“Development of a technology to investigate inside theReactor Primary Containment Vessel (PCV)”- Results of site test “Investigation B1” on grating around thepedestal inside Unit 1 PCV -April 30, 2015
Tokyo Electric Power Company
The content of this material includes the output of the international Research Institute for Nuclear Decommissioning (IRID)
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1. Investigation scope
Purpose: For Unit 1, an investigation is to be conducted in order to collect information on “the 1st floor
grating inside the Primary Containment Vessel (PCV)” from the robot inserted through X-100B
penetration pipe.
CRD*4 rail
: Access route (counterclockwise): Access route (clockwise)

HVH*2

MS *1 pipe

B0, ～ B18, Counterclockwise route～C11, Clockwise route
C0,

B17,

B16,

Access points (planned)

B18,

Pedestal Opening

B15,

C11,

Investigation device

B14,
C10,

B13,

C9,

B12,

C8,
B11,

PLR*3 pump

C7,

B9,

C6,

PLR*3 pipe
C5,

B8,
B3,

C3,
B1,

B2,

C1,

Clockwise access route(April 15 and 16, done)

B4,

B7,
B6,

C2,
C0,

B0,

X-100B*1 Main steaming system*2 Air conditioning unit
*3 Reactor re-circulation system*4 Control stick drive system

B5,

C4,
※2*2
HVH
HVH

B10,

Opening toaccess “the 1stfloor”
Counterclockwise access route( April 10 and 18, done)

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12. Access route along counterclockwise (actual results)
 Due to fallen objects found on the access route planned, the route was changed,
and the investigation was conducted.
 The investigation device was stuck between the points of B14 and B15.

B17,

B16,

B18,B15,

Approx. 20mm

Spot where
the device
stuck

B14,
B13,Approx. 20mm
B12,
B11,
B9,
B8,

Approx. 20mm

B5,
B3,

Main fallen objects
Route planned
Route investigated(2015/4/10)

B10,

B1,
B0,

B4,

B7,
B6,

B2,

Approx. 20mm

X100B penetration pipe
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3-1 Investigation results (Counterclockwise: done on April 10)
 The following data have been obtained through the investigation up to the point B14.

CRD rail
HVH

Investigation
point

Investigation resultsOpening toaccess thebasement

・For B2 investigation planned to be conducted (investigationon the basement around pedestal) , it was confirmed that
there is an accessible opening at the basement, and thus,
there are no obstacle objects existed around it.

CRD rail・Yet to be reached at CRD rail.
・Images taken with a camera facing towards CRD rail at theend point where the robot reached at have been evaluated, tofind that CRD rail can not be visually identified .

HVH
Pedestal
opening

B14,
B13,

PLR pump
B12,

Opening toaccess “the1st floor”
HVH

B3,
B1,

B2,

B4,

B11,
B9,

PLR pipe

B10,
B8,

B5,
B7,

・No significant damages are found on existing facilities(HVH, PLR pipe, and pedestal walls, etc.)
On access route・Data on the temperature and radiation dose have beenobtained at each investigation point.

B6,

B0,

X-100B penetration pipe

* The first investigation device was stuck and ended up being disabled to beretrieved, therefore, it has been left inside the PCV after its corresponding
cable was cut. (Apr. 13, 2015)
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3-2 Investigation results (Clockwise: Done on April 15 and 16, 2015)
 The following data have been obtained through the investigation up to the point C11.

CRDレールInvestigation point

Investigation results

HVH
MS pipe
HVH

On access route

C11,

B14,

C10,

B13,

C9,

PLR pump

B12,

・No significant damages have been found on
existing facilities (PLR pipe, walls inside the PCV, andHVH, etc.)
・Data on the temperature and radiationdose have been obtained at each investigation point.

C8,
B10,
B11,C7,

PLR配管

C6,

HVH

B8,

C5,

HVH
C4,

B3,

B4,

C3,
C2,
C1,

B1,

B2,

C0, B0,

B7,

B5,
B6,

：Route investigated on Apr 15, 2015.
：Route investigated on Apr 16, 2015.

X-100B
penetration pipe

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3-3 Investigation results (Clockwise: Done on April 18, 2015)
 With the second investigation device, re-investigation on counterclockwise wasconducted to obtain the following information.
CRD rail
HVH

Spot where thedevice stuck

HVH

Investigation pointInvestigation results

Check the route of thecable remained

・The cable being left around the opening
to access the basement is confirmed ofhaving no problem with B2 investigation.

Investigation device
stuck

・Checked on the condition of thecrawler of the device stuck.

Check the access route
up to CRD rail

・The access route up to CRD rail goes
through a narrow part between
structures, which resulted in theinvestigation device having been disabled
to pass through.

B14,
B13,

PLR pump
B12,

Opening toaccess “the1st floor”

B11,
B9,

PLR pipe

B10,
B8,

HVHB3,
B1,

B4,

B5,

B2,

B0,

X-100B penetration
pipe

B7,
B6,

* A pan-tilt camera used for retrieving the device became dysfunctional due to, seemingly,
the radiation effect, hence, it was determined to leave the second investigation device inthe spot where will not interfere with future works inside the PCV (around C2 on the wallside of the PCV) . (dated Apr. 20, 2015)
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54-1 Images (Opening to access the basement)
Taken from B4
・It was confirmed that there is an accessible opening at thebasement for B2 investigation planned to be conducted, and thus,
there are no obstacle objects existed around it.
HVH

HVH

B14,
B13,

PLR pump
B12,

Opening toaccess “the1st floor”

B11,
B9,

PLR pipe

Approx. 50 mm

B10,
B8,

HVH
B3,

B1,

B4,

B2,

B0,

B5,
B7,
B6,

Spot available forinserting the device
X-100B
penetration pipe

Approx. 20 mm
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4-2 Images (HVH (D))
Taken from C2
No significant damages are found on HVH (D)Inlet
MS pipeC11,

HVH（D）C10,

PLR pump
C9,
C8,
C7,

PLR pipe

HVH foundation

C6,

HVH （E）

C5,

HVH (D)

C4,
C3,
C2,
C1,
C0,

X-100B Penetration pipe

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4-3 Images (PLR pump (A))
Taken from C2
No significant damages are found on PLR pump (A).

PLRポンプMS pipe
C11,

Cable around
PLR pump

C10,

PLR pump (A)
C9,
C8,
C7,

PLR pipe

PLR pump
C6,

HVH （E）

C5,

HVH (D)

C4,
C3,C2,
C1,
C0,

Supporter

X-100B penetration
pipe

Wire pipe
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4-4 Images (Wall inside PCV)
Taken from C10
No significant damages arefound on the wall inside PCV.
Insidewall ofPCVMS pipePedestal opening

C11,
C10,

PLR pump (A)
C9,
C8,
C7,

PLR pipe
C6,

HVH （E）

C5,

HVH (D)

C4,
C3,
C2,

Foot of a ladder

Wall inside PCV

C1,
C0,

X-100B penetrationpipe

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95. Results obtained after processing the images of CRD
 Shooting was performed towards the direction of CRD rail at the end point where thedevice reached at (around B14) during the investigation along counterclockwise route. The
images taken were processed but CRD rail could not be visually identified.
Noise removing process andlayering multiple images process.
(approx. 2,000 images used)

Wire for PLR
system motoroperated valve

CRD railPlace where is supposedly
CRD rail located.

Comparison

Image (taken at 6:00 PM, Apr. 12)
Noise removal and layering
multiple images.
(approx. 2,000 images used)

Images after processing done

Images by mock-up test

Place where is supposedly
CRD rail located.

For the image processing methods, multiple
processing (addition of images = layering) andaverage processing (No. of images added up /No. of images used) were applied after finishingpre-treatment such as emphasizing contrasts
among several images.
Image (taken at 2:00 PM, Apr. 18)

Image after processing images taken
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106. Measurement results for temperature and radiation dose rate
Temperature and dose rate were measured at the following points.

HVH
MS pipe
HVH

Dose rate (Sv/h)

Temperature (℃)

B3

7.4

17.8

B4

7.5

19.2

B5

8.7

19.4

B7

7.4

19.5

B11

9.7

19.2

B14

7.0

20.2

C2

6.7

19.6

C5

8.3

19.5

C6

7.7

19.4

C9

4.7

20.8

C10

5.3

21.1

C11

6.2

20.7

C11,
B14,

C10,

B13,

PLR pump

C9,

PLR pump

B12,

C8,
B11,

C7,

PLR pipe

C6,

HVH

B10,
B8,

C5,

HVH
C4,

B3,

B4,

C3,
C2,
B1,
C1,
C0, B0,

B2,

X-100B
penetration pipe

B5,
B7,
B6,

B3 to B14 (Measurement date: Apr. 10, 2015)
C2 to C6 (Measurement date: Apr. 15, 2015)
C9 to C11 (Measurement date: Apr. 16, 2015)
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117. Conditions of cable remained The route of the cable remained is shown as below.
 It was confirmed that the cable remained around the opening to access the basement will not interferewith B2 investigation.

X-6 Penetration pipe

The device stuck

Pedestal

PLR pipe

HVH（Ｄ）

X-100 B
penetration pipe

Opening to accessbasement: Part cable attached on the floor.
: Part cable is floating.
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8. Status of the investigation device stuck The status of the investigation device stuck was checked.

B14,
B13,

Right side crawler was caught ina gap at the joint of gratingplates.

B12,
B11,
グレーチング
B9,

A structure
Large wide gap(Space one step sunken)

Grating

B10,

B8,
B3,
B1,

B2,

B4,

B5,

B7,
B6,

Investigation device(End point)

B0,Investigation device stuck

A structure 13
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9. Check on the access route up to CRD rail
 It was concluded that the access route up to CRD rail is too narrow to get thedevice pass through.
Access route

B14,
B13,

A structure

B12,
B11,
グレーチング
B9,
B8,
B3,
B1,
B0,

B2,

B4,

B5,

B10,

A structure
The device
stuck

Shooting range

B7,
B6,

Investigation
device II

Access route

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10. Investigation device remained Where the device remained is as shown in the figure below.
 The investigation device remained will not interfere with B2 investigation planned to be conducted.
CRD rail
HVH
MS pipe: Access route investigated(Counterclockwise route)On counterclockwise,
dated Apr. 13.

: Access route investigated(Clockwise route)

Where the device
remained.

C11,
B14,

C10,

B13,

C9,
B12,
C8,
B11,

PLR pump

C7,

B9,

C6,

PLR pipe

B8,

C5,
B3,

C4,
C3,

HVH
Counterclockwise,
dated April 20

Where the device
remained.

C2,B1,

B2,

B5,
B4,

B7,
B6,

C1,C0,

B10,

Opening toaccessbasement

B0,

X-100B penetration pipe
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11. Summary The data on the grating around the pedestal inside Unit 1 PCV was obtained.
 Results of this investigation will be reflected on the study of construction methods
for B2 investigation to be conducted (pedestal at basement).
: B2 investigation range： B2 investigation route

X-100B
penetration
pipe

16

1FL Grating

Opening toaccessbasement

Access entrance
for workersPedestal

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16

(Reference) Second investigation device remained Due to the deterioration of the monitoring camera with radiation (assumption), the camera’s visibility
was extremely dropped to the point disable to perform a deformation check on the device at the time of
retrieving it from the vessel. Accordingly, the collection of the device to outside the reactor primarycontainment vessel was judged as risky. (*1)
PCV

Bellows part of guide pipe

*1 Judging from the facts that thedeterioration of the monitoring
camera and that there was a slight
unevenness at the bellow part ofguide pipe for inserting theinvestigation device, there is a riskthat the device might get caught
when passing though the bellows.

Guide pipe

X-100B Penetration pipe
Bldg. concrete
CRD Support beam
Device hatchmonorailMonitoring camera
To check a deformation
degree of the device Inorder to collect the device
from the grating floor.

Investigation device

1F Grating

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(Reference ) Image topics (Equipment hatch and wall outside the pedestal)
Taken from B3 Exterior status of the wall outside the pedestal
No significant damages were found on the wall outside
the pedestal .
Wall outside the pedestal

HVH

HVH

B14,
B13,

PLR pump
B12,
B11,
B9,

PLR pipe

Taken from B2

Exterior status of equipment hatch

No significant damages were found on equipment hatch.

B10,
B8,

HVH
B3,
B1,

B4,

B2,

B5,
B7,
B6,

B0,

X-100B
penetration pipe

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(Reference) Image topics (PLR pump (A))
Taken from C10

PLR pump
Pipe withsmall
diameter

MS pipePedestal opening

C11,
C10,

PLR pump (A)
C9,
C8,
C7,

PLR pump
Pipe withsmall
diameter

PLR pipe
C6,

HVH （E）

C5,

HVH (D)

C4,
C3,
C2,
C1,
C0,

X-100B Penetration pipe

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19

(Reference) Image topics (PLR pipe)
Taken from B7
・No significant damages were found on PLR pipe (heat insulation)
・Pieces of the shield of the pipe was found to be fallen off.
HVH

HVH

PLR pipe
B14,
B13,

PLR pump
B12,
B11,
B9,

PLR pipe

B10,
B8,

HVH
B3,

B1,

B4,

B2,

B5,
B7,
B6,

B0,

Approx. 20 mm
X-100B
penetration pipe
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20

(Reference) Measurement of temperature and radiation dose rate
Temperature and dose rate were measured at the following points after
conducting a review of the investigation on counterclockwise.

Measurement date: Apr. 19, 2015
Dose rate(Sv/h)

Temperature(℃)

Around B14

4.4

17.9

Around B11

5.7

18.7

Around B7

5.9

19.1

End point where thedevice remained.
(Around C3)

4.1

20.4

Pedestal opening
Pedestalopening

B14,
B13,
B12,
B11,

PLR pump
B9,

PLR pipe
B3,

C3,
C2,

B1,

B2,

B8,
B5,

B4,

B7,
B6,

B10,

C1,
C0,

B0,

X-100B
penetration pipe
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21

(Reference) Results obtained after the re-installation of measuring instruments inside
the PCV for surveillance monitoring. (1)■Overview of the re-installation of measuring instruments inside the PCV for surveillance monitoring
Measuring instruments installed inside Unit 1 PCV for surveillance monitoring were removed in order to conduct B1 investigation. Having
completed the investigation, new measuring instruments equivalent to the existing ones are newly installed on the same position where theformer ones were set.

No

Thermometer

Installation level(Under evaluation)

Indication
value
(℃ )

DC resistance (Ω)(Measuring value/ Design value(±56))

T7

OP.14500

18.1

1830 ／ 1842

T7
T6

T6

OP.14000

18.1

1845 ／ 1858

T5

T5

OP.13230

18.0

1875 ／ 1889

T4

OP.12500

17.8

1903 ／ 1917

T3

OP.11200

17.81950 ／ 1965

T2

OP.7500

18.9

2091 ／ 2102

T1OP.6330

18.92135 ／ 2146

T4
HVH-12DT3

Jet deflector
T2
T1
D/W, the bottom
OP.6180［Data taken as of 12:00, 4/23]

Newly installed thermometers

X-100B
OP.14700

D/W, 1F
GratingOP.9708

Existing thermometers［Data taken on as of 12:00, 4/23]

OP.14000

TE-1625J

24.9℃

OP.11200

TE-1625D

17.4℃【Reference]
Temperature measured at the B1 investigation (at the height of grating):

Around 17 to 20 ℃
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22(Reference) Results obtained after the re-installation of measuring instruments inside
the PCV for surveillance monitoring. (2)■ Check on the operating point of water gauge inside the PCV
D/W, 1FGrating

Water gauge(Leak sensor)■ Water gauge operating status
L7

L6
L5

・In operation ：L1～L5
・Non-operating：L6～L7

Operating points⇒ Both PCV water levels and water gauge
installation levels are currently underevaluation.

L4
L3
L2
L1

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(Reference) Summary of installation results/ Future handling of thermometers

 Installation results(1) Temperature inside PCVRegarding the thermocouple reinstalled inside the PCV, with the fact that both DC and insulation resistancevalues after inserting are found to have no problem, plus the fact that value indicated before and after thereplacement shows almost no difference in figure, it was verified that the reinstallation has been madewithout fail.

(2) Water levels inside the PCV
PCV water levels and the positioning for installing water level indicators are currently under evaluation.

 Future handling of thermometersRegarding the thermometer having installed, for the next one month or around, it will be checked
whether the device is working in accordance with the status of water injection into reactor and thecondition of outdoor temperature fluctuation, etc. And when the device was judged as acceptable formonitoring the cooling status, it will be selected as a surveillance thermometer for monitoring the cold
shutdown condition specified at Article 18, Chapter III of the implementation plan.

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24