Subsidy Project of Decommissioning and Contaminated Water Managementfor FY2021
Development of Fuel Debris Retrieval Method (Development of Isolation
Technology to Prevent the Spread of Contamination during Retrieval andTransportation of Large Structures)

Final Report for FY2022

June 2023
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． Specific Goals and Progress Assessment for Achieving the Purpose of
the Project©International Research Institute for Nuclear Decommissioning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)”No.2[Purpose for developing a 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).
The fuel debris present inside the RPV and PCV is assumed to be currently in a sub-critical state, however, the plant itself is in
an unstable condition unlike it initial designed state since the Reactor Building (R/B), RPV and PCV, etc. have been damaged dueto the accident. For this reason, the fuel debris should be retrieved and maintained under a stable condition to prevent the
spread of radioactive materials.
Against this background, this project aims to study the implementation of fuel debris removal on a further increased retrieval
scale in coordination with the engineering and project management activities undertaken by TEPCO in accordance with 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
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 level 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 are 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 to further
increase the retrieval scale in accordance with the Mid-and-Long-Term Road-map.
[Duration of the 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 studies in the ongoing subsidy projects were examined.
(1) Results of past subsidy projects related to the top access method[Results of studies conducted as part of Upgrading Fundamental Technology for Retrieval of Fuel Debris and Internal
Structures (hereinafter “Fundamental Technology Upgrade”: implemented in FY2017-18)]
•

•

Top
container

A rough plan for constructing the access route (removal of interfering objects) was
created and elemental tests were conducted using structural simulations of thereactor bottom to verify the feasibility of the removal procedure.
The time it takes to retrieve the components (throughput) was estimated by assuming
details of the procedure such as the unit of parts that will be cut, the shape andthickness of the parts to be cut, and the method used in cutting the parts.

Container craneFuel debris
retrieval cell

Fuel debris retrieval
cell craneEquipmentloading

CRD housing
clamp

DSP
Well

Dedicated cask

Canister
Inside thereactorRemoving large components fromthe reactor bottom

AWJ nozzle

The method for removing large components where structures inside the PCV are cut andstored in unit canisters to be transported outside of the reactor is quite challenging interms of workability and the time required for work.

RPV

ShieldedcontainerUC

PCV
Fuel debris

Implementation details pertaining to Development of Technology for Further Increasing
the Scale of Fuel Debris and Internal Structures (hereinafter, “Further Increasing the Scaleof Retrieval”: implemented in FY2019-20)]
Verifying the feasibility of the removal method where components are kept as large
possible and cut 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[Concept behind the new top access method (removing and transferring the unitized structure)]
The concept behind the method where the unitized structure is removed and transferred, which was studied under “Further Increasing the Scale ofRetrieval”, is described below.
✓ Individual components are transferred out as one unit.
✓ 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 using appropriate containers or the appropriate access route or a combinationof both.
✓ The work of finely cutting the components that are retrieved and packaging them into a container is carried out in a building that is separate from the R/B.

[Items studied under the “Development of Technology for Further Increasing theRetrieval Scale of Fuel Debris”]
The following items was studied in the FY2019-20 Subsidy Project(Development of Technology for Further Increasing the Retrieval
Scale of Fuel Debris).
✓ Study of a method for transferring (transfer route) the unitized
structure.
✓ Study of the method for disassembling the reactor bottom andrelated elemental tests.

[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.)

R/B
原子炉建屋
Crane
揚重機
Passageway
連絡通路

切断ツール
Cutting
tool
搬送装置
transportation
deviceRetrieval
device
取り出し装置

Additional
増設建屋 building

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

補助アーム
Auxiliary
arm

Lower
RPV下鏡
hemisphericaldome of RPV

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 container)(輸送専用容器)

Grating
insulating
グレーチング保温材
material
切断ツール
Cutting
tools(把持と切断機能あり)

CRD
housing
CRD.Hサポート
supportbeam and
ビーム、ブラケット
brackets(with holding andcutting functions)

HCU配管
HCU
piping

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

Method for transferring (transfer route) theunitized structure under consideration©International Research Institute for Nuclear Decommissioning

No.5

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

A method for reducing highcontamination areas in thepassageways is being studied.
[Scope of this project][1] Method for cutting large structures
Disassembling
解体装置
device

切断片取り
Crane
for handling
扱い揚重機
cut pieces

Disassembling
解体装置
deviceDisassembling
解体装置
deviceHoisting
切断片吊accessories
for
り具
the
cut pieces

走行

Guide
ガイド

Drive
motor (outside
駆動モータ(連絡通台形ネジscrew
Trapezoidal
thepassageway)
路外）

R/B
原子炉建屋

Shroudシュラウド
ヘッドボルト
head
bolt
RPV上蓋
RPV
upper lid

PCV
upper lid
ＰＣＶ上蓋

Cutting
切断マニピュレータ

manipulator

Cutting
切断マニピュレータ
manipulator

セパレータ
Separator

Passageway
連絡通路

スタットボルトStud
bolt

取り出し装置Retrieval
deviceA conceptual study was conducted in the “Development of Technology for
Further Increasing the Retrieval Scale of Fuel Debris” (implemented in FY2019- 20)

Method for cutting structures other than internal structures

Trapezoidal screw drive methodEndless roller method

Crane
揚重機

Cutting
切断マニピュレータ
manipulator

A conceptual study was conducted in the “Development of Technology for
Additional
増設建屋 building
Further Increasing the Retrieval Scale of Fuel Debris” (implemented in FY2019- 20)

搬送台車 cart
Transportation[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 lidDual
lid

Illustration of filling and cutting
Cutting[1]シュラウド把持部（穴加工し把持）

シュラウド

切断②

Filling andsolidification
断面全域の切断

ワイヤー

切断機[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 to ensuring safety during fuel debris retrieval work.

Cutting structures from the reactor bottom
Cutting
tool
切断ツール
搬送装置
transportation device

Collection
container
回収容器
transportation
搬送装置
device

補助アーム
Auxiliaryarm

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

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

Cutting tools
切断ツール
(with
holding and(把持と切断機能あり)
cutting functions)

Auxiliary
arm

Φ6m

HCU配管

*CRGT: control rod guide tube

Fuel debris at thereactor bottom

Lower
hemisphericaldome opening

HCU piping

Simulated collapsed
Geopolymer filling(Inner diameter of container: 300mm)
CRGT*.
Elemental tests were conducted in “Development of Technology for
Further Increasing the Retrieval Scale of Fuel Debris” (FY2019- 20)[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 were conducted in “Development of Technology for
Further Increasing the Retrieval Scale of Fuel Debris” (FY2019- 20)

Φ7m
A conceptual study was conducted in the “Development of Technology for
Further Increasing the Retrieval Scale of Fuel Debris” (implemented in FY2019- 20)©International Research Institute for Nuclear Decommissioning2. Results and Contents of the Study on Top Access Method Conducted as Partof Subsidy Projects

No.6[Relationship between items developed in past projects and this project]
CRD
housing
CRDハウジング
クランプ部
clamp

Project on Upgrading of Fundamental
Technology (implemented in FY2017-18)

AWJノズルAWJ
nozzleRemoval of large structures

炉底部の大型構造物の撤去
from the reactor bottom[Notes]Colors indicate the following contaminationlevelsR (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination)zone
G (Green): Green (low contamination) zone

Method for cutting pieces[Study of the method for cutting pieces inside PCV]➢
Implementation of elemental tests using simulated reactor bottom
structures➢
Estimation of throughput, identification of issues

Work
作業容器
container（遮蔽）(shielded)

G

Isolation
sheet
隔離シート
(air-tight)（気密）Dual lid

RY

二重蓋
可動フランジMovable flange

Project on the Development of Technology for Further
Increasing the Retrieval Scale of Fuel Debris(implemented in FY2019- 20)[Study of the method for transferring the unitized structures]➢
Implementation of elemental tests related to disassembling thereactor 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

Shielding
cart
遮蔽台車

Lower
下蓋 lid

大型切断工法Methodof cutting
large structures

R

Transport
cart
搬送台車

Large
transportation
大型搬送装置deviceLarge transfer
container
大型搬出容器R

Dedicatedtransport
輸送専用容器
container

Project of Technological Development for
Ensuring Safety(implemented in FY2020-21)

G

Method for transferring unitized large structures[Feasibility verification of the large transfer container lid]➢
Development and elemental tests of the air tight mechanism forthe container lid➢
Study of the method for criticality control after collection incontainers (during transfer)

This project[Development of Isolation Technology to Prevent
the Spread of Contamination]➢
Isolation technology development andelemental tests

Items to be studied in future➢

上蓋
Upper lid

Isolation
sheet
隔離シート

Study of technological challenges identified during engineering andtechnological development etc.

The contamination area classification in this slide is as of the start of this project.

©International Research Institute for Nuclear Decommissioning2. Results and Contents of the Study on Top Access Method Conducted as[Notes]Part of Subsidy Projects
Colors indicate the following contamination levels*[Development results up to FY2020 (studies)]
A conceptual study was conducted of the methods for reducing the highcontamination area in the passageways.

(Passageway method) Ver. 1
Setting up partitions using gates

Secondary boundary

Secondary boundary Retrieval device

Conceptual diagram

Retrieval device
Passageway

Additionalbuilding

Passageway

Transportation
cart

R

Dual lid
Dedicated transfer
container

Connecting
sleeveGate opening/closing device

Dual lid
Transportation
cart(Passageway method) Ver. 2
Setting up partitions using work containers
Secondary boundary

Additionalbuilding

Gate opening/closing device
Connecting
sleeveR (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.

Dedicated transfer
container

Y

PassagewayConnecting
sleeveRetrieval device
Work container

Transportation
cart
Work
container

Passageway

Additionalbuilding(Passageway method)

No.7

Work
containerGate
opening/closing
deviceConnecting
sleeveDual lid
Dedicatedtransfer
container

Transportation
cart

When transporting
work containers

G

Pros
Cons

・Simple retrieval procedures・Fewer number of equipment components,
less waste

・Less radioactive dust generated in cutting
will spread in the passageway because thegates are closed

・Less radioactive dust generated in cutting will
spread in the passageway because pieces are stored
in work containers
・In transporting the components, less radioactive
dust will spread in the passageway because the work
containers will be used in transport.

・While components are being cut, theradioactive dust from cutting will directly flow
into the passageway (more radioactive dust
will accumulate).

・When the gate is closed, the gate interfereswith the transport cart rail and the travel drive
unit.
・When the components are beingtransported, the radioactive dust that is
attached to the components will spread in thepassageway.

・The amount of secondary waste will increase withthe work containers.
Note: Because the work containers do not have a bottom lid,
the work container will be open when it is being transferred
onto the transport cart.

To prevent the spread of contamination due to radioactive dust flowing into the passageway, the Ver. 2, in which the structures can be processed and transported while partitioned off using
work containers, was studied as the primary method.
However, because the work containers do not have a bottom lid, the containers will be open when the containers are being transferred onto the transport cart, allowing contamination to
spread.
=> The fuel debris retrieval is likely to be a long project. The contaminated area should be minimized when considering the possibility of the need to perform maintenance on devices andrespond to emergencies. Therefore, it will continue to be studied as part of the FY2021 Development of Fuel Debris Retrieval Method Project.

The contamination area classification is as of FY2020 and will be reviewed in this project.

©International Research Institute for Nuclear Decommissioning2. Results and Contents of the Study on Top Access Method Conducted as
Part of Subsidy Projects

No.8[Development results up to FY2020 (studies)]◆ Work container conditions [(Passageway method) Ver. 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 that covers the entirety of the reactor well (large
inner diameter)
・Minimum sheet thickness considering the need to reduce
the radiation dose from inside the reactor (thin sheet)->Reduce the weight of the work container
Shielding theradiation from theinside of the reactor

Preventing spread ofcontamination during
cutting work

Work containers for transfer of structures
・Smallest size that can contain the structure
to be transferred (small inner diameter)

Work container
Shielding cart

・Sheet thickness considering reduction ofradiation dose from the structures to betransferred (thick sheet)->Reduce the weight of the work container

Approx. Φ13ｍ
When the work container isseparated, the reactor wellside and the underside of thework container are closed
simultaneously.

Approx. Φ8ｍ
Shielding the radiation
emitted from thetransported structures(Large amounts ofradiation emitted fromreactor internals

During cutting (disassembling) work (illustration)

Preventing the
spread ofcontamination fromadhered substances

When the work container
is being transferred (forboth cases)(illustration)

During transfer work (illustration)©International Research Institute for Nuclear Decommissioning

The work container dimensions in this slide are is as for FY2020 and will be reviewed in the construction method PJ (details in later slides).

3. Project overview

No.9

3.1 Links with other projects
Development of fuel debris
retrieval method
Sharing of the status of study➢➢

Continuous
monitoring

Development of side retrieval method
Development of top retrieval method

Sharing of the status of study

Sharing of technological challenges

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

Sharing of investigation needs/results

Internal investigation

Characterization
Development of analysis and estimation
technology for characterization of fuel debris
Coordination of containing,transfer and construction methods

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

Development of technology for
Investigation inside RPV

Sharing of technological challenges
・Sharing of safety scenarios
・Coordination of work steps

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

Development of liquid/gas phase systems,
criticality control technology
Sharing of analysis needs/results

Development of a system forcontinuous monitoring inside PCVDevelopment of technology fordetailed investigation inside PCVDevelopment of safety system

Technology for ensuring safety
Technology for ensuring safety

Containing, transfer andstorage technology
Development of technology for containing,transfer and storage of fuel debris
Coordination of containing, transfer
and construction 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 ofsubsidized projects and implementation policy
Development items involving
solicitation information ofsubsidized projects

Implementation policy

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

In order to enhance throughput for retrieving fuel debris and internal structuresusing the top access method, the method for transferring large unitized structures
has been studied since FY2019. The method being considered involves keeping
the reactor internals as whole and as large as possible, and pulling the structures
up to the Reactor Building (R/B) operation floor and transferring them to theadditional building using large transport equipment.
In order to contain radioactive materials and to reduce the radiation exposure of
the workers, the contamination of the passageway from the R/B operation floor to
the additional building should be minimized. A conceptual study is underway on amethod for preventing the spread of radioactive material within the passageways
where the contaminated structures are covered with a work container whencutting them within the reactor and when transferring them out to the additionalbuilding, and an isolation mechanism is used when transferring the work
containers from the reactor to the R/B operation floor.
In order to flesh out the measures to prevent the spread of contamination, thecontaminated materials generated in the work, the routes where these materials
may spread will be identified, and after clearly specifying the contaminated areaclass for the passageways, technological development of equipment and studiesof the operation methods for the isolation mechanism for preventing the spread ofcontamination 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 the project

No.11

Development of fuel debris retrieval method (FY2021 to
FY2022)

The following figure illustrates the retrieval method that employs isolation technology such as using work containers andisolation sheets with shielding function, in order to reduce the extent of contamination inside the passageways.
A configuration that will work well together with the large transfer containers and dual lid currently being developed will be
studied.
Isolation technology to prevent the spread of contamination (This project) → Development of isolation technology such as isolation sheet for
preventing the spread of contamination from the underside of the work container(Reduce the contamination level inside the passageways, reduce the radiation exposure of workers, enhance the operability of maintenance of cranes)Workcontainer(Shielding)G

Isolation
sheet(Air-tight)

R

Isolation
sheet

Shielding
遮蔽台車 cart

Method for
cutting large
structures

Y

R

Transportation
cart搬送台車

Confinement using an isolation sheet

Largetransportationequipment

R

Large transfer
containers

G

Reducing contamination inside the passageways using work containers
The contamination area classification in this slide is as of the start of this project.

[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 red border.
©International Research Institute for Nuclear Decommissioning3. Project overview
3.4 Points of concern for executing this project

No.12
Solicitation information details are as below.

The points of concerns for executing the project are described below.
[Points of concern]
In developing these technologies, the following points on the handling efficiency
and maintenance methods for remotely operated equipment will be considered.

・Equipment should be remotely maintained in general as they will be installed ina high radiation area.
・Contamination of the equipment and the decontamination necessary should betaken into consideration.
・The work area available for maintenance work is limited.
・Waste generated during maintenance work needs to be minimized.
・Installation and handling of criticality monitoring equipment needs to beconsidered.

©International Research Institute for Nuclear Decommissioning4. Implementation schedule

No.13: Planned[Schedule]: Planned (revised)*: Actual

FY2021

FY2022

Study items
4

5

6

7

8

9

10

11

12

1

2

3

4

5

6

7

8

Interim report▼

Major milestones

9

10

11

12

1

2

3

Final
report▼Interim report▼

Conceptual study (including study of the isolation sheet handling step)
Physical properties evaluation and study of the isolation sheet material

1. Conceptual study
Study of welding and cutting methods
Study of the remotely operated handling device

Element test plan

2. Planning ofelemental tests

Drum can test (squeezing, folding)

Test preparation/prototyping the device

3. Testpreparation/test
manufacturing of
testing apparatus

1/4 scale test

4. Element tests

Summary

5. Summary

Remarks

・General purpose polyethylene sheets were used in drum can testing (approx. 1/25th scale test).
・The feasibility of folding (squeezing), welding, and cutting of sheets with fiber were verified in the FY2022 element test (1/4 scale test).
・Remotely operated handling devices were studied in FY2022. (A device needs to be made and verifications need to be performed atscale.)*: Revised the plan to reflect progress made in studies and the results of element tests.

©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 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 of transferring the large unitized structure is being carried out
since FY2019. As part of this, the method of 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 of 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, ease 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 simulated
facility that use the studied technology.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of this project: 1) Development of isolation technology toprevent the spread of contamination

No.16[Issues]• Contamination could spread throughout the passageway.
• Contamination prevention measures need to be implemented considering on-site work efficiency offuel debris retrieval work.
[Implementation details]• The contaminants generated in fuel debris retrieval work and the routes by which these materials
spread will be clarified, and the contaminated area class for the passageways will be clearlyspecified.
• The isolation mechanism for preventing the spread of contamination will be evaluated and selectedfrom the perspective of confinement performance, certainty and workability of remote operations,robustness and durability, efficiency of inspection and maintenance, and the most appropriatetechnology will be studied.
• Methods to confine contaminated materials during the removal of large components andtransportation and their procedures will be developed.
• On-site applicability of the technologies studied will be evaluated by conducting elemental tests
using a simulated test body to verify manufacturing efficiency, ability to collect into the equipment,
air-tightness, and other items.
[Expected outcome]• Present a method to prevent contamination from spreading when transferring large contaminatedstructures.
• Present a contamination area class for the passageway based on the element test results.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination[Note](a) Approach to isolation technology[Clarification of the contaminated area classifications for the passageways]◆Approach to boundaries and contamination area classification➢ The primary boundary is comprised of the passageway, the secondary boundary is comprised of the R/B,
building cover, and additional building.
➢ Using the isolation sheet and work containers, the area will be managed to minimize the highcontamination area in the passageway as much as possible and to keep the passageway in the yellow(moderate contamination) zone as much as possible.

Passageway(Primary boundary)G

Isolation
sheet(Air-tight)

遮蔽台車 cart
Shielding

R/B, building cover(Secondary
boundary)

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 R, Y and G, and the
red zone is marked with a red border.

Work
container(Shielding)-150[Pa]*

R

R

No.17

Additional building(Secondary
boundary)

Y

Work container
decontamination
area

搬送台車
Transportation
cart

In this diagram, the work container is on
a level below the operation floor, but themost workable plan currently does not
lower the container from the operation
floor. (See next steps for details)

R
R

Large transfer
containers-64[Pa]*-400[Pa]*G

Contamination area classification
The contamination area classes are subject to change.

*Pressure values
are estimates©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination[Note]

Colors indicate the following contamination levels*
R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination) zone
G (Green): Green (low contamination) zone(a) Approach to isolation technology[Clarification of the contaminated area classifications for the passageways]◆Targets for passageway area conditions● During fuel debris retrieval work
[1] Reduce public exposure
・Reduce the dose rate at the site boundary
・Prevent radioactive dust from leaking into the environment[2] Reduce worker exposure
・Remotely operate/automate
Reduction of dose rate at
the site boundary(Passageway shielding+ work container shielding)

Passageway*Besides color, the main zones are marked R, Y and G, and the
red zone is marked with a red border.
The red zone is marked with a red border.

●During maintenance and inspection work
[1] Reduce public exposure
・Reduce the dose rate at the site boundary
・Prevent radioactive dust from leaking into the environment[2] Reduce worker exposure
Changes to be made with this project・Remotely operate/automate
・Improve the work environment: Workers could directly perform
maintenance if the spread of contamination inside thepassageways
could be prevented.
(on stationary equipment inside the passageways, such as large cranes)

Preventing radioactive dust from leaking into theenvironment(Passageway confinement+ work container confinement + passageway ventilation)

Building cover Large crane

Additional building

Work container

Transfer cart

Shielding cart

R
Work container遮蔽台車
side partition

搬送台車

Y

Reduction of dose rate
inside the passageways

Large crane

Reduction of dose
inside the passageway(shielding cartshielding)G

Preventing radioactive
dust leakage inside
the passageway(Reactor well-side
partition shielding +passageway
ventilation)

Y

Shielding cart

Reactor
遮蔽台車wellside partition

搬送台車

R
G

G

During fuel debris retrieval work

The contamination area classes are subject to change.

Additionalbuilding

G

R

Reactorbuilding

No.18

Reactorbuilding

During maintenance and inspection work
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.19(a) Approach to isolation technology[Development of the best isolation mechanism technology]◆Concept of confinement using the isolation mechanism (closing the underside of the work container)

When lifting thework container

Structure

Transfer to thetransfer cart

Leaks

Lift structures

Transfer to thetransport cart

Confinement
measures
Transfer cart

Because the underside of the work
container is not closed, it is
temporarily open when the it is beingtransferred to the transport cart

Prevention of
the spread ofcontamination*

Isolation mechanism(e.g., isolation sheet)

Transfer cart

Measures will be implemented toprevent contamination from spreadingfrom the structures inside the large
work container and the inside of thereactor.
©International Research Institute for Nuclear Decommissioning*: Though some leakage is acceptable as the passageway is part of the primary boundary, the spread of contamination should be minimized as much as possible.

6. Implementation Items of This Project: 1) Development of isolation technology to
No.20[Note]
prevent the spread of contamination
The colors indicate the contamination level.
(a) Approach to isolation technology[Development of the best isolation mechanism technology]◆Comparison of methods for closing the underside of the work container whenseparating the work container(1) Assumptions and required functions[1] The work container and the reactor well-side of the reactor will be isolatedwith the isolation mechanism.
・ Contaminants in the gas phase (particles) and the liquid phase (water
droplets) should be able to be confined (separated from the contaminatedenvironment).
・Should not interfere with the reactor well during handling.
[2] The weight of the work container is minimized.
・There are discussions being had on using containers of different sizes
depending on the work classification.
Can accommodate containers of different sizes.

R (Red): Red (high contamination) zone
Y (Yellow): Yellow (moderate contamination)zone
G (Green): Green (low contamination) zone
Work

作業容器
container（遮蔽）(Shielding)
Isolation

隔離シート
sheet
（気密）
(Air-tight)

Shielding
cart
遮蔽台車

Transfer
搬送台車
cart

Area where themechanism will
be used(2) Scope of application
・Target structures: structures within the reactor well (e.g., PCV head), reactor
internals
・Confinement area: seal on the reactor well-side, seal on the work container
bottom・Period: When placing the structures inside the work container(currently assuming that it will only be used temporarily)
Based on the above, an opening/closing type, a welding type, a trap type, theshatter-proof type of confinement methods for the underside of the container whenseparating the work container were compared.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project
No.211) Development of isolation technology to prevent the spread of contamination[Study of the most suitable technology related to the isolation mechanism]◆ Comparison of the method of closing the underside of the work container at the time of separating the work container(Results of primary comparison)
No

項目
Item

Shatter-proof
type
Welding
type
Trap type
接合方式
トラップ方式
飛散防止方式
Isolation
sheet
Surfacepainting
Air curtain
隔離シート
エアーカーテン
表面塗布• Air inlet and outlet ports are • The source of contamination• Air-tight lids are installed on the• Air-tight gates are provided on the • A middle portion of a cylindrical
・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 well ・容器側と原子炉ウェル側の両方に気
container side as well as the reactor ・容器側と原子炉ウエル側を連結した
sheet that connects the ・容器側と原子炉ウエル側の両方に空on the surface of theside, to which the container is 密性のゲートを設け、相互のゲートを
and 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
well side, and opening/closing iscontainer
side
and
the
reactorstructures is solidified andconnected, and opening and closing is
円筒状のシート類において、中央部を 気の吹出口と吸込口を相対させてエ
performedbysliding
thecontainer
that
the
ports
face
each
other
の蓋を接触・密着させた状態のまま一固めて剥離、飛散を防止
performed by rotating the container in its 接触・密着させた状態のままでスライ
well side is squeezed and アーカーテンを形成し切り離す。
peeled off using paint, etc. towhile both gates are in contact and 絞り込み接合・切断する。
to
form
an
air
curtainandtheentirety
while
both
lids
are
in
contact
and
体で旋回することで開閉する。
ドして開閉する。
welded/cut.
prevent scattering.
closely adhered to each other.
closely adhered to each other.
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
efficiency

3 ・液相(水滴したLiquid phase (drippingof water droplets)たり)Presence of
取り扱い時の4 interferences
干渉有無
while handling×• 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• According to the JPDR dismantling ・炉内構造物の内面、隙間を確実に塗• It is difficult to properly paint thefield test (results), concentration
・JPDR解体実地試験（実績）ではエ
inner surfaces and crevices of the
布することは困難
ratio in the air on both sides of thereactor internal structures.
アーカーテン内外の空気中濃度比約
air curtain was approx. 1/30*1.
1/30*1)〇
・容器側の蓋で受けは可能• Can be stored on the container side lid〇〇
××• Can be stored on the container •Can be stored on the container ・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 the・容器側ゲートで受けは可能
・容器側の下面シートで受けは可能
side gateside underside sheet
dropletssurface is a challenge×• Interferes with
・開動作時に、
the reactor
原子炉ウエルwell side whileと干渉
opening〇• Space is secured on the・連絡通路下面に空間確保
underside of the passageway

Interferencewith thereactor wellInterferes withthe container
for preventing
spread ofcontamination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 －• Sheets of different sizes can ・容器側の寸法に合わせて吹出口／
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of different• Everything including the lid on 要あり。
(Opening / closing is not•
Everything
includingthegate
provided in accordance with (開閉不要)
belayered(example
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
吸込口を配置on the reactor well side needs 紙に一例）
the reactor well side needs torequired)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××

The isolation sheet was selected considering the confinement performance for the underside of the work container (separation from the contaminated environment, applicability to containersof differing sizes).
The use of other technologies and use in combination with water scattering sprays will be considered if work containers are not going to be used or depending on the environmental
conditions (e.g., dust concentration).

©International
Research Institute for Nuclear Decommissioning
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”*2) Though the confinement of the underside of the work container was evaluated as ×, it could be applied to scattering prevention when removing the shield plug.

6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination(a) Approach to isolation technology

No.22[Study of the procedures for the confinement of contaminated materials during the retrieval and transportationof large structures]◆Study of procedures for confinement using isolation sheetsWorkcontainer

Collection box(Isolation sheet case)To the additionalbuilding

Shielding cart

Shielding cart

Isolation
sheet baseTransfer cart
Welding/cutting
Isolation
sheet

Isolation sheet

Step 1: Lift up (raise) the work container

Step 2: Weld and cut the isolation sheet

Transfer cart
Step 3: Evacuate the work container to theadditional building

Carrying out the work container using the isolation sheet[Overview]⚫ The edges of the isolation sheet are hooked onto the isolation
sheet base when the work container is put in place. The sheet isdeployed when the work container is lifted.
⚫ Welding and cutting of the isolation sheet is performed using thesides of the shielding cart and transport cart.
⚫ The work container, sealed by the isolation sheet, is transferredto the additional building using the transport cart.

Isolation sheet

Lift

Isolation sheet

Isolation sheet

Join (weld)

Cut

Welding and cutting©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.23(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Work container overview (taken from the results of the study on the construction method PJ)✓✓

The diameter and height of the work containers should be kept the same when possible. The inside of the container needs to be different
between the containers used for fabrication and those used for transfer, and each should be dedicated to the task. Because the core and thereactor bottom are heavier than the reactor internals, a larger crane will be installed.
=> Three types of work containers will be prepared.
The location at which the work container will be placed should change depending on the item to be removed.

List of the work container placement and type of work containers used for the item to be transferred out
Items to be carried out

PCV head, RPV head insulation, RPV
head

Height at which the work
container is placed

On the operation floor (cell floor)

Work container (during
cutting)

Dryer, separator,
FDW/CS*

Core/reactor bottom
RPV flange surface level

Work container [1]Work container (duringtransfer)

Work container [2] (for transferring
heavy weight objects)

Work container [1]’Work container

Work container

Work container

Area to be
removedArea to be
removedArea to be
removedInstalled work container©International Research Institute for Nuclear Decommissioning*FDW/CS: Feed Water System/Core Spray System

6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.24(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Work container overview (taken from the results of the study on the construction method PJ)✓ The configuration of the three types of work containers used in the method for transferring the unitized structure is as follows.
*Excluding the crane room

Work container [1][Overview andCable
configurationof eachcarrier
work container]
Illustration

Crane

Work container [1]’Work container [2]
Crane

Crane
Hoisting
accessories

Hoisting
accessories

Dismantlingequipment
Use

Cutting the structures and fuel debris

Transferring the structures and fueldebrisTransferring the core and the reactor
bottomInternal
equipment

Crane, cable carrier, dismantlingequipment

Crane (150 tons), hoisting attachments

Crane (400 tons), hoisting attachments

Dimensions[mm]

Φ8900×H9500

Φ8900×H13270

Φ12600×H11840(Φ6000×H7770: excluding the craneroom)

Mass [ton](only thecontainer)

Approx. 680

Approx. 680

Approx. 410

Shieldingthickness [mm]

250

250*

250*
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.25(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Shield plug removal
The shield plug removal steps developed in the construction method PJ are shown below. Because of the location and size of the shield plug,
it was determined that is not reasonable to transfer the shield plug using a work container. The plan is to use a dedicated transfer device (shieldplug transfer device) and container.
Removal work will be performed while also implementing dust scattering prevention measures (e.g., spraying water), together with negative
pressure management to prevent the spread of contamination.

Shield plugtransfer device

Cranemechanism

Transfer cart

Shield plug
Shield plug

Transfer
container

1. Transfer the shield plug transfer device

2. Lift up the shield plug

Transfer
container lid
Transfer cart

Transfercart
3. Transport the transfer cart to below the shield plug, collect in container

Shieldingcart
To the additionalbuilding
4. Close the transfer container lid, move out the transfer cart
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.26(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of installation sheet base installation work
After removing the shield plug, a base to attach the isolation sheet will be transferred in and installed at the reactor well opening.
Isolation sheet base

Passageway

A

B

A

B

Isolation
sheet baseA-A arrow view Isolation sheetbase water seal

Isolation sheet baseTransfer cart rail
R/B

Isolation sheetbase water seal

Passageway
Water seal

Isolation sheet base

Perimeter cover Isolation sheet base water seal
B-B cross section

The outer perimeter ofthe isolation sheet basewill sealed by the water
seal.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.27(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Isolation sheet installation
The isolation sheet will be placed in the isolation sheet base as shown below. The isolation sheet will be hooked onto the water seal
part of the isolation sheet base.

Isolation sheet

Isolation sheet base

Passageway

A

Isolation sheet base

A

B

B

Isolation sheet

A-A arrow view Isolation sheetbase water seal

R/B

Isolation sheetbase water seal

Isolation sheet (*)

Isolation sheet baseIsolation sheet seat area

B-B arrow view

Isolation sheet base
Water seal(*) Installation illustration.
In reality, it will be pulled toward the inside of the reactor due to negative pressure.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.28(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of the RPV head removal work
Below is an illustration of the RPV head transferred out using the work container being developed by the construction method PJ tosecure shielding and air-tightness.
1. Transfer the work container for cutting work

Install the work
container for
cutting work

2. RPV head bolt cutting

Install the isolation
sheet inside thewater seal dike
Polar craneTransfer cart

3. Evacuate the work container for cutting work, transfer the work
container for structure transfer*

Place the work container for structuretransfer(Transfer after the work container for
structure transfer is evacuated*)

Set in place theisolation sheet in
the water seal dike

4. Transfer the RPV head
RPV head

Work containers fortransfer of structures

Isolation
sheet
Evacuate the polar cranedismantling equipment and work
container for cutting work

©International
Research
Institutefor Nuclear
Decommissioning*: The illustration describes the work container for cutting work and the work container for structure transfer in the same diagram,but in reality,
the work
container
for structuretransfer
will be transferred in after the work container for cutting work is evacuated to the additional building side.

6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination(a) Approach to isolation technology

No.29[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (1/9) [Precondition: RPV head bolt is cut, the work container for cutting work has been evacuated]
Gate
Work
container [1]’Existing isolation sheet
Existing isolation sheet

Shielding
cart
Transfer
cart
Existing
isolation sheet

Isolation sheet base water seal

Step 1. Transfer in the work container for
structure transfer

Isolation sheet in Step 1*
New isolation sheet
Work container

New isolation
sheet

Work
container [1]’Shieldingcart

New isolation sheet

Contaminated area

Transfer
cart
Existing
isolation sheet

Hooked onto row A(Inner periphery)
Existing isolation sheet

Hooked onto
row B

Hookedonto row A

Existing isolation sheet

Step 2. Transfer the work container and the shielding cart

Isolation sheet in Step 2*©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed.

6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.30(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (2/9)
New isolation sheet
Work containerWork
container [1]’New isolation
sheet

New isolation sheet

Shieldingcart

Hookedonto row B

Contaminated area
Transfer cart
Existing
isolation sheet

Hooked onto row A(Inner periphery)
Existing isolation sheet

Existing
isolation sheet

A arrow view

Hookedonto row A

Step 3. Evacuate transfer cart
Isolation sheet in Step 3*

Existing
isolation sheet

Isolation sheet seat area

Water seal

Isolation sheet
base©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed.

6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.31(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (3/9)

New isolation
sheet

Work container [1]’Existing
isolation sheet

Hooked onto row B(Outer periphery)Contaminated area

Install a seat on the water seal wall (outer
periphery) for hooking on the sheet-> Consider having a remotely operated device
such as a flexible structure arm access thewater seal from the outer periphery and hook
the sheet onto the row B seat (outer periphery)

Step 4. Lower the work container, install a new isolation sheet

New isolation
sheet

Hooked onto
row A
Hooked onto
row B

Isolation sheet in Step 4*

Moving arm

Existing
isolation sheet

Isolation sheet seat area
Water
seal

Work arm
Isolation sheet
base

Flexible structure arm©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed.

6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.32(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval andtransportation of large structures]◆RPV head removal work steps (4/9)

The procedures for cutting andcollecting the existing isolation sheet
are described in the next slide

New isolation sheet
Cut

Work container [1]’Cut

Hookedonto row A

Removal device
Contaminated area

Hooked onto
row B

Step 5. Cut the existing isolation sheet, lower theremoval device

Isolation sheet in Step 5*©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed.

6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination(a) Approach to isolation technology

No.33[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (5/9)[1] Cut the existing isolation
sheet(Because the isolation sheet islarge, it is cut so that the arm cangrab and lift it)

Work container [1]’Elevating arm (2 units)

Circling arm (2 units)
includes a seat cutter
Movable range 270° (*)

Removal device(*)The remaining 90° of the movable range exists to ensure the sheet is not cut off.

Step 5. Cut the existing isolation sheet, lower theremoval device
Existing isolation sheet cutting and collection procedures: Overview(See next slide for detailed procedures)① One circling arm will grab the existing isolation sheet, and the sheet
cutter on the other circling arm will cut the existing isolation sheet
along the circumference. (Because the isolation sheet is large, it is cut
so that the arm can grab and lift it)② The elevating arm will grab the cut existing isolation sheet and hook it
onto the work collection hook on the top part of the work container.
③ The isolation sheet seats will be released from the hooks④ The work container will be raised a little to pull in the sheet on the seatside into work container using the circulating arm and elevating arm,
which will then be fixed onto the collection hook similar to [2] above.

Adjusted so that the sheet collected with the collection
hook does not stick out from the bottom of the work
container[2] Lift and fix the cut sheet[3] Releasefrom the seat[4] Raise the work container a little
bit, pull in and collect the sheet

Cutting and collecting the existing isolation sheet©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.34(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (5/9): [Supplement] Existing isolation sheet cutting and collection procedures

Elevating arm A
Circulating arm A

Circulating arm A
Cut part

Circulating arm B

Circulating arm A

Circulating arm B

Cut part

Cut edge
Cut area
Isolation sheet①② Grab the cut edge with the circulating arm A and cut
the 180° range with the circulating arm B

Grab the sheet with the circulating arm B andcut the 90° range with the circulating arm A

Collection hook

③ Move the circulating arm A near the elevating arm andhand over the sheet to the elevating arm

Elevating arm A

Elevating arm A

Circulating arm A
Cut part
Elevating arm B

Circulating arm B gripper
Cut sheet edge

④ Raise the elevating arm A⑤ Grab the other cut edge of the sheet with the elevating arm B⑥ Hook the sheet held by the elevating arm A onto thecollection hook

⑦ Hold the remaining part of the cut sheet with the circulatingarms A and B(prevent it from falling when the work container is raised)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.35(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (5/9): [Supplement] Existing isolation sheet cutting and collection proceduresCollection hook

Seat-side sheet
Cut-side sheet
Circulating arm A

Seat

Elevatingarm B

Elevating arm A

Circulating arm A

Circulating arm B gripper
Circulating arm B gripper⑧⑨⑩

Elevating arm A

Circulating arm A

Elevating
arm B

Seat
Water seal
Release the isolation sheet seat
Raise the work container
Pull on the seat-side sheet with the circulating arms andelevating arms and pull in the sheet seat from the water
seal into the work container⑪⑫

Bring the circulating arms A and B near theelevating arms A and B
Raise the elevating arms and hook the gripper
onto the collection hook⑬⑭

Transfer the cut parts held by the circulating arm A onto
the elevating arm A
Transfer the cut parts held by the circulating arm B onto
the elevating arm B

Elevating arm A

Elevating arm B
Circulating arm A⑯⑮

If the sheet doesn’t fit into the work container, repeat the following until it is fully contained in the work container.
a. Pull up the bottom of the sheet with the circulating arm
b. Hand it over to the elevating armc. Hook on to the collection hook

Raise the elevating arm to pull up the sheet©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.36(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (6/9)
Existing isolation sheet(cut around thecircumference andstored)Work container [1]’New isolation sheet

RPV head

Hooked onto row B

Contaminated area

Step 6. Remove the RPV head

Isolation sheet in Step 6*
New isolation sheet

Work container [1]’New isolation
sheet

Hooked onto row B

Step 7. Lift up the work container

Isolation sheet in Step 7*©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed.

6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.37(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (7/9)
New isolation sheet

Work container [1]’New isolation sheet
Shielding cart

Welding and cutting
device(moves to the right sideof the diagram)Transfer cart

Fold, weld, andcut the newisolation sheet

Hooked onto row B

Step 8. Fold, weld, and cut the new isolation sheet

Isolation sheet in Step 8*

RollerSheet fixing jig
Roller: for folding and fixing the sheet

Sheet cutter
Welding
Weld repair device
machine

A

Sheet

High
adjustingmechanism

Welding machine(welding horn)

Welding
receiver

Welding
machineShielding cart

Clamping jig
Welding the isolation sheet

A-A arrow view
Transfer cart

A

Folding, welding, and cutting the isolation sheet(load the welding machine onto the cart,
fold and fix the sheet with the rollers on the top and bottom of the cart, have thewelding machine slide in toward the center to weld)

Sheet fixing jig(for welding)©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed.

6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.38(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (8/9)

New isolation
sheet◼ Considering having the flexible
structure arm and other remotely
operated devices access the sheet
from the periphery to change the hookon which it is hooked to the row A seat(inner periphery) hook (one idea)

Step 8. Fold, weld, and cut the new isolation sheet(state after cutting)

Hooked onto row A

Isolation sheet in Step 8 (after cutting)*

Moving arm

Work arm

Flexible structure arm©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed6. Implementation Items of This Project: 1) Development of isolation technology
to prevent the spread of contamination

No.39(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆RPV head removal work steps (9/9)
New isolation sheet
New isolation sheet

Work container [1]’Shielding cart

Hook on to row A(inner periphery)
Closing lid

Transfer cart

Contaminated area

Hook on to row A

Isolation sheet for Step 9 and 10*
Step 9. Move the transfer car, lift up the work container

Work container [1]’Shielding
cart

Transfer cart

Transport the work container into theadditional building, and once the structures
are removed, replace with a new isolation
sheet within the additional building

Closing lid

Step 10. Transport the work container, move the shielding cart
©International Research Institute for Nuclear Decommissioning*: In this diagram, the isolation sheet in the diagram on the left has been enlarged and the carts that do not affect the isolation sheet have been removed6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.40(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (1/8): attach the new isolation sheet for transfer
onto the work container

Gate (closed)
Isolation sheet replacement cart
Work container

Isolation sheet
Replacement cart
New isolation
sheet for transfer(collection box)

Isolation sheet baseExiting isolation
sheet for transfer

Structure

Transfer cart

Attaching the isolation sheet for transfer

New isolation sheet for transfer(collection box)

Work arm(A work arm will be installed in the in the
additional building in advance to assist
with removing the isolation sheet)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.41(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (2/8): Place the work container in the seat, release
the sheet

Crane

Work procedures① Place the work container in the isolation sheet base
② Place the seat of the isolation sheet for transfer in the outer
periphery of the water seal
③ Cut the isolation sheet attached to the bottom of thecontainer (that was used to remove the structure)④ Grab the isolation sheet attached the bottom of the container
and the existing isolation sheet for transfer with the workarms.
⑤ Lift up the work container a little bit.

Isolation sheet replacement cart

Work container

Isolation sheet attached to the bottom of
the container
Existing isolation sheet for transfer
New isolation sheet for transfer(collection box)

Structure[3] Cut the isolation
sheet attached to thebottom of thecontainer[5] Raise the work
container a little bit[2] Hook the seat of
the isolation sheet
for transfer onto thehooks on the outer
perimeter of thewater seal

[1] Place the work containeron the isolation sheet baseIsolation sheet baseTransfer cart

Work arm[4] Grab the isolation sheet attached tothe bottom of the container and theexisting isolation sheet for transfer
with the work arms

Water seal
Seat of the isolation sheet for transfer

Large transfer containers©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.42(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (3/8): Remove the existing isolation sheet (collectin the large transfer container)

Crane

Work procedures① Release the seat (inner peripheral side) of the existing
isolation sheet for transfer.
② Use the work arm bands to lift the isolation sheet
attached to the work container bottom and the existing
isolation sheet for transfer held by the work arms down
into the large transfer container.
③ Place the work container in its place (put down thecontainer in its place)

Isolation sheet attached to the bottom of the container
Existing isolation sheet for transfer

Isolation sheet replacement cart

Work container

Structure

Isolation sheet baseTransfer cart

Work arm[1] Release the seat of
the existing isolation
sheet for transfer[3] Land the work
container[2] Use the work arm bands to lift the isolation
sheet attached to the work container bottom
and the existing isolation sheet for transfer
held by the work arms down into the largetransfer container.

Seat of the existing isolation sheet
for transfer (inner peripheral side)

Removed isolation sheet that was attachedto the bottom of the container and theexisting isolation sheet for transfer

Large transfer containers©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.43(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (4/8): Remove the structures inside the work
container

Crane

Work procedures① Lift down the structures inside the work container andstore them within the large transfer container.
② Receive the isolation sheet used to remove thestructures contained inside the work container with thework arms, and store in the large transfer container.

Isolation sheet replacement cart

Work container

Structure

Isolation sheet baseTransfer cart

Work arm

Large transfer containers©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.44(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (5/8): Weld and cut the isolation sheet fortransfer

Crane

Gate (closed)
Isolation sheet replacement cart

Work container
New isolation sheet for transfer

Transfer cart

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(a) Approach to isolation technology

No.45

To be performed each time after the work container is used

[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (6/8): Decontaminate the inside of the work
container
Crane

Gate (closed)

Decontaminationequipment

Work container

・Because the decontamination area
is a high contamination area, it will be
partitioned off from other areas
・Decontamination equipment will beplaced in the decontamination area inadvance to decontaminate work
containers

Drainage system©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination(a) Approach to isolation technology

No.46

To be performed each time after the work container is used

[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (7/8): Lift up the work container

Crane
Gate (closed)

Work container

Isolation sheet for lowering
down the work container(See Isolation sheet B, No.49
and 50)・The collection box will be removed in
the decontamination area and will be
individually decontaminated, then reused
・The remaining isolation sheets in thecollection box will be removed in thedecontamination area and disposed of
via a different route than the largetransfer container transfer route

Because the decontamination
area is a high contaminationarea, it will be partitioned offfrom other areas

Drainage system©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination(a) Approach to isolation technology

No.47

To be performed each time after the work container is used

[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Overview of procedures for handling the isolation sheet in the additional building (8/8): Attach a new isolation sheet to the work
container

Gate (closed)
Isolation sheet replacement cart

Work container
New isolation sheet(for removing structures)
After the new sheet is attached, thework container will be returned to the
R/B side and to remove other structures©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.48(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval and transportation of large structures]◆Isolation sheet when installing the work container on the RPV flange surface: Installing the isolation sheet baseBelow is an illustration of the isolation sheet base when the work container is installed on the RPV flange surface.
The isolation sheet base for removing reactor internals will be installed on top of the isolation sheet base for removing structures.

Hoisting
accessories

Water seal
Shielding cart

Work container
Transfer cart

Isolation sheet base forremoving reactor internals(to be newly installed because
the work container will be
installed on the RPV flange
surface)

Isolation sheet base for removing
structures inside the reactor well(isolation sheet base used whenplacing the work container on theoperation floor and removing thestructures in the reactor well)

Isolation sheet base for removing reactor internals©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination
Isolation sheet A:(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval andtransportation of large structures]◆Isolation sheet when installing the work container on the RPV flange surface: work steps (1/2)
An overview of the work steps is shown below. The contaminated areas are marked in red.
1. Carry in the work container

2. Set the starting position for the work container
Set the isolation sheet A in the water seal dikeWork container
Collection box B(case for isolation
sheet B)
Collection box A(case for isolation
sheet A)

Isolation sheetbase forremoving
reactorinternals*

Isolation sheet B

Lift down

No.49

Isolation sheet for evacuating the work container(to be folded, welded, and cut using the sameprocedures as when installing it on the operation
floor as described in previous slides)
Isolation sheet B:
Isolation sheet for lowering down the work
container(to prevent contamination from spreading fromthe sides of the work container)

3. Install the work container on the RPV
flange level
Lift up the structures into the work
container

Isolation sheet B
Lift down

Isolation sheet A
Isolation sheet A

Water seal

Water seal

Isolation
sheet B
Structure©International Research Institute for Nuclear Decommissioning*This base will be installed on top of the isolation sheet base for removing the structures in the reactor well (omitted in the diagram above).

6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination
Isolation sheet A:(a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval andtransportation of large structures]◆Isolation sheet when installing the work container on the RPV flange surface: work steps(2/2)
An overview of the work steps is shown below. Note, the contaminated areas are marked inred.
4. Lift up the work container

Isolation sheet for evacuating the work container(to be folded, welded, and cut using the sameprocedures as when installing it on the operation
floor as described in previous slides)
Isolation sheet B:
Isolation sheet for lowering down the work
container(to prevent contamination from spreading from thesides of the work container)

6. Transfer the work container

5. Weld and cut isolation sheet A

Work container

Isolation
sheet B

Isolation sheet B

Structure

Structure

Work container

Work container

Isolation sheet B

No.50

Structure

Isolation sheet A

Welding/cutting

Isolation sheet A

Isolation sheet A©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination[Note](a) Approach to isolation technology[Study of the procedures for the confinement of contaminated materials during the retrieval andtransportation of large structures]◆Study of the handling of the isolation sheet after structures have been removed (used isolation sheet)

No.51

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 R, Y and G, and the red zone
is marked with a red border.
The red zone is marked with a red border.

The plan is to use the isolation sheet primarily in [1] removing the structures and [2] transferring the structures as shown, in the diagram below. The way in which theused sheets will be dealt with is described below.
[1] When removing the structures: The cut isolation sheet is stored in the work container together with the structures with the removal device and transferred to theadditional building-> A new isolation sheet for transfer will be attached to the outer perimeter of the work container on the additional building side. Then, work will proceed to Step [2][2] Transferring the structures: The cut isolation sheet in [1] above, the new isolation sheet for transfer attached in [1], and the structures will be transferred to thelarge transfer container-> Close the large transfer container using a dual lid mechanism and transfer out of the additional building.
Once the large transfer container is transferred to a different building, the isolation sheet will be taken out when the structures are taken out from the large transfer
container for storage, and processed as waste.

G[1] When removing
structuresWork
container

Y
Place a new isolation
sheet in the work
container outer periphery

R[2] When transferring structures
Shielding
遮蔽台車cart

R

搬送台車cart
Transfer

In this diagram, the work container is on alevel below the operation floor, but themost workable plan currently does not
lower the container from the operation
floor similarly to previous steps.

R

Dual lid (release)

Large transfer
containersG
The contamination area classes are subject to change©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.52(b) Testing plan
[Isolation sheet requirement specification]
Required specifications for the isolation sheet that will be used in negative pressure and in a high dose environment are as follows.
ID.

Item

Specifications

Remarks1

Tensile strength

High strength considering the following actual unit conditions.
・Negative pressure: -400 [Pa], sheet dimensions: approx. φ13[m]2Tear strength
Puncture strength

To be high strength.
(Choose from among materials chosen for its high tensile strength andradiation resistance that are also strong against tears and puncture.)

3

Radiation resistance

Should be 100[kGy] or above considering the following.
[1] When removing structures
・Maximum dose (estimate): 1000[Gy/h]・Period (estimate): Around 3 days at most=> approx. 72 [Gy][2] When closed
・Atmosphere inside the reactor well (estimate): 4[Gy/h]・Period (estimate): 1 year=> approx. 36 [kGy]4Bondability (sealability)

Can be bonded remotely and can maintain negative pressure.

5

Cutting performance

Can be cut remotely.

[1] Once the structures are collectedin the work container, the work
container will be loaded onto thetransport cart. The transport cart willthen seal the bottom of the work
container. Therefore, it is estimatedthat the isolation sheet will seal thebottom of the work container whenremoving the structures for around 3
days.
[2] The closing lid will be used inclosing the container.
To be of a material that can be easily
welded and cut.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.53(b) Testing plan[Comparative assessment of isolation sheet materials]
・Based on the required specifications, thermoplastic resin was chosen as a candidate considering its bondability and cutting
performance.
(Thermoplastic resin can be easily bonded with welding.)
・Polyurethane resin, which is a high tensile strength and radiation resistant thermoplastic resin, is being considered.
The tensile strength and puncture strength of polyurethane resin manufactured by different manufacturers were compared.
ID.

Item

Candidate A

Candidate B

Candidate C

Candidate D

Tensile strength [MPa]

71.5

63.5

83.3

67.8

Tensile fracture elasticity [%]

677

663

468

504

Measured as areference

Tearing strength [kN/mm]

13

137

69

87

Measured using the
Trouser Tear Method

Puncture strength [N]

11.9

19.5

24.6

30.6

・Ether series
・Thickness: 0.25[mm]・Commercially sold・Ether series
・Thickness: 0.2[mm]・Prototype of the
manufacturer

12Remarks・Ether series
・Thickness: 0.2[mm]・Commercially sold・Ester series
・Thickness: 0.2[mm]・Commercially soldRemarks

・All of the candidates have high tensile strength and tensile fracture elasticity.
・Candidate B has the most tear strength, candidate D has the most puncture strength.
-> The strength and radiation resistance of candidate B with fibers added was measured in preparation for the
possibility that higher strength is needed for the actual full-scale devices and equipment.
Because the ease of handling of all candidate materials are about the same, tests were performed with candidates B(with and without fibers added) and candidate D.

Sheet with fibers©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.54(b) Testing plan[Comparative assessment of isolation sheet materials]
・Changes in tensile strength and tear strength of materials with fibers after gamma radiation

ID.

1

2

3

Item

Mesh
configuration
Tensile strength
after gamma
radiation[MPa]
Tear strength after
gamma radiation[kN/mm]*PET: polyethylene terephthalate

Candidate B (nofibers added)

Candidate B/ PET
fibers*Candidate B/ aramid
fibers*Fineness of the fiberused [dtex]
Density [# ofstrands/inch]

―

1110

3160

―

2.54

3.5

0[kGy]

41.5

35.4

310.4

100[kGy]

27.2

37.7

311.8

500[kGy]

20.0

28.9

321.7

0[kGy]

109.7>295.4>667.6100[kGy]

161.4>247.3>540.0500[kGy]

129.7>232.4>357.3・By adding fibers, the reduction in tensile strength even when it isirradiated by 100[kGy] can be minimized (strength will be increased)
and tear strength can be increased.

・In measuring the tear strength, the materials with PET fibers andaramid fibers tore when the weft came out, and the figures are likely ameasure of the bonding at the fiber-resin interface.

Candidate
B/PET fibers

0kGy

Weft came out

100kGy500kGyCandidate B/
aramid fibers*

0kGy

Weft came out

100kGyGy

500kGyMeasuring the tear strength of the sheet with fibers©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.55(b) Testing plan[Study of the welding method]
Because the polyurethane is a thermoplastic resin, it can be welded. Ultrasonic wave welding, which can weld together multiple
sheets at once, was studied as a welding method.
High-frequency welding is also a candidate though there are issues such as the need for high (around 4000 V), need for extra
safety, and the need to downsize the device.
[Equipment configuration*]
Press

Exothermic
reactionPower

Ultrasonic wave welding*(around 200V)

Oscillator

Place the item to be welded

Isolation sheet

Horn
Horn

CradleHorn

The horn can be inserted to weld

Press, horn
Examples of horn shapes

Ultrasonic wave welding of theisolation sheet

・By adding ultrasonic wave vibrations with the vibrator and pressure to the thermoplastic resin at the same time, the resin can beinstantaneously melted and welded.
・The horn can be manufactured to suit the usage and item to be welded.
・The above diagram describes a setup where the item to be welded is placed between the horn and the cradle, then welded. The item canalso be inserted between the horns and welded.
*Source: Seidensha Electronics Co., Ltd. website (https://www.sedeco.co.jp/)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.56(b) Testing plan[Study of cutting methods]
The ultrasonic wave cutter, which also uses the ultrasonic wave similar to welding and has the following benefits,
was studied as a cutting method.
・The cut cross section is clean.
・Is faster at cutting than other cutters and generates less shavings.
・Because the ultrasonic wave unit is small, it can easily be mounted onto machines such as a multi-jointed robot.

[Equipment configuration*]
Though the basic configuration is the same as the ultrasonic wave welder in the previous slide, the horn will bedifferent.

Power

Enlarged horn
Oscillator

Horn*Source: Seidensha Electronics Co., Ltd. website (https://www.sedeco.co.jp/)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.57(b) Testing plan
[Basic test]
A basic test at a drum can scale (approx. 1/25th scale) was conducted to study the isolation sheet squeezing (folding) method.
[Study (verification) items]

ID.

Item

1

Sheet shape

2

Squeezing
methodCylindrical sheet
Collect (push in) the sheet to the center using a twopronged fork to squeeze
Squeeze

3

Plan B: Fold so that the sheets do not
overlap

Plan A: Simply squeeze toward the center

Fold the sheet as many time as possible while making
sure it does not overlap and squeeze
Two-pronged, T-shaped fork

Sheet

Sheet

Drum canSheet

Squeeze

Illustration
Two-pronged fork

Squeezing jig

4

Advantages

・Can be easily squeezed toward the center・Because the sheet will be pushed into a small area
near the center, the number of times it has to be welded
could be reduced

5

Disadvantages

・Welding will be difficult as there will be variation in
sheet thickness after it is squeezed and will be many
wrinkles and gaps in the sheet

・There will be less variation in sheet thickness,
improving weld quality

・Folding is difficult (requires ingenuity)・Because a large area will need to be welded, thenumber of times it needs to be welded will increase©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.58(b) Testing plan
[Basic test: Equipment configuration]⚫ A collection box that will collect the isolation sheet was placed near the top of the drum can, and awater seal dike for fixing the isolation sheet near the bottom.

Collection box(can be removed)

Tube to keep it airtightPressureadjusting tube

Upper drum can

Raise

SpongeTension control

Atmosphericpressure

Negativepressure

Isolation
sheet

Hook for fixing theisolation sheet

Water seal dike(cannot be
removed)

Water

Lower drum can©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(b) Testing plan

No.59

[Basic test: Equipment configuration]

Lower drum canCollection box

Water seal dike

Partially enlarged

Enlarged picture

Isolation sheet
Tension adjusting tube
Hook

EyeletSpongePhoto of the upper part of the drum
can/collection box

Photo of the bottom part of the drum can/collection box(The photo of the whole drum above was taken before the isolation sheet was attached.)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination(b) Testing plan

No.60

[Basic test: Equipment configuration (collection box preparation)]
Fold the isolation sheet

Raise the tension adjusting tube pressure

Attach the isolation sheet to the collection box

Attach the collection box to the upper drum can©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination(b) Testing plan

No.61

[Basic test: Equipment operation checks]⚫ It was verified that the isolation sheet would come out from the collection box as planned when
the upper drum can is raised.
⚫ It was verified that airtightness could be secured with a maximum 450[Pa] differential pressure.
(verified the effectiveness of the water seal dike/tube for securing airtightness)

After 10 minutes the clearance for the upper and lower drumcans was 400 [mm] and the differential pressure 450 [Pa]Wrinkles were observed
along where the eyelets are

Testing(differential pressure 450 [Pa], clearance on the top and bottom 400 [mm])©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.62(b) Testing plan
[Basic test: Overview]⚫ Performed a isolation sheet squeezing (folding) test at drum can scale.
(Drum can scale: Φ approx. 600mm, approx. 1/25th size)⚫ The shape of the two-pronged fork was changed to verify the final squeezed (folded)
shape it would produce.

Lower down

Shapes of two pronged forks to be tested
Upper drum canRaise

Squeeze

Squeeze

Upper drum canUpper drum can
Negativepressure

Lower drum can

Two-pronged fork (not finalized)
Isolation sheet[1] Raise the upper drum can(pull out the isolation sheet)

Lower drum can[2] After pulling out the isolation sheet,the sheet is pushed in with the twopronged fork (not finalized shape) as theupper drum can is being lowered

Lower drum can[3] Check the shape of thesqueezed isolation sheet©International Research Institute for Nuclear DecommissioningY-shaped two-pronged fork

6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination(b) Testing plan

No.63

U-shaped two-pronged fork

Backwards C-shaped
two-pronged fork

[Basic test: (Plan A) Simply squeeze toward the center]⚫ The test was performed in negative pressure conditions (-450 [Pa]) using the twopronged fork on the right.

Shape of the prepared two-pronged forks
Isolation sheet

From a 90 degree direction
Push in (assistance)

U-shaped two-pronged fork
Squeeze
Y-shaped two-pronged fork

Squeeze

From a 90 degree direction
Push in (assistance)
The isolation sheet is sandwiched
between the two-pronged forks

Squeeze

Squeeze
Backwards C-shaped two-pronged fork

Squeezed with two two-pronged forks=> When two two-pronged forks are used, the isolation sheet may getcaught between the two-pronged forks

⚫
⚫
⚫
⚫

Squeezed with two backward C-shaped two-pronged forks,
with two U-shaped two-pronged forks assisting=> With assistance from the 90 degree directions, the sheet won’t
caught between the forks

The sheet was able to be squeezed toward the center with two two-pronged forks.
There is a possibility that the isolation sheet could get caught between the two-pronged forks when using only
two two-pronged forks. With assistance from the 90 degree directions, the sheet won’t get caught between theforks.
The shape of the sheet squeezed in the center is not reproduceable and differs each time; the gaps between
the sheets and the degree to which they overlap cannot be controlled.
Squeezing the sheet by winding rope around it was considered but had the same issues as the above.

Rope

Squeezing with rope©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.64(b) Testing plan
[Basic test: (Plan B) Folding so that the sheets do not overlap①]⚫ The test was performed in negative pressure conditions (-450 [Pa]) using the T-shaped two-pronged fork.
Wrinkly all over

Wrinkled at the edges
Isolation sheet

T-shaped two-pronged forks (topand bottom)
・The plan is to weld them
together・The other side will be pushed inusing the same tools

Squeeze

It was folded as the drum can was lowered=> The wrinkles spread all over⚫

⚫
⚫

The drum can was fixed and the isolation sheet was manually pulled
out and folded=> The edges were wrinkly and the other parts of the sheet were folded

When the isolation sheet was pulled out and folded as the drum can was being lowered, the isolation sheet could not be folded
adequately and the sheet was wrinkly all over. (The isolation sheet was folded over one another.)
When the drum can was fixed in place and the isolation sheet was pulled out and folded using two-pronged forks, the wrinkles
were mainly focused on the edges and the areas other than the edges were folded into two.
At the same time, because the sheet was folded over itself many times at the edge, pushing in the edges and folding the isolation
sheet was considered.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(b) Testing plan
[Basic test: (Plan B) Folding so that the sheets do not overlap⚫ A test was performed under negative pressure conditions (-450 [Pa]) using a Tshaped two-pronged fork and a pushing jig.

No.65
Direction thatthe sheet will
be pushed in

Pushing jig shape (tentative)

T-shaped two-pronged fork

Squeezing jig

Isolation sheet

Pushing the sheet in

Fold the sheet using the pushing jig together with the fork⚫

Using the pushing jig to push in the isolation sheet from the 90 degree directions, the isolation sheet was able to be folded asshown in the illustration.
⚫ While the gaps and the level of overlap between the isolation sheet seem to be controllable somewhat, reproducibility is an
issue.
⚫ Because as much as 12 isolations sheets were overlapping in the area where there was the most overlap, the welding
conditions should be set such that the minimum thickness (2 sheets worth) and the 12 isolation sheets together are both
weldable.
(The maximum number of sheets that could overlap is less than at the edge described in [1] above.)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.66(b) Testing plan
[Basic test: Results and challenges]⚫ The test results have been organized as follows.
ID.

1

2

3

Item

Ability to squeeze(fold)

Shape after it issqueezed (folded)

Evaluation andchallenges

Plan A: Simply squeeze toward the center

Plan B: Fold so that the sheets do not overlap

Can be squeezed by squeezing toward the center with
two two-pronged forks and with another two two-pronged
forks from the 90 degrees direction.

[1]: By fixing the drum can in place and pulling out theisolation sheet with a T-shaped two-pronged fork as it isfolded, the wrinkles mostly end up on the edges, and the
sheet, except for its edges, can be folded into two.
[2]: By pushing in the isolation sheet from the 90 degrees
directions using a push-in jig, the number of times the
sheet overlaps can be reduced compared to the edges in[1] above.

Bunched up in the middle.
(Mostly in an ellipse.)[1]: Folded into two, except for the edges which areoverlapping in multiple times (12 or more).
[2]: The whole sheet, including the edges, overlapping by
a maximum of 12 layers

・Because the isolation sheet is bunched up in thecenter, welding may only need to be performed one time.
・The shape of the center cannot be reproduced reliably
and the gaps between the sheets and the degree ofoverlap are difficult to control (welding conditions willneed to be studied).
・Because visual checking on how the squeezing isgoing difficult, checking after welding will also likely be
difficult.

[1]: The welding conditions for the edges need to be
examined.
The shape of the folds (especially at the edges)
cannot be consistently reproduced.
[2]: The gaps between isolation sheets and the degree ofoverlap seems somewhat controllable.
(Reproducibility continues to be an issue.)
Challenge shared between [1] and [2]:・It will be difficult to remotely verify the number of times
the sheet overlaps.

With Plan A, the number of welds required could be reduced and with Plan B, the difficulty of welding could be
reduced by controlling the degree by which the isolation sheet overlaps.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the
spread of contamination

No.67(b) Testing plan
[Element test]
The isolation sheet squeezing (folding) method verified in the basic test will be verified on a drum can scale and in a 1/4th scale toverify weldability and cutting performance.
[Test plan]
The verification items for the element test were organized as follows. The remote handling device will be manufactured in FY2023
or beyond. As such, sealability will only be measured as reference and this project will verify basic feasibility.
ID
.

Item

Details

1

Manufacturability⚫ Considering the size of the actual unit, the sheets will need to be joinedand enlarged, instead of manufacturing it as one unit.
⚫ The isolation sheet will be test manufactured to check its
manufacturability.

・Can be manufactured.

2

Storageperformance⚫ The isolation sheet will be stored outside of the work container andpulled out when it is going to be used.
⚫ The foldability of the sheet joint surfaces and whether the sheet can befolded to the calculated size will be verified.

・The sheet can be folded to the calculated size.

3

Weldability(Sealability)⚫ The isolation sheet will be squeezed (folded) and welded using aultrasonic wave welding machine.
⚫ After welding, water will be poured from the opening at the top of the
sheet to check for leaks from the welds. (Measurements to be taken as
reference.)

・Can be welded. （Welds will be visually inspected.)(The welds will be checked for leaks and results will be reflected onto
discussions on the method for folding the sheet using the remotely
operated device, shape of the horn to be mounted onto the remotely
operated device, and the method for welding using the remotely
operated device.)

4

Cutting
performance⚫ The welded isolation sheet will be cut with a ultrasonic wave cutter.
⚫ The cut surface will be checked. (The cutting time will be measured as
reference.)

・Can be cut.

Criteria

折り畳み・溶着
Fold/weld[Storage performance]

Cut
切断[Weldability/Cutting performance]©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.68(c) Test results[Manufacturability: Testing details]⚫ Because of the sheer size of the sheet when made in full-scale, the sheet will be difficult to manufacture as one
unified structure.
⚫ Because the same problem persists at 1/4th scale, the manufacturability of the sheet was verified using the
manufacturing method of joining sheets together to enlarge it. (The same method will likely be used whenmanufacturing it at scale.)⚫ 1/4th scale sheet dimensions: φ3500×5000[mm] (cylinder), thickness 0.2 [mm]
3500

5000

Sheet manufacturing method[1] Manufacture sheets with dimensions that are the final cylinder split into
12, lengthwise[2] Join the sheets (manufacture a cylinder)・Welding method: Overlapping welding using a high frequency welding
machine・Weld width: 10 [mm][3] Visually inspect the welds(verify by comparing them against a quality welding sample and a
defective welding sample)

Welds

1/4th scale sheet dimensions

Example of a quality
welding

Example of defective
welding(Not welded)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.69(c) Test results[Manufacturability: Testing details]⚫ In addition to the normal cylindrical sheet, an accordion-shaped sheet that takes into consideration its ability to be contained in acollection box, and a sheet made stronger with PET fibers was created for the φ3500×5000[mm] sheet with a thickness of
0.2[mm].
(PET: polyethylene terephthalate)
PET fibers

PET fibers(□1[mm] mesh)

Cylindrical sheet

Accordion-shaped sheet

Sheet with PET fibers⚫ It was confirmed that all three types of sheets could be manufactured without welding defects.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.70(c) Test results[Storage performance: Testing details]⚫ The isolation sheet will need to stored outside of the work container (collection box) and pulled out when it is going to be used.
⚫ Regarding the storage performance of the isolation sheet that is going to be contained in the collection box, partitions (width
250× height 850[mm]) were set up on the perimeter of the sheet, and the isolation sheet at 1/4th scale was lifted up and thenlifted down to check for foldability.
⚫ This was verified with the normal cylindrical sheet, the accordion-shaped cylindrical sheet, and the cylindrical sheet with PET
fibers.

Work container
Sheet pressing mechanism*

Isolation sheet

Collection box

Partitions

Collection box

Work container
Sheet lifted* A tube used in pressure adjustments and sponges were used in the drum can scale test, but further testing is required for the actual unit
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.71(c) Test results[Storage performance: Testing results]⚫ It was verified that the normal cylindrical sheet, the accordion-shaped cylindrical sheet, and the cylindrical
sheet with PET fibers could all be folded smoothly (can be collected within the partition) just by lifting up andlifting down the sheet.
⚫ There were no great difference in foldability, and the joints of the sheets from when the sheets were
manufactured (welds) did not have a large effect on foldability.

Normal cylindrical sheet

Sheet with PET fibers⚫ Because there was no major difference, it was decided that the normal cylindrical sheet (including those withPET fibers) would be used in future testing.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.72⚫ Welding/cutting tests
・For the welding tests, tests for setting conditions were first performed.
・A sheet at 1/4th scale was used as the test body for the test for setting conditions, and the following were
implemented.
ID.

1

2

Verification
items

Weldability

Cutting
performance

Details⚫ A polyurethane simple cylindrical sheet at 1/4th scale (Φ3500×H5000[mm], thicknessof 0.2[mm]) was used to manually simulate the number of times the sheet would
overlap (shape of the folds) in normal pressure conditions, and to weld it using an
ultrasonic wave welding machine (manual work).
<Simulated shape>
Shape where the sheet is folded (squeezed) as much as possible while minimizing
the number of times it overlaps⚫ Welding is performed by moving the cylindrical sheet with the welding machine fixedin place.
[Notes]・The horn to be welded is around 200 [mm] in width and the welding width is around3500 [mm] (for a sheet at 1/4th scale) and the number of layers that overlap depend on
the location (2, 4, 6 sheets may overlap).
・The welding conditions for when the number of layers differ and horn joint surface
welding conditions will be verified.
⚫ The welded isolation sheet will be cut with a ultrasonic wave cutter.
⚫ The cut surface will be checked.
⚫ Water will be poured from the top opening of the upper part of the sheet (hydraulichead pressure of 400 [Pa] or more assuming the negative pressure of the actual unit,
and a hydraulic head pressure of 500 [Pa] *1.5 to account for a margin of error) tocheck for water leaks from the welding and cutting surfaces.

Criteria

・Visually check the weld and ensure
there are no issues.
(Check by comparing the weld against
good welds and bad weld samples.)・There should be no water droplets on
the weld surface.
(To be checked during the water leakcheck performed in ID.2)

・It should be cut within the weld
surface.
・There should be no water droplets on
the weld surface.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination(c) Test results

No.73[Equipment configuration]⚫ The raised sheet was sandwiched between the horn and theclamping jig, and welded.
⚫ During the welding, the sheet fixing jig was used to fix the sheet
in place to ensure it would not move.

Sheet fixing jig
Overview of the welding test

Isolation sheet
Ultrasonicwave welding
machineClamp
Clamping jig

Oscillator

Welding testing deviceHorn(width 200 [mm)Clamping jig

Horn

Sheet fixing jig
Enlarged horn

Note: The horn and clamping jig in the photos are one example of what could be used in the actual work

Welding(checking the welding conditions)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination
Ultrasonic wave welding machine(Receiving side)(c) Test results⚫

No.74
Isolation sheet

Welding condition setting test procedure

Direction the isolation
sheet is moving in

Clamp
Isolation sheet

Clamping jig

Horn

Isolation sheet[1] Fold the isolation sheet(manually)

Ultrasonic wave
welding machine(Horn side)

Direction the isolation sheet
is moving in

Ultrasonic wave welding machine(Horn side)[2] Raise the isolation sheet

Direction the isolation sheet is moving in[3] Prepare for the isolation sheet to be welded(Sheet is moved toward the reader andclamped in place)

Welds

Ultrasonic wave welding machine(Clamping jig side)[4] Weld the isolation sheet (repeat the process of clamp-> weld-> move sheet)[5] Welding of the isolation sheet is completed©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.75⚫ Welding procedure
Move horn to the front, set the sheet in its place

Clamp the sheet (fix)Weld (emit the ultrasonic wave)
Cool (natural cooling)

Move back the horn
Unfix the sheet clamp

Isolation sheet

Clamp

Teflon tape

Clamping jig

Horn

Clamp

Move the sheet so that the next welding
location aligns

Sheet welding©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.76⚫ Movement of the test body and the horn・Because the drum can scale test found that the when folding the sheet, it could overlap by up to 12 layers, a test body that simulates 12
sheets overlapping was prepared.
3000[mm]Horn (example)
30[mm]

2 layers
12 layers(2 sheets overlap) (12 sheets overlap)

200[mm]2 layers(2 sheets overlap)

6 layers(6 sheets overlap)

2 layers(2 sheets
overlap)[2] 100[mm]

START

END

[3]

Welding line
[1] 50[mm][1] Starts with the horn sticking out of the sheet by 50 [mm][2] After welding, the horn moves to the right by 100 [mm] to weld again (overlaps by 100 [mm])[3] [2] above is repeated to weld to the edge of the sheet©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination(c) Test results

No.77⚫ Welding conditions
・Horn pressing force: 0.5 [MPa]・Welding time: 5[s]・Number of welding performed for each welding area: 1
・Cooling time after welding: 120 [s]⚫ Cut area after welding

Horn shape (mountain-shaped)[This test][Plan for the actual unit]
Weld

Cut

In the current plan, the upper, mid-level andlower lines will be welded and the sheet will be
cut at the middle welding line center.

Welding pitch
40[mm]Cut

In this test, the two are welded at a welding
pitch of 40 [mm] and it is cut at the centerof the lower weld line.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.78(c) Test results⚫

Welding condition setting test results
・The lower weld line was cut using a ultrasonic wave cutter and an airtightness (water leak check) test was performed.
・Water leaked from the area with two layers area (receiving jig side).
->Overwelding was estimated to be the cause.

Water leak testing

Ultrasonicwave cutter
Water leaking

Reference: Sheet before cutting©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination

Welds(c) Test results⚫

Measures
・The risk of overwelding increases as the welding time per weld increases.
-> Reducing the welding time and increasing the number of welds performed (weld thesame location after it has cooled) was considered.
In addition to the above, the amount by which the welds overlapped was revised andwelding conditions were revised as follows.

Molten resin ispoking out

Example of overwelding

Before revision

After revision

Horn pressing force [MPa]

0.5

0.5

Welding time [s]53Number of welding performed foreach welding area [times]

1

2

Cooling time after each weld [s]

120

120

Amount of weld overlap [mm]

100

10

Illustration

No.79

Hole

Weld
↓
Weld in turns moving
100 [mm] each time

Weld twice at the same
location↓
Weld twice at the same
location but having the edge
overlap by 10 [mm]-> Performed drum can tests using the revised conditions.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.80(c) Test results⚫ Welding/cutting test at drum can scale・Based on the results of the conditions setting test, the following welding/cutting test was performed.

ID.

1

2

Verification
items

Details

Weldability

After fixing the sheet in place using the following method, the sheet will be removed fromthe drum can while keeping it fixed and welded with a ultrasonic wave welding machine＜Fixing method before welding>[1]Method where the cylindrical sheet is gathered (pushed in) and squeezed to thecenter using a two-pronged fork
[2]Method where the sheet is folded minimizing overlap as much as possible⚫ Welding is performed by moving the cylindrical sheet with the welding machine fixedin place.

Cutting
performance⚫ The welded isolation sheet will be cut with a ultrasonic wave cutter.
⚫ The cut surface will be checked.
⚫ Water will be poured from the top opening of the upper part of the sheet (hydraulichead pressure of 400 [Pa] or more assuming the negative pressure of the actual unit,
and a hydraulic head pressure of 500 [Pa] *1.5 to account for a margin of error) tocheck for water leaks from the welding and cutting surfaces.

Criteria
・Visually check the weld and ensure
there are no issues.
（Verified by comparing it against thegood welding and defective welding
samples.)・There should be no water droplets on
the weld surface.
(To be checked during the water leakcheck performed in ID.2)
・It should be cut within the weld
surface.
・There should be no water droplets on
the weld surface.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.81⚫ Drum can squeezing, welding, cutting test

[1] Fold the sheet[2]Install the sheet in thecollection box[5] Install the sheet in the water seal
in the lower drum can[3] Install the collection box in theupper drum can[6] Depressurize (-450 [Pa])[4] Install an airtight tube in theupper drum can[7] Fold (or squeeze) sheet(The photo describes the process when the sheet is folded.)*Attach the tube to the inside of the sheet (gap between the collection box and upper drum can), inject air into it, and seal
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.82⚫ Drum can squeezing, welding, cutting test
[Method where the sheet is folded to minimize overlap][Method where the sheet is squeezed to the center][8] Remove sheet, prepare for welding[9] Weld using ultrasonic waves[10] Cut using a ultrasonic wave cutter©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.83⚫ Drum can squeezing, welding, cutting test
[Method where the sheet is folded to minimize overlap]
・Welding was performed using the conditions before and after the revisions as verification.

Welding using welding conditions before revision
・Under the welding conditions before revision, water leaked out from above the weld line (outside) of the two layered portion similarly
to what occurred in the test for setting conditions.
・Water did not leak under the revised welding conditions.
・It is assumed that the damage received by the sheet was reduced by reducing the welding time for each weld and welding a second
time after the first weld had cooled.
In addition, for areas where the were different thicknesses (2 to 12 layers), it is thought that the thinner area was welded when the
thicker area was welded first, reducing the thickness and the difference in thickness between the thinner area.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination(c) Test results

No.84
Welding conditions
Welding conditions for squeezing⚫ Drum can squeezing, welding, cutting test
[Method where the sheet is squeezed to the center]• Welding was performed following the welding conditions on
the right.
• Welding was performed a second time as visual inspection
after welding found the weld was insufficient.
• The welds were visually checked after the second welding,and it was determined that welding was complete.
(It was determined that further welding was unnecessary
as smoke emitted during the second welding.)• No water leaks was detected in the water leak test after the
sheet was cut.
• However, the drum can was at 1/25th scale and it was
assumed that welding a sheet squeezed at scaleconsidering its thickness would be difficult.

Insufficient
weldingGood
welding

Horn pressing force [MPa]0.5

Welding time [s]5Number of welding performed foreach welding area [times]

1

Cooling time after each weld [s]120Amount of weld overlap [mm]―(Not needed as the sheet will besqueezed to below horn width)

Not yetweldedWelds

Example of insufficient welding(Transparency is high on the left, but the insufficient welded area is lesstransparent, and the unwelded area is semitransparent.)

Water leak test
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development ofisolation technology to prevent the spread of contamination(c) Test results

No.85⚫ 1/4th scale welding and cutting test: Squeezing method
・Though it was assumed that welding a 1/4th scale sheet squeezed
would be difficult based on the drum can scale test, welding was
performed on the squeezed sheet as verification.
Squeezing

Squeezing

Photo from the side

3,500[mm]
150[mm]Squeezing cross section

Diagram from above
・The sheet was sandwiched by devices from the left and right and squeezed with the assistance of people from 180° directions.
・The sheet was able to be squeezed such that the major axis of the final ellipse formed by the sheet (150[mm]) was less than the widthof the horn (200[mm]).
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.86(c) Test results⚫ 1/4th scale welding and cutting test: Squeezing method
・Verification of weldability-> Because the squeezed sheet is thicker than the sheet at drum can scale, it was welded by pressing the horns into thesqueezed sheet from the left and right.
Ultrasonic wave
welding

Ultrasonic wave
welding

Ultrasonic wave
welding
Welding horn

Welding horn

Welding horn

Welding horn

Welding horn

Thin

Sheet

Thick

Horn

Horn

Molten surface

Welding
The horn presses in while melting the resin through ultrasonic wave welding

・Insufficient welding occurred in the center where thesheet was thick and defective welding occurred in thethin edges.
-> The challenge is finding the optimum conditions.
Because squeezing at scale is also expected to bedifficult, the discussion assumed that the folded sheet
would be welded.

Leaks from the edges (welding defects)
Leaks from the inside (welding defects)

Checking for leaks©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.87(c) Test results⚫ 1/4th scale welding and cutting test: Folding method
・The sheet at drum can scale has been folded so it doesn’t overlap, welded, and checked for leaks.
・In the above case, the sheet was folded by pressing in on it from four directions (like a cross), but the sheet shape was improved so thatit could be folded by just pressing in on it from two directions (like in a straight line).
-> The foldability of the sheet designed so that the length that could be pulled out differs by direction (shape where the center portion of
the sheet can be pulled out but the edges can’t) was verified at drum can scale.
90°

The sheet can be pulled out
at the center.

270°

Side fixed to the upper drum can(Storage side in the collection box)
270°
180°

0°
90°

0°

180°

The sheet cannot be pulled out
at the edges.

360°
(0°)

Sheet illustration

Sheet net

Side fixed to the lower drum can(Side fixed to the water seal)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.88⚫ 1/4th scale welding and cutting test: Folding method[Foldability verification at drum can scale: Comparison at negative pressure]

Just in negative pressure (-450[Pa]), the sheet, except for theedges overlap in two layers.
The sheetnarrows in thecenter.

Normal sheet shape

Newly developed sheet shape

・The normal sheet at negative pressure (-450 [Pa]) narrows in the center.
・The newly developed sheet overlaps in two layers except at the edges just from being at negative pressure.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results⚫ 1/4th scale welding and cutting test: Folding method[Foldability verification at drum can scale]

No.89

Side fixed to the upper drum canUpper drum canSide fixed to the upper drum can (After folding)

Direction from which
the sheet is pushed

Lower drum can

Checking foldability

Side fixed to the lower drum canSide fixed to the lower drum can
Sheet after welding (before cutting)・It was confirmed that the sheet could be folded just by pushing from two directions (like in a line).
-> Compared to the regular sheet, less effort is needed to fold the sheet.
・This folded sheet did not differ significantly from the sheet folded by pushing from four directions (like in a cross).
-> This sheet shape will be used at 1/4th scale in the negative pressure test.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination(c) Test results

No.90⚫ 1/4th scale welding and cutting test: Folding method
・Test details
The following welding/cutting tests were conducted using the sheet designed so that the length that could be
pulled out differs by direction verified in the drum can test.

ID.

1

2

Verification
items

Details

Criteria

Weldability⚫ A polyethylene cylindrical sheet made of thermoplastic resin at 1/4th scale(Φ3500×H5000[mm], thickness 0.2[mm]) is used and is fixed similarly to the actual
unit. The welding machine is moved to check for weldability.
⚫ The test is performed in an negative pressure environment.

・Visually check the weld and ensure
there are no issues.
・There should be no water droplets on
the weld surface.
(To be checked during the waterleak check performed in ID.2)

Cutting
performance⚫ The welded isolation sheet will be cut with a ultrasonic wave cutter.
⚫ The cut surface will be checked. (The cutting time will be measured as reference.)⚫ Water will be poured from the top opening of the upper part of the sheet (hydraulichead pressure of 400 [Pa] or more assuming the negative pressure of the actual
unit, and a hydraulic head pressure of 500 [Pa] *1.5 to account for a margin oferror) to check for water leaks from the welding and cutting surfaces.

・It should be cut within the weld
surface.
・There should be no water droplets on
the weld surface.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination
Isolation sheet fixing location(c) Test results⚫ 1/4th scale welding and cutting test: Folding
method[Testing device]
・The ultrasonic wave welding machine is placed on
a cart and the sheet is welded gradually from theedge.
・After welding is complete, a ultrasonic wave cutter
is placed on the cart and the sheet is cut.
(Imagine replacing the horn in the diagram on theright with an ultrasonic wave.)

No.91

Ultrasonic wave
welding machinecart runs backand forth

Roller for keeping the sheet in place (placed above and below)

Cover plate (clamping jig)

Plan view

Sheet

Sheet fixing jig

Horn(width 200 [mm)Isolation sheet fixing location

Ultrasonic wave
welding machine

Horn
Ultrasonic wave
welding machine

Welding

Cover plate(clamping jig)/sheet presser

Side view

Ultrasonic wave welding
machine cart goes backand forth©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination

No.92(c) Test resultsHorn⚫ 1/4th scale welding and cutting test: Folding method[Photo of the testing device]

Horn location adjustment mechanism

Sheet fixing jig

Sheet

Roller for keeping the sheet inplace (placed above and below)

Ultrasonic wave welding machine(Oscillator)

Horn

Enlarged view of the horn

Expanded view of the ultrasonic wave welding machine side

Cover plate (clamping jig) side
Sandwich the sheet from the left andthe right with carts

Sheet
Ultrasonic wave
welding machine
Ultrasonic wave welding
machineCart goes back and forth
Roller for keeping the sheet in place(Though not in the photo, anotherroller exists below)

Plan view

Welding machine side
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination

No.93(c) Test results⚫ 1/4th scale welding and cutting test: Folding method[Test conditions]
・A 1/4th scale test was conducted using the welding conditions revised based on the results of the test for setting conditions and drum
can scale tests.
Horn pressing force [MPa]0.5

Welding time [s]3Roller: for folding and fixing the sheet
A

Number of welding performed foreach welding area [times]

2

Cooling time after each weld [s]120Amount of weld overlap [mm]10Welding
receiver

Welding
machineA

Illustration

Weld twice at the same
location↓
Weld twice at the same
location but having the edge
overlap by 10 [mm]・In the actual unit, rollers on the top and bottom of cart as seen on the right fix
the sheet in place and the welding machine on the cart goes back and forth.
・In this test, the cart (roller) and welding machine parts were prototyped.
-> The test results in addition to the procedures for the actual unit will beshown in the next slide onwards.

RollerSheet cutter
Welding machine
Weld repair device
Sheet fixing jig(for welding)High adjustingmechanism
A-A arrow view

Actual device• The sheet is fixed in place with the roller at
the front edge of the cart.
• The welding machine, sheet cutter, weld
repair device goes back and forth to weld,
cut, and repair the sheet.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology
to prevent the spread of contamination

No.94(c) Test results⚫ 1/4th scale welding and cutting test: Folding method[Testing procedures and results]<Procedures for the actual unit>

Work container
New isolation
sheet

New isolation sheetWork
container

Roller: for folding and fixing the sheet

Shielding cart
Transfer cart(3) Move the transport andshielding carts(1) Lift up the work container<Testing procedures>(1) Lift up the work container(Sheet is installed)

Inside of the sheet is set at
negative pressure

Cart moves (Sheet is folded)(2) Set the atmosphere inside the sheet to negative
pressure, move the cart
(Fold the sheet)

Welding
receiver

Welding
machine(2) Weld the isolation sheet

Expanded view of the weld line

(3) Weld the isolation sheet<Differences between the actual unit>
・The isolation sheet was hung from a diskthat simulates the bottom of the work
container
・The collection part of the isolation sheet
was not simulated

・The negative pressure inside thesheet was simulated
・The cart was manually moved
・The cart pulling out the sheet was not
simulated, and the sheet was fixed・The ultrasonic wave welding machine was prepared(assuming that a similar welding machine (that also canmove back and forth) will be used in the actual unit)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination

No.95(c) Test results⚫ 1/4th scale welding and cutting test: Folding method[Testing procedures and results]<Test results><Procedures for the actual unit>

Water injected (colored)First weld line

New isolation sheet(4) Cut isolation sheet<Testing procedures>

Second weld line

Ultrasonic wave cutter
Water leak test(4) Cut isolation sheet

Enlarged view of the cut
surface<Differences between the actual unit>
・The ultrasonic wave welding machine was replaced with the ultrasonicwave cutter to conduct this.
(In the actual unit, the welding machine, cutter, and repair device will beplaced in parallel.)

Water leaking(Water is leaking from the small holes)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology
to prevent the spread of contamination(c) Test results

No.96⚫ Summary of test results, issues and action policy
ID.

1

2

3

Item

Test results

IssuesAction policy

Manufactura
bility・It was verified that a φ3500×5000[mm]cylindrical sheet could be made using a
manufacturing method where sheets are joined
together to enlarge it.
・It seems that sheets of other sizes could bemade using the above manufacturing method.
・It was verified that a φ3500×5000[mm] sheetwith PET fibers and 200×20[mm] sheet witharamid fibers could be made.

――Storageperformance・It was verified that the normal cylindrical
sheet, the accordion-shaped cylindrical sheet,and the cylindrical sheet with PET fibers could
all be folded smoothly.
・It was verified that there were no great
difference in foldability among the different
types of sheets, and the joints of the sheetsfrom when the sheets were manufactured(welds) did not have a large effect on foldability.

・Once the collection box for the actualunit is developed, whether the sheet could
fit into it will need to be verified.

・If the sheet doesn’t fit into the collection
box, the dimensions and the structure of thecollection box will be reviewed.

[Issues with the [1] Method where thesheet is squeezed to the center]・At 1/4th scale, the center becomes tothick and the difference between the thinedges become too large, making it difficult
to set appropriate welding conditions.

[Action policy for issues with the [1] Method
where the sheet is squeezed to the center]

Weldability(Sealability)[Squeeze (fold)]・It was verified in the drum can scale test, thatsqueezing (folding) as described below ispossible.
[1] Squeeze to the center[2] Fold to minimize overlap[Welding verification:[1] Squeeze to the center]・Though the sheet was able to be welded atdrum can scale, in 1/4th scale, the welding in
the thicker center was insufficient and there
were welding defects in the thin edges.

・Because squeezing in the actual unit would
be difficult, the method of folding so that the
sheet does not overlap ([2]) will be pursued.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination(c) Test results

No.97⚫ Summary of test results, issues and action policy
I
D
.

3

4

Item

Weldability(Sealability)

Cutting
performance

Test results[Welding verification:[2] Fold to minimize overlap above]
・Because there are discrepancies in thenumber of times the sheet overlaps, that the
sheet could be welded at drum can scale wasverified by setting welding conditions that
accommodate minimum two overlapping layers
and the maximum 12 overlapping layers.
・Taking into account the actual unit, a sheetthat could be folded by pressing from two
directions (in a straight line) instead of four
directions (in a cross) was developed (the lengththat is pulled out was adjusted for eachdirection).
It was verified that it could be folded asplanned (in the same shape as [2] above) at
drum can scale.
・At welding test was performed at 1/4th scale.
It was verified that the sheet could be welded by
fixing the sheet in place with the cart rollers.
Though the weld lines were connected, there
were some areas where the line had warped
upward and downward. A water leak test foundthat there were small leaks where water droplets
would appear.
・The cutting performance of the weld of the
sheet with fibers was verified with a ultrasonicwave cutter.
・The tip of the ultrasonic cutter was aligned
manually.

IssuesAction policy[Issues with the [2] method where thesheet is folded to minimize overlap]
・Considering the possibility of welding
failing, inspection and repair methods willneed to be discussed.
・Though the sheet designed so that thelength that could be pulled out differs bydirection could likely be folded bypushing it in in a straight line, in theactual unit and with the current method(lowering down the sheet evenly), folding
may not be possible.

・There are issues with adjusting the
cutting position including with fixing the
sheet in place.

・A flow chart of the welding,inspection, repair, cutting processes
was created.
(See the next slide)・The method for pulling out the sheet
and other methods will be discussed
when fleshing out the design of thecollection box.

・Methods for adjusting the cutting
position including with fixing the sheet
in place will be discussed.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination(c) Test results

No.98⚫ Summary of testing results, issues, and action policy: Welding, inspection, repair and cutting process

Start welding
・Height・Across

Position horn

Weld

Move horn

Weld・Initial weld: use existing welding conditions
・Reweld (welding performed when welding is found to be
insufficient in the inspection below)->Rewelding conditions need to be discussed laterNo
Is it in the completion position?
Yes
Inspection

To the inspection
RepairReweldCut©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation
technology to prevent the spread of contamination

No.99(c) Test results⚫

Summary of testing results, issues, and action policy: Welding, inspection, repair and cutting process

Reweld(to the previous
slide)

Weld

Weld

Verify the weld with the camera

Insufficient

溶着不足
welding

溶着OK
WeldedNot yet未溶着
weldedWelding
溶着部partOver-welding

Inspection
RepairInsufficient welding
Inspection[1] There are holes or scratches(can be clearly detected by eye)

No issues

Example of insufficient welding[1] Welding surface is thin(compare with photo sample)[2] There are gaps between the welding lines[2] There are molten clumps(compare with photo sample)

Reweld the relevant part

MoltenclumpsTo cutting
Welds

Cut

To repair

Examples of molten clumps©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.100(c) Test results⚫

Summary of testing results, issues, and action policy: Welding, inspection, repair and cutting process
Weld

Inspection

Inspection

RepairCheck the differential pressure
inside the work containerLess than thethreshold*

Fluctuations beyond the threshold*(leaks)Repair relevant part・Duct seal tape repair

Cut

Install an ultrasonic wave cutter on the axis by which
the cart goes back and forth to cut the sheet

The work container is loaded onto the transport cart and is madeairtight with the water seal of the transport cart.

*: The threshold and criteria needs to be discussed further. Before the isolation
sheet is welded, the dust concentration in the work container and PCV could havefallen to be on par with the work area inside the R/B (level at which staff can workwith just a full-face mask); after measuring the dust concentration, setting a criteriathat allows for some leakage will be considered.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination(c) Test results

No.101⚫ Comparison of the drum can scale and 1/4th scale tests and issues at full scale (1/2)
ID.

1

2

Item

ManufacturabilityStorageperformance

Drum can scale (1/25th scale) test

・Verified it could be manufactured.

・It was verified that it could be stored within thecollection box.

・It was verified that squeezing (folding) as
described below is possible.
3

Weldability(Sealability)[1] Squeeze to the center[2] Fold to minimize overlap
・It was verified that folding is possible for bothand that there are no water leaks.

1/4th scale test
・Verified that a φ3500×5000[mm]cylindrical sheet could be made using a
manufacturing method where sheets arejoined together to enlarge it.

・It was verified that the sheet could befolded just by lowering it down, and thejoints of the sheets from when the sheets
were manufactured (welds) does not have alarge effect on foldability.

・At welding test was performed at 1/4th
scale. It was verified that the sheet could be
welded by fixing the sheet in place with thecart rollers. However, though the weld lines
were connected, there were some areas
where the line had warped upward anddownward.

・A water leak test found that there were
small leaks where water droplets would
appear.

Issues at full scale
・Because it has been verified that the sheet could bemade even larger by joining sheets together,
manufacturability doesn’t seem to be an issue.
・Under current assumptions, a sheet with PET fibers
seem viable. However, once the actual device isdeveloped, the required strength for the sheet will beverified again. If the sheet with PET fibers is not strong
enough, other measures, such as manufacturing a sheetwith aramid fibers will be considered.
・The storage performance of the sheet itself will likely
remain a non-issue even if the scale increases.
・However, once the collection box for the actual unit isdeveloped, whether the sheet could fit into it and whether
it can be easily pulled out will need to be verified.
・It is assumed that the way both the 1/4th scale and fullscale sheets layer from two layers (2-sheets’ worth of
thickness) to 12 layers (12-sheets’ worth of thickness) willremain the same.
(Though the thickness of the overlapping portion will
increase by four-fold, only the number of welding
required will increase. The welding conditions for twolayers and 12 layers will be the same and can be appliedin the actual sheet.)
・A full scale transport cart needs to be prototyped andwelding machines and other device installed in the cart toverify weldability and sealability under a device
configuration similar to the actual unit.
・Because the collection box was not manufactured forthe 1/4th scale test, when designing the collection box,
the method by which the sheet is pulled out will need tobe reviewed and methods other than the pull out method
will need to be considered.
©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.102(c) Test results⚫ Comparison of the drum can scale and 1/4th scale tests and issues at full scale (2/2)
ID.

4

Item

Cutting
performance

Remarks

Drum can scale (1/25th scale) test
・It was verified that the sheet could besmoothly cut with a ultrasonic wave
cutter.

1/4th scale test

Issues at full scale

・The cutting performance of the weld of
the sheet with fibers was verified with aultrasonic wave cutter.

・A full scale transport cart needs to be
prototyped and a cutting device (ultrasonicwave cutter) installed in the cart to verify
under a device configuration similar to theactual unit (issues in adjusting the cutting
position, including fixing the sheet inplace.)

・However, the tip of the ultrasonic cutter
was aligned manually.

・Though manufacturability and storage
performance are not part of the test items,
the sheet was manufactured and stored
within the collection box as verification of
the weldability.

©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.103(c) Test results⚫ Contamination area classification and application based on the testing results.
The contamination area classification will be as described in No.17. Therefore, the classification will be applied as follows based on thetest results.
・The measurements of the dust concentration within the PCV when cutting AWJ in the Unit 1 PCV detailed internal investigation shows that the dust
concentration may rise up to 10-2[Bq/cm3] during cutting but falls down to below 10-3[Bq/cm3] a few hours later. (See the next slide)・Welding and cutting of the isolation sheet will be performed after the cut components are stored by the work container. Before the work container
is removed, the dust concentration within the PCV is measured to check that it is below 10-3[Bq/cm3], only after which the welding and cutting of theisolation sheet will be started.
・The above dust concentration level will be at the same level as the work area within the R/B (level at which staff can work with just a full-face mask)
and even if the PCV gas leaks to the operation floor side, it is assumed that it could not lead to contamination that could negatively affect work by staff.
・It is more important to prevent shards and dust particles from cutting that has been stored within the work container from dispersing to the operation
floor, than to prevent PCV gas from leaking, from operation floor contamination mitigation perspective.To prevent this, the isolation sheet will bewelded in three lines from the top, and the center of the middle weld line will be cut.

連絡通路
Passageway(Primaryboundary)(一次バウンダリ)

G

Work
作業容器
container（遮蔽）(Shielding)-150[Pa]*

Isolation
隔離シート
sheet
（気密）
(Air-tight)

Shielding cart

R

増設建屋
Additionalbuilding(Secondary boundary)(二次バウンダリ)YClosing lid
遮蔽台車
Shieldingcart

R/B, building cover
R/B・建屋カバー(Secondary
boundary)(二次バウンダリ)・A closing lid will be placed on the
opening once the work container iscarried out.
・The closing lid is used to ensure it isairtight and the shielding cart shields it.

R

In this diagram, the work container is on a level
below the operation floor. However, as describedin previous steps, but the most promising plancurrently being considered does not lower thecontainer from the operation floor.

[Note]
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 R, Y and G, and the
red zone is marked with a red border.
The red zone is marked with a red border.

The contamination area classes are subject to changeWork container
作業容器等のdecontamination
area
除染エリア

Transfer
cart
搬送台車

R
R

大型搬出容器Largetransfer containers-64[Pa]*-400[Pa]*G

Contamination area classification*Pressure values are estimates©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology toprevent the spread of contamination

No.104(c) Test results
Contamination area classification based on test results: Reference material for dust concentration inside the PCV

4.1 On-site demonstration of access route establishment
4.1.1 On-site demonstration - cutting: Response when cutting AWJ (e.g., whencutting gratings)
Operational value

Monitoring items
Dust concentrationin the PCVApplication in field work

1.7 x 10 -2 Bq/cm3 or less
Dust concentration on the upstream side of the gas
management system

Set the following cutting start time according to the increases
in dust concentration (Diagram-1)

Pressure inside
the PCV

0.8kPa or lessSet the continuous cutting time according to the initial internalpressure within the PCV (Diagram-2)
If pressure reaches 0.75 kPa, halt cutting.

Temperatureinside the PCV

100℃ or lessCutting 10 minutes before or after the PCV internal
temperature measuring time is prohibited

Start ofStart of first Start of second third
cutting
cutting
cutting*Average peak dust concentration when cutting the 350 A
inner door + 3σ
First
SecondExtrapolated value

Third
When starting cutting while checking dust behavior

Reduced due to adelay in theextension starttime

Operational value

Determinesecond cutting
according to theslope of the dust
curve

Determine third
cutting according to
the slope of the dust
curve

0.8 kPA arrival injection time

When cutting every 30 minutes

Dust
concentration⚫

AWJ continuous
cutting time
Permissible range

Delay start of cutting by 30
minutesTime

Diagram-1 Method for setting the following cutting start time according to theincreases in dust concentration

Initial internal pressure

Diagram-2 Relationship between the initial internal pressure and the 0.8 kPa arrival time

Source: FY2018 supplementary budget Subsidy Project of Decommissioning and Contaminated Water Management Development of Technology
for Detailed Investigation inside PCV (On-site Demonstration of Technology for Detailed Investigation Considering Deposit Measures)
FY2020 Final Report (August 2021)©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to prevent the spread ofcontamination(d) Risks and future issues

Extracting
risks in handling isolation sheets and their countermeasures
隔離シート取り扱い時のリスクの摘出及びその対応策について

No.

Step
ステップ

1

When
installing the
隔離シートベース
isolation
sheet base
設置時

The isolation sheet base moves (shifts) due to
地震等で隔離シートベースが動く(ずれる)earthquakes and the like.

Wheninstalling the
新規隔離シート
new isolation sheetbase 設置時
When
installing the
新規隔離シート
new isolation sheetbase 設置時

The isolation sheet gets caught when it is being pulled out
収納ボックスから隔離シートを引き出す際に引っ掛かり等でシート
Reflect the issue onto the collection
収納ボックスの設計に反映する。
box design.
from the collection box, and cannot be pulled out.
が引き出せない

2
3

No.105

リスク項目
Risk
item

Response
measure (tentative)対応策(案)
After
the isolation sheet base is installed, fix in place with
隔離シートベース設置後、アンカーボルト等で固定する。
anchor bolts and the like.

The isolation sheet rips when it is being held or
隔離シートの把持・引き出し時の破れ

Reflect the issue onto the collection box design and isolation
収納ボックス、隔離シート取り付け装置の設計に反映する。
sheet installation device design.

pulled out.

4

Wheninstalling the
新規隔離シート
new isolation sheet
設置時
base

Cannot be sufficiently attached to the water
水シール堰(フック等)への取り付け不良

シート側にハトメ、水シール堰にフックを取り付けておき、カメConsiderattaching eyelets on the sheet side and hooks on thewaterseal dike and installing and removing with a flexible
ラで確認しながら柔構造作業アームで取り付け、取り外しを
structurearm while checking with a camera.
実施する案を検討。

5

When
installing the
新規隔離シート
new isolation sheetbase 設置時

The existing isolation sheet could not be kept
既設隔離シートが押さえられず、炉内へ落下

作業容器内に搭載したアームで既設隔離シートを把持してConsiderholding and cutting the existing isolation sheet with
thearm mounted in the work container.
切断する案を検討。

6

When
folding, welding,
新規隔離シート折り
and cutting the new
畳み、溶着、切断時
isolation
sheet

Rupture in the isolation sheet when folding
折り畳み時の隔離シート破れA workaround will be found to ensure that the folding device
折り畳み装置にてシートが破れないような工夫をする方針で
does not rip the sheet; the details including the device will be
あり、今後装置含め具体化。
fleshed out later.

7

When folding, welding,
新規隔離シート折り
andcutting the newisolation
sheet
畳み、溶着、切断時

溶着不良
Insufficient welding(e.g., welding isn’t successful in the work place, the weld
(そもそも溶着がうまくいかない、構造物や水滴が落下して溶着箇
peels off due to falling components and water droplets.)
所が剥がれる等)

Consider welding conditions that allow areas where the sheet
シート厚さが異なる(2枚重ね、12枚重ね)部分も溶着可能な
thicknessdiffers (e.g., two layers and 12 layers) can be welded
溶着条件を検討し、溶着不良部についてはダクトシールテー
together,and consider repairing areas that were insufficiently
weldedwith duct seal tape. The welding, inspection, repair,
プで補修することを検討。溶着、検査、補修、切断のフローを
cutting
processes have been examined. The rest including the
検討した。今後、装置含め具体化。
device itself will be fleshed out later on.

8

When folding,・新規隔離シート溶着(切断)時、斜め方向等の想定外の方向に・When welding (cutting) a new isolation sheet, it welds (cuts) in a
新規隔離シート折り
welding,and cutting
unexpected
溶着(切断)direction such as the diagonal direction
thenew isolation
畳み、溶着、切断時・Welding/cutting device positioning accuracy
・溶着・切断装置の位置決め精度
sheet・Measures to be fleshed out further, including the device design. One
台車に搭載したローラでシート全体を固定し，装置の横行軸
idea is to fix the sheet with the rollers mounted on the cart, install weldingに溶着機や超音波カッターを設置して溶着(切断)部をカメラ
machines and ultrasonic wave cutters on the axis that the device willtraverse and to weld (cut) while checking on it with a camera.
で確認しながら溶着(切断)する等、今後、装置含め具体化。

9

Whenlifting the work
新規隔離シート溶着
container after theComponent falls when lifting the work container (sheet rips)
new後の作業容器
isolation sheet is 作業容器吊り上げ時の構造物落下(シート破れ)
吊り上げ時
weldedConsider selecting a high strength isolation sheet (is less likely to rip)
隔離シート強度が高いもの(破けにくいもの)を選定し、台車
and have it land on the water seal on the cart to prevent the spread of
上の水シールに着座させて汚染拡大防止を図ることを検討。
contamination.

10

When
lifting the work
新規隔離シート溶着
container after the
The isolation sheet gets caught by the cart when the work
台車に作業容器を載せた際に隔離シートが台車に挟まれる(シー後の作業容器new isolation sheet is container is loaded onto the cart (sheet rips)
ト破れ)welded
吊り上げ時

Consider selecting a high strength isolation sheet (is less likely to rip)
隔離シート強度が高いもの(破けにくいもの)を選定し、台車
and have it land on the water seal on the cart to prevent the spread of
上の水シールに着座させて汚染拡大防止を図ることを検討。
contamination.

11

After the work container is Isolation sheet on the reactor well side rips (due to fallen items
作業容器離脱後
原子炉ウェル側の隔離シート破れ(落下物、装置干渉等)
removedand interference from devices)

隔離シート強度が高いもの(破けにくいもの)を選定し、閉止that is less likely to rip) and use the closing to prevent the
蓋を着座させて汚染拡大防止を図ることを検討。
spread of contamination.

seal dike (e.g., hooks)

up and falls to in-core

Consider selecting a high strength isolation sheet (i.e. sheet©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination

No.106(d) Risks and future issues[Issues after FY2023]
This project performed element tests for isolation sheet welding/cutting and issues and response measures weredeveloped.
The following are the issues that need to be discussed in FY2023 and beyond based on these results.
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Design and test manufacture the remotely operated device that will fold the isolation sheet
Design and test manufacture the remotely operated device that will weld and cut the isolation sheet
Discuss inspection methods for during and after welding
Discuss criteria such as the threshold for determining leaks
Design and test manufacture a isolation sheet base such as a seal for installing the isolation sheet baseDevelop a device to hold and cut the existing isolation sheet within the work container and to collect it within thework container
Develop the structure of the collection box and test manufacture
Develop methods for installing and removing the isolation sheet to the water seal dike sheet seat, test
manufacture the water seal dike
Design and test manufacture of the above isolation sheet installation and removal device
Develop a device to collect the used isolation sheet using the large transfer container
Test manufacture the full-scale isolation sheet
Verify the feasibility of the collection box and water seal dike (e.g., perform element tests)
Verify feasibility through combination tests of the full-scale work container, full-scale collection box, and water seal
dike
Discuss operability and work procedures, including operator remote operation training©International Research Institute for Nuclear Decommissioning6. Implementation Items of This Project: 1) Development of isolation technology to preventthe spread of contamination(e) Summary

No.107➢ The boundary and contamination area classification were organized and the contamination areaclassification to be required for passageways were clarified.
➢ Technologies for containing contaminants when removing large components and transporting items(isolation mechanism) were studied. The opening and closing method, joining method, trap method, andshatter-proof method were studied and compared as isolation methods, and the joining method (isolation
sheet) was selected.
➢ The steps for isolation sheet construction were studied and organized. The requirements for each step
were organized and thermoplastic resin (polyurethane resin) was selected as a candidate based on its
joinability and cutting performance. The ultrasonic wave welding machine and ultrasonic wave cutter
were chosen as the joining and cutting methods for the isolation sheet.
➢ A basic test was performed at drum can scale (1/25th scale), and two methods—one method ofsqueezing toward the center and another method of folding so that it does not overlap— were studied.
After performing the test for setting welding conditions, welding and cutting tests were performed for bothmethods at drum can scale, and both methods were found to be weldable (no leaks were found in thefollowing water leak test). However, with the squeezing method, the center become thick and will be likely
too difficult to weld at full-scale; as such, the study was continued on the folding method.
➢ Welding/cutting element tests (1/4th scale tests) were performed using the folding method and issues
and response measures were studied. A flowchart of the welding, inspection, repair, cutting processes
was created and future issues were organized.

©International Research Institute for Nuclear Decommissioning7. Specific Goals and Progress Assessment for Achieving the Purpose of the Project1) Development of isolation technology to preventthe spread of contamination

TRL level

No.108[Goals]
The contaminants generated in the work and the routes by which these materials
spread will be clarified, and the contaminated area class for the passageways will beclearly specified. The isolation mechanism for preventing the spread of contamination(e.g., device, operational method) will be evaluated and selected from the perspective ofconfinement performance, certainty and workability of remote operations, robustness anddurability, efficiency of inspection and maintenance, and its field applicability will beassessed through element tests.
(Target TRL at end: Level 3)[Evaluation of level of achievement]
The contamination area classification was clarified, the isolation mechanism wasassessed and selected, and the field applicability for welding and cutting were verified
through element tests. Based on the test results, future issues to do with full-scale
implementation were organized. Based on the above, it is determined that the initial
goals were met. (TRL: level 3)
Explanation

Phase

TRL7

Stage where practical application is complete.

Actual operation

TRL6

Stage where field demonstration is performed.

Field demonstration

TRL5

Stage where a prototype at scale is manufactured and demonstrations are conducted infactories in an simulated environment.

Simulateddemonstration

TRL4

Stage where functional tests are performed at the test manufacturing level as part of thedevelopment and engineering process.

Application research

TRL3

Stage where development and engineering is performed applying and combining applicable
experience. Or the stage where development and engineering is performed using fundamental
data in an area where there is almost no applicable experience.

Applied research

TRL2

Stage where development and engineering is performed using fundamental data in an area
where there is almost no applicable experience, and requirements are set.

Applied research

TRL1

Stage where basic facts are being clarified about the target of development and engineering.

Basic research©International Research Institute for Nuclear Decommissioning