‐‐ Site test “Investigation B1” on grating around the pedestal inside Unit 1 PCV ‐

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“Development of a technology to investigate inside the Reactor Primary Containment Vessel (PCV)”

April 13, 2015

Tokyo Electric Power Company

<Reference>

‐‐ Site test “Investigation B1” on grating around the pedestal inside Unit 1 PCV ‐

[For April 10]

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1. Investigation overview

Access points (Planned) C0, C11,

B0, ～ B18,

～

X‐100B

CRD rail

PLR pump

HVH MS pipe

PLR pipe

HVH

Pedestal Opening

B1, B2,

B3, B4, B5, B6,

B7, B8,

B9, B10, B11, B12, B13, B14, B18,

B0,

B17, B16,

B15,

C2, C3, C4, C5, C6, C7, C8, C9, C10,

C11,

C1, C0,

Counterclockwise access route

(Conducted on April 10)

Investigation device

: Access route (counterclockwise) : Access route (clockwise)

Purpose: For Unit 1, conducting an investigation in order to collect information on “the 1^st floor grating inside the Primary Containment Vessel (PCV)” from the robot inserted through X‐100B penetration pipe.

Clockwise route

Counterclockwise route

Opening to access Basement floor

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2. Access route (performance result)

Actual investigation route Original route

Fallen objects

X100B penetration pipe

B0,

B1, B2,

B3,

B5,

B6, B7,

B8, B9,

B11, B12, B14, B15,

B16, B17,

B18,

B10, B13,

B4,

Where the robot stuck

 The investigation was conducted taking on a different route as some objects were found to be fallen on the original access route planned.

 The robot was stuck on the route between B14 and B15.

Approx. 20 mm Approx. 20 mm

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3. Investigation results

No. Location Investigation results

①

Opening to access basement

floors

・B2 investigation* will be conducted next time.

TEPCO confirmed there is an opening accessible to the basement as well as no obstacles around it.

② CRD rail

・Yet to be reached at CRD rail.

・Images have been takenwith a camera facing towards CRD rail from the place where the robot reached at, which is now under evaluation.

③ On the access route

・No significant damages were found on the existing facilities.(such as HVG, PLR pipe, the wall of Pedestal)

・Information on the temperature and radiation levelshas been obtained at each investigation point.

The following information were obtained for items ① to ③ of this investigation.

* B2 investigation: Investigation on basement floor excluding the pedestal.

B10,

X‐100B Penetration

pipe

PLR pump

HVH

PLR pipe Pedestal

Opening

HVH

CRD rail

HVH

Opening to access basement floors

B0,

B1, B2,

B3, B4, B5, B6,

B7, B8,

B9, B11,

B12, B14,

B13,

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B10,

X‐100B Penetration pipe

PLR pump

HVH

Pedestal Opening

HVH

Opening to access Basement floor

B0,

B1, B2,

B3, B4, B5, B6,

B7, B8,

B9, B11,

B12, B14,

B13,

4‐1. Images (Opening to access the basement)

B４

Spot where the robot can be inserted.

With B2 investigation to be conducted next time, TEPCO confirmed there is an opening accessible to the basement as well as no obstacles around it.

Appri. 20 mm

Approx. 50 mm

PLR Pipe

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B10,

PLR pump

HVH

Opening

HVH

B0,

B1, B2,

B3, B4, B5, B6,

B7, B8,

B9, B11,

B12, B14,

B13,

PLR pipe

B7

4‐2. Images (PLR pipe)

Approx. 20 mm

・No significant damages were found on the PLP pipe (for heat retention).

・It was found that a part of the shield has been fallen off.

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B10,

PLR pump

HVH

Opening

HVH

B0,

B1, B2,

B3, B4, B5, B6,

B7, B8,

B9, B11,

B12, B14,

B13,

4‐3. Images (Equipment hatch and exterior of pedestal)

Exterior of the outer wall of the pedestal

No significant damages were found on the outer wall of the pedestal.

B３

Exterior of the equipment hatch.

No significant damages were found on the equipment hatch.

B2

Outer wall of the pedestal

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HVH（In the center at the bottom) HVH（At the edge of the bottom)

No significant damages were found on HVH (D).

B10,

PLR Pump

HVH

Opening

HVH

B0,

B1, B2,

B3, B4, B5, B6,

B7, B8,

B9, B11,

B12, B14,

B13,

B1

Approx. 20 mm Approx. 20 mm

4‐4. Images (HVH (D) )

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5. Investigation results (Temperature/ dose rate)

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

Temperature and dose rate were measured at the following points.

B10,

X‐100B Penetration

PLR pump

HVH

Opening

HVH

B0,

B1, B2,

B3, B4, B5, B6,

B7, B8,

B9, B11,

B12, B14,

B13,

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6. Investigation robot stuck on route

 Object was found to be fallen on the planned route between B 14 and B 15 where was the narrowest part of it.

 Following the procedures, the investigation continued by choosing an another route avoidable the objects.

 After that, although the robot stuck at a narrow point, it captured some images facing to the direction of CRD rail. (currently the images are under evaluation)

Actual investigation route Original route planned Where the

robot stuck B15, Existing pipe

B14, Fallen object

★

Possible cause and measures:

The robot got stuck with an existing pipe and some shut parts of the grating or uneven part at the joint, which

resulted in making the route hard to run on.

Measures to be taken are under study.

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April 2015

１０１１１２１３１４１５１６１７

Fri Sat Sun Mon Tue Wed Thu Fri

1. Investigation on counterclockwise route

2. Investigation on clockwise route

7. Schedule

Robot collection review

Under examination for the implementation period for the investigation on clockwise route.

Investigation

Dose rates were obtained below 10 Sv/h.

A knowlege was obtained that with the same amount of dose rates in “investigation on clockwise route”, the investigation camera which installed into the robot could tolerate two or three days without any problems .

As for the case of an investigation on clockwise route, the plan is currently reviewed based on the knowledge obtained above.

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Reference: Mock‐up

Spot where the robot stuck

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Reference: Mock‐up

Spot where the robot stuck

CRD rail