Asian Youth Nuclear Symposium 2022

Decommissioning of TEPCO Fukushima Dai-ich NPP

R&D status by Industry
July. 10th, 2022
International Research Institute for Nuclear Decommissioning (IRID)
Naoaki Okuzumi

This results are obtained from subsidy projects of Countermeasures for Decommissioning and Contaminated Water granted by the Ministry ofEconomy, Trade and Industry (METI).

Unauthorized copy and reproduction prohibited.
©International Research Institute for Nuclear Decommissioning

Contents

1. Introduction
2. Development of Investigation Technology for inside
Primary Containment Vessel(1) Completed investigation(2) Next Investigation
3. Technological development of fuel debris retrieval(1) Trial retrieval(2) Increasing the scale of retrieval in stages(3) Further increasing the scale of retrieval

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Contents

1. Introduction
2. Development of Investigation Technology for inside
Primary Containment Vessel(1) Completed investigation(2) Next Investigation
3. Technological development of fuel debris retrieval(1) Trial retrieval(2) Increasing the scale of retrieval in stages(3) Further increasing the scale of retrieval

3Outline of IRID
1. NameInternational Research Institute for Nuclear Decommissioning(IRID)
https://irid.or.jp/en/R&D
2. Date of Establishment
August 1, 2013

IRID
3. Membership (18 organizations)
2 Research Institutes
International
JAEA etc.
Entities
4 Manufacturers
ToshibaESS, Hitachi-GE,MHI etc.
12 Electric Utilities, etc.
TEPCO Holdings etc.
4HRD

©International Research Institute for Nuclear Decommissioning

Boiling Water Reactor (BWR)
Reactor Building 46m

SpringExternal
springApprox.10mm

RPV

Pedestal

Reactor Pressure
Vessel (RPV)

Channel
box
Tie
plate

5.5m

A-A’ Cross section

11m

Dry Well(D/W)

2F

Fuelassemblie
Water rods
Control rod
Channelbox

20m

1F

PCV: PrimaryContainment
VesselTorus
Room

Fuelcladding(ZirconiumalloyPellet

DS Pit34m

Recirculation
systemoutlet

Spent
Fuel
4F Pool(SFP)
3F

21m

46m

Fuel assemblies

PelletSupportgridOperation Floor(5F)Steam separator

Approx.
10mm

Fuelassemblies

Steam dryer
Steam outlet
nozzleControl rod

Fuel assemblies

HandleVent Pipe

9m

Approx.14cm

Fuel Assembly
Suppression
Chamber(S/C)

38m

Unit 2&3

5©International Research Institute for Nuclear Decommissioning

Contents

1. Introduction
2. Development of Investigation Technology for inside
Primary Containment Vessel(1) Completed investigation(2) Next Investigation
3. Technological development of fuel debris retrieval(1) Trial retrieval(2) Increasing the scale of retrieval in stages(3) Further increasing the scale of retrieval

6

Robot Investigation of inside of the PCVInvestigation of inside the pedestal (Unit 2)

Investigation of outside the pedestal (Unit 1)○ Remote-operated crawler robot for investigation
CrawlerDuring investigation
Additional
lighting

Winch

Rear camera and lighting
Camera for travelling throughguide pipe

Duringinvestigation

Type Ⅰ(when passing through a guide pipe)

Crawler

Front camera and lighting

Camera for travelling

CRD rail○Suspension type investigation
device (A2’ investigation)

Winch confirmation
camera (inside)

Investigation of inside the pedestal (Unit 3)

Sensor unit measuring
cameraThruster for up-and-down
U-shape type(when travelling on the floor)

Front camera

Taper

Thruster fordriving
Light

Radiation
dosimetry○Submersible Crawling Robot

Measuringcamera7©International Research Institute for Nuclear Decommissioning

Unit 2 investigation: Pedestal Floor

Pedestal floor and wall
Fuel debris? and a fuel assembly handle

A photographing
place

Bottom of the Unit 2 PCV(An overhead image)88©International Research Institute for Nuclear Decommissioning

Contents

1. Introduction
2. Development of Investigation Technology for inside
Primary Containment Vessel(1) Completed investigation(2) Next Investigation
3. Technological development of fuel debris retrieval(1) Trial retrieval(2) Increasing the scale of retrieval in stages(3) Further increasing the scale of retrieval

9Boat Type Access Device◼ A boat type access device which can move on a wide range of the water
surface in the primary containment vessel (PCV) has been developed.
Guide ringWater level during B
investigation

Estimated maximum water level

A clockwise basic route

Example: Guide ring installation• Diameter: φ25cm• Length: Approx. 1.1ｍ
• Thrust: Over 25N

Boat2Above ground floor path

Guide ringAppearance of the boat type access device

Travelling line of the device

10©International Research Institute for Nuclear Decommissioning

Boat Type Access Device (Video)

11©International Research Institute for Nuclear Decommissioning

Boat Type Access Device (Investigation inside PCV through X-2 penetration)◼ Six kinds of boat type access/investigation devices with submersible functions will be prepared for each function.
Installation items

Work flow (image flow)

Install device
Seal box device

Access/investigation
deviceGuide ring installation

Installation
cable

Waterlevel

Installation for cable entanglement
prevention

Guide ring

Deposit

Visual observation
Confirmation of PCV conditions by
pan-tilt camera

Fuel debris*

Deposit three-dimensional
shape measurement

Stabilizing
anchorDeposit three-dimensional shape wasmeasured by scanning ultrasonic range
finderMeasured by scanning
ultrasonic range finder

Deposit thickness
measurement
Measured by high output
ultrasonic sensor

Neutron flux measurement
Deposit surface measurement
by detector

Small amount of deposit
sampling
Removal of install device andseal box

Deposit thickness wasmeasured by highoutput ultrasonicsensor.

Collected bydeposit collection
device*Deposit thickness, and existence and thickness of fuel debris are uncertain, therefore, the image is described in above figure.

12©International Research Institute for Nuclear Decommissioning

Arm Type Access Device◼ The arm type access device has been made which can access the wide range
through the PCV penetration for maintenance of control rod drive
mechanism.
⚫
⚫

Total length of the arm: Approx. 22m
An investigation device up to 10kg can be loaded.

トロリ
Trolleyブーム
Boom

テレスコアーム
Telescopicarm

チルト機構
Tilt
mechanismTwo-axisjoint
2軸関節
Wand*ワンド※

アーム先端にセンサを搭載
Mounted sensor
at the tip of the arm※代わりにツールの搭載も可能*It
can be alternatively replaced a tool.

Arm type access device
13©International Research Institute for Nuclear Decommissioning

Access Route of Arm Type Device◼ The connection structure for PCV
The connection structure having thefollowing functions has been developed.
✓ Remotely approaching and attaching theexisting penetration flange.
✓ Seismic capacity of gripping mechanism✓ Confinement functions✓ Maintaining of capability that the arm canpass through.

Isolation valve

Extension pipe

X6 penetration flange

Arm enclosure

X6 penetration
ArmX6 penetration connect
structure

Isolation valve
Non-metal bellows

Gripping mechanism

Connection tube

Gripping mechanism closed

Driving mechanism
Arm cleaning anddrying mechanism
X-6 penetration connection structure

Appearance of connection structure
Unauthorized copy and reproduction prohibited.
©International Research Institute for Nuclear Decommissioning

14

Gripping mechanism opened

Arm Type Access Device (Video)
Status of UK-Japan alliance for development of the robot arm to access fuel debris

Video15©International Research Institute for Nuclear Decommissioning

Installation of Mock-up Facility (JAEA Naraha Center for
Remote Control Technology Development)
CRD

X-6 penetration+X-6 penetration
connection structure+Extension pipe

Approx.
7.7m

CRD incline rail
Approx.
5.5m

Approx.
15.8m

Appearance of the inside of the pedestal
Approx.
5.1m
Approx.
7.5m

X-6 penetration

X-6 penetration
connection structure

PedestalAppearance of mockup X-6 penetration (afterconnecting the connection structure andextension pipe)©International Research Institute for Nuclear Decommissioning

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Contents

1. Introduction
2. Development of Investigation Technology for inside
Primary Containment Vessel(1) Completed investigation(2) Next Investigation
3. Technological development of fuel debris retrieval(1) Trial retrieval(2) Increasing the scale of retrieval in stages(3) Further increasing the scale of retrieval

17Fuel Debris Trial Retrieval
The fuel debris collection device with ultrafine metal wire is equipped with the head of the arm typeaccess device.
Brush holder
TrolleyTelescopic arm

2-axis joint

Cap

Blush

BoomTilt mechanism

Blush

Ultrafine metal blush type collection device
Vacuum blood collection tube
A censor equipped with the tip of the arm* Another tool can be equipped alternatively.

Arm type access device

Suction port

Vacuum vessel type collection device

18Increasing the Scale of Fuel Debris Retrieval in Stages

Access device for fuel debris retrieval
In order to improve the payload (maximum loading capacity), a motor for the arm typeaccess device will be strengthen and the link configuration will be re-examined.
Bucket for debris fall
prevention

Sucking and grasping gripper

Collection device for pebble-like andsandy debris

Remote operated transportcarriage

Arm for retrieval

19Collection device for chip powder and core(rock-like) debris

New Opening◼ A new hole will be opened to access PCV adjacent to the X-6 penetration to further
increase the scale of fuel debris retrieval.
Equipment cell
Equipment transport carriage

New opening

Waste transport carriage

Pedestal Biological shield wall (BSW)

Shieling with BSW-PCV

X6 penetration

Equipment carry-in system

Waste carry-out system

PedestalPedestal opening20©International Research Institute for Nuclear Decommissioning

Robot Arm
Enhanced X-6
X6ペネpenetration

Access
アクセスレール
rail
Robot arm
ロボットアーム

Access rail
Robot arm

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©International Research Institute for Nuclear Decommissioning

Access Tunnel◼ The access tunnel method is required to connect a heavy-lift tunnel (approximately800 ton) with the primary containment vessel (PCV) from outside the reactor building
through the precise position control system.
◼ Delivery technology for curved heavy-lift tunnel in narrow spaces has beendeveloped with applied heavy delivery technology experienced in bridge
constructions.
Carry-in cell

Waste carry-out cell

Fuel debris retrieval cell

Maintenance cell

Fuel debris
carry-out cell

PCVAccess tunnel
A layout image of the access tunnel method
Unauthorized copy and reproduction prohibited.
©International Research Institute for Nuclear Decommissioning

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Thank you!

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