/C
indicated 0MPa (abs)(6:00-6:10)

Hydrogen explosion(6:12)

Cold shutdown (7:15)

Cold shutdown (0:40)

2011/3/16
Switched to normal external
power (15:47)

2011/3/17
2011/3/18
Passage to roof opened(3 spots 13:30)

Passage to roof opened(3 spots 17:00)

RHR makeshift sea water pumpactivated(emergency system 1:55)

RHR makeshift sea water pumpactivated(emergency system 21:26)

RHR manually activated (Fuelpool cooling @5:00)

RHR manually activated (Fuelpool cooling 22:14)

RHR pump activated(Shutdown-cooling mode
12:25)

RHR pump activated(Shutdown-cooling mode
18:48)

Cold shutdown (14:30)

Cold shutdown (19:27)

2011/3/19

2011/3/20

106
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons Learned from Fukushima Dai-ichi…Placement…

Extremely Confidential

Critical devices, such as emergency power supplies (AC) and batteries (DC), were stored inbasements and completely flooded.
● The greater the height difference between the tsunami and the altitude of the plant, the greater the damage=> Dai-ichi No 1-4: 5.5m, No 5, 6: 1.5m. Onagawa: 0m. Tokai Dai-ni: -2.6m● Those power supplies placed in areas much lower than the tsunami crest were disabled.
Dai-ichi Rctr1

Reactor 2

Height of flood

Reactor 3

Reactors 5 & 6

Fukushima Dai-ni

Onagawa

Tokai Dai-ni

O.P.aprx14.5m

O.P.aprx14.5m

O.P.aprx13m

H.P.6.3ｍ(T.P.= O.P.+0.727ｍ)(T.P.=O.P.+0.727ｍ)(T.P.=O.P.+0.74ｍ)(T.P.= H.P.0.89m)

O.P.13m

O.P.12m

O.P.13.8m

H.P.8.9m

O.P.1.9m(A)Reactor 5

O.P.0m

O.P.0.5m(No.1 A/B)

O.P.10.2m(B)O.P.4.9m(A)/(B)

H.P.1.6ｍ(A/B/H)(Air cool)

Reactor 6

O.P. 15.5m(Main building area)(T.P. =

Altitude (Mainbuilding)
Emergency
generator
elevation

Reactor 4

O.P.+0.727ｍ)

O.P.10m

O.P.4.9m(A)O.P.1.9m(A)O.P.2ｍ(B)O.P.10.2m(B)(Air cool)

O.P.1.9m(A/B)(No. 1～4 A/B/H)

O.P.14ｍ(No. 2/3 A/B/H)

O.P.5.8m(A)/(H)

13.2m(B)O.P.

(Air cool, survived)

DC motherboard elevation(Ａ) and (B) type

Turbinebuilding B1
O.P.4.9m

Emergency
generator lost?

×

×

×

×

Lost from flood

A: Lost from flood
B: Power panel
lost from flood

Lost from flood

A: Lost from flood
B: Power panel lostfrom flood○×DC power
supply lost?
Note

Same
O.P.1.9m

Same
O.P.6.5m

×Malfunction from flood

Same
O.P.1.9m

Same (No. 5 &6)
O.P.9.5m

Control bldg
2F(No. 1 & 2)
Control bldg
1F(No. 3 & 4)
O.P.18m(1/no. 2A/B)
O.P.12.2m(No3/4 A/B)○○

Reactor 6: 1 unit OK

2 units from Reactor 3,
2 units from Reactor 4 OK

Lost from flood

・O.P: Onahama Port Construction Reference Plane
・T.P. Tokyo bay standard sea level
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Control bldg 1F(No 1)
Control bldg B1F(No 2)
OuterB1F (No. 3)
O.P.9.5m (no.1A/B)
O.P.7m (no. 2A/B)
O.P.5m (No. 3A/B)○
All units from Reactors 1 & 3,
2 in Reactor 2 OK

Outer B1F
H.P.9.1m(Battery location)○
2 units OK○
Working

107

・O.P: Onagawa Reference Plane
・Accounted in -1m of slide-down by earthquake
・H.P: Hitachi Bay Construction Reference PlaneLessons Learned from Fukushima Dai-ichi…Seawater cooling system…

Extremely Confidential

On-shore motors and pumps for main cooling system malfunctioned due to tsunami – Of
13 emergency generators in Dai-ichi, all but one (air cooling type) malfunctioned. Water-cooling DG
with cooling devices at the coastal side were especially vulnerable.
Loss of functions of emergency generators
Unit 1
Electricalpanel

Emergency
ＤＧ

Fukushima Dai-ichi
Unit 3
Unit 4

Unit 2Usabil Electrical
ity panel

ＤＧ１Ａ

×

ＤＧ1Ｂ

×

Usabil Electrical
ity panel

ＤＧ２Ａ

ＤＧ３Ａ

×

×（※１） ＤＧ３Ｂ

×

×

ＤＧ２Ｂ
（Air cooling）

Usabil Electrical
ity panel

Unit 5Usabil Electrical
ity panel

ＤＧ４Ａ（Air cooling）

Usabil Electrical
ity panel

ＤＧ５Ａ（※２）××（※１） ＤＧ５Ｂ（※２）

×

×

ＤＧ４Ｂ

Unit 6

ＤＧ６Ａ
ＤＧ６Ｂ（Air cooling）

ＨＰＣＳ ＤＧ

Fukushima Dai-ni
Unit 2
Unit 3

Unit 1

UsabilityElectricalpanel

Usabil Electrical
ity panel

×（※2）

ＤＧ１Ａ

×

○

ＤＧ1Ｂ

×（※2）

ＤＧ1H

Usabil Electrical
ity panel

Usabilit Electrical
y
panel

ＤＧ２Ａ

×（※2） ＤＧ３Ａ

×（※2） ＤＧ４Ａ

×（※2）

DG A

○

DG A

○ (non-load DG A

×

ＤＧ２B

×（※2） ＤＧ３Ｂ

○ ＤＧ４Ｂ

×（※2）

DG B

○

DG B (※2)× Sea water
pump stopped

×

ＤＧ2H

×（※2） ＤＧ3H

○ ＤＧ4H○All
malfunctioned
from tsunami

Ｄ/Ｇ

Air cooling type D/G (3 units)
Reactor 2B, Reactor 4B, Reactor 6B
Ｄ/Ｇ

Coolant pumpHeat
exchanger

Atmosphere

Only reactor
6 wasworking

Fukushima Dai-ni
Seawater cooling D/G (12 units)
Reactors 1 - 4A・B・H～～
Seawater pump
Heat
Sea～ ～～～
exchanger～～

Usabilit
Usabilit ElectricalElectrical panelyy panelstandby）

DG B

HPCS D/G (※ ×Sea water
HPCS D/G

2)

pump stopped

Tokai Dai-ni
Usabil Electrical
ity
panel

Usability○×Sea water
pump stopped(DGS)(standby）○(standby）○(standby）

ＤＧ２C (※2)
ＤＧ２D

○

ＤＧ２Ｈ

○

(Legend)○: Working ×: Malfunctioned*1 Power panel malfunction from flood*2 Malfunction from loss of cooling system

Seawater cooling type emergency diesel generator (D/G 10 units)
Reactor 1A・B, Reactor 2A, Reactor 3A・B, Reactor 4A, Reactor 5A&B, Reactor 6A&H
Seawaterpump
Heatexchanger

Unit 4Usabil Electrical
ity panel

Emergency diesel generators at Fukushima Dai-ichi

～～
～～
Sea
～～
～～

Onagawa (Tohoku Electric Power Co)
Unit 1
Unit 2
Unit 3

Coolant pump

Ｄ/Ｇ

Only 3 /12
working● Total of 24 emergency generators malfunctioned. The
loss of cooling function is 1.5 times higher than lossof generator itself (= more orange than pink).
－ Flooded generator (or power panel): 9 cases (pink)－ Cooling system malfunction (motor, pump, etc.): 15 cases (orange)● This is especially so when looking at Fukushima Daiichi Reactors 5 & 6 and Dai-ni, which had relatively
little flooding in the reactor building.
－ Dai-ichi Reactors 5 & 6: 4/4 cooling systems on the coast lost.
－ Fukushima Dai-ni: 6/9 cooling systems on the coast lost.

● Emergency generators for cooling system installednear the coast are vulnerable to tsunami, even withno damage to the generator unit.
－ The only generator that survived in Fukushima Dai-ichi (Reactor 6)
was an air cooling type. It had no cooling device on the coast.
108
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons Learned from Fukushima Dai-ichi…Emergency generator coolant…

Extremely Confidential

Workers were unable to secure coolant for the water-cooling emergency generators.

Dai-ichiReactor1
Availability of
coolant for
emergency
generator

Recovery?

Dai-ichiReactor2

Dai-ichiReactor 3

Dai-ichiReactor 4

Dai-ichi Reactors 5 &6Fukushima Dai-ni

Onagawa×○○

Lost (Seawater coolant)

Only one air coolingtype unit was working(Reactor 6).

Of all 12 units, 3 units
from Reactors 3 & 4
were working.

Remaining 4 units all
failed (seawatercooling type)

Remaining 9 units
failed.
(8 units lost its
seawater coolingsystem andintermediate loop. 1
unit lost intermediate
loop)

○

○

○

Type B seawatercooling system for all
reactors restored
through maintenancecheckup, motor
replacement, andtemporary power
connection.

Flooded pumps andvalves were restored
after being inspected
and repaired in afactory. DG on
standby.

×
Unable to recover

After restoring thedamaged A typeseawater pump forreactor 6, type A
generators started
operating.

Tokai Dai-ni○
All working for
Reactors 1 & 3.

○
2 units working.
One failed.
(Seawater coolant)

2 units lost for
Reactor 2 (1 unit
intermediate loop and
Seawater coolant. 1
unit lost intermediate
loop)○
Flooded pumpinspected andrestored.
DG on standby.

Note: Precondition is that related power panels, power bus-line and other supply routes are working.

109

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Lessons Learned from Fukushima Dai-ichi…Vent operation…

Unable to perform ventilation from the outside – Workers spent too much time preparing
the vent line and failed to execute ventilation.

Right after the tsunami, Reactor 1 lost all functions
for coolant injection and PCV ventilation...

Result of ventilation
Dai-ichiReactor 1

W/W
vent

Dai-ichiReactor 2

Dai-ichiReactor 3

Daiichi
Rctr 4

Daiichi
Rctrs
5&6

Fukushima Daini×△

Succeededin opening
the vent
valve buthydrogen
explosion
occurredright after.

Vent line
constructed
but unable
to hold thenecessarypressure to
open
rupture disc.

Openedthe valve
once, but
could notkeep it
open.

－

－

－
Construc
ted vent
line

Constructedvent line
but could
notmaintain it.

Wat
er
inje
ctio
n

PC
V
vent

－

－

Notes(2F1)

－

○

－

×

Power &seawater lost－×

power&seawater system
lost－power&seawater systemlostfire truck

Water
suppliedthrough
RCIC and
MUWC(emergency DG
worked)×

condensate water feed
(FDW)

×

×
×

Make-Up Water
Condensate (MUWC)

Application

No power (hydraulicpump)High pressure coolant
injection (HPCI)

Shutdown cooling (SHC)－

DamagestatusCore spray (CS)

equi
pme
nt

×
－

Onaga
wa,
Tokai
Dai-ni

equi
pme
nt

△

D/W
vent

Equipment－

No power, motor waterS/C vent valve
Valve no: AO-1601-72

×Power loss/low airpressure

temp power

S/C vent bypass valve
Valve no: AO-1601-90

×No power/low airpressure

improvised
compressor

D/W vent valve
Valve no: AO-1601-1

×

No power/low airpressure

D/W vent bypass valve
Valve no: AO-1601-83

×No power/low air

PCV vent valve
Valve no: MO-1601-210

×

△
Used
temporary gascylinderManualoperation

No power… Then tried to manually open the valve atbasement but gave up as radiation level increased.
(Later succeeded by using the improvised compressor)
Succeeded inmanual release○: Successful－: Not implemented

0.549MPabsで破壊（25%開）

×: Failed

AO
83

AO
1

IA

Abandoned
電磁弁
manual release
due to highradiation level IA
ボンベ● As a result, failed to operate the ventilation at the right time.

排気筒

ラプチャーディスクAO
90

D/W最高使用圧力
0.528MPabs

ベント実施圧力0.954MPabs

閉
RPV

D/W

AO
72

AO
213

閉

閉

ボンベ

● Was not able to operate the ventilation appropriately. On
top of power outage, multiple obstacles such as darkness,transmission problems, parameter loss, frequent aftershocks,
increasing radiation, rubble, etc., made it impossible.
Manual operation of ventilation was also extremely difficult.

MO
210

閉

110

電磁弁

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons Learned from Fukushima Dai-ichi…External power panel…

Extremely Confidential

Dai-ichi Reactors 1 - 4, with power panels to external power flooded, failed cold shutdown.
● Almost all of the crucial panels, such as M/C and P/C, malfunctioned in reactors 1-4 which eventually exploded.
● Especially, all of the power panels were lost at reactors 1 and 3.
Unit 1
Electricalpanel

Emergency
ＤＧ

Emergency

Fukushima Dai-ichi
Unit 3
Unit 4

Unit 2Usabil Electrical
ity panel

ＤＧ１Ａ

×

ＤＧ２Ａ

ＤＧ1Ｂ

×

（Air cooling）

ＤＧ２Ｂ

Usabil Electrical
ity panel

Usabil Electrical
ity panel

ＤＧ３Ａ

××（※１） ＤＧ３Ｂ

×

×

ＤＧ４Ａ
ＤＧ４Ｂ
（Air cooling）

Unit 5Usabil Electrical
ity panel

Unit 6

Usabil Electrical
ity panel

ＤＧ５Ａ（※２）××（※１） ＤＧ５Ｂ（※２）

×

×

×（※2）

ＤＧ１Ａ

×

○

ＤＧ1Ｂ

×

Usabil Electrical
ity panel

Usabil Electrical
ity panel

UsabilityElectrical
panel

ＤＧ２Ａ

×（※2） ＤＧ３Ａ

×（※2） ＤＧ４Ａ

×（※2）

DG A

○

DG A

○ (non-load DG A
standby）(standby）

ＤＧ２B

×（※2） ＤＧ３Ｂ

×（※2）

DG B

○

DG B (※2)× Sea water
pump stopped(standby）

HPCS D/G (※×Sea water

○

DG B

Usability

Electricalpanel

Usability○

ＤＧ２C (※2)×Sea water
pump stopped
(DGS)

○
○

ＤＧ２D

○

ＤＧ２Ｈ

○

ＨＰＣＳ ＤＧ

×（※2）

ＤＧ1H

×

ＤＧ2H

○

ＤＧ4H

○

Ｍ／Ｃ ３Ｃ×

Ｍ／Ｃ 4Ｃ×

Ｍ／Ｃ 5Ｃ×

Ｍ／Ｃ 6Ｃ○

Ｍ／Ｃ １Ｃ×

Ｍ／Ｃ 2Ｃ○Ｍ／Ｃ 3Ｃ○Ｍ／Ｃ 4Ｃ○

Ｍ／Ｃ６－１Ｃ○

Ｍ／Ｃ６－2Ｃ○

Ｍ／Ｃ６－3Ｃ○

Ｍ／Ｃ－2Ｃ×

Ｍ／Ｃ １Ｄ×

Ｍ／Ｃ 2Ｄ×

Ｍ／Ｃ 3Ｄ×

Ｍ／Ｃ 4Ｄ×

Ｍ／Ｃ 5Ｄ×

Ｍ／Ｃ 6Ｄ○

Ｍ／Ｃ １Ｄ○Ｍ／Ｃ 2Ｄ○Ｍ／Ｃ 3Ｄ○

Ｍ／Ｃ 4Ｄ○

Ｍ／Ｃ６－１Ｄ○

Ｍ／Ｃ６－2Ｄ○

Ｍ／Ｃ６－3Ｄ○

Ｍ／Ｃ－2Ｄ○Ｍ／Ｃ ２Ｅ×

Ｍ／Ｃ 4Ｅ×○

Ｍ／Ｃ １Ａ×

Ｍ／Ｃ 2Ａ×

Ｍ／Ｃ ３Ａ×

Ｍ／Ｃ 4Ａ×

Ｍ／Ｃ 5Ａ××

Ｍ／Ｃ 2Ｂ×

Ｍ／Ｃ ３Ｂ×

Ｍ／Ｃ 4Ｂ×

Ｍ／Ｃ 5Ｂ×

Ｍ／Ｃ １Ｓ×

Ｍ／Ｃ ３SA××
Ｍ／Ｃ ２SB×

Ｍ／Ｃ ３SB×

×（※2） ＤＧ3H

ＤＧ４Ｂ

Usabilit
Usabilit ElectricalElectrical panel
y
y
panel

×

Ｍ／Ｃ ２SA2)pump stopped

HPCS D/G(standby）

HPCS DG M/C○Ｍ／Ｃ １H×

Ｍ／Ｃ 2H○

Ｍ／Ｃ 3H○

Ｍ／Ｃ 4H○

Ｍ／Ｃ６－3H○

Ｍ／Ｃ－HPCS×

M/C 1A-1○

M/C 2A-1○

M/C 3A-1○

M/C 4A-1○

Ｍ／Ｃ６－2H
Damaged by
Ｍ／Ｃ６－2Ａ
Ｍ／Ｃ６－１Ａ ×earthquake○

M/C 6A-1○

Ｍ／Ｃ６－3Ａ○

Ｍ／Ｃ－2Ａ-1

×

M/C 6A-2

×

M/C 1A-2○

M/C 2A-2○

M/C 3A-2○

M/C 4A-2○

Ｍ／Ｃ６－１Ｂ

Ｍ／Ｃ６－2Ｂ○

Ｍ／Ｃ６－3Ｂ○

Ｍ／Ｃ－2Ａ-2

××

M/C 6B-1

×

M/C 1B-1○

M/C 2B-1○

M/C 3B-1○

M/C 4B-1○

Ｍ／Ｃ６－１Ｓ×

Ｍ／Ｃ６－２SA-1○

Ｍ／Ｃ６－3SA-1○

M/C 6B-2

×

M/C 1B-2○

M/C 2B-2○

M/C 3B-2○

M/C 4B-2○

Ｍ／Ｃ６－1Ｅ

×

Ｍ／Ｃ６－２SB-1○

Ｍ／Ｃ６－3SB-1○

Ｍ／Ｃ－2Ｂ-1

×

Ｍ／Ｃ－2Ｂ-2

×

Ｍ／Ｃ－2E×

M/C 5SA-1

×

M/C 1SA-1○

M/C 3SA-1○

Ｍ／Ｃ６－2SA-2○

Ｍ／Ｃ６－3SA-2○

M/C 5SA-2

×

M/C 1SA-2○

M/C 3SA-2○

Ｍ／Ｃ６－2SB-2○

Ｍ／Ｃ６－3SB-2○

M/C 5SB-1

×

M/C 1SB-1○

M/C 3SB-1○

M/C 5SB-2

×

M/C 1SB-2○

M/C 3SB-2○

P/C 1C×

P/C ２C○P/C ３C×

P/C 4C-P/C 5C×

P/C 6C○P/C 1C-1

×

P/C 2C-1○

P/C 3C-1○

P/C 4C-1○

P/C 4-1C○P/C 4-2C○P/C 4-3C-1○

P/C 2C×

P/C 1D×

P/C ２D○P/C ３D×

P/C 4D○P/C 5D×

P/C 6D○P/C 1C-2

×

P/C 2C-2

×

P/C 3C-2

×

P/C 4C-2

×

P/C 4-1D○P/C 4-2D○

P/C4- 3C-2○

P/C 2D○P/C 4Ｅ×

P/C 6E○P/C 1D-1○

P/C 2D-1○

P/C 3D-1○

P/C 4D-1○

P/C 4-3D-1○

P/C 2A×

P/C ３Ａ×

P/C 4Ａ-P/C 5Ａ×

P/C 6Ａ-1

×

P/C 1D-2

×

P/C 2D-2

×

P/C 3D-2○

P/C 4D-2

×

P/C 4-1A×

P/C 4-2A○

P/C 4-3D-2○

P/C 2B×

P/C 5Ａ-1○

P/C 6Ａ-2

×

P/C 1A-1○

P/C 2A-1○

P/C 3A-1○

P/C 4A-1○

P/C 4-1B×

P/C 4-2B○

P/C 4-3A-1○

P/C 2S×

P/C 5B×

P/C 6B-1

×

P/C 1A-2○

P/C 2A-2○

P/C 3A-2○

P/C 4A-2○

P/C 4-1S×

P/C 4-2SA○P/C 4-3A-2○

P/C 5B-1○

P/C 6B-2

×

P/C 1B-1○

P/C 2B-1○

P/C 3B-1○

P/C 4B-1○

P/C 4-2SB○P/C 4-3B-1○

P/C 2B-2○

P/C 4B-2○

P/C 4-3B-2○

P/C 1AP/C 1BP/C 1S××

P/C ２Ｅ×

P/C ２Ａ○P/C ２Ａ-１

×

P/C ２Ｂ○

ＤＣ１２５Ｖ
main&transfer
bus 1Ａ
ＤＣ１２５Ｖ
main&transfer
１２５ＶＤＣ bus 1Ｂ

××

P/C ３ＢP/C ３ＳＡ×
P/C ２ＳＢDC
power

Usabil Electrical
ity panel

Ｍ／Ｃ 2Ｃ

Ｍ／Ｃ １Ｂ

Normal（Air cooling）

Electrical
panel

Tokai Dai-ni

×NormalＰ／Ｃ

ＤＧ６Ｂ

UsabilityOnagawa (Tohoku Electric Power Co)
Unit 1
Unit 2
Unit 3

Unit 4

Ｍ／Ｃ １Ｃ

Ｍ／Ｃ

Emergency

ＤＧ６Ａ

Fukushima Dai-ni
Unit 2
Unit 3

Unit 1ＤＣ１２５Ｖ
main&transfer
bus 2Ａ
ＤＣ１２５Ｖ
main&transfer
bus 2Ｂ×××

P/C ３ＳＢ

ＤＣ１２５Ｖ
main&transfer
bus 3Ａ
ＤＣ１２５Ｖ
main&transfer
bus 3Ｂ×

P/C 4Ｂ

○

×

×

○

○

ＤＣ１２５Ｖ
main&transfer
bus ４Ａ
ＤＣ１２５Ｖ
main&transfer
bus ４Ｂ××

P/C 5SＡ×

P/C 1B-2○

P/C 3B-2○

P/C 5SＡ-1

×

P/C 1SA○P/C 3SA○P/C 4-3SA-1○

P/C 5SB×

P/C 1SB○

P/C 3SB○

P/C 4-3SB-1○

P/C 4-3SA-2○

P/C 4-3SB-2
１２５ＶDC
main&transfer
bus 3Ａ
１２５ＶDC
main&transfer
bus 3Ｂ○

ＤＣ１２５Ｖ
main&transfer
bus 5Ａ
ＤＣ１２５Ｖ
main line
board 5Ｂ○○

ＤＣ１２５ＶDIST CENTER 6Ａ

ＤＣ１２５ＶDIST CENTER 6B○○

ＤＣ１２５Ｖ
main line
boardＡ
ＤＣ１２５Ｖ
main line
board Ｂ○○

ＤＣ１２５Ｖ
main&transfer
bus Ａ
ＤＣ１２５Ｖ
main&transfer
bus Ｂ

○

○

ＤＣ１２５Ｖ
main&transfer
bus Ａ
ＤＣ１２５Ｖ
main&transfer
bus Ｂ

○

○

ＤＣ１２５Ｖ
main&transfer
bus Ａ
ＤＣ１２５Ｖ
main&transfer
bus Ｂ

○

○

１２５ＶDC
main&transfer
bus 1Ａ
１２５ＶDC
main&transfer
bus 1Ｂ○○

１２５ＶDC
main&transfer
bus 2Ａ
１２５ＶDC
main&transfer
bus 2Ｂ○○○○

ＤＣ１２５Ｖ
main&transfer
bus 2Ａ
ＤＣ１２５Ｖ
main&transfer
bus 2Ｂ

○

○

A/B

Ａ

CCS A

×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ×

ＲＨＲＳ Ａ○ＲＳＷ Ａ

RHRS A

×

CCS B

×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ○ＲＨＲＳ Ｂ×

ＲＨＲＳ Ｂ

○

ＲＳＷ Ｂ

○
ＲＳＷ Ａ
× ＲＣＷ/ＲＳＷ ＲＳＷ Ｂ○

Sea waterＢsystem○RHRS B○

HPCS DGSW

×

HPCSS

×

HPCSS

×

HPCSS

○

HPCSS

○

ＨＰＳＷ

× ＨＰＣＷ ＨＰＳＷ
submerged○

HPCS DGS

External power×
All 6 lines were lost due to the earthquake：Lost functions：Unable to activate due to electrical board and/or cooling system were lost
：Incoming power was inaccessible due to the loss of electrical supply source○
3/4 lines were lost due to earthquake（Tomioka line 1L only 500kV continued to receive power）

Information on DC power of system-H was omitted.

submerged○
4/5 lines were lost due to earthquake（Matsushima Main line 1L Only 275 kV survived）○

×
Both lines were lost due
to earthquake

111

Loss of functions below were based on the estimation by the project;
・ Onagawa's M/C, P/C, and Tokai Dai-ni's P/C electrical panels

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons Learned from Fukushima Dai-ichi…Connecting power supply vehicles…

Extremely Confidential

With almost no working panels for the power supply vehicles to connect, it was very
difficult to supply power.
Power supply vehicle arrangements● Power supply vehicle arrived right after the tsunami (High voltage vehicle)－ March 11 approx. 22:00 First group arrives with one unit.
－ March 12 approx. 01:20 4 units arrive (total 5 units)－ March 12 approx. 03:00 7 units arrive (total 12 units)● Same as above (Low voltage vehicle)－ March 11 approx. 23:30 2 units from Self Defense Force－ March 12 approx. 07:00 3 more units arrive

Difficulty with connection● Few power supply vehicles were rounded up by dawn of March 12.
● However, there was trouble connecting them as very few power panels (M/C, P/C) were working
due to tsunami as well as time was consumed in identifying working ones.
● Furthermore, factors such as rubble, aftershocks, transmission problems, insufficient heavyequipment, hindered the set-up of lines to connect vehicles.
● All the preparations made for restoring power in Fukushima Dai-ichi Reactor 2 had to start fromscratch when Reactor 1 exploded.
112
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons learned from Fukushima Dai-ichi…Design Philosophy…Hydrogen explosion…

Extremely Confidential

In reactor 1 with no coolant functionality, core meltdown caused the cladding tube
around the fuel rods to oxidize and built up a massive amount of hydrogen.
Mechanism of hydrogen generation● Without power and cooling, the core’s temperature and pressure surged. This
lowered the water level in the core and eventually caused the fuel rods to be
exposed above the coolant water.
Zirconium alloy

Hydrogengenerated● As the temperature in the core increased, the cladding tube around the fuel rods
(zirconium alloy) started melting and oxidizing at approximately 900℃, whichraised core temperature further.

Melted fuelH2

● The chemical reaction between the molten cladding tubes (zirconium) andoxygen in the steam in the pressure vessel produced a massive amount ofhydrogen (zirconium-water reaction).
● According to TEPCO’s simulation, in Reactors 1, 2 and 3, with the water level
down and the fuel rods exposed, core damage (melting of fuel) possibly
started in about 2 hours after the exposure of the fuel rods.

図出典： 徹底解剖 東日本大震災 (双葉社)

Simulated time to core damage(From the timing of Fukushima Dai-ichi Reactor 1
Reactor 2
earthquake) (If water level is below the fuel) (If data of water level is correct)

Reactor 3
Reactor 2(If water level is below the fuel) (If data of water level is correct)

Reactor 3(If water level is below the fuel)Approx. 3 hrs
Approx. 3 hrs
・March 11 17:46
・March 11 17:46

Approx. 75 hrs
Approx. 75 hrs
・March 14 17:46
・March 14 17:46

Approx. 75 hrs
Approx. 75 hrs
・ March 14 17:46
・ March 14 17:46

Approx. 40 hrs
Approx. 40 hrs
・ March 13 06:46
・ March 13 06:46

Approx. 40 hrs
Approx. 40 hrs
・March 13 06:46
・March 13 06:46

Core damage
started:Approx. 4 hrs
Approx. 4 hrs
・March 11 18:46
・March 11 18:46

Approx. 77 hrs
Approx. 77 hrs
・ March 14 19:46
・ March 14 19:46

Approx. 77 hrs
Approx. 77 hrs
・March 14 19:46
・March 14 19:46

Approx. 42 hrs
Approx. 42 hrs
・March 13 08:46
・March 13 08:46

Approx. 42 hrs
Approx. 42 hrs
・ March 13 08:46
・ March 13 08:46

Damage to containment
vessel occurred:

Approx. 15 hrs
Approx. 15 hrs
・March 12 05:46
・March 12 05:46

No damage
No damage

Approx. 109 hrs
Approx. 109 hrs
・March 16 03:46
・March 16 03:46

No damage
No damage

Approx. 66 hrs
Approx. 66 hrs
・ March 14 08:46
・ March 14 08:46

Core exposure started:

Note) Source May 23, 2011 Tokyo Electric Power Company Corp. "“Analysis and effect evaluation of the records on operations and accidents at Fukushima Dai-ichi Nuclear Power Plant in
Tohoku Region Pacific Coast Earthquake”
・Date of analysis: May 16, 2011
・
Method： Used the gathered information on condition of the equipment and plant operation when the earthquake first occurred as input for simulation information, and analyzed.
・Software： Accident Analysis Code (MAAP＝Modular Accident Analysis Program)
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved113Lessons Learned from Fukushima Dai-ichi…Design philosophy…Hydrogen explosion…

Extremely Confidential

The reactor building had no system to “detect” or “release(*)” hydrogen, resulting in a
massive explosion. ※)Emergency gas treatment system did not function because of the power outage
Reactor No.1 (East side)

Reactor No. 3 (East side)

Reactor No. 4 (East side)

Hydrogen built up
in the 5th floor

Hydrogen built up in the 5th &partially in the 4th floor (north-east)

Hydrogen built up in the
5th & partially in the 4th, floor (east west)● Leak path-2 (Reactors 1&3): It is also possible that high- ● Leak path (Reactor 4) : It is estimated hydrogen produced at
Reactor 3 back-flowed into reactor 4 through connecting pipes
pressure & -temperature gas passed through vent lines andused for the emergency gas processing system.
damaged the pipes and valves during the ventilation of the
4号炉原子炉建屋
PCV, creating gaps for the hydrogen to leak through.

● Leak path-1 (Reactors 1&3): It is estimated thehydrogen leaked into the reactor building throughgaps in the connections and piping (hatch, drywellflange, electric penetration).
原子炉建屋

原子炉建屋

５階

主排気筒

排気ダクト→

５Ｆ

5階南側排気ダクト
4階西側排気ダクト

OP.39920
燃料貯蔵プール リアクターキャビティ 機器仮置プール
↓
↓
↓

４Ｆ

5F

ドライウェルフランジ

４階

4F

207

３階

３Ｆ
HVE3-1A

OP.26900

AO

AO

208

GD

↑3号機 emergency gas process-----↓4号機

AO

BF3

BF3

3F

-4

-2

電気ペネトレーション：モジュール型：キャニスタ型

Hydrogenback flow from
Reactor 3

4階東側排気ダクト

OP.32300
AO

排
気
塔

GD

２階

２Ｆ
AO

OP.18700

バグフィルターAO

BF3

HVE3-1B

BF3
-5A

SGTS

-5B

A
O

OP.16780
OP.16400
OP.15300

ハッチ

AO
AO
漏洩ガス流
BF3

１階

AO

SGTS

AOC

GD

BF3
-7

186

2F

SGTS
SGTS

AO

排風機 AO

AO

AO

GL
A
O

AO

１Ｆ

OP.14688

AO

back flow gas
排風機-6emergency gas process

OP.10200

ＳＧＴＳ

AO

× BF3 -14

電気ペネト
レーション

原子炉格納容器< Leak path from containment vessel (estimated) >

1F

AO
BF3

AO

×

-17

BF3

AOC
187

AO
GD

BF3
-9

-8

AO

AO

205

206

損傷の可能性が考えられる箇所
の例

ＳＧＴＳ

ＭO
２7１

114
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen Explosion... Overview...

Extremely Confidential

In reactor 1 & 3, oxidation of zirconium of the fuel rods, caused by core damage, generatedhydrogen, which leaked into reactor buildings from PCV, and eventually exploded. Hydrogenfrom reactor 3 flowed into reactor 4 through a shared vent line, accumulated and exploded.
Fukushima Dai-ichi Unit 1

Unit 2

Unit 3

Unit 4

Why was thehydrogengenerated?

● Reactions between the molten zirconium fuel rods and water (water-zircaloy
reaction) caused massive hydrogen buildup within the containment vessel.

● No hydrogen buildup in
Unit 4.

When did it
occur?

● 4 hours after the earthquake(3/11 approx. 18:46 ※1)● 77 hours after the earthquake(3/14 approx. 19:46 ※1)● 42 hours after the earthquake(3/13 approx. 8:46 ※1)● 42 hours after the earthquake(3/13 approx. 8:46 ※1)

Where did it
leak from?

● Multiple possible sources● Multiple possible sources● Multiple possible sources● Hydrogen from Unit 3 leaked
into the reactor building No.4
through the SGTS pipe.

・Pressure Vessel ⇒ Primary Containment Vessel (PCV):The hydrogen gas transferred to the S/C when the core was decompressed via SRV,
and leaked to the D/W from the sheath of the SRV.

・ PCV ⇒ Reactor Building:
Leaked through the D/W flangearea, power penetration, hatch,
air-conditioner exhaust, etc, tothe upper level of the nuclear
reactor building.

Where did it
accumulate?
What
triggered it?

・ Pressure in D/W exceeded its

・ Same as Unit 1

capacity of 0.75MPa. This caused
damage to areas that weren’t able
to cope with the pressure (i.e.
bottom of the S/C vent line).

● 5th floor(※2)● Presumably in the basement area ● 5th & 4th floors, and possibly(No photographic record)
3rd floor (※2)● Since hydrogen is lighter thanair, it travelled and spread tothe operation floor above. It
exploded when it reached the
combustible density 4% - 75%(unable to determine theignition source since energy
required for ignition is only
0.02mJ).

● Damage could have been caused
either by the hydrogen explosion orpressure built-up in the PCV.
For the former, presumed to be the
S/C’s narrow occluded section
since the damaged area is not aswide as for Reactors 1 and 3. It isinferred that it is most likely notcaused by hydrogen explosion.

● Same as Unit 1● 4th and 5th floors (※2)
● Same as Unit 1

115※1: Start of fuel damage based on analysis. ※2: Judging from the photos.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen explosion...Pressure vessel damage simulation

Extremely Confidential

Based on simulations by TEPCO, the pressure vessels in reactor No. 1-3 were alldamaged and their PCV could have been damaged with massive H2 leaked, if their waterlevels were below the fuel rods (i.e. Records of water level are not accurate).
Fukushima Dai-ichi Unit 1(Water level below fuel)Unit 2(Water level above fuel)Unit 2(Water level below fuel)Core exposure start

approx. 3 hrs
approx. 3 hrs
・3/11 17:46
・3/11 17:46

approx. 75 hrs
approx. 75 hrs
・3/14 17:46
・3/14 17:46

Core damage start

approx. 4 hrs
approx. 4 hrs
・3/11 18:46
・3/11 18:46

Damage toreactor pressure vessel

Analysis result

Unit 3(Water level above fuel)Unit 3(Water level below fuel)approx. 75 hrs
approx. 75 hrs
・3/14 17:46
・3/14 17:46

approx. 40 hrs
approx. 40 hrs
・3/13 06:46
・3/13 06:46

approx. 40 hrs
approx. 40 hrs
・3/13 06:46
・3/13 06:46

approx. 77 hrs
approx. 77 hrs
・3/14 19:46
・3/14 19:46

approx. 77 hrs
approx. 77 hrs
・3/14 19:46
・3/14 19:46

approx. 42 hrs
approx. 42 hrs
・3/13 08:46
・3/13 08:46

approx. 42 hrs
approx. 42 hrs
・3/13 08:46
・3/13 08:46

approx. 15 hrs
approx. 15 hrs
・3/12 05:46
・3/12 05:46

No damage
No damageapprox. 109 hrs
approx. 109 hrs
・3/16 03:46
・3/16 03:46

No damage
No damageapprox. 66 hrs
approx. 66 hrs
・3/14 08:46
・3/14 08:46

approx. 18hrs
approx. 18hrs
・3/12 08:46
・3/12 08:46
・D/W Approx. 3cm diam.
・D/W Approx. 3cm diam.

approx. 21 hrs
approx. 21 hrs
・3/12 11:46
・3/12 11:46
・D/W Approx. 10cm diam.
・D/W Approx. 10cm diam.

Same as left
Same as left

No record
No record

Same as left
Same as left

approx. 50 hrs
approx. 50 hrs
・3/13 16:46
・3/13 16:46
・D/W Approx. 7cm diam.
・D/W Approx. 7cm diam.

approx. 87 hrs 28 min
approx. 87 hrs 28 min
・3/15 06:14
・3/15 06:14
noise around S/Cnoise around S/C・S/C approx. 10cm diam.
・S/C approx. 10cm diam.
・3/14 23:00
・3/14 23:00
assumed SR valve 1 closed
assumed SR valve 1 closed
・ Scenario based on
・ Scenario based on
analysis of records.
analysis of records.

Same as left
Same as left

No record
No record

Same as left
Same as left

・Scenario based on
・Scenario based on
analysis of records.
analysis of records.

Same as left
Same as left

(Time elapsed since earthquake)

Analysis Precondition(Time elapsed since earthquake)

Leak from containment
Vessel’s gas phase section
Same as above(to greater extent)

・Theory: IC not working
・Theory: IC not working
after DC power outage.
after DC power outage.
・Phenomenon theorized・Phenomenon theorizedbased on analysis of records.
based on analysis of records.

Note) Source: May 23, 2011, Tokyo
Electric Power Company
Corp. “Analysis of Tohoku
region Pacific coast earthquake Fukushima Dai-ichi Nuclear Power Plant Operation
Record and Accident Record and Effect Evaluation” (May 23 2011)
・
Date of analysis: 5/16/2011
・
Method: Used the gathered information on condition of the equipment and plant
operation when the earthquake first occurred as input for simulation information, andanalyzed.
・Software: MAAP＝Modular Accident Analysis Program

Same as left
Same as left

● Core Damage of Reactors 1 - 3 started approx. 2 hrs after core exposure.
● Pressure vessel in reactor No.1 was already damaged before water116
injection (March 12th, 5:46, 2011)
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen explosion... Unit 1

Extremely Confidential

Unit 1: Only the 5th floor was badly damaged – It seems that hydrogen had
accumulated primarily on the 5th floor.
Unit 1 - after explosion

East Face

West Face

South Face

North Face

117
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen explosion...State of Unit 3

Extremely Confidential

Unit 3: 5th floor and north wall of the 4th floor were badly damaged – It seems thathydrogen had accumulated primarily on the 5th and possibly on the 4th floor.
Dai-ichi Unit 3 - after explosion

East Face

West Face

South Face

North Face

118
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen explosion...State of Unit 4

Extremely Confidential

Unit 4: 5th floor, and east & west walls of 4th floor were badly damaged – It seems
that hydrogen had accumulated mainly on the 5th and 4th floors.
Dai-ichi Unit 4 - after explosion

East Face

West Face

South Face

North Face

119
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen explosion...Hydrogen leak theory...Unit 1&3

Extremely Confidential

H2 leak scenario at unit 1&3: (1) Through PCV penetration: As the seals in electric cablingroutes and hatches of PCV are made of epoxy and rubber, the high temperature andpressure caused the seals to degrade and they consequently allowed H2 to leak through.
原子炉建屋
Reactor Building
5th Fl.
５階

OP.39920

ドライウェルフランジ
Drywell
Flange4th Fl.
４階

Reactor Pressure Vessel

3rd
３階Fl.

電気ペネトレーション
Electric Penetration
Module Type
：モジュール型：キャニスタ型
Canister Type

ハッチ
Hatch

OP.32300

OP.26900

Moved to the upper floors throughstairway and hatch
２階
2nd
Fl.
OP.18700

OP.16780
OP.16400
OP.15300
OP.14688

1st Fl.
１階

OP.10200

Electric
電気ペネト
レーション
routing

Note: The (presumed) leakage paths
may vary between reactor 1 and 3 due
to differences in the system structures.

120
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen explosion...Hydrogen leak theory...Unit 1&3

Extremely Confidential

H2 leak scenario at unit 1&3: (2) Through the vent exhaust system: There is a possibility
that high-temperature/-pressure gas flowed through the exhaust duct when the S/C wasvented. The gas damaged the duct and valves, and created spaces for hydrogen to leak.
Reactor
Building
原子炉建屋

Main Exhaust Outlet
主排気筒

排気ダクト→

５Ｆ

Ventilation Duct

Note: The (presumed) leakage
paths may vary between Unit 1
and Unit 3 due to differences inthe system structures.

リアクターキャビティ
機器仮置プール
Spent燃料貯蔵プール
Fuel Pool Reactor
Cavity DSP
↓

↓

↓

４Ｆ

AO
207

３Ｆ
HVE3-1A
AO

AO

208

GD

AO

BF3

BF3
-4

-2

GD

２Ｆ
AO

Bag
Filter
バグフィルターAO

BF3

HVE3-1B

BF3
-5A

-5B

Gas leak
１Ｆ

Vent gas flow

AO
AO

AOC

BF3

186

GD

BF3
-7

-6

ＳＧＴＳ

AO

×
BF3

×
Primary原子炉格納容器
Containment Vessel

AO

AO

205

206

-14

Examples of areas that
may have been damaged.

AO
BF3

AO

-17

BF3

AOC
187

AO
GD

BF3
-9

-8

ＳＧＴＳ

ＭO
２7１

121

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedHydrogen explosion...Hydrogen leak theory...Unit 4

Extremely Confidential

H2 leak scenario at unit 4: Reverse flow from unit 3: The emergency SGTS* exhaust ductof Unit 4 is connected to Unit 3 right before the flue. Gases (including hydrogen) from
Unit 3 may have flowed through into Unit 4. (*: Stand-by Gas Treatment System)
Reactor
Building No. 44号炉原子炉建屋

Exhaust duct onsouth side of 5th Flr

5階南側排気ダクトthExhaust duct on north side of 4 Flr
4階西側排気ダクト

排
気
塔

5F
4階東側排気ダクト
Exhaust duct on

4F

Vent gas flow

east side of 4th Flr↑3号機-----↓4号機

3F

SGTS
A
O

A
O

AO

SGTS
SGTS

排風機

AO

GL
A
O

AO

2F

AO

SGTS

Reverse
gas
flow
逆流ガス

AO

AO
排風機

1F

122
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedhydrogen explosion mechanism...pressure vessel damage

Extremely Confidential(Reference) Unit 3 & 4 SGTS exhaust duct

↑Unit 4 SGTS exhaust duct
interconnect

Flue →↓Unit 3

123

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Lessons
LessonsLearned
LearnedandandCountermeasures
Countermeasures
・・WhatWhatlessons
lessonscan
canbebelearned
learnedfrom
fromthethefacts?
facts?
・・WhatWhatmeasures
measurestotobe
betakentakenininorder
ordertotoprevent
preventrecurrence?
recurrence?

124
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Lessons
LessonsLearned
LearnedandandCountermeasures
Countermeasures--LessonsLessonsLearned
Learned--125
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Earthquake and Tsunami...

Extremely Confidential

Earthquake and Tsunami
Cause・ Earthquake
・ External power outage
・ Communication
function problem
・ Liquefaction of road &infrastructure, andscattered debris fromthe quake and tsunami.
・ Time and day of thedisaster

Event / Issue

Measures / Lessons

・Auto stop (scram) of core reactor activated according to design. Recovery operations
performed on DG auto-activation due to external power failure. Operator responded asplanned .

・ Nuclear reactor earthquake
response was according todesign.

•After the auto scram was triggered by earthquake, some DGs were activated by mistake inplants that didn’t experience external power outage (because of the loss of generator’s fieldmagnet?). DG is an important emergency power source, so we need to consider whether theactivation was appropriate.

・ Investigate the cause ofactivation.
・ Add DG auto-activationinterlock on earthquake scram.

•No major damage to the facilities from the earthquake. Detailed examination on the earthquake
disaster will require some time, so whether lessons learned from Kashiwazaki were effectively
applied has yet to be verified.

・ Check lessons learned from
Kashiwazaki-Kariwa Nuclear
Power Plant at Chuetsu
offshore earthquake.

•

The earthquake caused problems with communications. There were major issues in sharing
information, giving instructions or commands, and making decisions. Whether the emergency
satellite phone, and fire department and local government hotline were functioning and utilized
have yet to be verified.

・ Secure and reinforce means ofcommunication in case ofdisasters such as earthquakes.

•

Recovery process delayed due to difficult access along roads and facilities caused by roadliquefaction from earthquake and debris from the tsunami.

・ Reinforce main road to preventliquefaction, and secure
multiple access routes.

•

The seismic motions recorded in Fukushima and Onagawa were as predicted. Aside from theseismic motion in some areas of Onagawa where the actual quake was stronger, the readings
were on par with the prediction. This indicates that the design for seismic motion is reliable.

・ Design against earthquake wasappropriate.

・The earthquake happened during the day on a weekday, but we need to verify whether workers
would have been able assemble at the power plant according to the manual if it occurred atnight and on a holiday.

・ Consider response proceduresfor disasters occurring on aholiday and at night.

126
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Earthquake and Tsunami...

Extremely Confidential

Earthquake and Tsunami - 2
Cause・ Anti-tsunami design
underestimated・ Seawater pump flooded
from tsunami

Event / Issue
・・

Measures / Lessons

Tsunami impact larger than the prediction made by the Japan Society of Civil Engineers
・ Is the prediction from JSCE really(JSCE) 2002 (Fukushima Dai-ichi = 5.7m, Dai-ni = 5.2m). The tsunami (Dai-ichi = max
adequate?
15.5m, Dai-ni = max 7.0m) greatly affected the safety of the plant. Furthermore, it’s not clear ・ Consider to estimate tsunami
whether the accuracy of the tsunami estimate data had been seriously reviewed in the past 7
risk voluntarily and periodically.
years.

・ Tsunami countermeasures for
The height of the tsunami that impacted the Onagawa Power Plant and Tokai Dai-ni Power
seawater pumps. (Reinforce
Plant was on par with that estimated by the Japan Society of Civil Engineers (2002 estimate).
pressure resistance and water
However, some areas of the plant were not sealed properly, so seawater entered the facility.
seal.)The emergency seawater pump malfunctioned due to flooding, causing the emergency DG tomalfunction.

・Tsunami impact destroyed the power plant’s structures and equipment, scattering debris
・ Revise risk assessment toacross its path. The debris became an obstacle during the recovery process. When
include consideration of thedeliberating measures against tsunami the discussion shouldn’t be limited to the height of thepower of the tsunami.
tsunami, but should also include its power.

・In Fukushima Dai-ichi and the Onagawa power plant, the tsunami swept the heavy oil tanks
onto the road, blocking access to the plants. This affected the speed of the recovery process
and heavy oil was also released to the sea.

・ Bolt down the gasoline tanks.

・ Debris created from thetsunami.

・The debris scattered by the tsunami greatly affected the mobility of supply transport. Thereneeds to be a countermeasure to enable swift actions in securing the safety of the plant.

・ Secure heavy machinery andoperators for clearing debris.

・ Seawater coolant pumpvulnerable against
tsunami・

Although the facilities in Fukushima Dai-ichi and Dai-ni were built in an area higher than the ・ Store mobile power supplies andestimated tsunami height, the seawater pumps were not . The pumps were damaged by theseawater pumps.
tsunami and malfunctioned.

・ Tsunami risk assessment
system based on "height"
・ Gasoline tank swept
away by tsunami

127
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Earthquake and Tsunami...

Extremely Confidential

Earthquake and Tsunami - 3
Cause
・ Major flooding(seawater) of turbine
building from thetsunami・ The tsunami hit whenturbine building's supply
transport entrance wasopen.
・ Seismic-isolation tower’s
emergency power lostfrom the tsunami.
・ Seawater pumps
malfunctioned due todamage from tsunami.
・ Insufficient AM andtraining for simultaneous
SBO occurrences of allplants.

Event / Issue

Measures / Lessons•

Buildings connected to the turbine and nuclear reactor buildings were flooded badly, andequipment in the basement and ground floor were damaged and stopped functioning. The
plant’s cooling system was greatly affected due to flood damage of the emergency DG,
DC and AC power panels, etc.

・ Reconsider the location of Diesel
generators, DC power panels, andAC power panels. Stock mobile
power supply vehicles.

•

During regular inspections, the turbine building’s large entrance is used for delivery of
supplies. The entrance was left open during and after the earthquake, allowing seawaterfrom the tsunami to enter to the building. The flood resulted in the loss of the DC power
supplies.

・ Revise operations of wide
entrances since they arevulnerable to flooding. Conduct
training.

•

There was no power in the Fukushima Dai-ni emergency response room following thetsunami impact. Limitations in the emergency response room’s infrastructure may havean affect on the speed of the plant’s recovery process.

・ Reinforce the Seismic-isolation
tower against tsunami. Secure
emergency power supply.

•

In Fukushima Dai-ichi, almost all seawater pumps malfunctioned from the tsunami. There
wasn’t much damage to the pumps themselves, but most suffered damage to the motor
insulation.

・The tsunami impact instantly compromised the entire power plant. The AM was notdesigned for response to an instant devastating blow to the entire plant. Furthermore,measures against disasters with low probability of occurrence may not have been seriously
taken into account because of the application of the PSA method. To learn from this, it’s
important to not just make hard and soft preparations in responding to instant damage tothe entire plant, but to enhance plant-wide training as well.

・ Keep washing equipment for motor
coil within the site and stock spareparts.
・ Reinforce hard and soft
preparations for plant-wide SBO.
Reinforce Training.

128
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Power outage...

Extremely Confidential

Power outage (Fukushima Dai-ichi) - 1
Cause

Event / Issue

Measures / Lessons

・ DC power supply flooded
from the tsunami•

AC and DC power supplies in the turbine building’s first floor and basement were lost fromthe tsunami. It is important to improve the facility's air seal, water seal, and pressure
resistance to protect the power supplies.

・ Improve air protection, water
protection, and pressure
resistance of power facilities

Flood entered throughthe air inlet•

Emergency DG malfunctioned due to seawater entering the air inlet.

・ Apply water proof solution for air
inlet

・ Instant loss of DC power
supply from flooding•

DC power is the most important source in the plant. It powers the high pressure coolingdevices and the main control room’s measuring equipment and lights.
In Fukushima Dai-ichi, the DC battery room was located in the basement of the turbine
building, so it was lost instantly in the flood. With no power, the high pressure coolingsystem didn’t function. When the pressure in the reactor was reduced, attempts to cool the
nuclear core with the alternative low pressure cooling system had been made but failed andresulted in core meltdown, and eventually to the hydrogen explosion (Fukushima Dai-ichi
Unit 1).

・ Secure alternative DC power
supply. It's important to havediversity

・ Complete external power
outage•Fukushima Dai-ichi Reactors 1 – 6 lost external power from the earthquake. Plants that
didn’t experience external power loss and those that were able to recover at least one
emergency power supply achieved cold shutdown. Securing external power supply directly
leads to prevention of fuel damage.

・ Improve earthquake resistance of
external power supply
・ Increase the number of external
power supply routes (multiplex)
・ Link external power on each plant(multiplex)

・ Emergency power
supplies located ataltitude lower thantsunami crest・ Power supplies relied onseawater cooling system.

•

In Fukushima Dai-ichi, only one emergency DG of reactor 6 was functioning.
It is located in the northern part of the plant which is at a higher altitude (O.P.13m) thanReactors 1 - 4. The height of the flood wave only reached up to 1m there.
In addition, the Reactor 6 emergency DG uses air instead of seawater for its cooling system,
so it wasn't affected by the flood.

・ Consider placing emergency DGs
in higher places.
・ Secure emergency power supplies
for the various cooling systems
with different power types.

・

129
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Power outage...

Extremely Confidential

Power outage (Fukushima Dai-ichi) - 2
Cause・ Not anticipated in AM (slowrecovery of AC power at SBO)
・ Concurrent AC and DC power
outage・ Instant loss of all DC powerfrom flooding. Unable tocharge ‘submerged’ batteries
from DC power supply.

Event / Issue•

Only short period station blackout was anticipated in the AM countermeasures. However,in Fukushima Dai-ichi, the power outage lasted up to a few days.
This sort of situation was not covered in the recovery procedure manual.

・ Revise the procedures to
respond to long term loss of all
AC power•

The countermeasures in the AM all assume definite recovery from station blackout sothere isn’t any countermeasure against loss of all AC and DC power at once. The plant
was designed to be able to supply 8 hours of DC power in case of power outage, but it
did not work. In Fukushima Dai-ichi Unit 3, where DC power was retained, the DC
power lasted more than a day (1.5 – 3 days) by cutting off unnecessary power
consumption, but they failed to set up the low pressure cooling system for backup during
this period. When the batteries were depleted the plant lost its high pressure coolingsystem, and instrumentation in the main control room stop functioning.

・ Secure alternative AC power
supply・ Secure alternative DC power
supply・ Create manual for swift
installation

The DG in Fukushima Dai-ichi Unit 6 still worked and they were able to connect power
to Unit 5. This together with the use of the power supply vehicle allowed cold shutdown
in Dai-ichi Reactors 5 & 6. There was no power line connecting from Units 5 & 6 toUnits 1 - 4.

・ Improve power supply line
within the site (per voltage
class)•

After the tsunami, some plants were able to partially restore power with the power supply
vehicle. Utilization of power supply vehicles was effective.

・ Increase number and varietyof power supply vehicles,
revise designations, define
connection areas andprocedures, and reinforce
training.

•

The greatest fear and cause of despair for operators is the loss of the parametermonitoring function. In a severe accident such as this one, operators need to be calm andutilize their knowledge and skills acquired through training to stabilize the plant andbring it to cold shutdown. In order to achieve this, it is crucial to maintain
instrumentation and control switches (and power for it).

・ Dai-ichi Reactors 5 & 6•
shared power, but unable tosupply power to Reactors 1 - 4
・ Delay to supply andinsufficient number of power
supply vehicles

・ Complete darkness in themain control room due to DC
power outage
・ Instant loss of parametermonitoring and control
functions

Measures / Lessons

・ Increase number and varietyof alternative DC power
supplies for maintaining
monitoring functions.

130
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Power outage...

Extremely Confidential

Power Outage (Fukushima Dai-ichi, Dai-ni, Higashi Dori, Onagawa, Tokai Dai-ni) - 1
Cause・ Loss of power fromearthquake and after
shocksEvent / Issue

Measures / Lessons•

External power: On 3/11, Fukushima Dai-ichi, Tokai Dai-ni, and Higashi Doriexperienced external power outage. On 4/7 external power in Higashi Dori was cut-off
again (emergency DG automatically activated in both cases). For defense-in-depth, it’s
important to have power transmission equipment that doesn’t rely on emergency DG,
especially in Higashi Dori where external power outage occurred twice in 1 month. The
vulnerability of the power transmission system was evident. Earthquake caused thepower outage in both cases, so it’s recommended that the power transmission network be
expanded, and earthquake resistance improved on switching stations and substations .

・ Expand power supply network
・ Reinforce earthquake resistance ofpower substation facilities andswitching station•
・ Failure of theemergency DG,
seawater coolant pumps,
and cooling systemcaused by the tsunami
and flooding.

Emergency DG Power: Emergency DGs stopped working either from flooding in the DG
or in the seawater pump facility in Fukushima Dai-ichi, Dai-ni, Onagawa, and Tokai
Dai-ni.

・ Identify how the floodwaters
entered the Emergency DG room andimplement countermeasures
・ Flood prevention and reinforcementof water protection of coolant pump・ Secure spare parts for emergency
DG

・ No anticipation orprocedure for handlinginstant DC power outage
and alternative power
backup.

•

DC power: DC power supply was lost due to flooding in Fukushima Dai-ichi. Loss of DC
power greatly effected the field environment. Measuring instruments and operation ofhigh pressure cooling systems stopped working. This lead to the critical accident. This
event has made us reaffirm that DC power supply is the most important equipment.

・
・
・
・

•

The tsunami flooding damaged the power paths such as M/C and P/C in Fukushima Daiichi and Dai-ni. In other plants M/C and P/C stopped functioning from partial loss of
power. In both cases, crucial responses such as cooling and venting of the reactor wereaffected .

・ Loss of power path suchas M/C and P/C due toflooding.

Reconsider location of DC power
Flood defense measures
Upgrade battery capacity
Secure alternative DC power, DC
power supply vehicles, and meansof battery charging

・ Consider relocating power panel tohigher area
・ Prepare power supply vehicles,
cables, connection terminal systems,
and connection route・ Equip specific procedures and131
reinforce training

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Power outage...

Extremely Confidential

Power Outage (Fukushima Dai-ichi, Dai-ni, Higashi Dori, Onagawa, Tokai Dai-ni) - 2
Cause・ Insufficient number of power
supply vehicles.
・ Delay in arrival of additional
vehicles.
・ Insufficient backup batteries,
temporary orders, compact
generators, etc.

Event / Issue

Measures / Lessons•

Power supply vehicles: If necessary load for power supply vehicles had
been predetermined, sufficient amount of units secured, and vehicles
arrived quickly, the result could have turned out better, especially inFukushima Dai-ichi.

・ Increase number of permanent power
supply vehicles (multiplex) (DC, AC, mix)
・ Prepare emergency kit for power
blackout (batteries, lights, compact
generators, fuel, cables, etc.)
・ Create manuals for aforementioned
items, and conduct training.

・ Not prepared to restore power, •high pressure cooling system,and depressurization functions
under severe and adverse
environment. Insufficient AM
countermeasures.

Emergency DG, all AC power, DC power, and emergency seawater
pumps ceased to function instantly from the tsunami flooding inFukushima Dai-ichi. Restoration process was conducted in an
overwhelmingly adverse environment. It was extremely difficult tomaintain the high pressure cooling system and to switch to low pressure
cooling (preparations, etc.). This chain of events is one of the maincauses of the hydrogen explosion that occurred in the plant.

・ Reinforce training simulating worst
case scenario. (Conduct continuous
training repeating the following: set
target restoration time, record actual
completion time, and evaluate results.)

132
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Cooling Function...

Extremely Confidential

Loss of Seawater Cooling Function (Fukushima Dai-ichi)
Cause

Event / Issue

Measures / Lessons

・ Secure emergency DG
・ Power sharing function
・ Reconstruct seawatercooling system that
doesn’t consume time•

The tsunami didn’t reach the Fukushima Dai-ichi Unit 6 air-cooled emergency
DG. Power was shared between Reactors 5 and 6, and supplied to the RHRpumps. By preparing a temporary seawater pump and power supply vehicle, they
were able to reconstruct the seawater cooling system and achieve cold shutdown.
Learning from this experience, connection route should be defined (i.e. in the
manual), and training conducted periodically to enable prompt response to suchsituations.

・ Reaffirmed the importance of
emergency DG and the power
sharing capabilities
・ Conduct periodic training
simulating similar events

・ Vulnerability ofemergency DG (watercool) cooling function(seawater pump, motor,etc.).

•In Fukushima Dai-ichi Reactors 1 – 6, all seawater pumps stopped functioning
due to the flooding by the tsunami resulting to loss of seawater cooling system(ultimate heat sink).
Although the emergency DG was also flooded and malfunctioned, even if it did
survive the tsunami, the DG would still have stopped with the malfunction of thecooling equipment (seawater pumps, motors, etc.). When emergency DG stops, achain reaction causes the ECCS pump to stop working as well.

・ Secure seawater cooling system,
backup water pump, power
supply, fuel, etc.
・ Prepare air-cooled DG line (notdependent of seawater)
・ Consider using motor with strong
water protection

・ Loss of seawater cooling
function•

Fukushima Dai-ichi 1 – 3 was not able to achieve cold shutdown due to loss ofseawater cooling function.

・ Same as above.

133
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Comparison with others...

Extremely Confidential

Comparison with other Power Plants
Cause

Event / Issue

Measures / Lessons

・ Retained external power・ Retained main control room
function・ Secured time for recovery
with the high pressure
cooling system.
・ No delay in the restorationand operation of seawatercooling system.

・Plants that were able to secure external power supply achieved cold shutdown.
－ Fukushima Dai-ni was able to secure 1 external power system.
－ They lost DG and seawater cooling system from the tsunami but with theexternal power they were able to maintain main control room functions. With DC
power, they were able to maintain high pressure cooling by using the RCIC andthe SR valve.
－ This bought them time to restore the emergency seawater pumps and power
the necessary pumps.

・ Reaffirmed the importance of
external power.
・ Reaffirmed the effectiveness of
AM when external power and DC
power are available.

・ Same as above.

•

In the Onagawa power plant, Reactors 2 & 3 were able to secure 1 external
power system which allowed them to maintain the seawater cooling system andsucceed in implementing standard cold shutdown.
－ Unit 1 lost external power, and DG was activated.
－ Achieved cold shutdown by maintaining seawater cooling function.
Cold shutdown can be achieved by maintaining power and securing seawater
pump functions.

・ Same as above.
・ Importance of seawater cooling
function.
・ Secure alternative equipment
when main equipment is damaged.
・ Affirmed the importance ofrecovery process training.

Partial flooding of seawater pumps caused emergency DG to stop in Onagawa
Unit 2, and Tokai Dai-ni. (2 DG units in Onagawa Unit 2, and 1 unit in Tokai
Dai-ni were lost.)－ There’s no denying that the situation could have been the same as with
Fukushima Dai-ichi 1 – 3 if all external power and DG had gone out at the sametime.

・ Plants that achieved cold
shutdown shouldn’t blindly
celebrate their successful
recovery. They should
acknowledge the potential risks
they faced and review thenecessary countermeasures andtraining.

•

・ Same as above.

•

134
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Cooling Function...

Extremely Confidential

High Pressure Cooling System - 1
Cause

Event / Issue

Measures / Lessons

・ Loss of all DC power・ Unable to read sensors
・ Failed main control tower
function•

1F Unit 1: Parameter data: The facility lost DC power right after theearthquake and tsunami. Without power, measurement instruments
weren’t functioning so it was impossible to acquire important parameterssuch as the core water level. As a result, operators weren’t able todetermine the actual situation and make appropriate decisions. They had
already started making the wrong decisions in handling the high pressure
cooling system.

・ Countermeasures for main control room
power outage.
・ Flood prevention to DC power supply(location, water seal, battery water
protection)
・ Secure backup batteries (battery, DC
power supply vehicle)

・ Loss of all AC/DC power・ Failed IC valve operation•

1F Unit 1: IC cooling and depressurization: Similarly, without AC/DC
power, operators were unable to adjust the valves of the high pressure
cooling system (IC).
As a result, operating the high pressure cooling system was almost
impossible. It can be inferred that water injection and depressurization
failed. Our theory is that the core’s water level was decreasing whiletemperature and pressure kept rising and damage is estimated to havestarted 3 hours after the tsunami.

・ Restore AC & DC power within 2 hours?
・ In addition (to AC), allow direct valve
adjustment?
・ Consider valve adjustment mechanismthat doesn't rely on electricity (manual &auto).

・ Loss of all AC/DC power•・ Failed HPCI valve operation

1F Unit 1: HPCI water injection and depressurization: Similarly, without
AC/DC power, operators were unable to adjust the valves of the HPCI
system and failed to perform water injection.

・ Same as above.

・ Incompleteness of multiplex •defense in the AM
・ Delay in depressurizationand preparation for low
pressure cooling

1F Unit 1: AM ineffective due to unavailable measurement data and highpressure cooling system: With the complete AC/DC power outage, theplant didn’t have enough time to prepare for transition from high pressure
to low pressure cooling according to the AM (+α expertise of site
personnel) because everyone was busy securing AC power (power supply
vehicle), securing DC power (car batteries), vent line setup (manual), lowpressure coolant injection setup (fire truck, hose, water supply for fire
extinguishing), etc.

・ Design AM that anticipates instant andconcurrent loss of entire AC and DC
power (unable to recharge batteries due
to flooding).

・ Activation of RCIC

Effectiveness of the RCIC: Unit 1 lost its IC system and wasn’t able tomaintain high pressure cooling.
But in Unit 2, RCIC was activated and continued working. It is believedthat the RCIC kept the pressure in the S/C within the estimated limit of
0Ka (abs) for 3 – 4 days after the tsunami, before the containment vessel
was eventually damaged.

・ Reaffirmed effectiveness andimportance of maintaining high pressure
cooling system.
・ Important to provide procedures andtraining for preparing and setting up low
pressure cooling system while
the high
135
pressure cooling system is working.

•Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Cooling Function...

Extremely Confidential

High Pressure Cooling System - 2
Cause

Event / Issue

Measures / Lessons

・ Fukushima Unit 1hydrogen explosion•

1F Unit 2: Set up of high pressure cooling system incomplete – repeated interruption
and damage to the water injection line from hydrogen explosion (3/12): Response
unit completed the preparation for backup water injection to the core, and connected
the power supply vehicle to a working P/C, but the cables and the power supply
vehicle were destroyed when Unit 1 exploded on 3/12 and everything had to be set
up from scratch again.

・ Review the risks involved inoperating multiple plants
・ Absolute prevention of hydrogen
explosion・ Same as above. (Unit 3)•

1F Unit2: Same as above (3/14): The response unit was able set up a seawater
injection line using fire trucks and hoses, but the hydrogen explosion in Unit 3 on
3/14 destroyed the fire trucks and hoses and everything had to be set up from scratch
again.

・ Same as above.

・ Frequent aftershocks•

1F Unit 2: Effect of aftershocks: In parallel with previous items, repeatedaftershocks interrupted the setup of injection line, and as a result the response unit
was not able to execute in time.

・ Redesign AM and training
anticipating overwhelmingly poor
environment

・ Incomplete coverage in
the AM•

1F Unit 2: Incomplete coverage in the AM: As a result of the events above, theyfailed to make any effective actions to maintain high pressure cooling except for the
RCIC which survived through tsunami.

・ Same as above (including instantloss of power, cooling function,and seawater circulation system,
as well as frequent aftershocks)•

1F Unit 3: Importance of DC power and Effectiveness of RCIC:DC power (DC125V Main bus board 3A and 3B) survived the earthquake andtsunami, and it was used to power the high pressure system (RCIC or HPCI).
However, the plant wasn’t able to secure backup power, and DC power was
depleted up after 35 hours from activation of RCIC. At this point, HPCI was alreadyhalted. Consequently, the plant failed to decrease the reactor’s pressure and recover
the water level. (We were able to verify that the batteries were depleted so ourtheory is that this is the reason the system stopped.)

・ Reaffirmed importance of DC
power and RCIC・ Secure additional power sources;
reinforce and conduct training•

1F Unit 3: Effectiveness of HPCI: The batteries depleted on 3/12, at 11:36, causing
the RCIC to stop. HPCI was activated on the same day at 12:35. During this periodof time the core pressure dropped from 7.53MPa to 0.58MPa, but went back up to
7.4MPa on 3/13, 2:42, when the batteries for HPCI were depleted (cause of HPCI
halt is believed to be depleted batteries since the batteries were found andconfirmed).

・ Same as above.

・ Maintain DC power・ Failed to secure
alternative powersource during thisperiod・ Use of car batteries
・ Activation of HPCI

Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

136

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Cooling Function...

Extremely Confidential

High Pressure Cooling System - 3
Cause

Event / Issue

Measures / Lessons

・ AM incomplete (Secure extra
DC power and backup power)・ Same as above. (Devise
countermeasures to events
when DC power is lost fromflooding and batteries can't
be charged.)•

1F Unit 3: AM incomplete (Secure extra DC power supply or backup power supply):
1F Unit 3 was the only reactor among Reactors 1 - 4 that retained its DC power
supply. However, looking at the chronology, there is no evidence of additional
backup power source being secured before the DC power supply was consumed(though used car batteries from employees’ cars and other sources after HPCI
stopped). Furthermore, there is no trace of reserve DC power batteries stored in thereactor building or in the seismic isolation tower. Storing of reserved batteries for
emergency, such as in this case, may not have been specified in the AM (= it seems
that they have no other measures than to restore the AC power within 8 hours(battery life) and then to recharge DC batteries when the AC power is restored). As aresult, high pressure cooling systems such as the RCIC and HPCI had to stop
prematurely.

・ AM incomplete (No defensein-depth for DC power?)•

1F Unit 3: AM incomplete (defense-in-depth for DC power): This is related to theprevious item. It seems that AM provides only one solution for high pressure system(RCIC/HPCI) power recovery. It only seems to “restore AC power within 8 hours(the life span of the DC batteries) and recharge the batteries with the AC power.”This leads to the conclusion that the facility has weaknesses in its defense-in-depth
for DC power.

・ Restoration process under
unexpected field condition(not covered by AM)•

1F Unit 3: AM ineffective (core reactor scram & loss of AC power): Of all units of
1F, it is believed that only the event in Unit 3 was within the scope of the AM
manual (earthquake, AC power outage, core reactor scram, DC power utilization(8hrs)). However, Unit 3 was not able to achieve cold shutdown. Although they wereable to prevent damage to the core for 36 hrs by powering the high pressure coolingsystems (RCIC and HPIC) with the DC power supply, they were not able to “restore
AC power, depressurize the reactor core, and make the transition to low pressure
cooling” as indicated in the AM.

・ Reserve extra DC batteries(multiplex - since batteries can nolonger be charged if flooded)

・ Same as above.
・ Update AM and training to include
responding to instant loss of all
DC power supplies from flooding(batteries can’t be recharged).

・ Same as above.

137
Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Vent...

Extremely Confidential

Ventilation System (Depressurization with SR valve operation) - 1
Cause

Event / Issue

Measures / Lessons

・ Loss of all AC & DC
power
・ SR valve malfunction•

1F Unit 1: SRV non-functional due to loss of DC power: The SRV (safety release valve)
which is used by the high pressure cooling system stopped functioning due to loss of all AC
and DC power from the earthquake and tsunami. In Unit 1, the SRV didn’t work at all.
Because of this, workers decided to reduce core pressure by using IC. However, partially
due to the adverse environment the IC didn’t function as designed. At the end, site workers
failed in reducing the core pressure, and it continued to build. (Regarding the decrease in the
nuclear reactor pressure, SR valve may have been stuck, and steam may have leaked fromthe SRV flange section gasket due to the rise in pressure vessel temperature. This may have
reduced the pressure in the nuclear reactor, but at this point these are just conjecture.)・ Same as above.

•

1F Unit 2: SRV non-functional due to loss of DC power: Same as above. (＝＞ P/C (2A, 2B,
2C, 2D) were working, but like in Unit 1 the entire battery room, where the DC batteries
were stored, was flooded. Without power the SRV didn’t function.) When the RCIC
stopped, they decided to depressurize the nuclear core reactor to perform lower pressure
water injection, so workers used spare batteries to power the SRV to perform thedepressurization operation.

•
・ Same as above.
・ Delay in securing sparebatteries
・ Delay in setting up water
injection line for fire
truck?

1F Unit 3: Delay of depressurization (SRV) due to lack of batteries.: With DC power (3A,
3B) available, plant workers followed the manual and cut unnecessary power consumption
to buy more time for RCIC/HPCI to work. The batteries provided power for approximately
35 hours until the HPCI was tripped. After the HPCI stopped working, workers attempted todepressurize the reactor to inject water via fire truck hose, but weren’t able to operate theSRV because there was no power. So they collected the car batteries from the employees’cars, and at 3/13, 9:08, they were finally able to operate the SRV and depressurize thereactor (HPCI stopped at 2:42, 3/13; pressure relieved 6 hours after). Later at 9:25 the fire
trucks arrived and started the alternative water injection (one truck from 1F 5 & 6, and one
more from 2F).

・ Multiplex DC power (extra batteries,
and allow charging from battery
vehicles and AC power supply
vehicle)・ Improve water protection of DC
power supplies (batteries) (safer
storage location or water seal of
the batteries themselves )・ Store spare batteries, and optimize
installation time.
・ Increase number of response unit
members and conduct training toachieve the above.
・ What about using a mechanismthat doesn‘t rely on DC power tooperate the SRV?

・ Same as above.
・ Upgrade regular DC power supplies(extended battery life)
・ Reduce the time spent for setting
up water injection line for fire
trucks.

138
Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Vent...

Extremely Confidential

Ventilation System (Depressurization with SR valve operation) - 2
Cause

Event / Issue

Measures / Lessons

Secured external power
Secured DC power
RCIC was functioning
Set up line for low
pressure cooling•

2F Unit 2: Successful case in pressure vessel depressurization with
the SRV: 2F Unit 2 lost its emergency DG from the flooding oftsunami, and its ultimate heat sink. However, the facility was able
to receive external power, and the power panels and DC power
supplies were working. They were able to maintain the water levelof the nuclear reactor with RCIC, which bought time for setting up
the line for the Make-up Water Condensate system (MUWC). Aftersetting up MUWC, operators adjusted the SRV, depressurizing thereactor as planned. After that, they performed low pressure coolant
injection and achieved cold shutdown => Importance of external
and DC power.

・ Reconfirmed the importance of the following:－ External and DC power－ RCIC (with power)－ Low pressure cooling system (with power)

・ Failed to secure power・ Failed in high pressure
cooling (from lack of
power)・ Failed to depressurize
(SRV)

•

1F Units 1-3: Limitation of AM (Especially with risks in failinghigh pressure cooling): Nuclear reactor depressurization operation
was performed on Units 1-3 after the high pressure cooling stopped
working. They weren’t able to set up the transition to low pressure
cooling while the high pressure cooling system was running. It isbelieved that the delay was partially caused by the unprecedented
adverse field condition.

・ Same as above.
・ Revise AM (integrate unexpected incidents
learned from this event)・ Same as above (Provide judgment base fordetermining plausibility of cold shutdownwith the standard operating procedure. Also
provide timeframe as to when to start setting
up the low pressure system.)・ In addition to the previous items, provide
alternative action guidelines (the guideline
should aim to prevent the worst casescenario instead of aiming for perfection. For
example, prevention of hydrogen explosion,
venting reactor building, seawater injection,
rapidest depressurization using IC, etc)
・ Maintain worker’s ability to respond to
emergency situations with regular training.

・
・
・
・

139
Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Vent...

Extremely Confidential

Ventilation System (PCV vent) - 1
Cause

Event / Issue•
・ AC & DC power outage
・ Complete darkness inside thebuilding
・ Increasing dosage rate in thebuilding with the progressionof core reactor damage
・ Frequent aftershocks (required
temporary evacuation)・ Lack of pressure from aircompressor
・ Delay in arranging andtransport of equipment such as
air compressors and adaptors.
・ Delay in venting containment
vessel・ RD operation pressure

・ Same as above.

••

Measures / Lessons

1F Unit 1: Delay in PCV operation: On 3/12 (00:06), orders were given out to prepare for ・vent operation, when workers realized that D/W pressure may have exceeded 600k Pa abs.
However, the actual vent operation was performed at 14:30 on that day. The operation
・started at 09:04 but took approx. five and a half hours to complete. The reasons are:–No power to the valve (no AC & DC power)–
Complete darkness inside the building due to blackout (except for main control
・
room)
–
Increasing dosage rates paralleled with the progression of core reactor damage
・(especially at basement 1)–
Orders to stop field work due to frequent aftershocks–
Work halted until evacuation of neighboring residents completed. Insufficient・means of communication for progress updates.
–
Lacking means of communication between main control room and field workers
inspecting the vents–
Failed in vent release due to lack of pressure from air compressor–
Time consumed by arranging for temporary air compressor, delivering adapters,
and transporting.
Although they were able to vent the containment vessel and confirm the drop in pressure, thereactor building exploded approximately an hour after.

1F Unit 2: S/C vent failure due to high operation pressure of Rupture Disk (RD): In theinitial attempt to vent the S/C, the workers had to overcome an obstacle in which thecircuit board for energizing the solenoid valve was dislodged by the explosion in Unit 3.
On the same day around 21:00, workers had completed constructing all vent lines except
for the RD, but even with the D/W pressure exceeding its max capacity of 427 Pa gage
(530k Pa abs), the pressure in S/C was not enough to move the RD. At 23:35, theydecided that the operation was a failure and had no choice but to switch to D/W venting.

Secure power (DC, AC, and backup
power supplies)
Confirm availability of emergency
lights (installed in reactor building,and portable lights for field work)
Secure emergency communication
methods
Secure extra compressors andadaptors
Change the ventilation system.
Ventilation should be performed
even in the event of SBO (a systemthat allows ventilation operation
remotely with reserved power(manual release as a last resort))

・ Review RD operation pressure.
・ Confirm reason for setting highpressure configuration to open the
disk.
(The operation pressure was set to a little
under 2 times the designed pressure value.
This was done with the hopes of preventing
the release of radioactive materials. But thisaction may have contributed to hydrogendensity exceeding 4% when hydrogen(generated due to fuel damage) leaked out
from the containment vessel.)

1F Unit 2: D/W vent failure: On 3/15 (apprx. 00:02 ) after failing the vent operation in theprevious issue, the attempt to open the D/W vent commenced. The preparation of the ventline was completed on 3/15, at 0:02. Although the D/W pressure shifted with the averageof 750k Pa abs, after a few minutes the vent was confirmed to be shut. Around 6:00 - 6:10
・ Consider replacing RDs with valvethe same day, it is estimated that severe damage to the PCV had occurred, judging fromoperated ventilation system.
the record that the S/C pressure was 0K Pa. Ventilation failed.

140
Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Vent...

Extremely Confidential

Ventilation System (PCV vent) - 2
Cause

Event / Issue

Measures / Lessons

・ Insufficient pressure
from air compressor
・ Faulty solenoid valve
・ Delay in vent line setup•

1F Unit 2: Delay in vent line setup due to lack of pressure from air compressor
and faulty solenoid valve: After the Unit 3 explosion on March 14 (11:01),
workers attempted to open the S/C vent valve (large AO valve) but failed. The
pressure from the air compressor wasn’t enough. It is postulated that the AO
valve couldn’t be opened in processes with the same line up due to a faultysolenoid valve.

・ Consider a vent system that
doesn't use air pressure (prepare
temporary compressor, fieldenvironment management, line
construction that allows
connection; change to a valvethat allows manual operation).

・ Complete darkness
・ Hot and humid work
environment
・ Difficulty in vent line
setup

•

1F Unit 3: Slow W/W vent set up progress due to the dark, hot and humid
work environment: On March 12, at approximately 4:50 (RCIC still running)
after energizing the S/C vent solenoid valve with the main control room’s
compact generator, the shift workers went to the torus room to confirm if thevalve was open. However, they found that the room was in complete darkness,and temperature and humidity was high because of steam coming out from theSR vent valve of S/C. The work environment was tough and they were making
very slow progress. Also on March 13 around 11:00-12:00, workers once again
entered the torus room in an attempt to lock the S/C vent valve (AO valve), butweren’t able to complete the task due to increased temperature and vibrationfrom the SR valve.

・ Review and reconsider positionof the valve141
Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Vent...

Extremely Confidential

Ventilation System (PCV vent) - 3
Cause

Event / Issue

Measures / Lessons

・ Delay in air cylinder
replacement•

1F Unit 3: Delay due to air cylinder replacement: On March 12, at approx.
5:23, workers attempted to open the S/C vent (AO vent) but failed. Second
attempt, after replacing the air cylinder, was successful.

・ Secure extra air cylinder for
operating vent valve.
・ Include replacing of air cylinder in the
training.

・ Reduced pressure of air
cylinder due to leak•

1F Unit 3: Problem keeping the vent valve open due to a defect in the air
cylinder: On March 13, after vent was successfully performed, the S/C ventvalve (AO large vent) was closed again at approx. 11:17 due to a leak in
the air cylinder.

・ Reinforce the joints and connectionsof the air cylinder (ensure reliabilityof air supply line by improving its
safety, or secure backups (multiplex)).

・ Insufficient air pressure
supplied to the large
valve
・ Energizing of solenoid
valve unstable•

1F Unit 3: Difficulty maintaining air pressure for operating the large valve
and energizing the air supply line’s solenoid valve: Although Unit 3
succeeded in venting, workers were having difficulty keeping the vent open
(or failed). The postulated reason is a problem with the air pressure used tooperate the large valve, and a problem the with air supply line’s solenoid
valve (unable to energize consistently). This seemed to have occurred 5times after the explosion.

・ Review the vent mechanism andimprove its ability to maintain openstate (strengthen air supply line, or
secure backups (multiplex)).

142
Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Cooling Function...

Extremely Confidential

Low Pressure Cooling Function - 1
Cause•
・ Difficulties and delays insupplying water via fire
trucks・ Trouble with the dieseldriven fire pump・ Damage to fire hydrant
from earthquake andtsunami, and filtered water
was gushing out
・ Time consumed searchingfor alternative water source
・ Not enough fire trucks
・ Fire truck mobility issues
due to adverse environment
・ Delay in setting up water
injection line from fire truck
・ Insufficient water injection
capacity of fire trucks

Event / Issue

Measures / Lessons

1F Unit 1: Difficulties in supplying water from fire truck, and delay incommencing: As early as March 11, 17:12, instructions to consider water
injection from the fire line and fire trucks were given. However, the dieselgenerated fire pump was having trouble, so the decision was made to inject water
directly from the fire line, instead of using the fire truck (March 12, 1:48). Fromthe previous item, setting up water injection line from fire truck (loading water tofire truck, transport the truck to reactor building, connecting the truck with water
protection system line) was time consuming. The injection process started at 5:46
(3/12).
The main reasons are as follow:
–
–
–
–
–

–

–

Trouble with the diesel-driven fire pumpDamage to fire hydrant from earthquake and tsunami - filtered water was
gushing out (valve closed manually to stop water outflow)
Time consumed searching for alternative water source (after surveying thesite, they discovered that fire protection tank can be used)
Not enough fire trucks (of the 3 trucks, 1 was damaged by the tsunami, 1
was at Units 5 & 6 and was unable to transfer due to liquefaction)
Trouble moving the fire trucks due to adverse environment (gasoline tankblocking the road, main gate stuck due to blackout. Workers had to destroy
the lock on the gate between Units 2 and 3 to create passage)
Delay in setting up water injection line from fire truck (ordering for fire
trucks, transport to reactor building, connecting to fire protection systemline)
Insufficient water injection capacity of fire truck (1000 liters per payload)

On March 12, filling of water to the reactor started at 5:46 and finished at 14:53(total of 80 tons of water). At first they were only able to fill 1000 liters at a time,
but later were able to fill water continuously. Before then the fire truck had tomake laps for refills. Fast-progressing events required a more efficient response.

Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant・ Reinforce and add more backup
water sources (install large fire
protection tank)・ Increase number of fire trucks andhoses
・ Review posting of fire trucks
・ Secure predetermined route forfire trucks (for smooth transport
during blackouts)
・ Secure backup power supplies andpumps; upgrade fire truck; etc.
・ Investigate cause of the dieseldriven fire pump problem, andcome up with a countermeasure.

143

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...Cooling Function...

Extremely Confidential

Low Pressure Cooling Function - 2
Cause

Event / Issue

Measures / Lessons

・ Problem with the fire
protection tank’s
design・ Inefficient water
injection

・

1F Unit 1: Inefficient water injection from the fire protection tank: Laps had to bemade in loading fresh water from the Unit 3 fire protection tank and transportingit to the Unit 1 fire protection tank. The fire protection tanks only have one hoseconnection, so workers had no choice but to remove the injection hose andinterrupt the injection each time it needed to be refilled.

・ Review the design of the hoseconnection of fire protection tank・ Delay in boric acidinjection (SLC)•

1F Unit 1: Delay in setting up boric acid injection (SLC): Concurrently with thewater injection process (via fire truck), power restoration (via power supply
vehicles) and boric acid injection (SLC), pump restoration processes wereongoing. Preparation for boric acid injection was completed on March 12 (15:36),
but the plant building exploded right after it was completed (15:36). SLC pumpcables and the high pressure power supply vehicle were destroyed, renderedunusable.

・ Secure backup power supplies(high pressure power supply
vehicle)・ Supply more cables and fire trucks

・ Same as above (due toexplosion)•

1F Unit 1: Delay in boric acid injection (SLC): After the explosion on March 12(19:04), seawater injection through the fire protection line by fire truck
commenced. Injection of seawater mixed with boric started later at 20:45.

144
Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...General...

Extremely Confidential

General lessons - 1
Cause

Event / Issue

Measures / Lessons

・ Difficulties in executing •countermeasures due tooverwhelmingly
unexpected events, andsevere accident

General AM: Overlaying difficulties and delays in executing countermeasures:
As part of accident management the low pressure water injection had beenenhanced, and manuals had been distributed. The actual work fieldenvironment was adverse, and extra time was required to restore power andperform low pressure water injection. They were unable to contain thesituation.

・ Improve the AM training to respond to
more specific situations, and continue
the training on a regular basis (effects ofthe earthquake and tsunami like this,setting of specific target completion
times of actions, confirm the timerequired, accrue know-how)・ Insufficient daily training •of AM actions in
anticipating scenarios ofprevious item.

AM: Anticipate accidents at night time / on holiday: The field response of thisevent was difficult and slow because of the adverse field environment. Debris
was scattered by the earthquake and tsunami, and much of the work had to bedone during the night.

・ Practical training simulating power
outage during night / holidays
・ Improve and standardize night time
visibility of valves and gauges (use offluorescent paint, etc.)•
・ Risk of sharing water
source and injection line
for multiple purposes

Water source & water line: Risk of sharing for multiple purpose: We learned
the importance of fire protection system from the incident in KashiwazakiKariwa Plant when the transformer in Unit 3 caught fire during the Chuetsu
offshore earthquake.
As for this event, the M/C power panel in Onagawa Unit 1 caught fire. There
was no fire in Fukushima Dai-ichi, which allowed them to use the powerprotection line and water source for lower pressure water injection. But if a fire
had occurred, it can’t be denied that it could have caused further problems in
addition to plant water injection.

・ Consider segregating water sources・ (Multiplex) Increase number of water
source for the most important ones (takeinto account water source for fire
response as well)・ Risk of placing multiple •plants in the same
location.
・ Difficulties of handlingsevere accidents
simultaneously occurringin multiple plants. The
plants were not prepared
for this sort of situation.

General AM: Risk of operating multiple plants in the same location: Nuclear
Emergency Response Headquarters of Fukushima Dai-ichi Units 1 – 4prioritized responding to Unit 1 because it wasn’t able to maintain highpressure cooling with IC. Units 2 & 3 weren’t given priority since RCIC highpressure cooling was working. The decision was the right one at that time.
However, looking at the fuel rod damage chronology of Units 2 & 3, theywould have been able to avoid the worst-case scenario if they had been able toset up the low pressure cooling system before the DC power of RCIC wasdepleted.

・ Identify the issues with the field
response system・ Identify the problems encountered due
to severe accidents simultaneously
occurring at multiple plants
・ Reflect the previous two items in the
manual and conduct training.

Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

145

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...General...

Extremely Confidential

General lesson - 2
Cause

Event / Issue

Measures / Lessons•
・ Rupture-disk pressure
setting in Dai-ichi Unit 2 is
too high.

Dai-ichi Unit 2: Difficulties in venting R/D (required pressure was high): Dai-ichi
Unit 1 and Unit 3 succeeded in venting the containment vessel suppression
chamber (S/C). However, the same ventilation in Unit 2 failed to open even withthe drywell pressure exceeding maximum capacity. The S/C pressure wasn’t
sufficient to move the rupture disk (R/D). After that, a system to release the drywellpressure was set up, but S/C was damaged and the ventilation process was once
again unsuccessful.

・ Reconsider the pressure
settings of the rupture disk
・ Regular inspection andreplacement of rupture disk

・ Relation between the PCV •vent and hydrogen
explosion・ Unclear mechanism ofHydrogen leakDai-ichi Units 1 & 3: Relation between the containment vessel vent and hydrogen
explosion: Hydrogen explosion occurred in 1F-Unit 1 and 3 one to two hours after
successful venting of PCV. The hydrogen produced inside the reactor by molten
fuel may have transferred and filled the containment vessel when the SR valve wasoperated, and released steam to the suppression pool. The hydrogen then probably
leaked to the reactor building through the containment vessel’s routing channels
and vent line, or back flowed from the SGTS line connected to the exhaust stack.
And finally when the hydrogen accumulated beyond the combustible limit, theexplosion occurred. In this project we have taken into account the possibility thatthe hydrogen accumulation speeded up by the ventilation of PCV. Actual details,
and cause and effect are still unclear, so we are hoping that it will be solved.

・ Identify the leak path ofhydrogen into the reactor
building
・ Devise countermeasures forhydrogen leak・ Review vent in post core
meltdown (nitrogen sealing,
operation pressure)・ Prevention of hydrogenaccumulation in reactor building
and exhaust system

・ Extended external power
outage・ Extended DC power
outageGeneral: Risk of extended external and DC power outage: The loss of external
power and of emergency DG, and malfunction of seawater cooling system occurredin Fukushima Dai-ichi, Dai-ni, Onagawa, and Tokai Dai-ni. Only Fukushima Daiichi lost its DC power as well. By securing external power, the plant was able toretain its high pressure cooling system, buying time to restore the seawater pumps
and motors for the low pressure cooling system, and deploy power supply vehicles.
Prolonged station blackout depleted the DC power, and meant loss of hope forrestoring the plant. Without the seawater pumps the DG won’t function. This
increases the urgency to restore external power for the seawater pump.

・ Increase number of temporary
DC and AC power supplies
・ Prepare connection devices foralternative power supplies
・ Reinforce training•

Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

146

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Lessons...General...

Extremely Confidential

General lesson - 3
Cause

Event / Issue

Measures / Lessons

・ May not have considered therelation between vent
operation pressure andhydrogen explosion.
・ May have lack ofunderstanding of hydrogen
explosion risks, and lack ofcountermeasures in AM.

•

Fukushima Dai-ichi (General): Relation between the mechanism ofhydrogen explosion and vent operation: Compared to other electriccompanies, TEPCO had configured a higher value for the vent operatingpressure. They thought that this will further decrease the chance of
releasing radioactive materials to neighboring residences. However, thisdecision may have been one of the main reasons the hydrogen explosion
occurred. It is postulated to have caused massive build up of hydrogen in
the containment vessel. Further, regarding the hydrogen explosion there is
no record of a backup plan in the response chronology of Unit 1. We
assume that this accident was not expected by TEPCO.

・ Identify the mechanism of hydrogen
explosion (leakage path,accumulation path, ignition cause,etc.)
・ Prevent hydrogen accumulation(detector, reactor building vent, etc)
・ Verify the relation between the ventand hydrogen explosion
・ Reflect changes to corresponding
manuals・ Loss of function as main
control tower due to SBO•

Fukushima Dai-ichi (General): Effect of the incomplete main control room
functions: The station blackout disabled the instrumentation and took away
the indicator monitoring capability from the operators. Without thiscapability, it’s impossible to plan the next move. Additionally, when the
nuclear reactor is at high temperature, it’s doubtful whether the data givenby the measuring instruments powered by temporary supply is accurate.
Without indications and data, operators will start to fear, which affects theirability to make proper judgments. Operators must be equipped in order tobe able to make proper judgments.

・ Secure main control room lights, fieldenvironment, measuring instruments,
etc. (power, lights, work clothes,dosimeters, furniture)
・ Review AM procedure and reinforce
constant daily training
・ Apply remote measuring instruments•
・ Hydrogen explosion
・ Leak of radioactive materials
from explosion

Fukushima Dai-ichi (General): Radiation leaked to the environment when
Units 1 – 4 exploded, causing enormous damage to the local community.
Today, there are many that suffer from the effects of land contamination
and radiation exposure. The spread of Cesium 137 (from the explosion) has
a long term effect, and is an especially big problem. The most important
things are to prevent a hydrogen explosion at all cost, prevent the spread ofradioactive materials, and to minimize those effect.

・ Prevent hydrogen explosion
・ Prevent leak/release of radioactive
material(Consider installing filter vent)Note: 1F = Fukushima Dai-ichi power plant, 2F = Fukushima Dai-ni power plant

147

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Lessons
LessonsLearned
LearnedandandSafety
SafetyMeasures
Measures－－Safety
SafetyMeasures
Measures－－

148
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Secure power supply - 1
PurposeSecureSecurepower
power
Securecontrol room
functions
Secure highpressure
cooling system
Secure ventfunction
Secure lowpressure
cooling system
Secure ultimate
heat sink
Prevent hydrogen
explosion /radiation leak
Disaster
response manual/ infrastructure, etc.

Safety Measure (Prevention)

Safety Measure (Impact mitigation)

Secure external DC power supply
Secure external DC power supply

Secure external DC power supply
Secure external DC power supply●
Improve water protection and pressure resistance of switching stations.
●Improve water protection and pressure resistance of switching stations.
● Switching stations should be located on elevated areas, or sea-walls should be built● Switching stations should be located on elevated areas, or sea-walls should be built
to protect the equipment from tsunami.
to protect the equipment from tsunami.
● Evaluate and improve earthquake resistance of switching stations, transmission line
● Evaluate and improve earthquake resistance of switching stations, transmission line
towers and power plants. Furthermore, include earthquake resistance in the design
towers and power plants. Furthermore, include earthquake resistance in the design
requirements.
requirements.
●
Minimize frequency of external power outage by drawing multiple power lines●
Minimize frequency of external power outage by drawing multiple power lines
from the substation (minimum of two separate lines), or connect external power offrom the substation (minimum of two separate lines), or connect external power ofall plants in a network for all the plant to share power source of each plant.
all plants in a network for all the plant to share power source of each plant.

● None● None(Mid to long term countermeasures)(Mid to long term countermeasures)● Regarding the power transmission from substation , switch from wires to● Regarding the power transmission from substation , switch from wires tounderground cable.
underground cable.
● Remote control: Secure power transmission route and cables for supplying power to● Remote control: Secure power transmission route and cables for supplying power tothe reactor from the power supply vehicle with remote control function. (Or is it
the reactor from the power supply vehicle with remote control function. (Or is it
possible to supply without wires?)possible to supply without wires?)● Improve earthquake resistance of substations and include it in the design● Improve earthquake resistance of substations and include it in the design
requirements.
requirements.
Secure emergency diesel generator (DG)
Secure emergency diesel generator (DG)
● Apply countermeasure to DG room's air inlet against flooding.
● Apply countermeasure to DG room's air inlet against flooding.
● Improve water tightness and pressure resistance of DG rooms.
● Improve water tightness and pressure resistance of DG rooms.
● Store control and power cables to allow power interchange between separate DG● Store control and power cables to allow power interchange between separate DG
rooms.
rooms.
(Mid to long term measures)(Mid to long term measures)● Place DG equipment on elevated areas (DG, power panel, etc.)● Place DG equipment on elevated areas (DG, power panel, etc.)● Improve DG power interchange function: interconnect all DG to allow sharing of● Improve DG power interchange function: interconnect all DG to allow sharing of
power to all nuclear reactors (Unit 5 & 6 were able to share power each other, but
power to all nuclear reactors (Unit 5 & 6 were able to share power each other, but
not designed so with Unit 1 to 4).
not designed so with Unit 1 to 4).
● Plant should be designed to function with minor flooding.
● Plant should be designed to function with minor flooding.
● The plant is vulnerable to an accident during regular inspection since DG is also
● The plant is vulnerable to an accident during regular inspection since DG is also
stopped for its own inspection. Install an additional DG to eliminate risk.
stopped for its own inspection. Install an additional DG to eliminate risk.
For air-cooling DG, place it in an elevated area together with the gas turbine. Air
For air-cooling DG, place it in an elevated area together with the gas turbine. Air
cooling type doesn’t require seawater pumps and seawater circulation system.
cooling type doesn’t require seawater pumps and seawater circulation system.
Set up fresh water cooling DG on an elevated area to avoid damage from tsunami.
Set up fresh water cooling DG on an elevated area to avoid damage from tsunami.

Secure emergency DG
Secure emergency DG(Mid to long term measures)(Mid to long term measures)● Automatically activate a DG if scrammed during earthquakes.
● Automatically activate a DG if scrammed during earthquakes.

149
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Secure power supply - 2
PurposeSecureSecurepower
power
SecureControl room
function
Secure highpressure
cooling system
Secure ventfunction
Secure lowpressure
cooling system
Secure ultimate
heat sink
Prevent hydrogen
explosion /radiation leak
Disaster
response manual/ infrastructure, etc.

Safety Measure (Prevention)

Safety Measure (Impact mitigation)

Secure emergency Diesel Generator (DG)
Secure emergency Diesel Generator (DG)
(Mid to long term measures)(Mid to long term measures)● Place diesel and gasoline tanks at an elevated area to avoid damage from● Place diesel and gasoline tanks at an elevated area to avoid damage fromtsunami.
tsunami.

Secure emergency DG
Secure emergency DG

Secure DC power
Secure DC power● Relocate equipment to indoors - into a pressure resistant and water tight● Relocate equipment to indoors - into a pressure resistant and water tightbuilding to avoid flooding by tsunami.
building to avoid flooding by tsunami.
● Station mobile battery vehicles (DC125V, 24V, and 250V) with cables in● Station mobile battery vehicles (DC125V, 24V, and 250V) with cables incase of loss of DC power supplies.
case of loss of DC power supplies.

Secure DC power
Secure DC power● None● None● None● None(Mid to long term measures)(Mid to long term measures)● Relocate DC power supplies to a higher place.
● Relocate DC power supplies to a higher place.
● Upgrade DC power supply capacity (from 8 hrs to 24 hrs or more).
● Upgrade DC power supply capacity (from 8 hrs to 24 hrs or more).
Secure AC power
Secure AC power● Improve water protection and pressure resistance of AC power supply● Improve water protection and pressure resistance of AC power supply
equipment.
equipment.
● Reinforce power supply vehicle:● Reinforce power supply vehicle:
・
Additional permanent units (secure necessary number of units based on・Additional permanent units (secure necessary number of units based on
the required load capacity). Review their location (i.e. elevated area)
the required load capacity). Review their location (i.e. elevated area)
・
Increase the type of vehicles: DC, AC, AC&DC, w/ generator, w/ DG etc.
・Increase the type of vehicles: DC, AC, AC&DC, w/ generator, w/ DG etc.
● Set multiple power-panel access points for power supply vehicles and● Set multiple power-panel access points for power supply vehicles andsecure water protection.
secure water protection.
● Increase the number of backup power supplies other than power supply● Increase the number of backup power supplies other than power supply
vehicles.
vehicles.
● For quick recovery of AC power, set up power supply cables and store● For quick recovery of AC power, set up power supply cables and store
tools for terminal handling in accessible areas for swift response.
tools for terminal handling in accessible areas for swift response.
(Mid to long term measures)(Mid to long term measures)● Sharing of AC power distribution （Cross-connect all units to allow● Sharing of AC power distribution （Cross-connect all units to allow
distribution of power through M/C and P/C）.
distribution of power through M/C and P/C）.
● Utilize air transport of power supply vehicle and backup power supply● Utilize air transport of power supply vehicle and backup power supply
after the tsunami and earthquake have subsided.（Set helipad on theafter the tsunami and earthquake have subsided.（Set helipad on theroof/vicinity of the reactor building.）
roof/vicinity of the reactor building.）● Transfer the AC power supply to a higher location.
● Transfer the AC power supply to a higher location.

Secure AC power
Secure AC power● None● None150
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Secure control room function
Purpose

Safety Measure (Prevention)

Secure power

Securing the functions of the control room
Securing the functions of the control room

Securing the functions of the control room
Securing the functions of the control room

● Secure livable condition for operators and monitoring function.
● Secure livable condition for operators and monitoring function.

● Secure livable condition for operators and monitoring function.
● Secure livable condition for operators and monitoring function.

SecureSecurecontrol room
control room
functionfunction・ Since the main control room has to function as a shelter during
・ Since the main control room has to function as a shelter during
emergencies, protection against radiation should be improved.
emergencies, protection against radiation should be improved.

Secure highpressure
cooling system(Mid to long term measures)(Mid to long term measures)

・ Store spare batteries in case meters and gauges stop working.
・ Store spare batteries in case meters and gauges stop working.
・ Store sufficient numbers of protective gear, masks, dosimeters,
・ Store sufficient numbers of protective gear, masks, dosimeters,
and other supplies. Since the situation in Fukushima Dai-ichi
and other supplies. Since the situation in Fukushima Dai-ichi
lasted a number of days, there should be at least a couple oflasted a number of days, there should be at least a couple ofdays worth of supplies stored.
days worth of supplies stored.

Secure ventfunction
Secure lowpressure
cooling system

・ To ensure vent and air conditioning system in the main control
・ To ensure vent and air conditioning system in the main control
room, emergency power systems such as gas turbines shouldroom, emergency power systems such as gas turbines should
be installed.
be installed.

Safety Measure (Impact mitigation)(Mid to long term measures)(Mid to long term measures)・ Due to power shut down the parameters, such as the reactor’s・ Due to power shut down the parameters, such as the reactor’swater level and pressure, were no longer observable. Portablewater level and pressure, were no longer observable. Portablemeasuring instruments and alternative measurements should bemeasuring instruments and alternative measurements should be
developed .
developed .

Secure ultimate
heat sink
Prevent hydrogen
explosion /radiation leak
Disaster
response manual/ infrastructure, etc.

151
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Secure high pressure cooling system
PurposeSecure power

Securecontrol room
function
Secure highSecure highpressurepressure
cooling system
cooling system
Secure ventfunction
Secure lowpressure
cooling system
Secure ultimate
heat sink

Safety Measure (Prevention)

Safety Measure (Impact mitigation)

Securing high pressure coolant
Securing high pressure coolant

Securing high pressure cooling system
Securing high pressure cooling system● The HPCI and RCIC are installed at the basement of the● The HPCI and RCIC are installed at the basement of thereactor building. Although the reason it stopped working wasreactor building. Although the reason it stopped working wasdue to problems with the power, it’s still necessary to
due to problems with the power, it’s still necessary tomaintain water seals and pressure resistance of the room tomaintain water seals and pressure resistance of the room toensure the safety of the pumps and motors inside.
ensure the safety of the pumps and motors inside.

● Work progress at night was slow. There was a delay in● Work progress at night was slow. There was a delay inrestoring the high pressure cooling system which worsened therestoring the high pressure cooling system which worsened thesituation in the plant, and delayed the staging of the lowsituation in the plant, and delayed the staging of the lowpressure cooling system. To improve efficiency of the fieldpressure cooling system. To improve efficiency of the field
work, mark valves and machines with fluorescent paint for
work, mark valves and machines with fluorescent paint foreasy detection. Coating the temporary power cables witheasy detection. Coating the temporary power cables withfluorescent paint will provide easy direction to their installed
fluorescent paint will provide easy direction to their installed
locations.
locations.

● Since the high-pressure water injection can be done by SLC,
● Since the high-pressure water injection can be done by SLC,
CRD, and CUW systems, it’s important to secure power
CRD, and CUW systems, it’s important to secure power
supplies for these systems. It is necessary to consider storing
supplies for these systems. It is necessary to consider storing
temporary power supplies to ensure power for the systems.
temporary power supplies to ensure power for the systems.

(Mid to long term measures)(Mid to long term measures)● It would take too much time and cause delays in decision● It would take too much time and cause delays in decision
making if unable to access the site to confirm the state of the
making if unable to access the site to confirm the state of thehigh pressure cooling system. It will be effective to havehigh pressure cooling system. It will be effective to havemultiple means to observe the site. This will require power but
multiple means to observe the site. This will require power but
we suggest installing ITV (for vision), sound monitors, andwe suggest installing ITV (for vision), sound monitors, andvibration sensors to allow remote monitoring the status of thevibration sensors to allow remote monitoring the status of thepumps, gauges and valves.
pumps, gauges and valves.

Prevent hydrogen
explosion /radiation leak
Disaster
response manual/ infrastructure, etc.

152
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Secure vent function
PurposeSecure power

Safety Measure (Prevention)
Secure containment vessel vent function
Secure containment vessel vent function

Secure containment vessel vent function
Secure containment vessel vent function● None● None● Prepare items for setting up vent line (temporary power● Prepare items for setting up vent line (temporary power
supply, air tank) beforehand for efficiency.
supply, air tank) beforehand for efficiency.
● Because vent operation failed in containment vessel of Unit
● Because vent operation failed in containment vessel of Unit2, reconsider the operation guideline on the pressure level in
2, reconsider the operation guideline on the pressure level in
PCV to conduct ventilation (as well as the pressure
PCV to conduct ventilation (as well as the pressure
configuration of the rupture disk).
configuration of the rupture disk).

Securecontrol room
function
Secure highpressure
cooling system(Mid to long term measures)(Mid to long term measures)● Install a neutron monitor inside the PCV to observe the● Install a neutron monitor inside the PCV to observe theactivities inside the core during meltdown.
activities inside the core during meltdown.
● Multiplex the air pressure supply and vent line and classify● Multiplex the air pressure supply and vent line and classify
them to the 'safety-system' class to ensure the reliability.
them to the 'safety-system' class to ensure the reliability.
● Too much time was consumed in setting up the vent line.
● Too much time was consumed in setting up the vent line.
Place the valve at an accessible area and allow manual
Place the valve at an accessible area and allow manual
operation.
operation.
● Given that ventilation with the rupture disk in reactor No.2
● Given that ventilation with the rupture disk in reactor No.2
was unsuccessful, consider the use of a valve for ventilation
was unsuccessful, consider the use of a valve for ventilation
without the disk.
without the disk.

Secure vent
Secure ventfunctionfunction
Secure lowpressure
cooling system
Secure ultimate
heat sink
Prevent hydrogen
explosion /radiation leak
Disaster
response manual/ infrastructure, etc.

Safety Measure (Impact mitigation)

Depressurization with SR valve operation
Depressurization with SR valve operation

Depressurization with SR valve operation
Depressurization with SR valve operation● None● None● Unable to perform depressurization with SR valve due to DC● Unable to perform depressurization with SR valve due to DC
power outage. Prepare batteries in the central control room.
power outage. Prepare batteries in the central control room.
(Mid to long term measures)(Mid to long term measures)● Consider SR valve mechanism that doesn't rely solely on DC● Consider SR valve mechanism that doesn't rely solely on DC
power.
power.
● Consider multiple methods for core depressurization.
● Consider multiple methods for core depressurization.

153
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Secure Low pressure cooling system
PurposeSecure power

Securecontrol room
function

Safety Measure (Prevention)
Secure Low Pressure Cooling System
Secure Low Pressure Cooling System

Secure Low Pressure Cooling System
Secure Low Pressure Cooling System● Place emergency core cooling pumps, used for low pressure● Place emergency core cooling pumps, used for low pressurestate, at a higher location to avoid damage from tsunami, orstate, at a higher location to avoid damage from tsunami, or
secure water protection and pressure resistance.
secure water protection and pressure resistance.

● Reinforce water supply paths: Confirm other means of water● Reinforce water supply paths: Confirm other means of watersupply than fire truck (i.e. air-lift, sea transport).
supply than fire truck (i.e. air-lift, sea transport).

Secure highpressure
cooling system● Secure appropriate number of fire trucks and hoses, and station● Secure appropriate number of fire trucks and hoses, and station
the units on high ground. Take into account the water source,
the units on high ground. Take into account the water source,water injection range, and water injection capacity whenwater injection range, and water injection capacity whenselecting the fire trucks.
selecting the fire trucks.

Secure ventfunction● Set multiple water injection points for fire trucks.
● Set multiple water injection points for fire trucks.

Secure low
Secure lowpressurepressure
cooling system
cooling system
Secure ultimate
heat sink
Prevent hydrogen
explosion /radiation leak
Disaster
response manual/ infrastructure, etc.

Safety Measure (Impact mitigation)● Investigate and determine the cause of trouble with the diesel● Investigate and determine the cause of trouble with the dieseldriven fire pump. Add the countermeasures to the AM.
driven fire pump. Add the countermeasures to the AM.

● As there was no means of monitoring the spent fuel pool in the● As there was no means of monitoring the spent fuel pool in thefield, monitoring instruments for temperature and water level
field, monitoring instruments for temperature and water level(requires power) need to be installed. As a backup in case(requires power) need to be installed. As a backup in caseinstruments do not work, prepare portable contactless
instruments do not work, prepare portable contactless
thermometer and water level indicator.
thermometer and water level indicator.
● Secure reliability by multiplexing cooling system for spent fuel● Secure reliability by multiplexing cooling system for spent fuel
pool.
pool.

(Mid to long term measures)(Mid to long term measures)(Long term measures)(Long term measures)● Reinforce water source: Supply water from multiple sources● Reinforce water source: Supply water from multiple sources
such as water tank, dam, reservoir, lake, river, sea. Review
such as water tank, dam, reservoir, lake, river, sea. Review
whether the methods and capacity are sufficient. If the water
whether the methods and capacity are sufficient. If the water
will be used as a coolant, consider the following:
will be used as a coolant, consider the following:● Secure water source for low-pressure injection which can be● Secure water source for low-pressure injection which can beused for fire fighting.
used for fire fighting.

・
Whether boric acid can be added.
・
Whether boric acid can be added.
・
Develop circulation system that allows contaminated water in・
Develop circulation system that allows contaminated water inthe reactor building to be used as coolant.
the reactor building to be used as coolant.
・Prepare multiple routes for the coolant.
・Prepare multiple routes for the coolant.

154
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Secure ultimate heat sinkPurposeSecure power

Securecontrol room
function
Secure highpressure
cooling system

Safety Measure (Prevention)

Safety Measure (Impact mitigation)

Secure seawater system
Secure seawater system

Secure seawater cooling functions
Secure seawater cooling functions● Need to prepare portable water pump and temporary power● Need to prepare portable water pump and temporary power
supply in case the seawater pumps malfunction due to tsunami.
supply in case the seawater pumps malfunction due to tsunami.

● Store cleaning equipment for motor winding and spare parts.
● Store cleaning equipment for motor winding and spare parts.

● The seawater pump in the building was flooded and● The seawater pump in the building was flooded andmalfunctioned. Aside from improving the water seal andmalfunctioned. Aside from improving the water seal andpressure resistance of the building, it is also important topressure resistance of the building, it is also important tocompletely shut the building doors when there is a tsunami
completely shut the building doors when there is a tsunami
warning.
warning.

Secure ventfunction(Mid to long term measures)(Mid to long term measures)(Mid to long term measures)(Mid to long term measures)

Secure lowpressure
cooling system● When adding or replacing emergency generators, secure the● When adding or replacing emergency generators, secure thecooling line for the air-cooled type as a backup system (notcooling line for the air-cooled type as a backup system (notrelying on seawater coolant).
relying on seawater coolant).

● Since the motors for seawater pump malfunctioned due to the● Since the motors for seawater pump malfunctioned due to thetsunami, consider sealed motors (to reinforce pressure
tsunami, consider sealed motors (to reinforce pressure
resistance and water protection).
resistance and water protection).

Secure ultimate
Secure ultimate
heat sinkheat sink
Prevent hydrogen
explosion /radiation leak

● Operate feed-and-bleed cooling with the wet well vent (secure● Operate feed-and-bleed cooling with the wet well vent (secureheat sink until cold shutdown.).
heat sink until cold shutdown.).
● Build sea-wall or breakwater.
● Build sea-wall or breakwater.
● Implement an alternative core cooling system (water source,● Implement an alternative core cooling system (water source,
power source, and water injection system).
power source, and water injection system).

Disaster
response manual/ infrastructure, etc.

155
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Prevent hydrogen explosion/radiation leakPurposeSecure power

Securecontrol room
function
Secure highpressure
cooling system
Secure ventfunction
Secure lowpressure
cooling system
Secure ultimate
heat sink
Prevent hydrogen
Prevent hydrogen
explosion /explosion /radiation leakradiation leak
Disaster
response manual/ infrastructure, etc.

Safety Measure (Prevention)

Safety Measure (Impact mitigation)

Prevent hydrogen explosion
Prevent hydrogen explosion

Prevent hydrogen explosion
Prevent hydrogen explosion● Install hydrogen ventilation in the nuclear reactor building● Install hydrogen ventilation in the nuclear reactor building
before it’s filled with hydrogen (vent system with remote
before it’s filled with hydrogen (vent system with remotecontrol + manual control + radioactive material filtering).
control + manual control + radioactive material filtering).

● To prevent rupture disk from not opening, conduct regular● To prevent rupture disk from not opening, conduct regularinspections and replacement.
inspections and replacement.

● Reinforce air tightness of PCV: Review the materials in the● Reinforce air tightness of PCV: Review the materials in theseals including the DW flange, electrical routing, hatches etc.
seals including the DW flange, electrical routing, hatches etc.
Reinforce resistance against high temperatures and pressure.
Reinforce resistance against high temperatures and pressure.
● In case mass hydrogen is generated, prevent it from● In case mass hydrogen is generated, prevent it fromaccumulating in a closed space.
accumulating in a closed space.
・ Install hydrogen detectors in closed spaces. (Transmit signal
・ Install hydrogen detectors in closed spaces. (Transmit signal
with own battery or RF) .
with own battery or RF) .
・ Perform preventive measures such as injecting nitrogen
・ Perform preventive measures such as injecting nitrogen
inside of the PCV when venting.
inside of the PCV when venting.

● In Fukushima Dai-ichi, although they were apprehensive of● In Fukushima Dai-ichi, although they were apprehensive ofleak of radioactive materials in Unit 1, they did not anticipate
leak of radioactive materials in Unit 1, they did not anticipate
a hydrogen explosion. Define how to handle hydrogena hydrogen explosion. Define how to handle hydrogen
explosions in the AM manual and conduct training to ensure
explosions in the AM manual and conduct training to ensure
accurate response.
accurate response.

(Mid to long term measures)(Mid to long term measures)● Reconsider the shape of the upper area/ ceiling of the nuclear● Reconsider the shape of the upper area/ ceiling of the nuclear
reactor, PCV, and reactor building so that the hydrogen does
reactor, PCV, and reactor building so that the hydrogen does
not accumulate in one narrow space (i.e. slant ceiling to
not accumulate in one narrow space (i.e. slant ceiling toredirect the gas).
redirect the gas).
● Consider reinforcing the concrete or install debris catcher to● Consider reinforcing the concrete or install debris catcher toprevent debris from penetrating PCV (prevent debrisprevent debris from penetrating PCV (prevent debrisconcrete reaction in pedestal).
concrete reaction in pedestal).
Radiation leak prevention
Radiation leak prevention(Mid to long term measures)(Mid to long term measures)● Considering that hydrogen explosion spread radioactive● Considering that hydrogen explosion spread radioactive
materials, evaluate the effectiveness of the wet well vent andmaterials, evaluate the effectiveness of the wet well vent andconsider installing vent filter.
consider installing vent filter.

156
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSafety Measures...

Extremely Confidential

Safety Measure: Disaster response manual / infrastructure etc.
PurposeSecure power

SecureControl room
function
Secure highpressure
cooling system
Secure ventfunction
Secure lowpressure
cooling system
Secure ultimate
heat sink
Prevent hydrogen
explosion /radiation leak
DisasterDisaster
responsemanualresponsemanual/ infrastructure,etc.
/ infrastructure, etc.

Management response

Management response

Update disaster response manual (AM)Update disaster response manual (AM)

Reinforce infrastructure
Reinforce infrastructure● Redesign AM: How many hours should the plant’s water and● Redesign AM: How many hours should the plant’s water andpower sources last? How to bring in alternative resources from off
power sources last? How to bring in alternative resources from offsites? Implement the following:sites? Implement the following:● Enforce assembly of operators to the power plant after an● Enforce assembly of operators to the power plant after anearthquake (including during the night and on holidays). Secure
earthquake (including during the night and on holidays). Securenecessary staff for the Emergency Response Room as well (requirenecessary staff for the Emergency Response Room as well (requireassembly within X hours).
assembly within X hours).

・

・

・

・

・

・

Define the numerical requirements specifically as to the minimum
Define the numerical requirements specifically as to the minimum
number of hours for which coolant and power should last on-site,
number of hours for which coolant and power should last on-site,
and add to the operation manual.
and add to the operation manual.
In the logistics and accident manuals, specify how to bring inIn the logistics and accident manuals, specify how to bring in
additional power, coolant, and other supplies from off-site before
additional power, coolant, and other supplies from off-site before
the on-site power and coolant are lost.
the on-site power and coolant are lost.
Reinforcement of training: Do not let the training end with the
Reinforcement of training: Do not let the training end with the
preparation phase. It's necessary to cover the actual processes (e.g.
preparation phase. It's necessary to cover the actual processes (e.g.
actual connection of cable terminal) and reflect its mechanism inactual connection of cable terminal) and reflect its mechanism in
the training as well.
the training as well.

● Revise the manual of power restoration: The manual originally● Revise the manual of power restoration: The manual originallygives guidelines for restoring short term power loss. Revise thegives guidelines for restoring short term power loss. Revise themanual to anticipate up to a few days of power loss.
manual to anticipate up to a few days of power loss.
● Since earthquake and tsunami can hit all the reactors in the plant at● Since earthquake and tsunami can hit all the reactors in the plant at
the same time, there should be plant-wide training with night andthe same time, there should be plant-wide training with night andholiday scenarios as well.
holiday scenarios as well.
Review assessment method and organization of the
Review assessment method and organization of theearthquake and tsunami risk (Mid to long term measures)
earthquake and tsunami risk (Mid to long term measures)● Revise the organization of the nuclear disaster response to handle● Revise the organization of the nuclear disaster response to handle
concurrent accidents at multiple plants.
concurrent accidents at multiple plants.
● Include risk assessment in regards to the ‘power’ of tsunami● Include risk assessment in regards to the ‘power’ of tsunami
besides its height.
besides its height.
● Assess the risk of tsunami and earthquake more frequently on● Assess the risk of tsunami and earthquake more frequently on
regular basis
regular basis● Communication means among operators in a control room of each
● Communication means among operators in a control room of eachplant, accident response members in the field, on-site emergency
plant, accident response members in the field, on-site emergency
response headquarter, and the central control room were cut off,
response headquarter, and the central control room were cut off,
thus affecting timely reports. This slows down the emergency
thus affecting timely reports. This slows down the emergency
response, so it's important to secure and distribute appropriate
response, so it's important to secure and distribute appropriate
numbers of communication equipments (means of communication).
numbers of communication equipments (means of communication).
● Improve the environment of the Emergency Response Room by● Improve the environment of the Emergency Response Room byproviding sleeping quarters and bedding.
providing sleeping quarters and bedding.
● Improve the Anti-seismic Isolation Tower’s resistance against● Improve the Anti-seismic Isolation Tower’s resistance against
tsunami (secure emergency power supply).
tsunami (secure emergency power supply).
● To improve the accessibility of the plant after earthquake and● To improve the accessibility of the plant after earthquake andtsunami:tsunami:・ Secure required numbers of heavy machineries and operators
・ Secure required numbers of heavy machineries and operatorsfor clearing debris.
for clearing debris.
・ Bolt-down the gasoline tanks to avoid floating.
・ Bolt-down the gasoline tanks to avoid floating.
(Mid to long term measures)(Mid to long term measures)
・ Reinforce roads to the headquarters (including anti-liquefaction)
・ Reinforce roads to the headquarters (including anti-liquefaction)
・ Ensure that the transport path remains after earthquakes and・ Ensure that the transport path remains after earthquakes andtsunami (Construct a path that won't crack or suffer liquefaction.
tsunami (Construct a path that won't crack or suffer liquefaction.
No manholes).
No manholes).
● Reinforce roads and bridges leading to the power plant.
● Reinforce roads and bridges leading to the power plant.
● Secure safety of the workers: Consider responding remotely and● Secure safety of the workers: Consider responding remotely andwith fewer staff. (e.g. Set up long distance hoses beforehand, allow
with fewer staff. (e.g. Set up long distance hoses beforehand, allow
remote control of hoses as with a crane, etc.)
remote control of hoses as with a crane, etc.)
157
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Comparison
Comparisonwith
withNISANISAinstructions
instructions(Current(Currentstressstresstest)
test)
・・Point
Pointofofview
view・・TechnicalTechnicalmeasures
measures

158
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Comparison with ongoing test

Safety Measure: Secure power (external AC power and emergency DG)
Category Countermeasure

Match withNISA ST?

Match with
report to IAEA?

Improve water protection and pressure resistance of switching stations.

○○Switching stations should be located at elevated areas, or sea-walls should be built toprotect the equipment from tsunami.

○○

Evaluate and improve earthquake resistance of switching stations, transmission line
towers and power plants. Furthermore, include earthquake resistance in the design
requirements.

○○

Minimize frequency of external power outage by drawing multiple power lines fromthe substation (minimum of two separate lines). Or connect external power of allplants in a network.

○○

Content

Secure external Regarding the substation power transmission, switch from overhead wires to
AC power
underground cable.

Securepower

××

Remote control: Secure power transmission route and cables for remote supply of
power to the nuclear reactor from the power supply vehicle with remote control. (or isit possible to supply without wires?)××

Improve earthquake resistance of substations and include it in the official design
requirements.

○○

Protect air inlet of DG room from flooding.

○○

Improve water protection and pressure resistance of DG rooms.

○

○

○

○

○

○

○

○

○

○

○

○

○

○

×

×

Store control and power cables to allow power interchange between separate DG
rooms.
Place DG equipment at higher elevation (DG, power panel, etc.)
Improve sharing of DG power: Interconnect all DG to enable all the reactors to sharepower supply from others. (Unit 5&6 could share power supplies each other but notdesigned so with Units 1 to 4).

Secureemergency
diesel generator Plant should be designed to function with minor flooding.
(DG)
The plant becomes vulnerable against an accident during regular inspection since the

DG is stopped for their own inspection. Install an additional DG. For air-cooling DG,
place it in an elevated area together with the gas turbine. Air cooling DG doesn’t
require seawater pumps and seawater circulation system. For fresh-water cooling
DG, set it up on an elevated area to avoid damage from tsunami.
Place diesel and gasoline tanks on an elevated area to avoid damage from tsunami.

Automatically activate DG if the reactor scrammed

Notes

reinforce powertransmission line
(instruction docs)
Needs another form
(IAEA、industry）

159

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Secure power (DC and AC power)
Item

Counter
measureMatch withNISA ST?

Match with reportto IAEA?

○○

Station mobile battery vehicles (DC125V, 24V, and 250V) with cables in case of
accident to DC power supplies.

○○

Relocate DC power supplies to a higher elevation.

○○

Upgrade the capacity of DC power supply (from 8 hrs to 24 hrs or more).

○

○

○

○

○

○

Set multiple access points of power panel for power supply vehicles and securewater seal.

○○

Increase the number of backup power sources other than power supply vehicles.

○○

To quickly recover AC power, set up power supply cables and store tools forterminal handling in accessible areas.

○○

AC power distribution（To enable all Units to share power sources through the
M/C and P/C）○○

Transport power supply vehicle and backup power source by air after the tsunami
and earthquake have subsided.（Set helipad on the roof/vicinity of the reactor
building.）

××

Transfer the AC power supply to a higher location.

○○

Content
Relocate equipment indoors - into a pressure resistant and water tight building to
avoid flooding by tsunami. Relocate DC power supplies to a higher location.

Secure DC
power

Notes

Improve water tightness and pressure resistance of AC power equipments.

Power supply vehicle reinforcement
・Store additional units on site (secure necessary number of units based on therequired load capacity). Review location (i.e. elevated area)
・Increase the type of power supply vehicles: DC, AC, AC & DC, w/ generator,
w/DG, etc.
Secure power

Secure AC
power

160
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Secure control room function and high pressure cooling system
Item

Counter
measureContent
Improve radiation protection of the main control room to avoid radiation during
emergencies.
Store spare batteries in case meters and gauges stop working.

Secure livable Store sufficient numbers of protective gear, masks, dosimeters, and other
Securecondition for supplies. Since the situation in Fukushima Dai-ichi lasted a few days, there should
function of operators and be at least a couple of days worth of supplies.
control roommonitoring To ensure vent and air conditioning system in the main control room, emergency
funciton
power such as gas turbines should be installed.
Due to power shut down the parameters, such as the water and pressure level ofthe core, were no longer observable. Portable measuring instruments andalternative measurements should be developed .
The HPCI and RCIC are installed in the basement of the reactor building.
Although the reason they stopped working was due to the loss of power, it’s stillnecessary to maintain water protection and pressure resistance of the room tosecure the pumps and motors inside it.
Since the systems for SLC, CRD, and CUW can be used for high pressure
cooling, it’s important to secure power supplies for these systems including
temprary power supply.
Work at night was slow. There was a delay in restoring high pressure cooling
Secure high Secure highsystem which worsened the situation in the plant, and delayed the staging of lowpressurepressurepressure cooling system. To improve efficiency in the field work, mark valves andcooling system cooling system
machines with fluorescent paint for easy detection. Coating the temporary power
cables with fluorescent paint will provide easy direction to its location.
It would take too much time and cause delay in the decision making if unable toaccess the site to confirm the state of the high pressure cooling. It will beeffective to have multiple means to observe the site. Install ITV (for vision),sound monitor, and vibration sensors to allow remote monitoring of the pumps,
gauges, and valve.

Match withNISA ST?

Match with
report to IAEA?

○

○

○

○

○

○

○

○

○

○

○

○

○

○

Notes

No policy to check
operation state××

No measures for working
night time
×

×

161
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Secure Low pressure cooling system
Item

Counter
measureMatch withNISA ST?

Match with reportto IAEA?

○○

Secure appropriate number of fire trucks and hoses, and station them on highground. Consider the source, range, and capacity of water injection whenselecting fire trucks.

○○

Set multiple water injection points for fire trucks○○

Investigate and determine the cause of trouble with the diesel-driven fire pump.
Reflect in the countermeasures.

××

Reinforce water supply paths: Confirm other delivery means of water than fire
truck (i.e. air-lift, sea transport).

○○

Content
Place pumps for low-pressure emergency core cooling on a high location to avoid
damage from tsunami. Secure water protection and pressure resistance.

Secure Low
Pressure
Cooling
SystemSecure Low
Pressure
Cooling
SystemReinforce water source: Supply water from multiple sources such as water tank,dam, reservoir, lake, river, sea. Review whether the supply methods and capacity
are sufficient. If the water is used as core coolant, consider the following:・
Whether boric acid can be added.
・The circulation system which use contaminated waterin the reactor building as coolant.
・Prepare multiple routes for the coolant.
Secure water for low-pressure injection for fire fighting in addition to core
coolant.

There was no means of monitoring the spent fuel pool in the field, so monitoring
instruments for temperature and water level (requires power) are necessary. As
Secure spent alternatives in case instruments are not working, prepare portable contactless
fuel pool
thermometer and water level indicator.
systemSecure reliability by multiplexing cooling system for spent fuel pool.

Notes

No reference on recylingof contaminated water.
Mentioned air coolingmethod
○
×
×

○
×
×

×

×

×

○

×

×

Mentioned securing ofwater source for coolingsystem (ST instructions,
IAEA)
Stated to secure cooling
functions for spent fuelpool (ST instructions).
Mentioned securingcooling function

162
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Secure ventilation function
Item

Counter
measureContent
Prepare items for setting up vent line (temporary power supply, air tank)beforehand for efficiency.
Given that PCV vent operation failed in Unit 2, reconsider the activation pressureof ventilation (= the configuration of the rupture disk to open).

Install a neutron monitor inside the PCV to observe the activities inside the core
Secureduring meltdown.
containment
vessel vent Multiplex and improve the equipments for vent line to stabilize air supply for thefunction
operation. Designate them as the 'safety system'.

Secure ventfunction

Match withNISA ST?

Match with
report to IAEA?

○

○

×

×

×

○

○

○

Consumed too much time in setting up the vent line. Place the valve at anaccessible area and redesign for manual operation.

○○

Gievn that venting with rupture disk in Unit 2 was unsuccessful, consider to use avalve for vent operation.

××

Unable to perform depressurization by the SR valve due to DC power outage.

○

○

×

×

×

×

Depressurization with
SR valve Consider SR valve that can work by other than DC power.
operation
Consider multiple methods on nuclear reactor depressurization.

Notes

Mentioned improving ventstream operation (IAEA)

Mentioned indicators formonitoring core status(industry report)

163
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Secure low pressure cooling system and ultimate heat sink

Counter
measureMatch withNISA ST?

Match with reportto IAEA?

○

○

○

○

○

○

When adding or replacing emergency DG, secure cooling line for air-cooling typeas backup (not relying on seawater coolant).

○○

Operate feed-and-bleed cooling with wet well vent (secure heat sink until cold
shutdown.).

×

×

○

×

×

×

○

○

Item

Content
Need to prepare portable water pump and temporary power supply in case theseawater pumps malfunction from tsunami.
The seawater pump in the building was flooded and malfunctioned. Aside from
improving the water seal and pressure resistance of the building, it is also
important to completely shut the building doors when there is a tsunami warning.

Notes

Store cleaning equipments for motor winding and secure spare parts.

Secureultimate headsink

SecureseawatersystemBuild sea-wall or breakwater
Have an alternative core cooling system (water source, power source and water
injection system)
Consider completely sealed motors (pressure resistance, water protection
reinforced) as the seawater pump motors malfunctioned from the tsunami.

164
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Prevent hydrogen explosion/radiation leak

Item

Counter
measureMatch with NISA
Match withST?
report to IAEA?

Content
Install ventilation for hydrogen in the reactor building to prevent accumulation(with remote control + manual control + radioactive material filtering).

○

Reinforce air tightness of PCV: Review the materials in the seals such as D/Wflange, electric cabling routes, hatches, etc. Reinforce resistance against hightemperature and pressure.

Preventhydrogen
explosion/
Radiation leak

Preventhydrogen
explosion

To prevent rupture disk from failing to open, conduct regular inspection andreplacement.
In Unit 1 of 1F, though they were apprehensive of radiation leak, they did't
anticipate a hydrogen explosion. Define AM as to how to handle hydrogen
explosions and conduct training to ensure accurate procedure.
In case mass hydrogen accumulated, prevent its accumulation in a closed space.
・Install hydrogen detectors in closed spaces (Transmit signal using own battery orRF)・Perform preventive measures such as nitrogen seal inside the PCV whenventing.
Consider reinforcing the concrete or install debris catcher to prevent debris
penetrating the PCV (prevent debris-concrete reaction in pedestal).

With the hydrogen explosion causing spread of radioactive materials, evaluate thePrevent
effectiveness of the wet well vent and consider installing vent filter.
radiation leak

Notes

○

×

×

×

×

○

○

×
×

○
×

×

○

×

×

×

○

No mention of PCV
reinforcement

Mentioned prevention ofhydrogen accumulation (STinstructions)Mentioned vent systemreinforcement (IAEA)

165
Note: 1F = Fukushima Dai-ichi Nuclear Power plant

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Disaster response manual / Reinforcement of infrastructure

Item

CountemeasureContent

Match withNISA ST?

Match with reportto IAEA?

○

○

○

○

○

○

○

○

○

○

Notes

Redesign AM: How many hours should the plant’s water and power sources last? How
to bring in alternative resources from off sites? Implement the following:

Disaster
responsemanual /reinforcement of
infrastructure

・Define the numerical requirements specifically as to the minimum number ofhours for which coolant and power should last on-site, and add tothe operation manual.
・ In the logistics and accident manuals, specify how to bring in additional
power, coolant, and other supplies from off-site before the on-site powerand coolant are lost.
Update・Reinforcementof training: Do not let the training end with the preparation
disasterphase. It's necessary to cover the actual processes (e.g. actual connection
responsemanual (AM) of cable terminal) and reflect its mechanism in the training as well.
Revise the manual of power restoration: The manual originally gives guidelines forrestoring short term power loss. Revise the manual to anticipate up to a few days ofpower loss.
Since earthquake and tsunami can hit all the reactors in the plant at the same time, there
should be plant-wide training with night and holiday scenarios as well.

166
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedComparison with ongoing test

Extremely Confidential

Safety Measure: Disaster response manual / Reinforcement of infrastructure
Item

Disaster
responsemanual /reinforcement of infrastructure

Counter
measureReinforce
infrastructure

M atch withNISA ST?

Content

M atch with
report to
IAEA?

Note
M entioned to work out
as necessary
countermeasure.

Enforce assembly of operators to the power plant after an earthquake (including during the night
and on holidays). Secure necessary staff for the Emergency Response Room as well (requireassembly within X hours).

×○

Communication means among operators in a control room of each plant, accident response
members in the field, on-site emergency response headquarter, and the central control room were
cut off, thus affecting timely reports. This slows down the emergency response, so it's importantto secure and distribute appropriate numbers of communication equipments (means ofcommunication).

○○

Improve the environment of the Emergency Response Room by providing sleeping quarters andbedding.

××

Improve the Anti-seismic Isolation Tower’s resistance against tsunami (secure emergency power
supply).

×

×

○

○

Reinforce roads and bridges leading to the power plant.

××

Secure safety of the workers: Consider responding remotely and with fewer staff. (e.g. Set up
long distance hoses beforehand, allow remote control of hoses as with a crane, etc.)

××

M entioned rescue team,materials and equipment
for emergency response×○

M entioned issues on
locations with multiple
reactors (IAEA)

×

×

×

×

To improve the accessibility of the plant after earthquake and tsunami:・ Secure required numbers of heavy machineries and operators for clearing debris.
・ Bolt-down the gasoline tanks to avoid floating.
・ Reinforce roads to the headquarters (including anti-liquefaction)
・ Ensure that the transport path remains after earthquakes and tsunami(Construct a path that won't crack or suffer liquefaction. No manholes).

Review the Revise the organization of the nuclear disaster response to handle concurrent accidents at multiple
earthquake and plants.
tsunamiassessment
Include risk assessment in regards to the ‘power’ of tsunami besides its height.
method andorganization

Assess the risk of tsunami and earthquake more frequently on regular basis

167

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Accident
Accident Management
Management (AM)(AM)
・・WhatWhatcancanbebelearned
learnedfrom
fromthetheaccident
accidentanalysis?
analysis?
・・WhatWhatdecision-making
decision-makingmechanism
mechanismshould
shouldbe
beestablished?
established?

168
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM system...Organizing the issues...

Extremely Confidential

Issues – Many lessons and issues regarding system and decision making process of
the Accident Management (AM)
Suspected cause

Event / Issue

Safety Measures / Lessons●

Constant education andtraining on accident
response procedures.

● Field personnel under Site Superintendent and Shift Supervisors acted with emphasis● Field personnel under Site Superintendent and Shift Supervisors acted with emphasison safety in consistency with the AM manual. Plant operators have undergone
on safety in consistency with the AM manual. Plant operators have undergone
practical operation training in addition to the AM training. We believe that the training
practical operation training in addition to the AM training. We believe that the training
was effective in the response process in the site but only until the hydrogen explosion.
was effective in the response process in the site but only until the hydrogen explosion.

● Reaffirmed importance and reinforced
routine training● Emphasis on execution speed of safetymeasures●

Insufficient procedures andfunctions for information
sharing and means ofcommunication
Establish joint headquarters
for emergency response● Initially the issue of insufficient communication between TEPCO head office and● Initially the issue of insufficient communication between TEPCO head office andpower plants, and communication between TEPCO and the national government was
power plants, and communication between TEPCO and the national government was
picked up by the press (e.g. government directly contacting Fukushima Dai-ichi). This
picked up by the press (e.g. government directly contacting Fukushima Dai-ichi). This
was left un-clarified.
was left un-clarified.
● This problem seemed to have resolved with the establishment of joint headquarters for● This problem seemed to have resolved with the establishment of joint headquarters for
emergency response between the national government and TEPCO on 3/15.
emergency response between the national government and TEPCO on 3/15.

● Improve quality, capacity, and speed of
information shared● Create a system to achieve the above● Reaffirmed importance of a system forreal-time information sharing.

●

Insufficient measures forhandling multiple plants
concurrently resulted indelay of response● The head office at TEPCO had to respond to a total of 10 plants in Dai-ichi and Dai-ni.
● The head office at TEPCO had to respond to a total of 10 plants in Dai-ichi and Dai-ni.
However, they did not anticipate concurrent accidents occurring in multiple plants.
However, they did not anticipate concurrent accidents occurring in multiple plants.
Although they had a sufficient number of employees (head office 200, Dai-ichi 400,
Although they had a sufficient number of employees (head office 200, Dai-ichi 400,
Dai-ni 200-300) they did not have sufficient organization, response staff, and training
Dai-ni 200-300) they did not have sufficient organization, response staff, and training
to be effective in the response.
to be effective in the response.

● Assign and train personnel to respondto multiple severe accidents for each
plant

●

Insufficient preparation andtraining for supplies
arrangement
Swift supply delivery by the
Defense Force● Transporting equipment from head office to the plants wasn’t executed smoothly (e.g.
● Transporting equipment from head office to the plants wasn’t executed smoothly (e.g.
sending from JV and Obama CC). They also were having difficulties with the required
sending from JV and Obama CC). They also were having difficulties with the required
supplies (and timing) for the severe accident like this.
supplies (and timing) for the severe accident like this.
● Since the establishment of joint headquarters of the Government and TEPCO on 3/15,● Since the establishment of joint headquarters of the Government and TEPCO on 3/15,
the Self Defense Force was able to transport supplies smoothly.
the Self Defense Force was able to transport supplies smoothly.

● Design a structure and training forordering equipment. Include means ofcommunication, specification list, anddelivery check for outgoing andincoming equipment.
● Establish manual and structure forcollaboration with Self Defense Forceduring severe accidents.

Power outage andcommunication problem in
offsite center● During the day of the earthquake, the offsite center wasn’t functioning due to power● During the day of the earthquake, the offsite center wasn’t functioning due to power
failure. Later they were also unable to use the TV conference system (another one at
failure. Later they were also unable to use the TV conference system (another one at
TEPCO booth was working). For this reason they had difficulties sharing information
TEPCO booth was working). For this reason they had difficulties sharing information
at most crucial
at most crucial● Secure emergency power supply andmeans of communication in offsite
centers

●

●

●

169
Unauthorized copying or distribution of this file is prohibited.
Copyright Team H2O Project all rights reserved

Extremely Confidential

AM system...Organizing the issues...

(continued)
Suspected cause

Event / Issue

Safety Measures / Lessons● Purpose of offsite center
was unclear. Lack ofcommon understanding of
its purpose among
stakeholders. Insufficienttraining.

●●

The
Theoffsite
offsitecenter
centerserved
servedits
itspurpose
purposeasasan
aninformation
informationsharing
sharingcenter
centerafter
afterthetherestoration,but
itdidn’tseem
tohave
served
as
a
place
for
conferencesandrestoration, but it didn’t seem to have served as a place for conferences anddecision-making.
decision-making.The
Thescalescaleofofthe
theevacuation
evacuationgrew
grewhuge,huge,making
makingassembly
assemblyofof
alltherepresentatives
fromthenational
government,
TEPCO,
andall the representatives from the national government, TEPCO, andlocal
local
government
governmentdifficult.
difficult.

● Redefine the structure of AM
and roles, and disseminate theinformation to all stakeholders.
● Conduct practical training forall stakeholders. Secure alocation for the training.

● Insufficient training for
upper levels in TEPCO,
national government andlocal government.

●●

Although
AlthoughTEPCO,TEPCO,and
andthethenational
nationalandandlocal
localgovernments
governmentshave
havedefined
definedresponse
methods
andconducted
training,
they
weren’table
response methods and conducted training, they weren’t abletotoexecute
executeininaa
timelytimelymannermannerduring
duringthe
theactual
actualemergency
emergencywhich
whicheventually
eventuallyled
ledtotothe
thehydrogen
explosion.
hydrogen explosion.

● Reinforce practical training(emphasis on improving
response speed)● Local response
headquarters (of country,
prefecture, municipalities,etc.) lacked design andtraining in directing andleading an evacuation.

●●

Nuclear
Nucleardisasterdisasterlocal
localresponse
responseheadquarters
headquarterswas
wasnotnotalways
alwaysunified
unifiedinindirecting
directingandleadingtheevacuation.
The
roles
of
the
national
andlocal
and leading the evacuation. The roles of the national and localgovernment
government(prefecture(prefecture&&municipalities)municipalities)were
weredefined
definedbut
butunclear,
unclear,thus
thusineffective.
ineffective.

● Review the structure and role
distribution of local disaster
response● Conduct and reinforce training
for mastery of subject.

●●

DisasterDisasterresponse
responseheadquarters
headquarters(prefecture(prefectureandandmunicipality)
municipality)withwithnuclear
nuclearpower
plantsinitsjurisdiction
havetorespondtonucleardisasters
power plants in its jurisdiction have to respond to nuclear disastersininaddition
addition
totootherotherdisasters
disasterssuch
suchasasfire,
fire,earthquake,
earthquake,and
andflood.
flood.There
Thereneeds
needstotobe
beaa
countermeasurecountermeasuredesigned
designedspecificallyspecificallyfor
fornuclear
nucleardisasters.
disasters.

●●

DuringDuringaanuclear
nucleardisasterdisasterititisiscrucial
crucialtotoobtainobtainandandunderstandunderstandcurrent
current
information,
andpromptly
deliver
response
policiesandmakedecisions.
information, and promptly deliver response policies and make decisions.To
To
achieveachievethis,this,there
theremust
mustbebeaanuclear
nuclearspecialist
specialistininthe
thelocal
localgovernment
government(prefecture(prefectureorormunicipality)
municipality)totoconsult
consultwith.
with.

● Reorganize local structure andresponse plan for multilayered
disasters● Conduct hands-on educationand training● Assign and utilize nuclear
specialist

170

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM system...Current status...Plant...

Extremely Confidential

Current AM Organization (Fukushima Dai-ichi example) : Need to verify whether the power company/
government had the ability and capacity to respond to simultaneous and severe accidents
in multiple plants.
Organization at Fukushima Dai-ichi
Anti-seismic Isolation Tower(Site Superintendent)

Anti-seismic
Isolation
Tower

ControlRoom

1 Unit Superintendent(Reactors 5 - 6)

1 Unit Superintendent(Reactors 1- 4)

Shift Supervisor x1
Assistant Shift
Supervisor x1

Shift Supervisor x1
Assistant Shift
Supervisor x1

Shift Supervisor x1
Assistant Shift
Supervisor x1

Unit 1

Unit 3

Unit 5

Unit 2

Unit 4

Unit 6For each reactor:
・ Senior Operator x 2、 Assistant Senior Operator x 1
・ Main Machinery Operator x 2、 Auxiliary Machinery Operator x 3-5

Current
Currentorganization
organizationofofplant
plantoperation
operation●● Decisions
by
Site
Superintendent:
Decisions by Site Superintendent:Deployment
Deploymentofofpower
powersupply
supplyvehiclesandfiretruckstotheplant.
Execution
of
vent
and
vehicles and fire trucks to the plant. Execution of vent andseawaterseawaterinjection.
injection.Decisions
Decisionsononmattersmattersnot
notdefined
definedininthetheAMAMmanual.
manual.
●● Decisions
Decisionsby
byShift
ShiftSupervisor:
Supervisor:Items
Itemsdefined
definedininAM.
AM.
●● Shift
Supervisor
licenseandtraining
=
Have
to
pass
Shift Supervisor license and training = Have to passthe
theBTC
BTC"lead
operator"
examination.
"lead operator" examination.
IssuesIssues●● Compared
Comparedtotothe
theplant
plantwithwithsingle
singlenuclear
nuclearreactor,
reactor,ititisisbelievedbelieved

that
thatthetherisks
risksininthose
thosewithwithmultiple
multiplereactors
reactorsincrease
increase
dramaticallyifasevereaccident
occurs.
dramatically if a severe accident occurs.
●● AtAtthe
thesamesametime,time,pressurepressureon
onthe
thefield’s
field’smanagement,
management,
theskillsrequired,andtheresponse
speed
the skills required, and the response speedandandaccuracyinsuch
eventsaremuchgreater.
accuracy in such events are much greater.
●● Looking
Lookingatatthe
thechronology,
chronology,it's
it'spostulated
postulatedthat
thatpreparations
preparationsforrespondingtomultiple
units
may
not
have
for responding to multiple units may not havebeen
been
sufficient.
sufficient.

171
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure... Comments from local government…

Extremely Confidential“Regarding the reoperation of the plant, what happened at Fukushima Dai-ichi, including decision
making, has to be examined. Computer simulation that hasn’t taken this into account isunsubstantiated” – Governor of Niigata Pref(*). Izumida *) re: Another nuclear power plant location.
Governor Izumida’s comment (extracted from regular briefing on Sep 14th)●○

Q: What do you think about the government’s announcement
regarding the IAEA’s participation in the evaluation of the stress
test?
Governor: It isn’t enough. What happened in the
Fukushima Dai-ichi isn’t just about the mechanisms andequipment. The decision making mechanism must be
evaluated as well. We need to consider questions such as,
when should the decision to pour seawater have been
made? who should have made the decision? can someone
really make such a decision knowing that he/she is disposing of aplant worth hundreds of billions of yen?
Was there really nothing that could have been done to prevent therelease of a massive amount of radiation? It was pointed out in
IAEA ‘s report that the prime minister was intervening too muchwith the site. Considering this, there isn’t much point in
conducting stress test without reviewing the decision
making mechanism, like who’s responsible for what.
If you ask me if there really is any point in computer
simulations, without even verifying if there was a pipeline
rupture, that is solely based on past knowledge and perception,and then having the IAEA review it, I’d say that it may bebetter than doing nothing at all, but it’s really nothing
more than that.

What it means● Prevention measures must be made from both thetechnical and organizational aspects.
● Technical aspect: Inspect Fukushima Dai-ichi (back fromdesign philosophy), and identify lessons learned andcountermeasures.
● Organizational aspect: Establish an organization to
implement the countermeasures, and clarify therequirement for the decision-making mechanism.
・ Redesign the decision-making mechanism to prioritize preventionof recurrence as top priority.
(Head Office, Technical Support Center, Off-site Center, Central
Control Office)・ Design the organizational structure and identify the roles for the
implementation of the countermeasures (Power company, National
Government, Local Government)● Reinforce training: Practical training necessary forcountermeasures and organizations (that were
established based on the lessons learned) to beeffective.
・ Training program simulating the accident in Fukushima Dai-ichi.
・ Plan and practice program, and improve the results.
・ Case study around the world.

172
In addition to technical measures, accident management systems for local participationin terms of decision-making, organization, and training are required.

Unauthorized copying or distribution of this file is prohibited.
Copyright Team H2O Project all rights reserved

AM structure…Mission…

Extremely Confidential

In order to achieve that, it is very important to incorporate the following missions in
the design of Accident Management.
SafetySafetyPriority
Priority● To protect human life and promote safety culture, create a system that prioritizes “safety of plant”
and “safety of local community” above all.
● Hydrogen explosion and radiation leaks must be prevented at all cost. (Never Fukushima again.)

RealRealtime
time
information
information
sharing
sharingNW
NW● Provide network that allows real-time and transparent information sharing during severe accidents(or risks).
● Create a system that notify the status once the accident mode is on, and that allows information
sharing and discussion regarding the progress of the accident.

Local
Local
participation
participation● System that allows local bodies to share information and make decisions on the safety of the area.
● Enrich human resources of the local administration such as nuclear power specialists and consultants.
● Impel and reinforce training.

Transparent
Transparentand
and
swift
decision
swift decision
makingmaking● Design an organization and authority where proper and transparent governance works.
－ Plant safety: The site (plant head or shift manager) is the chief decision maker.
－ Local safety: The local government can share information from the plant in real-time
to make final decisions.
－ Decision-making process should be transparent and should not be delayed or diverted
due to external influences.

Proper
Propertraining
training
tosecureto securesafety
safety● To guarantee the items above, AM (accident management) procedure manual and countermeasures
have been defined appropriately.
● Select qualified personnel for executing the manual.
● Selected personnel will undergo necessary training.
173● Periodic evaluation on these procedures, personnel, and training shall be conducted from a neutral
point of view (possibly a third party)
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…Information sharing network…

Extremely Confidential

For severe accidents that require prompt action, there needs to be a real-time networkthat enables all the stakeholders to share information and participate in discussion.
FutureCurrent situation (Article 10 In case of accident)

On-site Emergency
Headquarter(at Earthquake
shelter)● Fukushima Pref. Social Affairs & Env’t Dept,
Nuclear Power Safety Div (Governor)● Okuma-city Consumer and Env’t Protection
Div (Mayor)● Futaba-city Citizens' Livelihood Sec (Mayor)● Surrounding cities, towns, and villages● Police, fire department, coast guard

Overall Emergency
Headquarters(Power company)

Emergency
Headquarters(Central government)

Emergency
Headquarters(Prefecture)

Emergency
Headquarters(City/Town/Village)

TV conference
systemOff-site Emergency
Headquarter(at Headquarters
of TEPCO)● Nuclear Emergency Preparedness
Div of NISA at METI (Minister of METI)● Related parties of Ministry of Education● Cabinet Secretariat, Cabinet Office

Confirm receipt of fax by phone
Transmit FAX● Related departments within power company
Phone callContact points indicated in Act on Special Measures Concerning Nuclear Emergency Preparedness Article 10 Section 1● Real-time (limited): Real-time TV conference available between the● Real-time (limited): Real-time TV conference available between the
power plan and Head Office.
power plan and Head Office.
● Bi-directional (partial): Communication other than with government● Bi-directional (partial): Communication other than with government
bodies are mainly one-directional through phone, FAX and mail.
bodies are mainly one-directional through phone, FAX and mail.
● Limited information sharing:● Limited information sharing:・Communication difficulties during power outage and transmission・Communication difficulties during power outage and transmission
problems.
problems.
・
Local government pointed out that information on the accident provided to・
Local government pointed out that information on the accident provided tothem was insufficient (partly because they were using public lines).
them was insufficient (partly because they were using public lines).

Individual Plant'sCentral control room

Local Emergency
Headquarters(Earthquake shelter)

Off-site center・ Dedicated line
・ Emergency power・ Countermeasuresagainst earthquake
and tsunami.
・ Network security, etc.

● System that enables the network to simultaneously connects related● System that enables the network to simultaneously connects related
stakeholders and plants, and help real-time information sharing,stakeholders and plants, and help real-time information sharing,meetings, and decision making.
meetings, and decision making.
・
Stakeholders: Plant, power company’s headquarter, government, prefecture and・
Stakeholders: Plant, power company’s headquarter, government, prefecture andcity/state/province of the plant.
city/state/province of the plant.
・
Function: Share information and hold conference regarding plant status,・Function: Share information and hold conference regarding plant status,
countermeasures, local safety, evacuation, etc.
countermeasures, local safety, evacuation, etc.
・Let stakeholders know that AM (accident management) mode is on, and share・Let stakeholders know that AM (accident management) mode is on, and share
the progress of events.
the progress of events.
・Help transparent and prompt decision-making with all the information shared.
・Help transparent and prompt decision-making with all the information shared.
・Prevent information from leaking.
・Prevent information from leaking.

174

It will be too late to consult with the head office when the accident passes a critical point.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…Governance…

Extremely Confidential

Ensure plant safety: Front line (Plant Head and Unit Manager) shall have absolute authority, and mustgovern the plant with accident prevention and containment as top priority – equivalent toairline’s “air-traffic controller” and “pilot”, or manufacturing’s “CEO” and “Chief Engineer”.
Logistical support to the site
Power company

Shareinformation
Plant

Sh
ov a r e
er- inf
all o osaf nety

Head office or
central government

Head office
Emergency Headquarter

Plant Head
(Earthquake shelter)
Local government

Share info on
local safety

Government

Government
Emergency Headquarter●● Power
Powerplant:
plant:Decisions
Decisionsand
andactions
actionswith
withtoptoppriorities
prioritieson
accident
prevention
andsafety.
On
thisissue,
on accident prevention and safety. On this issue,itit
shouldshouldbebeindependent
independentfrom
frommanagement.
management.

local government●● HeadHeadoffice:office: Entrust
Entrustthe
thesitesitetoto“plant“plantsafety”.
safety”.Provides
Provideslogisticallogisticalsupport
supporttotothe
theplant.
plant.

Prefecture
Emergency Headquarter

Instructions &commands

Shift Manager(Central control room)

Power
PowerCompany’s
Company’sHead
HeadOffice
OfficeandandPlant:
Plant:Separation
Separationofof
SafetySafetyfrom
fromBusinessBusiness

City/Town/Village
Emergency Headquarter

Full authority over the plant's accident response
・ Undefined accident = Plant Head・ Defined accident = Shift Manager on-site

Plant
PlantHead
Headand
andShift
ShiftManager:
Manager:Act
Actas
as‘Traffic‘TrafficController’
Controller’
and‘Pilot’.
and ‘Pilot’.
●● Plant
PlantHead
Head(=(=Traffic
TrafficController):
Controller):・・ Provide
Provideinstructions
instructionstotothe
theshiftshiftmanager
managerininthe
theevent
event
notdefinedintheAccident
Procedure(AM
Manual).
not defined in the Accident Procedure (AM Manual).
・・ HasHasabsoluteabsoluteauthority
authorityand
andresponsibility
responsibilityover
overthethesafety
safetyandandaccident
accidentprevention
preventionofofall
allreactors
reactorsininthe
theplant.
plant.
●● Shift
ShiftManager
Manager (=(=Pilot):
Pilot):・・ Hasabsolute
authority
Has absolute authorityover
overthetheplant’s
plant’ssafety
safetyonon
eventsandoperations
definedintheAM
manual.
events and operations defined in the AM manual.
・・ Shares
Sharesinformation
informationtotostakeholders
stakeholderswhen
whenininAM
AMmode.
mode.

In order to achieve this mission, Plant Head and Unit Managers should go through 175
stricter qualification and trainings, and receive appropriate rewards.

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…Local participation…

Extremely Confidential

We must aim for a decision-making system where the local officials can make decisions
on “the safety of the citizens” as a local autonomy.
Only in extremely severe events, thecentral government shall instruct local
governments for the interests of national
defense.

Power company

Government

Share
information
Plant

Sh
ov a r e
er- inf
all o osaf nety

Head Office orCentral Government

Government
Emergency Headquarter

Head office
Emergency Headquarter

Share info andagreements.

local safety
Prefecture of Power Plant

Shift Manager(Central control room)●● Overwhelmed
Overwhelmedwith
withincomplete
incompleteand
anderroneous
erroneous
information.
information.
●● Delayed
Delayedinformation
information(status(statusofofthe
theaccident,
accident,evacuation,
evacuation,etc.)
etc.)●● Contentsoftheinformation
were
confusing.
Contents of the information were confusing.
●● ItItwas
wasconfusing
confusingwho
whohadhadauthority
authoritytotomake
makedecisions
decisions(accident
response,
evacuation,etc.)(accident response, evacuation, etc.)★★ TheThelocal
localgovernments
governmentshad
hadno
noauthority
authoritytotoparticipate
participateinin
decision-making,sowere
positioned
like“victims”.
decision-making, so were positioned like “victims”.
Ideal role of local government

Prefecture
Plant Head
Emergency Headquarter(Earthquake shelter) Share info on
Instructions &commands

The accident from the local government’s view point

Conference
Discussion
Decision

City/Town/Village
Emergency Headquarter

local government

Understand the situation of the accident so thatdecisions such as whether to evacuate can be made.

●● Decision-making:Decision-making:On
Onlocallocalsafety
safetyandandevacuation,
evacuation,thetheheadheadofof
local
localgovernment
governmentshould
shouldhave
havefullfullunderstanding
understandingofofthe
thesituation
situation
anddiscusswithplant’shead
beforemakingany
final
decision.
and discuss with plant’s head before making any final decision.
●● Training:
Training: Head
Headofoflocal
localgovernment
governmentshould
shouldreceive
receiveconstantconstant
training
trainingtotodevelop
developgood
goodjudgment
judgmentskills.
skills.
●● Information
Informationsharing:
sharing:Information
Informationneededneededtotomake
makedecisions
decisionsshall
shallbebeprovided
provideddirectly
directlyfrom
fromthetheplant
plantrather
ratherthan
thanfrom
fromthethecentralgovernment
orhead
officeofpowercompany.
central government or head office of power company.
●● Network:
Network:There
Thereisisa anetwork
networktotoconduct
conductthese
thesemissions.
missions.
●● Decision
standards:
Basis
on
the
roles
and
responsibilities
Decision standards: Basis on the roles and responsibilitiesofof
thethenational
nationalandandlocal
localgovernment
governmentisisexplicitly
explicitlydefined.
defined.
( Three Mile Island accident in US: One of the reasons the powercompany was able to build a good relationship with the local
government/community was because they involved the locals in theoperations/trainings of the plant after the accident. )Principle is to “Operate the plant safely with the locals”.

176

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…CATO…

Extremely Confidential

In order to achieve that, the local government should strengthen human resources, suchas by hiring a senior officer (CATO*) with expertise on nuclear technology. (* Chief Atomic Technology
Officer)

Future direction (vision)

Mission of CATO

Local Emergency Headquarter

Prefecture
Governor

consult

Country’s
Emergency Headquarter

CATO & otherSpecialist TeamPower company’s
Emergency Headquarter

Share information,
decisions, andinstructions

Media

Local
policedepartment

Local fire
department
head office

Emergency
Headquarter ofcity/village

Other
cities andvillages

Local citizens, ships, vessels in the area, etc.

● The local governor makes overall
judgments while consulting to
CATO and others and act as acontrol tower.

Coast
Guard, etc.

●● Qualifications:
Qualifications:IfIfthethelocal
localgovernor
governordeems
deemsthat
that
he/shewill
havedifficultyinhandling
issuesonhe/she will have difficulty in handling issues onthe
thenuclearpower
plant
accident,
which
requirenuclear power plant accident, which require
technical
technicalknowledge
knowledgeandandexpertise,
expertise,he/she
he/sheshould
shouldassign
a
CATO,
who
is
responsibleforthetechnology
assign a CATO, who is responsible for the technologyand
andsafetyofthenuclear
power
plant
.
safety of the nuclear power plant .
・・ To
Tomaintain
maintainneutrality,
neutrality,CATO
CATOcandidates
candidatesshould
shouldhave
havenono
previous
previousaffiliation
affiliationwith
withthethepower
powercompany
companyororthethegovernment.
government.
・・ ThisThisisisonly
onlysubject
subjecttotoareas
areaswithwithnuclear
nuclearpower
powerplants.
plants.
●● RoleRoleofofCATO:
CATO:To
Tohavehavemeetings
meetingsandandshareshare
information
with
the
power
company,
government,
information with the power company, government,
administrative
administrativeagencies,
agencies,emergency
emergencyheadquarters.
headquarters.
Toadvisetothegovernor.
To advise to the governor.

For example, Niigata Prefecture introduced a new post, “Crisis Manager”, who manages
risks related to the nuclear power plants. - Expenses including training should be 177
shouldered by the central government.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…AM structure…

Extremely Confidential

From now on, we need to manage accidents in 3 categories and establish its own AM
structure.
Responsibility
Accident Category

Accident
Accident

Examples・ Core reactor scram + external
power outage + activation of
emergency generator (DG)

Information
NW
ON

SevereSevereAccident
Accident

Grave
GraveAccident
Accident

Responsibility of “Local Safety”

withingovernment

・ Defined in AM = ShiftManager・ Plant shares information directlywith local government.
・ Local government makes final
decision to evacuate.
・ Central government provides
logistical support and agreement.

Ministry ofEnvironment

・ Not defined in AM = Plant
Head・ Fukushima Dai-ichi Reactor 6,
Tokai Dai-ni, etc.

・ Reactor scram + complete power
outage (DG unavailable)

Responsibility of “Plant Safety”

ON・ Same as above

・ Same as above

Ministry ofEnvironment

ON・ Same as above

・ Central government has authority
to make decisions

Office of
Prime
Minister・ Fukushima Dai-ichi Reactor 5・ Complete loss of power andcooling function
・ Core meltdown, increasing risk ofradioactive leakage
・ Fukushima Dai-ichi Reactors 1 - 4
・ Terrorist attack

・ Central government provides
necessary support(e.g. Self Defense Force
deployment)

・ Central government, after
consulting with local government,
shall make overall decisions fornational defense/national interest.

When the situation reaches extreme level, the central government will takecontrol in order to protect national safety and interests.

178

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…ＧAM judgment…

Extremely Confidential

For example, as to Fukushima Dai-ichi Reactors 1 – 3, wasn’t there a need to judge thelevel and stage of accidents and determine the appropriate actions?
Form

Earthquake& scramExternal AC power
DC power (A),(B)
Emergency DG
Sea water system
2011/3/11

Activate IC/RCICTsunami impact

Fukushima Dai-ichi
Unit 1
Mark 1(BWR-3)

Fukushima Dai-ichi
Unit 2
Mark 1(BWR-4)

Fukushima Dai-ichi
Unit 3
Mark 1(BWR-4)

Fukushima Dai-ichi
Unit 4
Mark 1(BWR-4)In operation

In operation

In operation

Stopped(Regular inspection)

×
×
×
×

×
×
×
×

Earthquake occurred (14:46)
Scram

×
×
×

×
×
×
×

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Earthquake occurred (14:46)

Scram

Scram

IC activated (14:52)

RCIC activated (14:50)/ stopped (15：28)

RCIC activated (15:05)/ stopped (15：25)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)RCIC activated (15:39)

RCIC activated (16:03)○(2 systems)

Tsunami hit(1st wave： 15:27／2nd wave:
15:35)

Core damage begun(18:46). By simulation

Activate
HPCS

Large quantity of hydrogengenerated/accumulated

D/W pressure rise(to 0.84MPa 2:30)

Core damage
start

Hydrogen
explosion(15:36)

RCIC stopped (11:36)

Electrical supply vehicle
damaged (15:36)●● Availability
Availabilityofofpower
power(External(Externalpower,
power,
Emergency
DG,
Battery,etc.)
Emergency DG, Battery, etc.)- - Should
Shouldbebeableabletotocomprehend
comprehendthe
theavailability
availability
ofofallpowersources
so
that
it
can
be
checkedall power sources so that it can be checked
instantly.
instantly.
●● Availability
AvailabilityofofHPCS
HPCSfunctions.
functions.
Possibilityofmalfunction
Possibility of malfunctionand
andestimatedestimatedtiming.
timing.

2011/3/12

HPCS
malfunction

Criteria of Severe Accident (SAM) and Grave Accident(GAM) (illustration)

HPCI activated (12:35)●● Status
Statusofofthe
thecorecorereactor
reactorand
andriskriskofofmeltdown
meltdown
based
on
the
overallavailability
andconditions
based on the overall availability and conditionsofof
thethepower
powerandandcooling
coolingfunctions.
functions.

2011/3/13
HPCI stopped (2:42)↓↓

Core exposure begun(Water level ＝TAF attained
4:15)

Mass accumulationof Hydrogen

Core damage begun(around 8：46). By
simulation
Large quantity of hydrogengenerated/accumulated

Hydrogen back flew
(From Unit 3)

Nuclear reactor
depressurized (Releasesafety valve @ 9:08)
Fresh water injection from fire
trucks begun (with boric acid
9:25)

Hydrogen explosion(Reactor 2 unknown)

SC vent AO valve (large
valve) opened (12:30)

2011/3/14

Radiation leak

Fire trucks damaged (@11:01)

SC vent AO valve (small
valve) opened (5:20)

Loss of cooling function wasdetermined(RCIC stopped (@13:25))

Sea water supply begun fromstorage to reverse valve pit(9:20)

Core depressurized(SRV opened @18:00)

Self Defense Force water supply
vehicles arrive, supplied fresh
water from reverse valve pit(10:53)

Fuel rods completely exposed(Water level＝TAF-3700mm
18:22)

Hydrogen explosion(11:01)★
★ WhenWhenexpected
expectedtotolose
losepower
powerandandcooling
coolingfunctions,theprobability
of
GAM
is
functions, the probability of GAM isvery
veryhigh.
high.
179

Core damage begun(@19:46). By
simulation: Accident stage

Large quantity of hydrogengenerated/accumulated: Severe Accident stage

Sea water injection begun
by fire trucks (19:54): Grave Accident stage★
★ LookingLookingatatthe
thechronology
chronologyofofFukushima
FukushimaDai-ichi
Dai-ichiReactors
1
–
3,
power
outage+HPCS
Reactors 1 – 3, power outage + HPCS
malfunction
malfunctionresulted
resultedininmeltdown
meltdownand
andradioactive
radioactive
leakage.
(+
Hydrogen
explosionon
Reactorsleakage. (+ Hydrogen explosion on Reactors11&&3)3)

2011/3/15

Pressure incontainment vessel S/C
indicated 0MPa (abs)(6:00-6:10)

Hydrogen explosion(6:12)

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…ＩＮＥＳ index…

Extremely Confidential

Government announced level 4 on March 12, level 5 on March 18, and level 7 on April 12.
However, were these really appropriate? (level, timing, frequency, and key message)
Facts and References● The event in Fukushima was the first to ever pass level 5 since the● The event in Fukushima was the first to ever pass level 5 since theestablishment of the International Nuclear Event Scale (INES) in 1989. There wasestablishment of the International Nuclear Event Scale (INES) in 1989. There wasno precedence of an ongoing event to be declared on such a scale.
no precedence of an ongoing event to be declared on such a scale.
・ Chernobyl (April 26, 1986 - Level 7) and Three Mile Island (March 28, 1979 - Level 5) were・ Chernobyl (April 26, 1986 - Level 7) and Three Mile Island (March 28, 1979 - Level 5) werescaled in years after the events.
scaled in years after the events.
● On March 12 15:36, the hydrogen explosion occurred in Dai-ichi Reactor 1. At that
● On March 12 15:36, the hydrogen explosion occurred in Dai-ichi Reactor 1. At thatpoint it should have already met the criterion of level 5.
point it should have already met the criterion of level 5.
・Level 5 = Severe damage to the nuclear reactor core or radiation protection vessels. Requires
・Level 5 = Severe damage to the nuclear reactor core or radiation protection vessels. Requires
planned emergency action.
planned emergency action.
● “The primary purpose of the INES Scale is to facilitate communication and● “The primary purpose of the INES Scale is to facilitate communication andunderstanding …on the safety significance of events.”
understanding …on the safety significance of events.”“INES is a tool for promptly communicating to the public in consistent terms the“INES is a tool for promptly communicating to the public in consistent terms thesafety significance of reported nuclear incidents….” (Extracted from official site of INES)
safety significance of reported nuclear incidents….” (Extracted from official site of INES)● The “impact on people and environment” criterion in Levels 6 and 7 is highly● The “impact on people and environment” criterion in Levels 6 and 7 is highly
subject to interpretation.
subject to interpretation.
・ Level 7: more than several tens of thousands of tera-becquerels (TBq) =>・ Level 7: more than several tens of thousands of tera-becquerels (TBq) =>stochastic health effects over a wide area, perhaps involving more than one
stochastic health effects over a wide area, perhaps involving more than one
country, long-term environmental contamination, and sheltering and evacuation iscountry, long-term environmental contamination, and sheltering and evacuation isnecessary.
necessary.
・ Level 6: thousands to tens of thousands of TBq => sheltering and evacuation is・ Level 6: thousands to tens of thousands of TBq => sheltering and evacuation is
likely.
likely.
・ Level 5: hundreds to thousands of TBq => Localized sheltering and/or evacuation may be
・ Level 5: hundreds to thousands of TBq => Localized sheltering and/or evacuation may belikely.
likely.
● Compared to Chernobyl, the amount of radiation in Fukushima Dai-ichi is around● Compared to Chernobyl, the amount of radiation in Fukushima Dai-ichi is around
10%.
10%.
・ Chernobyl = 5.2 million TBq, Fukushima Dai-ichi = 370,000 TBq (NISA), 630,000 TBq
・ Chernobyl = 5.2 million TBq, Fukushima Dai-ichi = 370,000 TBq (NISA), 630,000 TBq
(NSC)
(NSC)
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Issues and Lessons
●

●

●
●

Was it really necessary to declare the scale 3 times
while the accident was in-progress? (issue withinternational response?)
Learning from the experience in Fukushima, there needs to be
specific guideline in how to declare the scale for progressing
accidents.
In hindsight, the question remains whether the level 4
declared on March 12 23:00 was a technical mistake.
Why was level 7 declared on April 12, one month after
explosion of Dai-ichi Reactors 1 to 4, not right after three
explosions?

●

The accident was still expanding, so instead of justindicating the scale, shouldn’t it have focused on providing
more precise and clear-cut explanations regarding the“impact on people and environment”?

●

The radiation level of Fukushima does fit the level 7
criterion but in terms of “impact on people andenvironment”, which is the original purpose of thescale, the impact is much smaller than Chernobyl. It
seems that level 6 (or a level between 6 and 7) is more
appropriate in this case.

●

Further discussions should be made to review INES criteria
based on what was learned in the Fukushima Dai-ichi Accident
and aim for improvement, especially the criteria for Level 6 and
7 (or modify into detailed scale).
180

Extremely Confidential

AM structure…Message to public…

Was the message to the public appropriate? Wasn’t there a gap between what’s stated
and what actually happened? Doesn't it add anxiety to the local and international society?
Press Conference with the Chief Cabinet Secretary (Sources from various news articles from the web; March 12 onwards)
March 12 18:00 (Reactor 1 after the explosion)
March 12 18:00 (Reactor 1 after the explosion)
・
・

・
・

“Does it mean there was no damage to the nuclear reactor? Has it been confirmed?” => I would like to answer that once
“Does it mean there was no damage to the nuclear reactor? Has it been confirmed?” => I would like to answer that once
we have clarified the details, including final confirmation of facts and analysis of the cause.
we have clarified the details, including final confirmation of facts and analysis of the cause.
“Does the government expect the hydrogen explosion and radiation leak?” => We are handling this matter while“Does the government expect the hydrogen explosion and radiation leak?” => We are handling this matter while
expecting the worst. This accident, when it occurred, was within the scope of our expectations…. Comments
expecting the worst. This accident, when it occurred, was within the scope of our expectations…. Commentsthat give out a false sense of alarm or security must not be made.
that give out a false sense of alarm or security must not be made.

Issues & lessons learned● When should public statements
be made?
● Was the hydrogen explosion
really anticipated?

March 13 (Regarding Reactor 1 and 3)
March 13 (Regarding Reactor 1 and 3)
・

・

・

・

・
・

・
・

・

・

・

・

・
・

・
・

8:00: In regards to Reactor 1, we have confirmed that the filling of seawater is working well as it would with the pump. …we
8:00: In regards to Reactor 1, we have confirmed that the filling of seawater is working well as it would with the pump. …wecan logically conclude that the core is now filled with seawater, or at the least filled to a level that covers the
can logically conclude that the core is now filled with seawater, or at the least filled to a level that covers thefuel rods.
fuel rods.
8:00: (regarding reactor 3) … By this ventilation and water injection with the pump, we should be able to manage,
8:00: (regarding reactor 3) … By this ventilation and water injection with the pump, we should be able to manage,
secure and control the situation, although there will be some level of radioactive materials in the gas it will have no effectsecure and control the situation, although there will be some level of radioactive materials in the gas it will have no effecton the health, and will insure nuclear reactor safety.
on the health, and will insure nuclear reactor safety.
8:00: “At what time will the filling of seawater end?” => Even if we’re done pouring water into the pressure tank
8:00: “At what time will the filling of seawater end?” => Even if we’re done pouring water into the pressure tankand core reactor, we’d also like to fill-up the containment vessel …if we continue filling the pressure tank, it will
and core reactor, we’d also like to fill-up the containment vessel …if we continue filling the pressure tank, it will
overflow, meaning the water will be going outside, so we would like to continue filling it with water.
overflow, meaning the water will be going outside, so we would like to continue filling it with water.
11:00: (regarding Reactor 3) ….water pump stopped functioning… It is presumed that water level on the fuel rods dropped,
11:00: (regarding Reactor 3) ….water pump stopped functioning… It is presumed that water level on the fuel rods dropped,
exposing the top of the fuel rods. Because of this, the safety valve of the pressure tank opened and the pressure in the nuclear
exposing the top of the fuel rods. Because of this, the safety valve of the pressure tank opened and the pressure in the nuclear
reactor dropped. Pumping of water started at 9:08. At 9:25 we mixed boric acid to increase the safety even more.
reactor dropped. Pumping of water started at 9:08. At 9:25 we mixed boric acid to increase the safety even more.
11:00 “What is the status on the exposed fuel rods in Reactor 1?” => We believe that water have been filled, so it’s no
11:00 “What is the status on the exposed fuel rods in Reactor 1?” => We believe that water have been filled, so it’s nolonger exposed.
longer exposed.
11:00: “Does it mean that core meltdown occurred in Reactor 1?” => There is a possibility. Although we
11:00: “Does it mean that core meltdown occurred in Reactor 1?” => There is a possibility. Although we
can’t confirm, since of course we can’t see inside the reactor, it is very likely so we are handling the situation
can’t confirm, since of course we can’t see inside the reactor, it is very likely so we are handling the situation
with the assumption that it did occur.
with the assumption that it did occur.
11:00: “Reactor 1 exploded soon after the ventilation. What about reactor 3?” => This time we were able to
11:00: “Reactor 1 exploded soon after the ventilation. What about reactor 3?” => This time we were able toproperly inject the water and to set up the vent.
properly inject the water and to set up the vent.
11:00: “Have you already prepared what to do in case Reactor 1 can’t no longer be filled with seawater?” => We believe that,
11:00: “Have you already prepared what to do in case Reactor 1 can’t no longer be filled with seawater?” => We believe that,
although it was at the last moment, we were able to fill the reactor with seawater before the problem got any
although it was at the last moment, we were able to fill the reactor with seawater before the problem got any
bigger. For the other reactors, we’d like to do the same and be prepared at all times.
bigger. For the other reactors, we’d like to do the same and be prepared at all times.

● What was the basis for the
methods used for the vent andwater injection when planningand executing it?
● Didn’t they anticipate severe
damage of pressure vessel andwater to leak to the containment
vessel?
● At this point, did they prepare
the way to restore power and tocool the core in reactor 3?
● Was the countermeasure to
explosion in reactor 3 really181
prepared?

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

AM system...Message to the citizens...

(continued - 2)
Issues and Lessons

Press conference with Chief Cabinet Secretary (extracted from 3/12 onwards)
3/13 (About Unit 1 and Unit 3)
3/13 (About Unit 1 and Unit 3)
・

・

・

・
・

・

・
・

・

・

・

・

・
・

・

・
・

・

15:30 As for Unit 3, the water level was found to be low this morning so we have depressurized the reactor and have
15:30 As for Unit 3, the water level was found to be low this morning so we have depressurized the reactor and havestarted with the fresh water injection. By doing so, we were able to restore the water level of the reactor so that it canstarted with the fresh water injection. By doing so, we were able to restore the water level of the reactor so that it canbe cooled. …after that, due to trouble with the fresh water pump, the water level inside the reactor significantly
be cooled. …after that, due to trouble with the fresh water pump, the water level inside the reactor significantly
decreased. … we switched to seawater injection and the water level stably started ascending again. … also, as for
decreased. … we switched to seawater injection and the water level stably started ascending again. … also, as for
Unit 3 , we would like to promptly report the possibility of hydrogen explosion similar to Unit 1. …In
Unit 3 , we would like to promptly report the possibility of hydrogen explosion similar to Unit 1. …In
the event of explosion like yesterday, we can say the nuclear reactor unit, reactor pressure vessel, and the containment
the event of explosion like yesterday, we can say the nuclear reactor unit, reactor pressure vessel, and the containment
vessel will not be affected because the explosion occurred in the outer area, and the structure is designed to withstandvessel will not be affected because the explosion occurred in the outer area, and the structure is designed to withstandsuch impact.
such impact.
15:30 “Is there any way to remove the accumulated hydrogen ?” = > The difference from yesterday is,
15:30 “Is there any way to remove the accumulated hydrogen ?” = > The difference from yesterday is,this time the ventilation was working and letting out the gas. In the current situation it is possible
this time the ventilation was working and letting out the gas. In the current situation it is possiblethat it is already vented out.
that it is already vented out.
15:30 “Is Unit 3 in meltdown? => We have to be careful with our words here. We cannot deny the
15:30 “Is Unit 3 in meltdown? => We have to be careful with our words here. We cannot deny thepossibility of partial deformation of the reactor core. We are certain that the fuel rods were exposed above the coolant
possibility of partial deformation of the reactor core. We are certain that the fuel rods were exposed above the coolant
for a certain period of time. However, generally, the core was not exposed long enough to cause
for a certain period of time. However, generally, the core was not exposed long enough to cause
meltdown. The water level has started rising again.
meltdown. The water level has started rising again.
15:30 “How much has the water level descended?” => It was once exposed significantly. However, the water level
15:30 “How much has the water level descended?” => It was once exposed significantly. However, the water levelhas started ascending so the time of exposure was very limited.
has started ascending so the time of exposure was very limited.
5:30 “How is the progress of removing hydrogen from the building going?” => Basically the process
5:30 “How is the progress of removing hydrogen from the building going?” => Basically the process
to remove hydrogen outside has been ongoing from the start.
to remove hydrogen outside has been ongoing from the start.
20:00 (regarding Unit 3) initially the water level increased when the seawater injection started but later the reactor
20:00 (regarding Unit 3) initially the water level increased when the seawater injection started but later the reactor
pressure vessel’s gauge did not indicate any increase. However, we are still continuing to supply seawater. … There ispressure vessel’s gauge did not indicate any increase. However, we are still continuing to supply seawater. … There isa high possibility that the valve in Unit 3 is defective. We are working hard to resolve the issue with the defect anda high possibility that the valve in Unit 3 is defective. We are working hard to resolve the issue with the defect andlower the air pressure inside the reactor.
lower the air pressure inside the reactor.
20:00 “Is there possibility of explosion (Unit 3) like in Unit 1? => We think that the condition may be
20:00 “Is there possibility of explosion (Unit 3) like in Unit 1? => We think that the condition may bebetter than yesterday. Because, we know the hydrogen has leaked to outside at a point.
better than yesterday. Because, we know the hydrogen has leaked to outside at a point.
20:00 “You said that the water level of Unit 3 is not ascending, what is the status of the exposed
20:00 “You said that the water level of Unit 3 is not ascending, what is the status of the exposed
fuel rods?” => We are currently analyzing the situation with the possibility of the core exposure of course.
fuel rods?” => We are currently analyzing the situation with the possibility of the core exposure of course.
We are currently doing everything we can to quickly solve the issue of the faulty valve.
We are currently doing everything we can to quickly solve the issue of the faulty valve.
20:00 “What are the possible scenarios when the air pressure is this high?” => The present situation,
20:00 “What are the possible scenarios when the air pressure is this high?” => The present situation,
we are not in immediate danger. However, we cannot afford to prolong this situation.
we are not in immediate danger. However, we cannot afford to prolong this situation.

● Didn’t they know that the RCIC and
HPCI had already stopped at thispoint?
● Didn’t they know that since thehydrogen leaked into the building fromthe containment vessel, the relief
safety valve has little effect to preventa hydrogen explosion?
● Although it is a delicate topic, they
ended up giving a false sense of
security which resulted in opposite
affect. (Especially with the local
residents and overseas media, andwith evacuation decision of foreign
governments).

182
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

AM system...Message to the citizens...

(continued - 3)
Press conference with Chief Cabinet Secretary (extracted from 3/12 onwards)
Issues and Lessons
3/14 (regarding Unit 3 and Unit 2)
3/14 (regarding Unit 3 and Unit 2)
・10:55 “You said earlier that the valve in Unit 3 was faulty. Is there any update in the・10:55 “You said earlier that the valve in Unit 3 was faulty. Is there any update in thestatus of repair from now on? => Currently the pressure is low, so instead of attempting
status of repair from now on? => Currently the pressure is low, so instead of attempting
to force the valve open, it will be better to continue the cooling of reactor with water
to force the valve open, it will be better to continue the cooling of reactor with water
injection… (★★Unit 3 explodes★★）…we received news now. At 11:05 there may be smoke
injection… (★★Unit 3 explodes★★）…we received news now. At 11:05 there may be smoke
coming out from Unit 3. We are currently confirming whether there was an explosion.
coming out from Unit 3. We are currently confirming whether there was an explosion.
・10:55 “Is the core meltdown continuing in Unit 1? Is the condition getting worse or is it improving?” =>・10:55 “Is the core meltdown continuing in Unit 1? Is the condition getting worse or is it improving?” =>At this point, since the pressure is not increasing, the water is filled sufficiently and core meltdown is
At this point, since the pressure is not increasing, the water is filled sufficiently and core meltdown is
no longer progressing. If the pressure increases, there is that possibility…
no longer progressing. If the pressure increases, there is that possibility…
・11:40 Explosion occurred a while ago at 11:01 in Unit 3. Judging from the condition of the・11:40 Explosion occurred a while ago at 11:01 in Unit 3. Judging from the condition of the
explosion, it is thought to be a hydrogen explosion similar to that of Unit 1… the Plant
explosion, it is thought to be a hydrogen explosion similar to that of Unit 1… the Plant
Superintended at site has reported that his understanding is that the containment
Superintended at site has reported that his understanding is that the containment
vessel is intact.
vessel is intact.
・11:40 “What is the basis of stating that the containment vessel is not affected?” =>・11:40 “What is the basis of stating that the containment vessel is not affected?” =>Based on the data we received (to Tokyo), water injection is ongoing, or within theBased on the data we received (to Tokyo), water injection is ongoing, or within thespecified range, although the values may be slightly low. ...this is based on the reportspecified range, although the values may be slightly low. ...this is based on the report
given directly by the Plant Superintendent.
given directly by the Plant Superintendent.

● Aren’t they too fixated on the safetyof the containment vessel?

・12:40 The pressure inside the containment vessel is stable - 380 kilo Pa at 11:13 and 360 Pa at 11:55. …
・12:40 The pressure inside the containment vessel is stable - 380 kilo Pa at 11:13 and 360 Pa at 11:55. …
I think this proves that there is no problem.
I think this proves that there is no problem.
・12:40 “Are there other plants with hydrogen accumulated in upper levels of the・12:40 “Are there other plants with hydrogen accumulated in upper levels of thebuilding?” => At this point, there is no such risk. We are working hard to prevent such abuilding?” => At this point, there is no such risk. We are working hard to prevent such asituation from happening.
situation from happening.
・12:40 “You mentioned that the pressure decreased at the time of the explosion. Is it not related to the・12:40 “You mentioned that the pressure decreased at the time of the explosion. Is it not related to the
explosion?” => It means the pressure is maintained to a certain degree, and data is available toexplosion?” => It means the pressure is maintained to a certain degree, and data is available tosupport that it is intact as reported by the Plant Superintendent. This is the current situation.
support that it is intact as reported by the Plant Superintendent. This is the current situation.
・12:40 “Isn’t there an effective way to let out the hydrogen accumulated in the building?”
・12:40 “Isn’t there an effective way to let out the hydrogen accumulated in the building?”=> We have received the report that they have deliberated on various options, but if we=> We have received the report that they have deliberated on various options, but if wetouch it there may be a risk of triggering an explosion.
touch it there may be a risk of triggering an explosion.

● To what extent had the response
headquarters evaluated the risk ofhydrogen explosion of Unit 4 and S/Cdamage on Unit 2 at this point (which
occurred in the next day)?
● As a result, hasn’t this amplified the fearof the public?

183
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

AM structure... Message to the citizens…

(continued - 4)
Press conference with Chief Cabinet Secretary (extracted from 3/12 onwards)
3/24 (Regarding Unit 1)
3/24 (Regarding Unit 1)
・ 11:00 “About Unit 1, what is your understanding regarding damage or risk of・ 11:00 “About Unit 1, what is your understanding regarding damage or risk ofdamage to the core and reactor pressure vessel?” => we have received report thatdamage to the core and reactor pressure vessel?” => we have received report that
there is no damage to the pressure vessel at this point.
there is no damage to the pressure vessel at this point.
3/28 (Regarding damage to the pressure vessel)
3/28 (Regarding damage to the pressure vessel)
・ 16:00 “The NSC commented on the cause of the water leak in Fukushima Dai-ichi
・ 16:00 “The NSC commented on the cause of the water leak in Fukushima Dai-ichi
and the possibility of damage to the primary containment vessel (PCV). On theand the possibility of damage to the primary containment vessel (PCV). On theother hand, TEPCO pointed out that the damage is to the reactor pressure vesselother hand, TEPCO pointed out that the damage is to the reactor pressure vessel(RPV). What are the facts?” => We received a report that there is water leaking from
(RPV). What are the facts?” => We received a report that there is water leaking fromthe PCV. …We have not received a report on the details of the RPV.
the PCV. …We have not received a report on the details of the RPV.
・・

16:00 “If the water that had contact with the molten fuel is leaking outside the
16:00 “If the water that had contact with the molten fuel is leaking outside thePCV, isn’t it normal to think that it leaked from RPV?” => I think that explanation
PCV, isn’t it normal to think that it leaked from RPV?” => I think that explanation
by someone with expertise with nuclear reactors is more accurate. Of course,
by someone with expertise with nuclear reactors is more accurate. Of course,
since the fuel rods are inside the RPV the water that had contact with it had
since the fuel rods are inside the RPV the water that had contact with it had
somehow moved …
somehow moved …

Issues and Lessons● They are too worried about how it willaffect (or receive criticism from) the local
and international society if they admitted
to the “Meltdown”. Wouldn’t they havebeen able to provide a reasonable
explanation only if they had first admitted
to crucial incidents such as the damage tothe reactor pressure vessel, damage tothe primary containment vessel, andmelting of the fuel rod?
● Consequently, they were unable toestablish a reasonable andunderstandable frame work for disclosing
messages and risks to the citizens. Thus
ending up the awkward explanation.

4/19 (Regarding Units 2 and 4 meltdown)
4/19 (Regarding Units 2 and 4 meltdown)
・ “Yesterday, NISA admitted that the fuel rod had melted, which it had been
・ “Yesterday, NISA admitted that the fuel rod had melted, which it had been
denying till then. However they denied the core meltdown. Is there any basis fordenying till then. However they denied the core meltdown. Is there any basis forthis? => It is a very technical process, so please ask NISA regarding this matter.
this? => It is a very technical process, so please ask NISA regarding this matter.
However, I have been saying that there may be a chance, or it is likely that a
However, I have been saying that there may be a chance, or it is likely that a
portion of the fuel rods are damaged. However judging by the monitoring reports
portion of the fuel rods are damaged. However judging by the monitoring reports
in the field, we can say that it hasn’t entirely melted and there is no big hole inin the field, we can say that it hasn’t entirely melted and there is no big hole inthe core. As for the degree of the damage to the fuel rods, and whether there isthe core. As for the degree of the damage to the fuel rods, and whether there ispartial meltdown, that is being analyzed by specialists in NISA and the Safety
partial meltdown, that is being analyzed by specialists in NISA and the Safety
Committee. We simply receive the reports from them.”
Committee. We simply receive the reports from them.”

184
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…Government safety guidelines…

Extremely Confidential

The government’s safety guideline has been incorrect – “No need to consider long-termloss of power.”
Nuclear Safety Commission’s Design Guidelines(Supervised by Cabinet Office Nuclear Safety Commission Secretariat)

Section 1: Safety Review Guideline No. 27 “In case of power loss"● Nuclear reactors and facilities should be able to safely stopand secure cooling function in case of a short-term lossof all AC power.
(Explanation)

Facts at Fukushima Dai-ichi● Transmission line was not restored
before hydrogen explosion.
● Emergency AC power supply system
malfunctioned due to the tsunami andwas not restored before the hydrogen
explosion.

● There is no need to consider long-period loss of AC power,
since we can expect swift restoration of the transmission
line or restoration of power through the emergency AC
power supply system.

● Not only the AC power, but also the
DC power supply were completely lostfor a long period.

● If the system structure or operational method (i.e. constantbackup) of the emergency AC power-supply system is deemed
highly reliable, then there is no need to take into accountany scenario of a complete AC power blackout in thedesign of the plant.

● Due to the complete loss of all AC andDC power for a long period, key
functions such as parameter-control at
the central operation room, cooling,
and water-injection were all lost.

It is necessary to verify why and who is responsible for this guideline, and completely
185
redesign the atomic energy administration, as known for its back-scratching structure.

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…On-site and off-site boundaries…

Extremely Confidential

It is imperative to provide clear safety guidelines for long-term power loss. For example, if
it is over 24 hours, off-site support shall be provided, and if within 24 hours, the on-siteteam has to deal with it.
Length of AC power outage

Guideline

Main player
Power supply

24 hours● Prepare on-site plan and safetymeasures that can prevent coredamage for at least 24 hours for any
type of power loss.

● For power loss over 24 hours, off-site
support and actions shall be made.

● Power company● Power company and central government● Secure power supply on-site for atleast 24 hours.

● Must accomplish off-site support within
24 hours.

● In US, boundary between on-site and off-site response is 72 hours for NRC and 24 hours for INPO.
● For example, USA has a special unit that is intensively trained to work in radiation-contaminated areas (e.g. Fort
Leonard Wood Chemical Biological Radioactive Unit).
● Japan should have a similar special unit as well.

186

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

AM structure…Education and training…

Extremely Confidential

Future education and training should include ‘lessons learned from Fukushima Dai-ichi’.
Important items for the education and training programs (Example)●● Practical
Practicaltraining
trainingunder
underextreme
extremeconditions
conditionssuch
suchasasin
inFukushima
FukushimaDai-ichi
Dai-ichiReactor
Reactor11
・・ Complete
Completepower
poweroutage,
outage,losslossofofcooling
coolingfunction,function,darkness,darkness,aftershocks,
aftershocks,highhighradiation,
radiation,insufficientinsufficientmaterials,
materials,and
andtelecommunication
telecommunicationproblems.
problems.
・・ RiskRiskofofcore
coredamage
damageandandhydrogenhydrogenbuild-up
build-upininaacouple
coupleofofhours
hoursfromfromthethestopstopofofcooling
coolingsystem.
system.
・・ (Furthermore)
Severeaccident
duringholidays,night,
bad
weather,
fire,
and
road
blocks(simultaneously).
(Furthermore) Severe accident during holidays, night, bad weather, fire, and road blocks (simultaneously).
・・ Emphasis
Emphasison
onthe
theabsoluteabsoluteprevention
preventionofofaahydrogenhydrogenexplosion
explosionunder
underanyanycircumstances.
circumstances.
●● Practical
Practicaltraining
trainingto
tosupply
supplyalternative
alternativepower
powersource
sourceandandcooling
coolingsystemsystemto
tothe
theplant
plant(for(forexample)example)“within“within22hours”
hours”during
duringcomplete
completepower
poweroutage
outage・・ Prepare
and
store
the
requirements.
(Define
the
type
and
quantity
Prepare and store the requirements. (Define the type and quantityofofpower/water
power/watersources
sourcesand
andequipments
equipments
totomeetthenecessarytimeofcooling.)meet the necessary time of cooling.)
・・ Actual
Actualoperation
operationtotocarry
carryandandsetsetup
upalternative
alternativesystems
systemssuch
suchasaspower
powersupply,
supply,coolant,
coolant,water-injection,water-injection,
carry-onbatteries
on-site.
carry-on batteries on-site.
・・ Organize
Organizeand
andoperate
operatesupply
supplychainschainsfor
foremergency
emergencyequipment
equipment(at(atthetheplant,
plant,atatthe
theheadheadoffice,office,etc.)
etc.)
●
● Set
Setspecificspecificindicators/goals/periods
indicators/goals/periodsin
ineacheachtraining
trainingand
andcheckcheckits
itsproficiency
proficiencylevel.
level.
・・ Example:
ProvideX
amountofpower/watersupplywithinY
hours.
CompletetaskAwithinB
Example: Provide X amount of power/water supply within Y hours. Complete task A within Bhours,
hours,etc.
etc.
●● Practical
Practicaltraining
trainingnot
notonly
onlyforforthethepower
powercompany,
company,butbuttogether
togetherwith
withthethecentral
centralandandlocal
local
government
governmentand
andrelated
relatedstakeholders.
stakeholders.
●187all● ShareShareandandpass
passdown
downthetheexperience
experienceand
andlessons
lessonslearned
learnedfrom
fromFukushima
FukushimaDai-ichi
Dai-ichiwith
with
all
power
companies
in
Japan
and
the
world.
power companies in Japan and the world.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Additional
AdditionalResearch
Research
Hearings
Hearingswith
withlocal
localgovernments
governments

188
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Additional Research: Introduction

In this chapter, we summarized the results of additional research
conducted after the interim report on October 28, 2011, on major issues
pointed out by officials of local governments during our interviews.

189
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Summarizing Issues

Extremely Confidential

Summary: We have investigated the following four issues which were frequently
indicated or questioned during our interview sessions with local governments.

●● Why
Whydiddidthetheaccident
accidentininreactor
reactorNo.
No.11progress
progressmuch
muchfasterfasterthan
thanNo.
No.2,2,33andand44ininFukushima
FukushimaDaiDaiichi?
ichi?
Issue
Issue1:1: IsIsititbecause
becausesome
someofofthethemajor
majorpipes
pipesofofthe
thereactor
reactorwas
wasruptured
rupturedby
bythe
theearthquake?
earthquake?
Issue
Issue2:2: IsIsititbecause
becausethe
theprimaryprimarycontainment
containmentvessel
vesselofofreactor
reactorNo.
No.11isisthetheoldoldmodelmodel‘Mark‘MarkI’?
I’?
Issue
Issue3:3: Otherwise,
Otherwise,thetheemergency
emergencycooling
coolingfunction
function(Isolation(IsolationCondenser:
Condenser:IC)IC)should
shouldhave
have
functioned
andtheaccident
development
should
have
been
much
slower.
functioned and the accident development should have been much slower.
●● Issue
Issue4:4: What
Whatcould
couldhave
havebeen
beendonedonetotoreactor
reactorNo.1
No.1ininorder
ordertotoavoid
avoidthethehydrogenhydrogenexplosion
explosionand
andleakageleakageofofradioactive
radioactivematerials?
materials?

In the following pages, key findings are discussed in regards to those issues.

190

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 1

Extremely Confidential

Issue 1: The accident in reactor No. 1 progressed much faster than No. 2, 3 and 4, becausesome of the major pipes in the reactor were ruptured by the earthquake. – This hypothesis
was analyzed from the following perspectives.
What
Whatkindkindofofpiping
pipingsystem,
system,ififruptured,ruptured,cancansignificantly
significantlyaccelerate
acceleratethe
thecorecoremeltdown?
meltdown?Why?
Why?
・・
・・

Pipes
Pipeswithwithlarge
largediameters
diameterssuch
suchasasthe
theoneoneforformainmainsteamsteamcirculation,
circulation,forforfeeding
feedingand
andre-circulating
re-circulatingthe
thecoolant
coolant
Besides
theabove,
nozzlesofconnection
pipes
such
as
the
one
for
instrumental
measurement.
Besides the above, nozzles of connection pipes such as the one for instrumental measurement.

IfIfthese
thesepiping
pipingsystems
systemswere
weretotorupture,rupture,howhowwould
wouldthetheparametersparametersininthe
thereactor
reactorrespond?
respond?
・・

IfIfthetherupture
rupturecauses
causesthetheleakleakofofcoolant
coolantwater
watertotothe
theprimaryprimarycontainment
containmentvessel
vessel(PCV),(PCV),thethefollowing
followingchanges
changeswould
wouldbebeobserved
observedininthe
thepressure,water
level,
andtemperatureofthereactorpressure
vessel
(RPV)
and
the
PCV.
pressure, water level, and temperature of the reactor pressure vessel (RPV) and the PCV.
－－ Pressure
Pressureandandwaterwaterlevel
levelininthe
thereactor
reactorpressurepressurevessel
vesselwould
woulddrop
droprapidly.
rapidly.
－－ Water
level
of
the
condensed
water
tank
in
the
containment
vesselwould
Water level of the condensed water tank in the containment vessel wouldrise
riserapidly.
rapidly.
－－ Pressure
andtemperatureinthecontainment
vessel
would
rise
as
well.
Pressure and temperature in the containment vessel would rise as well.
－－ InInall
allcases
casesabove,
above,alarms
alarmswould
wouldbebetriggered
triggeredby
bythe
thedetection
detectioninstruments.
instruments.

What
Whatwere
werethetheactual
actualresponses
responsesof
ofthe
theparameters,
parameters,compared
comparedto
tothe
thepoints
pointsabove?
above?

・・
・・

Water
Waterlevel
leveland
andpressurepressureininthe
thereactor
reactorpressurepressurevessel
vesselrecovered
recoveredfrom
fromthetheearthquake
earthquaketotothe
thetsunami.
tsunami.
No
significant
riseintemperatureandpressure
inthecontainment
vesselwere
observedthoughNo significant rise in temperature and pressure in the containment vessel were observed thoughthere
therewere
weresomesomeeffects
effectsfrom
fromthetheshut
shut
down
of
the
air-conditioning
equipment.
down of the air-conditioning equipment.

What
Whatkindkindofofdamagedamagewould
wouldworkers
workerssuffer
sufferififthey
theywere
wereexposed
exposedto
tothe
thewaterwater(steam)(steam)fromfromthetheruptured
ruptured
pipe?
pipe?
・・
・・

IfIfthetherupture
ruptureoccurredoccurredininthe
thereactor
reactorbuilding,building,steam
steamofof70
70Atm
Atmandand280280Celsius
Celsiusdegree
degreewould
wouldblow
blowout.
out.IfIfworkers
workerswere
weresubjectedsubjectedtotothe
the
steam
directly,
they
would
be
killedorseverely
injured.
steam directly, they would be killed or severely injured.
Also,
Also,thetheextreme
extremevolume
volumeofofsteam
steamwould
wouldfill
fillthethebuilding,building,making
makingthe
thesurrounding
surroundingarea
areafoggy
foggywithwithzero
zerovisibility.
visibility.Therefore,
Therefore,one
onemustmust
contact
staff
outsidebynecessity.
191
contact staff outside by necessity.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 1

Extremely Confidential

Issue 1: What kind of piping system, if ruptured, could accelerate core damage
significantly? why?
What kind of piping system, if
ruptured, could accelerate coredamage significantly?

Steam
RPV Body Flange
Steam-Water Separator

Shroud(Divider Plate)

Fuel
Control Rods

Control Rod
Drive System●● TheThefollowing
followingpipes
pipeswithwithlarge
large
diameterswouldsignificantly
diameters would significantly
accelerate
acceleratecore
coredamage:damage:・・ Main
MainSteam
SteamExit
ExitNozzle
Nozzle・・ MainSteam
Feedwater
Main Steam FeedwaterNozzle
Nozzle・・ Recirculating
RecirculatingWater
WaterEntrance
Entrance
・・ Recirculating
RecirculatingWater
WaterExit
Exit(Besides, pipe connectors such as the one for(Besides, pipe connectors such as the one for
instrumental measurement would also be
instrumental measurement would also be
considered. )considered. )●● IfIfthese
thesepipes
pipesareareruptured,ruptured,thethefollowing
followingphenomena
phenomenawould
wouldbebeinduced.
induced.
・・ Steam
Steamininthe
thecorecorewould
wouldbeberapidly
rapidlydischarged
fromthereactorpressuredischarged from the reactor pressure
vessel.
vessel.
・・ Coolant
Coolantwater
waterwould
wouldbeberapidly
rapidlydischarged
fromthereactordischarged from the reactorpressurepressure
vessel.
vessel.

●● As
Asaaresult,result,thethecooling
coolingfunction
functionandandwaterwaterinjection
injectionofofthe
thecorecore
would
wouldbebesignificantly
significantlydamaged,
damaged,which
would accelerate the core
which would accelerate the coredamage.
damage.

So, how did these parameters actually respond?

If rupture occurs, how doparameters in the reactor respond?
●● Water
WaterLevel
Level
・・ Water
Waterlevel
levelininthe
thereactor
reactorpressurepressure
vesselvesselwould
woulddrop
droprapidly.
rapidly.
・・ Water
Waterlevel
levelofofthe
thesumpsump(tank)(tank)inin
containment
containmentvessel
vesselwould
wouldriseriserapidly
rapidly
and
the
alarm
would
be
triggered.
and the alarm would be triggered.
●● Pressure
Pressure&&Temperature
Temperature
・・ Pressure
Pressureininthe
thereactor
reactorpressurepressurevessel
vesselwould
drop
rapidly.
would drop rapidly.
・・ Pressure
Pressureandandtemperaturetemperatureininthe
thecontainment
containmentvessel
vesselwill
willincrease
increase
rapidlyrapidlyand
andthethealarm
alarmwill
willbebetriggered.
triggered.
(Steam(Steamaroundaround280
280Celsius
Celsiuswill
willbebe
ejected.)ejected.)●● Radiation
RadiationDosage
Dosage・・ Radiation
Radiationdosage
dosagewithin
withinthe
thecontainment
vesselwould
containment vessel wouldincrease
increase
rapidly
and
the
alarm
would
rapidly and the alarm wouldbebe
triggered.
triggered.(CAMS(CAMSetc.)
etc.)

192
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 1

Extremely Confidential

Issue 1: The parameters from the time of earthquake to tsunami indicate no significant
changes in water level, temperature, and pressure. No symptoms of pipe rupture
accelerating the core damage.
●● Volume
SteamFlow:
Flow:Had
Haddropped
droppedandandVolumeofofMain
MainSteamstayedstayedatatzero
zerolevel
leveldue
duetotoclosure
closureofofmain
mainsteam
steam
isolation
isolationvalve
valveclosed
closedright
rightafter
afterearthquake.
earthquake.(No
(No
rapid
increaseinflow
volume)rapid increase in flow volume)

Volume of Main Steam Flow

Water Level in Reactor●● Water
WaterLevel
LevelininReactor：
Reactor：Had
Hadstayed
stayedconstantconstant
after
afterinstantinstantshift
shiftcaused
causedby
bycollapse
collapseofofbubbles
bubblesright
right
after
the
scram.
(No
rapid
decreaseinwater
after the scram. (No rapid decrease in waterlevel)
level)

Pressure in Reactor●● Pressure
PressureininReactor:
Reactor:Had
Hadincreased
increaseddue
duetotoclosureclosureofofmain
mainsteamsteamisolation
isolationvalve
valveand
anddecay
decayheat,
heat,
after
decreasing
right
after
the
scram.
after decreasing right after the scram.
・・ AroundAround14:52,
14:52,ititdecreased
decreasedwhen
whenIsolation
Isolation
Condenser
Condenser(IC)(IC)started
startedcooling,cooling,thenthenincreased
increasedagain
again
with
the
stop
of
IC.
(No
rapid
decreaseinwith the stop of IC. (No rapid decrease inpressure)pressure)Difference in pressure
between PCV andsuppression chamber(SC)

Pressure in primarycontainment vessel(PCV)
Difference in pressure
between SC and PCV

1 14：46 Scram started after earthquake.
2 Increase in pressure difference between
SC and PCV, caused by the rise inpressure in PCV.
3 Increase in pressure in PCV, caused by
the stop of air-conditioner in PCV.
4 Decrease in pressure in SC, caused bycooling of SC. (The difference
increased further.)●● Difference
Differenceininpressurepressurebetween
betweenPCV
PCVandandsuppression
suppressionchamberchamber(SC):(SC): Had
Hadincreased
increased
approx.
approx.20-30
20-30kPa
kPaduring
duringthe
theearthquake
earthquakeand
andTsunami.
Tsunami.
Pressure
Pressureincrease
increasewas
wasslight,
slight,andandisisalmost
almostequivalentequivalenttotothe
theriseriseinintemperaturetemperaturecaused
caused
by
the
stop
of
air-conditioner.
by the stop of air-conditioner.
InIncasecaseofofguillotine
guillotinebreak,break,ititwould
wouldincrease
increase
more
rapidly
(more
than
1atm
=
101.3kPa.)
more rapidly (more than 1atm = 101.3kPa.)

193
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 1

Extremely Confidential

Issue 1: There was no change in radiation dosage in PCV observed by the atmospheremonitoring system between earthquake and Tsunami.
Record ended

Record ended

Time

Time

Radiation Dosage Monitor B in Containment Atmosphere Monitoring System
Radiation Dosage Monitor D in Containment Atmosphere Monitoring System(SV/h)

Radiation Dosage Monitor A in Containment Atmosphere Monitoring System
Radiation Dosage Monitor C in Containment Atmosphere Monitoring System(SV/h)(Red) Radiation Dosage Monitor A in Containment Atmosphere Monitoring System(Green) Radiation Dosage Monitor C in Containment Atmosphere Monitoring System

Reactor No.1: Radiation Dosage Monitor
in Containment Atmosphere Monitoring System(CH-C/A) (1/1)(Red) Radiation Dosage Monitor B in Containment Atmosphere Monitoring System(Green) Radiation Dosage Monitor D in Containment Atmosphere Monitoring System

Same as left (CH-D/B) (1/1)

194Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 1

Extremely Confidential

Issue 1: What kind of damage would workers suffer, if they were exposed to thewater (steam) from the ruptured pipe?

●● IfIf thethepipes
pipeswerewereruptured
rupturedininthe
thereactor
reactorbuilding,building,highly
highlyradioactive
steam
at
70
Atm
and
280
Celsiusradioactive steam at 70 Atm and 280 Celsiuswould
would
eject
from
the
pipe.
eject from the pipe.
●● IfIfworkers
workerswere
weresubjectedsubjectedto
tothe
thesteam
steamdirectly
directlyfrom
fromthetherupture,itishighlypossible
that
they
would
be
killedorberupture, it is highly possible that they would be killed or beseverely
severelyinjured,injured,because
becausethe
thesteam
steamisisextremely
extremelyhot
hotwithwithhighhighpressure
andhighradiation.
pressure and high radiation.
●● The
Thesheer
sheervolume
volumeof
ofsteamsteamejected
ejectedfrom
fromthetherupture
rupturewould
would
fill
fillthethebuilding,building,and
andcausecausethethesurrounding
surroundingarea
areaaroundaroundtherupture
to
turn
foggy
with
zero
visibility
withinthe rupture to turn foggy with zero visibility withinaavery
very
short
periodoftime(orinstantaneously).
short period of time (or instantaneously).

●● InInthe
theaccident
accidentatatFukushima
Fukushima
Dai-ichi
No.1,
there
Dai-ichi No.1, thereareareno
noreports
reportsofoffatal
fatalororsevere
severeinjuries
injuriesfrom
fromsteamsteamatathighhightemperature,pressureortemperature, pressure orradiation
radiationdosage.
dosage.
●● ThereTherearearealsoalsononoreports
reportsoror
alarmsalarmsofofan
anextreme
extremevolume
volumeofofsteam
being
generated,
steam being generated,oror
ononbeing
beingfoggy
foggyandandno
novisibilityintheaffected
visibility in the affectedarea.
area.

●● InIneither
eithercase,case,one
onemustmustcontact
contactstaff
staffoutside
outsidedue
duetotothe
theextremely
extremelydangerous
dangeroussituation.
situation.

195
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 2

Extremely Confidential

Issue 2: The accident in reactor No. 1 progressed much faster than No. 2, 3, and 4
because its primary containment vessel (PCV) is the old model ‘Mark I’. – This hypothesis
was analyzed from the following perspectives.
What
WhatisisMark
Mark1?
1?IsIsititthe
thetypetypeofofthe
thewhole
wholereactor,
reactor,or
orthe
thetypetypeofofPCV?
PCV?
・・

ItItisisthe
thetypetypeofofPCV.
PCV.

IfIfweweassume
assume‘Mark‘Mark1’1’isismore
morevulnerable
vulnerabletotothe
theaccident
accidentlike
likethis
thisthanthanMark
Mark2,2,what
whatwould
wouldbebetheplausibleorrational
reason?
the plausible or rational reason?
・・

ItItisishard
hardtotoconclude
concludethat
thatMark
Mark11isismore
morevulnerable
vulnerablesince
sinceits
itsoutput
outputisisthe
thesamesameororlarger
largerthan
thanthatthatofofMark
Mark2,2,even
eventhoughthoughits
itsspatial
spatialvolume
volumeofofPCV
PCVisissmaller
smallerthan
thanMark
Mark2.2.

・・

The
Themainmainreason
reasonfor
forthetheacceleration
accelerationofofaccidents
accidentsininFukushima
FukushimaDai-ichi
Dai-ichiNo.1
No.1isisthe
thesimultaneous
simultaneousloss
loss
ofofallpowersourcesandtheentirecoolingsystems.
No
rational
data
were
found
to
concludethatthe
all power sources and the entire cooling systems. No rational data were found to conclude that theshapeshapeororvolume
volumedifferences
differencesininPCV
PCVwerewerethethemajor
majorreason
reasonfor
forevent
eventacceleration.
acceleration.

IfIfweweassume
assume‘BWR‘BWR3’3’isismore
morevulnerable
vulnerabletotothe
theaccident
accidentlike
likethis
thisthanthanotherothermodels,models,what
what
would
be
the
plausibleorrational
reason?
would be the plausible or rational reason?
・・

ComparedComparedtotoBWR3,
BWR3,BWR
BWR5’s5’shigh-pressurehigh-pressurepumps
pumpsfor
forECCS*
ECCS*have
havebeen
beenchanged
changedtotomotor
motordriven
drivenwithanemergency
DG
added
as
power
sourceforthepumps.
The
location
of
the
DG
has
been
with an emergency DG added as power source for the pumps. The location of the DG has beenshifted
shiftedfromtheturbinebuilding
to
the
annex
of
reactorbuilding.
(ECCS = emergency core cooling system)from the turbine building to the annex of reactor building. (ECCS = emergency core cooling system)

・・

InInthetheaccident
accidentininFukushima
FukushimaDai-chi,Dai-chi,both
bothAC
ACpower
powerandandthetheDG
DGitself
itselflost
lostfunction
functiondue
duetotoflooding.
flooding.
There
seems
to
be
no
difference
between
BWR
3
and
BWR
5
in
event
progression
in
terms
of
There seems to be no difference between BWR 3 and BWR 5 in event progression in terms ofhighhighpressure
pumps
and
emergency
DG.
pressure pumps and emergency DG.

196

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 2

Extremely Confidential

Issue 2 Mark 1 is a type of PCV*1. There are other plants than 1F*2 reactor No. 1,
which use Mark 1. (*1: primary containment vessel. *2: Fukushima Dai-ichi Nuclear Power plant)
Fukushima Dai-ichi No.1
(Output 460,000kW)［1971］

Fukushima Dai-ichi No.2-5(Output 784,000kW)［1974～1978］

BWR-3
Mark 1(Flask-shaped)

Fukushima Dai-ni No.2-4(Output 1,100,000kW)［1984 - 1994］

BWR-5
Mark 2(Cone-shaped)

BWR-5
Mark 2 Improved(Bell-shaped)

BWR-4
Mark 1(Flask-shaped)
Output （MWe）

BWR-1

BWR-2

BWR-3

BWR-4

BWR-5

BWR-6

160～250350～640460～810540～1100660～1100990～1300

31.2

40.6

41.1

49.7

51.0

54.1

Output Density (kW/l)History of Versions
for BWR Plant

Fukushima Dai-ichi No.6
Fukushima Dai-ni No.1
(Output 1,100,000kW)［1979-1985］

Cycle System
Core Coolant

Double cycle/
Direct cycle
Naturalcirculation/
External forced

Direct cycle
External forced
circulation
7x 7 Fuel

Fuel
Steam-Water
Separation System

Jet pump with single nozzle

Steam drum/
Internal steamwater separator

PCV

8 x 8 FuelInternal steam-water separator

Core spray cooling

ECCS

Low pressure water-feed systems
Suppression chamber（Mark-I)

Dry wellJet pump with 5
nozzlesHigh pressure system enhanced
Suppression
chamber（Mark-II)Suppression
chamber（Mark-III)

Fukushima
Dai-ichiFukushima
Dai-ichiFukushima
Dai-ichiFukushima
Dai-ichiFukushima
Dai-ichiFukushima
Dai-ichiFukushima
Dai-ni

Fukushima
Dai-ni

Fukushima
Dai-ni

Fukushima
Dai-niOnagawa

Onagawa

OnagawaTokai
Dai-ni

Unit 1

Unit 2

Unit 3

Unit 4

Unit 5

Unit 6

Unit 1

Unit 2

Unit 3

Unit 4

Unit 1

Unit 2

Unit 3

Unit 2

Mark 1(BWR-3)

Mark 1(BWR-4)

Mark 1(BWR-4)

Mark 1(BWR-4)

Mark 1(BWR-4)

Mark 2(BWR-5)

Mark 2(BWR-5)

Improved
Mark 2(BWR-5)

Improved
Mark 2(BWR-5)

Improved
Mark 2(BWR-5)

Mark 1(BWR-4)

Improved
Mark 1(BWR-5)

Improved
Mark 1(BWR-5)

Mark 2
197(BWR-5)

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 2

Extremely Confidential

Issue 2: If we assume ‘Mark 1’ is more vulnerable to the accident like this than Mark2, what would be the technical or rational reason?
Possible Hypothesis

Consideration for/against it●● Was
Wasthetheaccident
accidentdevelopment
developmentmuch
muchfasterfasterinin
Reactor
ReactorNo.
No.1,1,because
becausethe
thesizesizeandandvolume
volumeof
of
Mark
1
are
much
smallerthantheothers?
Mark 1 are much smaller than the others?

●● All
AllthethePCV
PCVofofDai-ichi
Dai-ichiReactor
ReactorNo.1-5
No.1-5areareMark
Mark1.1.
There
Thereisisno
nosignificant
significantdifference
differenceininthe
thevolumes
volumesper
perunit
output.
unit output.
●
Though● ThoughECCS
ECCSstructure
structurefor
forBWR
BWR33isisdifferent
differentfrom
from
the
one
for
later
versions,
none
of
the
ECCS
had
the one for later versions, none of the ECCS had
effectively
effectivelyfunctionedfunctionedthis
thistime.
time.

●
● Was
Wasititbecause
becausethe
theMark
Mark11ofofReactor
ReactorNo.1
No.1isisolder
older
and
more
aged
than
the
rest
of
the
reactors?
and more aged than the rest of the reactors?

●● See
Seefollowing
followingpages
pagesforformoremoredetails.
details.
● No.3, which is newer than No.1, also exploded, and No.2, older than No.3
● No.3, which is newer than No.1, also exploded, and No.2, older than No.3
but newer than No.1, did not explode.
but newer than No.1, did not explode.
・ No.1 = activated in March, 1971. No.2 = in July, 1974.
・ No.1 = activated in March, 1971. No.2 = in July, 1974.
No.3 = in March, 1976.
No.3 = in March, 1976.

●● Was
Wasititbecause
becauseMark
Mark11isisthe
theproductproductof
ofananearlier
time
than
the
others,andits
technology
earlier time than the others, and its technology
andandfunctions
functionsare
areinferior
inferiortotothe
thelaterlaterproducts.
products.

●● See
Seefollowing
followingpages
pagesforformoremoredetails.
details.
● Fukushima Dai-ichi No.2-5, and Onagawa No.1 also have equipped Mark● Fukushima Dai-ichi No.2-5, and Onagawa No.1 also have equipped Mark1, but they had followed different event progressions.
1, but they had followed different event progressions.
● It is hard to conclude that all Mark 1s followed the same event● It is hard to conclude that all Mark 1s followed the same event
progressions.
progressions.

The reason why the event progression at reactor 1 was much faster than others is thesimultaneous and complete loss of power and cooling. No rational reason was found
198 tosupport that it was because of Mark 1 (or a type of plant).

Unauthorized copying or distribution of this file is prohibited.
Copyright Team H2O Project all rights reserved

Additional Research: Issue 2

Extremely Confidential

Issue 2: Was the accident development much faster in Reactor No. 1, because
the size and volume of Mark 1 are much smaller than the others? - There is no
significant difference in the volume per unit output with the others.
●● IfIfwewelooklookatatthe
thevolume
volumeper
perunit
unitoutput
outputof
ofPCV,
PCV,Mark
Mark11andandMark
Mark22Improved
Improvedarearethethehighest.
highest. However,
However,its
itsrange
rangeisisamong
among33––4.4
4.4squaresquaremeters.
meters.ItItcan
cannotnotbe
besaidsaidthat
thatMarkMark
11isissignificantly
highinoutputvolume.
significantly high in output volume.
Mark
Mark11(BWR3)(BWR3)Mark
1(BWR4)Mark 1 (BWR4)
Mark
Mark22(BWR5)(BWR5)
Mark
2
Improved
Mark 2 Improved(BWR5)(BWR5)RCCV(ABWR)
RCCV(ABWR)：4.37(㎥/MWt)：4.37(㎥/MWt) (6,030㎥/1,380MWt)(6,030㎥/1,380MWt)：3.11(㎥/MWt)(7,400㎥：3.11 (㎥/MWt) (7,400㎥/2,381MWt)/2,381MWt)：2.97：2.97(㎥/MWt)(㎥/MWt) (9,775㎥(9,775㎥/3,293MWt)/3,293MWt)※※：4.37：4.37(㎥/MWt)(㎥/MWt)(14,406㎥(14,406㎥/3,293MWt)/3,293MWt)※※：3.40：3.40(㎥/MWt)(㎥/MWt)(13,355㎥(13,355㎥/3,926MWt)/3,926MWt)※※(※： See Fukushima Dai-ichi Nuclear Power Plant Accident Investigation Commission Appendix 4 )(※： See Fukushima Dai-ichi Nuclear Power Plant Accident Investigation Commission Appendix 4 )●● IfIfweweexamine
examinethe
theanalyticalanalyticaldata
dataofofaccidents
accidentsmost
mostsimilar
similartotothetheoneoneininFukushima
FukushimaDai-ichi,
Dai-ichi,nonoresults
results
areobserved
tosupport
that
the
time
for
PCV
to
be
severely
damaged(fromthetimingofcore
damage)are observed to support that the time for PCV to be severely damaged (from the timing of core damage)isismuchmuchshorter
shorterfor
forMark
Mark11than
thanthetheotherothertypes.
types.

199
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 2

Extremely Confidential

Issue 2: Was it because the Mark 1 of Reactor No.1 is older and more aged than therest of the reactors? – No data was gained to conclude aging as a major reason forfaster event progression.
●● The
Theassessment
assessmentofofaging
agingdegradation
degradationhas
hasbeenbeenconductedconductedfor
forplants
plantsactivatedactivatedoverover3030years,
years,based
basedononthehistoryof
theiroperationandrepairs.
the history of their operation and repairs.
－－ After
After30
30years
yearsofofoperation,
operation,periodic
periodicreassessment
reassessmenthas
hasbeenbeenmandated
mandatedininlesslessthanthanevery
every1010years.
years.
th●yearofof● The
Thesecondsecondassessment
assessmentwas
wasconductedconductedlast
lastyear
yearatatFukushima
FukushimaDai-ichi
Dai-ichiReactor
ReactorNo.1
No.1(at(atthethe39
39thyearits
itsoperation).
operation).

●● IfIfthe
thereactor
reactorisisassumed
assumedtotooperate
operateforfor60
60years,
years,ititisisassessed
assessedthat
thatmost
mostofofthe
theequipments
equipmentsandandbuildings
wouldbemaintained
in
a
good
condition
inthefuture,bykeeping
current
maintenancebuildings would be maintained in a good condition in the future, by keeping current maintenanceactivities.
activities.
●● For
Forsomesomeofofthethekeykeyequipments
equipmentsand
andbuildingbuildingstructures,
structures,ititwas
wasassessed
assessedthat
thatthey
theywould
wouldbebemaintained
maintained
ininaagood
conditionbythemaintenanceactivitieswith16
maintenance
items
in
25
categories
good condition by the maintenance activities with 16 maintenance items in 25 categoriesnewly
newly
added.
added.

Based on the accident in Dai-ichi No.1, the assessment should be conducted in RPV,
structures of the reactor such as shroud, and piping systems within RPV such as therecirculation piping. However, no significant differences are observed in No.1 compared200
to the others.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 2

Extremely Confidential

Issue 2: (Continued) Procedure of Aging Degradation Assessment
Assessment Procedure● Classify major safety equipments and building● Classify major safety equipments and building
structures into 16 Categories
structures into 16 Categories
・ Containment (RPV, PCV), pump, heat exchanger, pump motor,
・ Containment (RPV, PCV), pump, heat exchanger, pump motor,
pipe, valve, structures in reactor, cable, concrete and steal
pipe, valve, structures in reactor, cable, concrete and steal
construction, measurement control system, power source system,
construction, measurement control system, power source system,
etc.
etc.

Eg.) Strength
degradation by
neutronembrittlementin RPVEg.) Irradiation
assisted stresscorrosioncracking(IASCC) in therecirculation
piping systems● Extract aging degradation events● Extract aging degradation events・ Equipment materials, environment of use, past accidents, etc.
・ Equipment materials, environment of use, past accidents, etc.
● Examples of major aging degradation events● Examples of major aging degradation events
・ Strength degradation of RPV body in neutron-irradiated・ Strength degradation of RPV body in neutron-irradiatedenvironment (neutron embrittlement)
environment (neutron embrittlement)・ Stress Corrosion Cracking (SCC) of stainless-steal equipment
・ Stress Corrosion Cracking (SCC) of stainless-steal equipment
under high temperature and purified water environment such as
under high temperature and purified water environment such ascore shroud , recirculation piping systems etc.
core shroud , recirculation piping systems etc.
・ Material loss of inside of pipes by corrosion
・ Material loss of inside of pipes by corrosion
・ Degradation of insulating equipments such as cables by heat,・ Degradation of insulating equipments such as cables by heat,
irradiation etc.
irradiation etc.
・ Strength degradation of concrete structures by heat, irradiation,
・ Strength degradation of concrete structures by heat, irradiation,
etc.
etc.
● Perspectives for aging degradation assessment● Perspectives for aging degradation assessment
・ Aging degradation effect to equipments
・ Aging degradation effect to equipments
・ Effect against seismic strength・ Effect against seismic strength・ Appropriateness of current maintenance activities to the trends of・ Appropriateness of current maintenance activities to the trends ofoccurrence and progression of aging degradation eventsoccurrence and progression of aging degradation events・ Extraction of additional maintenance needs to current activities.
・ Extraction of additional maintenance needs to current activities.
● Define long-term maintenance policy● Define long-term maintenance policy
・ Action plan for next 10 years. (long-term maintenance201
policy)・ Action plan for next 10 years. (long-term maintenance policy)
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 2

Extremely Confidential

Issue 2: (Continued) Time comparison by the Type of PCV (From Core Damage to
PCV Damage) (by Analysis)

BWR-3
Mark I

BWR-4
Mark I

BWR-5
Mark II

BWR-5
Mark II (Improved)

RCCV
ABWR

Long-term loss of powersource (TB)

4.5

10

4.5

4.5

11

Loss of power source during
the small rupture of pipe &loss-of-coolant accident(LOCA) (S2B)

17

16

12

12

9

Failure in high/low pressure
coolant injection (TQUV)

18

13.5

7.5

9.5

33

Failure in high pressure
coolant injection and depressurization (TQUX)

16

10

7

7

24.5

Failure in coolant injection
during LOCA (AE)

10.5

9

3.5

4

16

Minimum Hours

Level 2 PSA Analysis in Earthquake (BWR ) in 2009, data from Japan Nuclear Energy Safety Organization in October 2010.

202
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 3

Extremely Confidential

Issue 3: Otherwise, the emergency cooling function (Isolation Condenser: IC) should havefunctioned and the accident development should have been much slower. – Thishypothesis was analyzed from the following perspectives.
How
HowlonglongwaswasICICdesigned
designedto
tomaintain
maintainits
itscooling
coolingfunction?
function?
・・
ItItisisdesignedtomaintainitscoolingfunctionforapproximately
designed to maintain its cooling function for approximately88hours
hourswithout
withoutany
anywaterwatersupply
supplyininthe
thecondenser.
condenser.
Had
HadthetheICICbeen
beenfunctioning
functioningafter
afterthetheearthquake,
earthquake,and
andTsunami?
Tsunami?Why?
Why?
・・
・・
・・
・・

The
TheIC
ICwas
wasactivatedactivatedautomaticallyautomaticallyby
bythe
thescram
scramafter
afterearthquake,
earthquake,and
andhadhadbeen
beenfunctioning
functioningnormallynormallyuntil
untilthetheTsunami.
Tsunami.
The
operators
openedandclosedtheexternalvalve(DCdriven)ofIC
threetimes,
followingtheoperatingprocedure
The operators opened and closed the external valve (DC driven) of IC three times, following the operating proceduretotokeep
keep
itsitscooling
rate
at
55
Celsius/hr.
cooling rate at 55 Celsius/hr.
Asboth
As boththe
theDC
DCand
andAC
ACpower
powersources
sourceswere
werelost
lostsimultaneously
simultaneouslydue
duetotoTsunami,
Tsunami,thetheinternalinternalvalves
valvesofofIC,
IC,whichwhichwaswasdesigned
to
close
in
case
of
AC
power
outage(i.e.
‘fail-close’),wasmostlyclosedandtheexternal
valves(DCdriven)designed to close in case of AC power outage (i.e. ‘fail-close’), was mostly closed and the external valves (DC driven)ofofIC
IC
also
lost
its
open/closefunction.
also lost its open/close function.
As
Asaaresult,result,ititisisassumed
assumedthat
thatthetheIC
ICcoolingcoolingsystemsystemwas
waslostlostafter
afterthetheTsunami.
Tsunami.

How
Howlong
longdid
didthetheICICcool
coolthethecore,core,according
accordingto
tothe
therecords?
records?
・・
The
Therecords
recordsofofthe
thewaterwaterlevels
levelsininthe
theemergency
emergencycondensers
condensersindicate
indicatethat
thatapprox.
approx.15%
15%ofofthe
thewaterwaterhad
hadbeenbeenevaporated
evaporatedininsystem-A,
system-A,and
andalmostalmostno
nowaterwaterhad
hadbeenbeenevaporated
evaporatedininsystem-B.
system-B.
・・
Deducedfromtheamountofthere
evaporation,ICcooling
Deduced from the amount of there evaporation, IC coolinghad
hadfunctionedfunctionedfor
foronly
onlyabout
about4545minutes
minutesfrom
fromthetheearthquake.
earthquake.
Did
DidICICstop
stopdueduetotoinappropriate
inappropriatemanual
manualoperations,operations,ororwas
wasititinevitable?
inevitable?
・・
・・
・・

Operators
Operatorsrecognizedrecognizedaapossibility
possibilityofofDC
DCrecovery
recoveryatat18:18
18:18on
onMarchMarch11,
11,andandopened
openedthe
theexternal
externalvalve
valveandandclosed
closedititatat
18:25.
18:25. Then,
Then,thetheoperators
operatorsopened
openedthe
thevalve
valveagain
againatat21:30,
21:30,and
andhadhadkept
keptititopened
openedfrom
fromthen.
then.
However,as
IC’s
internal
valveshad
been“mostlyclosed”
aftertheTsunami,these
open/close
However, as IC’s internal valves had been “mostly closed” after the Tsunami, these open/closeoperations
operationsofofthe
theexternal
external
valves
does
not
seem
to
have
had
significant
effectsonthefunctionalityofIC.
valves does not seem to have had significant effects on the functionality of IC.
Therefore,
Therefore,manual
manualoperations
operationswould
wouldnotnothavehavemademadeaasignificant
significantdifference
differenceininthe
theaccident
accidentdevelopment
developmenteven
eventhoughthoughthethedirector
directorororoperators
operatorshad
hadcorrectly
correctlymanipulated
manipulatedthe
theexternal
externalvalve
valvebetween
between18:25
18:25toto21:30,
21:30,since
sincethetheinternalinternalvalves
valveshadhadremainedremained“mostly“mostlyclosed”,
closed”,meaning
meaningthe
theIC
ICwas
wasclosed
closedinternallyinternallyno
nomattermatterwhat
whatthethesituation
situationofofitsitsexternal
externalvalves
valveswas.
was. 203
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 3

Extremely Confidential

Issue 3: How long was the IC designed to maintain its cooling function?
Data from GE: extracted from Design and Analysis Report● It is designed to maintain thecooling system for approximately 8hours without any water-feed in thecondenser.
“An eight hour supply of water isstored above the isolation condenser
tubes”

Construction Permit Application of
Fukushima Dai-ichi Reactor No.1
(See the next page)● In actual operation, 80% of thecondenser tank is filled with water
but not 100%. With this water, theIC can work for approximately 8hours.
204
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 3

Extremely Confidential

Issue 3: (Continued) Construction Permit Application of Fukushima Dai-ichi
Reactor No.1 (Extracted)

Effective Water Volume in Tank

106m3

With two water tanks, IC can cool down the reactor
core for 8 hours without any water supply.

205
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 3

Extremely Confidential

Issue 3: Had the IC been functioning after the earthquake, and before Tsunami?
=> It had functioned normally.
IC Operations after earthquake and before
TsunamiPressure of reactor No. 1

●

●

①
②
③
④
⑤
*
Reactor Pressure

Open/close status of IC valves (Investigated on April 1, 2011)
System-A* Valve-1A： Opened partially* Valve-2A： Closed ⇒ Opened (opened at 18:18)* Valve-3A： Closed ⇔ Opened(opened at 18:18 /closed at 18:25/opened at 21:30)* Valve-4A： Opened partially

System-B* 1B： Opened partially* 2B： Closed* 3B： Closed* 4B： Opened partially

The IC was activated automatically by the scram
after earthquake, and had been functioning
normally before Tsunami hit.
The operators opened and closed the externalvalve (DC driven) of IC three times, following theoperating procedure to keep its cooling rate at 55
Celsius/hr.
14：46 Scrammed by earthquake
Core pressure increased by closure of main steam isolationvalve
14：52 IC automatically activated, and the core pressure
decreased.
15：03 (approx.) Valves-3A & 3B closed.
15：10~15：30 (approx.) Adjustment of core pressure by
open-close operations of valve-3A.
15：37 Loss of all AC power by Tsunami(Since then, all recording had ceased due to complete powerloss)

IC Operations after Tsunami
18：18 Activated (Valves-2A & 3A opened)
18：25 Deactivated (Valve-3A closed)
21：30 Activated (Valve-3A opened)
March 12, 1：48 Problems in fire pump system for cooling206
water supply were found.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 3

Extremely Confidential

Issue 3: How had the tsunami and complete loss of AC/DC power affected ICfunctions? => As its internal valves (AC driven) were designed to close in case of power
loss (= fail-close), these valves were closed and its cooling function was lost.
Sequence of IC Function after Tsunami (Presumption)
Open Air

Open Air

Emergency Isolation
Condenser (IC)DC
From Purified
Water feed
SystemReactor Pressure
VesselAC

From Fire
Extinguishing
System・DC power was lost due to ground fault after tsunami.
=> A signal to close all valves was sent due to power loss of logic
circuit (driven by DC).

・

DC driven valves (valves-2&3) were activated and closed before DC
was lost. (Valve 3: kept closed. Valve 2: opened => closed)
AC driven valves (valves-1&4) were also activated then closed before
power loss.

DC

・

AC
ReactorCoolant
Recirculation
SystemPump

・Then, the possibility of recovery from ground fault was recognized
only for DC.
- Valves-2A&3A were opened manually. Then, 3A was closed
manually.
- Again, valve-3A was opened around 21:30, and kept opened sincethen. Staff on site believed it functioning.

・

According to later verification, the records indicated the internal valves(1,4) as partially opened. (In actuality, mostly closed.)・The make-up water line also lost its functions due to all AC powerloss.

Primary Containment Vessel

Power Source for IC Valve
・ External Valves (Drive for 2A/B, 3A/B, Control Circuit)： DC
・ Internal Valves (Drive for 1A/B, 4A/B, Control Circuit)： AC・ Logic Circuit：DC=> Send signals to close valve in time of pipe rupture, power loss, etc.
・ Make-up water line (Control, drive, logic circuit )： AC

This had accelerated the accident progression in reactor No.1 much faster than No.
207
2, 3, and 4.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 3

Extremely Confidential

Issue 3: How long was the assumed IC cooling time, according to the records? =>Deduced from the reduction in water level, the IC had cooled for only about 45 minutes.
Based on these water reduction, it is assumed that the IC
had functioned for only about 45 minutes after the scram.

IC water level indicator shows 65% in system-A
and 83% in system-B.
●

IC is designed to cool for a total of 8 hours.
－ 4 hours for each system-A&B. (Total 8 hours )●On daily operation, they maintained the water level around 80%.
－ Thus, water level is 80% if nothing happens.

●

As shown on the left, about 15% of water has been reduced insystem-A, and almost none reduced in system-B. This means thatit had cooled about 45 minutes.
－ 4 Hours (240 minutes)×15%÷80% ＝ 45 minutes●

Observing the water reduction and heat exchange, only system-Aof IC had cooled for about 45 minutes after the earthquake,
before tsunami, and thereafter.*－ System-B： Valve-3B was closed right after IC activation by the scram inaccordance with operation manual. With valve-3B closed, Tsunami hit andvalves-1B&4B were also closed due to AC loss. Therefore, IC system-B
had hardly cooled.

１００％
８０％
６０％

Pressure/Water Level
MeasurePressure/Water Level
Measure* Actual timing of evaporation of cooling water depends upon the effectiveness ofheat exchange (= boiling and evaporating) under different conditions. Further
investigation is necessary.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved－

System-A： IC had functioned by open/close operation of valve-3A after
earthquake before Tsunami. As AC power lost by tsunami, valves-1A&4A
were mostly closed. After that, it had not functioned much at all.

－After Tsunami, system-A had activated for 7 minutes from 18:18. Valve3A was indicated as opened from 21:30. However, it is assumed
that valves
208
1A & 4A were mostly closed at that time.

Additional Research: Issue 4

Extremely Confidential

Issue 4: What could have been done to reactor No.1 in order to avoid the hydrogen
explosion and leakage of radioactive materials? – This issue was examined from thefollowing perspective.
What
Whathadhadsignificantly
significantlyaccelerated
acceleratedthe
theevent
eventprogression
progressionininreactor
reactorNo.
No.1?
1?
●
●
●
●
●
●
●
●

Loss
Lossofofparametersparametersininthe
thecentral
centralcontrol
controlroom
roomdueduetotocomplete
completeloss
lossofofall
allAC/DC
AC/DCpower
powerbybythe
theearthquake
earthquake
andtsunami.
and tsunami.
Loss
Lossofofall
allthethehigh
highpressurepressurecooling
coolingfunctions
functions(IC,(IC,HPCI).
HPCI).Disability
Disabilitytotomaintain
maintainthe
thewaterwaterlevel
levelofofthe
thecore
core
under
high
pressure.
under high pressure.
IfIfthat
thatfunction
functionhad
hadbeenbeenmaintained,
maintained,there
therewaswasaapossibility
possibilitytotobring
bringininemergency
emergencypower
powersource
sourceandandequipments
to
keep
the
core
stable.
equipments to keep the core stable.
Simultaneous
Simultaneousaccidents
accidentsininreactors
reactorsNo.
No.1-41-4mademadethetheaccident
accidentmanagement
managementevenevenharderharderand
andworsened
worsenedthe
thesituation.
situation.

What
Whatwould
wouldhave
havebeen
beeneffective
effectiveto
toavoid
avoidthetheevent
eventprogression?
progression?
●●●●

SecureSecuremultiplicity
multiplicityand
anddiversity
diversityofofpower
powersources
sourcesand
andcooling
coolingsystems
systemsunder
underanyanysevere
severecircumstances.
circumstances.
Practical
trainings
toensureeffective
andprompt
use
of
the
above
(e.g.
set
up
alternative
power
Practical trainings to ensure effective and prompt use of the above (e.g. set up alternative powerwithin
withinXX
hours).
hours).

What
Whatactions
actionsshould
shouldhave
havebeen
beentaken
takentotoavoid
avoidthetheexplosion
explosionand
andradioactive
radioactiveleakage?
leakage?
●●

See
Seethethefollowing
followingpages
pagesforformoremorespecificspecificdetails.
details.

209
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Additional Research: Issue 4

Issue 4: What had significantly accelerated the event progression in reactor No. 1 are
the following.
3/11 14:46

Emergency
shutdown of thereactor

EventsEarthquake occurred (level 6+)

Progression of accident (conceptual)(M9.0. 4th in recorded history)

Earthquake occurs● 14：46 Automatic shutdown of the reactor => 14：52 IC activatedautomatically & opened/ closed manually.
● Loss of all external power => 14：47 Emergency DG activated.
15:35
Tsunami hit(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

External event
Countermeasures taken
Problem occurred orprogressed

Loss of all external
power (AC)(Tsunami-M9.1. 4th in recorded history)(Immersion height: 11.5~ 15.5m)
Loss ofall power&
importantfunctions

Automatic activation of
emergency DG● Emergency DG & power panels flooded => all AC power lost => Unable
to use electrical equipments.
● Battery room submerged => DC power lost => Electrical boards,
measuring & control facilities lost => Cooling function lost (IC, HPCI),
Pressure control function lost (open SRV remotely etc.)● Seawater pump lost => Function for cold-shutdown lost (ultimate heatsink lost)

Right after tsunami: Isolation Condenser lost=> Core water level started to drop.

Secureemergency
power.

Core cooling by IC
Tsunami hit
Loss of all power(AC, DC, emergency DG)

17：12 Plant manager ordered to consider water injection by fire pump system & fire truck

Prepare forcoolant
injection.

18：46 Core damage started (estimated)

21：19 Core water level became readable (TAF + 200mm*0)
23：00 Rise in radiation level in turbine bldg confirmed.
Around then, 1st power supply vehicle arrived.
3/12 00：06 Plant manager ordered to prepare vent.
(as Dry-well of PCV pressure possibly over 600k Pa)
01：30 Requested to execute vent & approved by the country.

Prepare forventilation

02：30 Confirmed ‘RPV pressure is low & PCV pressure is high’*1.
05：46 Started to inject fresh water by fire trucks.
07：20 RPV damaged. (simulation)
Tried water
injection.
Triedventilation.
Hydrogenbuilt up.

Hydrogen
Explosion &radiation leak

09：04 Workers departed for site for ventilation.
10：17 Started PCV vent.
14：30 PCV vent succeeded (D/W pressure decreased)

Loss of water injection
Loss of ventilation

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

Release gas from PCV(Manual vent)Core damage starts
with massive FP & H2

H2 leaks into

14：53 Completed freshwater injection (80,000 l in total).
14：54 Plant manager ordered sea water injection.

reactor bldg from PCV

Water injection and coolingby fire truck, etc.

Reactor building exploded (5th floor)

Hydrogen explosion
at reactor bldg

Fission products 210
released

15:36

19：04 Started sea water injection.
20:45 Started sea water injection with boric acid.

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Fukushima Dai-ichi Unit 1… Deduced Problems…

Problems deduced from the events: Simultaneous loss of all power and cooling & vent functions had
disabled the recovery operations, and taken the ‘cool and shut-down the core’ function away.
Progression of accident (conceptual)
Earthquake occurs(M9.0. 4th largest in recorded history)

Emergency shutdownof reactor (scram)

Loss of all external
power (AC)Automatic activation of
emergency DGCore cooling by IC
Tsunami hit
Loss of all power(AC, DC, emergency DG)
Loss of water injection
Loss of ventilation

Temperature andpressure in PCV rise

Water level goes down.
Fuel rods start exposed.

Release gas from PCV(Manual vent)Core damage starts
with massive FP & H2

reactor bldg from PCV

H2 leaks into

Water injection and coolingby fire truck, etc.

Hydrogen explosion
at reactor bldg

Fission products
released

Problems

Countermeasure● Secure power
AC power was lost over the long-term due to earthquake and tsunami.
AC power was lost over the long-term due to earthquake and tsunami.
supply vehicle,● As Unit 2 also lost power, the power could not be shared with Unit 1.
● As Unit 2 also lost power, the power could not be shared with Unit 1.
power panel,● Due to submergence, there was no electrical panel to be connected with the power supply vehicle.
● Due to submergence, there was no electrical panel to be connected with the power supply vehicle.
parameter● Due to extremely bad environment, even after the power supply vehicles arrived, reaching power● Due to extremely bad environment, even after the power supply vehicles arrived, reaching powermonitoring
connection port, and connection itself was difficult.
connection port, and connection itself was difficult.
AM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for
AM hadn’t assumed the simultaneous loss of all AC/DC power (=DC won’t be lost for
long-term).
long-term).
● As IC is DC driven, along with DC loss, MSIV was closed (unable to access to internal valves● As IC is DC driven, along with DC loss, MSIV was closed (unable to access to internal valves
for vent).
for vent).
● Due to all power loss, they could not remotely open the valves for ventilation.
● Due to all power loss, they could not remotely open the valves for ventilation.
● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure● There was no specific AM procedure defined for SBO with simultaneous loss of DC (procedure
handbook for SBO only assumed that DC power was normal).
handbook for SBO only assumed that DC power was normal).

● Secure back-up
battery● Diversify DC
power source● Improve
operability ofventilation

Securing alternative cooling water source was insufficient and delayed.
Securing alternative cooling water source was insufficient and delayed.
● Due to power loss, core depressurization was delayed (battery depletion, insufficient pressure of air● compressor).
Due to power loss, core depressurization was delayed (battery depletion, insufficient pressure of aircompressor).
● Lack of easy depressurization method under DC loss. Not prepared for working under high● Lack of easy depressurization method under DC loss. Not prepared for working under highradiation (alternative method other than SRV necessary?).
radiation (alternative method other than SRV necessary?).
● There was a malfunction in diesel-driven fire extinguishing pump.
● There was a malfunction in diesel-driven fire extinguishing pump.
● Liquefaction & debris caused extreme difficulty in accessing & constructing external water● Liquefaction & debris caused extreme difficulty in accessing & constructing external water
injection line.
injection line.
● Insufficient injection ability of external water pump.
● Insufficient injection ability of external water pump.
● Securing and supplying alternative water source was prolonged.
● Securing and supplying alternative water source was prolonged.
PCV vent function was lost. Manual ventilation was delayed.
PCV vent function was lost. Manual ventilation was delayed.
● Lack of easy depressurization method under DC loss. Not prepared for working under high● Lack of easy depressurization method under DC loss. Not prepared for working under highradiation.
radiation.
● Other than W/W vent, there was no operation procedure or device to prevent fission products● Other than W/W vent, there was no operation procedure or device to prevent fission products
from leaking outside, when conducting dry-well vent or other direct ventilation.
from leaking outside, when conducting dry-well vent or other direct ventilation.

● Station fire truck,
portable pump,heavy machinery● Diversify &multiplex water
source & route● Enhance highpressure water
injection● Review location& operability ofvent valve● Store cylinder
for valve

Lack of precaution, monitoring, and actions against building explosion (hydrogen● Ventilation forLack of precaution, monitoring, and actions against building explosion (hydrogen
explosion).
reactor
explosion).
● No preparation for building ventilation in case of long-term AC power loss.
building● No preparation for building ventilation in case of long-term AC power loss.
● No mechanism to detect hydrogen generation.
● Hydrogen● No mechanism to detect hydrogen generation.
● No method to release accumulated hydrogen outside of the reactor building.
detector● No method to release accumulated hydrogen outside of the reactor building.
Emergency facilities at sea side were so vulnerable that they could not do almost
Emergency facilities at sea side were so vulnerable that they could not do almost● Practicalanything after the loss of ultimate heat sink.
anything after the loss of ultimate heat sink.
training● Though overall AM procedure of ‘high pressure cooling => core depressurization => water● Though overall AM procedure of ‘high pressure cooling => core depressurization => water
Review AM
injection by low pressure cooling => PCV depressurization” was defined, specific AM/operational ● 211
injection by low pressure cooling => PCV depressurization” was defined, specific AM/operational
manualprocedures in case of simultaneous loss of all power & vent functions were not clearly defined.
procedures in case of simultaneous loss of all power & vent functions were not clearly defined.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Additional Research: Issue 4

Issue 4: Couldn’t the accident development in reactor No.1 have been prevented or
mitigated if the following countermeasures were possible?
Assumed Event Progression

Core damage starts
with massive FP & H2

H2 leaks into
reactor bldg from PCV

Water injection and coolingby fire truck, etc.

Hydrogen explosion
at reactor bldg

Fission products
released1

Preparation

Transport extra power supply vehicles, power panels,
pumps, fuel etc by air as needed (w/inhrs).

Release gas from PCV(Manual vent)24●

Water level goes down.
Fuel rods start exposed.

Prepare LPCI tocold shutdown( hrs – wk)

Temperature andpressure in PCV rise

24

Transport equipments for low pressure cooling while maintaining highpressure cooling. Secure sufficient power supply. Clear access routes● Maintain high pressure cooling (HPCI/RCIC) to buy more time.
● Clear & secure access routes for heavy machineries.
● Transport and secure sufficient power source & DG for 3-7 days.
● Maintain core pressure with SR valve & activate S/C cooling to buy more time.
● Bring in & prepare equipments for low pressure cooling system.

8

Additional supplies and supports for heavymachineries etc. (Secure access).

Loss of water injection
Loss of ventilation

Keep highpressure cooling(Withinhours)

Core cooling by IC

8

Recover & maintain high pressure cooling to buy more time. Secure
more power source (for second use)
● Transport and connect batteries (Recovery of DC).
● Activate high pressure cooling systems (IC or HPCI).
● Prevent core damage by high pressure cooling till off-site support arrives.
● Transport & connect power supply vehicles (DC/AC) for more power supply.
● Secure additional water & fuel (at least for 24 hours).
● Continuously monitor hydrogen detector.

(Off-site)●

Loss of all power(AC, DC, emergency DG)

Recover HPCI
(W/in hrs)

Tsunami hits

Secure power (for initial use), functions of control room & IC. Prepare forhydrogen explosion● Switch to emergency batteries (small, portable, can bring in & connect w/in 2 hr).
● Secure parameter monitoring system in central control room (by battery).
● Establish system to overview the availability of all the power source.
● Open reactor-building vent (to prevent hydrogen explosion) before water level
reaches at TAF.
● Redesign internal valves (AC driven) of IC to Fail-Open.
● Bring in equipments and devices to repair high pressure cooling systems.

●

Automatic activation of
emergency DG

2

AM actions (On-site)

Transport back-up DG/batteries, power panels etc
by air. (Have to be compact and highly portable,
w/in
hrs by IC runs out.)

Loss of all external
power (AC)empl

Initial Action(W/in hrs)

Emergency shutdownof reactor (scram)

Assumes the event progresses till here.

Earthquake occurs(M9.0. 4th largest in recorded history)

Exa

24

Reduce core pressure & prepare for low pressure cooling system● Set up lines & systems for low pressure cooling. Prepare for alternative water
injection (alternative sea water pump, CS pump etc.)● Prepare to de-pressurize the core with SR valve.
Reduce core pressure. Activate low pressure cooling systems for cold
shutdown● Reduce core pressure. Activate low pressure cooling systems.
● Achieve cold shutdown.

● Diversify emergency DG/DC● Set storage for severe AM at onsite upland● Daily trainings.
(principle, location, height etc).
(power sources, power panels, pumps, fuel etc.)(Quantified efficiency test)● Prepare protective clothing, masks, ● Enforce water protection (breakwater, water stops● Secure communication methods.
dosimeters etc.
for building, watertight doors etc.)● Enhance seismic-durability, diversity, and● Diversify water source and path.
flexibility of external power.
● Install hydrogen detector.

212

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Issue 4

Extremely Confidential

Issue 4: In addition, couldn’t the following accident management have been
worth considering to reactors No. 2, 3, and 4?
1 Prevent event progression in No.1
by procedures in previous page.

CommonEvents
3/11

Earthquake (14:46)
Tsunami hit (15:35)

Damage to working environment● Darkness (No lighting)● No monitoring data (loss of measurement and control function)● Fire trucks: 1 out of 3 = damaged by Tsunami (15:37),1 = isolated at
Damage to plant
No.5&6 and unable to transport (15:37)
Plant response after earthquake● Loss of all external power (14:46)● No communication means, difficult to instruct and direct (bwn central● Emergency shut down (Scram succeeded)● Loss of entire Emergency DG (15:37)
control room & fields)● Activated emergency generator (DG)
● DC batteries flooded (~15:41)● Difficult to transport people & materials (liquefaction & rubble)● Activated high pressure cooling● Loss of seawater cooling system● Horribly severe working environment (frequent aftershocks, highradiation)
Severe damage to plant and site
● Limited activity & working hours (lack of protective suits, masks &(simultaneously to No.1 – 4)
dosimeters)
Tried to connect a power supply vehicle toNo.2 (P/C was active) to secure power.

Tried to recover reactor No.1 at first.

Fukushima Dai-ichi No.1
・ Tried to reduce core pressure.
・ Couldn’t monitor water level
reaching to TAF. Couldn’t feedwater. Water level went down・ Core boiled w/ no water in it

3/12● Loss of entire power● Loss of seawater cooling● IC was functioning?
● Assigned 1 fire truck

Core damage
started(approx. 18:46)

Dai-ichi No.2

Cooling by RCIC(14:50)

Tried to keep RCIC in No.3 (battery
was active) to buy more time.

● Loss of entire power● Loss of seawater cooling● Regular/emergency P/Cavailable● RCIC available● Assigned 1 power supply
vehicleDai-ichi No.3

Hydrogen Explosion (15:36)
3/13● Loss of entire AC power● Loss of seawater cooling● DC battery available● RCIC available● HPCI available

4. Maintain RCIC in No.2, byconnecting power supply
vehicle from offsite to P/C(which was active).

RCIC stopped (11:36)
Power supply vehicle
damaged (approx.15:36)

Cooling by HPCI(12:35)

Trying to connect
the vehicle to P/C torecover AC.
Vehicle destroyed
by explosion.

Was preparing water
injection by fire truck asbattery for RCIC was
running out.
17:17 Water level = TAF (estimated).
Around 18:00 Started to reduce core pressure.
Core boiled with no water in it.

3/15

Dai-ichi No.4

Cooling by RCIC(15:05)

HPCI stopped (2:42. DC depleted)Core damage started

4:15 Water level = TAF.
Core boiled with no water in it.

(approx.8:46)

Massive generation& accumulation of hydrogen
3/14

3. Bring in equipments &set up core depressurization and low● Loss of entire power pressure cooling● Loss of seawatercooling systemsystems in the mean
● Regular/ emergency
P/C available
time.

Put lower priority on No.4 as it wasunder regular inspection & on halt.

Massive generation& accumulation of hydrogen・ Water injection by fire
truck (x 80. 5:46~14:53)

9:08 Rapid depressurization of the core
9:25 Started water injection by fire truck(Pure water with boric acid)

Fire truck damaged (apx.11:01)

Hydrogenaccumulation(back flow from No.3
since its core damage?)

Hydrogen Explosion (11:01)
RCIC stopped (approx.13:25)
Core Damage Started(approx. 19:46)
Massive generation& accumulation of hydrogen

After RCIC stopped, tried& failed vent (both W/W& D/W) as R/D didn’t
rupture (= high designed
pressure).

Hydrogen discharged from blowout panel?
(PCV damaged?) S/C pressure = 0 MPa(abs)

2. Maintain RCIC by recharging battery (only one
survived) from power
supply vehicle on site (orones from offsite) to No.3 .

Hydrogen Explosion (6：12)

5. Bring in equipments & set
up core de-pressurizationand low pressure coolingsystems in the mean time.
6. If they could prevent coredamage & hydrogen
explosion at No.3,
hydrogen back-flow to No.4,
and its explosion could be
avoided.
213

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research… Issue 4… Local Earthquake

Extremely Confidential

If a local earthquake occurs and the pipes between reactor building and turbine
building are ruptured, what safety measures would be effective?
Presumed Accident Development

Large & local
earthquake happens
Reactor scram.
Main steam piping
ruptured.

● What if it is impossible to close themain steam isolation (MSI) valve?
・ Pipe between reactor building and turbine
building is ruptured.

Rupture detected &main steam isolation
valve closed

・ The main steam isolation valve will be closed due toincrease of main steam flow volume, high radiation
dosage, lowering pressure, etc.
･ Reactor water level will increase due to growth of voidand steam will flow out in two layers until the isolation
valve is closed.

Water level inreactor goes down.
Signal sent for
automatic shut down.

・ The reactor water level will not reach to TAF.
・ Core pressure will be maintained at high level.
・ As the main steam isolation valve is closed (more than10%), a signal for automatic shut-down will be sent to
the reactor.

PCIS activated(due to low water level).

・ Approximately 60 valves in PCIS (primarycontainment isolation system) will be closed.

Cooling by IC.

・ If IC is not automatically activated, it will be done
manually.

Cooling by shut-down
cooling mode.

・ Core pressure will be reduced, and low pressure
cooling will be maintained.

Cold shut down

⇒ Bring in the equipments (valve jig, powersource, nitrogen cylinder, etc.) and close the
MSI valves manually.

● What if MSI valves malfunction andentire AC power is lost due to Tsunami orother accident?
⇒ ・ Close external valves of MSI valve system toavoid leaking.
・ Secure power source and ultimate heat sink to
avoid decrease in water level and core exposure.
・ Prepare gas-turbine generator, power supply
vehicle, alternative cooling system, etc.
・ Maintain monitoring and water injection to
the core.
・ Eliminate rubble by frontend loader, etc.
● It is also important to enhance the major
access roads to the site in terms ofseismic strength.

214
As for the accident like this, our proposal, multiplicity and diversity of power and ultimate
heat sink, would be effective.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research:

Extremely Confidential

Other
OtherQuestions
Questions

Q. 1:

Why was the radiation level increased around March 20, 2011?
Is it because the ventilation was operated in Fukushima Dai-ichi reactor No.2?

Q. 2:

Could seawater injection to Dai-ichi No.1 have been operated much earlier?
Was there any delay in decision making?

Q. 3:

Was the hydrogen explosion in Dai-ichi No.4 caused by hydrogen back-flow from No.3?

215
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Questions

Extremely Confidential

Question – 1: Why was the radiation level increased around March 20, 2011?
Is it because of the ventilation operated in reactor No.2?
=> No ventilation was operated in individual plants. It is estimated that radiation
dosage was affected by direction and velocity of the wind.
●

Radiation Dosage ： On March 15 and 16, approximately 12000μSv/hr were recorded temporarily in front of the main gate of
Fukushima Dai-ichi. Other peaks were; approx. 5000μSv/h on March 18, approx. 4000μSv/h on March 19, and approx.
3400μSv/h on March 20 (all in front of the main office building). Since then, the radiation dosage decreased.

●

Wind Direction： Fission products could be floated towards Niigata area, by winds from: the northeast, east-northeast, east, eastsoutheast and southeast. Record histories of wind from northeast to southeast around March 20 around Fukushima Dai-ichi wereas follows:- March 18- March 19- March 20- March 21●

12:20~16:40
3:30~10:30
5:40~14:30
5:10~ 6:50
11:40~18:30( 4 hours 20 mins)( 7 hours )(10 hours 10 mins)( 1 hours 40 mins)( 6 hours 40 mins)

Maximum radiation dosage level: approx.

4400μSv/h, wind velocity: 2.0 m/s
700μSv/h,
1.5 m/s
3000μSv/h,
1.9 m/s
2300μSv/h,
0.7 m/s
2100μSv/h,
1.5 m/s

Not only a wind with a high radiation dosage had blown longest from the east on March 20, but also strong wind (maximum
6.8m/s) with a high dosage had blown from the east on March 21. The causes of high radiation dosage around March 20 and 21
could be the wind direction and velocity during these days.
- According to the Asahi Shimbun on August 11, wind direction was toward the south on 3/20 A.M., southeast on 3/20 P.M.,
and northeast on 3/21~22.

●

Isn’t it because of the vent operation in Dai-ichi No.2?
- No vent operation had been conducted since March 15.

●

Examination on the parameters in Dai-ichi No.2
- Since 6:00 AM on 3/15, pressure in Suppression Chamber (S/C) were immeasurable and the dry-well pressure was lowered toatmospheric pressure. Based on this data, PCV could have been damaged. Then, it is most likely that the vent system would216
notfunction even if it had been performed.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Additional Research: Questions(Cont.) No Ventilation for PCV was operated in Dai-ichi No.1, 2, and 3 on March 20, 2011.
Radiation dosage levels, and wind direction/velocity in Fukushima Dai-ichi (March 20, 2011)
West gate
11:25 No.3 W/W Vent

Increase of Dosage

Around Main Gate
Main Gate(S/C Vent Valve (AO valve) Large Valve opened)Wind Velocity

When wind blew from Southeast orSouth, the dosage increased.

Weather

DIANA Assessment

Sunny
Cloud

Radiation Dosage Rate

Rain
18:20 Steam from No.2 R/B

Administration
Building North

Administration
Building NorthWest Gate
No.1 DW PressureNo.2 DW PressureNo.3 DW Pressure
Time & Date

● After 2:30pm on 3/20, radiation dosage in north ofadministration building had increased.

North

South

Wind Direction

West

Around Main Gate
Main Gate

Southeast to
south

East

Time & Date

Administration
Building NorthWest Gate● It is assumed that this increase was due to winds
blowing toward southeast to south. (from thehearing with TEPCO).
● In Dai-ichi No.1,2, and 3, no PCV ventilation was
operated on March 20, 2011. (from the hearing
with TEPCO).
217
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Questions

Extremely Confidential

Question - 2 : Could seawater injection to Dai-ichi No.1 have been operated much earlier?
Was there any delay in decision making?
=> It could be done around the time of the explosion. However, the explosion retarded somuch that it was delayed 4 hours after instruction.
March 12 5:46 Plain water injection started with fire truck from Fire
Protection system line.
Two fire trucks arrived in the morning(from Kashiwazaki Kariwa Nuclear Power Plants, Self-Defense Force)

March 12 around 12:00 Started to prepare for sea water injection(permitted by CEO of TEPCO)
March 12 14:53 Plain water injection ended

March 12 14:54 Seawater injection was ordered.

March 12 15:36 Explosion of Reactor No.1

● Started preparation of seawater injection around 12:00● By 15:30, the injection line was almost set up. They
used reverse-valve pit of No. 3 as water source(seawater carried by Tsunami) and connected three fire
trucks in order to secure lift height. The set up was
almost finished.
● Due to the explosion in No.1 around 15:36, some staff
were injured. Even though the plant manager ordered toconfirm fire protection pump for water injection, staff
were also busy confirming safety and radiation dosage
within the plants. They started checking fire trucks andbuildings around 17:20.

March 12 19:04 Started seawater injection into core by fire trucks.

● Around 18:30, report on field situation began. With
scattered rubble with high radiation dosage, and thedamage of hoses for the injection lines, they found thatthey could not use them.

March 12 20:05 Seawater injection ordered by Article 64 in Regulations● The staff gathered hoses in hydrants around the area,connected them, and reconstructed the injection line.
They started the seawater injection around 19:04.

Some injured. Operation suspended. Order of evacuation. Safety
confirmation. Radiation dosage increase. Situation confirmation.
Damage of hoses for injection line. Reconstruction of the line.

218
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Questions

Extremely Confidential

Question – 3: Was the hydrogen explosion in Dai-ichi No.4 caused by hydrogen backflow from No.3?
Consideration from Additional Research

VentilationhydrogenininNo.
No.33still
stillflow
flowbackback
Ventilationpipes
pipesof
ofNo.
No.33had
hadruptured
rupturedby
bythe
theexplosion,
explosion,would
wouldhydrogen
to
No.
4?
to No. 4?
●● From
Fromphotos
photosofofreactors
reactorsNo.
No.33&&4,4,SGTS
SGTSpipelines
pipelinesininbothbothreactors
reactorshad
hadnotnotruptured.
ruptured.(See(Seeotherothersheet)sheet)
IfIfwewecalculate
calculatethe
theamountamountof
ofhydrogen,hydrogen,which
whichwere
weregenerated
generatedand
anddetonateddetonatedininNo.3,
No.3,andandshifted
shiftedto
to
No.
4,
could
the
explosioninNo.
4
explosion
occur?
No. 4, could the explosion in No. 4 explosion occur?
●● TEPCOTEPCOcalculated
calculatedthat
thatthetheamountamountofofhydrogenhydrogengenerated
generatedininNo.
No.33fromfromthethetimetimeofofmeltdown
meltdowntotoexplosion
explosionwas
was
about
about600-700
600-700kg.
kg.
●
floor
● ThisThisamountamountneeds
needstotobe
besufficientsufficienttotodestroy
destroythethefloor44&&55ofofNo.
No.3,3,and
andfloor
floor44&&55ofofNo.
No.4.4.=>=>12%12%ofof ththhydrogenhydrogenlevel
leveldestroys
destroys400
400mm
mmconcrete
concreteon
on44thfloor.
floor.4%
4%ofofhydrogenhydrogenlevel
leveldestroys
destroys250
250mm
mmconcrete
concreteon
on55thfloor.
floor.
●
600-700kg
ofofhydrogen
could
accumulate
ininthe
level
above
(more
than
12%
on
44ththFl.,● Theoretically,
Theoretically,
600-700kghydrogen
could
accumulate
the
level
above
(more
than
12%
on
Fl.,and
and4%
4%on
on
th
55thFl.).
However,
approximately
more
than
13%
of
hydrogenlevel
isnecessaryfordetonation.
FurtherverificationFl.). However, approximately more than 13% of hydrogen level is necessary for detonation. Further verification
isisnecessary.
necessary.
TEPCO Announcement

Supporting
SupportingData
DataofofHydrogen
HydrogenininReactor
ReactorNo.3
No.3shifted
shiftedto
toNo.4No.4●● Because
Becausethe
theradiation
radiationdosage
dosageatatthe
theexitexitside
sideofofSGTS
SGTSfilter
filtertrain
trainininNo.
No.44isishigher
higherthan
thanatatthe
theentrance
entranceside,
side,they
they
assumethathydrogenhadshifted
from
No.
3
to
No.
4.
assume that hydrogen had shifted from No. 3 to No. 4.
●● According
Accordingtotothe
thephotographs
photographsofofwater
waterlevel
levelininthe
thespent
spentfuelfuelpool
poolininNo.
No.4,4,and
anddatadataononnuclear
nuclearspecies
speciesidentified
identified
ininthepool,
they
assumed
the
very
low
possibility
that
a
large
volumeofhydrogenwere
generatedinthethe pool, they assumed the very low possibility that a large volume of hydrogen were generated in thepool.
pool. 219
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Additional Research: Questions

Extremely Confidential(Reference) Unit 3 & 4 SGTS exhaust duct

↑Unit 4 SGTS exhaust duct
interconnect

Exhaust stack →↓Unit 3

220

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Additional Research: Questions(Reference) Unit 3 & 4 SGTS exhaust duct
Dai-ichi No.3: After Explosion
East Face

West Face

South Face

North Face

221
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR
PWR

222
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Project Formation: PWR

Extremely Confidential

The project formation on the PWR are the following:Those who cooperated with interviews, hearings and data-gathering:

Kenichi
KenichiOhmae
Ohmae

KansaiKansaiElectricElectricPower
Company
Power Company● Kansai Electric Power Co., Inc. Manager, Nuclear AccidentManagement and Nuclear Power Div., Mr. Kensuke Yoshihara● Kansai Electric Power Co., Inc. Project Manager, Plant &Maintenance Engineering Group, Nuclear Power Div.,Mr. Toshihiko Tanaka● Kansai Electric Power Co., Inc. Tokyo Office
Manager, Mr. Toshikazu Sendo
Assistant Manger, Mr. Takahiro Ohgami

Head
HeadOffice
Office● Ohmae and Associates, Inc.
Partner, Mr. Iwao Shibata● Japan Nuclear Fuel Ltd.
General Manager,
Reprocessing Planning Dept.,
Reprocessing Business Div.,Mr. Manabu Yusa

Mitsubishi
Mitsubishi
Heavy
HeavyIndustries
Industries● Mitsubishi Heavy Industries, Ltd. Acting Manager,
Advanced Plant Safety Dept., Nuclear Energy Systems Div.,Mr. Daisaku Okuno

223
Unauthorized copy or diversion of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Purposes of this Research on PWR (Pressurized Water Reactor)●● To
Toshow
showGeneral
GeneralFeatures
FeaturesandandDifferences
Differencesbetween
betweenBoiling
BoilingWater
WaterReactors
Reactors (BWR)
(BWR)
and
andPressurized
PressurizedWater
WaterReactors
Reactors (PWR)(PWR)●● Whether
Whetherlessons-learned
lessons-learnedfrom
fromAnalyses
Analyseson
onFukushima
FukushimaDai-ichi
Dai-ichiand
andDai-ni
Dai-niNuclear
NuclearAccidents
Accidentsare
areapplicableapplicableto
toPWR
PWRor
ornot
not
●
● Specific
SpecificConsiderations
ConsiderationsNecessary
Necessaryonly
onlyfor
forPWR
PWRininorder
ordertotoprevent
preventreoccurrence
reoccurrenceofof
accidents
accidents●● To
ToshowshowififDiversity
Diversityand
andMultiplicity
Multiplicityofofsafety
safetymeasures
measuresinstructed
instructedcurrently
currentlyby
bythe
the
Nuclear
Nuclearand
andIndustrial
IndustrialSafety
SafetyAgency
Agency(NISA)(NISA)ininthe
theMinistry
MinistryofofEconomy,
Economy,Trade,
Trade,andandIndustry
Industryare
aresufficient.
sufficient.

The following pages discuss the above points.

224
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

FeaturesFeaturesofofBWR
BWRandandPWR:
PWR:
Are
AreLessons-Learned
Lessons-Learnedfrom
fromBWR
BWRapplicableapplicableto
to
PWR?
PWR?

225
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Differences Between BWR and PWR: Despite several functional differences, they must
control water and pressure level after the scram to use high-pressure cooling, reduce corepressure, and use low-pressure cooling for cold shutdown.
External Power ● Both BWR and PWR have the same power receiving system via the switching
BWR
station, in which there are no differences.

Reactor Containment

Steam

AC Power ●Reactor Containment
Steam

Water
Control
Rods●

Generator
Transformer

TurbineTurbine Generator

Fuel

DC Power ●

Water
Water
Water

Recirculation
Pump

Pressure
Control
Pool●
Condensate System
Discharge Channel
Coolant (Sea Water)

Water
Reactor Containment

Circulation Pump

PWR

Pressurizer

Steam Generator

Control Rods●

Cooling System ●(High Pressure)

Reactor Feed Water Pump

●

Steam

Water

TurbineGenerator

●

Water

Condensate System

Cooling System ●(Low Pressure) ●Discharge Channel

Reactor Containment

Coolant (Sea Water)

Water
Coolant
Pump

Fuel

Circulation Pump
Reactor Feed Water Pump●

No differences in the systems for the Diesel Generators (DG) for
Emergencies, and the AC Power Source.
Location of emergency DGs and AC Power Panels are different in each plant.
Usually, power sources for BWR are installed below ground level, andthose for PWR are at ground level.
In both BWR and PWR, the setup of DC Power, converting from andcharged by AC power source, is same.
In case of Extreme Emergency, BWR is designed to maintain approximately
eight hours of power source for the High Pressure Coolant Injection System,
Control System, and Supervisory Devices.
PWR is designed to maintain approximately five hours of power source forplant and Supervisory Devices.
With high pressure in the reactor pressure vessel, BWR maintains its normal
water level via IC, RCIC, HPCI, HPCS and so on while the SR Valvecontrols the pressure in the core.
In PWR, the water level of the Steam Generator (SG) is maintained byelectrical/turbine-driven auxiliary feed-water pump, and the plant
cools down and lowers pressure by emitting radioactivity-free steam
through the Main Steam Relief Valve.
One difference from BWR, PWR can release steam to the air, and the TurbineDriven Auxiliary Feed-Water Pump can maintain its functions even after DC
batteries are drained.
Water pump in ECCS (RHR, etc.) operates for coolant injection.
In BWR, after pressure in the vessel is released by the SR valve,water is injected to the reactor for cooling and shutting down.
In PWR, after injection of highly concentrated boric acid, either
water supply and drainage, or residual heat removal pump will be
operated for cooling and shutting down.

226
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR(Cont.) In PWR, radioactive coolant circulates only within containment vessel, therefore
only uncontaminated coolant water (and steam) is released to the outside ocean and air.
Pressure
Reduction

BWR

Back up Power
Branch Point
Power System for
Emergency

Electric Line●

Reactor Building

Main SteamEmergency Line (High)Ventilation Valve

Cooling System
during Reactor
Isolation

Reactor Pressure Vessel

Reactor Containment

Spent Fuel Pool

Emergency Line (Low)

●

Spent
Fuel

Containment Main Steam
Pipe
Ventilation Line

Condensate
Storage Tank

Fuel
Fuel Pool
Coolant Pump

To Cooling
System during
Reactor
Isolation

Air Stack

From Condensate
Storage Tank

Suppression

Reactor Auxiliary Sea Water
Pump

Ultimate
Heat Sink(Release valve)

Emergency DG

Ventilation
Function

Chamber
Fire Pump
RHR

Pipe Connecting Port

Reactor Auxiliary Coolant Pump

Ocean

●

PWR

●
●

●

●

Filtered Water Tank

Condensate Transport
Pump

Electric Line
Reactor Containment

Back-up Transformer
Transformer

Water Tank for FuelExchange

CentralControl
Room

Steam Generator
ControlRod

DG for Emergency

Reactor Auxiliary
Coolant Pump

Drinkable Water

Electric Driven Power
Condensate Tank

Spent Fuel Pit Pump Spent Fuel Pit

●
●

Steam

Secondary Purified Water Tank

Turbine Driven Power
Spent Fuel Pit
Coolant●

Condensate Water

Reactor Recirculation Sump
Reactor Recirculation Sump
Isolation Valve

Reactor Auxiliary
Cooling Water
Coolant System●

Condensate System

Primary Coolant Pump
Pressurizer Safety ValveRHR Pump●

TurbinePressure
Accumulating
Tank
Reactor Containment
Monitoring Plant
Parameter

Intake Pit

Reactor Spray

Spray Pump

Generator

Prevention of
Hydrogen
Explosion

Main Steam
Ventilation Valve

Main Transformer

BWR reduces pressure in the core by transferring steam in
the pressure vessel to the suppression chamber (S/C, S/P) in
the containment vessel.
PWR reduces pressure by releasing steam (without radioactive
materials) which has exchanged heat in the Steam Generator(SG) through the Main Steam Relief Valve to the open air.
Main Steam Relief Valve in PWR is located outside of the containment
vessel and can be opened both mechanically and by hand.
For both BWR and PWR, the ocean is the ultimate heat sink so
the pumps are located at ocean-side.
Further, PWR can release heat to the open air as another ultimate
heat sink.
BWR contains vent lines from S/C and D/W as vent forcontainment vessel. Rupture disks are set in these lines so as to open
when the pressure reaches its set level.
The volume of the containment vessel in PWR is roughly fivetimes (*) greater than the BWR, and vent lines are notinstalled for decreasing pressure. (*: Compared with a BWR with thesame output)
BWR prevents hydrogen detonation by encapsulating
nitrogen into the containment vessel.
In the Fukushima Dai-ichi, it is presumed that hydrogen explosion
occurred due to hydrogen leaks from containment vessel throughvarious penetrations and pipelines into the reactor building. This
leakage was not assumed.
PWR prevents hydrogen detonation by having a larger
containment vessel. For plants with smaller vessel, the hydrogen
igniters are set in order to lower hydrogen level.
Though PWR does not assume hydrogen leakage to the containment
annulus, it has the annulus filter units if leakage occurs.
There is a research which reports the amount of zirconium, thegeneration source of hydrogen, in PWR is less than half that utilized in
BWR.
227

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

One study in U.S. reported that the amount of zirconium in the PWR is less than half ofthat in the BWR, since PWR does not have a channel box for the fuel rods like BWR does.

Reference: In-Vessel Zircaloy Oxidation/Hydrogen Generation Behavior During Severe Accidents
Prepared by A.W. Cronenberg September 1990. NUREG/CR-5597

The report indicates that the hydrogen level in PWR is much less than that for BWR,
because the absolute quantity of hydrogen in PWR would be much less, and the228
containment vessel in PWR is five times larger than BWR.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Are Lessons-Learned from the analyses of BWR in Fukushima applicable to PWR?
=> Yes, it is applicable and the importance of “Supplying enough power and cooling
function under any severe circumstances” is the same for PWR.
Summary of Lessons-Learned from the Research on BWR, and its Applicability to PWR*
Category

Lessons-Learned(Approx.)Applicable to
PWR?

Comments

Earthquake and Tsunami

20

O- All Applicable

Loss of Power Source

31

O- All Applicable

Loss of Sea Water Cooling
System6

O- All ApplicableComparison with other plants

7O- All Applicable

High Pressure Cooling System

22

O- All Applicable- PWR does not require external power for the cooling system using aturbine-driven auxiliary feed-water pump.

Ventilation

29

O- All Applicable for Main Steam Relief Valve.
- Not Applicable in regards to the rupture disk and ventilation of PCV
since PWR doesn’t have equivalent devices.

Low Pressure
Cooling System

10O- All Applicable

Overall25

O- Not Applicable for ventilation since PWR doesn’t have an
equivalent rupture disk or ventilation of containment vessel.
- Except for the above, most categories are Applicable.

229* See appendices for more details.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

SpecificSpecificconsiderations
considerations
necessarynecessaryfor
forPWR
PWR

230
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Is there any specific point to be considered for PWR, in order to prevent theaccidents like the one in Fukushima Dai-ichi?
●
PacificOcean
OceanEarthquake
Earthquakeon
onMarchMarch11,11,● During
Duringthethehistory
historyofoflarge
largeearthquakes
earthquakesininJapan
Japanincluding
includingthe
theTohoku
Tohoku- -Pacific
all
BWRs
in
Japan
have
succeededinperforming
scram
of
the
nuclearreactorfollowing
theearthquakes.
Can
all BWRs in Japan have succeeded in performing scram of the nuclear reactor following the earthquakes. Can
PWR
PWRscram
scramreact
reactininthe
thesamesameway
wayduring
duringearthquakes
earthquakesof
ofthe
thesamesamelevel?
level? (Refer(Refertotothe
thefollowing
following
pages.)
pages.)●● InInthe
theevent
eventofofloss
lossofofall
allAC
ACpower,
power,isisititpossible
possiblefor
forthetheprimaryprimaryreactor
reactorcoolant
coolanttotoleak
leakfrom
fromthethepumppumpseals,
seals,
which
whichmay
maycausecausethethemajor
majorloss
lossofofcoolant,
coolant,andandleadleadtotothe
thenonfunctioning
nonfunctioningof
ofthe
thehigh
highpressurepressure
coolingcoolingsystemsystemininthe
thecore?
core? (Refer(Refertotothe
thefollowing
followingpages.)
pages.)●● PWR
PWRisisdesigned
designedtotoprevent
preventthe
theriseriseofofpressurepressureinincontainment
containmentvessel
vesseland
andhydrogenhydrogendetonation
detonationby
byusingusingaalarger
largercontainment
containmentvessel,
vessel,and
andby
byreleasing
releasingmost
mostofofthe
theheatheatininthe
thecorecorethroughthroughthe
themainmainsteamsteamrelief
reliefvalve
valvetotothe
theopen
open
air.
air.TheThecontainment
containmentvessel
vesselofofPWR
PWRisisfive
fivetimes
timeslarger
largerthan
thanthatthatofofBWR
BWRwith
withthethesamesameoutput.
output.Therefore,
Therefore,
PWR
PWRdo
donot
nothave
haveventilation
ventilationsystems
systemsto
tolowerlowerthethepressurepressureininthe
thevessel.
vessel.Also,
Also,they
theydodonot
notrequirerequirepressurepressurereduction
reductionof
ofthe
thecorecoreduring
duringthetheoperation
operationfor
forcold-shutdown.
cold-shutdown.
●● InInPWR,
PWR,spent
spentfuelfuelpits
pitsareareplacedplacedoutside
outsideofofthe
thecontainment
containmentvessel
vesseland
andatatthe
thegroundgroundlevel.
level.Compared
Comparedto
to
that
in
BWR,
it
is
more
accessible
fromoutsideofthebuilding.
(For
bothaccessandlevel.)
that in BWR, it is more accessible from outside of the building. (For both access and level.)●● ThereTherearearetwotwoultimate
ultimateheat
heatsinks
sinksininPWR,
PWR,thetheoceanoceanandandopenopenair.
air.
231
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Insertion of Control Rods – The top 20 cm of the control rods are inserted into the fuelrods at all times. These rods will react with earthquake motion of 160 gal (1/5 of thedesigned value) and will drop into the fuel rods within 2 seconds by gravity.
● The securement of pathway is important for control rod insertion.
=> The pathway is secured as the chart below, and has been verified in tests.
1. Guide by Guide Tube/
Board

Insertion Pathway
Control Rod Cluster

Control Rod Drive

Middle Guide Board forControl Rod Cluster Guide
Tube

-

-

Insertion pathway is supported by various guide boards andtubes.
Fuel assembly is supported by upper and lower core boards
to avoid sideslip or uplift. (BWR has no support for verticalmovement.)
During the reactor trip*, the control rod cluster will drop by
gravity. (In BWR rods will be inserted from the bottom.)*： An example of the designed value of the core trip in earthquake =160Gal (The settings differ from plant to plant.)

Control
Rod

Control Rod Cluster Guide Tube

Upper Core
Guide(a) Reactor Core

2. The top part of control
rod clusters are always
inserted in fuel assembly.
3. Guide by guidethimble for control rods

Upper Nozzle

4.Top and bottom part offuel assembly is supported
by guide pins. 232

Fuel Assembly(Control Rod Guide
Thimble)(b) Insertion Pathway ofControl Rod Cluster

Control Rod Cluster

Upper Core Support
Board

Fuel Rods (Control
Rod Guide Thimble)

Insertion
Direction

Insertion
Direction

Control Rod Cluster Guide
Tube(Control Rod Cluster inside)

Upper Guide Board forControl Rod Cluster
Guide Tube(c) Insertion Guide
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR(Cont.) On the insertion during earthquake, the vibration test with real size* verified
that control rods are inserted even with simulated seismic wave 3.3 times of thedesigned value. (It will be activated at 1/5 of the designed value. )Overview of the Test

<Direction of Vibration>
制御棒駆動装置

Control Rod Drive

Fuel Assembly

支持架台

10 m

Support Trestle

Baffle Board

タイロッド

Tie-Rod

10 M

Simulation
Test

Container for the test

Control Rod Drive

Control Rod Guide Tube
制 御 棒 クラスタ案 内 管

Control Rod Cluster
Guide Plate
Gap
冷却材

冷却材

Coolant

Baffle Board

Coolant＜Result＞<Condition of Vibration>= Number of Fuel Assembly(b) Arrangement of Fuel Assembly

Fuel Assembly(x3) 燃 料 集 合 体
Fuel Assembly

試験容器

Test Containment
1.5 M
1.5
m

Time

Approx.約3 3mM

Vibration
振動台
Table

Gap

(a) Overview ofVibration Test

・ Simulation of the seismic wave: The test was designed so that the vibration
at fuel assembly and control rods becomes the severest by modeling realplant. (S2 Envelope Wave)
・ Maximum acceleration of simulated seismic wave is 950 Gal.
・ The test verified whether the control rods are inserted with the simulated
seismic wave up to 3.3 times of the designed value.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Input Acceleration(c) Correlation between insertion time of control rods and input acceleration

Control rod cluster is inserted along with guide tube
during the simulated seismic wave (3.3 times as large
233asS2) without any damage.
(*2005 JNES Report「Equipment Endurance 2 “PWR Simulation Test of Control Rod Insertability”)

Extremely Confidential

PWR

Reduction of Primary Coolant: There is a possibility that if SBO happens the core cooling
does not properly function because water injection to the primary coolant pump does notwork and the coolant starts leaking through the sealing of the pump.
Containment Vessel

RCP Seal Unit (Enlarged)

Pressurizer

Reactor Vessel

To Coolant Drain Tank
Steam Generator
Water

No.3 Sealing Leak Off
TurbineGenerator

The 3rd Seal
No.2 Sealing Leak Off
No.1 Sealing Leak Off(Return of Injected Sealing Water)

To Water Discharge Path

Primary Coolant
Pump

The 2nd Seal

To Volume Control Tank

Cooling Water (Sea Water)

The 1st Seal

Primary Coolant Pump (Enlarged)

RCP Seal

OutsideFrom Volume Control Tank

×

VolumeControl
Tank

M

CCW Pump(Auxiliary Reactor Coolant Pump)
M

At SBO,① Sealing Water Injected

Containment
InsideAt SBO,M
Shut Down
At SBO,×

Returning Line for
Injected Sealing Water×

Manual Shut Down

RCS water (hot)reaches the RCP
sealing unit due to lossof external power .
Thermal Barrier Coolant System

At SBO
Manual Close×

At SBO
Shut Down

M

Injection Line for Sealing Water
Rupture Disk

Pressurerizer Release Tank

×

Filling Pump

Sealing Water Injection System

Flow Channel②① Normally： High-pressured sealing water is injected fromthe volume control tank and circulates along the blue path.
This prevents primary coolant from leaking from the core.
② At Loss of All AC Power: Because the circulation ofsealing water in the blue path stops, the primary coolant
234
in the core could possibly leak through the red path.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR(Cont.) If the core is cooled down to the hot-stable state*2 by TDAFWP*1 , and even if the
primary coolant leaks from RCP seal, almost same amount of water will be injected fromthe accumulator tank. The core will remain stable. (*1 Turbine-Driven Auxiliary Feedwater Pump. *2 approx. 170℃、0.7MPa)
Assumptions For Analysis• 4 Loop Plant

Primary
Condition• Output of power generation, core-pressure, average temperature of the
primary coolant are the most probable value.

Disturbance・ External power loss at 0 seconds, turbine trip, loss of primary water
injection, and coast-down of RCP.
・ The reactor is tripped by the signal of low RCP revolutions.

Back-up Water
Injection

・ Back-up water injection starts after one minute (To 4SG)・ The volume of back-up water injection is adjusted so as to maintain thewater level in SG.

Operation by
operator• Starts compulsory cool down by opening all the MSR valves after 30
minutes.

Accumulator
Tank

・ Injects boric acid solution to RCS as the pressure in the core drops.
・ Close the exit valve of accumulator tank when RCS pressure drops to
1.7MPa [gage].

Decay Heat

・ FP: Recommended value from the Atomic Energy Society of Japan・ Actinide: ORIGEN2

Leak Volume

・ Leaks from RCP

Assumptions of Event Progress
T

Event Progress and Operation－

・SBO occurs
・Start leaking from RCP

Time

0 sec

Comments
Initial leak rate from RCP is
21gpm/RCP

1.5 sec－

Activate turbine-driven
auxiliary feed water pump

1min

－

3

Start opening MSR valve

30 min4

Activate accumulator tankapprox. 1 hr

RCS pressure: 4.2MPa[gauge]

5

Manually close the exit valveof accumulator tankapprox. 12 hrs

RCS pressure: 1.7MPa[gauge]

6

Manually open/close MSR
valve

approx. 12 hrs

Cool down RCS aiming at 170℃

7

Stop leakage from RCP

approx. 14 hrs

RCS pressure 0.83MPa[gauge]

approx. 19 hrs

RCS pressure 0.7MPa[gauge](RCS = 170℃)

1

Reactor Trip

2

8

Achieve stable-cooling status

Cool down RCS aiming at 208℃

100x10Chart A： Volume of Primary Coolant Leakage
3 from RCP Seal
7

● In complete loss of all
the AC power, theprimary coolant leaks
through the sealing of
RCP (Chart A)

80
60
40
20
0
0

10

20

30

40

50

60x10

3

Time (sec)

100x10

時間 (秒)
Chart B: Volume of Automatic Water Injection
from Accumulator Tank with Primary Coolant
Leakage
3

60
40● Then, about the sameamount of coolingwater will be injected
into the coreautomatically fromthe accumulator tank .
(Chart B)● As a result, cooling
function of the core
would be maintained
without major
reduction of primarycoolant.

580
Accumulator Tank (kg)

Target Plant

VolumeR CLeakage
Pか ら の漏 え from
い 量RCP（ (kg)
kg）

Condition

Injection
蓄Volume
圧 タ ンof クAutomatic
か ら の Water
注 入 量
積 算 値from
（ kg）

Item

4

20
0
0

10

20

30

40

Time
(sec)
時間 (秒)

50

60x10

3

235

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Current
CurrentSituation
Situationof
ofPWR:PWR:
Case
CaseStudy
StudyofofOoi
OoiNuclear
NuclearPowerPowerPlant
Plant
Reactors
ReactorsNo.3
No.3andandNo.4
No.4

236
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

Position and Altitude of Major Equipments: Main buildings are constructed at 9.7m
altitude. Batteries and major power panels (M/C, P/C) are at 15.8m, the emergency
generators are at +10m, and sea water pumps are at +4.65m.

Reactor Containment Vessel
Spent Fuel Pit
Main Steam Relief Valve
Steam Generator
Battery Room (DC Panel)
Central Control RoomTransformer (+13.5m)
Steam Turbine
Fuel for Fire Pump (+14.4m)(+26.0m)(+21.8m)(Ground Level +9.7m)(+15.8m)(+18.1m)

Sea Water Pump(+10.0m)

Accumulator Tank(+17.1m)(Motor Lower End: +4.65m)(+3.5m)Reactor Containment
Charging Pump (+10.0m)

EL (Altitude)： 0m
DG for Emergency
Turbine Driven Auxiliary Feed Water Pump
Auxiliary Air Compressor

Residual Heat
Removal Pump

<Cooling Water Supply Destination>
・Residual Heat Removal Pump
・High Pressure Core Injection Pump
Auxiliary Cooling Water Pump (+7.0m)
・Charging Pump
・Spent Fuel Pit Pump
Electric Driven Auxiliary Feed Water Pump
・Auxiliary Air Compressor, etc(+3.5m)237
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

Core Cooling System: PWR has two ways to release heat, the open air and ocean as ultimate
heat sinks. Both can lead to low-heat shutdown without releasing radioactive materials.
● Release the heat (cooling water)
exchanged in ECCS (Residual Heat Removal
System) to the ocean.
● The water released to the ocean isfrom the third order system anddoes not contain radioactive
materials.

To Fire Extinguisher
System

Plain
Water
Tank
Ｍ

Boracic Acid
Tank

● Release the heat (steam) by exchanging
heat in steam generator to open Air● The steam released to the air issecondary and does not containradioactive materials.
Reactor Containment

Electric Fire
Extinguisher Pump

Reactor Container Spray System

Diesel Fire Extinguisher
Water Pump

External PowerAir Cooled Type
Emergency
Generator System

Ｍ

Ｍ

Ｍ

Steam
DrivenStarting
Valve
Main Feed
Water

Accumulator
Pressurizer
Tank
Control
Reactor Container Spray System
Rods

Steam
Generator

High Pressure
Injection System

Main Feed
Water Isolation
Valve

Ｍ

Residual Heat
Removal System

Ｍ

Metal-Clad
Switchgear

Ultimate Heat Sink
海へ
＝ OceanSteam Turbine

Main Steam Line
Drain

Turbine Driven
Auxiliary Feed
Water Pump

Reactor Containment

Primary Coolant
Pump

Ｍ

Generator for
Emergency

Isolation Valve

Pressurizer
Ventilation Valve

Charging
Pump
Ｍ

Secondary Purified
Water Tank

Ｍ

Fuel
Exchange
Water Pit

Boracic Acid
Pump

Ultimate Heat Sink
＝ Open Air
Main Steam

Main Steam
Relief Valve
Main Steam

Auxiliary Cooling
Water Pump

Condensate
Pit

Electric Auxiliary Feed
Water Pump

Fire
Pump

Large Pump

Reactor Containment
Vessel Sump
Ｍ

Sea
Water

238

Sea Water Pump
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

Cooling Procedure at SBO (Station Blackout): There are 2 steps: High Heat Shutdown (to 0.7MPa、170℃), and Low Heat Shutdown (to 93℃). Both ultimate heat sinks, ocean and open air,are available for the latter.
Core Cooling System 1 (High Heat Shut Down)

Conduct either one of below after
preparation to low-heat shutdown① Turbine driven auxiliary feedwater pump is activatedautomatically.

15.4MPa

Core Cooling System 2 (Low Heat Shut Down)

Pressure of Primary Coolant② Open main steam relief valve, and activate
core cooling system via steam generator(operated manually)

During 1 to 4, no power
necessary except for
the very moment of theactivation of 1.

Method 1: (Heat Sink to Open Air = Feed & Bleed
Method)● Inject boric acid to primary cooling system in thecore by boric acid pump. (0.5 MPa, down to Approx.
159℃)● Feed sea water to steam generator directly by firepump.
● Simultaneously, drain sea water, injected from drainline in main steam line, to lead to low-heat shutdown.
(Approx. 93℃)

③ Boric acid is automaticallyinjected from the accumulator
tank at approx. 4.2 MPa.
④ Stop cooling at approx. 1.7 MPa, and close
exit electric valve at accumulator tank (toprevent mixture of nitrogen into primarycooling system)

4.2MPaMethod 2: (Heat Sink to Ocean)● Activate core auxiliary cooling system, after setting
up the sea-water supply line from the large pump toauxiliary water cooler.
● Inject boric acid to primary coolant system bycharging pump.
● Operate residual heat removal system to low-heat
shut down (to Approx. 93℃).

⑤ Restart cooling after closing exit electric
valve of accumulator tank.
⑥ Stop cooling at approx. 0.7 MPa of

1.7MPa(Approx.208℃)

primary cooling, and continue
removing heat constantly(Approx. 170℃)

0.7MPaTo Low Heat Shut Down
0.5 day
Loss of All
AC Power

Approx.
1day

Time

In PWR, the core is stably controlled at approx. 170℃. Cooling shutdown below 100℃
239
has less technical significance as is in BWR.

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

Overview of Safety Measures: Since March 11, 2011, they have been strengthening themultiplicity and diversity of safety measures in three areas, security of power, coolant,
and countermeasures against flooding. (As of November, 2011)
Releasing in the Open Air

Reactor Containment

3.3.Countermeasure
CountermeasureagainstagainstFlood
Flood● Sealing of doors

Pressurizer

Release steam without
radioactive materials tothe open air

Steam

Reactor Containment
Steam Generator
Water

Central Control Room

TurbineGenerator

Battery

SecureMonitoring
System
燃料● Set air-cooling emergency
generator etc.

3.3.Countermeasure
CountermeasureagainstagainstFlood
Flood● Sealing of doors

Each major system will be explainedin the following pages.

Ｐ

Rotate by Steam

1.1.Securement
SecurementofofPower
SourcePower Source

To Water Discharge Path

Circulating Cooling Water (Sea Water )Water Pump
Water Feed Pump

Turbine Driven Auxiliary
Feed Water Pump

Feed water by steamdriven pump (notelectricity)

Condensate
Tank

Plain
Water
Tank

2.2.Securement
Securementofof
Water
SourceWater Source● Feed Water by Fire Pump 240
etc.

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

1. Securement of Power Source: To strengthen multiplicity and diversity, large air-coolingemergency generators are set at 33.3m. Trainings enabled onsite staff to start feeding
power to entire reactors within 78 minutes after SBO.
Hardware： Multiplexing and Diversification of Power Sources

In order to secure necessary power source for all reactors No.1 - 4(Diversify cooling methods)
More Diversified
Total：2310kVA
14600kVA
Systems
Power Supply toMore Core(Mid to long term plan)
Monitoring Devices
Cooling Methods
・Central Control
Room・Boric Acid Pump
・Residual Heat
Removal System etc.

・Emergency Core
Cooling System
・Sea Water Pump etc.

Software： Training Enforcement
In order to connect power supply vehicles and emergency DGs
as quick as possible● Establish
organizations● Prepare manuals
and operate training
・Set up power supply vehicles.
・Connect power cables.
・Drive power supply vehicles.
・Fuel to power supply vehicles.

Connecting with power
supply vehicles

Power Supply Vehicle* All numbers are per plant

●
・

・
●
・

Air Cooling Emergency
Generator: 8 units

Measures for quick and secureconnections
Connection port and cables are
installed right next to the DG toavoid unnecessary transportation
Located in altitude of over 30m.
Battery
Stocked on-site

Holiday/Night

6 Staffs are always
assigned

Number of trainings conducted (as of Oct 28, 2011)

Weekdays

14

Night

3

Weekends

2

Night Training

Permanently Installed
Emergency Generator: 4 units● Reflection of Training
・Prepare head lamps for night operation
・Improve the shape of connection terminal for quicker connection, etc.
● Quicker connection as a result of training
・ Power supply vehicles : 135 mins
⇒Air Cooling Emergency DG：78 mins
(Time to start power supply to all reactors )241

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

2. Secure Cooling Sources: Cooling water for 16 days of operations are secured. Fire
pumps with high portability and large pump* with extremely high capacity are set up for
more multiplicity and diversity. (*: Implemented December, 2011)
Hardware： Multiplexing and Diversifying of Cooling Sources

Software： Training Enforcement

In order to secure low and high heat cooling, and coolant sourcefor 2 types of ultimate heat sinks

In order to operate installed fire pumps andother equipments smoothly

Alternatives ofsea water pump

Supply Capability of Cooling Water

Diversification of
power sources

Additional corecooling system
Securecooling method
For core cooling(High Heat)
For fuel pit
cooling

For corecooling(Low Heat)

For cooling
DG

For feedingwater toauxiliary corecooling System●Establish organizations : Quick assembly under emergency●Prepare manuals andNumbers of trainings conducted (as of Oct 28, 2011)
operate training
・Install pumps
・Lay down hoses
・Operate pumps
・Fuel pumps

SG Feed Water

20

SFP Feed Water

12

Cold Shut Down

4

Pump Installation

Hose Laying● Reflection of Training
Fire Pump:
25 units

Additional Pump:
28 units added

Total fire pumps: 88 units(Including back-ups)* All numbers are per plantPortable Engine
Driven Sea Water
Pump: 30 units
Total: 32 units(Including back-ups)

Large Pump：
1 unit(DG driven, gas oil,self-propelled) (To be
installed in Dec, 2011)

・ Put marks on the points to install pumps.
・ Prepare transceivers for closer communication● Back-up of Sources and Equipments
・ Required fire pumps: 53 units => Total of 88 units were set
・ Required hoses: 631 units => Total of 670 units were242
set
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

2. Securement of Cooling Water: Training for the large volume pump, installed in
December, 2011, and currently in the process of implementation.

Large Pump

Sea Water
Intake Pump

Large Pump

Large Pump

Pump for Sea Water
IntakeWater Intake Tank
for Training(Volume: 150m )3

Sea Water
Discharge Pump
243
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

(Continued)

Water Discharge
Line

Large Volume Pump
Activation

Water Discharge Flow
Meter

Adjustment of Flow
VolumeWater Discharge Outlet
244
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

3. Countermeasure against Flooding: In order to protect emergency DG’s and TD/MDAFWP’s* located at lower level, the waterproof sealing up to the altitude of 11.4m were
implemented . (*: Turbine-Driven Auxiliary Feed-Water Pump, Motor-Driven Feed-Water Pump)
Primary Containment
Vessel<Conceptual Diagram>

Spent Fuel Pit
Turbine Building

Outer

Steam Generator

Battery Room (DC Panel)
Central Control Room
Metal-Clad Gear Room
TurbineCondenser
Container(+26.0m)(+21.8m)(Ground Level:+9.7m)(+15.8m)－ ＋11.4m －(+10.0m)(+3.5m)←EL:0m
Reactor Pressure Vessel

Emergency DG
Turbine-Driven Auxiliary
Feed-Water Pump

Motor-driven Auxiliary
Feed-Water Pump
In case of complete submergence at outside of TD-AFWP room, water level rises 0.3cm/hr.
(from experimental data)

Sealing for Door

Sealing for Pipe Routing

Waterproof Door245
EL.10.0m
BeforeAfter

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

Planned Countermeasures: It is planned or considered to introduce permanently installed
emergency DG at a high place and seismically-Isolated major buildings, as well as toenable all plants to share any of their power sources each other.
MeasureSecurement of Power Source

Securement of Ultimate Heat
Sink

Last Half, 2011

First Half, 2012

Last Half, 2012

Reinforcement of External Transmission
Line

Will respond appropriately based on the detailed research on damage of earthquakes in Fukushima.

Installation of Permanently Installed
Emergency Diesel Generator

Design, research, and conduct site preparation

Reinforcement of Pipelines forCondensate Pit、Purified Water Tank、
Plain Water Tank

March, 2013
Design, ,manufacture, and construct

Building Protection Barrier around
Purified Water Tank and Plain Water
Tank

March, 2013
Design, manufacture, and construct

Back-up Electric Equipments for Sea
Water Pump

March, 2012
Manufacture and install

Implement Large Volume Pump

Install

Securement of Cooling
System of Spent Fuel Pit

Reinforcement of Cooling System for
Spent Fuel Pit

March, 2012
Manufacture and construct

Enforcement ofCountermeasure against
Tsunami, etc.

Heightening existing Breakwater
Enforcement of Countermeasures against
Flooding on the Important
Systems/Functions for Safety
Constructing Protecting Barriers around
Sea Water Pump as a countermeasureagainst Tsunami

Securement ofCommunication Devices in
PlantsRe-location of Communication Systems to
Seismically-Isolated Building

Prevention of Hydrogen
Explosion

Installation of Catalytic Hydrogen
Recombiner System in Containment
VesselMarch, 2012

December, 2011

March, 2014
Manufacture and construct in a sequential order

Manufacture and construct in a sequential order

June, 2013
Manufacture and construct
Around 20162012-2013(Install at periodic inspection)

246
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

Prevention of Core Damage (SBO, Loss of Ultimate Heat Sink): It is now possible to keepcooling the core for 16 days without any off-site supports because of the newly
introduced air-cooling emergency DG and enforced water feed systems.

Before Safety
Measures

Containment vessel
Pressurizer
Steam

Central Control Room

Pressure
vesselSupportFrom Off-Site

After Safety
Measures
Air Cooling Emergency DG(Fuel Tank for 7 days)

In Ooi Nuclear
Power Plant

Outside of Ooi
NuclearPower Plant

Water

Monitoring
Water Level, etc.

燃料

Steam Generator(Eliminate heat in reactor)

Electricity Driven
Auxiliary Feed
Water Pump

Turbine Driven Aux.
Feed Water Pump

Heavy Oil Tank
(Fuel Stock for 85
days)

Battery

Secondary
System-C
Purified
Water Tank

Secondary
System Purified
Water
Tank (Back-up)

Gasoline
Storage Room

【By Air】
Helicopter【By Land】
Truck

Fire Pump
Condensate
Pit【By Land】
Tanker Lorry

Sea Water

Furthermore, it would also be possible to keep cooling the core beyond 16 days with247
additional supplies such as gasoline for fire pump from off-site.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

(Cont.) It is also possible to keep cooling the spent fuel pit for 10 days without any offsite supports with the air-cooling emergency DG, water source from various tanks, andfire pump.
Cooling of Spent Fuel Pit

Before Safety
Measures

After Safety
Measures
Fire Hydrant

Feeding water to keep thelevel of water

Primary
Purified
Water
Tank

Primary
Feed Water
Pump

Support From
Off-Site
No.1
Plain Water
Tank

In Ooi Nuclear
Power Plant

Heavy oiltank

Air Coolingemergency DG

Outside of Ooi
NuclearPower Plant【By Land】
Tanker Lorry

Spent Fuel Pit
Gasoline Storage
Room

Pump

【By Air】
Helicopter

Coolant
Fire Pump

Pump
Coolant
Cool water cooled by seawater: Can not activate or lose its
function due to power loss

【By Land】
Truck

Sea Water

Furthermore, it would also be possible to keep cooling the pit beyond 10 days with248
additional supplies such as gasoline for fire pump from off-site.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR: Current Situation in Ooi No.3, No.4

Prevention of Hydrogen Explosion: KEPCO* simulates that the hydrogen would notaccumulate to its detonation density even if 75% of all the zirconium used in the fuel rods
were reacted because of the large volume of containment vessel. (*: Kansai Electric Power Company)

Ventilation
Pipe

Annulusventilation
systemReactorContainment
VesselFilter Unit

Findings from Fukushima Daiichi accident
Inside of Containment● An enormous amount ofhydrogen was generated
due to core damage, andaccumulated in thecontainment vessel.

Countermeasures● The large volume of PWR’svessel reduces hydrogenconcentration and increase
the safety allowance against
explosion.
● In the future, static catalytichydrogen recombiner will be
installed in the vessel to lower
hydrogen density.

Hydrogen Leaks

Outside of Containment● Hydrogen leaked to thereactor building surrounding
3
Volume: Approx. 72,900m ( Ooi No. 3,4) the containment vessel, andexploded.
Annulus Section

Volume of containment vessel of Ooi
reactor No.3 is about 5 times as large as theone of BWR with the same output of
1,100,000 kW.

● Hydrogen would be ventilated
to outside by preparing
ventilation procedure in theannulus Section.
● The air cooling emergency DG
supplies power for the ventilation.

249

The vessel will be further reinforced by installing a static catalytic recombiner in the future.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Multiplicity
Multiplicityand
andDiversity
Diversityin
inSafety
SafetyMeasures
Measuresof
ofNuclear
Nuclearand
andIndustrial
IndustrialSafety
SafetyAgency
Agency(NISA)(NISA)Case
CaseStudy
StudyininOoi
OoiNuclear
NuclearPowerPowerPlant
Plant
Reactors
ReactorsNo.
No.33and
andNo.
No.44

250
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

The project examined the multiplicity and diversity of safety measures directed by NISA
at the end of March and at the beginning of April, 2011, in terms of ten categories which
had the greatest impact on the event progression in the Fukushima Dai-ichi accident.

Infrastructure
Supply of Power●● External
ExternalPowerPowerSource
Source●● AC
ACPower
PowerSource
Source●● DC
DCPower
PowerSource
SourcePrimary Functions of Reactor●● Parameter
ParameterMonitoring
Monitoring(Central(CentralControl
ControlRoom)
Room)●● Core
CoreCooling
Cooling●● Pressure
PressureReduction
Reduction ofof
Steam
SteamGenerator
Generator(SG)(SG)

Supply of Coolant●● Sources
SourcesofofCoolant
Coolant●● FuelFuel (Heavy(HeavyOil,
Oil,Light
LightOil,
Oil,
Gasoline)
Gasoline)●● Sea
SeaWater
WaterRelated
RelatedSystem
System(Ultimate(UltimateHeat
HeatSink)
Sink)●● Prevention
Preventionof
ofHydrogen
Hydrogen
Explosion
Explosion

251
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

It is important to examine three different levels of the multiplicity and diversity.
1. Multiplicity anddiversity in one single
emergency stage.
ple:
Exam ergency
Em
se of Source.
a
c
n
I
r
Powe

Reactor
No.1

Reactor
No.2

・
・
・

2. Multiplicity and diversity
among different emergency
stages in one single plant.

For Normal Use(Accident)

For Emergency(Severe Accident)● Emergency DG x2● Air Coolant 1,Water Coolant x1● 1 on 1st Fl., 1 on 2nd Fl.

● Back up DG vehicle for
emergency x2● Set outside at different
places on different levels.

3. Multiplicity and diversity
among several plants by
sharing safety measures.
For Extreme Emergency(Extremely Severe Accident)(Including Off-Site Support)● Portable DG vehicle x2● Portable within 24 hours from
off-site.

● Emergency DG x2● Air Coolant x1, Water Coolant x1● Can share with other reactors

Areas Not Coveredin Current Stress
Tests
Level of importance in education and training to operate safety measures for severe accidents.

Large
Continuous education and training, and proficiency-check are also important to 252
increase multiplicity and diversity of safety measures.

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Summary of Multiplicity and Diversity: Safety measures for “normal” and “emergency”
have been established. Further enhancements are necessary for “extreme emergency”
and trainings.
Extreme Emergency
Emergency
Normal Use(Design Basis)(Accident Management)(Off-Site Support)● Power Source
・External power(4 lines from 2 systems)
・Emergency DG (2 units)
・DC power (batteries) (2 systems)● Power Source
・Power supply vehicle upland (1 unit)
・Air-Cooling emergency DG (2 units)・Permanently-installed emergency DG(1 unit)● Power Source
・Carry in necessities such asbatteries, and fuel from off-siteby helicopter etc.

● Cooling Systems:
High Heat Shut Down
・TD-AFWP (1 unit)
・MD-AFWP (2 units)
・Primary steam relief valve(4 units)● Cooling Systems:
High Heat Shut Down
・MD-AFWP (2 units. Powered byair-cooling emergency DG)
・(Makeshift medium-pressure pump
(Under planning) )● Cooling Systems
・Carry in fuel etc from off-site.

● Cooling Systems:
Low Heat Shut Down
・Residual heat removal pump
(2 units)
・Reactor Building Auxiliary
Cooling Water Pump (4 units)
・Sea Water Pump (3 units)● Coolant System:
Low Heat Shut Down
・Large Volume Pump
(1 unit in a whole plant)(as alternative for sea water pump)・Portable fire pump
(Direct water supply to SG. 1 unit)● Water Source
・Condensate Pit (1 unit)・Pure Water Tank for Secondary
System (5 units in a whole plant)● Water Source
・Water tank (5 units in a whole plant)
・Sea water
・Portable fire pump

● Water Source
・(Carry in water from off-site.)・(Supply from nearby river, lake,ponds.)(Supply sea water to condensate pit)

From the next page, the multiplicity and diversity in each primary function will be 253
examined based on the Accident in Fukushima Dai-ichi.

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of External Power: They plan to enable all the reactors to shareany of external power sources based on the Fukushima Dai-ichi accident.
Ooi Power Plant
No.4

No.3

No.2

● Three independent lines from three different

No.1

transformer stations serve the Ooi Nuclear PowerOoi Branch Line
(77kV)

Plant.
Main Transformer
Switching Station
Sub Transformer

Ooi Main Line
12km Obama Transformer Station (500kV)- Two independent lines from only one

Starting Transformer
Wakasa Bay
Ooi Main Line-2(500kV)transformer station served the Fukushima Dai-ichi
Nuclear Plant.

Keihoku Switching Station

45km

West Kyoto
Transformer Station

63km

Ooi
Main Line-2● If either of the switching stations does not
Ooi
Main LineOoi Branch Linefunction, reactors No. 1 and 2 can share their 6.6

77kVkV AC power with the other. Reactors No. 3 and4 can do the same.

500kV Bus

500kV Bus● In addition, there is a plan to enable all the

Main
Transformer
No.1,2 No.3,4
Back-up Back-up
Transformer Transformer

Starting
Transformer

6.6kV Bus

6.6kV Bus

reactors No. 1 to 4 to share their 6.6 kV AC powerwith each other.

House
Transformer

6.6kV Bus

(Underground cable is being considered as a mid-

6.6kV Bus

to long-term plan.)
A

DG

B

Emergency Power
Source For No.1

A

DG

B

Emergency Power
Source For No.2

A

DG

B

Emergency Power
Source For No.3

A

DG

B

Emergency Power
Source For No.4
Planned254
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of AC Power: The safety allowance has been improved by power
supply vehicles and air-cooling emergency DG’s. Further enhancement is planned to
introduce permanently installed emergency DG.
Air-coolingemergency DG(No. 3 & 4)

EquipmentPowersupplyvehicleNo.4 No.3

Altitude(m)

Drive
MethodWater
Protection

No.1

・ Emergency DG

2

E/B

10.0

WaterCooled

In
Operation

・ Power supply
vehicle2

Outdoor

33.3

AirCooledUpland・ Air-Coolingemergency DG

2Outdoor

33.3

AirCooledUpland1

IndoorUplandAirCooledUplandSwitching Station

Permanently installed
emergency DG (No. 3 & 4)

Wakasa Bay
Permanently installed
emergency DG (No. 1 & 2)

Reactor Containment
Air-coolingemergency DG

Emergency

Permanently installed
emergency DG

Steam Turbine

Install
Location

NormalUse

Emergency DG(No. 3 & 4)

No.2

#

(+26.0m)(+15.8m) (+18.1m)(+10.0m)(+3.5m)Emergency DG

ExtremeEmergency(+21.8m)

・ Permanently
installed
emergency DG(Planned)
・ Generators for
emergency(off-site)

255
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of DC Power: Methodology to secure DC is biased on charging fromAC, though DC batteries are set at 15.8m, where flooding is less likely. It would benecessary to enhance the availability of highly portable batteries*.
Air-coolingemergency DG(No. 3 & 4)

No.4 No.3

No.2

No.1

NormalUsePowersupplyvehicleEquipment

Emergency DG(No. 3 & 4)

Install
Location

Altitude(m)Drive Method

Water
Protection

C/B

15.8

DC

Done

E/B
C/B

15.8
10.0

AC

Under
construction

・ DC Power Source(Safety System)

2・ Charge from DG(Metal-Clad)(DG Control Panel)

2・ DC Power Source(Normal Use)・ Charge from air-coolingemergency DG

1

C/B

15.8

DC

Done

1

C/B

15.8

AC

Done

・ Charge frompermanently installed
emergency DG (MetalClad)

1

C/B

15.8

AC

UplandSwitching Station

Permanently installed
emergency DG (No. 3 & 4)

Wakasa Bay
Permanently installed
emergency DG (No. 1 & 2)

Air-coolingemergency DG(+21.8m)(+15.8m) (+18.1m)(+10.0m)(+3.5m)Extreme Emergency(+26.0m)

Battery DG Control
Plate

Emergency

Reactor Containment

Permanently installed
emergency DG

Steam Turbine#

・ Back-up Battery (Carryin from off-site byhelicopter. Land routeand sea route are being
planned.)DC

Metal-Clad256※: For example, portable batteries, connection port, and cables could be stored in the central control room in order to secure parameter-monitoring function.
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of Cooling Water: Since all the coolant sources are set above
18.5m and hold for 16-days of amount, its safety margin is high.
Plain watertank (No. 1-3)

Secondary purified
water tank

Sea water
No.4

No.2

No.1

Sea water

Normal Use

Condensatepit (No.4)

No.3

Condensatepit (No.3)
Switching Station

Equipment#

Install
Location

Alt.
(m)

Drive Method

Water
Protection

・ Condensate pit

1

E/B

26.0

Unnecessary

Done・ Secondary pure watertank

1

Outdoor

80.5

Unnecessary

Upland・ Plain water tank*3

Outdoor

80.5

Unnecessary

Upland・ Sea water

-

－

－

Unnecessary－

・ Water pit for fuelexchange

1

E/B

18.5

UnnecessaryDone・ Make-up purified watertank (Back-up)*

2

Outdoor

80.5

Unnecessary

Wakasa Bay

Emergency

Purified/plain
water tankfor secondary system

Reactor Containment
Condensate pit
Steam Turbine(+21.8m)(+15.8m) (+18.1m)(+10.0m)(+3.5m)Extreme Emergency(+26.0m)

・ Make-up water from
off-site

Unnecessary*: Numbers per plant

257

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of Fuel (heavy oil, light oil, gasoline): The stockpile offers anadequate safety margin. It would be important to enforce operations and trainings foron-site and off-site logistics under extremely severe accidents.
Gasoline forfire pump

No.4

Fuel tank for
adjunct boiler

No.3

Altitude(m)Drive Method

Water
Protection

Outdoor(Underground)

2.6

Unnecessary

Done

2
※

Outdoor

33.3

Unnecessary

Upland1
14Outdoor
Outdoor
Outdoor

14.4
33.3
45.0

Unnecessary
Unnecessary
Unnecessary

UplandUplandUpland－－－Equipment#

Install Location

・ Stock tank for DG fuel(Heavy Oil)

2・ Fuel tank for back-up
boiler (Heavy Oil)・ Fuel storage (Drumcans for fire pumps are
stored in 6 different
locations)

No.1

NormalUse

Fuel tankfor DG

No.2

Gasoline forfire pump

Switching Station

Gasoline forFire Pump

Wakasa Bay

Emergency

Reactor Containment(+26.0m)(+21.8m)(+15.8m) (+18.1m)

ExtremeEmergency

Steam Turbine

・ Fuel for emergency(Carry gasoline, orlight oil from off-siteby helicopter, landroute or sea route.)－－(+10.0m)(+3.5m)* Numbers
per plant

258
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of Ultimate Heat Sink: While the safety margin of sea water pump
(normal use) is low as located near the sea, the margin for large volume pump (emergency use) is
high. It is also effective to have the open air as the ultimate heat sink.
Large volume pump
Sea water
No.4

No.3

No.2

Sea water pump
(No. 3,4)

No.1

Back-up parts for sea
water pump & motor

Wakasa Bay

Portable fire pump(at Yoshimi tunnel)

Steam Turbine

Emergency

Reactor Containment

Water
Protection

4.65

Electricity
drivenProtection wallfrom Tsunami

Outdoor

33.3

Heavy oilUpland88*

Outdoor(In Tunnel)

62.8

Gasoline

Upland1

Outdoor

32.0

Electricity
drivenUpland#Install Location

・ Sea water pump3

Sea Water
Pump Pit(Intake)・ Large volume pump

1*・ Portable fire pump・ Motors for sea water
pump (Back-up)

NormalUse

Switching Station

Drive Method

Equipment

Altitude(m)(+26.0m)(+21.8m)(+10.0m)(+3.5m)ExtremeEmergency(+15.8m) (+18.1m)

・ Portable waterproof
pump(Water intake fromwatering pit)

Electricity
driven* Numbers
per plant

259
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

PWR

Extremely Confidential

Multiplicity and Diversity of Parameter-Monitoring (Central Control Room): Since thefunction to monitor essential parameters must not be lost in any situation, DC power
supply to the central control room is extremely essential.
Operation panel for air-coolingemergency DG (No. 4 & 3)#

Install
Location

Alt. (m)Drive
MethodWater
Protection

・ Central control room・ Power panels formonitoring instrument
・ DG

1
4
2

C/B
C/B
E/B

21.8
15.8
10.0

DC、AC
DC、AC
AC

Done
Done
Under
installation

・ DC batteries(Rechargeable Battery)

2

C/B

15.8

DC

Done

・ Air-cooling emergency DG

2Outdoor

33.3

ACUpland・ Power supply vehicle*

2

Outdoor

33.3

ACUpland・1

In Building

Upland

AC

－

C/B

21.8

DC

Equipment

Power supply
vehicle

No.4

No.3

No.2

No.1

NormalUse

Switching Station
Wakasa Bay
Operation panel forpermanently installed
emergency DG (No. 1 & 2)

Operation panel forpermanently installed
emergency DG (No. 3 & 4)

Reactor Containment
Air-coolingemergency DG

Emergency

Permanently installed
emergency DG

Central controlroom(+26.0m)(+21.8m)(+15.8m) (+18.1m)

ExtremeEmergency

Steam Turbine

Permanently installed
emergency DG(Installed in the future)

・ Portable batteries(Connected to the
instrument directly)

UplandDone(+10.0m)(+3.5m)Power panels
for monitoring
instrument* Numbers per plant
DC batteries

260
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of Core Cooling: As both open air and ocean are available for
UHS*1, safety margins (both normal and emergency) are high. TDAFWP*2, which does notneed any power is extremely important among high-pressure cooling functions.

Large volume
pump(*1: ultimate heat sink. *2: turbine driven auxiliary feed water pump)

Air-coolingemergency DG(No. 3 & 4)#

InstallLoc.

Altitude(m)

Drive
MethodWater
Protection

1
2

E/B
E/B

3.5
10.0

Steam
Electricity

Done
Done

2

E/B

3.5

Electricity

Done・ Makeshift middle pressure pump(under planning)

1

E/B

17.0

Heavy OilDone

・ Electricity driven auxiliary feed water pump(powered by air-cooling emergency DG)

1

E/B

10.0

Electricity

Done・ Large volume pump1

Upland33.3

Heavy Oil

Upland・ Residual heat removal pump
(Powered by air-cooling emergency DG)

1

E/B

3.5

Electricity

Done・ Auxiliary reactor cooling water pump
(Powered by air-cooling emergency DG)

1

E/B

3.5

Electricity

Done・ Portable fire pump
(Directly feed water to SG)

４

Upland63.0

EngineUplandEquipment
High Heat Shut Down

No.4

No.3

No.2

No.1

NormalUsePowersupplyvehicle(2 units)

Emergency DG(No. 3 & 4)・ Turbine driven auxiliary feed water pump
・ Electricity driven auxiliary feed water pump
Low Heat Shut Down
・ Residual heat removal pump

Switching Station
Wakasa Bay

High Heat Shut Down

Portable fire pump(at Yoshimi tunnel)
Reactor Containment

Steam Turbine

Emergency

Air-coolingemergency DG(+26.0m)(+21.8m)(+15.8m) (+18.1m)(+10.0m)(+3.5m)Turbine driven
auxiliary feedwater pump

Auxiliary reactor
cooling water pump
Electricity driven auxiliary
feed water pump

ExtremeEmergency

Middle and highpressure pump
(17.5m)Residual heatremoval pump

Low Heat Shut Down

・ Water pump vehicle(Transferred from other plants)

261
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of Pressure Reduction of SG*1: Safety allowance of MSR*2 valve(air-pressure) is high since it can be operated by hand. It will be further enhanced withback-up compressor and greater emphasis on operational training. (*1: steam generator. *2: main steam relief)

No.4

No.3

No.1

Equipment

Switching Station
Wakasa Bay

MSR valve(No.3)MSR valve・Electric by-pass valve
・Air compressor
Steam Turbine

Emergency

Reactor Containment

NormalUse

MSR valve(No.4)

No.2#

Install Location

Alt.
(m)

Drive Method

Water
Protection

Air

Done

・ Main steam relief
valve (air-pressured)

4

Main steam
control room incontrol building

33.6

・ Main steam relief
valve(Manual operation)

4

Main steam
control room incontrol building

33.6

Done
Manual handle(Air compressor)

Makeshift air(Setting of electricby-pass valve, etc.)

DC battery(charged by aircooling emergency
DG)(+26.0m)(+21.8m)(+10.0m)(+3.5m)ExtremeEmergency(+15.8m) (+18.1m)

・ Carry in compressor
from off-sites

262
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Multiplicity and Diversity of Prevention of Hydrogen Explosion: This is the comprehensive
assessment of each function. The most important is that “the power source and coolant
shall be secured no matter how severe a circumstance is.”

No. 4

No. 3

No .1

Switching Station
Wakasa Bay

Reactor Containment

Emergency

Static hydrogen
recombiner

Equipment#

Install
Loc.

Alt.
(m)

Drive Method

Water Protection

・ Containment vessel

1

－

－

－

Done

・ Annulus air ventilation fan

2

E/B

22.0

Electric

Done・ Hydrogen purge line incontainment

1

E/B

33.6

Air-operated

Done・ Static catalytic hydrogen
recombiner(Being planned)

5

C/V

－

Unnecessary

Unnecessary(In Containment)

NormalUse

Hydrogen purge line
in containment

No. 2

Annulus ventilation fan(+26.0m)(+21.8m)(+15.8m) (+18.1m)(+10.0m)

Extreme Emergency

Steam Turbine(+3.5m)263
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Path of Sea Water: Since paths for water intake/discharge are located in the sameplace in all plants, diversification would be more effective such as portable pumps etc.
蒸気発生器保管庫
Steam
Generator
Storage Perforated
有孔堤
Dike
Ｂ

Ooi Nuclear Power Plant

Ａ

A 固体廃棄物貯蔵庫
Solid
Waste Storage

Plain/Purified
淡水・純水タンク
Water Tank

B

C

Water 放水口
Discharge
Reactor
Building
原子炉建屋

７７kV
送電線
７７kV送電線
Electric Line

No.4
4号

Reactor
Building
原子炉建屋

No.3
3号

2号 No.1
1号
No.2

タービン建屋

タービン建屋

Turbine Building

No.1,2
1,2号機
号機
1,2
循環水ポンプ
取水口
3,4号機
号機
No.3,
4
3,4
Water
IntakeSwitching
開閉所Station
1,2号機
1,2号機
3,4号機
3,4号機
No.1,2
No.3,
4

５００kV
送電線
５００kV送電線
ElectricLine

協力会社事務所

Offices of Related
Company

Circulation
Water Pump

エルパークおおい“おおいり館”

SeawaterDesalination Unit
海水淡水化装置
淡水・純水タンクPlain/Purified
Water Tank

物揚岸壁

Mihama Nuclear Power Plant
0100

Takahama Nuclear Power Plant

200m

Water Incharge(No. 1~4)

Water
Incharge(No. 3)

Water
Discharge(No. 1, 2)

Water
Incharge(No. 1, 2)

Water Intake(No. 1，2)

Water
Discharge(No. 1, 2)
Water
Discharge(No. 3)

Water
Discharge(No. 3, 4)

Water Intake(No. 3, 4)

264
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

Logistics for Emergency such as Heliport & Fire Pumps: Though their locations, carryin route, and procedures are defined in the manual, it is important to enhance theirproficiencies through trainings.

蒸気発生器保管庫
Steam
Generator Storage
Ｂ

Perforated
有孔堤 DikeＡ

Solid
Waste Storage
A 固体廃棄物貯蔵庫
Plain/Purified
淡水・純水タンク
Water Tank

B

Heliport(Field in Plant)

CElectric Line
７７kV
送電線
７７kV送電線

Water 放水口
Discharge

Reactor
Building
原子炉建屋
No.4

Reactor Building
原子炉建屋

No.3

3号

No.2
2号 No.1
1号

タービン建屋

タービン建屋

4号

Turbine Building

No.1,2
1,2号機
号機
1,2
循環水ポンプ
取水口
No.3,
4
Water
Intake
3,4号機
号機
3,4

Switching Station
開閉所

1,2号機
1,2号機
3,4号機
No.1,2
3,4号機
No.3,
4

Electric
５００kV
送電線 Line
５００kV送電線

協力会社事務所
Offices of Related
Company

Circulation Water
Pump

Seawater Desalination Unit
海水淡水化装置

エルパークおおい“おおいり館”

物揚岸壁

0

100

淡水・純水タンクPlain/Purified
Water Tank

200m

265
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

PWR

Extremely Confidential(Assume it does not work)

24

Loss of cooling function
Coolant leaks into PCV

Prepare LPCI
& low-heat
shutdown (hrs – wk)

Water level goes down.
Fuel rods start exposed.

Temperature andpressure in PCV rise

1

Core damage starts
with massive FP & H2

Cooling of PCV
by fire pumps etc
H2 leaks into
annulus from PCV
Hydrogen explosion
at annulus

24

Preparation
Watering and Cooling ofContainment by Fire Pump, etc.
Establish
hydrogenventilation

Fission products
released●Core cooling by electricity driven AFWP

Transport extra power supply vehicles, power panels,
pumps, fuel etc by air as needed (w/inhrs).

Countermeasur
e for flooding

Bring in more supplies to continue high-pressure cooling. Securesufficient power source. Repair accesses.
● Continue high-pressure cooling (TD-AFWP) (= No power needed).
● Secure back-up high-pressure cooling (MD-AFWP) (Activate air-cooling DG).
● Boric acid is injected automatically from accumulator tank at 4.2MPa of corepressure. (No power needed).
● Open/close MSR valve as core pressure drops. (Secure communication means).
● Temporarily stop cooling at 1.7 MPa (secure communication means). Close
electric exit-valve of accumulator tank (use air-cooling emergency DG).
● Then, open MSR valve & restart cooling (secure communication means).
● Repair & secure access by heavy machineries.
● Prepare to inject sea water into condensate pit.
● Carry in and secure DC power & fuel for a few days to a week.

●

Loss of all power(DC, emergency DG)

Keep high pressure coolinghours)(Within

Set at Altitude
15.8m

5

5

Additional supplies and supports for heavymachineries etc. (Secure access).

Tsunami Hits

Secure power (for second use). Continue cooling by HPCI● Activate & connect air-cooling emergency DG to panels (Securecommunications).
● Bring in & connect additional batteries (Enhance DC power source).
● Continue high pressure cooling (TD-AFWP) (= Need no power).

3

Transport back-up DG/batteries, power panels etc
by air. (Have to be compact and highly portable,
w/in
hrs by on-site DC runs out.)

Automatic activation of
emergency DG

Secure power (for initial use) & functions of control room and TDAFWP (turbine-driven auxiliary feed water pump).
● Scram is assumed to succeed.
● Open MSR valve and activate TD-AFWP by DC power (= start High
Pressure Cooling System) before Tsunami hits (=DC is active).
● Stand-by or connect portable batteries in the central control room.
● Establish system to overview the damage of all power systems.

HPCI(W/in hrs)

Loss of all external
power (AC)Emergency Shutdown
of Reactor

Assumes the event progresses till here.

Earthquake occurs

Initial Action(W/in hrs)

Assumed Event Progression●

Assuming the same accident in Fukushima Dai-ichi reactor-1, most of the current safetymeasures in Ooi reactor 3 & 4 would be effective and most likely could avoid a majore
AM actions (On-site)
accident.
mpl(Off-site)
Exa

24

Prepare to transfer to core de-pressurization & low-pressure cooling● Set up low-pressure-cooling lines. Prepare alternative water source (fire pump etc).
● Open/close MSR valve & maintaining 0.7 MPa of core pressure (securecommunication means). Prepare alternative sea water source (large volume pump).
Reduce core pressure. Start low-pressure cooling to low-heat shut down.
● Use feed-and-bleed to SG or RHRS to low-heat shutdown.
Red= Current safety measures are effective.

● Diversify emergency DG/DC● Set storage for severe AM at onsite upland● Daily trainings.
(principle, location, height etc).
(power sources, power panels, pumps, fuel etc.)(Quantified efficiency test)● Prepare protective clothing, masks, ● Enforce water protection (breakwater, water stops● Secure communication methods.
dosimeters etc.
for building, watertight doors etc.)● Enhance seismic-durability, diversity, and● Diversify water source and path.
flexibility of external power.
● Install hydrogen detector.

266

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

PWR

Extremely Confidential

Key findings from the simulation in the previous page.

●● Assuming
Assumingthe
thesamesameaccident
accidentwith
withFukushima
FukushimaDai-ichi
Dai-ichireactor-1,
reactor-1,safety
safetymeasures
measuresof
ofOoi
Ooireactors
reactors3&4,
3&4,emergency
emergency
DG’s,high-pressure
cooling,manualoperationofvalve,
automatic
injection
of
boric
acid,
and
ultimateheat
DG’s, high-pressure cooling, manual operation of valve, automatic injection of boric acid, and ultimate heatsink
sink
would
be
effective.
would be effective.
・・ Cooling
Coolingsystems
systemsand
andultimate
ultimateheat
heatsink
sink(open(openair)air)dodoNOTNOTrequire
requirefunctions
functionsnear
nearseaseaside.
side.The
Theheatheatradiation
radiationdoesn’t
doesn’tinclude
includeradioactive
materials.
radioactive materials.
・・ High
Auxiliary Feed Water Pump) doesn’t require any power. 16-days amount of water is stocked
Highpressurepressurecooling
coolingsystemsystem(Turbine-Driven(Turbine-Driven Auxiliary Feed Water Pump) doesn’t require any power. 16-days amount of water is stocked
already.
already.
・・ Valves
Steam Relief valve) can be operated manually. They are outside of the containment vessel and easy to
Valvesfor
forhigh-pressurehigh-pressurecooling
cooling(Main(Main Steam Relief valve) can be operated manually. They are outside of the containment vessel and easy toaccess.
access.
tank)・・ As(Accumulator tank)
Ascoolingcoolinggoes,
goes,boric
boricacid
acidisisautomaticallyautomaticallyinjected
injectedinto
intothethecorecorewithout
withoutanyanypower
poweratataaset
setpressurepressurelevel.
level.(Accumulator
・・ 22air-cooling
air-coolingemergency
emergencyDG
DGfor
foreacheachreactor
reactorare
aresetsetup
upfar
farfrom
fromseasea(at(at33.3m).
33.3m).Connecting
Connectingports
portsareareready
readytotoplug
plugininjust
justnext
nexttotothe
the
DG.
DG.
●
● The
Theactivation
activationof
ofair-cooling
air-coolingDG
DGand
andTD-AFWP
TD-AFWPmust
mustbebedonedoneasassoonsoonasaspossible
possibleafter
afterdisasterdisasteroccurs.
occurs.No
Nofailure
failureisis
allowed.
allowed.
・・ Right
Rightafter
afterthethereactor
reactorscram
scram(before(beforeTsunami,
Tsunami,DCDCisisstill
stillactive),
active),TD-AFWP
TD-AFWPmust
mustbebeactivatedactivated(needs(needsDC),
DC),andandMSR
MSRvalve
valve(needs(needsairairpressure,pressure,ororby
byhand)hand)must
mustbebeopened
opened(=(=completion
completionofofultimate
ultimateheat
heatsink
sink&&high-pressurehigh-pressurecooling
coolingsystem).
system).These
Thesearearedesigned
designedtotostart
start
automaticallyautomaticallyduring
duringscram.
scram.
・・ Air-coolingemergency
Air-cooling emergencyDG
DGmustmustbebeactivatedactivatedand
andconnectedconnectedtotothe
thepanelpanelnext
nexttotoititby
byhandhand(=(=set-up
set-upofofemergency
emergencyAC
ACpower
powersupply).
supply).
・・ Portablebatteries(easy
tocarry)
forthecentralcontrol
room
must
be
preparedtobeplugged
in
for
DC
power
loss
(=
securePortable batteries (easy to carry) for the central control room must be prepared to be plugged in for DC power loss (= securemonitoring).
monitoring).
●● ThereThereare
areNo
Noalternatives
alternativesto
toDC
DCbatterybatteryand
andTD-AFWP.
TD-AFWP.They
Theymust
mustnotnotbe
belost.
lost.
・・ There
is
only
one
DC
battery
room
(with
2
systems).
If
it
is
lost,
the
essential
parameters
There is only one DC battery room (with 2 systems). If it is lost, the essential parameterscan
cannotnotbebemonitored.
monitored.Even
Eventhoughthoughthetheroomroom
isislocatedat
15.8m,
itisimportanttoenhanceits
multiplexity
anddiversity.
located at 15.8m, it is important to enhance its multiplexity and diversity.
・・ TD-AFWP
TD-AFWP(at(atthethebottom
bottomfloor)
floor)isisthetheonly
onlymeansmeansforforsupplying
supplyinghigh-pressurehigh-pressurecoolant
coolantunder
underpower
powerloss.
loss.Absolute
Absolutesafety
safetymeasures
measurestotosecureAuxiliary Feed Water Pump) would be available.)secureitsitsfunctionality
functionalityare
areessential.
essential. (If(Ifair-cooling
air-coolingDG
DGworks,
works,two
twoMD-AFWP
MD-AFWP(Motor-Driven(Motor-Driven Auxiliary Feed Water Pump) would be available.)
●
● As
Asthe
theplant
plantisisatatthe
theendendof
ofpeninsula,peninsula,ititisisvery
veryimportant
importantto
tosecure
securethe
therobustness
robustnessand
andaccessibility
accessibilityof
ofthe
the
267
transportation
route
to
carry
in
machineriesorothernecessities
from
each
storagedepot.
(Enforce
off-sitetransportation route to carry in machineries or other necessities from each storage depot. (Enforce off-site
supports).
supports).
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

PWR

A respectable extent of diversification and multiplexing of power source and coolant istaking place. For further enhancement, the following issues would be effective.
●● Sharing
Sharingof
ofequipments
equipmentsand
andfunctions
functionsamong
amongseveral
severalreactors.
reactors.
**
**
**
**

Flexible
Flexiblepower
powersource
source(external(externalpower,
power,emergency
emergencyDG,
DG,battery,battery,power
powerplate).
plate).(This(Thisisisbeing
beingplanned).
planned).
Flexiblewater
source(condensate
water
pit,
pure
water
tank,
fire
extinguishing
water
etc).
Flexible water source (condensate water pit, pure water tank, fire extinguishing water etc).
Flexible
Flexibleemergency
emergencyequipments
equipments(power(powersupply
supplyvehicle
vehicleetc).
etc).
Settingunderground
cable
for
external
power
supplyin
mid
Setting underground cable for external power supply in midtotolong
longtermterm(for(forearthquake
earthquakecountermeasures).
countermeasures).

●● Enhancement
Enhancementof
ofdiversification
diversificationand
andmultiplexing
multiplexingininseawater
seawaterintake
intakeandanddischarge
dischargeroute
routefor
foritsits
geographic
advantageoffacingthebay.
geographic advantage of facing the bay.
**
**
**

E.g.:
E.g.:Enable
Enablewater
waterintake
intakefrom
frombothbothintake/discharge
intake/dischargesides
sidesvia
viaunder-water
under-waterpumps.
pumps.
Securemakeshiftresourcesandmachinessuchasportableboosterpump
withSecure makeshift resources and machines such as portable booster pump withpermanent
permanentconnection
connectionstations.
stations.
Securemakeshiftpowersourcepanels,power
supplyvehicles,
cables,under-water
pumps,
boosterpumps,
Secure makeshift power source panels, power supply vehicles, cables, under-water pumps, booster pumps,
bellows
bellowsplumbing
plumbingetc.
etc.

●● MoreMorediversification
diversificationand
andmultiplexing
multiplexingof
ofAuxiliary
AuxiliaryFeed
FeedWater
WaterPump
PumpandandDC
DCpower
powersource,
source,which
which
are
the
life
lines
of
the
plant.
are the life lines of the plant.
**
**
**

TurbineTurbineDriven
DrivenAuxiliary
AuxiliaryFeed
FeedWater
WaterPump:
Pump: Water-proof
Water-proofprocessing
processingasasprevention.
prevention.Preparing
Preparingstanding
standingstocks
stocksofofback-up
systems
andequipmentsasmitigation.
back-up systems and equipments as mitigation.
DC
DCBattery:
Battery: Same
Sameasasabove.
above.Essential
Essentialtotosecure
secureback-up
back-upDC
DCpower
powerconsidering
consideringthe
thecasecaseofofpower
powerpanels
panelsbeing
being
submerged.
submerged.
DC
DCPower
PowerSource
SourcePanel
PanelSystem:
System:Same
Sameasasabove.
above.
268
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

PWR

Extremely Confidential(Continued)●
essentialto
toexamine
examinethe
theissues
issuesbelow
belowtotopreventpreventhydrogenhydrogenexplosion?
explosion?
● IsIsititessential****

ItItisiseffective
effectivetotoprepare
prepareandandtrain
trainsafety
safetymeasures
measurestotoreduce
reducehydrogenhydrogenininthe
thecontainment
containmentvessel
vesselwith
withits
its
operation
procedure
defined,eventhoughitwill
notattaindetonationlevel
accordingtopreliminary
calculations.
operation procedure defined, even though it will not attain detonation level according to preliminary calculations.
ItItisisalso
alsothethesamesameforforthethehydrogenhydrogenexplosion
explosionininthe
theannulus
annulussection
sectioninincase
caseofofHH2 2leakage.
leakage.
(E.g.:
Whatshould
be
done
when
the
motor
is
disabled?)(E.g.: What should be done when the motor is disabled?)●● Diversification
Diversificationand
andMultiplexing
Multiplexingof
ofoff-site
off-sitesupport.
support. (Must(Mustbebepreparedpreparedwith
withoperating
operatingprocedures
andpractical
training).
procedures and practical training).
****

PreparePrepareandandtrain
traintotouse
usethethesecondsecondororthird
thirdheliportheliportinincase
casethetheprimaryprimaryheliportheliport (＝(＝closerclosertotothe
theoceanoceanthan
thanreactor
No.1)
is
lost
by
Tsunami.
reactor No.1) is lost by Tsunami.
SecureSecuretransportationtransportationroutes
routesfrom
fromheliportheliportsmoothly.
smoothly.(For(Forheavy
heavymachineriesmachineriestotoremove
removerubble,
rubble,and
andtotostrengthen
strengthen
pathways)pathways)●● Ensure
Ensureliving
livingenvironment
environmentsuch
suchasasdrinkabledrinkablewater,water,etc.
etc.
**
**

Some
Somenuclear
nuclearplants
plantsuse
usethetheseawater
seawaterdesalination
desalinationunit
unitforfordrinking
drinkingwater.
water.
Securealternative
means
to
avoid
any
disturbancein
plant
operation
Secure alternative means to avoid any disturbance in plant operationby
bylosslossofofpower
powerororofofsea
seawaterwatersystem,
system,causingdegradationoflivingenvironment.
causing degradation of living environment.

●● ThisThiscasecasestudy
studywaswasconductedconductedonly
onlyunder
underone
oneassumption
assumptionof
ofearthquake
earthquakeandandtsunami,
tsunami,that
thatisisthethesamesamelevel
levelasasthe
theoneoneininthe
theFukushima
FukushimaDai-ichi.
Dai-ichi.There
Therearearevarious
variouspossibilities
possibilitieswhich
whichcancancause
SevereNuclearAccidents,suchasTerrorist
Attacks,
Crash
of
Jet
Airplanes,etc.
cause Severe Nuclear Accidents, such as Terrorist Attacks, Crash of Jet Airplanes, etc.
Verifications
Verificationsunder
undervarious
variousother
otherassumptions
assumptionsare
areabsolutely
absolutelynecessary.
necessary.
269
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

PWR: References…

Extremely Confidential

Major References (PWR)
Nuclear and Industrial Safety Agency (See Homepage)
・
・
・
•
・
・
・

The Results of Confirmation for the Implementation of the emergency safety measures for other Nuclear Power Stations Based on the
Accident in Fukushima Dai-ichi Nuclear Power Station (May 6, 2011)
Regarding Verification of the Implementation of Countermeasures for Severe Accidents in Other Nuclear Power Stations Taking into
Account the Accident at Fukushima Dai-ichi NPS (June 18, 2011)
Regarding Reliability Assurance of External Power Supply to Nuclear Power Stations and Reprocessing Facilities (April 15, 2011)
Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety - The Accident at TEPCO's Fukushima Nuclear
Power Stations (June 7, 2011)
Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety - The Accident at TEPCO's Fukushima Nuclear
Power Stations (The Second Edition) (September 11, 2011)
Regarding the Implementation of Comprehensive Assessments for the Safety of Existing Power Reactor Facilities Taking into Accountthe Accident at Fukushima Dai-ichi Nuclear Power Station, Tokyo Electric Power Co. Inc. (July 21, 2011)
Hearing on Comprehensive Assessment for the Safety of Nuclear Power Reactor Facility(http://www.nisa.meti.go.jp/english/index.html )Report from The Kansai Electric Power Co. Inc (See Homepage)
・
・
・
・
・
・

Regarding the Current Nuclear Power Plant Situation and Safety Measures Considering the Accident in Fukushima Dai-ichi and Dai-ni
Nuclear Power Station (April 27, 2011)
Regarding the Securement of Reliable External Power Source to Nuclear Power Plant (May 16, 2011)
Regarding the Measures to Respond to a Severe Accident based on the Accidents in Fukushima Dai-ichi Nuclear Power Plant (June 14,
2011)
Regarding Comprehensive Safety Assessment on Ooi Nuclear Power Plant No.3 (October 28, 2011)
Regarding Comprehensive Safety Assessment on Ooi Nuclear Power Plant No.4 (November 17, 2011)
Regarding Operation of Safety Measures of Software Side Considering the Accidents in Fukushima Dai-ichi Nuclear Power Plant(November 28, 2011)
270
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

The
TheFirst
FirstStressStressTest
Test
by
bythe
theNuclear
Nuclearand
andIndustrial
IndustrialSafety
SafetyAgency
Agencyatatthe
theMinistry
MinistryofofEconomy,
Economy,Trade
Tradeand
andIndustry
Industry

271
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Nuclear and Industrial Safety Agency (NISA) Stress Test

Extremely Confidential

In this chapter the following 4 points are overviewed on the First Stress Test directed
by NISA●● Current
Currentsituation
situationofofthe
thestress
stresstest
test (ST)(ST)ininJapan
Japan●● Current
Currentsituation
situationofofthe
thestress
stresstest
test (ST)(ST)ininEU
EU●● Issues
Issues●● Points
Pointstotobe
beconsidered
consideredorormodified
modified

The following pages will discuss these points.

272
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Nuclear and Industrial Safety Agency (NISA) Stress Test

Stress Tests in Japan: No specific judgmental criteria is defined even though it is
the prerequisite for reactivation of the nuclear power plant.
●● After
Afterimplementing
implementingvarious
variouscountermeasurescountermeasuresininresponse
responsetotothe
theaccident
accidentininFukushima,
Fukushima,thetheNuclear
NuclearandIndustrial
SafetyAgency(NISA)
recognized
it
is
not
enoughtoobtainpublicacceptance,and Industrial Safety Agency (NISA) recognized it is not enough to obtain public acceptance,and
anditit
instructed
instructedthe
theoperation
operationofofthe
thecomprehensive
comprehensiveendurance
endurancetest
test(=(=stressstresstest).
test).
●● The
TheStress
StressTest
Testconsists
consistsofofthe
thePrimaryPrimaryTest
TestandandthetheSecondary
SecondaryTest.
Test.
・・ Primary
Test:
Prerequisiteforjudgmentofreactivationforreactors
Primary Test: Prerequisite for judgment of reactivation for reactorsundergoingundergoingperiodic
periodicinspection.
inspection.
・・ Secondary
Test:
Requirementforjudgmentofcontinuous
operation
or
halt
for
all
the
existing
Secondary Test: Requirement for judgment of continuous operation or halt for all the existing
nuclearnuclearplants
plantsandandnuclear-related
nuclear-relatedfacilities.
facilities.
●● By
ByDecember
December20,
20,2011,2011,thethetesttestresults
resultshave
havebeen
beensubmitted
submittedfrom
from77plants,
plants,andand44power
powercompanies,
companies,
such
as
for
Ooi
No.
3
and
4,
and
Ikata
No.
3.
NISA
is
deliberating
theseresults.
such as for Ooi No. 3 and 4, and Ikata No. 3. NISA is deliberating these results.
●● The
TheNuclear
NuclearSafety
SafetyCommission
CommissionofofJapan
Japan(NSC)(NSC)has
hasrequested
requestedthe
thecomprehensive
comprehensivesafety
safetytest,
test,
includingassumptions
beyondits
designconcepts,
andthereportontheassessment
methodincluding assumptions beyond its design concepts, and the report on the assessment methodand
and
implementation
implementationplan
planbasedbasedononthe
thearticle
article25
25ininEstablishment
EstablishmentAct
ActofofJapan
JapanAtomic
AtomicEnergy
EnergyCommission(AEC),
andNuclear
SafetyCommission.
Commission (AEC), and Nuclear Safety Commission.
●● The
TheStress
StressTest
Testexamines
examinesmainly
mainlythe
thesafety
safetyallowanceallowanceagainst
againsteacheachreactor’sreactor’sdesign
designassumptions
assumptionstoto
ananearthquake,
earthquake,tsunami,
tsunami,losslossofofall
allAC
ACpower
powersource,
source,losslossofofultimate
ultimateheat
heatsink,
sink,andandcombinations
combinationsofof
these
theseevents.
events.
●● No
Nospecificspecificjudgmental
judgmentalcriteria
criteriaisisdefined
definedininthis
thistest
testeven
eventhoughthoughititisisthe
theprerequisite
prerequisiteforforreactivationof
each
nuclearpower
plant.
reactivation of each nuclear power plant.

273

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Nuclear and Industrial Safety Agency (NISA) Stress Test

Comprehensive Safety Assessment (Stress Test): Summary of primary tests whichhave been submitted so far (as of the end of December, 2011)
Item

Cliff Edge Effect (After Emergency Safety Measure Operations)

Assessment Index
Tomari No.1

Earthquake (Reactor)

Comparison withStandard Ground
Motion (Ss)

Tsunami (Reactor)

Comparison with
Supposed Tsunami
HeightSuperposition ofEarthquake andTsunamiSuperposition of 2
Events Above

Ooi No.3

Ooi No.4

Ikata No.3

1.86 Times

1.80 Times

1.80 Times

1.86 Times(Power Distribution
Board)
Sｓ:550gal(High-Voltage Switchgear) (High-Voltage Switchgear) (DC Power Source
Ss:700gal
Ss:700gal
System)Ss:570gal(Condensate Water Tank) (Low-Voltage Circuit
Ss:540gal
Breakers)
Ss:540gal(Low-Voltage Circuit
Breakers)
Ss:540gal

1.53 Times

4.0 Times

6.19 Times

4.05 Times(Power Distribution
Board, etc.)
Supposed Tsunami
Height9.8m(Turbine Driven Auxiliary (Turbine Driven Auxiliary (Turbine Driven Auxiliary (Turbine Driven Auxiliary (Turbine Driven Auxiliary (Turbine Driven Auxiliary
Feed Water Pump)
Feed Water Pump)
Feed Water Pump)
Feed Water Pump)
Feed Water Pump)
Feed Water Pump)
Supposed Tsunami
Supposed Tsunami
Supposed Tsunami
Supposed Tsunami
Supposed Tsunami
Supposed Tsunami
Height2.85m
Height2.85m
Height3.49m
Height2.1m
Height3.7m
Height3.7m

Same as Above

Same as Above

4.0 Times

Same as Above

4.06 Times

Same as AboveGenkai No.2

1.75 Times

Same as Above

Sendai No.1

1.86 Times

4.05 Times

Same as Above

Sendai No.2

1.89 Times

Same as Above

Approx.20 Days Approx.16 Days Approx.16 Days Approx.10.7 Days Approx.65 Days Approx.104 Days Approx.104 Days

Loss of All AC Power
Source (Core)(Fuel for Alternative
Power/Water Feeding(Light Oil))(Fuel for Make-up Water (Fuel for Make-up Water (Fuel for Power Source
Pump (Gasoline))
Pump (Gasoline))
Car (Heavy Oil))(Fuel for High-Voltage
Generator Car (Heavy
Oil))(Fuel for High-Voltage
Generator Car (Heavy
Oil))(Fuel for High-Voltage
Generator Car (Heavy
Oil))

Approx.10 Days Approx.10 Days Approx.8.2 Days Approx.65 Days Approx.104 Days Approx.104 Days
(Fuel for Make-up Pit
Water Pump (Gasoline))

Loss of All AC Power
Source (Spent Fuel)
Cooling Time without
Off-Site Support

Loss of Ultimate Heat
Sink (Core)(Fuel for Make-up Pit
Water Pump (Gasoline))(Fuel for FireExtinguishing Vehicle(Light Oil))(Generator Fuel for(Generator Fuel for
Makeshift Pump (Gasoline Makeshift Pump (Heavyand Heavy Oil))
Oil))(Generator Fuel for
Makeshift Pump (Heavy
Oil))

Approx.142 Days Approx.16 Days Approx.16 Days Not Causing Fuel

Approx.378 Days Approx.939 Days Approx.939 Days

(Fuel for Alternative Feed (Fuel for Make-up Water (Fuel for Make-up Water
Pump (Gasoline))
Pump (Gasoline))
Water (Light Oil))(Generator Fuel for(Generator Fuel for
Makeshift Pump (Gasoline Makeshift Pump (Heavyand Heavy Oil))Oil))

Rod Damage(Generator Fuel for
Makeshift Pump (Heavy
Oil))

Approx.10 Days Approx.10 Days Approx.28 Days
Loss of Ultimate Heat
Sink (Spent Fuel)(Fuel for Make-up Pit
Water Pump (Gasoline))(Fuel for Make-up Pit
Water Pump (Gasoline))(Fuel for Sea Water
Make-up Pump to Plain
Water Tank (Gasoline))

274

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Nuclear and Industrial Safety Agency (NISA) Stress Test

Extremely Confidential

Current Stress Test in EU: Stress tests in EU consist of two layers, EU-common and nation
specific. Neither are requirements for plant reactivation. The purposes are to recognize
strengths and weaknesses of each plant and to develop safety measures.
●● On
OnMarchMarch25,
25,2011,2011,responding
respondingtotothe
theFukushima
FukushimaDai-ichi
Dai-ichiNuclear
NuclearPowerPowerPlant
Plantaccident,
accident,thetheEuropean
EuropeanCouncil
CouncilrequestedtheEuropeanCommission
(EC)
and
the
European
Nuclear
SafetyRegulatoryGroup(ENSREG)definethetherequested the European Commission (EC) and the European Nuclear Safety Regulatory Group (ENSREG)totodefinestresstest
specifications
toretestthesafetyallowanceofthenuclearpower
plants.
stress test specifications to retest the safety allowance of the nuclear power plants.
●● BasedBasedononthe
thespecifications,specifications,thetheelectric
electricpower
powerproviders
providersininEU
EUwillwillreportreportthethetesttestresult
resulttotothe
theregulatory
regulatoryauthorities
authoritiesinin
eacheachcountry.
country.Each
Eachcountry
countrywill
willsummarize
summarizethemthemand
andreport
reporttotothe
theEC
ECwhichwhich ininturn
turnwill
willreportreporttotothe
theEuropean
EuropeanCouncil.
Council.
After
all
the
phasedreports,
thefinalreporttotheEuropeanCouncilwillbesubmitted
in
June,
2012.
After all the phased reports, the final report to the European Council will be submitted in June, 2012.
●● All
Allregulatory
regulatoryauthorities
authoritiesacrossacrossallallcountries
countriesare
arepreparing
preparingthe
theresults
resultstotothe
theEC
ECby
byDecember
December31,
31,2011,2011,totorecognize
recognizethe
thesafetyallowanceoftheplant.
safety allowance of the plant.
●● WithWiththetheearthquake
earthquakeandandtsunami
tsunamiset
setasasinitiating
initiatingevents,
events,thethetesttestassesses
assessesthe
thecliff-edge
cliff-edgeeffects
effectsofofsubsequent
subsequentevents
events
such
as
the
loss
of
external
power,
thelossofultimate
heat
sink,
and
eventscombined.
Based
on
the
test
results,such as the loss of external power, the loss of ultimate heat sink, and events combined. Based on the test results,the
theEU
EU
will
developand
implement
furthercountermeasures.
will develop and implement further countermeasures.
●● The
Thedifferences
differencesfrom
fromthetheJapaneseJapaneseStressStressTests
Testsare:are:(1)(1)initiating
initiatingevents
eventsinclude
includenot
nottsunami
tsunamibut
butflood,
flood,and
and(2)(2)thethepurposeisnotaprecondition
for
plant
reactivationbutthedevelopmentoffurthersafetymeasures.
purpose is not a precondition for plant reactivation but the development of further safety measures.
●● Stress
StressTests
Testsininthe
theEU
EUconsistconsistofoftwo
twolayers,
layers,EU-common
EU-commontests
testsandandandandtests
testsinineacheachnation.
nation.The
Theformer
formerisisapplies
appliescommonlyinallEU
nationsandallthereportsaremadeavailabletothepublic.
On
the
other
hand,
the
lattercommonly in all EU nations and all the reports are made available to the public. On the other hand, the latterincludes
includesnot
only
safetymeasuresbut
also
security,
and
is
not
requiredtosubmittheresults
totheEuropeanCouncil,or
not only safety measures but also security, and is not required to submit the results to the European Council, ortotomake
makeititavailable
tothepublic.
available to the public.
275
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Nuclear and Industrial Safety Agency (NISA) Stress Test

Issues of Stress Tests in Japan: Current stress test does not consider uncertain elements
such as a human error, or inefficient performance caused by lack of training.
●
●As
Asthe
thestress
stresstest
testapplies
appliesthe
thedeterministic
deterministicapproach,approach,uncertainties
uncertaintiessuch
suchasashumanhumanerrorserrorsarearenotnotconsidered.
considered.

- - Human
Humanerror:
error: Effectiveness
Effectivenessand
andreliability
reliabilityofofmanual
manualoperations
operationssuch
suchasastotoconnect
connectcables
cablesororopen
openvalves.
valves.
- - Proficiency
ofoperatorsontechnology
andaccident
management
gainedthroughtraining.
(Can
staff
Proficiency of operators on technology and accident management gained through training. (Can staffoperate
operatethethesystems
appropriately?)systems appropriately?)- - Risk
Riskofofsimultaneous
simultaneousaccidents
accidentsininmultiple
multipleplants.
plants.
- - Effectivenessof
supports
andsafetymeasures
Effectiveness of supports and safety measuresfrom
fromoff-sites.
off-sites.

●●In
Inotherotherwords,
words,doesn’t
doesn’tthethecurrent
currentstressstresstest
teststandstandononthe
thefollowing
followingunspoken
unspokenassumptions?
assumptions?

- - Examples-1：
Examples-1：Once
Oncethey
theycarry
carryininthe
thecables,
cables,they
theycancanalways
alwaysconnect
connectthem
thembybyhands.
hands.
- - 2：
Once
installed,
deviceswhich
requirecomplicatedoperations
willfunction,
2： Once installed, devices which require complicated operations will function,regardlessregardlessofofthe
theproficiencies
proficienciesofof
operatingoperatingstaff.
staff.
- - 3：
Once
implemented,
3： Once implemented,safety
safetymeasures
measureswill
willalways
alwayswork
workequallyequallywhether
whetherananaccident
accidentoccurs
occursininaasingle
singleplant
plantoror
severalseveralplants
plantssimultaneously.
simultaneously.
- - 4：
Effectiveness
4： Effectivenessofofoff-site
off-sitesupport
supportdoes
doesnot
notaffectaffectthe
thesafety
safetyallowanceallowanceand
andcliff-edge
cliff-edgeofofthe
theplant.
plant.
(On(Onthetheotherotherhand,
hand,ififaa10-meter
10-meterwaterproof
waterproofdoor
doorisisinstalled,installed,aacomplete
completeloss
lossofoffunction
functiondue
duetotoflooding
floodingwill
will
occur
once
the
level
of
water
goes
even
slightly
beyond10m.)
occur once the level of water goes even slightly beyond 10m.)●●The
Thestress
stresstest
testisiseffective
effectiveforfortechnicaltechnicalassessment
assessmentsuch
suchasasthe
thesafety
safetymargin
marginofofthe
theplantsandfunctionstoenhanceor
improve.
However,
it
does
not
cover
all
the
issuesplants and functions to enhance or improve. However, it does not cover all the issues
necessarynecessaryto
toconsider
considerfor
forthetheprevention
preventionof
ofseveresevereaccidents
accidentsas
asFukushima
FukushimaDai-ichi.
Dai-ichi.
276

Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Nuclear and Industrial Safety Agency (NISA) Stress Test

In order to secure “enough power and core cooling under any severe circumstance”, it isnecessary to examine the following issues at the corporate, government and municipality
levels.
●● Can
Canstaff
staffnecessary
necessaryfor
foraccident
accidentmanagement
management(both(bothininplant
plantandandheadquarters)
headquarters)bebeassembled
assembled
withinwithinthe
thespecified
specifiedtime
timeeven
evenononholidays
holidaysororatatnight?
night?
●● Can
Canstaff
staffrespond
respondtotoan
anaccident
accidentininsufficientsufficientnumbers
numbersand
andinineacheachprofessional
professionalroleroleevenevenifif
accidents
accidentshappen
happensimultaneously
simultaneouslyininseveral
severalororall
allplants?
plants?
●● For
Forsecurement
securementofofpower
powersources,
sources,arearethey
theypreparedpreparedtotoprotect
protectand
andsupply
supplyenoughenoughfuelfuelnonomattermatterhowhowsevere
severethe
theaccident
accidentis?
is?
●
● For
Forsecurement
securementofofthe
theultimate
ultimateheat
heatsink,
sink,arearethey
theypreparedpreparedtotoprotect
protectand
andsupply
supplyenoughenoughfuelfuelnonomatterhow
severetheaccidentis?
matter how severe the accident is?
●● Can
Canthey
theyrecover
recoverororprepare
preparepower
powersource
sourceasaswellwellasasultimate
ultimateheat
heatsink
sinkwithin
withinthe
thespecified
specifiedtime?
time?
●
● Are
Areperiodic
periodictrainings
trainingsconductedconductedtotoachieve
achievethe
theagenda
agendaabove,
above,and
andmanaged
managedininPDCA
PDCAcycle
cycle
methodforfurtherenhancement?
method for further enhancement?
●● Can
Cangovernment
governmentand
andmunicipalities
municipalitieswork
worktogether
togethertotoestablish
establishemergency
emergencyorganization
organizationtoto
procureprocureandandtransporttransportnecessary
necessarysupplies
suppliestotothe
theaccident
accidentsite
sitewithin
withinthe
thespecified
specifiedtime
timelimit?
limit?
277
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Conclusion
Conclusion

278
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Conclusion…

Extremely Confidential

Conclusion●
lessonlearned
learnedfrom
fromthetheFukushima
FukushimaDai-ichi
Dai-ichiNuclear
Nucleardisasterdisasterisisnot
notthatthatwe
wehad
had
● The
Thebiggest
biggestlesson
underestimated
the
risk
of
Tsunami,
but
that
we
had
lackedthedesignphilosophy
statingunderestimated the risk of Tsunami, but that we had lacked the design philosophy stating“we“wehavehave
toprevent
severenuclearaccidentsnomatterhow
extremethecircumstances”.
Howeverhigh
weto prevent severe nuclear accidents no matter how extreme the circumstances”. However high we
setsetourourassumptions,assumptions,there
therewill
willalways
alwaysbe
beaapossibility
possibilityof
ofananevent
eventthat
thatexceeds
exceedsthem.
them.
●● Having
Havingclarified
clarifiedwhat
whathappened
happenedininFukushima
FukushimaDai-ichi,
Dai-ichi,weweshould
shouldstop
stoprelying
relyingso
somuchmuchonon“Probability
Theory”
and“assumptions
on
the
scale
of
events”,
such
as
for
the
heightof“Probability Theory” and “assumptions on the scale of events”, such as for the height ofthe
thetsunami
tsunamiwhen
designingthesafetymeasures.
Thisisespeciallysoconcerninganaccidentthatcauseswhen designing the safety measures. This is especially so concerning an accident that causes
irreparable
irreparabledamage
damageto
tosocietysocietyor
orour
ourdailydailylives.
lives.
●● InInorder
ordertotopreventpreventaadisasterdisasterlike
likeFukushima
FukushimaDai-ichi
Dai-ichifrom
fromevereverhappening
happeningagain,
again,weweshould
shouldredefine
redefinethedesignphilosophy
andfundamental
safetyprinciple
ofnuclearpower
plantsto:“Powersourcesthe design philosophy and fundamental safety principle of nuclear power plants to: “Power sources
andandcooling
coolingfunctions
functionshave
havetotobe
besecured
securedunder
underanyanysevere
severecircumstance”.
circumstance”. InInother
otherwords,
words,“severe“severeaccidents
must
beprevented
nomatterhow
severe
the
event
that
occurs”.
Anynuclearplant
accidents must be prevented no matter how severe the event that occurs”. Any nuclear plantwhich
which
can
not
fulfill
thiscondition
shouldnotbereactivated.
can not fulfill this condition should not be reactivated.
●● We
Wehavehavetotoimmediately
immediatelyexamine
examinethe
the“diversity“diversityand
andmultiplicity”
multiplicity”(=(=multiplicity
multiplicityof
ofsafetysafetymeasures
measuresusing
different
principles)
of
all
of
the
nuclearplants.
Based
on
that,
we
shouldestablish
using different principles) of all of the nuclear plants. Based on that, we should establishthree
three
stagesofaccident
management,“During
NormalUse",“During
Emergency",
and“During
Extremestages of accident management, “During Normal Use", “During Emergency", and “During Extreme
Emergency".
Emergency".
・・ ForForananExtreme
ExtremeEmergency,
Emergency,accident
accidentmanagement
managementshould
shouldinclude
includeoff-site
off-sitesupport
supportby
bynot
notonly
onlythetheelectric
electricpower
power
providers
but
also
the
centralgovernment
and
local
municipalities.
providers but also the central government and local municipalities.
・・ We
Weshould
shouldestablish
establishaareal-timereal-timenetwork
networksystemsystemwhich
whichenables
enablesall
allofofthe
thestakeholders
stakeholdersabove
abovetotoshare
shareinformation
informationandandco-conduct
decision-making.
The
networkmust
beavailable
immediately
after
entering
Accident
Management(AM)
co-conduct decision-making. The network must be available immediately after entering Accident Management (AM)
mode.
mode.
279
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Conclusion…

Conclusion●causeofofthe
thenuclear
nuclearaccident
accidentininFukushima
FukushimaDai-ichi
Dai-ichiisisthethebasic
basicdesign
designconcept
concept● The
Thedirect
directcause
createdby
the
Nuclear
SafetyCommissionofJapan,
thatstates,“Itisnotnecessarycreated by the Nuclear Safety Commission of Japan, that states, “It is not necessaryto
toconsider
the
case
of
long-term
loss
of
all
AC
power
sources”.
When
was
it
decided,andconsider the case of long-term loss of all AC power sources”. When was it decided, andhow
how
was
it
acceptedandallowedtobeappliedfordecades?
Its
responsible
stakeholders,thewas it accepted and allowed to be applied for decades? Its responsible stakeholders, themechanismmechanismof
ofdecision
decisionmaking
makingandandgovernance,
governance,its
itscausecauseand
andprevention
preventionshould
shouldbe
beuncovered.
uncovered.
●● Staff
Staffininthe
thefieldfield(such(suchasasthe
thenuclear
nuclearplants,
plants,power
powerproviders,providers,andandmanufacturers)
manufacturers)could
couldhave
have
madegreaterefforts
toenhancethesafetymeasuresbefore
March
11.
Since
they
“assumed”
made greater efforts to enhance the safety measures before March 11. Since they “assumed”
too
toomuchmuchregarding
regardingthe
theearthquake
earthquakeandandtsunami,
tsunami,they
theycould
couldnotnothavehavehadhadaarealistic
realisticgrasp
graspof
of
what
a
“Real
Emergency”
is.
Of
the
severalcases
introduced
previouslyin
thisreport,thisiswhat a “Real Emergency” is. Of the several cases introduced previously in this report, this is
one
oneof
ofthe
themostmostregrettable.
regrettable.
・・

All
Alloutside
outsideuptake
uptakepower
powersupplies
supplieswent
wentunder
underwater.
water.=>=>TheyTheyshould
shouldhave
havebeen
beensetsetatathigher
higherpositions,
positions,andand
someshouldhave
beenwaterproofed.
some should have been waterproofed.

・・

At
AtFukushima
FukushimaDai-ichi,
Dai-ichi,even
eventhoughthoughreactor
reactorNo.1
No.1hadhadaadifferent
differentvalve
valvesystemsystemininIC/RCICIC/RCIC(fail-close)(fail-close)from
from
the
rest
of
the
reactors(No.2–
6,
fail-open),
staff
in
the
plant
believed
that
the
IC
of
reactorNo.1
would
the rest of the reactors (No.2 – 6, fail-open), staff in the plant believed that the IC of reactor No.1 wouldhave
have
been
working(with
its
internal
valvesopened).
Therefore,
they
might
have
prioritizedtherescueofreactorbeen working (with its internal valves opened). Therefore, they might have prioritized the rescue of reactor
No.2.
No.2.=>=> They
Theyshould
shouldhave
haveunified
unifiedthe
thesystem
systemofofall
allreactors
reactorsasas‘fail-open’.
‘fail-open’.

・・All
Allofofthe
thewater-coolingwater-coolingemergency
emergencydiesel
dieselgenerators
generators(DG)(DG)were
wereofofone
onekindkindandandininone
oneplace.
place.They
Theywere
weretootoofocusedonmultiplicity.
=>
Theyshouldhave
diversified.
focused on multiplicity. => They should have diversified.

280
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Conclusion…

Extremely Confidential

Conclusion●
theoriginator,
originator,thetheEU,
EU,there
thereisisno
nonation
nationwhich
whichutilizes
utilizescomputer
computersimulation-typesimulation-type● Including
Includingthe
stresstests
asapreconditionforrestartinganuclearpower
plant.
The
Japanesestress tests as a precondition for restarting a nuclear power plant. The JapaneseGovernment
Government
shouldreconsider
using
it
as
one
of
its
technologicalverifications.
should reconsider using it as one of its technological verifications.
・・・・StressStressTesting
Testingisiseffective
effectiveforforidentifying
identifyingtechnicaltechnicalitems
itemstotobe
beimproved
improvedininaaplant.
plant.
However,
unpredictableelements
such
as
human
error,
proficiency
level
from
However, unpredictable elements such as human error, proficiency level fromtraining,training,simultaneous
simultaneousaccidents
accidents
ininseveral
plantsandsupportfromoff-site,
are
out
of
the
scope
of
its
simulation
algorithm.
(It
appliesseveral plants and support from off-site, are out of the scope of its simulation algorithm. (It appliesaa
deterministic
deterministicapproach,approach,inputs
inputsofofwhich
whichonly
onlyconsist
consistofofon-site
on-sitemeasurements
measurementsininaasingle
singleplant.)
plant.)●● The
Thecurrently
currentlyimplemented
implementedFirstFirstStressStressTest
Testincludes
includesalmost
almostall
allof
ofthe
theemergency
emergencysafety
safetymeasuresdirectedbythegovernment
since
March
11,
2011.
Therefore,
they
arehighlymeasures directed by the government since March 11, 2011. Therefore, they are highlylikely
likelyto
togetalmostexactlythesameresults
intheSecondStress
Test.
Is
there
any
essential
meaning
get almost exactly the same results in the Second Stress Test. Is there any essential meaning
ininconducting
conductingthe
theSecond
SecondStressStressTest
Testafter
afterthethefirst
firsttest?
test?The
Thegovernment
governmentshould
shouldintegrate
integratethethesecond
test
into
the
first
one.
second test into the first one.
●
● Lessons-learned
Lessons-learnedfrom
fromthisthisresearchresearchareareapplicableapplicableuniversally,
universally,notnotonly
onlyfor
forBWR
BWRplants
plantsbut
butalsoalso
PWR
plants.
PWR plants.
●● ThereTherearearemany
manynuclear
nuclearplants
plantswith
withaasimilar
similardesign
designphilosophy,
philosophy,technicaltechnicalspecifications,specifications,andand
accident
management
measuresglobally.
In
order
to
prevent
anaccident
like
the
one
in
accident management measures globally. In order to prevent an accident like the one in
Fukushima
FukushimaDai-ichi
Dai-ichifrom
fromevereverhappening
happeningagain,
again,thethegovernment
governmentshould
shouldshare
sharethethefacts
factsand
andlessons-learnedin
thisreport
with
the
rest
of
the
world
as
quicklyandaccuratelyaspossible.
lessons-learned in this report with the rest of the world as quickly and accurately as possible.

281
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Conclusion…

Conclusion●
parties,suchsuchasasvarious
variouslocal
localgovernments,
governments,arearenow
nowwaiting
waitingfor
forthetheso-calledso-called● Related
Relatedparties,“Official”
research
reports
currently
ongoing,
oneby
thecentralgovernment“Official” research reports currently ongoing, one by the central governmentand
andthetheotherotherbybythenational
diet.
There
are
an
increasing
numberofvoicessaying“Without
official
reports,
the national diet. There are an increasing number of voices saying “Without official reports,
we
wecan
cannotnotexplain
explainthe
thedetails
detailsof
ofthisthisaccident
accidentwell
wellenoughenoughto
tolocallocalresidents
residentsbased
basedonon
lessons-learnedinthe
Fukushima
Dai-ichiaccident,”
or
“We
want
to
postponeany
discussion
lessons-learned in the Fukushima Dai-ichi accident,” or “We want to postpone any discussion
orordecision
decisionon
onwhetherwhetherthe
thenuclear
nuclearpower
powerplant
plantininour
ourmunicipality
municipalityshould
shouldbe
bereactivatedreactivateduntil
until
the
official
reportsaresubmitted.”
By
Spring,2012,
thecentralgovernment
shouldmakeathe official reports are submitted.” By Spring, 2012, the central government should make adecision
decisionon
onde/reactivation
de/reactivationof
ofthe
thenuclear
nuclearpower
powerplants,
plants,along
alongwithwithplans
plansforforaccident
accident
prevention
andpoliciesforfutureenergysupply.
prevention and policies for future energy supply.
・・
・・
・・

IfIfthethesituation
situationabove
abovecontinues,
continues,there
therewill
willbebeaagreater
greaterpossibility
possibilityofofprocrastination
procrastinationininevenevenstarting
starting
discussions
until
Spring(orSummer),
2012,
by
which
time
the
official
research
reports
andSecondarydiscussions until Spring (or Summer), 2012, by which time the official research reports and SecondaryStressStressTest
willbeproduced.
Test will be produced.
IfIfpublic
publicopinion
opinionrecognizes
recognizesthose
thoseofficial
officialreports
reportsasasinsufficient,insufficient,thethedecision-making
decision-makingwill
willbebepostponed
postponedeven
even
longer.
longer.
InInthisthiscase,case,thetheriskrisktotolife
lifeand
andtotothe
thedomestic
domesticeconomy
economywill
willincrease
increasefurther.
further.

●● ThereThereisissufficientsufficientaccident
accidentdata
dataalreadyalreadyreported
reportedwhich
whichincludes
includesenoughenoughanalyses
analysesof
ofthe
the
facts,
causes,andsafetymeasures.
What
must
be
done
now
is
to
“explain,publicize,andfacts, causes, and safety measures. What must be done now is to “explain, publicize, andtaketakeactions”
actions”based
basedononthesethesefindings.
findings.

282
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Appendix
Appendix

283
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Abbreviations…

Abbreviations of Nuclear Power Plant Terminology
AM:

Accident Management

AO Valve: Air-Operated Valve
BWR:

Boiling Water Reactor

CRD:

Control Rod Drive

CUW：

Reactor Water Cleanup System

CCSW:

Containment Cooling Service Water System

CS:

Core Spray System

D/G，DG： Diesel Generator
DGSW：

Diesel Generator Sea Water System

D/W：

Dry-WellDS Pit：Dryer Separator Pit

D/D FP：

Diesel/Driven Fire Protection Pump

ECCS：

Emergency Core Cooling System

EECW：

Emergency Equipment Cooling Water System

284
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Abbreviations…

FCS：

Flammability Control System

FDW：

Reactor Feed Water System

FPC：

Fuel Pool Cooling and Filtering System

FPMUW： Fuel Pool Make-up Water SystemGal：

CGS unit of acceleration

HPCI：

High Pressure Coolant Injection System

HPCP：

High Pressure Condensate Pump

HPCS：

High Pressure Core Spray System

HPCSS：

HPCS D/G Sea Water System

HPCW：

HPCS D/G Cooling Water System

HPSW：

HPCS D/G Sea Water System

HVE：

Heating Ventilating Exhaust System

IAEA：

International Atomic Energy Agency

IC:

Isolation Condenser

INES：

International Nuclear Event ScalekPa abs：

kilo Pascal Absolute Pressure

LPCS：

Low Pressure Coolant Injection System

285
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Abbreviations…

M/D RFP： Motor Driven Reactor Feed Water Pump
M/C：

Metal-Clad Switch Gear

MO Valve： Motor Operated Valve
MUWP：

Make-Up Water System (Purified)

MUWC：

Make-Up Water System (Condensate)

MSIV：

Main Steam Isolation Valve

P/C：

Power Center

PCV：

Primary Containment Vessel

PWR：

Pressurized Water Reactor

R/B：

Reactor Building

RCIC：

Reactor Core Isolation Cooling System

RCW：

Reactor Building Closed Water System

RD，R/D： Rupture Disk
RHR：

Residual Heat Removal System

RHRC：

RHR Cooling Water System

RHR LPCI mode：

RHR Low Pressure Cooling Injection Mode

RHRS：

RH Sea Water System

RPV：

Reactor Pressure Vessel

RSW：

Reactor Building Closed Cooling Sea Water System

RW/B：

Rad-Waste Building

286
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Abbreviations…

SBO：

Station Black out

S/C：

Suppression Chamber

SFP：

Spent Fuel Pool

SGTS：

Stand-by Gas Treatment System

SHC Mode： Shut Down Cooling Mode
SLC：

Stand-By Liquid Control System

SRV：

Safety Relief Valve

Ss：

Basic earthquake ground motion

TAF：

Top of Active Fuel

T/B：

Turbine Building

TCW：

Turbine Building Closed Cooling Water System

W/W：

Wet WellOuter：

Support buildings surrounding nuclear power plant for auxiliary machines such as DG and power panels.

Ultimate Heat Sink： Substances releasing heat ultimately such as the ocean or the open air, in order to remove decay
heat in the core.
Self Air Set： Air mask to prevent internal exposure during severe work in high dosage level. A set of equipment withoxygen tank.
Electric Penetration: Areas penetrating through walls for routing electric cables to the nuclear reactor containment.
Sloshing：Spilling and splashing of pooled water caused by long period oscillation such as earthquake.
Bag Filter： Filter to eliminate radioactive particulate matter.

287
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedSources and references…

Extremely Confidential

List of the main sources and references
Tokyo Electric Power Company (from website)・
Fukushima Dai-ichi Reactors 1 – 6 plant-related parameters (water level, pressure, temperature, monitored data).
・Effect of the Tohoku earthquake and tsunami on nuclear power plant and current situation.
・Collection of reports based on provisions of Utility Industry Law Article 106, section 3. (May 16 2011)
・
Report on the responding action based on the report on the damage on power equipment in the vicinity of Fukushima Dai-ichi nuclear power plant. (May 23 2011)
・
Analysis and evaluation based on operations and accident records in Fukushima Dai-ichi nuclear power plant during the 2011 Tohoku earthquake. (May 23 2011)
・
Effects of the earthquake and tsunami on the Fukushima Dai-chi and Dai-ni nuclear power plants. (May 24 2011)
・
Chronology of seawater injection at Fukushima Dai-ichi nuclear power plant Reactor 1. (May 26 2011)
・
The research result on the effects of tsunami by the 2011 Tohoku earthquake to Fukushima Dai-ichi and Dai-ni nuclear power plants.
・
Recovery status on Fukushima Dai-ichi and Dai-ni nuclear power plants. (August 10, 2011)
・
Effects on the nuclear reactor facilities at Fukushima Dai-ni nuclear power plant from the 2011 Tohoku earthquake. (August 8, 2011)
・
Effects on the nuclear reactor facilities at Fukushima Dai-ichi nuclear power plant from the 2011 Tohoku earthquake. (September 9, 2011)
・
Analysis on the explosion of nuclear reactor building in Fukushima Dai-ichi nuclear power plant. (October 21, 2011)
・
Research Report on Fukushima Nuclear Plant Accident. (Interim Report) (December 2, 2011)
・
Application Document for the Construction Permit of Fukushima Dai-ichi Nuclear Power Plant, Nuclear Reactor No.1 (Finished Version)
・
Fukushima Dai-ichi Nuclear Power Plant, Nuclear Reactor No.1: The effect of Age Deterioration in Fukushima Dai-ichi Nuclear Power Plant Accident.
(December 15, 2011)
・
Summary of Aging Technology Assessment and Long-Term Maintenance and Management Policy of Fukushima Dai-ichi Nuclear Power Plant, Nuclear Reactor
No.1. (February 7, 2011)
Nuclear and Industrial Safety Agency (from website)・
Examination standards for verifying implementation of emergency safety measures. (May 6, 2011)
・
Examination standards for verifying implementation of safety measures against severe accidents. (June 18, 2011)
・
Security of external power source in nuclear power plants and reprocessing plants. (April 15, 2011)
・
Report of the Japanese Government on cabinet meeting with IAEA in regards to Nuclear Safety – The accident at Tokyo Electric Power Company Fukushima
nuclear power plant. (June 7, 2011)
・
Additional report from the Japanese government to IAEA - The accident at Tokyo Electric Power Company Fukushima nuclear power plants (2nd report).
(September 11, 2011)
・
Comparison of Fukushima Dai-ichi nuclear power plant with other power plants. (June 24, 2011)
・
Discussion Themes of Tokyo Electric Power Co. Inc. (TEPCO)- Fukushima Dai-ichi Nuclear Power Plant Accident, and Hearing Meeting. (October 24, 2011)
・
Damage Situation and Effect to the Safety of Electric Related System in Plant. (November 8, 2011)
・
Damage Situation of Cooling System. (November 25, 2011)

288
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reservedReferences

Extremely Confidential

List of the main sources and references

Japan Nuclear Energy Safety Organization (Homepage)・ 2009 PSA Analysis of Earthquake Level 2 (October, 2010)
http://www.jnes.go.jp/content/000017303.pdf
Japan Nuclear Technology Institute: Research and Review Committee of Fukushima Dai-ichi Nuclear
Power Plant Accident. (Homepage)・ Review and Provision Proposal on Tokyo Electric Power Co. Inc. (TEPCO)- Fukushima Dai-ichi Nuclear Power
Plant Accident (October 28, 2011 )http://www.gengikyo.jp/archive/pdf/F1_Jiko_Houkoku.pdf
Tohoku Electric Power Company (from website)・ Situation of Onagawa nuclear power plant during the 2011 Tohoku earthquake and tsunami. (May 30, 2011)
・
Situation in Onagawa Nuclear Power Plant in November 2011. (December 12, 2011)
Japan Atomic Power Company (from website)
・ Effect of the 2011 Tohoku earthquake on Tokai Dai-ni power plant reactor facilities. (September 2, 2011)
Reference from GE・Design and analysis report

289
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

PWR: References…

Extremely Confidential

List of the main sources and references (PWR)
Nuclear and Industrial Safety Agency (See Homepage)
・
・
・
•
・
・
・

The Results of Confirmation for the Implementation of the emergency safety measures for other Nuclear Power Stations Based on the
Accident in Fukushima Dai-ichi Nuclear Power Station (May 6, 2011)
Regarding Verification of the Implementation of Countermeasures for Severe Accidents in Other Nuclear Power Stations Taking into
Account the Accident at Fukushima Dai-ichi NPS (June 18, 2011)
Regarding Reliability Assurance of External Power Supply to Nuclear Power Stations and Reprocessing Facilities (April 15, 2011)
Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety - The Accident at TEPCO's Fukushima Nuclear
Power Stations (June 7, 2011)
Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety - The Accident at TEPCO's Fukushima Nuclear
Power Stations (The Second Edition) (September 11, 2011)
Regarding the Implementation of Comprehensive Assessments for the Safety of Existing Power Reactor Facilities Taking into Accountthe Accident at Fukushima Dai-ichi Nuclear Power Station, Tokyo Electric Power Co. Inc. (July 21, 2011)
Hearing on Comprehensive Assessment for the Safety of Nuclear Power Reactor Facility(http://www.nisa.meti.go.jp/english/index.html )Report from The Kansai Electric Power Co. Inc (See Homepage)
・
・
・
・
・
・

Regarding the Current Nuclear Power Plant Situation and Safety Measures Considering the Accident in Fukushima Dai-ichi and Dai-ni
Nuclear Power Station (April 27, 2011)
Regarding the Securement of Reliable External Power Source to Nuclear Power Plant (May 16, 2011)
Regarding the Measures to Respond to a Severe Accident based on the Accidents in Fukushima Dai-ichi Nuclear Power Plant (June 14,
2011)
Regarding Comprehensive Safety Assessment on Ooi Nuclear Power Plant No.3 (October 28, 2011)
Regarding Comprehensive Safety Assessment on Ooi Nuclear Power Plant No.4 (November 17, 2011)
Regarding Operation of Safety Measures of Software Side Considering the Accidents in Fukushima Dai-ichi Nuclear Power Plant(November 28, 2011)290
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved

Extremely Confidential

Note) The translation of this report has been done by a limited number of staff and within a limited period of time. If there
are any discrepancies between this translation and the original Japanese report, please refer to the Japanese report forclarifications.

The project would like to extend its special thanks to the following people for their great support in this translation work:
Mr. Kenjiro Ishikawa
Ms. Jewel Naruse
Ms. Seiko Toyama
Mr. Curtis Hoffmann
Ms. Keiko Sato

291
Unauthorized copying or distribution of this file is prohibited. Copyright Team H2O Project all rights reserved