Subsidy Project of Decommissioning and Contaminated Water Management for FY2021

Development of Fuel Debris Retrieval Method(Development of Isolation Technology to Prevent
the Spread of Contamination during Retrieval andTransportation of Large Structures)
Accomplishment Report for FY2021
August 2022
International Research Institute for Nuclear Decommissioning(IRID)All rights reserved.
©International Research Institute for Nuclear Decommissioning (IRID)

No.1

Table of Contents
１． Purpose and Goals of “Development of Fuel Debris Retrieval Method(Development of isolation technology to prevent the spread ofcontamination during removal and transportation of large structures)”
２． Results and Contents of the Study on Top Access Method Conducted
as Part of Subsidy Projects
３． Project Overview
４． Implementation Schedule
５． Project Organization
６． Implementation Items of This Project
７． Summary
８． Specific Goals for Achieving the Purpose of the Project©International Research Institute for Nuclear Decommissioning1. Purpose and Goals of “Development of Fuel Debris Retrieval Method

No.2(Development of isolation technology to prevent the spread of contamination during removal andtransportation of large structures)”[Purpose of development of fuel debris retrieval method]
It is assumed that nuclear fuel has melted along with the internal structures) and exists as fuel debris in the Reactor Pressure
Vessel (RPV) and the Primary Containment Vessel (PCV) at Tokyo Electric Power Company Holdings, Inc. (TEPCO) Fukushima
Daiichi Nuclear Power Station (1F).
Assuming that the fuel debris present inside the RPV and PCV is currently in a sub-critical state, however, the plant itself is in
an unstable condition unlike it initial design since the Reactor Building (R/B), RPV and PCV, etc. have been damaged due to theaccident. For this reason, the fuel debris should be retrieved and maintained under a stable condition to prevent the spread ofradioactive materials.
Against this background, this project aims to study on the implementation of fuel debremovaleval on a further increased theretrieval scale in coordination with the engineering and project management activities undertaken by TEPCO in accordance the“Mid-and-Long-term Road-map Towards Decommissioning of TEPCO’s Fukushima Daiichi Nuclear Power Station” (hereinafter“Mid-and-Long-Term Road-map”).The development results of this project will be used in TEPCO’s engineering activities.
The purpose of this project is to smoothly carry out decommissioning and contaminated water management at 1F byimplementing projects that support technological development contributing to the decommissioning and contaminated water
management at 1F based on the Mid-and-Long-Term Road-map and the “FY2021 Decommissioning Research & Development
Plan” (Secretariat Team Meeting for Countermeasures for Decommissioning and Contaminated Water Treatment (86th), and in
addition, to make efforts to enhance the standard of science and technology in Japan.
As part of “Development of Isolation Technology to Prevent the Spread of Contamination during Retrieval and Transportationof Large Structures”, elemental technologies related to confinement of radioactive materials, which is essential to ensure thesafety of the public and workers during removal and transportation of large structures, and related to isolation for reducing theradiation exposure of the workers, will be developed for further increasing the scale of retrieval of fuel debris and internal
structures.

[Project goal]
The goal of the project is to study the implementation of fuel debris retrieval on a further increasing theretrieval scale based on the Mid-and-Long-Term Road-map.
[Duration of Project] December 2021 to March 2023 (16 months)©International Research Institute for Nuclear Decommissioning2. Results and Contents of the Study on Top Access Method Conducted as
Part of Subsidy Projects

No.3

The results of past subsidy projects and the contents of studies in the ongoing subsidy projects were examined.

(1) Results of past subsidy projects related to the top access method[Main results of studies conducted as part of Upgrading of Fundamental Technology for Retrieval of Fuel Debris
and Internal Structures (hereinafter “Fundamental Technology Upgrade”: implemented in FY2017-18)]
•

•

Top
container

An image of constructing the access route (removal of interfering objects) was created andelemental tests were conducted using structural simulations of the reactor bottom to verify thefeasibility of the removal procedure.

Container
crane

The retrieval duration (throughput) was estimated by assuming details of the procedure such as
the unit to be cut out, the shape and thickness of the portion to be cut, and the cutting method, etc.

Fuel debris
retrieval cell

Fuel debris retrieval
cell craneEquipmentloading, etc.

CRD housing
Clamp part

DSP
Well

Dedicated cask

Canister
Inside the reactor

AWJ nozzle

Removal of large structures from the reactor bottom

RPV

Shielded container
UC

PCV
Fuel debris

The Method for cutting the structures inside the PCV, collecting them in unit cans and transferring
them is quite challenging in terms of work efficiency and time required for work.
[Implementation details pertaining to Development of Technology for Further Increasing the Scale ofRetrieval of Fuel Debris and Internal Structures (hereinafter, “Further Increasing the Scale of Retrieval”:
implemented in FY2019-20)]
Verifying the feasibility of the method for transferring the structure as large as possible and then cutting
them in a separate building.
©International Research Institute for Nuclear Decommissioning2. Results and Contents of the Study on Top Access Method Conducted as
Part of Subsidy Projects

No.4(1) Results of past subsidy projects related to the top access method[Concepts of the new top access method (removing and transferring the unitized structure)]
The concept of the method for removing and transferring the unitized structure, which was studied under “Further Increasing the Scale ofRetrieval”, is indicated below.
✓ Individual structures are transferred as the unitized structure✓ The reactor core is cut into multiple units, and the lower hemispherical dome of the reactor bottom is separated in its entirety from the RPV.
✓ The shielding and air-tightness of the objects to be transferred is ensured by means of a container or access route or a combination of both.
✓ The work of finely cutting the structures that are retrieved and collecting them in a container is carried out in a building that is at a distancefrom the R/B.

[Items studied under project of “Development of Technology for Further Increasing theRetrieval Scale of Fuel Debris”]
The following items was studied in the FY2019-20 Subsidy Project
R/B(Development of Technology for Further Increasing the Retrieval Scale of 原子炉建屋
Fuel Debris).
✓Study of method for transferring (transfer route) the unitized structure.
Crane
揚重機
✓Study of the method for disassembling the reactor bottom and related
elemental tests
Passageway
連絡通路
Cutting tool
切断ツール
transportation
搬送装置
equipment

Retrievalequipment
取り出し装置[Notes]Colors indicate the following contamination levels
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone
(Study results as of end of FY2020 are listed.)

Additional
増設建屋 building

Transportation
搬送台車 cart
Collection container
回収容器
transportation
搬送装置
equipment

Auxiliary
arm
補助アーム
Lower
RPV下鏡
hemisphericaldome of RPV
Grating
insulating
グレーチングmaterial
保温材
切断ツール
Cutting
tools(把持と切断機能あり)

Connecting
接続
sleeveスリーブ

Dual lid
二重蓋(notshown in the diagram(開放中のため図示せず)
as
it is open)
Large transfer
container
大型搬出容器(Dedicatedtransfer(輸送専用容器)
container)(with holding andcutting functions)
CRDCRD.Hサポート
housing support
ビーム、ブラケット
beam
and brackets

HCU配管
HCU
piping

信号ケーブル類
SignalcablesIllustration of reactor bottom interference objects removal work

Method for transferring (transfer route) the unitized structure underconsideration©International Research Institute for Nuclear Decommissioning2. Results and Contents of the Study on Top Access Method Conducted as
Part of Subsidy Projects

No.5(2) Contents of studies conducted under the Project for “Development of Fuel Debris Retrieval Method” (hereinafter, “Retrieval Method: ongoing in FY2021-22)
Technological development of [1] Method for cutting large structures, [2] Large transfer containers, and [3] Large transportationequipment for the top access method is underway.

The Method for reducing highcontamination areas in thepassageways is being studied.
[Related to this project][1] Method for cutting large structures
Disassembling
解体装置
equipment

Crane forhandling
切断片取り
扱い揚重機
cut pieces

Disassembling
解体装置
equipment

Disassembling
解体装置
equipment

Hoisting
切断片吊り具 foraccessories
the cut pieces

ＰＣＶ上蓋
PCV upper
lid

走行

Guide
ガイド
Drive motor
駆動モータ(連絡通(outside the
台形ネジscrew
Trapezoidal
路外）
passageway)

R/B
原子炉建屋

Shroudシュラウド
ヘッドボルトhead bolt
RPV上蓋
RPVupper lidCutting
切断マニピュレータ
manipulator
Cutting
切断マニピュレータ
manipulator

切断マニ
Cutting
ピュレータ
manipulator

Crane
揚重機

Endless roller method

Separator
セパレータ

Passageway
連絡通路

スタットボルトStud
bolt

取り出し装置Retrievalequipment
Transportation
cart
搬送台車

Conceptual study is conducted on further increasing the scaleof retrieval (implemented in FY2019- 20)
Method for cutting structures other than internal structures

Additional
増設建屋 building

Trapezoidal screw drive method

Conceptual study is conducted on further increasing the scaleof retrieval (implemented in FY2019- 20)[3] Large transportation equipment
Dual lid
二重蓋(notshown in the
diagramas it is open)(開放中のため図示せず)

Connecting
接続
sleeveスリーブ

Large transfer container
大型搬出容器(Dedicatedtransfer
container)(輸送専用容器)

Method for cutting internal structures

Air-tight mechanism of the dual lid
Dual lid

Illustration of filling and cutting
Cutting [1]Filling andsolidification

Shroudシュラウド把持部
gripper（穴加工し把持）(holding by making a hole)

Shroudシュラウド

切断②
Cutting(2)

Cutting of theentirecross断面全域の切断
sectional area

ワイヤー 切断機
Wire-saw
cutter[Notes]Colors indicate the following contamination levels
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone
(Study results as of end of FY2020 are listed.)

Elemental tests are being planned on
the technological development (FY2020-21) related toensuring safety during fuel debris retrieval work.

Cutting structures from the reactor bottom
Cutting tool
切断ツール
搬送装置
transportationequipmentCollection container
回収容器
transportation
搬送装置
equipment

補助アーム
Auxiliaryarm

Auxiliary arm

Lower hemispherical
RPV下鏡
dome of RPV
Grating グレーチング
insulating
保温材
material

Cutting tools

切断ツール(with holding and(把持と切断機能あり)

cutting functions)

CRD housing
support CRD.Hサポート
beam and
ビーム、ブラケット
brackets

Φ6m

HCU配管

Geopolymer filling (Inner
diameter of container: 300mm)

Elemental tests are conducted on
further increasing the scale of retrieval (FY2019- 20)*CRGT： Control Rod Guide Tube

Fuel debris at thereactor bottom

Lower
hemisphericaldome opening

HCU piping
Collapsed CRGT*is simulated[2] Large transfer containers

7m

Cutting [2]Signal cables

信号ケーブル類

炉底部干渉物撤去作業イメージ

Elemental tests are conducted on
further increasing the scale of retrieval (FY2019- 20)

Φ7m
Conceptual study is conducted on
further increasing the scale of retrieval (implemented in FY2019- 20)©International Research Institute for Nuclear Decommissioning2. Results and Contents of the Study on Top Access Method Conducted as
Part of Subsidy Projects[Notes][Correlation between the developed items by the previous projects andthis project]

CRD
housing
CRDハウジング
クランプ部
clamp

Project of Upgrading of Fundamental Technology (implemented in FY2017-18)[Study of the Method for cutting pieces inside PCV]
➢ Implementation of elemental tests using simulated
reactor bottom structures➢ Estimation of throughput, identification of issues

AWJノズルAWJ
nozzle

炉底部の大型構造物の撤去

Removal of large
structures from thereactor bottom

sheet
隔離シート
（気密）
(air-tight)

Dual lid[Study of the Method for transferring the unitized structures]➢ Implementation of elemental tests related to disassembling
the reactor bottom➢ Conceptual study related to the large transfer containers➢ Study of the Method for criticality control until collection incontainers

Development of Technology for Fuel Debris Retrieval Method(implemented in FY2021- 22)[Development of technology for realizing the retrieval
concept]➢ Study of Method for cutting large structures➢ Study of large transfer containers (main body)➢ Study of large transportation equipment

Work
作業容器
container（遮蔽）(shielded)

G

二重蓋

R

Upper lid
上蓋
Shielding
cart
遮蔽台車

Project of Development of Technology for Further Increasing the Retrieval
Scale of Fuel Debris (implemented in FY2019- 20)

Colors indicate the following
contamination levels
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderatecontamination) zone
G (Green): Green (low contamination)
zone

Method for cutting pieces
Isolation

可動フランジMovableflangeLower
下蓋 lidNo.6

Method for cutting
大型切断工法
large structures

R

Y

Transport
cart
搬送台車

Large
transportation
大型搬送装置equipment

Large transfer
container
大型搬出容器R

Dedicatedtransport
輸送専用容器
container

G

Method for transferring unitizedlarge structures

Project of Technological Development for
Ensuring Safety (implemented in FY2020-21)[Feasibility verification of the large transfer container lid]
➢ Development and elemental tests of the air tight mechanism for the container lid➢ Study of the method for criticality control after collection in containers (during transfer)

This project[Development of Isolation Technology to Prevent the
Spread of Contamination]➢ Isolation technology development andelemental tests
Isolation
sheet
隔離シート

Items to be studied in future➢ Study of technological challenges identified during engineering and technological development etc.

©International Research Institute for Nuclear Decommissioning

Since the classification of contaminated areas is under consideration, it could be changed in the future.

2. Results and Contents of the Study on Top Access Method Conducted as
Part of Subsidy Projects[Notes]Colors indicate the following contamination levels*
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone
*Besides color, the main zones are marked as R, Y and G.

[Development results up to FY2020 (contents of studies)]

Demerits

MeritsConceptual diagram

Secondary boundary

Secondary boundary
Retrievalequipment

PassagewayConnecting
sleeveTransportationcart

R

Additionalbuilding
Dual lid
Dedicated transfer
container

Y

Retrievalequipment

Passageway

Additionalbuilding

Gate opening/closing
equipment
Connecting
sleeveGate opening/closing
equipment(Passageway method) Revision 2
Setting up partitions using work containers
Secondary boundary

Retrievalequipment

Passageway

Work container

Passageway

Additionalbuilding

A conceptual study of the methods for reducing the high contamination area inthe passageways was conducted.
(Passageway method)(Passageway method) Revision 1
Setting up partitions using gates

No.7

Gate
opening/closing
equipment

Connecting
sleeveTransportationcart

Dual lid
Dedicated transfer
container

Connecting
sleeveTransportationcart
WorkcontainerWork
container

Dual lid

Transportationcart

While transferring
the work container

Dedicated transfer
containerG・Simple retrieval procedures・ Reduction in spreading of radioactive dust ・ Reduction in spreading of radioactive dust resulting fromcutting, to the passageway due to the work containers
resulting from cutting, to the passageway
・Smaller number of equipment components,
・ Reduction in spreading of radioactive dust to thesmaller amount of waste
due to closed gatespassageway as the work containers are used fortransporting structures as well.

・ Spreading of radioactive dust resulting ・ Interference of the transport cart rail and ・ Increase in amount of secondary waste due to addition ofwork containers
from cutting, directly into the passageway
the travel drive unit when the gates close(major accumulation of radioactive dust) ・Spreading of radioactive dust to the Note; Since the underside of the work container is notpassageway
whiletransportingthe closed, it remains open momentarily when the container istransferred to the transport cart..
structures(Revision 2) is considered as the primary choice for preventing spread of contamination from radioactive dust into the passageway.

However, since the underside of the work container of (Revision 2) is not closed, contamination spreads temporarily when transferring it on
to the transport cart.
⇒ * The fuel debris retrieval is likely to continue for a prolonged period. If maintenance of the equipment, response actions in the event of emergencies, etc.
are considered, it is desirable to reduce the extent of spread of contamination as much as possible. Hence it continues to be studied as part of the
FY2021 Development of Fuel Debris Retrieval Method Project.
©International Research Institute for Nuclear Decommissioning
The status of classification of contamination areas, etc. indicated is as of FY2020. It is still under consideration and could be changed in the future.

2. Results and Contents of the Study on Top Access Method Conducted as
Part of Subsidy Projects

No.8[Development results up to FY2020 (contents of studies)]◆ Conditions concerning the work containers [(Passageway method) Revision 2: Setting up partitions using work containers][1] When the work container is separated, the reactor well side and the underside of the work container are closed simultaneously.
[2] Containers of different sizes are used depending on the work classification so as to reduce the weight of the work containers.
Work container for cutting・ Size of the work container such that it covers the wholereactor well area (large inner diameter)
・ Minimum sheet thickness considering reduction ofradiation dose from inside the reactor (thin sheet)→ Reduction in weight of work containers

Shielding the radiation dosefrom inside the reactor

Preventing spread ofcontamination
during cutting work

Work containers for transfer of structures
・ Minimum size corresponding to the structures
to be transferred (small inner diameter)
・ Sheet thickness considering reduction ofradiation dose from the structures to betransferred (thick sheet)→ Reduction in weight of work containers

When the work container isseparated, the reactor wellside and the underside of thework container are closed
simultaneously.

Approx. Φ13ｍ
Approx. Φ8ｍ
Shielding theradiation dose fromthe structures to betransferred(Internal structures,etc. have a high doserate)

During cutting (disassembling) work (Example
image)

Work container
Shielding cart

Preventing the spreadof contamination fromadhered substances

When it is transferred(common)(Example image)

During transfer work
(Example image)©International Research Institute for Nuclear Decommissioning3. Project Overview

No.9

3. 1. Collaboration with other projects
Development of safety system

Development of fuel debris retrieval method
Sharing of the status of study➢ Development of side-access method➢ Development of top-access method

Continuous
monitoring

Development of liquid/gas phasesystems, criticality control technology
Sharing of analysis needs/results
Sharing of the status of study

Fuel debris
characterization

Sharing of technological challenges
Development of a system forcontinuous monitoring inside PCV
Sharing of investigation needs/results

Internal investigation

Development of isolation technology toprevent the spread of contamination
during retrieval and transportation oflarge structures

Coordination of containing, transfer andconstruction methods

Development of isolation technology to prevent the
spread of contamination during retrieval andtransportation of large structures

Development of technology for
Investigation inside RPV・Sharing of safety scenarios
Development of technology fordetailed investigation inside PCVDevelopment of analysis and estimation
technology for characterization of fuel debris

・Coordination of work steps

Sharing of technologicalchallenges

Gradually increasing the scaleof fuel debris retrieval

Technology for ensuring safety

Development of technology for gradually
increasing the scale of fuel debris retrieval

Technological development related to ensuringsafety during fuel debris retrieval work

Containing, transfer andstorage technology

Development of technology for containing,transfer and storage of fuel debris
Coordination of containing, transfer andconstruction methods

Solid waste
Research and development related totreatment and disposal of solid waste

In this project, joint meetings will be conducted as required in coordination with the above-mentioned projects.
©International Research Institute for Nuclear Decommissioning3. Project Overview

No.10

3. 2 Development items involving solicitation information of subsidized projects andimplementation policy
Development items involving
solicitation information ofsubsidized projects

Implementation policy

1) Development of isolation
technology to prevent the
spread of contamination during
removal and transportation oflarge structures

In order to enhance the throughput of retrieving fuel debris and internal structures using the
top access method, development related to the method for transferring large unitized
structures is being carried out since FY2019. The method for cutting the large unitized reactor
internal as far as possible, pulling the cut structures up to the Reactor Building (R/B) operation
floor, and transferring them to the additional building using large transport equipment, is being
studied.
Since it is necessary to plan in such a way that the passageway from the R/B operation floor
to the additional building does not get contaminated as far as possible, in order to confine
radioactive materials, and reduce the radiation exposure of the workers, the concept of themethod for covering the contaminated structures by means of work containers during cutting
work inside the reactor and while transferring the cut structures up to the additional building, or
the method for preventing spread of radioactive materials to the passageway by providing an
isolation mechanism when the work container is transferred from inside the reactor to the R/B
operation floor, is being studied.
In order to crystalized measures to prevent the spread of contamination, the contaminatedmaterials generated as a result of work, the routes where these materials spread, etc. will be
put together, and after clearly specifying the contaminated area class required in thepassageways, technological development of equipment, operation methods, etc. concerning
the isolation mechanism for preventing the spread of contamination will be carried out.

©International Research Institute for Nuclear Decommissioning3. Project overview

Development of isolation technology to preventthe spread of contamination during retrieval andtransportation of large structures (This project)

3. 3 Purpose of this project

No.11

Development of fuel debris retrieval method(FY2021 to FY2022)

The following figure is an image illustrating the retrieval method using isolation technology such as using work containers andisolation sheets with shielding function, etc., in order to reduce the extent of contamination inside the passageways.
A structure that can co-exist with the large transfer containers and dual lid that are being currently developed, will be studied.
Isolation technology to prevent the spread of contamination (This project) → Development of isolation technology such as isolation sheet, etc.
for preventing the spread of contamination from the underside of the work container (Reducing the contamination level inside the passageways,
reducing the radiation exposure of workers, enhancing the operability of maintenance of cranes)GWork
container(Shielded)

Isolation
sheet(air-tight)

R

Y
Isolation
sheet

Shielding
遮蔽台車 cart

Method for
cutting large
structures

R

Transportation
cart搬送台車

Largetransportationequipment

R

Large transfer
containers

Image showing confinement bymeans of isolation sheet[Notes]Colors indicate the following contaminationlevels*R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination)zone
G (Green): Green (low contamination) zone
*Besides color, the main zones are marked as R,
Y and G, and the red zone is marked with a redborder.

G

Image showing reduction in contamination inside the passageways when work containers are used.
©International Research Institute for Nuclear Decommissioning

Since the classification of contaminated areas is under consideration, it could be changed in the future.

3. Project overview

No.12

3. 4 The points of concerns while executing this project
The points of concerns while executing the project are described below.
[The points of concerns]
To proceed with the development, the following points of concerns are considered forhandling efficiency and maintenance methods of remotely operated equipment

・Remote-operated maintenance should be principle because the equipment will be
installed in high radiation areas.
・The contamination of the equipment and the required decontamination should be taken
into consideration.
・The work area available for maintenance work is limited.
・Waste generated during maintenance work needs to be minimized as much as possible.
・Installation and handling of criticality monitoring equipment needs to be considered.

©International Research Institute for Nuclear Decommissioning4. Implementation Schedule

No.13: Planned: Actual

FY2021

Study items
4

Major milestones

5

6

7

8

9

10

11

FY2022
12

1

2

3

4

5

6

Interim Report
▼

7

8

9

10

11

Interim Report
▼

12

1

2

3

Final report▼

1. Conceptual study
2. Planning ofelemental tests
3. Test preparation/
Test manufacturingof testing
apparatus

4. Elemental tests
5. Summary

Remarks©International Research Institute for Nuclear Decommissioning5. Project Organization
International Research Institute for
Nuclear Decommissioning (IRID)➢ Coordination of overall planning and technology
management➢ Coordination of technology administration including
technology development progress management

Hitachi-GE Nuclear Energy, Ltd.
[Elemental test, technical development](1) Development of isolation technology to prevent the
spread of contamination during retrieval andtransportation of large structures[Sub-contracting details]
・ Technological development related to isolation
technology to prevent the spread of contamination(Toko Corporation)
Sub-contractor for the following is TBD
・ Designing assistance related to isolation technology
for preventing the spread of contamination(Planned)

No.14

Tokyo Electric Power Company Holdings, Inc.
➢ Various coordination for site application

Project teams to cooperate for technological development
Development of Technology for Detailed
Investigation inside PCV (Field validation of
the technology for detailed internal
investigation using X-6 penetration)

Development of Technology Supporting
Integrated Management of Decommissioningat Fukushima Daiichi Nuclear Power Station(Development of a system for continuous
monitoring inside PCV)

Development of Technology for Detailed
Investigation inside PCV(On-site Demonstration of Technology for
Detailed Internal Investigation Considering
Deposit Measures)

Development of Technology for Further
Increasing the Scale of Retrieval of Fuel
Debris and Reactor Internals(Technological development related toensuring safety during fuel debris retrieval)

Development of Technology for Investigation
inside RPVDevelopment of fuel debris retrieval method

Development of technology for gradually
increasing the retrieval scale of fuel debris

Development of safety systems (liquid/gas
phase systems, criticality control technology)

Research and development for treatment anddisposal of solid waste

Development of analysis and estimation
technology for characterization of fuel debris

Development of technology for containing,transfer and storage of fuel debris©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.15
Solicitation information details are as below.

1) Development of isolation technology to prevent the spread of contamination
In order to enhance the throughput of retrieving fuel debris and reactor internal structures using the top accessmethod, development concerning the method for transferring the large unitized structure is being carried out
since FY2019. As part of this, the method for cutting the large unitized reactor internal as far as possible, pullingthe cut structures up to the R/B operation floor, and transferring them to the additional building using largetransport equipment, is being studied. It is necessary to plan in such a way that the passageways from the R/B
operation floor to the additional building do not get contaminated as far as possible, in order to confine
radioactive materials, and reduce the radiation exposure of the workers. Hence the concept of the method forcovering the contaminated structures by means of work containers when the structures are cut inside the reactor
and while they are transferred up to the additional building, or the method for preventing spread of radioactive
materials to the passageways by providing an isolation mechanism when the work container is transferred frominside the reactor to the R/B operation floor, is being studied.
During this project, in order to implement these measures to prevent the spread of contamination, thecontaminated materials generated as a result of work, the routes where these materials spread, etc. will be put
together, and after clearly specifying the contaminated area class required in the passageways, technologicaldevelopment of equipment, operation methods, etc. concerning the isolation mechanism for preventing the
spread of contamination will be carried out. At the time of development, evaluation and selection will be
performed from the perspective of confinement performance, certainty and operability of remote operations,robustness and durability, of inspection and maintenance, etc. and the most appropriate technology will be
studied. Also,on-site applicability will be evaluated by conducting elemental tests with the help of a simulated
facility that use the studied technology.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.16

1) Development of isolation technology to prevent the spread of contamination[Issues]• There is a risk of spreading contamination throughout the passageways if the passageways are
airtight.
• It is necessary to prevent the spread of contamination considering on-site work efficiency of fueldebris retrieval work.

[Implementation details]• The contaminated materials generated from fuel debris retrieval work and the routes where thesematerials spread, etc. will be clarified, and the contaminated area class required in the passageways
will be clearly specified.
• The methods and procedures for confining contaminated materials during retrieval and transportationof large structures will be studied.
• Isolation mechanism for preventing the spread of contamination will be evaluated and selected fromthe perspective of confinement performance, certainty and workability of remote operations,robustness and durability, efficiency of inspection and maintenance, etc. and the most appropriatetechnology will be studied.
• On-site applicability of the technologies studied will be evaluated by conducting elemental tests using
a simulated test facility to verify manufacturing efficiency, operability of collection into the equipment,
air-tightness, etc.

[Expected outcome]• Presentation of the method for preventing spread of contamination while transporting contaminatedlarge structures.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.171) Development of isolation technology to prevent the spread of contamination[Classification of the contaminated area classifications required in the passageways]◆ Objective of the condition of area inside the passageways● During fuel debris retrieval work
[1] Reduction of public exposure
・ Reduction of dose rate at the site boundary
・ Prevention of leakage of radioactive dust into the environment[2] Reduction of exposure of workers
・ Remote operation/automation
Reduction of dose rate at the site boundary（Passageway + Work container shielding)

Prevention of leakage of radioactive dust
into the environment（Passageways + Confinement of work
containers)

Building cover Large crane● During maintenance and inspection work
[1] Reduction of public exposure
・ Reduction of dose rate at the site boundary
・ Prevention of leakage of radioactive dust into the environment[2] Reduction of exposure of workers
Changes to be made during this development
・ Remote operation/automation
・ Improvement in work environment: Direct maintenance by workers
can be expected by preventing spread of contamination inside thepassageways. (Stationary equipment inside the passageways,
such as large cranes, etc.)

Reduction of dose rate
inside the passageways(Shielding by shielding
cart)

G

Passageway

Transportation
cart

Work
container

Shielding cart

R

Y

Prevention of leakageof radioactive dust
inside the passageways(Closing of the reactor
well side partition)Work
container side
partition[Notes]Colors indicate the following contamination levels*
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone
*Besides color, the main zones are marked as R, Y and G, and the
red zone is marked with a red border.

Reduction in contamination of the innersurface inside the passageways

Large craneG
Y

Shielding cart
Reactor wellside partition

Additional building

Additional building

R

R
G

G
Reactor Building

During fuel debris retrieval work

Reactor Building

During maintenance and inspection work

Since the classification of contaminated areas is under consideration, it could be changed in the future.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.18

1) Development of isolation technology to prevent the spread of contamination[Concept of confinement of contaminants during removal and transportation of large structures]◆ Confinement by means of isolation mechanism

Reactor internal
structures

While lifting up
the work container

LeakageTransportation cart

Leakageprevention

Isolationmechanism

Transportation
cart(Isolation sheet, etc.)* Since the lower end of the work
container is not closed, it remains open
temporarily at the time of transferring
onto the transportation cart.

* Preventing spread of contamination fromthe structures inside large work
containers, and preventing the spreadof contamination from inside the reactor©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project
No.191) Development of isolation technology to prevent the spread of contamination[Study of the most appropriate technology related to the isolation mechanism]◆ Comparison of the method for closing the underside of the work container at the time of separating the work container〇: Good ×: Unacceptable(Results of primary comparison)
No

項目
Item

Welding
type
Trap type
Shatter-proof
type
接合方式
トラップ方式
飛散防止方式
Isolationsheet
Air curtain
Surfacepainting
隔離シート
エアーカーテン
表面塗布• Air-tight lids are installed on the• Air-tight gates are provided on the • A middle portion of a cylindrical • Air inlet and outlet ports are • The source of contamination
container side as well as the reactor well ・容器側と原子炉ウェル側の両方に気・容器側と接続先である原子炉ウェル
provided on the container side
container side as well as the reactor ・容器側と原子炉ウエル側を連結した
side, to which the container issheet that connects the ・容器側と原子炉ウエル側の両方に空on the surface of thewell side, and opening/closing isand the reactor well side such ・構造物表面の汚染源を塗料等により側の両方に気密性の蓋を設け、相互connected, and opening and closing is 密性のゲートを設け、相互のゲートを
container side and the reactor 気の吹出口と吸込口を相対させてエ
structures is solidified andperformed by sliding the container 円筒状のシート類において、中央部を
performedbyrotating
thecontainerin
itsthat the ports face each other 固めて剥離、飛散を防止の蓋を接触・密着させた状態のまま一接触・密着させた状態のままでスライ
well
side
is
squeezed
andpeeled off using paint, etc. towhile both gates are in contact and 絞り込み接合・切断する。
entirety while both lids are in contact andアーカーテンを形成し切り離す。
to form an air curtain and theclosely adhered to each other.
closely adhered to each other.
体で旋回することで開閉する。
ドして開閉する。
welded/cut.
prevent scattering.
container is then separated.
Doubledoor
ダブルドアOpening/closing
type
開閉方式
Double gate
ダブルゲートSpray
スプレイ
painting
塗布
Container

1 概要
OutlineContainer

Double gate
Joint
接合

Air
outlet
吹出口
port
Air curtainAir
inlet port
吸込口

隔離シートsheet
Isolation

Confining
efficiency
閉じ込め性
2 Gas phase
・気相(粒子)(particles)〇
・気相（粒子）の閉じ込めは可能• Gas phase (particles)

can be confined×• Leakage of・ゲート開時contaminantsの側面からfrom the sidesの汚染物質
when thegates areのリーク〇・気相（粒子）の閉じ込めは可能• Gas phase (particles)

can be confined

openedConfinement
閉じ込め性〇
efficiency
3 ・液相(水滴した• Can be collected on
Liquid phase (dripping ・容器側の蓋で受けは可能
of water droplets)
たり)
container side lid

Presence of
取り扱い時の4 interferences
干渉有無
while handling×• Interferes with
・開動作時に、
the reactor
原子炉ウエルwell side whileと干渉
opening〇
the ・容器側ゲートで受けは可能• Can be collected oncontainer side gate

Interference
withthereactor wellInterferes withthe container
for preventing
spreadofcontamination

×• It is difficult to completely confine・気相（粒子）を完全に閉じ込めること×
the gas phase (particles)
は困難• It is difficult to properly paint the• According to the JPDR dismantling ・炉内構造物の内面、隙間を確実に塗・JPDR解体実地試験（実績）ではエ
inner surfaces and crevices of the
field test (results), concentration
布することは困難
reactor internal structures.
アーカーテン内外の空気中濃度比約
ratio in the air on both sides of the
1/30*1)
air curtain was approx. 1/30*1.

〇
××
the ・容器側の下面シートで受けは可能•
Can be collected on the ・水滴の受けは困難• It is difficult to collect the water ・表面の水滴への対処に課題あり• Dealing with water droplets on thecontainer side underside sheet
dropletssurface is a challenge〇• Space is secured on the・連絡通路下面に空間確保
underside of the passageway〇• Space is secured on the・連絡通路下面に空間確保
underside of thepassageway〇• Space is secured on the・連絡通路下面に空間確保
underside of the passageway－(Opening / closing is not(開閉不要)
required)

Opening of double doors

Whether or not ××x
switching of• Both lids needs to match in size ・相互のゲートは同一径で合わせる必• Both gates need to match in
寸法の異なる〇〇
work containers ・相互の蓋は同一寸法、形状を合わせand shape.
size.
• The inlet and outlet ports are －•Sheetsofdifferentsizes
can
5 作業容器の切る必要あり。
・径の異なるシートを積層して対応（次・容器側の寸法に合わせて吹出口／
of different• Everything including the lid on 要あり。
(Opening / closing is not• Everything including the gate
provided in accordance with (開閉不要)
belayered(example 吸込口を配置
sizes is
り替え可否
・原子炉ウエル側蓋を含めた全取り換
・原子炉ウエル側ゲートを含めた全取
紙に一例）
on
the
reactor
well
side
needs
the
reactor
well
side
needs
to
required)thecontainerside
dimensions
possible
provided
on
the
next
page)
to be replaced.

be replaced.
えが必要

Conclusion ×
6 結論

り換えが必要×〇××

Note *1) Source: Journal of the Atomic Energy Society of Japan, Volume 38, Issue No. 7 (1996) “Results and Outline of JPDR Dismantling Demonstration Project”

The isolation sheet was selected for primary comparison. Under review upon further addition to the evaluation axis (durability, maintenance efficiency, etc).
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.20

1) Development of isolation technology to prevent the spread of contamination[Study of the most appropriate technology related to the isolation mechanism]◆ Method for closing the underside of the work container at the time of separating the work container(Additional explanation related to isolation sheets)[1] Highly flexible confinement method that can be applied to containers of different sizes[2] Simple methods (sheet-like material, etc.) can be applied as it is used inside the passageways (primary boundary).
→ Development of confinement method using sheet-like material (isolation sheet)

Results of past subsidy projects

FY2015 - FY2016 Subsidy Projects**

Elemental tests of isolation sheets that enclose the contaminatedstructures(Study of materials, manufacturing efficiency of large sheets, etc.)

1/4 scale model test for every work step
(Application of sheets for preventing spread of contamination)

Zipper closing part

Simple cylinder made of polyurethane sheet

Application of results

FY2014 Subsidy Projects*

Transfer container

Development ofisolation sheets
considering
combination withthe work container

New operation floor surface
Simple cylinder made of composite sheet (prototype 1)***
DSP lifter***

Illustration of transfer using sheet for
preventing spread of contamination
Bellows like sheet made of composite sheet (prototype 1)***DSP： equipment storage pool

Illustration of
detachment of thezipper closure©International Research Institute for Nuclear Decommissioning*FY2014 Subsidy Project: Subsidy Project of Decommissioning and Contaminated Water Management in the FY2013 Supplementary Budget “Development of technology for retrieval of fuel debris and reactor internal structures”**FY2015 Subsidy Project： Subsidy Project of Decommissioning and Contaminated Water Management in the FY2014 Supplementary Budget “Development of fundamental technology for retrieval of fuel debris and reactor internal structures”

6. Implementation Items of This Project

No.211) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆ Study of procedures for confinement using isolation sheets
Work container: Inner
diameter approx. 13m

Isolation
sheet baseTransportation cart

[1] While using work containerWork
container

Isolation sheet

Welding equipment

Isolation sheet[2] While lifting up the work container[3] Isolation sheet squeezing, welding,cutting/moving the work container

Work container
Shielding cart

Transportation cart

④ Moving of the transportation cart

Transportation cart

Isolation sheet

Isolation sheet

Isolation sheet

Welding

Cutting⑤ Transfer of work container* The above-mentioned procedures including the procedures forcollecting the structures in large transfer containers, the method
for replacing the isolation sheet, etc. are being crystallized.

Lifting up

Closing the underside of the work container with inner diameter approx. 13m©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.22[Notes]Colors indicate the following contamination levels*
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone
*Besides color, the main zones are marked as R,
Y and G, and the red zone is marked with a redborder.

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆ Overview of work container

The work container being studied as part of the Project for Development of Fuel Debris Retrieval Method is shown below.
The use of containers of different sizes depending on the work classification so as to reduce the weight of the work containers, is being studied.

Table: Functional requirements of the work container in accordance with the contents of work
Functional
requirements

Work
Shielding

While cutting

While transferring

Must be able to mount large disassembling equipment for cutting work

Must be able to mount a crane that can place the structures in thework container

Must be able to shield the radiation dose from inside the reactor
during cutting work

Must be able to shield the structures placed inside the work container

If the work containers are used in common, they must be extremely large and heavy. Hence different work containers will be used dependingon the work classification.

Work container for cutting

G

GWork container

Illustration of
installing thework
container

Remarks

Work container for transfer of structures
Work container

Y

Crane

Shielding cart
Shielding cart

R

Y
R

Transportation
cart

Transportation
cart

Disassembling
equipment

The large equipment for cutting can be installed and radiation dosefrom inside the reactor during cutting can be shielded.

A crane that are stored in the work containers can be installed, andthe structures stored inside the work containers can be shielded.

©International Research Institute for Nuclear Decommissioning

Since the classification of contaminated areas is under consideration, it could be changed in the future.

6. Implementation Items of This Project

No.23

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆ Example of using different work containers
While lifting up reactor internal structures or the reactor bottom part, the work container is installed on the surface of the RPV flange,
considering streamlining of shielding and the lifting range of the crane.

[Notes]Since the inside of the work container isred (high contamination) zone, it is marked
with red color.
(This page mainly consists of explanation
related to work containers. Hence
considering visibility, contaminated areas
other than the work container have notbeen marked.)

Structure

In the reactor well

Reactor internal structures

Reactor bottom part

Work container
installation location

On the operation floor

On the RPV flange surface

On the RPV flange surface

Work container

Work container

Illustration of
installing work
container

Work container

Sectionto be removed

R
Used while removing the PCV head,
RPV head insulating material, RPV
headRemarks

Used while removing the reactor core

Table Using different work containers in accordance with the structures (Current proposal*)
Structure

Work container
installation location

While cutting

While transferring

In the reactor wellOn the operation floor

Work container A

Work container B

Reactor internal structures

On the RPV flange
surfaceWork container C

Reactor bottom part

Sectionto be removed

Sectionto be removed

Work container D
Work container E

Since the weight of the reactor bottom
part is approx. 250ton, and needs to belifted 20m or more, a larger crane isused for the reactor bottom part.
* With regards to using different work containers, after studying
the series of work steps involved, a study will be conducted
once again to check whether or not the no. of containers canbe reduced by streamlining the work steps.
The work containers A to E in the table on the left are
assumed to be different in terms of their size, shielding
thickness, etc.
(Under detailed examination)©International Research Institute for Nuclear Decommissioning

Since the classification of contaminated areas is under consideration, it could be changed in the future.

6. Implementation Items of This Project

No.24

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆Removal of shield plug
The proposed shield plug removal steps being studied under the Project for Development of Fuel Debris Retrieval Method are indicated below.

1. Carrying-in the shield plug disassembling equipment
Shielding cart

2. Lifting up the shield plug

Shield plugdisassembling
equipment

Shield plug

Transportation cart

Preventing spread ofcontamination using
sheets, etc.

3. Moving the transportation cart under the plug andloading the plug

4. Moving the shield plug disassembling equipment,
the transportation cart and the shielding cart as a single unit

Shielding cart

Transportation cart
©International Research Institute for Nuclear Decommissioning* Cases of performing work while pouring water or cases using work containers and isolation sheets are being studied for preventing dispersion of dust.

No.25

6. Implementation Items of This Project1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆ Outline of isolation sheet base installation work
After removing the shield plug, the base for installing the isolation sheet is installed.
Passageway

Isolation sheet baseA

A
Isolation sheet
base

C

R/B

C

View B - B Water seal of theisolation sheet baseLayout drawing

Transportation cart rail

Isolation sheet base

Passagewaywater seal

Isolation sheet welding/cutting equipment
B

Outer peripheral cover

Water seal of the isolation sheet base

Cross-section C - C

The outer periphery of
the isolation sheet baseis sealed by installing it
inside the water seal

B

View A - A(Cross section of the center of the well)©International Research Institute for Nuclear Decommissioning*This work is carried out before removing the plug, if the shield plug will be removed using the work container. (Under detailed examination)

6. Implementation Items of This Project

No.26

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during removal and transportation of large structures]◆ Illustration of the isolation sheet installation
Isolation sheet

Isolation sheet base

A
C

A

C

Work container
for cutting

View B - B Water seal of theisolation sheet baseLayout drawing

Isolation sheet baseIsolation sheet (*)
Part occupied by isolation sheet

B

View C - C

Water seal of theisolation sheet base(*) Installation image
Since it is actually pulled by negative pressure, it gets pulled inside the reactor.

B

View A - A(Cross section of the center of the well)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.27

1) Development of isolation technology to prevent the spread of contamination[Notes]Colors indicate the following contaminationlevels*R (Red): Red (high contamination) zone
Y
(Yellow):
Yellow(moderatecontamination) zone
G (Green): Green (low contamination) zone
*Besides color, the main zones are marked
as R, Y and G, and the red zone is marked
with a red border.

[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆Dryer removal work steps (1/3) *Pre-condition: The cutting work has been completed by means of the disassembling
equipment and work container for cutting. Changes in the contamination zones in association with transfer procedures
and transfer work are indicated below, with the dryer removal (transfer) work steps as an example.

1. Carrying-in work containers for transferring structures

G

2. Transporting the work containers and moving the shielding cart

GWork container

作業容器
Work
container

作業容器

Isolation sheet baseY

遮蔽台車
Shielding
cart

搬送台車

Transportation cart

Additional building

Y

Shielding cart 遮蔽台車

Isolation
隔離シート
sheet

搬送台車

Transportation cart

Isolation
隔離シート
sheet

R

R
G

G

作業容器

Isolation sheet

搬送台車

Transportation cart

作業容器
Work container

Work container Y

Shielding cart
遮蔽台車

Y
Isolation
隔離シート
sheet

搬送台車
Transportation
cart

Isolation
隔離シート
sheet

Isolation
sheet cutting

R
R

G

4. Suspending the work container and cutting the isolation sheeton the underside of the work container

Underside of the work container
sealed with isolation sheet

遮蔽台車
Shielding cart

Largetransfer
container
大型輸送容器大型輸送容器

3. Retreating of transportation cart

G

R

Large transfer containers

R

Large
transfer
container
大型輸送容器G

R

R
大型輸送容器Largetransfer
container

G©International Research Institute for Nuclear Decommissioning

Since the classification of contaminated areas is under consideration, it could be changed in the future.

6. Implementation Items of This Project

No.28

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆Dryer removal work steps (2/3)[Notes]Colors indicate the following contamination levels*
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone
*Besides color, the main zones are marked as R,
Y and G, and the red zone is marked with a redborder.

6. Welding and cutting the isolation sheet

5. Removing the dryer
G

G

Dryer

作業容器

作業容器

Work container

Work container

Shielding cart
遮蔽台車

Isolation sheet

搬送台車
Transportation
cart

Y

遮蔽台車
Shielding cart

Isolation sheet

Isolation
隔離シート
sheet

搬送台車
Transportation
cart

R

Large
大型輸送容器transfer
containertransfer
container

作業容器
Work container

作業容器

Work container

Y
搬送台車

Shielding cart
遮蔽台車

Isolation
隔離シート
sheet

搬送台車
Transportation
cart

Y
Isolation
隔離シート
sheet

R

R
R

G

8. Suspending the work container, andpositioning the dryer
G

GTransportation
cart

大型輸送容器Large

G

7. Moving the transportation cart

遮蔽台車
Shielding cart

Isolation
隔離シート
sheet

R

R
R

Y

Large
transfer
container

R

大型輸送容器Large
大型輸送容器transfer
container

G

G©International Research Institute for Nuclear Decommissioning

Since the classification of contaminated areas is under consideration, it could be changed in the future.

6. Implementation Items of This Project

No.29

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation oflarge structures]◆Dryer removal work steps (3/3)[Notes]Colors indicate the following
contamination levels*
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderatecontamination) zone
G (Green): Green (low contamination)
zone*Besides color, the main zones aremarked as R, Y and G, and the red zone
is marked with a red border.

9. Transporting the work containers and moving the shielding cart
G
作業容器

Shielding
cart

Work
container

遮蔽台車

Y
搬送台車
Transportation
cart

Isolation
隔離シート
sheet

R
R

大型輸送容器Largetransfer
containerG

Since the classification of contaminated areas is under consideration, it could be changed in the©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.30

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆ Outline of the RPV head removal work
Images illustrating transfer of the RPV head while ensuring shielding and air-tightness using work containers, which is
being studied under the Project for Development of Fuel Debris Retrieval Method, are given below.
1. Carrying-in the work container for cutting

Overhead slewing
craneInstallation ofwork container
for cutting

2. Cutting the RPV head bolt

Transportation cart

3. Retreating of the work container for cutting, carrying-in the work
container for transfer of structures*Installation of work container fortransferring structures(Carried-in after the work container
for cutting retreats*)

4. Transferring the RPV head
RPV head

Work container fortransfer of structures

Isolation sheet installation
Retreating of overhead slewing
crane disassembling equipment andwork container for cutting*: The work container for cutting and the work container for transferring structures are shown in the image at the same time,©International Research Institute for Nuclear Decommissioning
however, in reality, the work container for transfer of structures is carried-in after the work container for cutting retreats towards the additional building.

6. Implementation Items of This Project

No.31

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆RPV head removal work steps (1/6) *Pre-condition： The work of cutting the RPV head bolt has been completed,and the work container for cutting has retreated.
Gate

A
Work
container

Welding andcuttingequipment

Existing isolation sheet
Existing isolation sheet

Shielding
cart
Transportation
cart

Water seal of the isolation sheet baseView A

Existing isolation sheet

Illustration of the isolation sheet in Step 1
1. Carrying-in work containers for transferring structures
A

New isolation sheet
Work container

New isolation
sheet

Work
container

New isolation sheet
Welding andcutting equipment

Shielding
cart
Transportation
cart
Existing
isolation sheet

Contaminated area

Row B seat
Row A seat
(Inner periphery)

Existing isolation sheet

Existing isolation sheet

2. Transporting the work containers andmoving the shielding cart

Row A seat

View A

Illustration of the isolation sheet in Step 2©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.32

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆ RPV head removal work steps (2/6)
New isolation sheet

A
Work container

New isolation
sheet

Work container

Shieldingcart

New isolation sheet
Welding andcutting equipment

Existing
isolation sheet
Row B seat

Contaminated area

Transportation cart
Row A seat
(Inner periphery)

Existing isolation
sheet

Row A seat
Existing isolation sheet

3. Retreating of the transportation cart

View A

Illustration of the isolation sheet in Step 3

Work container

A

Existing
isolation sheet

New isolation
sheet
Existing
isolation sheet

Welding andcutting equipment

Row B seat
(Outer periphery)Contaminated area

A seat for the hook is installed on the wall surface of
the water seal (outer periphery)→ Allowing the flexible structure work arm, etc. toaccess from the outer periphery and hitching it on to
the row B seat (outer periphery) is being studied.

4. Suspending the work container and installing the new isolation sheet

Row A seatRow B seat

View A

Illustration of the isolation sheet in Step 4©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.33

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during retrieval and transportation of large structures]◆ RPV head removal work steps (3/6)
A

New isolation sheet
CuttingWork container

Cutting

Welding andcutting equipment

Retrievalequipment

Row A seat

Contaminated area

Row B seat
Cutting on the inside of the work container (cutting position, etc. is being studied)

5. Cutting the existing isolation sheet and suspending the retrieval
equipment

View A
Illustration of the isolation sheet in Step 5AWork container

RPV head

Welding andcutting equipment

Row A seat
Contaminated area

6. Removing the RPV head

Row B seat

View A

Illustration of the isolation sheet in Step 6©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.34

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during removal and transportation of large structures]◆ RPV head removal work steps (4/6)
New isolation sheet

A
Existing isolation sheet
Work container
Welding andcutting equipment

Row A seat

7. Lifting up the work container◼ Allowing the remotely operated equipment
to access from the outer periphery andremoving the hitch on the row A seat (outer
periphery) is being studied.

Row B seat

View A◼ The A row seat part is collected by drawing
it inside the new isolation sheet.

Illustration of the isolation sheet in Step 7©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.35

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during removal and transportation of large structures]◆ RPV head removal work steps (5/6)
New isolation sheet

Welding andcuttingequipment(Moved to theright side)

Existing
isolation
sheet

Row A seat

Squeezing,welding andcuttingA

Row B seat

New isolation sheet

View A
Welding and cutting equipment

8. Squeezing, welding and cutting the new isolation sheet◼ Allowing the remotely operated equipment
to access from the outer periphery andchanging the position of the hitch to therow B seat (inner periphery) is being studied.

Row B seat

View A

Illustration of the isolation sheet in Step 8©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.36

1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during removal and transportation of large structures]◆ RPV head removal work steps (6/6)
Existing isolation sheet
A
Existing
isolation sheet

Work container
Welding andcuttingequipment

Shielding cart

New isolation
sheet

Transportation cart

Closing lid

Row B seat

View A

9. Moving the transportation cart, andsuspending the work container

Illustration of the isolation sheet in Step 9AWork container

New isolation sheet
Row A seat

Welding and cutting equipment
Shielding cart

Closing lid

Transportation cart
Row B seat
(Inner periphery)

Row B seat

Contaminated area

A View
10. Transporting the work containers andmoving the shielding cart

Illustration of the isolation sheet in Step 10©International Research Institute for Nuclear Decommissioning

[Notes]
Colors indicate the following contamination levels*
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone
*Besides color, the main zones are marked as R, Y
and G, and the red zone is marked with a red border.

No.37

6. Implementation Items of This Project1) Development of isolation technology to prevent the spread of contamination[Study of the procedures for confinement of contaminants during removal and transportation of large structures]◆ Study on handling the isolation sheet (used isolation sheet) after retrieving the structures
The isolation sheet is planned to be used mainly [1] when the structures are retrieved and [2] when the structures are collected in large transfer
containers, as shown in the figure below. Handling of used isolation sheets is being studied. The status of the study is indicated below.
[1] When the structures are removed: The cut isolation sheet is placed into the work container along with the structures using the removal equipment.
[2] When the structures are collected: The used isolation sheet mentioned in [1] above, the isolation sheet at the time of collection, and the structures
are all placed into the large transfer containers.
（
Ｙ→ After being transferred from the additional building, when the structures are removed from the large transfer containers for storage, etc. in other）buildings, the isolation sheets are removed as well and are disposed off as waste.

G

Work
container[1] When the structures
are removed.

Work container
R

Isolation
sheet baseY[2] When the
structures are stored.

遮蔽台車 cart
ShieldingR

Lifting up thework container

Isolation
sheet

隔離シート収納部Transportation
搬送台車
cart

Structures are
stored in largetransfer
containers

R
Dual lid (open)
水シール

Before collecting
the structures

Large transfer
containers

G

Isolation sheet
Squeezing,welding and cutting

After collecting thestructures(Work container separation)

Illustration of the isolation sheet when
the structures are stored.
(Note) [1] After retrieving the structures, the new installation sheet(for separation) is installed on the outer periphery of the work
container in the additionally built building.

©International Research Institute for Nuclear Decommissioning

Since the classification of contaminated areas is under consideration, it could be changed in the future.

6. Implementation Items of This Project

No.38

1) Development of isolation technology to prevent the spread of contamination[Study related to isolation sheets]
The following studies are being conducted under this project[1] Study of the isolation sheet handling step(All the steps are being studied under the Project of Development of Fuel Debris Retrieval Method)→ Steps involved in the method related to isolation sheets is being studied. (Refer to No. 21 - 37)
The required specifications (strength and efficiency of cutting, etc.) of the isolation sheet are studied based on
the steps.
[2] Evaluation of the isolation sheet material and the physical properties, study of isolation sheet→ As described in No. 21, closing the underside of the work container with a maximum inner diameter of 13m,
is being studied.
The material that can be used is being investigated and the required physical properties are being evaluated.
Inclusion of fibers of nylon, etc. for improving strength is being considered as well.
[3] Study on welding and cutting methods→ Along with above-mentioned [2], the methods of welding and cutting isolation sheets are also being studied.
[4] Evaluation using scale models, etc.
→ Based on the results of studies above mentioned in [1], [2], and [3], the feasibility is confirmed by means ofelemental tests using scale models, etc. (Proposed test items are indicated on the next page)[5] Study of isolation sheet remote handling equipment→ The isolation sheet needs to be handled remotely in actual use.
Based on the results of studies mentioned in [3], equipment for remote handling (welding remotely, etc.) is
studied.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project

No.39

1) Development of isolation technology to prevent the spread of contamination[Elemental tests using simulated test pieces]◆ Items to be verified through elemental tests (proposed)
No.

Items

Details

Remarks (Proposal on specific verification details)

1

Manufacturing
efficiency⚫ Manufacturing efficiency will be verified by test-manufacturing
isolation sheets.

・ Whether or not manufacturing the sheets in actual dimensions is possible (if it isdifficult to manufacture the large unitized large sheets, smaller sheets can bejoined together to get larger sheets), etc.

2

Collection
efficiency⚫ Method for easy collection when the isolation sheet isinstalled, will be studied, and verified through tests.

・ Whether the sheet can be folded to fit the assumed size
(folding method, whether the surface with the joint can be folded),etc.

3Air-tightness⚫ The method for converging (squeezing) the isolation sheet andensuring air-tightness by welding, etc. will be studied, and・ Leakage rate, etc.
verified through tests.

4

Cutting efficiency ⚫ The cutting efficiency of the isolation sheet will be verified.

・ Study of cutting method assuming remote operation, work
efficiency, etc.

(Remarks)・ The above items will be verified using scale models, etc. The verification items (target values and criteria, etc.) will be specified in the future.
・This plan may change depending on the progress in designing.

Converging
and welding[Illustration of manufacturing efficiency]
・ Study of dimensions considering welding(including excess length after squeezing)[Illustration of storage efficiency]
・ Study of folding method, required sizein the case of storage

Cutting[Illustration of air-tightness (converging and welding) and cutting]・ Study of converging and welding and cutting methods* Dimensions are being studied.
©International Research Institute for Nuclear Decommissioning7. Summary

No.401) Development of isolation technology to prevent the spread of contamination➢ Technology for confining (isolation mechanism) contaminated material during removal
and transportation of large structures is being studied. Isolation mechanisms including
opening/closing type, welding type, trap type and shatter-proof type were studied andcompared. Then, primary evaluation for the isolation mechanism was conducted, andthe welding type (isolation sheet) isolation mechanism was selected based on the
aspects of confinement capability and operability.

➢ The confining procedure using an isolation sheet is being studied. The method for
welding/cutting the isolation sheet, procedure for containing the structures into largetransfer containers, method for replacing the isolation sheet, etc. are being
crystallized.
➢ Test items and details for verifying the feasibility of the isolation sheet are being
studied.

©International Research Institute for Nuclear Decommissioning8. Specific Goals for Achieving the Purpose of the Project1) Development of isolation technology toprevent the spread of contamination

No.41

The contaminated material generated from work and the passageways in which it
spreads shall be examined, and the contaminated area classification required in thepassageways shall be clearly specified. Isolation mechanism (equipment and operating
methods, etc.) for preventing the spread of contamination shall be evaluated andselected from the perspective of confinement capability, possibility and operability of
remote operations, robustness and durability, inspection/maintainability, etc. and site
applicability shall be studied by means of elemental tests.
(Target Technology Readiness levels (TRLs) at completion of the project*: Level 3)

TRL level

Details

Phase

TRL7

Stage at which implementation is complete.

For practical use

TRL6

Stage at which on-site demonstration is conducted.

On-sitedemonstration

TRL5

Stage at which a prototype is manufactured based on the actual equipment and verified
in-factory simulated environment, etc.

TRL4

Stage at which functional tests are implemented at the test manufacturing level as adevelopment and engineering process.

Research forpractical use

TRL3

Stage at which development and engineering are carried out by using applied or
combined existing research. Or, stage at which development and engineering are
carried out based on fundamental data in fields in which there is no prior experience.

Applied research

TRL2

Stage at which development and engineering are carried out in fields in which there isalmost no applicable prior experience, and the required specifications are defined.

Applied research

TRL1

Stage at which specific details pertaining to the development and engineering targets
are clarified.

Basic research

Simulated verification*TRL： Technology Readiness Level©International Research Institute for Nuclear Decommissioning