Current Status of
Fukushima DaiDai-Ichi NPS

September 17
17，2012
2012
Tokyo Electric Power Company

Side Event by Government of Japan
at 56th IAEA General Conference, Sep 17, 2012©2012 The Tokyo Electric Power Company, INC. All Rights Reserved.

Contents【１】Core Cooling and Spent Fuel Pool Cooling【２】Mitigation of the Release of Radioactive Materials【３】Accumulated Water Processing【４】 Preventing the Spread of Contamination to the Ocean【５】 Countermeasures to reduce radiation dose at the siteboundaries due to rubble, etc【６】 Fuel Removal from Spent Fuel Pools【７】Countermeasures against Aftershocks and Tsunami【８】 Integrity Confirmation of Unit 4 Reactor Building【９】 Approach for monitoring the reactors and removing
fuel debris

11【１】Core Cooling ～ Circulating Water Cooling System ～Injected Cooling water is leaking from RPV, PCV and R/B to T/B.
Accumulated water in T/B is re-used as coolant after Cs and salt removal.
Components of RPV injection system have redundancy, diversity and independency.
A chiller has been installed into the RPV injection system to decrease temperature andamount of core injection water. (operation started:Jul.18,2012)

Spent Fuel Pool

Containment Vessel (PCV)
Pressure Vessel (RPV)

Reactor
Building(R/B)

TurbineBuilding(T/B)

Buffer Tank
Rad-waste Building

Cooling Water

Cs & Salt Removal: Leakage

chiller: In-flow of Ground Water

N2 Generator

2

Cold Shutdown Conditions【１】Cold
Circulating water cooling continued since June 27, 2011
The temperatures at the RPV bottom and inside PCV were approx. 35 ℃ -55℃ (as of
Sep.5,2012).
There is no significant fluctuation in parameters such as PCV internal pressure and amountof radioactive material releases from the containment vessel.
Thus it is determined overall that cold shutdown conditions are being maintained.

℃
200

200 ℃

150

150

Unit-2
100

100

Unit-150

0
7/17

Unit-1

Unit-3
50

9/26

12/6

2/15

4/26

RPV bottom temperature

7/6

0
9/15 7/17

Unit-2
Unit-3

9/26

12/6

2/15

4/26

7/6

9/15

Temperature in PCV

32

Spent Fuel Pool (SFP) Cooling【１】Spent
Closed loop with heat exchanger has been established for SFP of Unit 1~4.
Corrosion mitigation techniques are applied.
- Deoxidation by N2 and Hydrazine- Salt Removal (originated from sea water injection)

Spent Fuel Pool

Containment Vessel (PCV)
Pressure Vessel (RPV)
TurbineBuilding (T/B)

Reactor
Building
(R/B)

Heat
Exchanger

Desalinating

Hydrazine
Injector
Cooling Water: Leakage

Buffer Tank

N2 Generator

4【２２】Mitigation of the Release of Radioactive Materials
Spraying dust inhibitor agents to mitigate spreading of powder dust containing radioactive materials.
Unit 1 reactor building cover installation completed (Oct. 28, 2011).
Radiation dose at the site is being held down due to rubble removal.
PCV gas control systems for Unit 1~3 in operation.
Maintain the PCV pressure at the same level as the atmosphere in order to control the amountof radioactive materials released from the PCV.

Unit 1 reactor building cover installation

Spraying dust inhibitor agents to the buildings
and site groundContainers storing rubble

Rubble storage area（tent and container）

Removal of rubble

5

3

【２
２】Mitigation of the Release of Radioactive Materials
Utilizing the airborne radioactivity concentration at the upper parts of the reactor buildings etc., thetotal current release rate (Cs) from Units 1 to 3 (8/2012) is estimated to be approximately
10 million Bq/hour. This is approximately 80 millionth of the release rate right after the accident.
The exposure dose at the site boundaries due to the aforementioned is assessed at 0.02 mSv/year
at the maximum (excluding the effect of radioactive materials already released until now).

Release Rate
(Bq/h)*1: Total release rate (Bq/h) of Cs‐134 and Cs‐137 was calculated based on release rate (Bq/h) of Cs‐137 as of Mar. 15 mentioned in the report of the 63rd
Nuclear Safety Commission of Japan. Total release rates (Bq/h) of Cs‐134 andCs‐137 as of Mar. 25 and Apr. 5 were calculated in the same way.
*2: Total release rate (Bq/h) of Cs‐134 and Cs‐137 was calculated based on av
erage concentration of Cs‐137 in the air measured near the west boundary of t
he site from Jun. 20 to Jun. 28. Total release rate (Bq/h) of Cs‐134 and Cs‐137
was calculated based on average concentration of Cs‐137 in the air measured
near the west boundary of the site from Jun. 26 to Aug. 12.
*3: Total release rate (Bq/h) of Cs‐134 and Cs‐137 was estimated from the resul
ts of dust concentration measurement at the upper parts of the reactor buildings
and the sea.
*4:Toatal release rate(Bq/hour) of Cs-134 and Cs-137 was estimated utilizing theresults of dust concentration measurement at the upper parts of the reactor
buildings(including Unit 1 reactor building cover and Unit 2 PCV gas control
system exit) and the sea.
*5:Toatal release rate(Bq/hour) of Cs-134 and Cs-137 was estimated utilizing theresults of dust concentration measurement at the upper parts of the reactor
buildings(including Unit 1 reactor building cover and PCV gas control system exit).

Approx. 800 trillion( 8 x 1014) Bq/h*1

1015
Approx. 2.5 trillion( 2.5 x 1012) Bq/h*1
1013

Approx. 0.29 trillion( 2.9 x 1011) Bq/h*1
Approx. 1 billion( 1 x 109) Bq/h*2
Approx. 0.2 billion ( 2 x 108) Bq/h*2

1011

Approx. 0.2 billion ( 2 x 108) Bq/h*3
Approx. 0.1 billion ( 1 x 108) Bq/h*3

Approx. 0.06 billion ( 6 x 107) Bq/h*4
Approx. 0.06 billion ( 6 x 107) Bq/h*4
Approx. 0.07 billion ( 7 x 107) Bq/h*5

109

Approx. 0.01 billion ( 1 x 107) Bq/h*5
3/15 3/25 4/4 6/20 7/26 9/1 10/3 11/1 11/26 12/28 2/1 2/24 3/27 May-3/26 -4/6 -6/28 -8/12 -9/17 -10/13 -11/10 -12/6 -1/13 -2/13 -3/7 -4/15

Jun

Jul

Aug

Evaluation Period

Release rate of radioactive materials(Cesium) per hour from Reactor Building of 1F Unit 1 - 3

6

Controlling the total amount of accumulated water ～【３３】Accumulated Water ～ControllingCountermeasures for Controlling the total amount of accumulated water
prevent groundwater leaking into buildings by pumping up sub-drain water and groundwater
bypass.
Installation of Multi-nuclide Removal Equipment (ALPS)Store/manage sludge waste and Concentrated Waste liquid etc. Planning to increase capacity.

【Unit 1~4】

【Unit 5,6】

＜High level＞＜Low level＞
Reactor blg./Turbine blg.
Waste sludge
conservation
facility

Processed
water tank

ALPS:
Advanced liquid
processing
system(constructing)

Process Main Building
High-temperature
Incineration Building

Accumulated water
processing system(Kurion/Areva/Sarry)
Desalting(reverse
osmosismenbrane)

Concentrated
sea water

Concentrated
sea water tank

Low concentrated
processed water tank
/Mega float

Purification
facility
Processed
water

Water sprinkling
Concentrated
Waste liquid

Desalting(concentration)

Highlyconcentrated
water tank

Reactor blg./Turbine blg.

Concentrated
Waste liquid
tank

7

4

【３
３】Accumulated water level has been maintained at target level
After full-scale use of SARRY from Aug. 18, 2011, the accumulated water level has been
maintained at the target level of O.P 3,000, where it is able to withstand heavy rains aswell as long-term processing facility outages(approximately 1 month).
At this point, we are continuing and enhancing Circulating water cooling.
T/B B1 Water level
［mm]

4000
Unit-2 T/B B1 Water level (mm)•Sum total of Accumulated water processing
approx. 437,150 tons in total (as of Sep. 5, 2012)

3800

•

Cs-137 decontamination factor*
3.2 X 105 in the apparatus of Kurion (as of Jun. 19, 2012)
4.0 X 104 in SARRY (as of Aug. 21, 2012)

3600

•

Chlorine concentration
Decreased from 720 ppm to approx. 3ppm
(by the reverse osmosis equipment ,as Aug. 21, 2012)
Decreased from 6,900 ppm to approx. 2ppm
(by the evaporative concentration apparatus
as of Dec. 20, 2011)

Unit-3 T/B B1 Water level (mm)

3400
3200
3000

Target levelOP3,0002800*Decontamination factor = cesium concentration of a sample before
processing / cesium concentration of a sample after processing

2600
6/17

8/21

10/25

12/29

3/3

5/7

7/11

9/14

Management of accumulated water in Turbine Building

8【３】 Future Plan of Reactor Cooling & Water Processing
System improvements will be continuously implemented.
In addition, the water circulation line will be decreased step-by-step.
Multi-nuclide removal equipment will be newly installed.
Cooling loop will be packed into the reactor building, after sealing of the waterleakage between Turbine and Reactor Buildings, and repairs of the lower parts of
PCVs have been achieved.

Buffer tankReliability Improvement

Loop Decrease

Storage tank

Reactor Building

Reactor Water
Injection Pump

Turbine Building

Bypass or Pumpup

Accumulated
water
processing
facilities

Multi-radioactive
NuclideRemovalFacilities

Facility Improvements

Groundwater

Reactor Building container
Reactor Building

CST

TurbineBuilding
Heat exchanger/
Filtering system

Stop inter-building water leakage/Complete accumulated water
processing

Material
Reinforcements Etc.

Groundwater level
地下水（Legend）：Estimated leakage route95

【３】Countermeasure against Ground Water Inflow
Water level difference(m)Pump groundwater flowing from the mountain-side
upstream of the building to change the flow path of
the groundwater.( Groundwater bypass )Reduce groundwater level near buildings (mainly on
mountain-side) with groundwater bypass to reduce
flow volume into buildings.
Installation work of the pumping wells will start from
September.

■：pumping well

Decrease of groundwater level from the present condition

After bypassing
groundwater

Current status

Pumping well

Groundwater path(mountain -> sea)

Groundwater path(mountain -> sea)

Groundwater Bypass
Pumping well

R/B. T/B

R/B. T/B

透水層
難透水層

透水層
難透水層

Groundwater inflow

Water processing

Groundwater inflow(decrease)

Water processing(decrease)

10【３】Countermeasure against Ground Water Inflow
Restoration of sub-drain system :Sub-drain is a drainage system to prevent ground water from flowing into partially underground buildings.
Clean-up tests of the sub-drain pits (shown below) : Purification processes were finished but clean-up
was not finished.
So, we have to install purification system of ground water to release into the ocean.

＜Current status＞

Sub-drain Clean-up tests results（Unit 1-4・Typical nuclide）

ground water inflow
without activating
sub-drain＜Target＞
Decreasing
groundwater level tomitigate water inflow
to buildings

Purification system

116【３】Multi-nuclide Removal Equipment (ALPS)
Existing facilities remove Cesium mainly.
manage to keep radioactive substance concentrations other than Cesiumin processed water well below stipulating dose limits based on provisions .
Installation of Multi-nuclide Removal Equipment (Inservice in Sep. 2012)
ALPS (Advanced Liquid Processing System)
A-system (50% flow): 250m3/day
Processed
water

Iron coprecipitation
processing
facility

Carbonate coprecipitation
processing
facility

Pre-processing
facility

14 towers (Adsorbent
change type)

2 towers(Column type)

Adsorption tower

SludgeAdsorbent

To temporary storage
facilities

Containers

Sampling tank(1000 tons × 4 towers)

B-system (50% flow): 250m3/day
C-system (50% flow): 250m3/day

To tank

12【３】Multi-nuclide Removal Equipment (ALPS)
Verified that it can remove target nuclides (62 nuclides) to meet stipulating dose limits
and to below N.D.
Construction of A and common system was finished,Cold test started on Aug.24.
Confirmatory tests result（example of a part of nuclides）
Reverse osmosis concentrated saltwater

Nuclide（half life）

Density limit

Sr-89(approx. 51 days)

300

12000000

N.D. <

0.28

Sr-90(approx. 29years)

30

110000000

N.D. <

0.097

Ru-103(approx. 40 days)

1000

N.D. <

1100

N.D. <

0.15

Ru-106(approx. 370 days)

100

N.D. <

1.2

Sb-124(approx. 60 days)

300

N.D. <

570

N.D. <

0.21

Sb-125(approx. 3 years)

800

100000N.D. <

0.40

Cs-134(approx. 2 years)

60

15000

N.D. <

0.29

Cs-137(approx. 30 years)

90

20000

N.D. <

0.36

Ba-140(approx. 13 days)

300

N.D. <

0.50

N.D. <

0.11

Beforeprocess

Afterprocess

30000

Overview of installation area

Mn-54
(approx. 310 days)

1000

Co-58
(approx. 71 days)

1000

Co-60
(approx. 5 years)

20

N.D. <

3700

N.D. <

700

1100

860

N.D. <

0.12

N.D. <

0.18

storage container

137【３】Situation of Accumulated water storage tanks
Oil
Separator
油分分離装置

Reactor

炉注水
Water
Injection
ポンプ

Decontamination
除染装置
Equipment

Pump

Evaporation Concentration
Water Tanks
Cesium Adsorption Apparatus
2nd Cesium Adsorption Apparatus

Flow

Cut伐採
down
木
Trees
Other areas in the site is not available forstorage tanks since they will be used forcut-down trees yard or site renovation isrequired for slopes

Desalination Apparatus

Multi-nuclide removal
facility is planed to
be installed

RO Concentration Water Tanks
Evaporation Concentration Water Tanks
Freshwater Tanks: Water Transfer Line: Existing Tank Area

Arrangement of Water Processing
Facility in Units 1 ~ 4: Additional Tank Area
(There are restrictions due to groundstrength, existing buried object, andtransmission lines, etc.): Underground Cistern

Fresh Water, RO Concentration Tanks

Installed capacity is approx. 225,000 tons (remaining capacity is approx. 28,000 tons as of Sep. 4,2012)
Adding the capacity of approx. 89,000 tons. And planning to add the capacity of approx. 380,000 tons more.

14【３】 Installation of additional processed water storage tanks
Replace square-type steel tanks by large-scale round-type steel tanks (completion:Nov. 2012)
Approx. 33,000 tons capacity
will be added
Secure/increase storage capacity
Effective use of the site

[Total capacity of existing E area tanks: 8,000 tons]

After Replace[Total capacity: 41,000 tons]

We will build underground cisterns to the place where large-scale tanks can’t be build on
the ground due to inadequate ground conditions, etc.
Water Surface Level

Earth filling

GroundPlastic Case

Triple sheets (double water shielding sheets + bentonite sheet)

Cross-section view

15

8

【４
４】Radioactivity concentration in the ocean (Onshore and offshore)
In a declining trend since the accident, and now below a detectable level.
*Notice level：Legal limit I-131…40 Cs-134…60 Cs-137…90 (Bq/L)● Northern outlet●●harbor

15km off shore● Southern outlet

Northern outlet, Radioactivity (Bq/L)

Southern outlet, Radioactivity (Bq/L)

1.0E+06

1.0E+06

1.0E+05

1.0E+05

1.0E+04

1.0E+04

Limit level (drink water level) 10Bq/L(Cs-134+Cs-137)

1.0E+03

1.0E+02

1.0E+02

1.0E+01

1.0E+01

1.0E+00

1.0E+00

1.0E-01
3/11

4/10*Scale

5/10

6/9

7/9

8/8

9/7

10/7

11/6

12/6

1/5

2/4

3/5

4/4

5/4

6/3

Limit level (drink water level) 10Bq/L(Cs-134+Cs-137)

1.0E+03

7/3

8/2

1.0E-01
3/11

Vertical: 1E-1 ~ 1E+6 Horizontal: 2011/3/11 ~ 2012/7/30

4/10

5/10

6/9

7/9

8/8

*Legend

9/7

10/7

11/6

12/6

1/5

2/4

3/5

4/4

Cs-134

I-131

5/4

6/3

7/3

8/2

Cs-13716【４４】Radioactivity concentration in the ocean (Onshore and offshore)

Harbor,Radioactivity(Bq/L)
Harbor, Radioactivity(Bq/L)

15km off shore, Radioactivity (Bq/L)

1.0E+06
1.0E+06

1.0E+05
1.0E+05

1.0E+04

Limit level (drink water level) 10Bq/L(Cs-134+Cs-137)

1.0E+03
1.0E+02

1.0E+04

1.0E+02

1.0E+01

1.0E+01

1.0E+00

1.0E+00

1.0E-01
3/11 4/10 5/10 6/9 7/9 8/8 9/7 10/7 11/6 12/6 1/5 2/4 3/5 4/4 5/4 6/3 7/3 8/2

Not detected after July 2011

1.0E+03

1.0E-01
3/11

4/10

5/10

6/9

7/9

8/8

9/7

10/7

11/6

12/6

1/5

2/4

3/5

4/4

5/4

6/3

7/3

8/2

17

9

【４】Preventing the Spread of Contamination to the Ocean
Impermeable walls will be installed by mid FY2014 to prevent contaminatedgroundwater from flowing into the ocean.
Covering and solidifying seabed soil in front of the intake canal was finished(Jul. 5,2012) to prevent diffusion of radioactive materials in the soil.
Circulating seawater purification facilities are installed to reduce radioactive
materials in the seawater in the port.
Groundwater and sea water will be continuously monitored.
Covering in front of
the intake canal (Unit1～4）
Before covering（2/26/2012）

water shielding walls
Existing seawall

Dredging

Permeable layer
Landfilling
Low-permeable layer（seaway･anchor ground）
Existing silt fence

Permeable layer

Before covering(Dredged soil dump)
After covering(in front of the intake canel)

After covering(in front of the intake canel)

Low-permeable layer

Shaiiow draft quayUnit1

Unit6 Unit5

After covering（4/29/2012）
Water Shielding wall

Unit2 Unit3 Unit4

Seabed Soil in the Port

Water Shielding Walls

18【５５】Countermeasures to reduce radiation dose at the site boundaries due to rubble, etc

Reduce the effective radiation dose at the site boundaries to below 1 mSv/year within FY2012
effective dose due to additional emissions of radioactive substances from the power station as a whole,and radioactive waste produced after the accident and stored on the site.

Concrete/metal and Cut-down trees stored in accordance with its radiation dose.
We build temporary storage facilities with shielding measures using soil and sandbags, etc.
(Aug.10, 2012)

Rubble Storage Area
Cut-down Trees Storage Area
Rubble Storage Area (Plan)
Cut-down trees Storage Area (Plan)

Storage Area

Ｇ
ＢＡ
Ｌ
Ｃ
Ｄ

Ｈ
Ｉ

Concrete,Metal
Concrete,Metal
Concrete,Metal
Concrete,Metal

D: Northern Site
E: Northern Site

Concrete,Metal
Concrete,Metal

F: Northern Site

ＦＥ
Ｍ
Solid Waste Depository

Type

Solid Waste Depository
A: Northern Site
B: Northern Site
C: Northern Site

G: Northern Site
H: Northern Site
I: Northern Site
J: Southern Site
K: Southern Site
M: Western Site

Storage Method
Container

Area Occupancy

Container
Outdoor Yard

Unit
m3
Unit
m3

35%
97%
98%
77%

Outdoor Yard
Outdoor Yard

2,000
3,000

m3
m3

84%
78%

100
49,00018,00016,00011,00012,0005,000
9,000
71,000

m3

99%
78%
83%
88%
100%
77%
100%
44%
77%

Temporary Storage Facility

Concrete,Metal
Total(Concrete,Metal)
Cut-down trees
Cut-down trees
Cut-down trees
Cut-down trees
Cut-down trees
Cut-down trees
Total(Cut-down trees)Amount410
11,000450
26,000

Container
Outdoor Yard
Outdoor Yard
Outdoor Yard
Outdoor Yard
Outdoor Yard
Outdoor Yard

m3
m3
m3
m3
m3
m3
m3
m3

Covering soil for shielding (over 1m)
Water shielding sheets

Observation holeProtection sheets

Ｊ

Ｋ

Rubble, etc.

Approx.
Protection soil
6m

Grounds
Completion of preparatory
work for first unit

Overview of Covering Soil Type Temporary Storage Facility

1910【６】 Fuel Removal from Spent Fuel Pools
Plan to start fuel removal
Unit 4 within 2 years after completing Step 2*.
Unit 3 within approximately 3 years after completing Step 2* .
As for Unit 1, based on experiences at Units 3 & 4 and investigations of rubble, and finish
fuel removal in the Phase 2*.
As for Unit 2, plan to develop a fuel removal plan based on the situation after the insidebuilding decontamination etc. and investigations of the installed facilities, and finish fuelremoval in the Phase 2*.
Plan to complete fuel removal from all Units during Phase 2*.
Plan to determine reprocessing & storing methods for removed fuels during Phase 2*.
notes: Step2:Roadmap towards restoration from the accident , Phase2:Mid-and-long term Roadmap towards the Decommissioning

Fuel removal work (image)

20

Fuel Removal from Spent Fuel Pools (Unit 4, 2013~)【６】FuelIn order to install a cover for debris removal, removing rubble from the top of the reactor
building and building a gantry for rubble removal are underway.
(Target completion date; around the end of FY 2012 for Unit 3 and around the middle of FY 2012 for Unit 4)

Unit 3: Surveyed inside the SFP using remote controlled underwater camera (April 13, 2012)
Unit 4: Surveyed on rubble dispersion inside the SFP using Remotely Operated Vehicle (March 19 ~ 21,2012), and created a rubble dispersion map (April, 2012).

Unit 3

Sep/2011

Aug/2012

Unit 4

Sep/2011

July/2012

Unit 4 2011/7

Removalarea
5th floor level

Survey on rubble dispersion inside the SFP

Pre-survey in the water of Spent Fuel Pool (SFP)
Inside of the SFP(Shot from the cask yard)
Fuel Handle

Remotely Operated Vehicle (ROV)

Propeller
Fuel Rack
Part of Fuel Handling
Machine
Inside of the SFP(Shot from the cask yard)

RubbleFuel Handle

Camera
Light

21

11

Fuel Removal from Spent Fuel Pools (Unit 4, 2013~)【６】FuelUnit4：Integrity survey of Fresh Fuels from the Spent Fuel Pool・2 Fresh Fuels were removed from the Spent Fuel Pool (July 18 – 19, 2012), andintegrity survey was performed to check corrosion (August 27 – 29, 2012).
Outline of the work
①Using a rough Terrain
crane, removing fresh
fuels from the spent
fuel pool
Packaging③To common pool
②Using a crawler crane, removing
fresh fuels to ground level.

Removal of fresh fuel from
Unit4 spent fuel pool

22

Fuel Removal from Spent Fuel Pools (Unit 4, 2013~)【６】FuelUnit4：Integrity survey of Fresh Fuels from the Spent Fuel Pool
In order to perform visual inspection and detail observation, a connecting fuel rod wasremoved on the operating floor of the common pool.
It was confirmed that rubble entered between fuel rods, neither abnormalities nor
corrosion of fuel rods and the structural member of fuel assembly was found.

①Situation of the work

③Rust on the fuel rods

②Rubble found in the fuelPhoto :Aug. 28, 2012
④Confirmed that the rust was wiped out

23

12

【６
６】Fuel Removal from Spent Fuel Pools (Water Quality Improvement)
Desalination for corrosion prevention of SFP is done in turn by reverse osmosis (RO) andion-exchange equipment. For Unit 3 and 4 desalination is ongoing.
reverseosmosisSFP water quality sampling results (Aug. 2012)
Sampling
Date

RO Unit (mobile type)

pH

condu
ctivity

Cl

Cs137

Cs134

－

mS/m

ppm

Bq/cc

Bq/cc

notes
＊Cl ,Cs137,134:
sampled on
2012.4.11

Unit 1

2012/
7/11

7.6

15.8

6

1.8E+04

1.1E+04

Unit 2

2012/
7/1

9.1

9

11

2.2E+01

1.4E+01

Unit 3

2012/
8/30

9.2

54

73

2.8E+03

1.7E+03desalinationis ongoing

Unit 4

2012/
8/17

9.6

23

31

1.8E+00

8.2E-01

desalinationis ongoing

Ion Exchange
Resin

Ion Exchange Unit (mobile type)24

transport・custody
custody）
Fuel Removal from Spent Fuel Pools （transport【６】FuelTransportation of fuels in the spent fuel pool
①Transfer fuel in the spent fuel pool to the common pool
②Transfer fuel in the common pool to the temporary cask custody area
Temporary cask custody area
・Ensure an area to receive and store the fuel removed from the spent fuel pools
・The spent fuel currently stored in the common pool will be stored in dry casks and move out of thecommon pool, and temporary stored.

watch house
crane
gate

guard
fence
Cask
pit

Storage area

Cask
pit

Ensurereceivablearea①Fuels in the spent fuel pools
are transferred to the common
pool by shipping caskＮconcrete module

排気

排気

給
気

給気

cask

②Fuels in the common pool will be
stored in casks and move to
Temporary cask custody area.

Transportation and Custody of Fuel in the Spent Fuel Pool (image)25

13

【７】Countermeasures against Aftershocks and Tsunami
we conducted detailed seismic evaluation of Reactor Buildings with finite element model considering
the building damage and conditions of the pool water at high temperatures.
Confirmed seismic safety without reinforcement against the earthquake equivalent to the Tohoku-Pacific
Ocean Earthquake (JMA Seismic Intensity Scale 6+)
The maximum shear strain of the wall was less than twentieth part of the criterion value. The seismic
safety of the building is almost equivalent to that of before the earthquake.
Future evaluation of age-related deterioration
Deterioration by heat :Stable cooling of fuel debris and fuels in SFP has been continued. Concrete was temporarily exposed to hightemperature. But deterioration of concrete won't proceed after temperature of concrete dropped to ordinary level.
Deterioration by sea water :R/B’s seismic safety as of now was confirmed by the analysis. In the analysis model, reinforced concrete
members with exposed rebar were not considered. Furthermore, we are going to conduct periodical inspections in order to confirm longterm integrity.

Reactor well

Spent Fuel Pool

Spent Fuel Pool

5thＦ

Modeling

Equipmen
4thＦ
t
3rdＦ storage
pool

Reactor Well
Equipment Storage
Pool

5F

2ndＦ
1stＦ

2F
Modeling area

Outer Wall (North)

Sectional view ofReactor Building

Outer Wall (West)

FEM Analysis Model considering wall damage

26【７】Countermeasures against Aftershocks and Tsunami
We installed a support structure at the bottom of the spent fuel pool of Unit 4.
This increased the seismic safety margin by an extra 20 %.
Installed a temporary tide barrier (OP+14m) as a countermeasure against tsunamis.
(6/30/2011)

Spent
使用済
Fuel
燃料プール
Pool

Expansion
Steel posts installed
condition （6/20/2011）

鋼製支柱の設置
Steel posts installation＞＜Afterconcrete placement＞＜Afterコンクリート壁の設置

concrete placement
condition （7/21/2011）

Concrete wall
コンクリート壁Overview of temporary tide barrier
Installation27

14

【８】 Integrity Confirmation of Unit 4 Reactor Building
In accord with indications that Unit 4 R/B was leaning, we conducted inspections as shown
below. And we confirmed that the building was not leaning and its structural integrity had
been maintained. (In May and August 2012)
We continue to conduct periodical inspections continuously. (4 times per year)。
Inspection①： confirmation of leaning（water level measurement）
Inspection②：confirmation of leaning（outer wall measurement）
Inspection③：Visual Inspection（ cracks on the concrete floor and walls )Inspection④： Concrete Strength Verification （ non-destructive inspection ）Equipment
storage pool
5F

Measurement Point

Measurement Point
Spent Fuel
Pool

Reactorwell

Opticalequipment①confirmation ofleaning（water levelmeasurement）② confirmation ofleaning（outer wallmeasurement）④ Concrete Strength
Verification （ nondestructive inspection ）③ Visual Inspection（ cracks on theconcrete floor andwalls )

28【９９】 Approach for monitoring the reactors and removing fuel debris(Unit 1)
We are going to investigate internal state of the PCV via inserting survey equipment in order to obtain
photos and to directly measure data; ambient temperatures, radiation dose rate, accumulated watertemperatures, water level, sampling and analysis of the water ,etc. (October 2012).
Investigation and repair of the PCV leakage is being considered. Inside of Torus Room wasinvestigated by CCD camera inserted via penetration on the 1st floor of the Reactor Building (June 26,2012).

Unit 1

Investigation inside PCV
X-100 X-100Bペネ
Penetration
N2 Injection Flow
Rate to RPV：
12.97 Nm3/h

SFP Temperature：30.0
deg C

D/W 2nd Floor Grating
X-100B Penetration

D/W Spray Piping

Equipment Hatch Monorail

Reactor Building Cover

FDW：3.1 m3/h
CS：1.9 m3/h
Temperature inside
PCV：Approx. 37 deg C

RPV Bottom
Temperature：
Approx. 36 deg C

Hydrogen Concentration
inside PCV
A：0.54 vol%B：0.54 vol%N2 Injection Flow
Rate to PCV：
20.20 Nm3/h

Torus Room of Unit 1
Ambient radiation dose rate inside Torus Room:Approx. 10 Sv/h at maximum (June 26, 2012)
Reference:
Radiation dose rate outside TIP Room:Approx. 5 Sv/h at maximum (July 4, 2012)

CCD Camera
with thermocouple

Torus Room

Water Level in Torus Room：Approx. OP 4,000 (June 26, 2012)

Reactor Water
Level：Not
confirmed

Water Level in Turbine Building：OP 2,630

Reactor Building*Parameters as of Sep. 5, 2012 11:00AM

Suppression Chamber

Turbine Building

29

15

【９
９】 Approach for monitoring the reactors and removing fuel debris(Unit 2)
Investigation inside was carried out with microscopes etc. via PCV penetration. (January 19 andMarch 26 & 27, 2012)
Investigation inside Torus Room was carried out with robots (April 18, 2012).
Water level was measured inside Torus Room and staircases area (June 6 and 28, 2012).
Investigation inside the PCVUnit 2

Above water surface

Under water

PCV
N2 Injection Flow Rate
to RPV：15.88 Nm3/h

Thermocouple

SFP Temperature：31.2 deg C

FDW：2.0 m3/h
CS：5.0 m3/h

Investigation inside Unit 2 Torus (April 18)
RPV Bottom
Temperature：
Approx. 55 deg C

Temperature inside
PCV：Approx. 50 deg C

Access
Route

Hydrogen Concentration
inside PCV
A：0.06 vol%B：0.07 vol%N2 Injection Flow Rate to
PCV：5.29 Nm3/h

Air Radiation inside
PCV：Approx. 73 Sv/h
at maximum

Maximum observed
Water Level in Torus Room：Approx. OP 3,270 (June 6, 2012)

Reactor Water
Temperature：
Approx. 50 deg C

Water Level of Reactor：
Approx. 60 cm + PCV Bottom

S/C Manhole(Southeast)

Water Level in Turbine Building：OP 3,291

Turbine Building

Reactor Building

Red：Radiation (mSv/h)30※Parameters as of Sep. 5, 2012 11:00AM(Unit 3)Work Environment was investigated by robots in TIP room on 1st floor of the Reactor Building for
preparation to investigate inside the PCV. (May 23, 2012)
Survey the Torus Room by robots to understand conditions inside it.（July 11/2012）
Water level was measured inside Torus Room and staircases area (June 6, 2012).
Unit ３Torus Investigation （7/11）

Unit 3

SFP Temperature：30.0
deg C

N2 Injection Flow
Rate to
RPV：16.84 Nm3/h

PCV side condition
FDW：2.5 m3/h
CS ：4.5 m3/h

RPV Bottom
Temperature：
Approx. 52 deg C

Temperatureinside PCV：
Approx. 50 deg C

South-east manhole

Water Level Survey in Torus and staircases area of Unit 3

Hydrogen Concentration
inside PCV
A：0.26 vol%B：0.25 vol%Water level

Water Level in Torus Room：Approx. OP 3,150 (June 6, 2012)

Staircases
area

N2 Injection
Flow Rate to
PCV：0 Nm3/h

全
全第
第
第一
一
一 福
福島
島第
第一
一
安
安
安全

Unit 3Torus Room
Water Level in Turbine Building：OP 3,115

Reactor Building*Parameters as of Sep. 5, 2012 11:00 AM

Turbine Building

Unit 3 staircases area
(Northwest)

Measured water level ofaccumulated water31

16