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All Rights Reserved ©2012 The Tokyo Electric Power Company, Inc.

Fukushima Nuclear AccidentFukushima Nuclear AccidentA TEPCO Nuclear EngineerA TEPCO Nuclear Engineer’’s Perspectives Perspective

Presentation to the Nuclear Energy InstitutePresentation to the Nuclear Energy InstituteWashington, DCWashington, DC

July 9July 9thth, 2012, 2012

Kenji TateiwaKenji TateiwaManager, Nuclear Power ProgramsManager, Nuclear Power Programs

Tokyo Electric Power CompanyTokyo Electric Power Company

Washington OfficeWashington [email protected]@tepco.co.jp

2All Rights Reserved ©2012 The Tokyo Electric Power Company, Inc.

My Background

�’90~’96: BS/MS in Nuclear Engineering, Kyoto Univ.

�TEPCO

’96~’00: Fukushima Daini NPS

’00~’02: Nuclear Engineering Dept.

’02~’04: MBA, Stanford Graduate School of Business

’04~’05: Nuclear Engineering Dept.

’05~’11: International Affairs Dept.

’11.9~: Washington DC Office

Pursued “Nuclear

Renaissance”(photo taken in June 2010)

Committed to collaborating

with U.S. nuclear sector on

Fukushima response.


My Engagement in Post-Accident Activities

“Bedroom” of ERC (5/21/11@1F)

IAEA: International Atomic Energy Agency / ERC: Emergency Response Center

Translation of Press Releases (3/11/11@Tokyo-H/Q)

Coordination of IAEA Mission (4/6/11@1F)


My Engagement in Post-Accident Activities (cont’d)

Reinforcing US-Japan Ties(6/15/11@AmbassadorJohn Roos’ Residence)

INPO-IST: Institute of Nuclear Power Operations-Industry Support Team

Presentation to Embassies in Tokyo (6/24/11@Delegation of EU to Japan)

Photo by V.J.LUNA

Discussion with INPO-IST (8/19/11@2F)

“Nothing has been more

important in my career

than supporting TEPCO.”


The Great East Japan Earthquake

[Date/Time]Fri, March 11, 2011 at 2:46pm

[Epicenter]Offshore Sanriku Coast(approx. 180 km from Fukushima NPSs)

[Seismic Energy]Magnitude (M) 9.0

Largest earthquake/tsunami

in recorded history of Japan

[Dead/Missing]Approx. 19,000

1st-ever case to set up

Gov’t Emergency Disaster

Response HQ


Impact of Earthquake to TEPCO Facilities and Tokyo Area

Shutdown:

� Nuclear power stations: 2 (7 units)� Thermal power stations: 7 (12 units)� Hydro power stations: 25� Substations: 8

Immediate Power outage:

� 4 million households (14% of TEPCO’scustomer base)

Rolling blackout:

� 10 days in March 2011Massive interruption of infrastructure

(even in Tokyo area):

� Public transportation� Telecommunication� Food/water supply

Epicenter


U-1U-2

U-3U-4

Fukushima Daini (2F)

Overview of Fukushima Daiichi NPS

and Fukushima Daini NPS

(source) JAIF

U-6U-5

U-1U-2

U-3U-4

Fukushima Daiichi (1F)


Mark-II

modified

Mark-II

modified

Mark-II

modified

Mark-II

Mark-II

Mark-I

Mark-I

Mark-I

Mark-I

Mark-I

Contain

ment

Type

OperatingHitachi1,100BWR-5 1984. 22

OperatingHitachi1,100BWR-51987. 84

OperatingToshiba1,100BWR-51985. 63

OperatingToshiba1,100BWR-51982. 41

2F

OutageFull core offloaded to spent fuel pool

1F

Plant

GE/Toshiba

Toshiba

Hitachi

Toshiba

GE/Toshiba

GE

Main

Contractor

Outage

Outage

Operating

Operating

Operating

Pre-earthquake Status

1,100BWR-51979.106

784BWR-41978. 45

784BWR-41978.104

784BWR-41976. 33

784BWR-4 1974. 72

460BWR-31971. 31

Power

Output

(MWe)

Reactor

Type

Start of

Operation Unit

Overview of 1F and 2F (cont’d)

9All Rights Reserved ©2012 The Tokyo Electric Power Company, Inc. （C)GeoEye

Impact of Earthquake/Tsunami at 1F

�Observed seismic acceleration exceeded the design-basis in limited locations. �Plant responded as designed after earthquake.�No damage to safety-related equipment due to earthquake confirmed to date.

�Tsunami severely flooded most of the major buildings.

�Estimated tsunami height of 13m (43ft) much greater than design-basis of 6.1 m.

�Design-basis (6.1m) based on latest tsunami estimation methodology endorsed by Civil Engineers Society of Japan.

Almost the entire area was flooded

Unit

1Unit

2

Unit

3

Unit

4Unit

6

Unit

5

Radwaste

Processing

building


11 22

33 44

Breakwater

(height: approx. 10m)

Tsunami Observed at 1F


撮影日撮影日撮影日撮影日：：：：2011/3/11 15:42

Tsunami Observed at 1F (cont’d)

撮影日撮影日撮影日撮影日：：：：2011/3/11 15:42 撮影日撮影日撮影日撮影日：：：：2011/3/11 15:43

撮影日撮影日撮影日撮影日：：：：2011/3/11 15:43 撮影日撮影日撮影日撮影日：：：：2011/3/11 15:43 撮影日撮影日撮影日撮影日：：：：2011/3/11 15:44

重油タンク

Date/time: 2011/3/11 15:43 Date/time: 2011/3/11 15:43 Date/time: 2011/3/11 15:44

Date/time: 2011/3/11 15:42 Date/time: 2011/3/11 15:42 Date/time: 2011/3/11 15:43

Tank (height:5.5m)

Ground Level (10m above sea)

Car Stuck in the Building

Tank Fully Submerged


Impact of Earthquake/Tsunami at 2F

Limited area was flooded

（C)GeoEye

Unit 2 Unit 1Unit 3Unit 4

2F

Radwaste

Processing

building

�Observed seismic acceleration smaller than design-basis. �Plant responded as designed after earthquake.�No damage to safety-related equipment due to earthquake confirmed to date.

�Significant damage due to tsunami, but less extreme compared to 1F.�Estimated tsunami height of 9 m much greater than the design-basis of 5.2 m.

Significant

Tsunami run-up


500 kV Disconnector Damaged 275 kV Circuit Breaker Damaged

Earthquake-Induced Damage to Off-site Power

Landslide（（（（C））））GeoEye

1F-6

1F-5

Transmission Line Tower Toppled

Damage at substation, collapse of transmission line tower, etc. led to:� Loss of all off-site power at 1F

� Loss of all but 1 line of off-site power at 2F

Shin-Fukushima Substation

Transmission Lines to 1F-5/6


Power panelCan/can

not be

usedPower panel

Can/can

not be

usedPower panel

Can/can

not be

usedPower panel

Can/can

not be

usedPower panel

Can/can

not be

usedPower panel

Can/can

not be

usedPower panel

Can/can

not be

usedPower panel

Can/can

not be

usedPower panel

Can/ca n

not be

usedPower panel

Can/ca n

not be

used

DG 1A × DG 2A × DG 3A × DG 4A × DG 5A(*2) × DG 6A ×(*2) DG 1A × DG 2A ×(*2) DG 3A ×(*2) DG 4A ×(*2)

DG 1B ×DG 2B

（air-cooled）×(*1) DG 3B ×

DG 4B（air-cooled）

×(*1) DG 5B(*2) ×DG 6B

（air-cooled）○ DG １Ｂ × DG 2Ｂ ×(*2) DG 3Ｂ ○ DG 4Ｂ ×(*2)

－－－－－－－－－－ HPCS DG ×(*2) DG 1Ｈ × DG 2Ｈ ×(*2) DG 3Ｈ ○ DG 4Ｈ ○

M/C 1C × M/C 2C × 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/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/C 2E × －－ M/C 4E × －－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 5SA-1 × M/C 1SA-1 ○ M/C 3SA-1 ○

M/C 5SA-2 × M/C 1SA-2 ○ M/C 3SA-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 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 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 2A-1 × －－－－ 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 1B × P/C 2B ○ P/C 3B × P/C 4B ○ 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 1S × －－ P/C 3SA × －－ P/C 5SA × －－ P/C 1B-2 ○ P/C 2B-2 ○ P/C 3B-2 ○ P/C 4B-2 ○

－－－－－－－－ P/C 5SA-1 × －－ P/C　1SA ○ P/C 3SA ○

－－ P/C 2SB × P/C 3SB × －－ P/C 5SB × －－ P/C　1SB ○ P/C 3SB ○

DC125V mainbus panel A

×DC125V P/C

2A×

DC125V mainbus panel 3A

○DC125V mainbus panel 4A

×DC125V P/C

5A○

DC125V DISTCENTER 6A

○DC125V mainbus panel A




○

DC125V mainbus panel B

×DC125V P/C

2B×

DC125V mainbus panel 3B

○DC125V mainbus panel 4B

×DC125V P/C

5B○

DC125V DISTCENTER 6B

○DC125V mainbus panel B




○

A RHRS A × RHRS A × RHRS A × RHRS A × RHRS A × RHRS A × RHRS A × RHRS A × RHRS A ×

B RHRS B × RHRS B × RHRS B × RHRS B × RHRS B × RHRS B × RHRS B × RHRS B ○ RHRS B ×

SW ×

- -

Regu

lar use

P/C

P/C 1A ×

－

Sea

wate

rsys

temD

C p

ower

supp

ly

125V

DC

Em

ergenc

y DG

M/C

－

Regu

lar useEm

erge

ncy

use

M/C 2SB

M/C 2SA

×

×

×

× M/C 3SA

M/C 3SB

M/C 2B

M/C 3A

×M/C 5BM/C 4B

M/C 5AM/C 4A ×××

××× M/C 3B

M/C 1S ×

M/C 1Ｂ ×

×M/C 2A

Em

ergency use

M/C 1A ×

Unit 3 Unit 5Unit 4 Unit 6

- -

Fukushima DaiichiUnit 1 Unit 2

Fukushima DainiUnit 1 Unit 2 Unit 3 Unit 4

(1F) No off-site power + 1 D/G (2F) One off-site power + 3 D/G

D/G

6.9

kV M

/C480V P

/CD

C

O: operable X: damagedSea Water

Cooling System

Post-Tsunami Power Supply System at 1F/2F

Failure of most of the power

panels made recovery work

extremely difficult.


Amplification of Multiple Tsunami Waves Caused by

Unprecedented Large-scale Earthquake

1050

100150

福島第二

福島第一0

2

4

6

8

10

12

14

水深[m]

Sea Floor

Displacements

Fukushim

a

Daiic

hi

Fukushim

a

Dain

i

Maxim

um

tsunam

i heig

ht

［m

］

Peaks coinciding

↓Tsunami height: High

Peaks not coinciding

↓Tsunami height: Low

(1)

(2)

(3)

Time T

(3)

(2)

(1)

Water depth [m]

(1)+(2)+(3)

Postulated Tsunami Model

No expert/institution predicted large-scale

tsunami source of this magnitude.

1m

5m

20m


Tsunami Warning Stone(Miyako, Iwate Pref.)

(source) http://blog.miyakomall.jp/2012/04/

Fukushima NPSs

No Historical Evidence of Huge Tsunamis

Near Fukushima NPSs

Commonly misquoted“Tsunami Warning Stone” and“Once-in-400-year recurrence of 7-m tsunami”

both refer to locations in Iwate Prefecture, 200 miles north of Fukushima NPS.


c Yahoo JAPAN

b1

b2

c Yahoo JAPAN

Iwate has deep-

indented coastline

that tends to

magnify tsunami

height.

Tsunami Height Heavily Dependent on Coastal Topography

Fukushima has flat

coastline and

historically

experienced

significantly lower

tsunami height

compared to Iwate.


1F Unit 1 Schematic System Diagram (Post-Tsunami Status)

Sea

Tb

Condenser

H/W

Gen

CST

Filtrated

Water

Tank

SLC

Sta

ck

Sea

CCS

D/GCCSW

SRV

CRD

HPCI

CPRFP

CWP

CSMUWC

DD FP

IC

S/C vent

valve

D/W vent

valve

RP

V

from CST＆H/W

Sea

: Operable

: Inoperable

: Briefly operable

• Reactor automatically shutdown after earthquake.

• Earthquake caused loss of off-site power.

• Tsunami caused loss of all emergency power,

rendering most safety systems inoperable.


Sea

Tb

Condenser

H/W

Gen

CST

Filtrated

Water

Tank

SLC

Sta

ck

Sea

RHR

D/GRHRS

SRV

CRD

HPCI

LPCPMD-

RFP

CWP

CS

MUWC DD FP

S/C vent

valve

D/W vent

valve

:Operable

:Inoperative dueto power loss

RP

V

TD-

RFP

from CST＆H/W

CST

RCIC

HPCP

Sea

:Inoperative

Turbine-driven RCIC continued to cool the core

for about 3 days.



Sea

Tb

Condenser

H/W

Gen

CST

Filtrated

Water

Tank

SLC

Sta

ck

Sea

RHR

D/GRHRS

SRV

CRD

HPCI

LPCPMD-

RFP

ＣＣＣＣWＰＰＰＰ

CS

MUWC DD FP

S/C vent

valve

D/W vent

valve

RP

V

TD-

RFP

from CST＆H/W

CST

RCIC

HPCP

Sea

:Operable

:Inoperative dueto power loss

:Inoperative

Turbine-driven RCIC and HPCI continued to

cool the core for about 1.5 days.



PCV Vent

FP/Fire Engine

No OperationSRV

No OperationHPCI

IC

1F Unit 1 Plant Parameter and Operation

（19:04）Sea Water

Order for Vent Preparation （0:06） ▼

（5:46） Fresh Water ［80t］（14:53）

（18:18 - 25）（21:30）(14:52)

Operation Unclear

Order for Vent ▼ （8:03）（14:30） D/W Pr decrease confirmed

0.000

0.200

0.400

0.600

0.800

1.000

3/11 12:00

3/11 18:00

3/12 0:00

3/12 6:00

3/12 12:00

3/12 18:00

3/13 0:00

設計圧力

（0.53MPa abs）

ベント実施圧力

（0.954MPa abs）

0.00

2.00

4.006.00

8.00

10.00

3/11 12:00

3/11 18:00

3/12 0:00

3/12 6:00

3/12 12:00

3/12 18:00

3/13 0:00

逃がし弁機能（7.28,7.35,7.41MPa abs）

設計圧力（8.7MPa abs）

運転圧力（7.0MPa abs）

-3000

-1000

1000

3000

5000

3/11 12:00

3/11 18:00

3/12 0:00

3/12 6:00

3/12 12:00

3/12 18:00

3/13 0:00

原子炉水位（燃料域)(A）（mm）

原子炉水位（燃料域)(B）（mm）

In Operation(Over Scale )In Operation(Over Scale )In Operation(Over Scale )In Operation(Over Scale )

Rx

Wate

r Le

vel [m

m]

● Fuel Range (A) (mm)

● Fuel Range (B) (mm)

● Rx Pressure (A) (MPa)

● Rx Pressure (B) (MPa)

● S/C Pressure (A) (MPa)

● D/W Pressure (B) (MPa)

Earthquake Tsunami Unit 1 R/B ExplosionEstimated beginning of core damage

Rx

Pre

ssure

[M

Pa

]D

/W &

S/C

P

ressure

[M

Pa

]

0(TAF)

• Plant status became unknown after tsunami.

• Inadequate core cooling led to core damage, hydrogen

generation and hydrogen explosion.


Accident Response at 1F<Challenging Condition in Field>

Tsunami-drifted obstacles blocked roads.

Fire hoses laid for reactor water injection restricted field access by vehicles.

Hazardous road conditions.

Challenging conditions

exacerbated by continual

aftershocks/tsunami alerts.


Supervised operation wearing full-face mask.

Checked instrumentation in near-complete darkness.

Accident Response at 1F<Challenging Condition in Main Control Room>

Brought in heavy batteries to restore instrumentations.

• Lack of:

instrumentation, communication

means, lighting, food, water, sleep, ...

• Increase in:

radiation level, fatigue, fear, despair, ...


Accident Response at 1F<Containment Vessel Venting in Unit-1>

Protective gears upon entering reactor building.

72AO

ボンベ

210MO ラプチャーディスク

排気筒

1AO

ボンベ

閉

閉

83AO

閉

閉90AO

0.549MPabsで破壊

RPV

D/W

RPVRPV

D/W

IA

IA

D/W最高使用圧力0.528MPabs

ベント実施圧力0.954MPabs

電磁弁

電磁弁

213AO

Attempt to

open manually

MO

AO

AO

AO

AO

MO

Exhaust stack

Closed

Closed

Closed

Closed

Solenoid valve

Solenoid valveC

ylinder

Cylin

der

D/W maximum operating pressure:

0.528MPa-abs

Rupture disc

ruptures at 0.549MPa-abs

Venting pressure:0.954MPa-abs

�Six men formed 3 teams to manually open 2 valves in

highly-radioactive area to vent containment.

�Core damage estimated to have progressed by time of

this action (3/12 9:04-9:30).

Self-contained breathing apparatus


Accident Response at 1F<Containment Vessel Venting in Unit-1 (cont’d)>

R/B 2nd levelR/B 1st level

Air lock

To 2nd level

by stairs PCV vent

valve

(MOV)

Access Route to PCV Vent Valve (MOV)

1st team’s attempt to manually open PCV vent valve (motor-operated valve).

Successful. (3/12 9:15)

Reactor Core

Reactor Core


Accident Response at 1F<Containment Vessel Venting in Unit-1 (cont’d)>

R/B 1st level R/B B1F

S/C vent

valve

(AOV)

Access Route to S/C Vent Valve (AOV)

Air lock

2nd team’s attempt to manually open S/C vent valve (air-operated valve).

Unsuccessful due to extremely high radiation.

Operator exposed to 100+ mSv (10+ rem.) (3/12 9:30)

AOV eventually opened by remote operation. (3/12 14:00)

Below Reactor

Core

Reactor Core


Accident Response at 1F<Preventing Core Damage of Units-5/6>

PCV

RHR System

Recirculation

Pump

R/B

RHR Pump

RHR

Heat

Exchanger

RPV

MPower supplied from D/G-6B

using temporary cable.

M

Sea

Damaged

by Tsunami

P

Sea

Underwater Pump

Temporary

Power Source

M/C

RHRS Pump Flooded by

Tsunami

� Ultimate heat sink restored on March 19th.

� Cold shutdown achieved on March 20th.

��Determination to save Units-5/6.Sea


Unit #3

Hx

Building

Unit #1

Reactor

Rad-Waste

Building

ERC

Main Office

Unit #4

Turbine

Unit #2

Hx

Building

Unit #1

Hx

Building

Unit #4

Hx

Building

Unit #2

ReactorUnit #3

Reactor

Unit #4

Reactor

Unit #3

Turbine

Unit #1

Turbine

Unit #2

Turbine

MobilePowerSupplyTruck (500kVA)

Temporary Cables

MobilePowerSupplyTruck (500kVA)

6.6kV/480VTransformer

6.6kV/480VTransformer

Accident Response at 2F<Temporary Power Supply and Motor Replacement>

• 9 km of cables laid by hand

and motors replaced to restore

ultimate heat sink.

• All 4 units brought to cold

shutdown.

��Many lessons to be learned

from success stories.


Overview of the 10-Unit Simultaneous Accidents

3/16-19

3/20

3/14

3/12

42 3642 1531

3/15

3/13

3/11

2F1FDate

3/14 17:00

3/14 1:24

RHR3/14 7:13

RHR

3/14 15:42

RHR

3/14 18:00

3/15 7:15

3/12 12:15

3/20 14:30

3/19 22:14

RHR

3/12 8:13

D/G-6B

3/22 10:35

P/C-4D

3/22 10:36

P/C-4D

3/20 15:46

P/C-2C

3/20 15:46

P/C-2C

3/19 5:00

RHR

3/20 14:30

Station Blackout

Loss of Ultimate Heat Sink

Cold Shutdown

3/12 15:36 Unit 1 Explosion

3/15 6:00-6:10 Unit 4 Explosion

3/14 11:01 Unit 3 Explosion

3/11 15:27 1st Tsunami, 15:35 2nd Tsunami 3/11 15:22~ Tsunamis

Water Injection: NO

Heat Removal: NO

Water Injection: YES

Heat Removal: NO

Water Injection: YES

Heat Removal: YES


0

20

40

60

80

100

120

140

160

180

200

3/11

3/12

3/13

3/14

3/15

3/16

3/17

3/18

3/19

3/20

3/21

3/22

3/23

3/24

3/25

0

50

100

150

200

250

300

350

400

450

500

Daily

Cumulative

Hundreds of Aftershocks Greater than M 5.0D

aily

Num

ber

of A

fters

hocks

Cum

ula

tive N

um

ber

of A

fters

hocks

On March 11th alone

179 times > M 5.0

38 times > M6.0

3 times > M7.0

cf. Earthquake in Virginia on

Aug. 23, 2011 was M 5.8

(Source) Japan Meteorological Agency


Voices from the Field

� “In an attempt to check the status of Unit 4 D/G, I was trapped inside the security gate compartment. Soon the tsunami came and I was minutes away from being drowned, when my colleague smash opened the window and saved my life.”

� “In total darkness, I could hear the unearthly sound of SRV dumping steam into the torus. I stepped on the torus to open the S/C spray valve, and my rubber boot melted.”

� “The radiation level in the main control room was increasing by 0.01 mSv (1 mrem) every 3 seconds but I couldn’t leave—I felt this was the end of my life.”

� “I asked for volunteers to manually open the vent valves. Young operators raised their hands as well.”

� “Unit 3 could explode anytime soon, but it was my turn to go to the main control room. I called my dad and asked him to take good care of my wife and kids should I die.”

D/G: Diesel GeneratorSRV: Safety Relief ValveS/C: Suppression Chamber

Unit 1 Main Control Room

Torus Room


Internal Investigation Committee Final Report

� Issued on June 20, 2012� Main body: 373 pages; Appendix: 567 pages

� Chapters

1. Purpose

2. Overview

3. Preparation for Earthquakes/Tsunamis

4. Securing Reactor Safety

5. Emergency Preparedness

6. Impact of Earthquake

7. Impact of Tsunami

8. Immediate Response at 1F Units 1-3

9. Response Related to SFPs

10.Support to Site

11.Explosion Evaluation for 1F Units 1, 3 and 4

12.Radioactivity Release Evaluation

13.Radiological Protection

14.Lessons Learned: “Tangible”

15.Lessons Learned: “Intangible”

16.Cause and Countermeasures

17.Conclusions


Lessons Learned and Countermeasures

“Tangible” Modifications

�Flood Protection�High-pressure Injection System

� RCIC, SLC, CRD

�Depressurization System� N2 Cylinders, Batteries

�Low-pressure Injection System� FP, MUWC

�Heat Removal/Cooling System� Containment venting, shutdown cooling, SFP cooling

�Power Supply for Instrumentation�Post-Core Damage Mitigation

� Hydrogen accumulation prevention, radioactivity release mitigation

�Common Items� Off-site power, rubble removal, communication system, lighting, RP, etc.

�Mid-to-Long Term Items� Reliable/filtered venting, post-accident instrumentation, reliable high-pressure

system, etc.


Lessons Learned and Countermeasures

“Intangible” Modifications

�Operational Measures in Relation to Tangible Modifications�Emergency Preparedness

� Organization, command and control� Long-term coping plan� Immediate response plan

� Information Dissemination and Sharing�Roles and Responsibilities� Information Disclosure�Transportation of Resources�Access Control�Radiological Protection�Plant Status Recognition�Suggestions to Japanese Government

� Off-site center, procurement, dose limit, external hazards criteria, tsunami data, low-dose radiation health effects


Immediate Safety Measures at Kashiwazaki-Kariwa NPS

Fire trucks to inject water into RPV and SFP

Transfer water from filtered/purified water tank to CST

Spare gas cylinders to depressurize PCV

Emergency Power - High voltage power trucks

- Portable generators

- Spare cables

Mobile power trucks

Spare sea water pumps

LegendFire protection sys.

Make-up water sys.RCIC

Power line

Fuel pool cooling sys.

Reactor Clean upWater sys.

Diesel driven fireprotection pumpStand by Liquid

Control System Pump

RCIC pump

Sea

Battery

MotorControl Center

Purified waterTransfer pump

Control Panel

Reactor Building

PCV

Charger

Spent Fuel Pool

RPV

Spare gas cylinder

Reactor Clean up pump

Fuel pool cooling pump

Make-up water pump

Heat Ex

SeaHeat Ex

※

※

※

※

Submergedpump

CondensateStorageTank

Fire Truck

Filtered waterTank

Purified waterTank

Containment Vent valveSpare gas cylinder

To Turbine

SRV

Low voltageDistribution PNL

Spare gas cylinders to depressurize RPV

• Revamped safety at TEPCO’s 7-unit nuclear power station.

• Issued 1,300+ page Phase 1 Stress Test Reports.


Further Safety Measures at Kashiwazaki-Kariwa NPS

Sea

Enforcement of power source(1)GT-driven generator truck(2)Emergency high voltage distribution panel(3)Cable from emergency high voltage panel for RHR

Enforcement of injection and heat removal- Submerged pump- Heat exchanger truck- Spare hose

Enforcement of injection and heat removal(2)Reservoir on site.

Others(1) Additional monitoring cars

(2) Additional warehouse for emergency materials on the hill

Prevention of accumulating Hydrogen(1)Top vent on Reactor Building

To RHRTo SFP

Turbine buildingReactor building

Heat exchange building

Off site power line

Filtered water tank

Filtered water tank & Purified water tank

Enforcement of protection for flooding(1)Embankment(2)Wall(3)Water-tight doors in Reactor Building


R/B

Wire Lever block

Reactor Building Top Vent at Kashiwazaki-Kariwa NPS

Newly-installed Top Vent enables

hydrogen gas to be vented from

reactor building by manual operation.


Current Status of 1F and Roadmap Towards Restoration

Unit 1 Reactor Building Cover

Achieved goals of Step 2 of Roadmap Towards Restoration on Dec. 16, 2011.

�Reactors achieved “cold shutdown condition”

�Sufficiently low radiation dose at the site boundary can be maintained


Current Status of 1F and Roadmap Towards Restoration (cont’d)

Accumulated Water Treatment Facilities

Contamination removed from accumulated water

and reused for reactor cooling.



Estimated radiation dose due to current release

1/50 of statutory limit at site boundary. (as of March, 2012)

Release Rate of Radioactive Cesium from Units 1-32011 2012



(Source) http://ramap.jaea.go.jp/map/map.html

1 μSv/h = 8.76 mSv/y

2.28 μSv/h = 20 mSv/y

Evacuation zones to be relaxed

for areas below 20 mSv/y.

1F

(Source) http://www.meti.go.jp/earthquake/nuclear/pdf/20120401map.pdf

Aerial Radiation Dose Map

(μSv/h at 1 m above ground; as of Feb. 2012)

Evacuation Zones(as of April 2012)

1F


Evaluation of Atmospheric Release of Radioactivity

Dose rate, plant parameter, meteorological data on March 15

Input data (meteorological, dose

rate, release point)

Calculate release rate

Allocate release rate among noble gas, I, Cs

Evaluate Cs deposition

Compare with other studies.

Compare with MEXT

survey

Evaluation Flow Using

DIANA Code


Evaluation of Atmospheric Release of Radioactivity (cont’d)

� Estimated release in INES scale:

900 PBq (cf. approx. 1/6 of Chernobyl)

� High-radiation zone in NW likely due

to direct release from Unit 2 R/B.

� Containment venting of Units 1-3 not

dominant contributor for total release.

Steam Released on March 15 at 10am

March 15 at 10am

Trajectory of Plume Released from Unit 2 R/B

March 15 at 8pm

Rain Cloud Observed on March 15 at 11pm

(Source) http://agora.ex.nii.ac.jp/earthquake/201103-eastjapan/weather/data/radar-20110311/

1F


Confirmation of Structural Integrity of 1F Unit 4 R/B

Non-destructive Inspection of Concrete

(Schmidt Hammer)

Visual Inspection of Cracks

Tilt Measurement


Confirmation of Structural Integrity of 1F Unit 4 R/B (cont’d)

� Structural integrity confirmed by tilt measurement, visual inspection,

non-destructive inspection.

� Seismic safety margin confirmed against design-basis seismic

ground motion by seismic response analysis and 3D-FEM analysis.

� Additional seismic margin (20%) added by reinforcement of SFP floor.

3D Finite Element Method Analysis

No credit taken for rigidity of slightly bulged outer wall (as well as of

damaged walls).

Reinforcement of SFP Floor


Mid- to Long-Term Road Map Towards

Decommissioning of 1F Units 1-4

Removal of Rubbles from Reactor Buildings

Phase-1 Phase-2 Phase-3

Begin removal of fuels from spent fuel pools

Completion of Step 2 Within 2 years Within 10 years 30 to 40 years

Begin removal of fuel debris

Complete decommissioning

Global collaboration

needed to work on

unprecedented R&D

undertaking.


Analysis of Core Damage Condition of 1F Units 1/2/3

� Fuels completely melted and relocated to bottom of RPV.� RPV breach likely occurred, leading to molten core-concrete

interaction at PCV pedestal floor.� Max. penetration depth of 0.65 m.

� Fuels damaged but significant damage to RPV leading to large amount of fuel dropping into PCV floor unlikely.

� If damaged fuel had to dropped into PCV floor, molten core-concrete interaction would have occurred .

� Max. penetration depth of 0.12 m (Unit 2) / 0.20 m (Unit 3).

Core-Concrete Interaction assumed to have stopped within

PCV steel plate; fuel debris currently cooled.

FDW

PCV

RPV

CS FDWCS

PCV

RPV

Unit 1 Units 2/3

7.6 m

2.6 m

7.6 m

2.6 m


Other Activities and Summary

TEPCO will continue to take every measure possible to:

�Maintain safe and stable condition of 1F;

�Mitigate suffering of afflicted people of Fukushima;

�Disseminate lessons learned from accident globally.

�Compensation for afflicted people:�1.01 trillion JPY (approx. $13 bn)

(paid out as of July 2012)

�Cooperation with gov’t in off-site radiation survey, decontamination work, etc.:�Approx. 1,420 man-days

(as of May 2012)

�Assistance in temporary return of evacuees to homes.


References

� TEPCO English websitehttp://www.tepco.co.jp/en/nu/fukushima-np/index-e.html

� TEPCO Fukushima Daiichi One-year Reviewhttp://www.tepco.co.jp/en/nu/fukushima-np/review/index-e.html

� TEPCO Internal Investigation Committee Interim Reporthttp://www.tepco.co.jp/en/press/corp-com/release/11120205-e.html

� Mid- to Long-Term Road Map Towards Decommissioning of 1F Units 1-4http://www.tepco.co.jp/en/press/corp-com/release/11122107-e.html

� NISA (Nuclear and Industrial Safety Agency) http://www.nisa.meti.go.jp/english/

� Government Investigation Committee Interim Reporthttp://icanps.go.jp/eng/interim-report.html

� JAIF (Japan Atomic Industrial Forum)http://www.jaif.or.jp/english/

� JANTI (Japan Nuclear Technology Institute)http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/report.pdf

� INPO (Institute of Nuclear Power Operations)—Special Report on Fukushima Daiichi NPShttp://www.nei.org/resourcesandstats/documentlibrary/safetyandsecurity/reports/special-report-on-the-nuclear-accident-at-the-fukushima-daiichi-nuclear-power-station

� EPRI (Electric Power Research Institute)—Fukushima Daini Independent Review and Walkdownhttp://my.epri.com/portal/server.pt?Abstract_id=000000000001023422

� NEI (Nuclear Energy Institute)—Article on Fukushima Dainihttp://safetyfirst.nei.org/safety-and-security/fukushima-daini-model-of-a-safe-shutdown/

� IAEA (Int’l Atomic Energy Agency)—Int’l Fact Finding Expert Mission of Fukushimahttp://www-pub.iaea.org/MTCD/Meetings/PDFplus/2011/cn200/documentation/cn200_Final-Fukushima-Mission_Report.pdf

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