comparison of i-131 releases fromthe fukushima and chernobylaccidents

7/31/2019 Comparison of I-131 Releases Fromthe Fukushima and Chernobylaccidents

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Comparison of I-131 releases fromthe Fukushima and Chernobyl

accidents

David W. Miller, Ph.D. University of Illinois/NATC

Jason T. Harris, Ph.D., S. Neil Flegel, Justin Jensen Idaho

State University


2/73

Contents

1. Outline of earthquake and nuclear reactors ------------------3

2. Outline of Fukushima Dai-ichi NPS ------------------------------7

3. Accident progression & countermeasures -------------------10

4. Radiation monitoring -------------------------------------------------51

5. Overview of Chernobyl accident ----------------------------------626. Comparison of I-131 releases from both accidents---------66

7. Closing Remarks ----------------------------------------------------------------71

2


3/73

Epicenter

Occurred 14:46 March 11, 2011

Magnitude:9.0 Mw

Epicenter location: 38 6N and

142 51E, and 24km in depthIt is said that the height of tsunami

attacked Fukushima NPP was more

than 14m

Fukushima Dai-ni NPP

Source: www.tepco.co.jp

Fukushima Dai-ichi NPP

Source: www.tepco.co.jp

1-1. 2011 off Tohoku Pacific Earthquake

3


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4

East coast of northern area in the main island of Japan is seriously damaged

As of April 18, 13,802 people are dead and 14,129 people are missing

4

Source: Fire and Disaster Management Agency

1-2. Tsunami after the earthquake


5/73

Location of the Nuclear Installations

5

1-3. Nuclear reactors near epicenter of the earthquake


6/73

11 reactors were automatically shut-down- Onagawa Unit 1,2,3

- Fukushima Dai-ichi (I) Unit 1,2,3

- Fukushima-Dai-ni (II) Unit 1,2,3,4

- Tokai Dai-ni (II)

3 reactors were under periodic inspection

- Fukushima Dai-ichi (I) Unit 4,5,6

-After the automatic shut-down, the Unit 1-3 at OnagawaNuclear Power Station, the Unit 3 at Fukushima II NuclearPower Station, and the Unit at Tokai II Nuclear Power Stationhave been cold shut down safely.

-As for the unit 1,2,4 at Fukushima II Nuclear Power Station,the operator of the station reported NISA nuclear emergencysituation because the temperature of the suppression poolsbecame more than 100 , but afterward the three units havebeen cold shut down.

6

1-4. Automatic shut-down of nuclear reactors


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7

2. Outline of Fukushima Dai-ichi NPP


8/73

Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6

BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5

PCV Model Mark-1 Mark-1 Mark-1 Mark-1 Mark-1 Mark-2

Electric Output (MWe) 460 784 784 784 784 1100

Max. pressure of RPV 8.24MPa 8.24MPa 8.24MPa 8.24MPa 8.62MPa 8.62MPa

Max. Temp of the RPV 300 300 300 300 302 302

Max. Pressure of the CV 0.43MPa 0.38MPa 0.38MPa 0.38MPa 0.38MPa 0.28MPa

Max. Temp of the CV 140 140 140 140 138 171(D/W)

105(S/C)

Commercial Operation 1971,3 1974,7 1976,3 1978,10 1978,4 1979,10

Emergency DG 2 2 2 2 2 3*

Electric Grid 275kV4 500kV2Plant Status on Mar. 11 In

Operation

In

Operation

In

Operation

Refueling

Outage

Refueling

Outage

Refueling

Outage

* One Emergency DG is Air-Cooled

8Source: Application document of license for establishment of NPP

2-1. Summary of Fukushima Dai-ichi NPP


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9

Reactor

Building

Containment Vessel

Dry Well

Spent Fuel Pool

Reactor Pressure

Vessel

Suppression Chamber

2-2. Overview of Mark-1 Type BWR (Unit 1,2,3 and 4)


10/73

10

3. Accident progression & countermeasures

3A. Reactor related accident

3B. Accident at Spent Fuel Pools

3C .Leakage of radioactive water

3D. INES rating


11/73

Source: Google Earth

Many structures

facing the bay are

destroyed

Before the earthquake

After the earthquake (before explosion)

11

3A-1. Satellite view of Fukushima Dai-ichi NPP)


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1

Seawater Pump

Elevation:about 10m

TurbineBuilding

Station Black Out

Tsunami (estimated more than 10m)

Grid Line

D/G Inoperable due to Tsunami flood

D/G

Seawater level

Loss of offsite powerdue to the earthquake

All Motor Operated pumps (including ECCSpumps) became i noperable

Reactor

Building

12

Note:

-All operating units when earthquake

occurred were automatically shut

down.-Emergency D/Gs have worked

properly until the Tsunami attack.

3A-2. Major root cause of the damage


13/73

Unit 1

13

3A-3. Accident Progression at Unit 1 Reactor


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11th Under operation, Automatic shutdown by the earthquakeLoss of A/C power

Loss of water injection function

12th Unusual increase of PCV pressureStarted to vent

Sound of explosion

Started of injection of seawater and borated water to the core

22nd

Rise of reactor temperature (383

) Drop (26th 05:00 144.3

)

23rd Water supply line in addition to the Fire Extinguish line. Switched to watersupply line only.(Flow rate: 7m3/h)

24th Lighting in the Central Control Room was recovered.

25th Started fresh water injection

29th Switched to the water injection to the core using a temporarymotor operated pump.

31st Started to transfer the stagnant water from the Condensate StorageTank(CST) to the Surge Tank of Suppression Pool Water(SPT) 14

Unit 1

3A-4. Chronology of Unit 1 after the earthquake(1/2)


15/73

15

Unit 1(Continued)

Apri

l

3rd

The power supply to the temporary motor-driven pump was switched

from

the temporary power supply to the external power supply

Started to transfer the water from the Condenser to CST

6th Started the operation for the injection of nitrogen to PCV

9th Started the using highly pure nitrogen generator in the injection of

nitrogen to PCV

10th Completed transferring the water from the Condenser to CST

11th Loss of external supply due to an earthquake occurred and water injection

to the Reactor core and nitrogen injection to PCV were

suspended. Resumed.

17th Confirmed the situation in the reactor building using an unmanned robot

18th

Stopped the water injection into the reactor core to replace the currenthose with a new one.

19th Completed the work of strengthening connection of the power suplies

between Unit 1-2 and Unit3-4.

Fresh water is being injected to the spent fuel pool and the reactor(As of April 22nd )

3A-4. Chronology of Unit 1 after the earthquake(2/2)


16/73

[kPa] [mm]

3/11 14:46

Reactor Shut Down

3/11 15:42

Station Black out

Loss of ECCS

function

Radiation

levelincrease at

turbine bldg.

Hydrogen

explosion

Start S/C Venting

operation

Sea water injection

via fire extinguish line

Increase in CV

pressure.

Reported High

radiation level

16

3A-5. Trend data of Unit1 until March15


17/73

[kPa] [mm]

17

Hydrogen

explosion

3A-6. Trend data of Unit1 until April21


18/73

3A-7. Accident progression at Unit1(1/3)


19/73

HPCIFunction has not beencorrect

Core Spray System

Poison Tank

TurbineElectricalG

enerator

CondenserFeedwaterLine

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

Decrease in reactor

water level

-Possible Fuel Rod

damage

-Hydrogen Generation due

to the Zirconium- Water

reaction

19



20/73

Accumulation ofHydrogen

Plaster

board

Reinforced

Concrete

Reactor building

Explosion

Reactor building

Hydrogen explosion in the operation floor

20



21/73

Sea

Fire pump

Fire extinguishing

basin

Sea water injection to theRPV from the existing

makeup water system using

fire-extinguishing pump

HPCI

PCV

Reactor Bldg.

RPVIsolation

Condenser

Fire pump


Core Spray System

Poison Tank

Condensate

Storage Tank

- Sea water injection using fire water pump -

S/C Venting to depressurize the PCV

: Inoperable

Stack

SGTS

S/C Venting to

depressurize the PCV

21

3A-8. Countermeasures at Unit1(1/3)


22/73

Feed water line

Fresh water injection

using feed water line

HPCI

PCV

Reactor Bldg.

RPVIsolation

Condenser


Core Spray System

Poison Tank

Condensate Storage

Tank: Inoperable

22

- Switched to fresh water injection on May 25th

Filtrate

Tank

Reservoir

tank

Pump



23/73

- Nitrogen injection to the PCV (since April 6th)

23

Nitrogen injection tothe PCV to prevent

Hydrogen explosion

PCV

RPV

Temporary N2

Generator



24/73

24

Unit 4Unit 3

Unit 2

3A-9. Accident Progression at Unit2 through 6


25/73

25

11th Under operation, Automatic shutdown by the earthquake

Loss of A/C power

Loss of water injection function

14th Loss of water cooling function

Unusual increase in PCV pressure

15th Sound of explosion

Possible damage of the suppression chamber20th Injection of about 40 tons of seawater into SFP through fire

extinguishing

system.

Injection of seawater to the Spent Fuel Pool (SFP)

21st White smoke generated

22nd Injection of seawater to the Spent Fuel Pool (SFP)

25th Injection of seawater to SFP

Unit 2

3A-10. Chronology of Unit2 after the earthquake(1/4)


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26

Unit 2(Continued)

26th Lighting in the Central Control Room was recovered

27th Switched to the water injection to the core using a temporary motor-driven

pump.

29th The Seawater injection to the Spent Fuel Pool using the Fire Pump

Truck was switched to the fresh water injection using the temporary

motor-driven pump

In order to prepare for transferring the stagnant water on the basement

floor of turbine building to the Condenser, the water in the Condensate

Storage Tank is being transferred to the Surge Tank of Suppression

Pool Water.

30th The injection pump was switched to the Fire Pump Truck. However,

because

cracks were confirmed in the hose (12:47 and 13:10 March 30th), the

injection was suspended. The injection of fresh water resumed at 19:05March 30th.

31st White smoke was confirmed to generate continuously.

Fresh water is being injected to the spent fuel pool and the RPV



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27

Unit 2(Continued)

April

1stFreshwater injection to SFP via FPC using temporary motor-driven pump

2nd The water, of which the dose rate was at the level of more than

1,000mSv/h ,was confirmed to be collected in the pit located near the intake

Channel of Unit2.

Started to transfer the water from the condenser to the CST

3rd The power supply to the temporary motor-driven pump was switched from

the temporary power supply to the external power supply.

4th Freshwater injection to SFP via FPC using the temporary motor-driven

pump.

5th

9th

11th

12th

13th

Tracer is confirmed to outflow through the permeable layer around the pit

into the sea.

Completed transferring the water form the Condenser to CST.

Loss of external supply was suspended. Resumed

Transfer from the trench of the turbine building to the Condenser

Suspended the transfer for checking leaks, etc

Freshwater injection to SFP via FPC using the temporary motor-driven

pump



28/73

28

Unit 2(Continued)

18th Confirmed the situation in the reactor building using unmanned

robot

Stopped the water injection into the reactor core to replace the

current hose with a new one.

Injected coagulant(soluble glass) into the power cable trench

19th Started transfer the stagnant water with high-level radioactivity

from the trench of the turbine building to the buildings of

radioactive water treatment facilities

Completed the work of strengthening connection of the power

supplies between Unit1-2 and Units3-4

Injected freshwater to SFP via FPC using the temporary motor-

driven pump

Fresh water is being injected to the spent fuel pool and the reactor

(As of April 22nd )



29/73

[kPa] [mm]

RCIC start up

Sea waterinjection

3/11 14:46

Reactor Shut Down

3/11 15:42Station Black out

Explosion sound

near S/C

RCIC was lost

SRV Open

29

3A-11. Trend data of Unit2 until March17


30/73

[kPa] [mm]

30

Explosion sound near S/C

3A-12. Trend data of Unit2 until April21


31/73

31

Unit 3

11

th Under operation, Automatic shutdown by the earthquake Loss of A/C power

13th Loss of water injection function Started to vent

14th Unusual increase in PCV pressure

Sound of explosion

16th White smoke generated

17th Water discharge by the helicopters of Self-Defense Force(4 times)Water spray from the ground by High pressure water-cannontrucks (Police: once, Self-Defense Force: 5 times)

18th Water spray from the ground by same trucks (Self-Defense Force:6 times) Water spray from the ground by US water-cannon trucks(US armed force:1 time)

19th Water spray from the ground by High pressure water-cannontrucks by Hyper Rescue Unit of Tokyo Fire Department.



32/73

Unit 3(Continued)20th Sprayed by Hyper Rescue Unit of Tokyo Fire Department

22nd Lighting in the Central Control Room was recovered.

23rd Injection of seawater to the SFP

24th Injection of seawater to the SFP

25th Water spray (Emergency fire support team

Started fresh water injection

27th Water spray by Concrete Pump Truck

28th Switched to the water injection to the core using a temporary

motor-driven pump

In order to prepare for transfer the stagnant water on the basement

floor

of turbine building to the Condenser, the water in the Condensate

StorageTank is being transferred to the Surge Tank of Suppression Pool Water

April 3rd The power supply to the temporary motor-driven pump was

switched from the temporary power supply to the external power

supply.32



33/73

Unit 3(Continued)17th Confirmed the situation in the reactor building using unmanned

robot.

18th Stopped the water injection into the reactor core to replace the

current hose with a new one

19th Completed the work of strengthening connection of the power

supplies between Units1-2 and Units3-4

33

Fresh water is being injected to the spent fuel pool and the reactor

(As of April 22nd )



34/73

[kPa] [mm]

3/11 14:46

Reactor Shut Down

3/11 15:42Station Black out

Sea waterinjection

Hydrogen

explosion

Core cooling by

RCIC & HPCI

HPCI was lost

RCIC inoperable

S/C Venting

S/C

Venting

34

3A-14. Trend data of Unit 3 until March 17


35/73

[kPa] [mm]

35

Hydrogen

explosion

3A-15. Trend data of Unit 3 until April 21


36/73

Unit 4

36

14th Water temperature in the Spent Fuel Pool, 84

15th Damage of wall in the 4th floor confirmedFire occurred in the 3rd floor (12:25 extinguished)

16th Fire occurred. TEPCO couldnt confirm any fire on the ground.

20th Water spray over the spent fuel pool by Self Defense Force

21st Water spray over the spent fuel pool by Self Defense Force

22nd

-24th

Water spray (Concrete Pump Track (3 times)

25th Injection of seawater to SFP via the Fuel Pool Cooling Line (FPC)

Water spray (Concrete Pump Truck)

27th Water spray (Concrete Pump Truck)

29th Lighting in the Central Control Room was recovered.

April 12th

19th

Sampled the water in SFP

Completed the work of strengthening connection of the power

supplies between Units1-2 and Units3-4

No fuel is in the reactor. Fresh water is being injected to the spent fuel pool (As of April 22nd )

3A-16. Chronology of Unit4 after the earthquake


37/73

37

Unit 5&6

20th Unit 5 under cold shutdown (Water temperature of reactor water is less

than 100 )

Unit 6 under cold shutdown (Water temperature of reactor water is less

than 100 )

21st Water spray over the Common Spent Fuel Pool started

22nd Recovering power supply of unit 5 and 6 is completed.

24th The power was started to be supplied. Cooling also started

30th

April

4th

19th

20th

Bach up power of Unit 6 is in working condition and external power was

supplied to Unit 5 as of March 30th

Discharged the ground water with low-level radioactivity in the Sub Drain

Pit to the sea(Unit5 and 6)

Transferred stagnant water under the base of the turbine building to the

condenser for measuring the amount it.(Unit6)

The pump for RHR was temporarily stopped in order to change the positionof the hose of temporary RHR Seawater System.

Unit5 & 6 is under cold shut down(As of April 22nd )

3A-17. Chronology of Unit 5&6 after the earthquake


38/73

PCV

RPV

Reactor Bldg.

Spent FuelPool

Reactor Building

Closed Cooling Water

System

Fuel PoolCooling(FPC)

pump

Explosion

Uncovering the spent fuel

Possible concern:

-Hydrogen generation

-Fuel rod damage

Decrease in spent fuel pool

water level

Lack of cooling

capability

38

3B-1. Possible concerns about Spent Fuel Pool


39/73

Unit 1 2 3 4 5 6

Number of Fuel Assembly in theCore 400 548 548 - 548 764

Number of Spent Fuel Assemblyin the Spent Fuel Pool

292 587 514 1,331 946 876

Number of New Fuel Assemblyin the Spent Fuel Pool

100 28 52 204 48 64

Water Volume (m3) 1,020 1,425 1,425 1,425 1,425 1,497

Condition of the fuel in the Spent Fuel Pool

39

3B-2. Status of the Fuel as of March11, 2011


40/73

Unit 2

Spent Fuel

Pool (SFP)

Filtrate

Tank

Reservoir

tank

Pump

Dam

Unit 1

Water spray

using concrete

pump truck

Fresh water injection

40

Reservoir

tank

Sea waterFire Engine Pump

Fuel Pool

Cooling Line

SFP

SFP

1st Stage Sea water injection

2nd Stage Fresh water injection

Filtrate

Tank

Pump

Dam

3B-3. Measures taken to cool the Spent Fuel Pool(1/3)


41/73

Unit 3

Water spray

using concrete

pump truck

Filtrate

Tank

Reservoi

r tank

Pump

Dam

SFP

2nd Stage Fresh water injection

41

Sea water

Fresh water

in Fire engine

SFP

Fire Engine

Pump

Fuel Pool

Cooling Line

Water Sprayby

-Self-Defense Force

-Fire Department

-Police

1st Stage Sea water injection

Discharge of

Sea water-Self-Defense

Force



42/73

Unit 4

42

Note: Sampling of SFP water

DetectedNuclides Half life Density(Bq/cm3)

Cesium 134 Approx. 2 Years 88

Cesium 137 Approx. 30 Years 93

Iodine 131 Approx. 8 Days 220

Analysis result of water in the SFP of Unit 4

(Date of Collection 4/12)

Sea water

SFP

Filtrate Tank

Reservoir

tank

PumpDam

SFPWater Spray from the

ground by Self

Defense Force andFire Department

Water spray

using concretepump truck

1st Stage Sea water injection 2nd Stage Fresh water injection

-Cause of reactor building

damage to be investigated

continuously



43/73

3/19 05:00Start Unit 5 SFP

cooling by RHR

pump

3/19 22:14

Start Unit 6 SFP cooling byRHR pump

3/24 18:05

Start Common SFP cooling

Possible malfunction of

Thermometer

(Evaluated 3/24 6:35)

Measured from corrected water

3B-4. Temperature trend of Spent Fuel Pool


44/73

-Highly radioactive water was found in turbine building

and trenches at Unit1, 2 and 3

44

Reactor Building Turbine

Building

Side view of the Fukushima trenches (Source: Wikipedia)

Trench

3C-1. Water leakage in turbine buildings and trenches


45/73

45

Surge Tanks of

Suppression PoolWater

Condensate

Storage Tank

Turbine

Building

Condense

r

3C-2. Measures to remove the radioactive water


46/73

46

-Extremely highly radioactive water in the turbine building of Unit 2 has beentransferred to the radiation waste treatment building.

-To execute this operation, radioactive water originally stored radiation waste

treatment building and was discharged into the sea. (Total Quantity of

radioactivity : 0.15 tera Bq)

Reactor

Bldg.

Unit 1

Reactor

Bldg.

Unit 2

Reactor

Bldg.

Unit 3

Reactor

Bldg.

Unit 4

Turbine Bldg.

Unit1

Turbine Bldg.

Unit1

Turbine Bldg.

Unit 2

Turbine Bldg.

Unit 1

RadiationWaste

Treatment

Bldg.

#2 Trench

Transfer line using pressureresistant hose was laid within

the building to minimize the

leakage risk

Installation of

Water level gauge

3C-3. Transferring radioactive water to the radiation waste bldg


47/73


48/73

48

Large-sized Sandbags (finished on Apr.17)

Silt fence (Finished on Apr.14)

Steel plate insulation (Finished on Apr.15)

Sandbags containing Zeolite (in operation)

Sheet Pileunder planning)

Sliding timber weir (under planning)

Unit 1

Intentional discharge

of radioactive water(asof April4)

(from sub-drain of Unit

5&6)

I-131 20 Bq/cm3

Cs-134 4.7 Bq/cm3

Cs-137 4.9 Bq/cm3

analysis result of Unit 6

water

Leakage of Highly

radioactive water(as of

April12)

I-131 5.4106 Bq/cm3

Cs-134 1.8106 Bq/cm3

Cs-137 1.8106 Bq/cm3

Intentional discharge of

radioactive water(as of

Marh28)

(from radiation Waste

treatment building)

I-131 6.3 Bq/cm3

Cs-134 4.4 Bq/cm3

Cs-137 4.4 Bq/cm3

Unit 2 Unit 3 Unit 4

Strengthing the monitoring(please refer to page 87)

3C-5. Measures to prevent the spread of radioactive water


49/73

49

NISA issued provisional INES ratings , based on What is known at the

time.

At first, following units were rated as Level 3 based on Defense inDepth criteria about 10 hours later from the earthquake.

- Fukushima dai-ichi unit 1, 2 and 3, Fukushima dai-ni Unit 1, 2 and 4

In the evening on March 12, the rating of Fukushima dai-ichi Unit 1

was re-evaluated to Level 4 base on the Radiological Barriers and

Control criteria.

On March 18, Fukushima dai-ichi Unit 1, 2 and 3 were re-rated to Level

5 based on Radiological Barriers and Control criteria because the

fuel damage was highly possible. Fukushima dai-ichi Unit 4 was

evaluated to Level 3 based on the Defense in Depth criteria.

On April 12, Fukushima Dai-ichi NPP was revised Level 7 based on the

People and Environment criteria, as a result of dischargedestimation.

Official rating will be done after cause and countermeasures are

identified.

3D-1. INES Rating


50/73

Assumed amount of the dischargefrom Fukushima Dai-ichi

(Reference)

Amount of the

discharged from

the Chernobyl

accident

NISAs estimation*1

NSCs

estimation*2

131I(a) 1.3*1017Bq 1.5*1017Bq 1.8*1018Bq

137Cs 6.1*1015Bq 1.2*1016Bq 8.5*1016Bq

(Converted value to 131I)*3

(b)2.4*1017Bq 4.8*1017Bq 3.4*1018Bq

(a)+(b) 3.7*1017Bq 6.3*1017Bq 5.2*1018Bq

(notes)

*1: Estimation by NISA is based on the numerical analysis of accident transient*2: NSC calculated backward of monitoring data to estimate the amount of discharge

*3: multiplication factor of radiological equivalence to 131I is 40

3D-2. Bases of rating at Level7


51/73

4. Radiation Monitoring

51


52/73

Land

air dose ratemonitoring pointNo of monitoring points:65

air dose rate(monitoring car)

Integrated doseNo of monitoring points: 15

Sampling datadust, land soil and plants)No of monitoring points;

- dust:27

- land soil:53

- plants:17

Dose rate measurement at schools

No of monitoring points:1637

Foods and Drinks

Drinking waterfoodsradioactivity

Air sampling by airplane

air dose rate

Note:

Each prefecturehave been

correcting the following

paramater;

-Air dose rate

- Air borne monitoring

- Drinking water

On site

air dose rate and dust sampling

radioactivity in land soil

Sea

Radioactivity concentrationunder seaAir dose rate over

the sea (10-30km off the

shore

Around discharge point and 15kmoff the shore

4-1. Overview of radiation monitoring around the Fukushima-Daiichi NPP

Fukushima Dai-ichi NPP

Fukushima Dai-Ni NPP


53/73

Registered 11930Sv/h around Front Gate on March 15.

53

1F Monitoring Trend

Near Gym (East of MP-5)

Near West Gate (Near MP-5)

North of Admin. Bldg.

Front of Seismic Isolated Bldg

South of Admin. Bldg.

Date/time

AirDoseRate(Sv/h)

Near MP-4

Near Front Gate

Main Gate

West Gate

4-2.On-site Monitoring (1/5)

/


54/73

54

TEPCO conducted nuclide analyses of radioactive materials contained in the air which

were collected at the site of Fukushima Daiichi NPS.

Radioactive materials in the air


( / )


55/73

55

Detected densities of Pu-238. 239. and Pu-240 are the same IeveI as those of the

measured fallouts in Japan in the cases of previous nuclear tests in the atmosphere.

Since densities of Pu-238 detected in the playground and in area adjacent to industrial

waste disposal facility on April 11th can be considered to be caused by the nuclear accident

of this time.

Concentration of Radioactive Materials (Soil Samples)


i i i ( / )


56/73

56

In order to verify any leakages to underground and sea, and safety, TEPCO have been

implementing the sampling survey of subsurface water and seawater.


4 2 O i M i i (5/5)


57/73

57


4 3 Off it M it i (1/5)


58/73

58

-1 Radiation monitoring

4-3.Off-site Monitoring (1/5)

4 3 Off it M it i (2/5)


59/73

59

32

approx. 30km from 1F

in northwest direction

33



31

approx. 30km from 1F in

west-northwest direction

34



-2 Radiation monitoringOverall radiation level trending down since March 17th.

The highest value recorded at Monitoring Point #32 has peaked out at approx. 170Sv/h

and has been declining since, rendering no immediate health hazard.


4 3 Off it M it i (3/5)


60/73

60

Radiation level cumulatively measured since March 23th topped 19,470Sv at #32,

approximately 30km North West from 1F.

Cumulative Doses Measured


4 3 Off it M it i (4/5)


61/73

-1 Concentration of Radioactive Materials (Soil Samples)

61



62/73

62

5. Overview of Chernobyl accident

5 1 Chernobyl: review of incident


63/73

63

On 26 April 1986, at 01:23, reactor four suffereda catastrophic power increase, leading toexplosions in its core.

This dispersed large quantities of radioactive fueland core materials into the atmosphere and

ignited the combustible graphite moderator.

The burning graphite moderator increased theemission of radioactive particles, carried by the

smoke, as the reactor had not been encased by

any kind of hard containment vessel.

The accident occurred during an experiment

scheduled to test a potential safety emergencycore cooling feature, which took place during the

normal shutdown procedure.

5-1. Chernobyl: review of incident

5 2 Chernobyl accident radiation levels /zones


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Chernobyl

5-2. Chernobyl accident radiation levels /zones

5 3 Chernobyl accident atmospheric dose


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5-3. Chernobyl accident atmospheric dose

Contributions of the various isotopes to the (atmospheric) dose inthe contaminated area soon after the accident.


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6. Comparison of I-131 releases from Fukushima

and Chernobyl accidents

6 1 measurements in North America from Fukushima by date


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6-1. measurements in North America from Fukushima by date

0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-01

1.20E-01

1.40E-01

03/13/07 03/15/07 03/17/07 03/19/07 03/21/07 03/23/07 03/25/07 03/27/07 03/29/07 03/31/07

Concentration(pCi/m3)

Date Accident occurred March 11, 2011

I-131 in North America from Fukushima

The data was collected from a number of sites around the U.S., andincludes mixed medium.

Measurements from multiple locations at a nuclear facility were

averaged to one daily mean from that site.

6-2 measurements in North America from Chernobyl by date


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6-2. measurements in North America from Chernobyl by date

0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

1.40E+00

1.60E+00

04/29/82 05/09/82 05/19/82 05/29/82 06/08/82 06/18/82 06/28/82 07/08/82

Concentration(pCi/m3)

Date Accident occurred April 26, 1986

I-131 in North America from CHERNOBYL

The data was collected from a number of sites around the U.S., andincludes mixed medium.

Measurements from multiple locations at a nuclear facility were

averaged to one daily mean from that site.

6-3 Comparing I-131 levels on timeline scale


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6-3. Comparing I-131 levels on timeline scale

0.00E+00

2.00E-02

4.00E-02

6.00E-02

8.00E-02

1.00E-01

1.20E-01

1.40E-01

0 5 10 15 20 25

I-131concentration(p

Ci/m3)

Days since incident

I-131 from Fukushima

0.00E+00

2.00E-014.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

1.40E+00

1.60E+00

0 10 20 30 40 50 60 70

I-131concentration(pCi/m3)

Days since incident

I-131 from Chernobyl

6-4 Overlay of Chernobyl and Fukushima I-131 levels


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6 4. Overlay of Chernobyl and Fukushima I 131 levels

0.00E+00

2.00E-01

4.00E-01

6.00E-01

8.00E-01

1.00E+00

1.20E+00

1.40E+00

1.60E+00

0 10 20 30 40 50 60 70

I-131concentr

ation(pCi/m3)

Days since incident

Comparison of I-131 from Chernobyl and Fukushima

JAPAN

CHERNOBYL


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Closing Remarks:

The Fukushima accident is still ongoing and local radiation levelsand releases are still being evaluated

Preliminary I-131 levels (from 12 US NPP sites) are nearly an orderof magnitude less then what was seen from Chernobyl

The bimodal release from Chernobyl is not seen from this data

A more comprehensive study of the Fukushima releases iscurrently underway. Data is being compiled from all of the US NPPs

(with your help!) and the EPA RadNet locations.

Specifically:Study on I-131 gaseous vs. particulate fractionStudy on I-131/Cs-137 ratios

Geographical comparisons (plume movement)


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Acknowledgements

Dr. Wataru MizumachiNuclear and Industrial Safety Agency (NISA)

Japan Nuclear Energy Safety Organization (JNES)


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Questions?

Thank you!

comparison of i-131 releases fromthe fukushima and chernobylaccidents

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