comparison of i-131 releases fromthe fukushima and chernobylaccidents
TRANSCRIPT
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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
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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
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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
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Location of the Nuclear Installations
5
1-3. Nuclear reactors near epicenter of the earthquake
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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
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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)
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10
3. Accident progression & countermeasures
3A. Reactor related accident
3B. Accident at Spent Fuel Pools
3C .Leakage of radioactive water
3D. INES rating
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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
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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)
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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)
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[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
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[kPa] [mm]
17
Hydrogen
explosion
3A-6. Trend data of Unit1 until April21
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3A-7. Accident progression at Unit1(1/3)
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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
3A-7. Accident progression at Unit1(2/3)
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Accumulation ofHydrogen
Plaster
board
Reinforced
Concrete
Reactor building
Explosion
Reactor building
Hydrogen explosion in the operation floor
20
3A-7. Accident progression at Unit1(3/3)
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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
PCV Spray Cooling System
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)
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Feed water line
Fresh water injection
using feed water line
HPCI
PCV
Reactor Bldg.
RPVIsolation
Condenser
PCV Spray Cooling System
Core Spray System
Poison Tank
Condensate Storage
Tank: Inoperable
22
- Switched to fresh water injection on May 25th
Filtrate
Tank
Reservoir
tank
Pump
3A-8. Countermeasures at Unit1(2/3)
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- Nitrogen injection to the PCV (since April 6th)
23
Nitrogen injection tothe PCV to prevent
Hydrogen explosion
PCV
RPV
Temporary N2
Generator
3A-8. Countermeasures at Unit1(3/3)
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24
Unit 4Unit 3
Unit 2
3A-9. Accident Progression at Unit2 through 6
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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
3A-10. Chronology of Unit2 after the earthquake(2/4)
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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
3A-10. Chronology of Unit2 after the earthquake(3/4)
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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 )
3A-10. Chronology of Unit2 after the earthquake(4/4)
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[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
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[kPa] [mm]
30
Explosion sound near S/C
3A-12. Trend data of Unit2 until April21
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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.
3A-13. Chronology of Unit3 after the earthquake(1/3)
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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
3A-13. Chronology of Unit3 after the earthquake(2/3)
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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 )
3A-13. Chronology of Unit3 after the earthquake(3/3)
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[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
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[kPa] [mm]
35
Hydrogen
explosion
3A-15. Trend data of Unit 3 until April 21
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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
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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
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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
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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
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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)
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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
3B-3. Measures taken to cool the Spent Fuel Pool(2/3)
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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
3B-3. Measures taken to cool the Spent Fuel Pool(3/3)
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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
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-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
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45
Surge Tanks of
Suppression PoolWater
Condensate
Storage Tank
Turbine
Building
Condense
r
3C-2. Measures to remove the radioactive water
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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
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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
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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
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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
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4. Radiation Monitoring
51
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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
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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)
/
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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
4-2.On-site Monitoring (2/5)
( / )
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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)
4-2.On-site Monitoring (3/5)
i i i ( / )
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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.On-site Monitoring (4/5)
4 2 O i M i i (5/5)
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57
4-2.On-site Monitoring (5/5)
4 3 Off it M it i (1/5)
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58
-1 Radiation monitoring
4-3.Off-site Monitoring (1/5)
4 3 Off it M it i (2/5)
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59
32
approx. 30km from 1F
in northwest direction
33
approx. 30km from 1F
in northwest direction
31
approx. 30km from 1F in
west-northwest direction
34
approx. 30km from 1F
in northwest direction
-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-site Monitoring (2/5)
4 3 Off it M it i (3/5)
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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-site Monitoring (3/5)
4 3 Off it M it i (4/5)
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-1 Concentration of Radioactive Materials (Soil Samples)
61
4-3.Off-site Monitoring (4/5)
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62
5. Overview of Chernobyl accident
5 1 Chernobyl: review of incident
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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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64
Chernobyl
5-2. Chernobyl accident radiation levels /zones
5 3 Chernobyl accident atmospheric dose
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65
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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66
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!