The Fukushima DaiichiTomomi MatsunagaKansai Electric Power Company Cooperation With JEPIC (Japan an...

7/31/2019 The Fukushima DaiichiTomomi MatsunagaKansai Electric Power Company Cooperation With JEPIC (Japan an Electric Power Information Center)

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The Fukushima DaiichiThe Fukushima Daiichi

Nuclear Power Station AccidentNuclear Power Station Accident

Tomomi Matsunaga

Kansai Electric Power Company

Cooperation with JEPIC (Japan an Electric Power Information Center)


2/14

Number of units Total power (MW)

In operation

Under construction

Total

Nuclear Power Plants in Japan

Cessation of Operation : The Japan Atomic Power Co. Tokai (1998)

Chubu EP Co. Hamaoka-1,2 (2009)

2

1


3/14

Status of Nuclear Power Plants after the Earthquake

Source: Japan Atomic Industrial Forum, INC. (JAIF)

All units (Unit 1-3) were

immediately shut down

automatically

Then safely went into cold

shut down

The unit was immediately

shut down automatically

Then safely went into cold

shut down

3

The accident caused environmental damage at several

units in the Fukushima Daiichi nuclear power Station

after the earthquake occurred on March 11.

Other nuclear power plants in Japan were in normal

operation or safely shutdown.


4/14

The Fukushima Daiichi Nuclear Power Station

4

Before the earthquake

Unit6Unit5

Unit1

Unit2Unit3

Unit4


5/14

Source: NISA (http://nei.cashfly.net/static/images/BWR_illstration.jpeg)

Overview of Boiling Water Reactor (BWR)

(Mark-I Type ;Fukushima Daiichi Unit 1,2,3,4 and 5)

5


6/14

Mechanism of Boiling Water Reactor (BWR)

6

Containment VesselReactor PressureVessel

Condenser

Sea water

Pump

steam

waterGenerator

Turbine

Control rod

Suppression Chamber

fuel

Pump

Dry Well

Pump

Supply

Electricity

Electricity is generated by rotating the

turbine and the generator with steam.

Water is boiled within

the reactor.

Steam is generated and

sent to the turbine.


7/14

Source: The Tokyo Electric Power Company, Inc.

Before the earthquake ,Unit 1,2 and 3 of the Fukushima Daiichi Power plant were

operating .

Unit 4,5 and 6 were under periodic inspection.

After the earthquake , all control rods were inserted into the reactor as designed

and Unit 1,2 and 3 automatically shutdown .

Offsite power supply was lost because of the earthquake.

The emergency diesel generators installed in each Unit started normally.

Direct damage to the safety-related equipment due to the earthquake was not

found.

Seawater pumps, DGs, and power panels at all Units were flooded by the tsunami,then all AC power sources for Units 1 to 6,except for one air-cooled DG for Unit 6

lost their functionality.

All motor operated safety systems, water injection and cooling facilities at Units 1

to 5 became inoperable. This is the major cause of the Fukushima daiichi

accident.

Accident Description: Fukushima Daiichi NPS7


8/14

GeoEyeC

Intensive Inflow

inflow

inundated

Fukushima DaiichiFukushima Daiichi Fukushima DainiFukushima Daini

8

Inundated and Inflow Area at Fukushima Daiichi and Daini Site


9/14

Turbine Electrical

Generator

Condenser

Condensate

Storage Tank

Poison

TankStandby Liquid

Control System

Core Spray System

PCV Spray Cooling System

PCV

HPCI

RPV

Reactor Bldg.

Inoperable

since the

battery was

soaked in

water

Core Cooling by

Isolation Condenser

(3/11 14:52)

FeedwaterLine

Isolation

Condenser

Main Steam Line

Pump

Effort to sustain reactor water level

: Inoperable

: Operable

Accident progression at Unit1(1/3)

Source: Nuclear and Industrial Safety Agency (NISA)

9

Inoperable due to

the emergency

DGs soaked in

water (3/11 15:37)

External

electricity

was

inoperable

due to the

earthquake(3/11 14:46)


10/14

HPCIFunction has not been correct

Core Spray System

Poison Tank

TurbineElectrical

Generator

CondenserFeedw

aterLine

Main Steam Line

Pump

PCV

RPV

Reactor Bldg.

Isolation

Condenser

Condensate

Storage Tank

PCV Spray Cooling System

Decrease in reactor water level due to loss of cooling capability

of emergency condenser, followed by uncovering the core

: Inoperable

Uncovering the Core(3/11 around 17:00 estimated)

Decrease in reactor

water level

- Fuel Rod damage

-Hydrogen Generation

due to a Zirconium-

Water reaction

Accident progression at Unit1(2/3


10


11/14

Accumulation of

Hydrogen

Plaster

board

Reinforced

Concrete

Reactor building

Explosion

Reactor building

Hydrogen explosion in the operation floor


Accident progression at Unit1(3/3)11


12/14

Unit 4Unit 3

Unit 2

Accident Progression at Unit 2 through 4


12

Vapors rising from Unit 3 are assumed to be produced from Spent Fuel Pool.


13/14

RxW

ater

Leve

l[mm]

RCIC

HPCI No Operation

SRV

FP/Fire Engine

PCV Vent

Fuel Range (A) (mm)

Fuel Range (B) (mm)

CAMS D/W(A)(Sv/

CAMS S/C(A)(Sv/

S/C Pressure (MPa)

D/W Pressure (MPa)

19:Sea Water

Order for Vent Preparation

17:30

Depressurization~18:00

Earthquake14:46 Tusnami

15:27

(2:55) Operation confirmed

(11:00

Vent Line

Configuration Completed

Unit1 R/BExplosion15:36

Core Damage Started due toMAAP Analysis

R

xPressure

[

MPa]

D/W

&S/C

Pressure[MPa]

Fukushima Daiichi Unit 2 Plant Parameter and OperationUnit3 R/BExplosion11:01

Impact sound6:00-6:10

Valve Condition Unclear

Order for Sea Water InjectionPreparation 12:05

2Valves Open

Small Vent Valves Opened

(13:25)Out of Service Judged

0(TAF)

13

Source: The Tokyo Electric Power Company, Inc.

Rx Pressure (A) (MPa)

Rx Pressure (B) (MPa)

Hydrogengeneration

Increase inD/W pressure

S/C pressure:0Mpa

Decrease inD/W pressure

Radioactivegas

released

into the air


14/14

Plant Parameter: Fukushima Daiichi Unit 2

Source: NISA and JNES

March 11 March 30, 2011

14

Increase in D/Wpressure

Decrease inD/W pressure

around 11:30around 15:00

Radioactivegas

released

into the air

Date post:	05-Apr-2018
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