Unit 4 TEPCO Reports On Stability, Translated.

Unit 4 reactor building of Fukushima Daiichi Nuclear Power Station
For confirmation of the soundness
Results for periodic inspection (second time)
August 30, 2012
Tokyo Electric Power Co., Inc.

One. The purpose of the inspection

For the spent fuel pool and the reactor building of Unit 4, we carried out a periodic inspection,
I confirmed the soundness. (Date: August 20 to August 28 Heisei 24 second time) this periodic inspection
In addition to the first measurement point first, and a local bulge of the outer wall surface has been identified in the first round
I inspected also the place for more information related to inspection.

“The contents of the report so far”
(25 – May 24 May 17, 2006, 2010) regular inspection first round (1)
Confirmation of the slope of the building [item] ① (measured water level), (measurement of the outer wall surface) ② check the slope of the building
Visually inspect ③, ④ check the strength of concrete
Although part of the upper part of the outer wall, [Overview] The result has been damaged, the frame of the spent fuel pool wall thickness is important
Sometimes thick and 140cm ~ 185cm, also concrete enough, no cracks or slope
Strength is secured, is ready to store spent fuel safely.
· A local bulge in the outer wall surface was confirmed.
More inspection outer wall surface of local swelling (2) has been confirmed
(21 – June 06 June 2012, to report results, Nuclear Safety Agency March 25 (6))
Deformation behavior of the outer wall surface [item] ①, ② strength concrete, visual inspection ③
Although a local bulge in the western and southern outer wall surface has been checked against the outer wall surface near [Summary Results,
Visual inspection of the results of the check and cracking of concrete strength, affects the structural strength
Such damage could not be confirmed.

2. ① check the slope of the building inspection results (water level measurement)

Using that it is always horizontal, wells and water  The spent fuel and reactor floor, 5th floor
Measuring the (water) distance of the surface of the water in the pool, I went to check if there are any building tilts.
Outline of inspection results so far]
· Confirmed that times a 3 H24.2.7, H24.4.12, of H24.5.18, the building is not tilted.

If a building 1) is not inclined

Distance                                                                Distance
About the same distance

 

If the building 2) is tilted

Distance                                                                Distance

Different distances

Words, top clockwise:

: Measurement point (※ 1)

Spent fuel
Pool

About 12m

About 10m

Reactor
Well

Floor, 5th floor

Equipment storage
Pool

North

Measurement point (floor 5th floor)
Using that it is always horizontal, wells and water  The spent fuel and reactor floor, 5th floor
Measuring the (water) distance of the surface of the water in the pool, I went to check if there are any building tilts.
Outline of inspection results so far]
· Confirmed that times a 3 H24.2.7, H24.4.12, of H24.5.18, the building is not tilted.
※ 1: The measurement point, appropriately set by the progress of the construction work for taking out cover fuel.
2. ① check the slope of the building inspection results (water level measurement)

As a result of water level measurement, since the measurement of the four corners is almost the same, and spent fuel floor 5th floor
We confirmed that the reactor water of the well is parallel to the pool and as before.
Outline of inspection results so far]
· Confirmed that times a 3 H24.2.7, H24.4.12, of H24.5.18, the building is not inclined

 

Words left to right:

Floor, 5th floor
Steel ruler
Measured value
The spent fuel pool
Well water reactor

※ 1 measuring method
※ 1: since it is carried out by visual measurement, some
Possible error.

※ 2 measurements of water level
Unit [mm]

※ 2 measurements of water level
Unit [mm]
※ 2: The water level varies from day to day by the operating conditions of the cooling equipment.
※ 3: H24.2.7, we measured the only reactor well.

 

2. ② measurement of the outer wall surface inspection results (measurement point)
By placing a fixed point at the top and bottom of the outer wall surface , measured by optical equipment, ※ 1 horizontal difference of the outer wall surface
Make sure, we have to confirm the nature of the deformation.
Outline of inspection results so far]
Although the detailed inspection, and the outer wall surface (H24.5) in (H24.6), showed a local bulge in the outer wall surface of the first
Confirmed that the building as a whole is not tilted.

※ 1: horizontal distance between the fixed point fixed point on the first floor and the upper floor.
Measurement point

 

2. ② measurement of the outer wall surface inspection results (measured)

Difference with the results of previous inspection: [Legend] ()
West
South
Horizontal distance between the fixed point and the upper floor floor fixed point 1: ※ 1 horizontal difference
※ 1 calculation results

 

2. ② measurement of the outer wall surface inspection results (Discussion)
 horizontal difference is similar to the value of the inspection and the outer wall surface detail (H24.5) and (H24.6) first round
Forming deformation of each point showed a similar trend.
The difference has occurred and some measurement results  last time, the measurement error of the optical instrument is about 2mm ±
And it is, can cause an error of up to about 4mm horizontal difference, concretions
About 7 ~ 13 × 10-6 (thermal expansion coefficient of thermal expansion of the port
/ ℃ by) about the difference between the average monthly temperature in July and May
It is conceivable that there is a possibility that there is a difference of 2 ~ 4mm.
Part of the outer wall on the south side, I am strong and visually check the second floor and the west side of the bulge seen 
Crack width of 1mm or more to implement-check, that could affect the structural strength is seen
Although not considered a small decrease in stiffness, evaluation analysis that ignores the stiffness of the wall
Implementing value, it has been confirmed that there is no problem in the seismic safety of the reactor building ※ 1.
On the west side exterior wall on the second floor of the bulge seen , based on the comments in the meeting ※ 2 hearing,
Conduct detailed investigation of cracking, cracking of up to 0.3mm width, as shown in the photo on the next page
I confirmed the reports.
However, if it is 0.3mm wide cracking has been identified recently, on the strength and durability, the problem
It is not at a level to be.

※ 1: “according to the study report on seismic safety in consideration of local swelling of the outer wall of the reactor building of Unit 4 of Fukushima Daiichi Nuclear Power Station”
(June 2012, Tokyo Electric Power Co., Inc.)
※ 2: “Kai hearing about the structure of the 11th-building” (August 07, Heisei 24, NISA, nuclear safety)

 

For cracks in a local swelling of the outer wall [Reference]

The exterior wall on the second floor west side of the bulge is seen cracking a maximum width of 0.3mm was confirmed.
In addition, if it is 0.3mm wide cracks has been identified recently, on the strength and durability, the problem
It is not at a level to be.

Inner surface of the outer wall between the West 3 – 2 2 ① floor west

(0.1mm crack width)

Inner surface of the outer wall between the West 4 – 3 2 ② floor west
(0.3mm crack width)

Between the inner surface of the outer wall 5 – West West 4 floor 2 ③
(0.2mm crack width)

2. Visually inspect the inspection result ③
I made ​​a ※ 1 visually confirmed that there are no cracks in concrete floors, walls . Width 1mm or more
If there is such cracks are repaired properly performed.
Outline of inspection results so far]
Significant crack-width of 1mm or more detailed investigation was not confirmed in the outer wall surface (H24.6) and (H24.5) first round.
※ 1: inspection carried out to the extent possible without interfering with the work cover for fuel extraction.

※ 2 crack Scale: measuring the width of the crack
What I want to. Applied to the target point scale
Read the width of the line on the scale.

2. Visually inspect the inspection result ③
Result of visual inspection, as well as the inspection results so far, more than 1mm of rebar corrosion cracking and
Cracks that may have not been confirmed.
Outline of inspection results so far]
And • (H24.5) study in detail the outer wall surface (H24.6), significant cracks more than 1mm width was not confirmed first round.

 

Inspection points [legend] – in pink

#1 – west wall

#2 south

2. Visually inspect the inspection result ③

Inspection points [legend] – in pink


#3 Sidewall surface SFP

#4 The west side (inner wall)


West side 5 (Exterior)

(Exterior) south face 6

2. Visually inspect the inspection result ③

Inspection points [legend] – pink
Inspection points [legend] – blue

Wall surface 7 SFP (west)

8. Sidewall surface SFP (south)


9. Sidewall surface  SFP (east)


10. Sidewall surface SFP (west)

※ 1: place that was added in order to access is now available.

2. ④ strength concrete confirmation of inspection results
 Non-destructive testing (such as the Schmidt hammer ※ 1), measuring the strength of concrete in the frame
Then, I made sure ※ 2 is equal to or greater than the strength design criteria.
Outline of inspection results so far]
And • (H24.5) further investigation in outer wall (H24.6), it was confirmed that the design strength is equal to or greater than all first round.
※ 2: inspection carried out to the extent possible without interfering with the work cover for fuel extraction.

Nondestructive inspection
(Schmidt hammer ※ 1)

Flow of non-destructive testing
※ 1 Schmidt hammer method: A method that damage the concrete, to estimate the impact strength due to the return.
Is a non-destructive inspection techniques that can be inspected without damaging the structure.

2. ④ strength concrete confirmation of inspection results
※ 1 The following figure shows the location to check the strength of the concrete.

※ 1: The measuring point in the vicinity of the last measurement position
I was measured at slightly different positions.
Target locations [Legend] (pink dots)

2. ④ strength concrete confirmation of inspection results
Results confirm concrete strength, as well as the inspection result so far, in all measurement points
I have confirmed that it is more than the strength of the design criteria (22.1N/mm2). In addition, the measurement point before
Considering the measurement error of the Schmidt hammer ※ 1 and that slightly different position and time,
Say what the result of this measurement is not a big difference compared to the previous one.
Outline of inspection results so far]
And • (H24.5) further investigation in outer wall (H24.6), it was confirmed that the design strength is equal to or greater than all first round.

※ 1: (August 1958, Japan Society for Testing and Materials) “(draft) guidance method for determining the compressive strength of the concrete implementation by Schmidt Hammer”
According to the experimental values ​​and the expression intensity determination about 3N/mm2
Observed variations in degree.

Results confirm the strength of the concrete

(purple lines) Periodic inspection first round (H24.5)
Further investigation and outer wall (H24.6)

(beige lines) Time (H24.8)

(red line) Strength design criteria


Measurement points

Summary
Results of periodic inspection the second time , buildings are not inclined as a whole, to influence the structural strength
Cracks that are not seen, such as shown in Figure ぼ, concrete strength and has adequate
I was confirmed.
 4 reactor building of Unit state is not a big change compared to the first round during regular inspections,
Is ready to store the spent fuel safely.
Future , we will continue to see the changes over time during regular maintenance.

———————————————————————
Document 2

Fukushima Daiichi Nuclear Power Station Unit 4
“Spent fuel pool” and “reactor building”
About the health of
August 30, 2012
Tokyo Electric Power Co., Inc.

 

Introduction
• the Unit 4 reactor building, has become a state building was damaged by a hydrogen explosion
Were able to confirm the status of damage, but debris removal proceeds, and take out the fuel
Such as that the design for this cover was progress, conditions for performing seismic assessment was determined
From the reactor, assuming the fuel extraction in the pool during scheduled to start from the end of next year
I made ​​a seismic safety evaluation of buildings ※ 1.
• In this evaluation, (intensity of 6 +) is about the same as from an earthquake of Tohoku-Pacific Ocean Earthquake
That the earthquake resistance of the reactor building is adequate, including the spent fuel pool also produced
Was confirmed.
• We are steadily efforts to retrieve the fuel in the pool to continue
Come.
※ 1: according to the investigation report concerning the seismic safety and reinforcement of the current state of the reactor building at the Fukushima Daiichi Nuclear Power Plant ”
(Part 1) (August 30, 2012, 2010) (Supplement) ”

 

Contents
Removal of building rubble at the top of the building 1. Has been completed
This reinforced the bottom of the spent fuel pool 2.
We have to check the status of the external damage in the building 3.
We have evaluated the seismic safety was assumed at four fuel extraction.
5 reactor building. Has secured sufficient seismic safety
The spent fuel pool 6. Has secured sufficient seismic safety
We have been regularly checked 7.
We are gotten by the government to confirm status 8.
We are advancing the installation work for taking out cover fuel 9.
Steady progress in the removal of the fuel 10. Pool
[Reference]
The positional relationship between the frame and the support precursor 1 spent fuel pool.
The spent fuel pool 2., Water is not compromised in structure
Summary of the results of the second periodic inspection 3.
Links Related Documents 4.

Removal of building rubble at the top of the building 1. Has been completed
The absence of rubble at the top (5th floor) Opefuro [southwest side]
(July 05, Heisei 24 shooting date)
Situations where there is debris on the top (5th floor) Opefuro [southwest side]
(Date: 22 September 2011 shooting date)

Range building removal
South side west side south side west side
• operating floor of the reactor building (below, Opefuro) such as columns and beams of the roof and the upper
Removal of building rubble, work was completed on July 11, 2012.
• Currently, large equipment is on Opefuro (lid of the reactor pressure vessel, the containment vessel)
We have been carried out between October to late July the removal of.
• Weight is light at the top of the building significantly due to removal of building rubble and large equipment
(4700t about).

Opefuroreberu – spent fuel pool
(Floor level 5)
Range building removal
Opefuroreberu – spent fuel pool
(Floor level 5)

 

This reinforced the bottom of the spent fuel pool 2.
• In the evaluation was conducted in May of 2011, the spent fuel pool, adequate seismic safety
I have confirmed that it is secured.
• In addition, the reinforced concrete columns and steel wall at the bottom of spent fuel pool, construction
We are improving the margin over 20% compared to the previous earthquake. (Completion of construction 30 July 2011)

May 21 of 2011 ※ 1, 15 June 2011 ※ 2, photography, May 20, 2009 31, 2011 ※ 3

① check the status of the external damage in the building 3.
• removal of debris from the fact that the reactor building has progressed, by visual confirmation, loss of floor slabs and walls
I check the status of the wound.
[Causes of damage]
• The cause of the explosion of Unit 4 is hydrogen, hydrogen gas generated at Unit 3 via a duct pipe
We estimate that for each floor that flows into the reactor building of Unit 4.
Status of damage]
(Damage condition of floor slab floor 3,4,5)
Relatively thin near-floor duct route possible occurrence of a hydrogen explosion and the floor slab thickness (
Much damage has been confirmed in 25 ~ 30cm) length.
(Damage condition of the walls of the floor 3, 4, 5)
Damage to the wall portion, has been highly dependent on the wall thickness, more or less damage in the case of 65cm wall thickness,
65cm wall damage over wall thickness is reduced.
Was a thick wall of sound, around the reactor containment vessel and the spent fuel pool wall seismic important.
– The effects of salt spray and seawater injection]
• Occurrence of juice and salt spray corrosion of reinforcing steel by water injection, for important sites, the rust on the seismic
Deterioration such as swelling of the concrete by is not permitted.
– Repair of damaged portion]
• For sites that require repair of damaged places, from the viewpoint of improving the future repair durability
Will be conducted.

 

② confirming the status of the external damage in the building 3.
[Figure] damage condition of the first and second floors
In visual confirmation was sound wall slab floor ※ 1.
※ 1: The regular inspection was conducted in May Heisei 24 years, have confirmed a local bulge in the western and southern part of the outer wall on the second floor, and reduction in the strength of concrete
There is no large cracks. Study on seismic safety engages considering local swelling of the outer wall of the reactor building Fukushima Daiichi Nuclear Power Station Unit 4 (
25th June 2012 report Ru).

First floor plan
N
Second floor plan

Sound wall: Demolished wall: Demolished floor
: (Mm) Thickness: Floor figures some floor damage
(Mm) Wall Thickness: Numeric
: Duct route: some wall damage

 

③ confirming the status of the external damage in the building 3.
Damage to the floor situation [Figure 3]


(top to bottom on left)

Of damage the floor duct
Check around the root
Health: over 25cm thick floor
Much damage: 25cm thick floor

Ultra-65cm wall thickness
: Less damage

Wall thickness of less than 65cm
: Heavy damage

④ confirming the status of the external damage in the building 3.
Damage to the floor situation [Figure 4]

Of damage the floor duct
Check around the root
Less damage: over 25cm thick floor
Much damage: 25cm thick floor

Ultra-40cm wall thickness
: Less damage

Wall thickness of less than 40cm
: Heavy damage

⑥ you check the status of external damage in the building 3.
Outer wall damage condition [Figure]
• or more walls of the third floor has been totally damaged by hydrogen explosion except a part of the northeast.


Clockwise starting upper left:

West wall (elevation)

South wall (elevation)

North wall (elevation)

East wall (elevation)

[Legend]
Demolished Building Exterior: brown
some damage exterior wall: yellow
(Including point bulge)
healthy outer wall: grey


(left to right across top)

Structural frame for supporting the fuel handling machine

Fuel handling machine

The spent fuel pool

(inside image descriptions upper left going clockwise)

Opefuro on the (5th floor)
Complete removal of rubble

Fuel handling machines, etc.
Of the weight

Damage reflects the situation

Computer analysis model
(Reflects damage condition)

Both diagrams
brown: total collapse
yellow: partially sound
grey: sound

5 reactor building. Has secured sufficient seismic safety
• Seismic safety is approximately equivalent to a building, even when compared with healthy before the earthquake.
• The reason for this is considered below.
At the top of the building is light weight greatly damaged building rubble removal of ①, seismic force is reduced.
Thick walls around the reactor containment vessel and the spent fuel pool wall ② is healthy as before the earthquake.

Results of the evaluation of the seismic safety (※ 1 strain shear wall)

Blue: ※ 2 before the earthquake(Building healthy)

Yellow:※ 3 immediately after the earthquake
(Before debris removal)

Pink: This evaluation
※ 4 when removing fuel

floor level across bottom of chart

※ 1: modifications to the force acting in a direction parallel to the inner surface of the object: shear strain
※ 2: (April 2010) (Revision 2) Interim Report of the seismic safety evaluation results with the revision of the “Guidelines for seismic design review on Nuclear Power Reactor Facilities”
※ 3: (May 28 in 2011) “(1) according to the investigation report concerning the seismic safety and reinforcement of the current state of the reactor building at the Fukushima Daiichi Nuclear Power Plant”
※ 4: “(1 thereof) (Supplement) relating to the investigation report concerning the seismic safety and reinforcement of the current state of the reactor building at the Fukushima Daiichi Nuclear Power Plant” (August 30, 2012, 2010)
※ 5: According to the Association (NEC) JEAG-4601-1991 nuclear power plant seismic design technical guideline value: Evaluation Criteria

The spent fuel pool 6. Has ① Do You ensure adequate seismic safety

Strain and stress generated sufficient precursor of the spent fuel pool, is below the reference value evaluation
I have to ensure seismic safety.

Sufficiently small, the generated stress and strain of precursor pools are lining the inner surface of the pool
Spent fuel pool water (6mm stainless steel plate having a thickness of about) lining material to damage from
I thought that there is no possibility of leaking (see Reference 2).

yellow
※ 1 immediately after the earthquake
(Before debris removal)

pink
This evaluation
※ 2 when removing fuel

left
Strain of rebar
Evaluation results of the (tensile)

right
※ 4 out-of-plane shear force (※ 5 margin)
The evaluation results of

※ (May 28 in 2011) “(1) according to the investigation report concerning the seismic safety of the status quo and reinforcing of the reactor building at the Fukushima Daiichi Nuclear Power Plant” 1
※ “(1 thereof) (Supplement) relating to the investigation report concerning the seismic safety and reinforcement of the current state of the reactor building at the Fukushima Daiichi Nuclear Power Plant” (August 30, 2012, 2010) 2
※ According to (Japan Society of Mechanical Engineers) standard prestressed concrete containment vessel standard three nuclear facilities for power generation
※ 4 out-of-plane shear force: force that causes a shift in the direction of wall and floor press is pulled out
※ margin 5: Shear / shear force occur

The spent fuel pool 6. Has ② Do You ensure adequate seismic safety
• very thick on top, ※ 1 spent fuel pool wall, the entire pool, in the very thick wall ※ 2
Because they are supported, even though the outer wall and the floor slab is damaged, and the equivalent resistance before the earthquake
Of seismic has been secured. Because of this, the land of the same extent as Tohoku-Pacific Ocean Earthquake again
(Intensity of 6 +) even in the event of earthquakes, I have confirmed that it is safe.
※ spent fuel pool wall thickness 1 140cm ~ 185cm (Reinforced Concrete)
※ wall to support the spent fuel pool 2 160cm ~ 185cm Thickness (Reinforced Concrete)

 

left image
Wall to support the fuel pool (health)
(Pre-built concrete wall)
(160 ~ 185cm thick)

right image
The spent fuel pool wall (intact)
(140 ~ 185cm thick)

We have been regularly checked 7.
• Through regular inspections four times a year, the health of the spent fuel pool and the reactor building
Make sure.
• May 25 to 5 May 17, 2006 Heisei 24, carried out on 28 August 20 to August 24 Heisei 2nd 1st
Then, it was confirmed that there are no problems with the inspection results (summary of the inspection results, see Reference 3).
① Verify that the building is not tilted (measured water level)
③ visual inspection
④ check the strength of concrete
Fixed point
The outer wall surface of ②

We are gotten by the government to confirm status 8.
• In addition Nakatsuka Deputy Minister on 23 April 2012, the Minister Hosono other government officials on May 26
I We have conducted an inspection of the Unit 4 reactor building.

 

top
Spent fuel pool from the gantry provided on the fifth floor
(May 26, 2012, 2010) panoramic tour of Le

lower
Reinforcement on the bottom of the spent fuel pool in the 2nd floor
(23 April 2012) inspection of the status of

9. We are advancing the installation work for taking out cover fuel
• support of fuel handling equipment, fuel extraction cover, remove fuel the development of the work environment and
Established for the purpose of suppressing diffusion scattering of radioactive materials arising from the work.
• set out on the 17th of April 2012, the current work, we have been the foundation work.

Complete removal of rubble
(Scheduled for October 24, 2010)

Structural frame for supporting the fuel handling machine installation

Fuel handling machine
Supporting structural frame

 

Structural frame for supporting the crane installation

Structural frame supporting crane

Structural frame supporting the crane
The load to the reactor building
We do not spend

Roof and exterior wall installation

Roof and exterior wall

An illustration, the model and outline
It is an image that shows,
Unlike the actual structure
There is a case.

10. I steadily extraction of fuel in the pool
• After completion of the extraction cover fuel storage state to a more stable fuel
Using a transport vessel shared pool in the power plant on to check the status of the fuel
Transported. The start of the fuel taken out, all year 2013 is the goal.

Image retrieval tasks of the fuel pool

clockwise upper left start:

Fuel handling
Equipment
Crane
Fuel handling machine

Cover for fuel extraction

Partition maintenance work environment (in dotted line)

The spent fuel pool

Fuel assembly

Spent fuel storage racks

Shipping container for campus

Fuel taken out
—————
Transport premises
Shared pool

The positional relationship between the frame and the support precursor spent fuel pool [Reference 1]

Reinforcements
(Concrete walls, steel post)

The spent fuel pool

Image of the flow of power and distribution of the spent fuel pool
(- Cross-sectional view ① ‘① reactor building)

 

(Taken July 05, 24, 2010) West side south side photo
Pre-removal range

Third floor plan
The spent fuel pool

4th floor plan
The spent fuel pool

1st floor

2nd floor

The spent fuel pool water ① [Reference 2] is a structurally does not leak
• inner pool is lined with stainless steel plate
• The reinforced concrete of a thickness of about 140 ~ 185cm, the spent fuel pool, the thickness further
It is lined with stainless steel sheet of about 6mm.
• There are no holes for drainage and piping to penetrate the sides and bottom of the pool
Circulation and water in the pool, the water pouring water gap from the top of the pool, pool overflowing from the upper edge
Has been done in a way that is recovered in the surge tank, where the pool water is discharged on the structure
There are no holes for drainage pipes and that passes through the bottom and sides of the pool which might be.
• Monitoring leakage from the spent fuel pool
· We constantly monitor the water level in the surge tank clearance * 1 minute, evaporation of water from the water pool
I have done an appropriate supply. Even if the pool water gap leakage due to damage of piping, etc.
Can be detected as an abnormal lowering of the water level in the surge tank.
• piping for irrigation water in the pool so that no backflow
· Check valve that does not require the power is installed in the injection pipe to the pool, Man
The pool water outflow pipe to reflux for one, even if broken, backflow prevention valve is closed
So that there is no such thing.

The spent fuel pool ② [Reference 2] is that water does not leak in the structure

Gap surge tank * 1:

Tank that has been established in order to receive the water that overflows from the spent fuel pool

The structure of the spent fuel pool

 

across top left to right
Backflow valve
Water pouring from the top of the pool
Spent fuel
Water overflowing
Surge tank clearance

——
Fuel pool
——-
around bottom left to right counterclockwise:
Pump
Disclosure
Detection equipment
Stainless steel having a thickness of about 3mm
Lining of the plate
Steel post
A thickness of about 140 ~ 185cm
Reinforced concrete
Concrete
Filling
Reactor containment vessel

Gap surge tank * 1:
Tank that has been established in order to receive the water that overflows from the spent fuel pool

 

① [Reference 3] Summary of the Second Regular Inspection Results
• inspection period
August 28, 2012 August 20, Heisei Heisei 24
• Inspection Results
Confirmation of the slope of the building ① (water level measurement)
Since as before, the measured value of the four corners of the pool is about the same, and spent fuel floor 5th floor
I it was confirmed that the water of the well parallel reactor pool and is building is not tilted.

② measurement of the outer wall surface
※ 2 horizontal difference, and an outer wall surface detail (H24.5) first round
Almost the same as the value of the inspection (H24.6), change of each point
Form is a similar trend.
Western and southern part of the second floor was observed bulge The
For exterior wall, if you ignore the stiffness of the wall
Analysis evaluated assuming a, resistance of the reactor building
※ 3 Do You Make sure that there are no problems with the seismic safety

Measurement point
※ fixed point fixed point and the upper floor floor 2:1
Horizontal distance between the

※ 3: (25th June 2012) according to the investigation report on seismic safety in consideration of local swelling of the outer wall of the reactor building of Unit 4 at the Fukushima Daiichi Nuclear Power Plant

② SUMMARY [Reference 3] The 2nd Regular Inspection Results
③ visual inspection
Result of visual inspection of the wall as before, to support the pool floor and walls, the spent fuel pool,
Reinforcement corrosion due to cracking and salt (the crack width will need to consider in terms of durability) 1mm or more
Was not confirmed that there is a possibility of cracking.
④ check the strength of concrete
As before, has exceeded the (22.1N/mm2) strength design criteria at all points, adequate
I have confirmed that this is a structural strength.

Reference links related materials [4]
• Ministry of Economy, Trade and Industry of the original report in accordance with the study concerning the seismic safety and reinforcement of the current state of the reactor building of the Fukushima Daiichi Nuclear Power Station Company ”
(May 28 in 2011) “(1) for submission to the NISA nuclear power
http://www.tepco.co.jp/cc/press/11052801-j.html
• “Installing the completion of construction on the bottom of the support structure the spent fuel pool of Unit 4 reactor building Fukushima Daiichi Nuclear Power Station” (30 July 2011)
http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110730_02-j.pdf
• “About this overview and start of construction plans for taking out cover fuel Fukushima Daiichi Nuclear Power Station Unit 4” (16 April 2012)
http://www.tepco.co.jp/cc/press/2012/1201925_1834.html
• “Unit 4 reactor building] [News from TEPCO is not tilted, it will not break in the earthquake, including the fuel pool”
(26 April 2012)
http://www.tepco.co.jp/nu/fukushima-np/info/index-j.html
• “The results of the inspection to confirm the soundness of the Unit 4 reactor building at the Fukushima Daiichi Nuclear Power Plant” (May 25, 2012, 2010)
http://www.tepco.co.jp/nu/fukushima-np/images/handouts_120525_07-j.pdf
• “report to the Nuclear and Industrial Safety Agency Ministry of Economy, Trade and Industry of seismic safety evaluation in Fukushima Daiichi Nuclear Power Station Unit 4” 24, 2010 (
June 25, 2009)
http://www.tepco.co.jp/cc/press/2012/1205832_1834.html
• “For complete removal of building rubble at the top of the reactor building of Unit 4 at the Fukushima Daiichi Nuclear Power Plant” (July 11, 24, 2010)
http://www.tepco.co.jp/nu/fukushima-np/images/handouts_120711_01-j.pdf
• Ministry of Economy, Trade and Industry of the report relating to the investigation concerning the seismic safety and reinforcement of the current state of the reactor building of the Fukushima Daiichi Nuclear Power Station Company ”
(Part 1) (August 30, 2012, 2010) (Supplement) “for submission to the Nuclear and Industrial Safety Agency
http://www.tepco.co.jp/cc/press/2012/1217264_1834.html
• “About (Part 2) the results of periodic inspection to confirm the soundness of the Unit 4 reactor building at the Fukushima Daiichi Nuclear Power Plant” (August 30, 2012, 2010)

 

 

 

 

 

 

 

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