Subsidy Project of Decommissioning and Contaminated Water Managementin the FY2016 Supplementary budgets

Upgrading of Fundamental Technology for
Retrieval of Fuel Debris and Internal Structures
Accomplishment Report FY2017
April 2018
International Research Institute for Nuclear Decommissioning (IRID)
All Rights Reserved. International Research Institute for Nuclear Decommissioning©International Research Institute for Nuclear Decommissioning

No.1
1. Purpose and Goal of "Upgrading of Fundamental Technology for Retrieval of Fuel
Debris and Internal Structures"[Purpose of upgrading of fundamental technology for retrieval of fuel debris and internal structures]
Investigations to date suggest that nuclear fuel, melted down with reactor internals, formed fuel debris andaccumulated in the Reactor Pressure Vessel (RPV) and the Primary Containment Vessel (PCV) on 1F.
It will be a correct assessment that fuel debris in the RPV and PCV is in a sub-criticality state. Nevertheless, theentire nuclear plant’s condition is different from the intended original design and is unstable due to damage in thereactor building (R/B), RPV and PCV from the accident; therefore, it is necessary to stabilize the plant by retrieving
the fuel debris and keeping it in a sub-critical state as well as to prevent the diffusion of radioactive materials.
Given the above-mentioned circumstances, the project’s goal is to begin fuel debris retrieval, by 2021 or earlier,from any of the units chosen as the first target of this work. The project target is based on the "Mid-and-Long-Term
Roadmap towards the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station Units 1-4" (hereinafterreferred to as Mid-and-Long-Term Roadmap).
The program objectives are: to facilitate the smooth decommissioning and contaminated water treatment of the
Fukushima Daiichi Nuclear Power Station by supporting the development of necessary technologies according to the"Mid-and-Long-Term Roadmap" as well as the "Progress status of R&D projects and direction for next period" (39thmeeting, Secretariat of the Team for Countermeasures for Decommissioning and Contaminated Water Treatment), andto improve the level of science and technology in Japan.
Specifically, technologies to realize methods and equipment used to remove fuel debris and reactor internals will
be developed to support the selection and implementation of methods and technologies for fuel debris and reactor
internals removal. Focus will be given on top entry and the side entry methods for the technical development of fueldebris retrieval methods.

[Overall development goal]
The program will be executed with the aim of commencing fuel debris retrieval in fiscal 2021 on anyof the units chosen as the first target of this work based on the "Mid-and-Long-Term Roadmap."©International Research Institute for Nuclear Decommissioning2. Achievements of Projects Implemented Previous Fiscal Year (Years 2015-2016)No.2
Application Examples of Developed Basic and Fundamental
Technology(1/3)
Example of method

In-building gas
control system

In-building gas
control system

In-cell crane 2
Waste transfer area

In-cell crane 1: Device traffic line

Transfer cask collection area
Transfer crane 1
Equipment carryingin gate side
Canisterlifting crane 1○ Tests for platform and cells

Waste carryingout gate side

Canister lifting
crane 2

Manipulator/
airlock

Storage
Canister

Sealedcontainer
Canister setup
platform

Waste
carryingout door 1

Shieldcontainer

Sealed container
carriage

Airlockdoor: Fuel debris flow line

Transferring cask
inspection area

Waste
transfergate 2

Waste
transfergate 3

Shield container
carriage insidecellShield container
carriage outsidecellIn-building water
control system
3 m3/hFull time 100%
operation○ Tests for RPV access equipment

Pin

Lid tightening jig

In-building water
control system
3 m3/hFull time 100%
operation○ Fuel debris cutting and dust collection
technology

Applications shown in the figure are only examples. The method for applying the developed basetechnologies may be reviewed later. Element tests for technical issues identified in a conceptual
study were performed so that the test results would be useful even if methods are changed.

Container (and lid)

○ Tests for canister handling equipment©International Research Institute for Nuclear Decommissioning

No.3

2. Achievements of Projects Implemented Previous Fiscal Year (Years 2015-2016)
Application Examples of Developed Basic andFundamental Technology(2/3)○ Scale tests, development of lightweight shield structure
Former operation
floor surface

Flexible structure arm

Shield plug

Guide

RPV head nozzles

Shielding water pool (upper
part)
Well

Shielding water pool (lowerpart)
RPV head (1/4 scale model)
Areas reinforced by
Kevlar fibers

Equipment inside reactor
well

RPV insulationmaterial

PCV head handrail dismantlementi) [1] Scale tests, vi) [1] Lightweight shield structure

Equipment inside reactor
well

Verification test for accessibility to the
RPV insulation material for
dismantlement

The shielding water pool installedover the RPV head
Pressure vessel○ Development of RPV inner sealing technology
RPV inner sealing

Lifting mechanism (hoisting
attachment)

Shroud support

DSP

Processor

Fuel Debris
Arm of the processing tool
(Property of Hitachi-GE Nuclear Energy)

CRD housing

Full-scale mock-up of RPV internal structures

RPV inner sealing

Installation of RPV internal structures○ Development of fuel debris cutting technology
Alumina
Aluminaii) [1] RPV inner sealingvii) [1] Fuel debris cutting

Container⌀48 non-core bit
Common test facility processing status

Impregnated bit

Collected core

○ Development of flexible structure arm (Partial submersion-the side entry method)iv) [1] Flexible structure arm

Crane parts transportation status (pillar)

Horizontal cutting

Power supply connector connection©International Research Institute for Nuclear Decommissioning2. Achievements of Projects Implemented Previous Fiscal Year (Years 2015-2016) No.4
Application Examples of Developed Basic and Fundamental Technology(3/3)○ Tests of PCV welding equipment for remote welding work for sealing
Verification of basic feasibility of boundary construction between PCV and cell
Waste storage building

Waste canister

Canister storage
building

Equipment[3][2] MaintenanceCarrying
cell
In/Out Cell

Nitrogen atmosphere cell
Flow of Debris
Waste flow line
Equipment flow line

Reactor Building

Extension Building[5] Cask transfer cell
Unit can (UC) Storage Canister
Unit can/canister carrying-in[1] Debris
retrieval cell[4] Canister handling cell

Lid of transport cask

Manipulator
Manipulator
Inspection of
packing status

Movable door

Mini cask
Transport
Cask

Transfer system

Truck loading dock

Transport cask
carrying-in

Robot arm Unit can (UC)○ Tests for access equipment inside the pedestal
Verification of basic feasibility of robot arm and access rail

○ Tests for a hydraulic manipulator
Acquisition of basic data to build control logic
Fundamental test for robot arm development©International Research Institute for Nuclear Decommissioning

No.5

3. Project Overview
3.1 Collaboration with Other Projects
Upgrading of Approach and Systems
for Retrieval of Fuel Debris and Internal Structures

Approach and systems
for retrieval fuel debris
Characterization•Needs analysis/sharing of results

Upgrading the Comprehensive
Identification of Conditions inside Reactor• Cooperation with feasibility
verification of fuel debris
retrieval methods• Sharing safety requirements
and functional requirements

Development of Technology for Fuel Debris
Analysis/ Fuel Debris Characterization• Sharing Safety Scenario(During Water Leak Blockage
and Removal Work)• Cooperation in water
stoppage task steps

Upgrading of fundamental technology
Internal
Investigation
Development of Technology
for Investigation Inside RPVDevelopment ofTechnology for Detailed
Investigation inside PCV• Sharing Survey
Needs/Results

Sampling
Development of Sampling
Technology for Retrieval of
Fuel Debris and Internal
Structures

Development of Repair & Water
Leakage Stoppage Technologies for• Cooperation in packaging/Leak Locations inside PCVtransferring and methods Full-Scale Test of Repair & Water
Leakage Stoppage Technologies forLeak Locations inside PCV

Upgrading of Fundamental
Technology for Retrieval of Fuel
Debris and Internal Structures•Sharing safety scenario•Sharing Safety Scenario•Cooperating in(Large-Scale Earthquake)work steps

Seismic
Resistance
Development of Soundness
Evaluation Technology for
RPV/PCV

Water LeakBlockageTechnology• Cooperation incollection/transfer
and methods•Sharing safety scenario(Criticality Event)Criticality Control
Development ofTechnology for Criticality
Control Methods

Technologies forcollecting,transferring andstoring fuel debris
Development of Technology forCollection, Transfer and Storageof Fuel Debris

Solid Waste
R&D for Treatment and Disposal of
Solid Radioactive Waste©International Research Institute for Nuclear Decommissioning3. Project Overview

No.6

3.2. Basic Policy of Fundamental Technology Development
Main action policies for matters arising in connection with implementing the project plan are as described below.
[Basic Policy]
Policies for fundamental technology development shall be established based on the "Technological
Strategic Plan 2017 for Decommissioning of the Fukushima Daiichi Nuclear Power Station of TEPCO
Holdings, Inc." (hereinafter referred to as "Strategic Plan 2017"), which was formulated by the Nuclear
Damage Compensation and Decommissioning Facilitation Corporation. Details of the program anddevelopment themes shall be determined according to suggestions of the Strategic Plan 2017.

©International Research Institute for Nuclear Decommissioning

No.7

3. Project Overview
3.2. Basic Policy of Fundamental Technology Development[Suggestions of Strategic Plan 2017]1.

The technology development plan shall be formulated based on the following understanding about the fuel debris retrieval
project: it is a comprehensive program encompassing preparatory work, waste removal, treatment and storage, and postremoval work. It requires total optimization through careful considerations, including coordination with other work conductedon site.

2.

Fuel debris retrieval methods with high potential shall be selected first as primary development program targets. Then, theprogram shall be carried out by a step-by-step approach with flexibility to reflect information obtained during the program’s
progress.

3.

The development program shall be carried out on the premise that a combination of various methods will be needed toretrieve fuel debris successfully.

4.

The focus will be on the partial submersion method when conducting preliminary engineering and R&D activities.

5.

Methods to retrieve fuel debris that accumulated in the PCV bottom shall be given top priority. Then, the development
program shall be reviewed regularly based on knowledge and experiences obtained from these activities.

6.

The method to access inside PCV laterally (side-entry method) shall be studied first as a route to access fuel debris at thePCV bottom. The points to note in construction using this method are as follows:•

Reducing the radiation dose at the work site•

Establishing water level control technology•

Establishing cell connection technology and securing areas⚫

Study and development will be conducted by focusing on technologies required to retrieve fuel debris at the PCV bottom by "Partial
submersion-the side entry method."
Study and development of common technologies by methods that are not dependent on collection/cutting and dust collection technologies
will also be conducted by focusing on technologies required to retrieve fuel debris at the PCV bottom by "Partial submersion-the side entry
method".
(Example: Collection of fuel debris in particle or powder form, MCCI debris processing)The development program shall be designed with consideration to relevant information, including those obtained by investigating inside thePCV. The various methodological choices will be prepared with contingencies in case a single technology and method is insufficient, andflexible combinations of different technologies and methods are required.

⚫

⚫

©International Research Institute for Nuclear Decommissioning

No.8

3. Project Overview
3.2. Basic Policy of Fundamental Technology Development
Based on the policies listed in the previous sections, implementation policies for each development item aredetermined as follows:
Publicly offered development items

Implementation policy

Reference

1) Technical development to prevent fueldebris diffusion[1] Development of a fuel debris collection
systemWhile retrieval technologies are applicable to different types of work in common, study
and development shall focus on technologies applicable to retrieving fuel debris at thePCV bottom (including fuel debris fragments generated by cutting) using a the side
entry method, which is likely to be used for the actual retrieval project.

Slide No.12[2] Development of a fuel debris cutting/dustcollection system

While cutting and dust collection technologies are applicable to different types of workin common, study and development shall focus on technologies applicable to cutting
and collecting fuel debris in the PCV bottom using a the side entry method.

Slide No.
37

[3] Development of methods to prevent fueldebris diffusion

The diffusion of fuel debris from the PCV bottom to vent pipes and the S/C may occur
during fuel debris retrieval. Technologies to prevent such diffusion shall be studied anddeveloped.

Slide No.53

2) Element technology development for
installing retrieval equipment[1] Element technology development related
to work cellTechnologies to connect cells and PCV without leaking radioactive materials shall be
studied especially closely and developed, including alternate methods to achieve thesafe confinement of such materials. In addition, technologies for transporting andinstalling cells and the estimate of the cells’ impact on the reactor building (R/B) shallalso be studied and developed; the former is related to worker exposure and the latteris related to ensuring safety in an emergency.

Slide No.61[2] Technical development for removing
interfering objects during fuel debris
retrievalStudy and develop methods for removing interfering objects that block access to fueldebris in the PCV bottom by a the side entry method.
Methods and technologies applicable to the dismantlement of interfering objects
through top entry shall be studied first. Then, further development shall be implemented
on those that are found essential and difficult to be embodied.

Slide No.94

First, the basic remote maintenance approach shall be based on internal cell facilities
for a the side entry method. Then, the plan of study and development of maintenanceequipment shall be formulated.

Slide
No.174

3) Development of remote maintenancetechnologies for fuel debris retrieval
equipment©International Research Institute for Nuclear Decommissioning

No.9

4. Project Schedule
Schedule for Upgrading of Fundamental Technology for Retrieval of Fuel Debris and Internal Structures
Category
1. Technicaldevelopment for
prevention of fueldebris diffusion(i)Development offuel debris
retrieval system(ii)Development offuel debris cutting
and dust collection
system

FY 2017
FY 2018
Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar

Subcategory
a. Conceptual Studyb. Study the specific fueldebris retrieval proposalc. Organization of study
results
d. Summarya. Conceptual Study/Test
Planb. Test preparation/test
device test production
c. Element Test

Conceptual Study
Study for specific proposal forfuel debris collection

Notes(latest status)

Organization of study results
Summary

Conceptual study/test plan
Preparation for tests/test
device test production

Element Test
Summaryd. Summary
2. Element technology
a. Conceptual
development forStudy/Test Planremoval equipmentb. Test preparation/test
installation
device test
production(i)Element technology
development related to c. Element Test
work celld. Summarya. Conceptual Study/Test(ii)Technical developmentPlanfor removingb.
Test preparation/testinterfering objects
device test production
during fuel debrisc. Element Test
retrieval
3. Development of
remote maintenancetechnologies for fueldebris retrieval
equipment

Conceptual study/test plan
Preparation for tests/test device
prototyping

Element Test
Summary
Conceptual study/test plan
Preparation for tests/test
device prototyping
Element Test

Summaryd. Summary
Conceptual Studya. Conceptual Studyb. Study of specificmaintenance/layout
proposalc. Development planning

LegendStudy of specific maintenance/layout proposal
Development planning
Summaryd. SummaryPlan:
Possibility of earlier start:
Actual Schedule :Grant
DecisionLine linking connected
items:Key milestones

Interim report

Annual report

Interim report

Submission ofdevelopment
achievement report©International Research Institute for Nuclear Decommissioning5. Subsidized Project Scope

No.10[Purpose]
For FY2017-2018, the program will be implemented with focus on design study and element tests basedon the fuel debris retrieval policy announced in September 2017 and with consideration of the policy’s
applicability; the program will be implemented with a view to developing the equipment to be used in theactual debris removal work so that the work will enter a practical phase.

[Main scope of this project]
1) Technical development for prevention of fuel debris diffusion
Effective, flexible collection technologies applicable to different fuel debris conditions, and technologies tocollect dust generated during the removal work, will be developed to prevent diffusion of dust and othermaterials produced during fuel debris retrieval.
2) Element technology development for installing retrieval equipment
Develop remote technologies for each task that are assumed during fuel debris retrieval because the site ishighly radioactive, so many of the tasks must be controlled remotely.
3) Development of remote maintenance technologies for fuel debris retrieval equipment
Fuel debris retrieval equipment/devices and systems (including the fuel debris cutting and dust collecting
systems, containers and work tables, monitoring system, and robot arms to manipulate the equipment) need
to be maintained remotely as a rule by because they are installed in a highly radioactive area. This requires
reviewing maintenance methods for fuel debris retrieval equipment and systems, evaluating feasibility,
identifying issues, and studying a reasonable action policy with actual equipment.

©International Research Institute for Nuclear DecommissioningNo.11

6. Implementation Details
6.1 Development Plan

Project development plan is shown in the figure below. Detailed implementation items are listed on the next and subsequent pages.

Methods for removing interfering objects
by fuel debris retrieval equipment using theside entry method
Technical development for removing
interfering objects and the RPV bottom part

Work cell sealing method (inflate sealing)

Boring through thebiological shielding wall

Preventing contamination spreading to the suppression
chamber

Verifying maneuverability by a
combination of a robot arm andaccess rail

Processing method to minimize fuel debris
diffusion©International Research Institute for Nuclear DecommissioningNo.12

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system[2] Development of a fuel debris cutting/dust collection system[3] Development of methods to prevent fuel debris diffusion

2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell[2] Technical development for removing interfering objects during fuel debris retrieval

3) Development of remote maintenance technologies for fuel debris retrieval equipment©International Research Institute for Nuclear DecommissioningNo.13

6. Implementation Details
6.2. Implementation Details

1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system
Fuel debris is assumed to have accumulated in the primary containment vessel (PCV) in various
forms (such as rubble, polluted sludge, and fine powder). Therefore, development of the system will
provide effective retrieval methods and systems to handle different debris forms. The transportation andtemporary storage system to send removed fuel debris to canisters and other containers needs to be
developed in this theme as well.
Specifically, the following methods and technologies need to be studied to prepare a suitable fueldebris retrieval method and system. Additionally, issues need to be identified and addressed by
performing element tests when necessary.
a. Means and methods of collecting fuel debris (such as suction and grabbing)• Information on fuel debris distribution and characteristics are under review.
• Details of suction and grabbing methods are under consideration, based on the information
obtained from the above-mentioned work.

b. Method to store fuel debris in unit can• Identify the specific method for packing fuel debris in unit cans based on results of studies listed
in Paragraph a.
c. Fluid control method for fuel debris (such as dewatering or desiccation)• Methods of controlling the fluid of the fuel debris may be accompanied by hydrogen generation.
The relationship between the control methods and hydrogen generation is being studied.
d. Method to store unit cans in canister and to transfer them
• A unit can will be designed as a cylindrical can of ⌀200 mm in principle.

©International Research Institute for Nuclear Decommissioning6. Implementation Details

No.14

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system⚫ Purpose of development➢ Fuel debris is assumed to have accumulated in the primary containment vessel (PCV) in various
forms (such as lump, granular, and powder). Therefore, development of the system will provide
effective collection methods and systems to handle different debris forms.
⚫ Issues to be resolved➢ Find specific fuel debris properties and volumes (ratio of lumps, powder and power debris)➢ Clarification of powdery debris suction and collection method⚫ Development approach➢ Presumption of total fuel debris amount to be removed✓ Estimation of fuel debris properties, distribution and processing methods✓ Estimation of fuel debris properties and amount after processing➢ Clarification of retrieval processes such as grabbing and suction✓ Survey of, and benchmark for, collection equipment✓ Trade-off of collection systems➢ Study of interface conditions with the plant operation systems and infrastructure➢ Study of system for collecting and transferring to canister⚫ Expected results➢ Feasibility of fuel debris collection work
➢ Specifications of particle-shaped fuel debris retrieval system➢ Fuel debris collection rate (throughput)©International Research Institute for Nuclear DecommissioningNo.15

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)○ Information on fuel debris distribution and characteristics in Unit 1 are under review to find specific fuel debris properties and volume.
No.

Position of
distribution

Mass [t]Characteristics

RPV insulationmaterial

RPV head

Steam dryer
RPV bottom
part

Shroud head

3

RPV
core
RPV
bottom part

CRD/instru
mentation
guide tube

Molten core materials are rapidly cooled down
into small pieces

A few μm a few cm(U,Zr)O2(Zr,U)O2

Powdery,
Grained

Most of the debris in this area
consists of crust

Molten core materials are rapidly cooled down
into small pieces

A few μm a few cm(U,Zr)O2(Zr,U)O2

Crust contains Zr alloy and
ZrB and partially rigid andtoughSlowly cooled to form lumps

Lumps form

Thickness
A few
dozen cm

(U,Zr)O2(Zr,U)O2

Thickness
0.1-1 m(U,Zr)O2, (Zr,U)O2
Zr(O),Fe

Penetratio
n depth
10 and a
few cm(U,Zr)O2,(Zr,U)O2, SUS

Structure andadhered debris

MCCI/powdery
Grained

CRD instrumentation
guide tube
MCCI
Crust

Outside thepedestal

7-20

Debris adhered in gaps
inside and on the outersurface of tubes

Debris clogged the flow passage of lower SUS
tubes from the bottom end of the pressure vessel

The debris forms multiple
layers; most are likely toconsist of MCCI debris lumps

Molten reactor core materials leaked out of RPV,
dispersed, and quenched
Crust fractured during MCCI and broken into
small fragments due to ejection of molten corium

50 μm 20cm

(U,Zr)O2, (U,Zr)SiO2

Ejected materials containing metal components
adhere to the wall surface. Debris on the floor
has a hollow structure, and the crust in the upper
part is porous, with fewer metal components.

Thickness
0.1-1 m(U,Zr)O2,(U,Zr)SiO2,SiO2

A few
dozen cmor more(U,Zr)O2,(U,Zr)SiO2,SiO2

Large amounts of brittle
debris with high porosity
accumulated

120-209MCCI in lumpformUpper part consists of rigid corium with highporosity
Lower part is rigid with a low porosity
Metallic balls are in the central area and near thewall

Metal layer

Debris distributed relatively uniformly in thebottom of the MCCI

Under
study

Fe, FeSiO2
Fe-Zr

Grainy debris has leaked from the pedestal

50 μm 20cm

(U,Zr)O2, (U,Zr)SiO2

MCCI/powdery
GrainedOutsidePedestal

0-3

Debris formed by mixed and solidified molten
metals and oxide fuelInsidePedestal

5

Fuel: UO2
Cladding: Zry-2

Adhered to or stacked onresidual structures

4

Inside the pedestal

4 m or lessPowdery,
GrainedCrust(bedrock)

Upper grid plate

Composition

Some fuel assemblies remain without meltingdown

RPV core2

Size

All fuel assemblies may havemelted down, but some could
remainFuel rod stubs

Shield plug

Debris properties

Features
MAAP

1

PCV head

General state

MCCI
Crust/lump
MCCI debris

The layer separation inside
the pedestal is unclear; there
is a crust and MCCI in a
lumpy form.

Corium leaked from the pedestal reacted withthe concrete and solidified
Slightly rich in metal component

70-153(U,Zr)O2,(U,Zr)SiO2,SiO2
FeSiO2©International Research Institute for Nuclear Decommissioning
0.5 m orless

6. Implementation Details

No.16

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)○ Data on fuel debris distribution and properties in Unit 2 are under review to identify specific fuel debris properties andvolumes.
Mass [t]Debris propertiesNo.

PCV head

Shield plug

Characterist
ics

1
Fuel rodstubs

RPV insulationmaterial

RPV head

Position of
distribution

General state

MAAP
Fuel assemblies remain in thereactor core periphery

RPV core

Steam dryer

Powdery,
GrainedFeatures

Upper fuel assemblies in the reactor core
periphery have melted down, and a few fuelpellets remain there
The molten material is 25% metalcomponents

Powdery,
GrainedUpper grid plate
RPV bottom
part

RPV
core

Lumps form

3

CRD instrumentation
guide tube

CRD/instru
mentation
guide tube

4

PipingPowdery,
GrainedInside the pedestal
InsidePedestal

Lumps form

5

Powdery,
GrainedOutsidePedestal

Outside thepedestal

4 m orless

UO2, ZrO2,(U,Zr)O2, Zr(O)Adhered to or stacked onresidual structures

Molten core materials are rapidly cooled
down into small pieces

A few μm a few cm

Debris exists in the center of the
RPV bottom.
The main component of thedebris is estimated to be UO2(Some debris forms a pellet)
Some CRGT remained without
melting

Molten core materials are rapidly cooled
down into small pieces

A few μm a few cm

Slowly cooled to form lumps

Thickness
A few
dozen cm

(U,Zr)O2(Zr,U)O2

Thickness
0.1-1 m(U,Zr)O2,(Zr,U)O2
Zr(O),Fe(U,Zr)O2,(Zr,U)O2, SUS

Debris formed by mixed and solidified
molten metals and oxide fuelCrust(bedrock)

RPV bottom
part

Composition

0-51

Shroud head
2

Size

25-85

Debris adhered in gaps insideand on the outer surface oftubes

Debris clogged the flow passage of lower
SUS tubes from the bottom end of thepressure vessel

Penetratio
n depth
10 and a
few cmBecause of early water injection,
most of the molten debris
solidified without forming MCCI

Molten reactor core materials leaked out of
RPV, dispersed, and quenched
Shows little reaction with concrete

50 μm 20cm

There may be MCCI is in thesump pit

Solidified debris in lump form is distributed
uniformly
There may be MCCI in the sump pit

Solidified debris leaked from thepedestal
Most is powdery or grainy

Grainy debris has leaked from the pedestal(U,Zr)O2(Zr,U)O2(U,Zr)O2(Zr,U)O2

UO2, Zr(O)(U,Zr)O2, Fe

102-223
Thickness
15 cm

UO2, Zr(O)(U,Zr)O2, Fe(U,Zr)SiO2

50 μm 20cm

UO2, Zr(O)(U,Zr)O2, Fe

Penetratio
n depth0.25m orless

UO2, Zr(O)(U,Zr)O2, Fe(U,Zr)SiO2

3-142
Lumps form

Corium leaked from the pedestal reactedwith the concrete and solidified
Slightly rich in metal component©International Research Institute for Nuclear Decommissioning6. Implementation Details

No.17

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)○ Information on fuel debris distribution and characteristics in Unit 3 are under review to identify specific fuel debris properties andvolume.
Mass [t]Debris properties
No.

Position of
distribution

Characterist
ics

General state

Features

Fuel rodstubs

Almost all the fuel melted down,
and some undamaged fuelassemblies remain in the reactor
core periphery. (MAAP)

The top part of fuel assemblies in thereactor core periphery melted down, and a
few fuel pellets remain there

Adhered to or stacked onresidual structures

Molten core materials are rapidly cooled
down into small pieces

A few μm a few cm

Both the MAAP and the
SAMPSON code indicate small
amounts of debris in the lower
plenumMolten core materials are rapidly cooled
down into small pieces

A few μm a few cm

Slowly cooled to form lumps

Thickness
A few
dozen cm

(U,Zr)O2(Zr,U)O2

Thickness
0.1-1 m(U,Zr)O2,(Zr,U)O2
Zr(O),Fe

Penetratio
n depth
10 and a
few cm(U,Zr)O2,(Zr,U)O2, SUS

MAAP

Size

Composition

4 m orless

UO2, ZrO2,(U,Zr)O2, Zr(O)PCV head1

Shield plug
RPV insulationmaterial

RPV head

RPV core
Powdery,
GrainedSteam dryer
Shroud head2

Powdery,
GrainedUpper grid plate
RPV bottom
part

RPV
core
RPV bottom
part

Lumps form

Debris formed by mixed and solidified
molten metals and oxide fuelCrust(bedrock)3

CRD instrumentation
guide tube

CRD/instru
mentation
guide tube

Piping4
Powdery,
GrainedInside the pedestal
InsidePedestal

Debris adhered in gaps insideand on the outer surface oftubes

Debris clogged the flow passage of thelower SUS tubes from the top end of thepressure vessel

Because of early water injection,
most of the molten debris
solidified without forming MCCI
There may be MCCI is in thesump pit

Molten reactor core materials leaked out of
RPV, dispersed, and quenched
Shows little reaction with concrete

Outside thepedestal

Powdery,
GrainedOutsidePedestal
Lumps form

21-79

A few μm a few cm

Solidified debris leaked from thepedestal
Most is powdery or grainy(U,Zr)O2(Zr,U)O2(U,Zr)O2(Zr,U)O2

UO2, Zr(O)(U,Zr)O2, Fe

92-277
Solidified debris in lump form is distributed
uniformly
There may be MCCI in the sump pit

Lumps form

5

0-31

Thickness
15 cm
50 μm 20cm

Grainy debris has leaked from the pedestal

Corium leaked from the pedestal reactedwith the concrete and solidified
Slightly rich in metal component

0-146

Penetratio
n depth
0.20 m or
less

UO2, Zr(O)(U,Zr)O2, Fe(U,Zr)SiO2
UO2, Zr(O)(U,Zr)O2, Fe
UO2, Zr(O)(U,Zr)O2, Fe(U,Zr)SiO2©International Research Institute for Nuclear DecommissioningNo.18

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)○ Clarification of preconditions to achieving the suction of debris
During pre-staging, before starting detailed studies of a suction and collection system for powder
and particle debris, the preconditions for debris suction were set as follows:[1] Diameter of collected debris⌀0.1-⌀10 mm[2] Specific gravity of sucked debrisSpecific gravity: 2-11
[3] Debris suction velocity
2 m/sec[4] Debris suction lift
Approx. 5 m: Unit2 is assumed on the maintenance side[5] System installation place
Considering footprint, equipment exchange, and maintainability

Direct suction on bottom surface

Suction of debris with water

Image

SuctionEquipment
Solid liquid
separator

Solid liquid
separator

SuctionEquipment

DebrisApplicability/
Remarks[A]• Minimum footprint on robot arm• The maximum load capacity of robot arms
won’t be affected by the suction head

Somewhat
Applicable

Debris• Difficulty in carrying the pump in PCV(Difficulty in repair work in case of failure)• The maximum load capacity of robot arms may need to
be increased©International Research Institute for Nuclear DecommissioningNo.19

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)○ Study on method of collecting debris by suction
During pre-staging, before starting detailed studies of a suction and collection system for
powder and particle debris, technology mapping was performed on applicable equipment(such as filter systems and pumps).
The filter technology mapping is performed with focus on:[1] Separation method using difference in specific gravity[2] Separation method using difference in particle size
[3] Separation method using chemical properties, and other methods

As with the filter, the following types of pumps are focused on individually in thetechnology mapping of the pump:[1] Non-positive-displacement pumps (turbine type)[2] Positive-displacement pumps[3] Other pumps©International Research Institute for Nuclear Decommissioning6. Implementation Details

No.20

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)
Filter technology mapping: [1] Gravity filtration
Type

Principles andFeatures

Sedimentation separator

Liquid Cyclone

A type of separator that allows particles to settle out
due to differences in specific gravity between particles
and liquid in the tank containing stagnant water anddischarges supernatant liquid as processed water.
The tank may have an additional structure in it toincrease separation efficiency. The advantage of thistype is its wide range of applicable particle sizes. A
flocculating agent is often added to facilitate particle
sedimentation.

A type of separator that causes swirl flow of fluidthat flows in it so that particles in the fluid areseparated by centrifugal force.
It has a simple structure.
The separation efficiency is higher with large
specific gravity.

Centrifugal separator (spin-dryer)
A type of separator that turns a rotor at a highspeed so that particles contained in the liquid
are separated from the liquid by centrifugal
force.
The structure, such as the mechanism todischarge particles, tends to be complex.

Outlet

Raw
water

Inlet

Schematic
Drawing
Vortextube

This method is widely used to treat drinking water,
sewage, and general industrial wastewater to separate
SS (suspended solids).

This method is used to treat general industrial
wastewater and is now being used to treat sewage (asan alternative for the primary sedimentation tank).

Applicability/
Remarks[A]

Secondary wastes increase because of theflocculating agent.
Low maintainability due to many drives.

High maintainability with less drives

Used in production facilities for solid-liquid separation.

Structure is complex with many moving parts.
Low maintainability.

Not
Applicable

Major application

Somew
hat
Applicable

Extraction©International Research Institute for Nuclear Decommissioning6. Implementation Details

No.21

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)
Filter technology mapping: [2] Particle size filtration
Auto strainer

MF/UF membrane filtration

RO membrane filtration

Principles andFeatures

Raw water is run through a tank filled with filler
material, and the filler material mesh captures
particles contained in the raw water. The
captured particles are detached from the filler
material and collected by backwashing.
High pressure water filters are also included inthis type.
The equipment is called Sand Filtration Tower if
the filler is sand or anthracite, or it is called theMedia Filter if the filler is polymer material.

Swirl flow is caused in a tank with an
installed screen, and the particles arefiltered when the cross flow caused by theswirl passes through the screen.
The swirl flow washes the surface of thescreen and prevents it from clogging.
The particle sizes to be filtered can bechanged by changing the mesh size of thescreen.

Raw water is run through a porous
membrane in one direction, and water thatpasses through the membrane iscollected. Particles larger than the size ofthe aperture are blocked and filtered by
the membrane.
An organic and inorganic membrane areused.

Pressurized, raw water is run though awater-permeable membrane in one
direction so that only water molecules canpass to the other side of the membrane.
Thus, filtered water is collected. Dissolved
molecules can be separated.

High-pressure
cylinder case

Raw
water
Conce
ntrated
Water

Sand filter/media filter

O-ring

Filtrate

Hollow
fiber layer

Drain(sludge detection)

Contrary to fewer drives,secondary wastes increase due
to media exchange.

It is used in the seawater intake system at
power plants.
It is a proven application for a 1F stagnant
water treatment system.
[A]

High maintainability with fewer
drives.

RO membrane plant

A filtering system with an organic membrane isused to treat general industrial wastewater andpower plant wastewater.
Inorganic membranes are applied to 1F (ALPS).

This system is widely used as a seawater
desalination system.
Applied to cooling water desalination
system on 1F.

This system has fewer moving
parts, and it can capture fineparticles.
The inorganic membraneprovides radiation resistance.

This system has fewer moving parts,
and it can capture fine particles(including ions). Particle filtration
does not require this level of
performance.
If an organic membrane is used,radiation resistance may beinsufficient.

Somewhat
Applicable

Applicability/
Remarks

Somewhat
Applicable

Major
application

The sand filtration tower is widely used totreat drinking water, sewage, and generalindustrial wastewater to separate SS (oflow concentration).

End
plate

Fresh
water

Water
outletNot Applicable

Schematic
DrawingO-ringMounting plate

Water
inlet

Water
collection tank

End plate

Type©International Research Institute for Nuclear DecommissioningNo.22

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)
Filter technology mapping: [3] Chemical filtration
Type

Principles andFeatures

Adsorption Vessel

Electrodialysis

Evaporative concentration apparatus

Raw water is run through a tower filled with adsorbent so that
contents dissolved in the raw water, such as molecules andions, are adsorbed and removed by chemical andelectrochemical actions.
Different types of adsorbents including, the following, are used
depending on the process purpose: activated carbon (fororganic materials), ion-exchange resin (for cation and anion),chelating resin (for heavy metals), zeolite (for cesium, etc.),
and tannic acid.

Two electrodes are disposed on the both ends of a setof ion-exchange membranes inside the equipment.
Voltage is applied to the electrodes so that raw waterions are moved, separated and concentrated.

Raw water is vaporized so that it is separated into clean
distilled water and concentrated raw water.
Atmospheric or vacuum vaporization methods may be
used.

Processed water(pure water)

Concentrated
Water

Schematic
Drawing

Feed water(RO water)
Schematic illustration ofconcentration apparatus

Not suitable for particle filtration If material
is soluble into ions, this method isapplicable.
Better maintainability because of lessdrives.
Secondary wastes increase because theadsorbent needs to be exchanged
periodically.

The structure is complex. In addition, theresistance to radiation may be insufficientbecause the dialysis membrane(separation membrane) is made oforganic resin.

This method is used for liquid waste treatment at nuclear
power stations (including 1F of this station).

Not ApplicableThis method is used for the removal of acid and alkali
from waste liquid.

Not Applicable

Applicability/
Remarks

There are many application cases for feed water andwastewater treatment.

Not Applicable

Major application

The evaporative concentration apparatus isprovided primarily to separate soluble materials(separation into concentrated raw water anddistilled water). This method is unsuitable forremoving particles because they accumulate as
sludge and reduce heat-transfer performance.
If particles are water soluble, this method isapplicable.

©International Research Institute for Nuclear Decommissioning6. Implementation Details

No.23

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)
Filter technology mapping : [4] Summary
After applying the results of the studies above to the size of debris to be removed, the following guidelines are
obtained:○ If a method using specific gravity differences is chosen, the cyclone-type solid-liquid separation method seems
advantageous for particle filtration because of its high maintainability and high radiation resistance. For a method
using particle sizes, the auto strainer appears promising.
○ None of methods studied in the section of "Use of chemical properties and other principles" is suitable forremoving particles.
○ The auto strainer can be categorized in the same group as the cyclone-type solid-liquid separator because it uses
swirl flow. In debris collection, a liquid cyclone separator should be studied.
Preconditioned range of the diameters ofTable Relation matrix between dust particle diameter and applicable removal technology
1nm
(i)

100nm

10µm

particles to be collected
1mm

Sedimentation separator
Liquid Cyclone
Centrifugal separator (spindryer)(ii)

Sand filter/media filter
Auto strainer
MF membrane
UF membrane
RO separation membrane(iii)

Adsorption Vessel
Electrodialysis
Evaporative concentration
apparatus©International Research Institute for Nuclear DecommissioningNo.24

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)Technology mapping for pumps: [1] Non-positive-displacement pump (turbine type)
Canned motor pump

Magnet pump

Axial-flow pump

A type of non-positive-displacement
pumps (turbo pumps).
Fluid flows because the centrifugal
force increases the pressure thatthe impeller rotation produces in thefluid.
This is the most popularly
manufactured pump.

A type of non-positive-displacement
pumps (turbo pumps).
An impeller and a rotor are
packaged together in a single
housing, like being canned (thename comes from this) so that it caneliminate leakage.

A type of non-positive-displacement
pumps (turbo pumps).
An impeller and a shaft with driven
magnets are put together in a single
container, and driving magnets rotate tocause the driven magnets to rotate, sothat the impeller also rotates.
Like canned motor pumps, no leakage is
expected.

A type of non-positive-displacement
pumps (turbo pumps).
A type of pump that has an impeller issimilar to a ship propeller in shape androtates the impeller to produce thrust in
fluid so that the fluid flows in the axial
direction. This type of pump is often used
for low-lift and high volume pumping
compared to centrifugal (turbine) pumps.

Impeller

Discharge outlet

Pump casing

Frame

Schematic
Drawing

Motor

Suctionport

Different models with a varietyof specifications are produced
for this type of pump,including those used to moveearth and sand in dredge
work because of their highability to convey irregular solid
contents (of ⌀10 mm or larger)
contained in fluid

Cannedmotor stator

Because of the leakage elimination
feature, this type of pump is used in fluid
conveyance systems where fluid leakage
must be prevented, such as in chemicalplant systems.
It can be designed to handle highpressure fluid compared to a magnet
pump.

Somewhat ApplicableThis type of pump is widely used ina variety of applications, including
conveying drinking water andsewage and as process pumps forchemical plants.

[A]

Applicability/
Remarks

Motor shaft

Bearing

Impeller

Major application

Impeller
Driven magnet(s)(permanent magnet)

Cannedmotor stator

Low ability to convey
irregular solid contents (⌀2mm or so)Driving magnets

Because of the leakage elimination
feature, this type of pump is used in
fluid conveyance systems where
fluid leakage must be prevented,
such as in chemical plant systems.

This type of pump is often used forriver drainage and agricultural
irrigation systems because of its
high-volume pumping capacity.

Fluid pressure cannot be
increased much compared
to a canned motor pumpThis type of pump does
not meet the debris
retrieval system’s highpump head and highpumping capacity
requirement

Not ApplicablePrinciples andFeatures

Centrifugal pump

Not Applicable

Type©International Research Institute for Nuclear DecommissioningNo.25

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)Technology mapping for pumps: [1] Non-positive-displacement pump (turbine type)
Submersible pump

PAAC pump

A type of non-positive-displacement pumps (turbo
pumps).
A pump driven by hydraulic pressure. It is designed
for use in special conditions where a certain
restriction exists, such as no electric power.
This type of pump is submerged in the fluid to bepumped.

A type of non-positive-displacement pumps (turbo pumps).

This type of pump is used in food processing
machines and explosion-proof environments.

This type of pump is for underwater operations in water
treatment facilities, construction sites, and commercial
facilities as well as households.
This pump is advantageous in that it requires no installation
space and its operation noise is lower because it operates
underwater.

Somew
hat
Applicable

Principles and Features

Hydro-turbo pump

Somew
hat
Applicable

Type

The submergible pump is a generic term for pumps equippedwith waterproof motors and parts for underwater use.
A centrifugal pump is used mostly.
Some models are used for pumping sewage (agricultural
wastewater and rain water) and water discharge atconstruction sites; some models can transfer irregular solid
objects such as gravel in fluid.

A type of non-positive-displacement pumps (turbo pumps).
While this type of pump does not adopt any notableprinciple, the integrated design of an impeller, shaft andsupporting structure (MSU: mobile sub-unit) inside thecasing is one of features making this assembly
exchangeable from the motor side.
In addition, there is an option that offers ability to
exchange the assembly remotely.

Schematic Drawing

Applicability/Remarks• Low ability to convey irregular solid contents (⌀6mm)•Difficulty in carrying the pump in RPV

Difficulty in carrying the pump in RPV

NotApplicable

Major application

This type of pump is designed to convey
radioactive fluid. It is used in reprocessing
facilities.

•Low ability to convey irregular solid contents(⌀0.3 mm)
•Difficulty in carrying the pump in RPV©International Research Institute for Nuclear Decommissioning6. Implementation Details

No.26

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)Technology mapping for pumps: [2] Positive-displacement pumpType

Diaphragm pumpGear pump

One of positive-displacement pumps.
This type of pump conveys fluid byexerting pressure on the fluid to change
the volume caused by the reciprocating
movement of the piston.

One of positive-displacement pumps.
This type of pump conveys fluid byexerting pressure on the fluid bychanging in the volume of thediaphragm.

One of positive-displacement pumps.
Gears that have design similar to an
impeller rotate and engage to convey
fluid.

Seal line(packing)
Priming water

One of positive-displacement pumps
Fluid is conveyed by the force causedby changing the volume of gap (cavity)
between the cylindrical casing (stator)
and the spiral shaft (rotor). Such achange in the cavity volume is causedby the rotation of the rotor.

Rotor

Valve

High-pressure pumping is notwhat the fuel debris retrieval
system demands.

Proven application in TMI.
This type of pump has a self-suction
capability and doesn’t cause a problem
in case of empty load operation. It canconvey high viscosity fluids. It is often
used for industrial, chemical, andsanitary applications.
The self-suction capability of thispump is 4 m and short of 5 m.

This type of pump is suitable forconveying high viscosity fluids (such asoils) and often used in a hydraulicsystem.

Low ability to convey irregularsolid contents

This type of pump is often used for
applications where high viscosity fluids
are mainly handled, such as foodmaterials (bean paste, syrup),chemicals (emulsion, solvents),
environmental materials (polluted mud,powder activated carbon slurry), andpaper-making materials (pulp).
Not
Applicable

This type of pump is often used for
applications where high pressure
pumping is required because its
discharge pressure can be set high.

Stator

Not
Applicable

Applicability/
Remarks

Valve

Diaphragm(membrane)

Mohno pump(screw pump)

Lower
valve

Not
Applicable

Major application

Pistonvalve

Schematic
Drawing

Suctionprocess

Somew
hat
Applicable

Principles andFeatures

Piston pump

Low ability to convey irregularsolid contents©International Research Institute for Nuclear DecommissioningNo.27

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)
Pump technology mapping: [3] Other pumps
Type

Ejector/vacuum pump

Airlift pump

Siphon method

Principles andFeaturesThis type of pump is categorized in a special pump group.
It has a driving fluid inlet port, a driven fluid inlet port, and adischarge port. The driving fluid injected from its inlet port causes
negative pressure, so the driven fluid is aspirated through its inlet
port. Both the injected driving fluid and the aspirated driven fluid
are expelled from the discharge port together. In such a way, thedriven fluid is conveyed.
This kind of pump has a low failure rate because it has no active
component, but its energy efficiency is lower than othermechanical pumps.

This type of pump is categorized in a special pump group.
Compressed air is injected into a tube disposed in a fluid verticallynear its bottom end so that difference in specific gravity occurs in thefluid between the inside and outside of the tube. Air bubbles occur
and rise along the tube; the rising bubbles cause the fluid to besucked from the opening of the tube at the bottom end. This type has
low failure rate because of no active component but a low pump headbecause of driving force relying on only rising bubbles.

It may not be accurate to call this method a pump.
This method relies on the principle that a fluid flows from thestart point to the end point continuously, without pumping, aslong as the start point is higher than the end point. This
principle applies even if a passage connecting the two points
runs through an even higher position than the start point,provided the passage is made of a tube with no hole, and thetube is filled with the fluid all the time.

Schematic
Drawing

DiffuserNozzleSteam (*)

Compressedair (P)Air

Bed
Workpiece

Major
application
Applicability/Remarks

VacuumThis type of pump is often used for applications where vacuum isrequired, such as deairing, defoaming, and distilling.

Somewhat
Applicable• High maintainability with low
failure rate.
• Compact size and high ability tohandle irregular solid contents.

Proven application in TMI.
This type of pump is often used to convey removed soil at dredging
work sites, to pump hot well water, and so on.

Somewhat
Applicable･The fluid driving force may be insufficientsince the water depth at the concerned unit is
not as much as that at TMI.
･It will be difficult to install this type of pumpbecause 1F is narrow.

Waterworks

Not
Applicable･No restriction on acceptable irregular solid
contents.
･No active component･Large scale facility©International Research Institute for Nuclear DecommissioningNo.28

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing)
Pump technology mapping: [4] Summary○ In the non-positive-displacement pump (turbine type) category, a centrifugal pump seems advantageous because it can convey irregular solid
contents.
○ Although a diaphragm pump is promising in the positive-displacement pump category, its pump head does not meet the 5 m requirement set in thepreconditions.
○ The centrifugal pump type is selected as a primary candidate because it meets preconditions. Further study towards actual design will be
implemented based on this decision. As an alternative, application of other type, such as a submergible or vacuum pump, should also be studied.
Table - Debris Suction Pump Evaluation (showing [B] or higher ratings from technology mapping)

(i)

(ii)

(iii)

Acceptable size of
irregular solid
contents(⌀10 mm or more)

Suction pump
(5 m andhigher)Possibility tocarry in PCVCentrifugal pump

[A]

[A]

[A]
(Only hose)[A]

Canned motor pumpSomewhat
Applicable(⌀2 mm)[A][A](Only hose)[B] Applicable depending on debris diameter.

Hydro-turbo pumpSomewhat
Applicable(⌀6 mm)-Not Applicable[B] Applicable depending on debris diameter. Also applicable if the PCV can be
carried in.
However, difficulty anticipated in maintenance in the PCV.

Submersible pump[A]-

Somewhat
Applicable[B] Applicable if the PCV can be carried in. However, difficulty anticipated inmaintenance in the PCV.

Diaphragm pump[A]

Somewhat
Applicable
(4m)

[A]
(Only hose)[B] Applicable depending on suction pump. Pulsation requires attention.

[A]

[A]

Somewhat
Applicable[B] Applicable if the PCV can be carried in.

Ejector vacuum pump

Evaluation results

Required specifications of a pump set in the preconditions©International Research Institute for Nuclear DecommissioningNo.29

6. Implementation Details
6.2. Implementation Details

Robot tip
suction tool

1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system
Accumulated
powder debris
a. Means and methods of collecting fuel debris (such as suction and grabbing)○ Example of specific method of collecting powder debris by suction• A suction and collection system for powder debris, combined with each assumed
component, is under study for specification• The study scope will involve a mechanism to suck power-form debris in the PCV,
separate and collect powder debris, package the canister, and carry it out.
• Identify future issues from the assumed suction and collection system for powder debris.

Ordinary
water
supplyOutsideR/B

Conceptual drawing of a powderdebris retrieval system

Impeller

InsideR/B

Backwash water line
Feed
water
supplyContaminatedwater line

Pump seal water line

Debris suction pump(centrifugal pump)
OutletCrane

Cask carryingout cell

Debris removal
cell

Fuel debris
retrieval cell

Inlet
Double door system

Powdery debris

Trucktransport

Robot arm

Vortextube
Cask

Storage
Canister
Robot arm
Transferring carriage
Rail

Storage
Canister
Robot arm

Cycloneseparator
Fuel debris
collection can(Unit can)Inside PCV filling
water (Unit 2)

Extraction

Debris separator(cyclone-type separator)©International Research Institute for Nuclear DecommissioningNo.30

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systema. Means and methods of collecting fuel debris (such as suction and grabbing) Example clarifying the granular debris suction and collection method
Inside the PCVInside Pedestal
Fuel debris in particle or powder form/water

OutsidePedestal
Vent

Liquid waste

Vent

Exhausted inside the
PCV
Air

Air
Granular and powdery fuel debris(Collected by UC mesh)(Mesh structure)
Platform

1st
Positioning by a floor
trolley or the like

Suspending
and hoisting by
wire or cable
B1F

Schematic illustration ofchisel processing andsuctioning

Fuel debris
collection canLiquid waste
collection tankParticle and powder debris are collected with a
UC mesh. The mesh size depends on debris
particles/powders size distribution data, obtained
from debris cutting tests, as well as on a total
system design involving other equipment anddevices.

- Definitions by the Common Definition Working Group Lump debris: 10 mm or lessParticle debris: 0.1 mm ≦ and < 10 mm
Powder debris: < 0.1 mm

MCCI debris inside Pedestal at the bottom• Cutting MCCI debris by a chisel or the like

Only liquid
waste is sent
back to PCV

Vacuum pump
- Issues • Cutting and suctioning equipment installation
method(Feasibility investigation for the platform
construction)• UC placement and retrieval method(Is the lid opened/closed every time?)• Method to measure the amount of debris collected
in a UC(Using a level meter or monitoring camera?)• UC mesh size
(Exchange frequency to be confirmed)• maintenance method(Assembling relevant equipment as an integrated
unit and replace the unit periodically, for example)

Post-treatment water return• Sucking fragmented MCCI debris• Same method applied to MCCI debris
outside Pedestal

Fuel debris and water

Fuel debris that cannot be collected with suction andfiltration collection and remains in the liquid waste iscollected with liquid waste treatment equipment, which is
integrated in the total debris retrieval system.

©International Research Institute for Nuclear DecommissioningNo.31

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection systemb. Method to store fuel debris in unit can○ Study of methods of grabbing debris and collecting them into the unit can•Work procedures to grab cutout debris and put it in the unit, and amechanism, are under consideration.

•

Studying fuel debris processing methods, larger lump debris should
be grabbed, and smaller lump debris should be scooped.

•

Methods to control the appropriate amount of debris in the unit can
is also under consideration.

Robot arm

Fuel debris grabbing tool
Fuel Debris (example)
Unit Canister
Accessrail

Unit can transfer carriage

Grained debris

Crust
MCCI in lump form

Examples of debris collection tools

Powdery debris©International Research Institute for Nuclear DecommissioningNo.32

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system
c. Fluid control method for fuel debris (such as dewatering or desiccation)○ In the project for development of technology for collection, transfer and storage of fuel debris,the effects of residual fluid in fuel debris and in the canister are under in terms of sub-criticality,
prevention of hydrogen explosion caused by hydrogen generation accompanying radiolysis of
fluid (by reducing hydrogen generation), and corrosion control, etc.
○ The conceptual study of the fluid control system will be started after discussion andcoordination of fluid control method requirements.

©International Research Institute for Nuclear DecommissioningNo.33

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system
d. Method to store unit cans in canister and to transfer them
○ Assumed specifications of the unit can and the canister• In the early stage of fuel debris retrieval, a canister of ⌀210 mm is assumed to be used toprevent fuel debris criticality because the debris characteristics are not yet known.

• Accordingly, methods to collect and transfer debris are studied based on the use of the unit
can of ⌀ 210 mm first.
• In addition, the use of ⌀400 mm unit can is also considered based on the possibility that thesize may be adopted to increase the throughput of retrieval work if the possibility fuel debris
criticality is eliminated in the future.

©International Research Institute for Nuclear DecommissioningNo.34

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system
d. Method to store unit cans in canister and to transfer them
○ Handling of unit cans and canisters• Unit can:• Canister:• Cask:Handled in high-level contaminated areas.
Handled in mid-level contaminated areas.
Handled in low-level contaminated areas.

○ Issues for carrying-out of unit cans and canisters• Fuel debris contains nuclear materials. In the fuel debris retrieval project,a large amount of fuel debris needs to be handled must be transported
repeatedly for a long period. Therefore, it is essential to prevent the
spread of contaminants that may occur during the debris retrieval process
as much as possible (otherwise, contaminants accumulate and spread).
•

When the canister is brought in a highly contaminated area to put unitcans into it, there is a risk of contaminants attaching to the canister
surface.

•

Similarly, there is a risk of contaminating the cask surface when the cask
is brought in a mid-level contaminated area to put the canister in it.
Reactor
Building

If monitoring and decontaminating thesurface is not implemented, thecontamination level in the cells continuously
increases, which increases the radiationdose that workers receive during
maintenance work.

To move unit cans/canisters across contaminatedareas:••

The contamination level of each unit
can/canister’s surface must be measured toensure the outsides are not contaminated.
If the surface is contaminated, it must be
decontaminated to a permissible level.

Monitoring and decontamination of surface
contamination is very time-consuming workand reduces throughput significantly

Fuel debris carryingout building

Mini-Cask
System[4] Canister cell
Doubledoor
system

Double door
system[3] Caskcell

Storage
Canister

Double
Door
SystemHigh-level
Areas where fuel debris and wastes are handledcontaminated area: directly.

Storage
Canister[1] Fuel
debriscollection cellCask

Mid-level
Areas where fuel debris is contained in the canister andcontaminated area: handled indirectly. Or areas directly connected to a highlevel contaminated area.
Fuel debris is contained in a sealed container and
Low-level
contaminated area: handled indirectly.

©International Research Institute for Nuclear DecommissioningNo.35

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system
d. Method to store unit cans in canister and to transfer them
Methods to store unit cans in the canister and to transport the canister outside the reactor building arebeing studied with consideration of the following requirements:• The spread of contaminants that may occur in each step of the fuel retrieval process must be
minimized.
• Debris and debris containers must be transferred swiftly and efficiently to increase throughput.

Study example: Double door
By adopting a double door system, the following effects are expected:• The double-door system adopted to the canister and cask design eliminates the need to carrythose containers into a high-contamination area when packing unit cans in the canister and thecanister in the cask.
• Risk of contaminant spread is reduced since fuel debris is carried out in sealed containers.
• Throughput increases because surface contamination monitoring and decontamination work
can be decreased.
• The remote maintenance of the double door will be an issue.

Example of a double door
adopted to the canister

Example of a double door
adopted to the cask
©International Research Institute for Nuclear DecommissioningNo.36

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system
d. Method to store unit cans in canister and to transfer them➢Processes required for unit cans and canisters are listed above.
• Those processes include unit can transfer, criticality condition measurements, contamination levelmeasurements, unit can storage, and canister transfer➢

Identify specific transport equipment required for transporting unit cans
• The equipment includes cranes, transfer carriages, shielding doors, double doors, anddecontamination equipment➢

Identify a specific transport process for units can and canisters and deploy it in the installation layout➢

The process time will be calculated for each transport step of unit cans and canisters, and throughput
for the entire debris retrieval process will be calculated based on the each calculation result as a final
outcome• Improvement of throughput will also be studied• Comparison and study of effect of the use of ⌀400 unit can as well

©International Research Institute for Nuclear DecommissioningNo.37

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system[2] Development of a fuel debris cutting/dust collection system[3] Development of methods to prevent fuel debris diffusion
2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell[2] Technical development for removing interfering objects during fuel debris retrieval
3) Development of remote maintenance technologies for fuel debris retrieval equipment
4) R&D management©International Research Institute for Nuclear Decommissioning6. Implementation Details

No.38

6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection system
Cutting methods whose cutting performance data are available through cutting performance test results, including cutting testsof fuel debris simulant ceramics, metal-concrete mixtures, and contaminated structures, will be subjected to cutting
performance tests to obtain data, including the amount and particle size distribution of chips generated by those methods. In
addition, dust collection systems will be developed to match the cutting methods developed through the above-mentioned
activities, and dust collection efficiency data from the developed dust collection systems, with chips and dust generated bythese methods will be obtained by tests.
a. Listing of possibly effective processing and cutting methods with consideration of fuel debris characteristics andstudy of the listed methods• The review and study of processing and cutting methods that match different fuel debris characteristics is ongoing.
• Effective processing methods will be selected based on the study results.
b. Processing element tests with fuel debris simulant by effective processing/cutting methods• A processing elements test for chisel processing and ultrasonic core boring are planned.
c. Producing a test facility simulating fuel debris and contaminated structures used for processing tests• Specifications of simulated fuel debris and contaminated structures used in processing element tests are under study.
d. Study and analysis of dust collection systems used for chips and dust generated during cutting work
• The local dust collection system used to collect chips and dust produced in cutting and processing is under consideration
as a measure to prevent fuel debris diffusion.
• Methods to collect chips and dust generated during element tests for cutting methods, and to analyze the collected chips
and dust, will be coordinated from now.

©International Research Institute for Nuclear DecommissioningNo.39

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection system⚫ Purpose of development➢

To obtain data necessary to analyze the advantages and disadvantages of processing technologies applicable tofuel debris processing.
✓ Cutting performance (such as cutting speed) and the amounts of chips and dust produced✓ Development of a dust collection system⚫ Development approach➢➢➢➢

Conceptual study of potentially effective processing and cutting methods with consideration of fuel debris
characteristics
Selection of a MCCI test facility to be processed (for example, ceramics, metal-concrete mixtures, or contaminatedstructures)
Cutting performance tests (to obtain data, including the amount and particle size distribution of chips and dust
generated by cutting work)
Development of a dust collection system (including data collection concerning the efficiency of the system to collectthe chips and dust generated)⚫ Expected results➢➢➢➢

Determination of processing and cutting methods, each of which fit with different fuel debris characteristics.
Cutting performance data to estimate throughput.
Study result of local collection system (chips and dust spread prevention).
Analyzing results of particle size distribution in processing liquid waste.

©International Research Institute for Nuclear DecommissioningNo.40

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection system⚫ Issues to be resolved (essential factors in selecting fuel debris cutting technologies)

Task requirements

Safety Requirements*1

Requirements

Essential factors in the selection of fuel debris cutting technologies

Prevent abnormal generation of radioactive materials causedby nuclear reactions(There is no comparative data since every cutting method entails a risk)

Prevention of the emission of radioactive materials due toabnormal temperature rise in fuel debris

Input heat input to fuel debris shall be small.
(Especially, further assessment is required for thermal processing methods)

Prevention of abnormal diffusion of radioactive materials
caused by cutting fuel debris and structures

Fewer fumes (powders, fine particles, etc.) shall be emitted to the atmosphere.
Fewer chips and powders shall be emitted underwater.

The method must be capable of processing various types offuel debris, such as fuel assemblies, including fuel pellets andfuel claddings, reactor internals, pressure vessels, andconcrete

The method should not be affected by fuel debris characteristics, such as electric
conductivity (conductive or non-conductive), mechanical properties (such as hardness),
and thermal properties (melting point, boiling point)

The time required to retrieve fuel debris must be minimized
as much as possible

The processing speed must be high

The cutting tool head must reach fuel debris lying in narrowareas inside the RPV and PCV

The processing device (especial its head or tip) shall be small
Minimum demand of assist gas and other utilities

Little impact on the plant operation systems and infrastructureLess demand of water supply and less abrasive particles contained in AWJHigh feasibility of work area

Fewer utilities required and minimum scale of auxiliary facilities

Availability of technology

Technology can be currently available from a vendor.

*1: Requirements relevant only to fuel debris processing are excerpted from all safety requirements⚫
⚫

Promising processing methods are picked up based on essential selection factors, and element tests are performed for each method.
Then, the line of processing technologies must be prepared for equipment design and adopted depending on the accessibility of debris
locations.
©International Research Institute for Nuclear DecommissioningNo.41

6. Implementation Details
6.2. Implementation Details: methods that received good evaluation for

1) Technical development for prevention of fuel debris diffusion
fuel debris processing[2] Development of a fuel debris cutting/dust collection systema. Listing of possibly effective processing and cutting methods with consideration of fuel debris
characteristics and study of the listed methods
Applicable tovarious fuel debris

Processing
speed

Access ability(small head)

Heat input

Fume generation(aerial diffusion)

Amount of chips
generated(underwater diffusion)

Downsizing ofutilities

Availability

Core boring[A]

Somewhat
Applicable

[A]

[A]

[A]

Somewhat Applicable

[A]

[A]

[A] Finished

Disk saw[A][A]

Somewhat
Applicable

[A]

[A]

[A]

[A]

[A]

[A]

Wire saw

Somewhat Applicable

Somewhat Applicable

Not Applicable

[A]

[A]

[A]

[A]

[A]

Hand saw

Somewhat Applicable

Somewhat Applicable

Not Applicable

[A]

[A]

[A]

[A]

[A]

Ultrasonic core drill

Somewhat Applicable

Somewhat Applicable

[A]

[A]

[A]

Somewhat Applicable

[A]

[A]

[A] Not yet

Hydraulic cutter

Somewhat Applicable

[A]

[A]

[A]

[A]

Somewhat Applicable

[A]

[A]

[A]

ChiselSomewhat Applicable

[A]

[A]

[A]

[A]

[A]

[A]

[A]

[A] Not yet

AWJ

Somewhat Applicable

Somewhat Applicable

[A]

[A]

[A]

Not Applicable

Not Applicable[A][A] Finished[A]

Somewhat Applicable[A]

Somewhat Applicable[B]*1

Somewhat Applicable

Not Applicable[A][A] FinishedPlasma arc

Not Applicable

Not Applicable[A]

Somewhat Applicable

Not Applicable

Somewhat Applicable

Not Applicable[A]

Plasma jet[A]

Somewhat Applicable[A]

Somewhat Applicable

Not Applicable

Somewhat Applicable

Not Applicable

Not Applicable

Not Applicable

Somewhat Applicable[A]

Somewhat Applicable

Not Applicable

Somewhat Applicable

Somewhat
Applicable[A]

Laser gouging

Gas

Total evaluation/element tests

Processing methods
Not Applicable[A]
Not Applicable
Somewhat Applicable
Somewhat
Somewhat for which element
Contact arc
Applicable
Applicable tests have not yet
Somewhat Applicable
Not Applicable
Not Applicable
Not Applicable
Not Applicable
Somewhat Applicable
Somewhat
Somewhat been performed are
Arc saw
Applicable
Applicable subjected toSomewhat Applicable
Not Applicable
Not Applicable[A]
Not Applicable
Somewhat Applicable
Not Applicable
Somewhat assessment for
Consumable
Applicableselection in terms ofelectrode WJ
the capability to[A]
Somewhat[A][A]
Not Applicable
Somewhat Applicable
Not Applicable
Somewhat
Laser boring
Applicable
Applicable process MCCI debris*1: It was confirmed, based on the outcome of research activities in last fiscal year that the aerial diffusion of chips and dust generated by the laser gouging can be inhibited by washing the chips and dustin the PCV bottom
Not Applicable

Somewhat Applicableby water flow, although the process is performed in the atmosphere.

©International Research Institute for Nuclear DecommissioningNo.42

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting
methods(1) A processing element test with chisels⚫ General information about chisel processing➢ A processing method to crush target materials by hitting them with a crushing bit
attached to the front end of heavy machinery. It is used at civil engineering work sites.
➢ This method is widely used.
➢ Specifically, it is generally used to bore through bedrock, break rocks into small pieces,and crush concrete.
➢ In FY2015-FY2016, preliminary tests to crush concrete blocks, using the combination ofa muscular robot and chisel processing, were performed.
Fragments of crushedconcrete blocks

Chisel processing tool
Muscular robot arm

Concrete blocks

Concrete block crushing test by a chisel processing method©International Research Institute for Nuclear DecommissioningNo.43

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting methods(1) A processing element test with chisels⚫ Purpose of development➢ Verification of the chisel processing method’s applicability to fuel debris retrieval.
✓ Improvement of efficiency in collecting MCCI debris to about 90%.
✓ Assessment of the feasibility of a high speed processing method applicable to MCCI
debris.
✓ Assessment of the feasibility of a dust collection technology applicable to chips andfragments generated by a chisel method.
✓ Investigation of the characteristics of processing liquid waste that contains chips andfragments generated by a chisel method.
⚫ Issues to be resolved➢ The target duration of the fuel debris retrieval project is 10 years, and fuel debris of 300 kg must
be processed daily to achieve this target. However, existing processing methods cannot achieve
this goal. Therefore, the feasibility of a high-speed processing method needs to be examined.
⚫ Development approach➢ Evaluation items in FY2015-FY2016✓ Phase 1: Applicability evaluation through desk study✓ Phase 2: Implementation of preliminary tests➢ Evaluation items in this project✓ Phase 3: Conceptual study and element test planning✓ Phase 4: Manufacturing prototype units for testing and implementing element tests©International Research Institute for Nuclear DecommissioningNo.44

6. Implementation Details
6.2. Implementation Details

1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting methods(1) A processing element test with chisels⚫ Expected results➢ Feasibility of basic processing methods applicable to MCCI debris➢ Throughput calculation.
➢ Result of the size distribution of particles contained in MCCI processing liquid waste.
➢ Issues concerning MCCI debris processing.

©International Research Institute for Nuclear DecommissioningNo.45

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting methods(1) A processing element test with chisels

Since relevant analysis results suggest that the chisel processing method is highly capable of handling MCCI debris
that constitutes most of the fuel debris, element tests for this method were performed.
Type of fueldebris

RPV
core

RPV
bottompart

Major fuel debris

Size

Powdery,
GrainedAdhered to or stacked onresidual structures

Molten core materials are rapidly cooled down into small
pieces

A few μm - a few cm

Powdery,
Grained

Most of the debris in thisarea consists of crust

Molten core materials are rapidly cooled down into small
pieces

A few μm - a few cm

Lumps form

Crust contains Zr alloy and
ZrB and partially rigid andtoughSlowly cooled to form lumps

Structure plus
adhered fuel debris

MCCI
Crust

MCCI
Crust/lump MCCI
debris4 m or less

Fuel debris formed by molten metals and oxide fuelmixing and solidifying
Fuel debris attaching in
gaps inside the tubes andon the outer surfaces

Fuel debris clogged the flow passage of lower SUS
tubes from the bottom end of the pressure vessel

The debris forms multiple
layers; most are likely toconsist of MCCI debris
lumps

Molten reactor core materials leaked out of RPV,
dispersed, and quenched
Crust fractured during MCCI and broken into small
fragments due to ejection of molten corium

Large amount of brittle,
highly porous fuel debris
accumulated

Ejected materials containing metal components adhere to the wall
surface. Debris on the floor has a hollow structure, and the crust in
the upper part is porous, with fewer metal components.

Thickness
A few dozen cm
7-20

The layer separation inside
the pedestal is unclear;
there is a crust and MCCI ina lumpy form.

50 μm-20 cm

Thickness 0.1-1 m
120-209

Upper part consists of rigid corium with high porosity
Lower part is rigid with a low porosity
Metallic balls are in the central area and near the wall

A few dozen cm or more

Under study

There exist grained fuel debris leaked from Pedestal

Corium leaked from the pedestal reacted with theconcrete and solidified
Slightly rich in metal component

Thickness
0.1-1 mPenetration depth
10 and a few cm

Debris distributed relatively uniformly in the bottom of the
MCCI

Metal layer
MCCI/powdery
GrainedSome fuel assemblies remain without melting down

0-3

MCCI in lump form

OutsidePedestal

MAAP
All fuel assemblies may
have melted down, butsome could remain

MCCI/powdery
GrainedInsidePedestal

Fuel debris properties

Fuel rod stubs(unmolten fractured
fuel)

Crust
(bedrock)
CRD/inst
rumentat
ion
guide
tube

Mass [t]Features

50 μm-20 cm
70-153
0.5 m or less©International Research Institute for Nuclear DecommissioningNo.46

6. Implementation Details
6.2. Implementation Details

1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting
methods(1) A processing element test with chisels
Chisel processing was tested with the MCCI-simulating test facility (provided by Hitachi-GE Nuclear Energy).
Based on the preliminary test result, chisel processing tests and testing equipment are being planned.
Processing scene/shape of chisel

Processing result status

Processing speed*1

No.

Type of chisel

Number ofchisels

1

Electrically driven
unit

1

28.74 kg/h*1(287 kg/day*1)

2

Electrically driven
unit

1

43.38kg/h*1(433 kg/day*1)

3

Air driven unit

2

255.576kg/h*1(2.5 tons/day*1)

Notes*1: Data of a processing speed is for reference purposes only since these are preliminary test results with test blocks provided by a vendor. The target processing speed is 300 kg/day.
Work time is 10 hours per day.
©International Research Institute for Nuclear DecommissioningNo.47

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting
methods(2) A processing element test by ultrasonic core boring⚫ Purpose of development➢

A processing method with less reaction force and less dust diffusion need to be developed.
✓ Features of ultrasonic core boring•
The reaction force is smaller compared to a standard core boring.
(A load of up to 1.5 tons was applied in the element test with a bit of ⌀66 mm
performed last fiscal year)•
Developed for a planetary exploration project. There are successful results forprocessing various types of hard materials.
•
Compact and lightweight⚫ Issues to be resolved➢

The applicability of ultrasonic core boring to fuel debris processing must be verified.
✓ Workability (processing speed) of materials including metals (partly expected to be rigid)✓ Particle size distribution of secondary waste products contained in processing liquid
waste✓ Robustness (in standard use, processing conditions such as type of bit and ultrasonicwave [or sound wave] is changed depending on the characteristics of materials to beprocessed. Applicability to fuel debris on 1F, whose characteristics are inferred to beheterogeneous, is not specific yet)
✓ The bit shown in the photo on the right has a diameter of about 3 mm. The diameter of acore bit needs to be increased to increase processing speed.

©International Research Institute for Nuclear DecommissioningNo.48

6. Implementation Details
6.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting
methods(2) A processing element test by ultrasonic core boring⚫ Development approach➢➢

The development process is divided into three phases since applicability to fuel debris on 1F is uncertain.
✓ Phase 1: Applicability evaluation and test planning through desk study✓ Phase 2: Applicability evaluation by element tests✓ Phase 3: Prototype tests
Before proceeding to the next phase, expert review is provided⚫ Expected results➢➢➢

Processing conditions and performance (processing speed) in processing various materials including metals ->Specification of throughput evaluation
Result of particle diameter distribution in processing liquid waste -> Result is input to System Project
Issues concerning processing -> Applicability to actual equipment on 1F/development issues⚫ Development goals➢➢

Processing speed✓ The final goal is to achieve a processing speed of 30 kg/hr or higher in the processing test with the test material
that simulates MCCI debris in the Pedestal bottom.
✓ The element tests conducted in Phase 2 will assess whether the final target speed or a higher speed can beattained.
Mass of processing tools✓ The target mass of processing tools is 50 kg or less in consideration of the maneuverability of robot arms that
hold the handling tools and carry them near fuel debris by remote control.
©International Research Institute for Nuclear DecommissioningNo.49

7. Implementation Details
7.2. Implementation Details

1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting methods(2) A processing element test by ultrasonic core boring⚫ Test Conditions➢ Test block (under plan):✓ Unit test blocks alone and combinations of different unit test blocks
Material

Hardness

Stainless steel

1.5-3 GPa

Zirconia (ZrO2)

12-14 GPa

Alumina (Al2O3)

15-17 GPa

Concrete-

Stainless steel + ZrO2 or Al2O3-✓ Simulated fuel debris (cold)• The fuel debris simulant test material shall be made to simulate MCCI debris in thepedestal bottom.
• Test block specification will be determined from now➢ Measurement of secondary products generated (under plan):✓ As with the core boring tests conducted up until last fiscal year, measuring the sizes of theparticles in processing liquid waste is planned©International Research Institute for Nuclear Decommissioning

No.507. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting
methods(2) A processing element test by ultrasonic core boring⚫ Test procedures and criteria
Items

Criteria/targets

Element tests/prototype tests

Notes

Processing speed

30 [kg/hr] or higher

300 [kg/day] is targeted

Weight50 [kg]Manipulator capacity is taken into
account

Boring diameter

Seeking to achieve 75 [mm] or larger

This test corresponds to the core
boring test (66 [mm]) conducted in
the previous year

Water volume

Target: 0.004 [m3]Collection ability is taken into account

OthersCollect and analyze chips and crumbs with asize of 0.1 [μm] or larger

Results are reflected to chip andcrumb collection systems*Criteria/targets may change depending on the progress of study.

©International Research Institute for Nuclear Decommissioning

No.51

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemb. Processing element tests with fuel debris simulant by effective processing/cutting methods(2) A processing element test by ultrasonic core boring
FY2017 (Heisei 29)

Items to study
4

Key milestones

5

6

7

8

Phase 1: Desk study

9

10

Plan

11

FY2018 (Heisei 30)
12

1

2

3

4

5

Decide whether toproceed to Phase 2

6

7

8

9

10

11

12

1

2

Decide whether toproceed to Phase 3

a. Conceptual study/test plan
1. Development plan
2. Conceptual Study
3. Test planning

Phase 2: Element tests

b. Test preparation/test device
test production

c. Element Test
1. Element tests(fundamental tests)
Phase 3: Prototype test production and tests
2. Prototype test production
3. Prototype tests
d. Summary

Notes

Expected results[1] Processing conditions and performance (processing speed) in processing various materials including metals -> Specification ofthroughput evaluation[2] Result of particle diameter distribution in processing liquid waste -> Result is input to System Project[3] Issues concerning processing -> Applicability to actual equipment on 1F/development issues©International Research Institute for Nuclear Decommissioning3

No.52

7. Implementation Details
7.2. Implementation Details

1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection systemc. Producing simulated fuel debris and mock-up contaminated structures used for processing tests• Conceptual study of test facility is underway based on the MAAP analysis result. Test production of the MCCI
test facility to be processed is planned in cooperation with the Fuel Debris Characterization Project team.
About the melting test furnace

Requirements of MCCI test facility to beprocessed
Information on the final solidification state uponcompletion of MAAP evaluation (FY2015 Report
received 14 days later) was reflected. (updated to thelatest study status)

Determination of test facility test
production method (proposed).
Graphite electrode(4 inches)

Graphite crucible

Determination of the components (idea) of MCCI
debris simulant test material.

Determination of the (proposed) test
facility dimensions required forprocessing tests.

Molten metal(molten raw material)
Heat insulation fiber
board

No.
1

Component
Ceramics

Input
quantity(liter)
2.26

2
3

Metal

1.12

4
5
6

Concrete

58.36

Mixingratio

Density(kg/m3)

Input
quantity
(kg)

ZrO2

25%

5.65

3.19

CeO2 (simulating UO2)

75%

7.2

12.2

SUS

95%

7.6

8.09

Zr or Zry

5%

6.52

0.36

Cement

15%

3.5

30.6

Aggregate (SiO2)

85%

2.65

131

Composition

Approx.
300 mm

Sandblasting sandAmorphous
refractory material

Approx. ⌀550 mm

Schematic illustration of test production of MCCI test facility to be processed©International Research Institute for Nuclear Decommissioning

No.53

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[2] Development of a fuel debris cutting/dust collection system
d. Study and analysis of dust collection systems used for chips and dust generated during cutting work
• Local collection systems applicable to chisel processing are under consideration.
• Methods to collect chips and dust generated during element tests for cutting methods, and to analyze thecollected chips and dust, will be coordinated from now.
Transferring toUC

Local collection flow ofprocessing
Fuel debris (MCCI) is processed bychisels in the area within thecontamination spread prevention
sheet.

Hoisting and lowering local
collection equipment is assumed

Compact submergible pump(can be lowered for sucking
operation)

Crushed debris are suctioned by thecompact submergible pump.

Fuel debris is sent to the unit canthrough a suction hose.

Four chisels

Diffusion prevention
sheet(with brush tip)

Schematic illustration of local collection equipment for chisel processing

Diffusion prevention
sheet(with brush tip)

Hood top end fits the shape
Processing using four chisels(can be lifted for thesuctioning operation)
Fuel debris(MCCI debris)

Schematic illustration of local collection task during chisel processing©International Research Institute for Nuclear Decommissioning

No.54

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system[2] Development of a fuel debris cutting/dust collection system[3] Development of methods to prevent fuel debris diffusion
2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell[2] Technical development for removing interfering objects during fuel debris retrieval
3) Development of remote maintenance technologies for fuel debris retrieval equipment
4) R&D management©International Research Institute for Nuclear Decommissioning

No.55

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamber⚫ Purpose of development➢ Feasibility verification of a method to prevent fuel debris diffusion that can be arranged adjacentto the debris processing point.
➢ Identification of issues concerning fuel debris diffusion prevention methods.
⚫ Issues to be resolved➢ Fuel debris fragments produced by processing fuel debris in and outside the pedestal may
spread by the contaminated water flow and diffuse in the S/C through the jet pump diffuser.
➢ The fuel debris retrieval project duration may be prolonged if fuel debris diffuses in the S/C andother areas since the area to be worked on for fuel debris collection expands.
➢ If fuel debris already exists in the S/C and other areas now, there is a risk of another criticality
due to diffusion of additional fuel debris.
➢ Remote controlled workability for narrow partss.
⚫

Development approach➢ Phase 1: Conceptual study of contamination spread prevention methods➢ Phase 2: Selection of contamination spread prevention methods➢ Phase 3: Element test planning➢ Phase 4: Manufacturing prototype units for testing and implementing element tests©International Research Institute for Nuclear Decommissioning

No.56

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamber⚫ Expected results➢ Feasibility of a contamination spread prevention method by jet deflector.
➢ Clarification of issues concerning contamination spread prevention methods and theestablishment of a development plan.

Place to be applied for thecontamination spread prevention
method©International Research Institute for Nuclear Decommissioning

No.57

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamberContamination spread prevention method No. 3 was selected as the most feasible according to the conceptual study
result. Steps necessary to embody the method will be studied along with planning the element tests to verify feasibility.
The element tests will be performed according to the plan.

No.

Methods overview

Contamination spread
prevention effect
In air1

Fuel Debris

Underwater

Difficulty levelof method(assumed)

Closure plates are
welded or jointed byequivalent means

Notes

Remote welding in a narrow
space will be difficult

High

High

High

Thickening the wall toform dike by welding

2

Medium

It is assumed that contamination
spread through the air will occur
in combination with the negative
pressure control system.

Medium

It is assumed that contamination
spread through the air will occur
in combination with the negative
pressure control system.

Fuel Debris

Dike installed

Low

High

3
Fuel Debris

Install closure plates

Dike installed

MediumHigh©International Research Institute for Nuclear Decommissioning

No.58

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamber

Schematic illustrations of element tests to verify of the method are shown below. Workability under a low water level will
be examined and issues will be identified.

Hoist

Hoist

Manipulator arm

Water level

Dike

Schematic illustration of dike installation

Manipulator arm

Water level

Closure plate

Schematic illustration of closure plate installation©International Research Institute for Nuclear Decommissioning

No.59

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamber

Specific design of the contamination spread prevention dike is being studied based on the investigation of Unit2 PCVinternal conditions so that the spread of the contamination is confined within a minimum area while the installation areaof the dike is minimized.
Water level in Unit2: 300 mm(assumption)

Worker access port

The worker access port and the sump pit are consideredpassages through which fuel debris in the pedestal spreadoutside the pedestal.

Dike: approx. H650 mm(proposed)

Measures for contamination spread prevention were studied
based on the assumption that most of the fuel debris is
inside the pedestal.
Jet deflector

Part of fuel assembly
Pedestal inner wall

Grained debris deposit

Dike for sump pit
Sump pit

Areas to be protected by dike canbe narrowed when all jet deflector
are completely closed.
It is under consideration what
equipment is necessary toconstruct the dike.

Investigation result of internal conditions of
the Unit2 PCV
Photo of the pedestal bottom

Dike for worker access port
©International Research Institute for Nuclear DecommissioningNo.607. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamber

As with Unit2, a method that can minimize the construction work to prevent the spread of contamination was studied
with Unit1.
Deposit: 200 mm (estimate)
Deposit: 900 mm (estimate)

Although the total span of the dike to be constructed could beshorter compared to the case where dike is constructed around alljet deflectors, the water level needs to be lowered after removing thedeposit.
The equipment needed to install the dike is under consideration.

Dike for sump pit
Spread of fuel debris: approx. 100° (assumed)

Dike
Contaminatedwater

Dike for worker access port
Deposit

Fuel Debris
Schematic diagram of estimated debris spreading condition at present in Unit1

Schematic illustration of minimum contamination spread prevention for Unit1©International Research Institute for Nuclear DecommissioningNo.61

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamber

As part of the efforts to study dike construction equipment, a preliminary test and the identification of issues based on
the test result is underway, where a flexible structure arm (muscular robot) developed in FY2016 is subjected to further
study.
Policy for the developing a flexible structure arm for dike
construction• Development shall be conducted in such a way that results
will be applicable not only to dike construction but also tofuel debris retrieval work conducted outside the pedestal
and to the removal of interfering objects existing outside.
Equipment applicable to various works with high efficiency
can be realized.

Flexible structure arm base(Jet deflector platform)

Jet deflector test mock-ups

Closure plateJet deflector test mock-ups

Flexible structure arm for dike
construction(utilizing the one developed in FY2016)

Preliminary test status of closure plate installation

Dike

A preliminary testing to study dike construction equipment

Besides the construction of a dike to prevent contamination
spread, installing closure plates around jet deflectors isplanned to prevent aerial contamination spread; methods
for installing closure plates are under consideration.
(Photos show closure plate installation test by workers)©International Research Institute for Nuclear DecommissioningNo.62

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[3] Development of methods to prevent fuel debris diffusiona. Preventing contamination spreading to the suppression chamber
FY2017 (Heisei 29)

FY2018 (Heisei 30)

Items to study
4

Key milestones

5

6

7

8

9

10

11

Interim report


12

1

2

3

4

5

6

Annual report


7

8

9

10

11

Interim report


12

1

2

Annual report

1. Conceptual study

2. Element test plan
3. Preliminary tests
required for element
test plan
4. Element test preparation(Test device production)
5. Element Tests

6. Wrap-up

Notes

3

Results of element tests
1. Feasibility of a contamination spread prevention method by jet deflector.
2. Identification of issues in installation methods.

©International Research Institute for Nuclear DecommissioningNo.63

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system[2] Development of a fuel debris cutting/dust collection system[3] Development of methods to prevent fuel debris diffusion

2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell[2] Technical development for removing interfering objects during fuel debris retrieval

3) Development of remote maintenance technologies for fuel debris retrieval equipment
4) R&D management©International Research Institute for Nuclear DecommissioningNo.64

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment

Develop the following remote technologies for each task assumed during fuel debris retrieval
because the site is highly radioactive, and many of the tasks must be remotely controlled:[1] Element technology development related to work cell
Remote operation is required to install work cells that enclose fuel debris retrieval equipment. In the side entry method,for example, the airtightness and strength of work cells and the access passage to the PCV (X-6 penetration, etc.),
which runs through a narrow and highly radioactive area in the reactor building, must be ensured. As with the top entry
methods, the same requirements apply to work cells and the access passage, which is installed in a high radiation areaon the operation floor right above the reactor well.
Among other things, the following main themes with element tests will be performed on an as needed basis. Throughthese activities, issues will be identified and reviewed.

a. Improvement of work cell manageability by establishing work cell installation methods for
top entry and side entry and also by reducing the load on the reactor building• Design conditions applicable to cell/method review is under optimization.
• Conceptual study concerning the soundness of the reactor building after installing the facilities and equipment
necessary for a the side entry method (seismic resistance, impact of additional openings constructed in thebuilding, load on the floor, etc.) and the feasibility of installation work (cell installation procedures, etc.) isplanned.

b. Work cell sealing method (such as welding, inflate sealing or water sealing)• Feasibility of the welding-based sealing method was proved by element tests performed until the last fiscal year.
• Element tests for the inflation sealing method are planned.

c. Assurance of work cell sealability and dust dispersion prevention performance• Regarding work cell sealability and dust dispersion prevention performances, confinement performance tocontain specified radioactive materials within the cell, working with the negative pressure control system on thesystem side, is being studied.

©International Research Institute for Nuclear DecommissioningNo.65

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell
⚫ Purpose of development➢ Improve work cell feasibility, including cell installation methods and reactor building strength
check, by identifying requirements for work cell(s) and clarifying concept of cells.

⚫ Issues to be resolved➢ Clarification of concept of cells✓ Clarification of source term and maintenance areas✓ Study a way to share a work cell with multiple types of robots✓ Clarify maintenance items and methods for equipment in the cell
✓ Enhancement and cost reduction of shielding door, double door system, and airlock system✓ Increase fuel debris collection speed (throughput) by clarifying in-cell processes✓ Reduce the shielding structures’ weights➢ Clarify the cell installation method✓ Detailed study of methods to open a through hole in the PCV concrete✓ Study of dust dispersion prevention methods (especially a method applicable to gaps between
the PVC wall and concrete structure)✓ Clarify the installation method for heavy weight objects under a high-dose radiation
environment©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.66

7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell
⚫ Development approach➢ Clarify work cell requirements➢ Clarification of concept of cells✓ Mapping the required functions for each different cell type
✓ Estimation of fuel debris properties and amount of those handled✓ Calculate the thickness of shielding structures for cells✓ Study of cell structures✓ Study of parts and devices to complete a cell (shielding door, sealing door, handlingequipment, etc.)➢ Clarify the cell installation method✓ Study of methods to open a through hole in the PCV concrete✓ Study of methods for sealing between PCV and cell
✓ Study of cell carrying-in methods➢ Verification of the building strength✓ Assess the impact of additional openings constructed in the building on its strength✓ Assess the impact of cells installed in the building on its strength⚫ Expected results➢ Feasibility of a series of processes from carrying in equipment and materials in PCV to the removal offuel debris and interfering objects➢ Fuel debris collection speed (throughput) by clarifying in-cell processes©International Research Institute for Nuclear DecommissioningNo.67

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell
Clarification of cell-related issues based on safety requirements
Basic safety
requirements

Confine radioactive
materials by setting aboundary

Safety Requirements(Example)

Prevent leakage that exceeds
the allowable level specified
in the safety standards forradioactive materials in gas

Protect against
external exposure

Shields for preventing
excessive direct radiation
exposure

Design for dose
reduction for workers

Shields, appropriateclassifications for the level ofcontamination and dose, andsystem designs for remote
maintenance and traffic line
setting, etc. to reduce
exposure

Operation control fordose reduction forworkers

Operation methods,
maintenance plans, and task
management for dose
reduction

Issues concerning cells

Confinement by
establishing astatic boundary

Confinement by
establishing a
dynamic boundary

Methods to resolve issues

Sealing of cell (including
door system and throughholes)

Conceptual study based on proven technologies

Sealing of connections
between the PCV and cells

Sealability will be examined in element tests since
there is no record of similar applications

Door system

Conceptual study based on proven technologies(such as double door and airlock)

Shielding of cell from external

Clarification of source term and the transportationline of wastes, and implementation of conceptual
study

Shielding cells from worker access areas

Clarification of areas workers are allowed to enter,and implementation of a conceptual study

Carrying-in, installation and layout of cells andtraffic lines

Conceptual study by clarification of in-cellprocesses

Maintenance of cells and equipment

Conduct a conceptual study by clarifying equipment
to be maintained, maintenance methods, andmaintenance space or rooms
Element tests are planned where necessary

Function allocation among cells, layout, and traffic
lines

Conceptual study by clarification of in-cellprocesses

Maintenance of cells and equipment

Conduct a conceptual study by clarifying equipment
to be maintained, maintenance methods, andmaintenance space or rooms
Element tests are planned where necessary©International Research Institute for Nuclear DecommissioningNo.68

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improve work cell manageability by establishing work cell installation methods for top entry and side entry
and by reducing load on the reactor building Design conditions applicable in cell/method review
Inputs that could be reflected on the design conditions concerning cell and method study were organized andhypothetical conditions for items for which useful information was not input was set. Note that the conditions may
be updated when a new input becomes available.
Item

No.

Detailed item

Design conditions, etc.

Item No.1
Radiationrelated items

1

Source strength offuel debris

The source strength after a cooldown period of 10 years that is
described in JAEA-Data/Code 2012-018 is used.

2

Radiation dose in the
PCV

1. Inside the pedestal (same for Unit1-Unit3)
100-1000 Sv/h
2. Outside the pedestal (same for Unit1-Unit3)
10-100 Sv/h

3

Radiation dose in
R/B

Current radiation doses in each area shall be used.

4

Radiation dose on
the outer surface of acell shielding
structure

1. Restricted areas for worker in a normal condition: 1 mSv/h orless
2. Worker accessible areas: 0.1 mSv/h or less
3. Radiation dose is determined through coordination with the
System Project team.

Notes

The fall of reactor
internals and resultsof site survey aretaken into account©International Research Institute for Nuclear DecommissioningNo.69

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improve work cell manageability by establishing work cell installation methods for top entry and side entry
and by reducing load on the reactor building Design conditions applicable in cell/method review
Item

No.

Item No.2
R/B andseismic
resistance

Item No.3
Dimensions of
openings foraccessconstructed on
the wall of PCV
and inside
Pedestal

Detailed item

Design conditions, etc.

Notes

1

Acceptable maximum
load of floors above
ground

1. Unit1: 1.22 ton/m2 in front of X-6 penetration, and 4.88 ton/m2 in front of the
manhole2. Unit2/Unit3: 4.9 ton/m2 in front of X-6 penetration, and 1.22 ton/m2 in other areas

2

Seismic acceleration

1. Seismic acceleration of 900 Gal is assumed.
2. To be determined through coordination with the Antiseismic Project team.

3

Cell height

1. The height of cells installed in R/B shall be equal to or less than the height of theceiling of R/B 1st floor.
2. The height of each cell varies with the processing method depending on required
functions.

1

Equipment hatch size1.
Unit1: ⌀3.0 m
2. Unit2/Unit3: H2.5 m

2X-6 penetration openingsize

1. Whether it is usable as an access port and whether the opening needs to beenlarged depends on the construction method.
2. Conditions of the opening after completing sampling work and conditions fortaking over will be coordinated with the Sampling Project team.

3

Pedestal opening size

1.

4

Pedestal strength

1. It is assumed that the pedestal retains the original strength.
2. Integrity of the pedestal will be verified by internal investigation and other means.

5

Water levels in the PCV

1. The water level in the PCV can be controlled.
2. The water level in the PCV is assumed to be equal to or lower than the height of
the 1st floor of R/B. (for a the side entry method)

Unit1, CRD opening: H1970 mm x W790 mm
Worker access port: H1724 mm x W755 mm
2. Unit2/Unit3, CRD opening: H1900 mm x W750 mm
Worker access port: H1900 mm x W750 mm©International Research Institute for Nuclear Decommissioning

No.707. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improve work cell manageability by establishing work cell installation methods for top entry and side entry
and by reducing load on the reactor building Design conditions applicable in cell/method review
Item
Item No.4
Fuel Debris
Collection
methodNo.

Detailed item

Design conditions, etc.

1

Definition of debris

1. Debris that exists in the area under the upper grid plate (except CRD rail) is treated as fueldebris.
2. As with the outside pedestal, material that leaks from the pedestal through the worker accessgate is treated as debris.

2

Lump debris

1. Debris whose diameter exceeds 10 mm is defined as "lump debris".
2. Any debris lump that is larger than the unit can will be collected after crushed into pieces ofsmaller size.
3. Debris lumps that fit into the unit can will be collected as they are without crushing.

3

Particle debris

1. Debris with a diameter of 0.1 mm to 10 mm is defined as "particle debris."
2. Collected by suction or equivalent means.

4

Powder debris

1. Debris with a diameter of less than 0.1 mm is defined as "powder debris."
2. Collected by suction or equivalent means.
3. If debris is collected in the water treatment system of the plant, concrete method will bearranged separately down the road.

5

Criticality of debris

Methods for controlling criticality recurrence will be coordinated with the Criticality Project Team.

6

Areas to conduct debris
collection work in

1. Inside the pedestal, collection in all areas to a depth not less than the drain sump pit or depth.
2. Outside the pedestal, collection in all areas to a depth not less than the drain sump pit or
depth.
3. Specific collection work areas will be determined based on the investigation and sampling
results.

7

Method to process lumpdebrisSee sections concerning fuel debris cutting and dust collection systems in this report.

8

Unit Canister

1. ⌀400 mm x H400 mm or smaller
2. A diameter of 200 mm is used initially, and the method study team will determine a new
dimension within the range suggested by the Canister Project Team.

Notes©International Research Institute for Nuclear Decommissioning

No.71

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improve work cell manageability by establishing work cell installation methods for top entry and side entry
and by reducing load on the reactor building Design conditions applicable in cell/method review
Item

No.

Detailed item

Design conditions, etc.

Item No.4
Fuel Debris
Collection
method9

Storage Canister

1. ⌀400 mm x H2000 mm or smaller
2. A diameter of 200 mm is used initially, and the method study team will determine
a new dimension within the range suggested by the Canister Project Team.

10

Cask

Transfer cask specifications will be determined through discussions with theCanister Project Team.

11

Dewatering and dryingof debris

1. The unit shall be designed so that it can dewater debris in it.
2. When the control of the fuel debris fluid is judged effective for hydrogengeneration, according to the Canister Project Team’s reevaluation, dewateringand drying methods will be studied further as needed basis.
3. The debris fluid shall be discussed with the Canister Project Team and the
Criticality Project team to determine whether the canister of ⌀400 mm is used,which may pose a risk of criticality subject to its shape.

12

Measures for hydrogengeneration from debris

1. Waiting for evaluation by Canister Project Team
2. The control of fuel debris fluid and/or the vent of containers shall be studied
when needed to measure for hydrogen generation during fuel debris
transportation.

13

Material accountancy
items for unit canMaterial accountancy related to safeguards is studied by the initiative of JAEA
separately from the subsidized project.

14

Material accountancy
items for canister

1. Material accountancy related to safeguards is studied by the initiative of JAEA
separately from the subsidized project.
2. The gross mass of each container will be measured by a typical weighing
method.

15

Inspection and material
accountancy items forcask before carrying-out

Material accountancy related to safeguards is studied by the initiative of JAEA
separately from the subsidized project.

Notes©International Research Institute for Nuclear Decommissioning

No.72

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improve work cell manageability by establishing work cell installation methods for top entry and side entry
and by reducing load on the reactor building Design conditions applicable in cell/method review
Item
Item No.5
Collection ofinterfering objects
and wastes

No.

Detailed item

Design conditions, etc.

Notes

1 Definition of interfering
objectAny object that needs to be removed for fuel debris retrieval is defined as"interfering object."

2 Radiation dose ofinterfering objects

1000 Sv/h or less3 Way to discern "debris"from "waste"

Definitions of "fuel debris" and "waste" are being discussed by anotherproject team.

4 Order of interfering object Objects to be removed and dismantlement range vary with the processing
dismantlement
method.
5 Waste collection can

1. The can shall be designed so that it can dewater wastes in it.
2. The can dimensions shall be determined so that it can pass throughopenings constructed in the PCV.

6 Waste removal container

Details will be studied in the waste project.

7 Interfering object
processing and severing
methodDifferent processing and severing methods need to be studied since a
suitable method depends on the types of obstacles to be processed andthe area of removal work.

8 Criteria to approve thecarrying-out of wastes

1. Each waste removal container shall be inspected for radiation dose,among other things, before leaving the facility.
2. Criteria will be studied in the Waste Project.
©International Research Institute for Nuclear Decommissioning

No.73

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improve work cell manageability by establishing work cell installation methods for top entry and side entry
and by reducing load on the reactor building Design conditions applicable in cell/method review
Item

No.

Detailed item

Design conditions, etc.

Item No.6
Operation andmaintenance ofaccess equipment

1

Carrying-in/out ofaccess equipment

1. Keep the boundary during carrying-in/out tasks.
2. The access equipment varies with the processing method.

2

Utility supply to accessequipment

1. Required utilities depend on methods.
2. The drive source for access equipment varies depending on thetechnical method (such as oil hydraulics, water hydraulics orelectricity).

3

Maintenance of accessequipment

1. Simple maintenance tasks such as camera exchange will be
performed in R/B remotely.
2. Maintenance items vary with the processing method.

4

Camera exchange

The camera shall has radiation resistance of 100 kGy.

5

Access equipment
exchange frequency

The target radiation resistance of access equipment is 1×106 Gy.

6Emergency retrieval ofaccess equipment

1. Access equipment shall be designed and installed so that it can beremoved in case of failure.
2. The emergency collection method varies with the processing method.

7

Exchange of tip tools

The method to exchange tip tools varies with the processing method.

Notes©International Research Institute for Nuclear Decommissioning

No.74

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improve work cell manageability by establishing work cell installation methods for top entry and side entry
and by reducing load on the reactor building Design conditions applicable in cell/method review
Item
Item No.7
Cell operation
andmaintenanceNo.

Detailed item

Design conditions, etc.

1

Fuel debris retrieval rate

The target rate is 300 kg/day.

2

Classification of cells bycontamination level

Cells are classified into three areas by contamination level: high-level contaminated, mid-levelcontaminated, and low-level contaminated areas.

3

Negative pressure control
in a cell

1. The pressure of the secondary boundary shall be maintained at around -64 PaG. (Pressure
difference to the atmosphere)
2. A differential pressure of about 100 PaG per contamination classification difference shall bemaintained at the primary boundary between two adjacent cells.

4

Cell ventilation

1. The cell shall be equipped with a ventilation system to cope with hydrogen generation.
2. Nitrogen use needs to be discussed with the team responsible for the system of the plant.

5

Cell operation andmaintenance

1. The operation and maintenance of a cell is implemented by remote control in principle.
2. Tasks by workers shall be considered only in case of emergency where the remote systemdoes not work.

6

Cell location

1. An extension building shall be constructed outside R/B.
2. Layout inside R/B and layout outside R/B vary with the processing method.

7

Method to monitor
conditions in of a cell

Temperature, pressure, radiation dose, neutron dose, hydrogen concentration, oxygen
concentration, visual observation, etc. in a cell shall be monitored.

8

Debris and waste transfer

1. Take contamination spread prevention measures during transfer.
2. A definitive transfer means is casks.

9

Cell installation method

The cell installation method varies with the processing method.

10

Connection of a cell and
the PCV

1. Connection shall take into account contamination spread prevention and confinement
2. The connecting method and technology vary with the processing method.

11

Method to decontaminate
the inside of a cell

1. Specific decontamination methods shall be studied.
2. The decontamination methods and means vary with the processing method.

Notes©International Research Institute for Nuclear Decommissioning

No.75

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improvement of work cell manageability by establishing work cell installation methods for top entry and side
entry and also by reducing the load on the reactor building Study concerning reduction of load to the reactor building• Measures to meet the load capacity of each floor were studied to reduce the load exerted to the reactor
building.
PLAN-A

PLAN-B

PLAN-C

Layout example (Unit2)

Layout example (Unit1)

Layout example (Unit2)

Carry-in Crane

Equipment Transport
Carriage

Cask

Equipment Hatch Cell

Extension
Building

Maintenance Cell

Equipment
Cell

Opening on the R/B Wall

R/B WallFuel Debris Retrieval
Cell

Cell carriage system

Storage
CanisterCarrying-in/out
of others thandebrisWaste Transport
Carriage

PCV wallPedestal

Waste Transport
Cell

Mini-Cask System

•
•
•

•

•

Cell Weight in
R/B

Floor
Loading

Floor Loading
Capacity

Cell Weight in
R/B

Floor
Loading

Floor Loading
Capacity

Cell Weight in
R/B

Floor
Loading

Floor Loading
Capacity

Weight Reduction
under Consideration≤ 4.9 ton/m2

4.9 ton/m2

800 tons

0 ton/m2

4.88 ton/m2

Weight Reduction
under Consideration

7 ton/m2 or less

4.9 ton/m2

This plan is based on the idea to lay out all cells straight andconstruct a relatively large opening in the outer wall of the R/B.
The cells are carried in and installed via conveyor rails from outside
the R/B.
The reinforcement of the opening needs to be considered to maintainthe integrity of the R/B (since the opening imposes a relatively large
load on the R/B).
A reduction in floor loading is under consideration by using asuspension-bridge type structure that can release the load to theoutside.
The weight of the cells is supported by BSW and the anchorage
outside R/B.

• A method is under consideration to connect an extension
building built outside the R/B and the PCV with an accesstunnel.
• The access tunnel weight will be supported by the BSW and
the R/B wall at both ends, respectively, so that no additionalload is exerted on R/B 1st floor.

• The cells, transfer carriage, etc. are laid out on 1F of R/B.
• Equipment requiring maintenance and fuel debris aretransferred by the carriage to the external extension building.
• The equipment cell and the transfer carriage are laid out on
the main beam so that additional margin to the load capacityof the floor can be obtained. Our plan is to reduce the floor
loading by distributing the load with steel floor plates.

©International Research Institute for Nuclear Decommissioning

No.76

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improvement of work cell manageability by establishing work cell installation methods for top entry and side
entry and also by reducing the load on the reactor building Study concerning reduction of load to the reactor building• The action policy was set to meet the floor load restriction and issues were identified.
No.

1

Variations inside the
PCV access route andcorresponding cells
layoutStorage
Canister3

Action policy on cell installation
Wall

Wall
reinforcement

PillarExtension
Building

Use
existing
openings

Remove--RemoveYes-

Build new
openings-

Build new
openings

Carrying-in/out
of others thandebris

PLAN-A: Method boringa hole through R/B walls
and then reinforcing
boreholes
PLAN-C: Method withoutboring R/B walls

Issues

Notes

PCV

PLAN-B: Method boringa hole through R/B walls
but leaving pillars as
they areCask

2

Preparatory work for R/B internal structures

1. The load exerted on 1F of R/B needs tobe reduced as much as possible to securea margin for installation the systemequipment on R/B 1st floor.
2. For dose reduction for workers, an accesstunnel connects the extension building
and PCV by a cantilever structure.
3. No additional load shall be exerted on R/B
1F floor during installation work.
4. After installing the access tunnel, it needs
to be supported by the BSW and the R/Bwall at both ends, respectively, so that no
additional load is exerted on R/B 1st floor
R/B.

1. The feasibility of theconstruction of the accesstunnel in narrow areas on
the construction route.
2. Feasibility of achieving
accurate mating of theaccess tunnel front end to
the PCV opening.
3. Feasibility of heavy weight
object handling.
4. Feasibility of the sealing
method of the connection
between the access tunnel
and the PCV.

Details are being studied.
--©International Research Institute for Nuclear Decommissioning

No.77

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improvement of work cell manageability by establishing work cell installation methods for top entry and side
entry and also by reducing the load on the reactor building Study concerning reduction of load to the reactor building• The specific structure of the cell (access tunnel) was designed by incorporating measures for issues. In
addition, element tests are planned in the "project for upgrading of approach and systems for retrieval of fueldebris and internal structures" to assess the feasibility of the conceptual study results.

Access tunnel
carriage system

Access Tunnel

Access Tunnel

Access tunnel joints

PCV

Example for Unit1
Access tunnel total length: approx. 20 m
Access tunnel total mass: approx. 800
tons
Shield thickness: 300 mm
Material: carbon steel and others©International Research Institute for Nuclear Decommissioning

No.78

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cella. Improvement of work cell manageability by establishing work cell installation methods for
top entry and side entry and also by reducing the load on the reactor building Preparatory studies and work for buildings• The seismic resistance of R/B after installing facilities and equipment for fuel debris
retrieval is under consideration assuming both the side entry and the top entry
methods are used in combination.
• The assessment of the impact of openings constructed in the R/B wall and the PVC
wall on the earthquake strength of R/B is planned.
• The study of installation and fixing methods of the fuel debris retrieval cell is plannedwith consideration of floor load capacity.
• The study of the installation procedure of the fuel debris retrieval cell is planned withconsideration of R/B soundness .

©International Research Institute for Nuclear Decommissioning

No.79

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Study of methods for sealing between PCV and cell⚫

PCV

Main design specifications of cell adapter
Welding
methodOne side TIG fillet weld

Beveling

No (considering accessibility by torch)

Fillet weld

Main materials SM490B (welding part), SUS316, etc.

⚫

Cell adapter

Function

Sealability to maintain negative pressure

Inspection[Before welding] Gap check, [After welding] Appearance check, pressure
resistance and leak tests

Others･Seismic displacement is absorbed by bellows (displacement of 20 mm inboth horizontal and vertical direction is assumed)･Planning to adopt a double-bellows (thin plate) system for redundancy

X-6 penetration

Issues for sealing by welding➢

The feasibility of sealing by welding was verified by the welding test conducted (using a partial model) in FY2016.

[1] Remaining/predicted issues
Collect useful data on welding (review of welding conditions, techniques and equipment, methods of welded joint repair, handling of mill scales that are generated in
TIG welding on rare occasions, temporary fitting method, etc.)
Select and verify adequacy of a method to remove paint and rust on the PCV surface
Method to align beveled edges to be welded together in groove welding (remote-controlled beveling and the alignment of the beveled edges based on surface
measurement)
Feasibility of producing a metallic double bellows (thin plate) (assurance of redundancy, if there is an alternative mechanism, it will be studied as well)
Verify the soundness of the material used for the PCV (conducted on Unit1, including Estimate, by remote-control, the hardness measurement and examine materials
removed from the PCV by the opening boring)[2] Collect useful data concerning welding work (to be implemented when it becomes necessary in the course of discussion with regulatory authorities)[3] Verify selected welding methods using test samples that simulate actual structures (full-scale models) (including the verification of construction procedures, temporary
fitting methods, and the degree of deformation [that cannot be known in tests with samples])[4] Welder training* [2] & [3]: Enhance remote-controlled welding technique and screening of welders, [4]: Welder training©International Research Institute for Nuclear Decommissioning

No.807. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Study of methods for sealing between PCV and cell

⚫ Comparison of sealing methods
Comparative
item[A]: Advantage, [B]: Issues (for which testing is under preparation or ongoing for solution), [C]: Disadvantage or issues

Inflate seal (EPDM)

Weld

Sealability

 Flexibly fitting the undulation of a sealing surface that may be encountered in the actual work siteand providing a good seal performance* The seal material needs to be exchanged regularly by remote operation.

 Permanently sealed* The difficulty level of remote-controlled welding is high.

Difficultylevel of work
(including
remotecontrolledwork) Applicability to a sealing surface with irregular shape is relatively high.
[B] The preparation of remote-controlled sealing tests using actual size
workpiece samples is underway because the difficulty level of remotecontrolled sealing work is high.

 Since the difficulty level of remote-controlled welding is high, remote-controlled welding tests using partial models of
workpiece (welding bevel gap, 3D curved surface) were performed and the feasibility of the method was verified.
* It is necessary to establish the method for beveling the part to be welded that has a surface undulation according todata obtained by measuring the PCV surface as well as the method to align the beveled edges by remote operation.
* It is necessary to establish the method of repairing welded joints, and the method to take care of mill scales that are
generated in TIG welding, on rare occasions.
* The overall verification of the welding method using a full-scale model is necessary, including verification of atemporary fitting method and the impact assessment of deformation by welding.

Verificationandinspection*Under consideration

 Appearance inspection and leak inspection

Maintenanceandexchange[B] Periodic exchange. Preparing tests of the sealed surface, securing analternate boundary, and sealing exchange work is underway because of thehigh difficulty level of remote-controlled seal exchange work.

 Only basic monitoring

Seal
performance
deterioration

 Periodic exchange is required due to deterioration by radiation.
 Relative displacement caused by earthquake or other conditions can be absorbed by the flexibility,
and the inertial force is negligible.

 Relative displacement and inertial force caused by earthquake or the like can beabsorbed by the bellows.
 The deterioration of seal performance is not likely to occur because a corrosion margin
is incorporated in carbon steel in advance.

Abnormality
detection The deterioration of seal material can be detected by the monitoring of the inner pressure of the sealmaterial.
* Sealing performance can be monitored by the pressure of the boundary indirectly.

* Sealing performance can be monitored by the pressure of the boundary indirectly.

Restoration[B] The same procedure as seal material exchange applies. Preparation oftests that simulate work in the actual reactor is underway.

* Leaks can be fixed by spraying seal material, subject to the possibility to avoid
interference by debris removal equipment.

Waste

Generationof wastematerials* Waste materials are generated by changing seal material.

 Basically none

Record ofapplication

Nuclearfacilities

 It is typically used as a component of the boundary of cells constructed in reprocessing facilities* Only the record of small seal materials and not large seal materials as far as remote-controlled
exchange is concerned.

 Boundary construction by welding is general.
* The difficulty level of the alignment of beveled edges, temporary fitting and welding work of them by remote operation
is high.

Features

Workability

Maintainability

Response to
emergency/acc
ident©International Research Institute for Nuclear Decommissioning

No.81

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)⚫ Purpose of development➢➢

Establish methods and technologies to improve the sealability (sealing performance) of the connection between the
PCV and cells, which is essential to meet one of the highest priority requirements among all safety requirements, thatis, the "confinement of radioactive materials"
Establish methods and technologies to install and exchange seal material by remote operation✓ The following items will be included in the study concerning the construction of confinement boundary:• Improve the sealability of existing primary boundaries (such as those of the PCV)
Cell adapter• Seal design of newly constructed primary boundaries (such as those of cells)
Fillet weld
• Negative pressure control inside the primary boundary✓ The following methods have been studied for the sealing of the connection between cells and the PCV
until now.
• Sealing by welding (figure on the right)• Sealing by seal materials (such as organic seal materials)
Protective sheet⚫ Issues to be resolved

Shielding

It is necessary to verify that;➢ The applicability of the seal material to sealing the connection between the fuel debris retrieval work cell and PCV,
including durability for long-term use.
➢ The feasibility and safety of the remote-controlled operation to install and exchange the seal material.

©International Research Institute for Nuclear Decommissioning

No.82

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)⚫ Issues to be resolved
It is necessary to verify that;➢ The applicability of the seal material to sealing the connection between the fuel debris retrieval work
cell and PCV, including durability for long-term use.
➢ The feasibility and safety of the remote-controlled operation to install and exchange the seal material.

©International Research Institute for Nuclear Decommissioning

No.83

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval
equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflatesealing or water sealing)

Seal between BSW and PCV
Element Test
• Verification of performance
to seal part having a 3D
curved surface• Monitoring of the soundnessof the seal material during
operation⚫ Development approach➢➢

Development is conducted in multiple phases while
the applicability of seal materials is being examined.
✓ Phase 1: Applicability evaluation and testplanning through desk study and preliminary
tests✓ Phase 2: Applicability evaluation of sealmaterials by stand-alone element tests✓ Phase 3: Combination element tests using
M/U module
Before proceeding to the next phase, expert review
is provided⚫ Expected results➢➢➢

Select and evaluate seal material used to seal theconnection between the PCV and cells
Design specifications of the sealing structure using
seal material✓ Applicable range and other specs
Seal material installation and maintenanceprocedures (proposed)✓ Installation and maintenance procedures ofseal material that is applied to the sealing ofa 3D curved surface✓ Procedure to ensure an alternate boundary

until December 2017 (Phase 1)

1.5 m• A size covering an outerdimension of 2 m x 1.5 m• Metallic molding• EPDM

2m

Inflate seal

Test tool

Seal between BSW andPCVCombination tests

October-December 2018
(Phase 3)

PCV wall test mock-ups

Inflate seal

BSW mock-up• Remote-controlled
installation/dismantlement• Seal performance verification
Remote operation equipment(Manipulator)
Equipment
Transport Carriage

When sealing is
activated (inflated)

When passing through the©International Research Institutefor Nuclear
Decommissioning
BSW
opening(folded)No.84

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)⚫ Development goals➢ The maximum permissible leakage required for individual sealing parts, each of which is subjected todifferent differential pressures, shall be met for common sealing means to be employed in different
parts✓ The element test to examine performance to seal a part with a 3D curved surface needs to be
performed using a test tool specially made for this purpose.
➢ Remote-controlled installation/dismantlement✓ The sealing material needs to be foldable to clear the opening in BSW. It will be inflated during
sealing➢ An alternate boundary shall be prepared while maintaining the seal material to ensure workers’ safety⚫ Environmental conditions (examples):➢ Dose rate (1F R/B): 5-10 mSv/h
Dose rate (near PCV shell outer wall): 10-100 Sv/h-> Assume increase of dose rate to the level equal to inside PCV➢ Temperature: 0-40°C➢ Humidity: Same level as the atmosphere outside the facility* Specific values will be determined during the course of study.

©International Research Institute for Nuclear Decommissioning

No.85

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)⚫ Test and judgment conditions (examples)➢ Tests and subsequent judgment shall be made assuming that the PCV and BSW have 3D curved
surfaces based on drawings.
➢ Dimensions of BSW opening: 2 m x 1.5 m (tentative)➢ Leak tests shall be performed to confirm the following:✓ In the leak test by the pressure drop method, 50 percent of the initial additional pressure of
300Pa shall be maintained after a test period of 30 minutes.
✓ There shall not be continuous bubble generation, increased bubbling, or air eruption in the
bubble leak test.
➢ Remote-controlled installation and dismantlement✓ The seal material can be inserted to a depth of 100 mm (tentative) from the opening entrance✓ The sealing material can be removed from the sealing gap smoothly.
* Specific test values and judgment conditions will be determined during the course of study.

©International Research Institute for Nuclear Decommissioning

No.86

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(1) Functional Requirements⚫ The sealing means applied to connection parts is one of requisite elements to construct
the boundaries based on basic safety requirements. Thus, functions that the sealingmeans need to provide must be identified based on basic safety requirements.
➢ Confine radioactive materials by setting a boundary⚫ Safety requirements shall be met during sealing means installation, maintenance andexchange tasks.
➢ Worker exposure reduction©International Research Institute for Nuclear Decommissioning

No.87

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)

BSW

Primary boundary

PCV

Weld

(2) Means to meet functional requirements⚫

Construction of a boundary formed by the PCV, a cell and the connecting part(sealing part) between the PCV and the cell⚫

Maintaining the inside pressure of a boundary at a lower level than thesurrounding area to suppress radioactive material leakage to within apermissible level⚫

The following means shall be considered as candidates for sealing means:➢➢

Sealing by welding•

High reliability over a long period of time is expected•

Some parameters affecting the quality and performance of welding(such as a gap) need to be controlled within a narrow range, though it
can be difficult.
-> The feasibility of a remote-controlled welding method that canachieve the required sealing performance was proved by element
tests performed until last fiscal year

ShieldBellows

Weld(Element tests
completed)

Cell adapter

Cell

Example of sealing by welding

Primary boundary

Inflate seal
(generic type)

BSW

Mixture of mortar andcaulking material(generic type)

PCV

Sealing by seal material•

Sealing material is easier, and the applicable range is wider than weld
sealing•

There is an issue involving use over a long period of time sinceperiodic exchange is required.
-> The feasibility will be verified in this technical development

Both welding and seal material methods will be continuously studied inparallel since each method has its own issues, and it’s not possible to selectone of them at present.

Seal material(to be developed inthis program)

Cell

Shielding (sealing) door

Example of sealing by seal material©International Research Institute for Nuclear Decommissioning

No.88

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(3) Requirements⚫

In normal conditions, leakage at the seal part shall be 40 m 3/h or less.
➢This target is set based on the total area of unsealed apertures, with which a negative pressure targetof -100 Pa can be still maintained by the ventilation capacity of 1000 m 3/h.

➢Assuming that unsealed apertures spread on the surface of the primary boundary uniformly, the areaof unsealed apertures per unit surface area of the cell is set as the permissible area of unsealed
apertures at the sealing part.

➢

The amount of leakage that occurs when a target negative pressure is applied to the sealing part isused to define a target value since the area of unsealed apertures cannot be measured.

⚫

Differential pressure used for design: (to be determined) the soundness of the sealing part must be assured
against applied pressure difference.

⚫

Relative displacement: the soundness of the sealing part must be assured against a replacement of ± 5mm.
➢

This value is set based on an assumed relative displacement between the PCV and R/B inearthquake.

⚫

Sealability shall not be degraded (worse than a target leakage of 40 m3/h) by change in the shape of the sealmaterial.

⚫

Material resistant to deterioration over time shall be used for the seal material.

⚫

The sealed part is subject to periodical maintenance (inspection and replacement).

⚫

The seal abnormality should be detectable during fuel debris retrieval.

⚫

Means to maintain the confinement performance of the primary boundary shall be provided during
maintenance.

⚫

Reduce workers exposure during installation and operation (maintenance) of sealing means.
©International Research Institute for Nuclear Decommissioning

No.89

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(4) Issues and countermeasures for basic functions
Basic functions
Leakage at sealed part: 40 m 3/h or lessIssuesMeasures

Capability to seal part having a 3D curved surface

Verified by element test (unit test)

Sealing without a guide groove for seal material

Verified by element test (unit test)

Sealing of part having a gap made by welding, etc.

Verified by element test (unit test)

Differential pressure used for design: (to be
determined) the soundness of the sealing part must
be assured against applied pressure difference.

Same as above

Verified by element test (unit test)

Relative displacement: the soundness of the sealing
part must be assured against a replacement of ±5mm.

Same as above

Verified by element test (unit test)

Sealability shall not be degraded (worse than atarget leakage of 40 m3/h) by change in the shapeof the seal material.

⚫ Same as above⚫ Provision of sealing performance in case of lost
inflation pressure of the seal material

Verified by element test (unit test)

Material resistant to deterioration over time shall be
used for the seal material.
The sealed part is subject to periodical maintenance(inspection and replacement).

Notes
Already verified byfundamental test as well

Already verified byfundamental test as well

EPDM is adopted⚫ Feasibility of remote-controlled tasks⚫ Flexibility of the sealing means to cope with variationin the condition of the sealing part

⚫ The influence of maintenance on throughput needs tobe reduced.
The seal abnormality should be detectable during
fuel debris retrieval.

Procedures of remote-controlled exchange work andthe sealability of the seal material installed by theremote operation will be examined by element tests(combination element tests)

Monitoring of the inner pressure of seal material

Means to maintain the confinement performance ofthe primary boundary shall be provided during
maintenance.

⚫ Sealability of boundary during temporary closure

Feasibility is confirmed by desk study
Needs to be examined in the course of study

Reduce workers exposure during installation andoperation (maintenance) of sealing means.

Dose reduction for workers during recovery andrestoration

If intervention by workers is necessary, each worker
time in high radiation areas must be measured toassess exposure levels.©International Research Institute for Nuclear Decommissioning

No.907. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(5) Select and evaluate materials used for the inflate seal

EPDM (Ethylene Propylene Diene Monomer, popularly called as ethylene-propylene rubber) was selected as the material of the inflate seal.
EPDM has high radiation resistance along with other suitable properties, such as heat resistance and resistance to hot water. Due to its wellbalanced properties, there are records of applications in nuclear facilities.
Although urethane rubber has similar radiation resistance to EDPM, it is inferior to EDPM in heat resistance and resistance to hot water.
There is data indicating EPDM’s radiation resistance is as high as 106 [Gy]. Based on this date, the durability of EPDM under 100 Sv/h isapprox. one year and two months.

Sealability

Workability

Ethylene-propylene
Urethane rubber
rubber EPDM
[A]
Not Applicable
Widely used as generic It is widely used asseal material.
generic seal
Superior in hot water
material. However,resistance.
resistance to heat,water and humidity
is low.
[A][A]
Widely used andWidely used andsuperior in workability superior inworkability

Fluoro-rubber

Silicon rubber[A]
Widely used as
generic sealmaterial.
Superior in hot
water resistance.

Not Applicable
Widely used as
generic sealmaterial. However, it
is inferior inresistance to gas
permeation.
[A]
Widely used andsuperior inworkability[A]
Widely used andsuperior inworkability

Acrylic rubber
Butyl rubber
Ethylene-propylene rubber
Fluoro-rubber
Chlorosulfonated polyethylene
Natural rubber
Chloroprene rubber
Nitrile rubber

Polysulfide rubber[S]
Urethane rubber[A]
Widely used in
Not Applicable
Actual
It
is
used
under
nuclearfacilities
with
Silicon rubber
Use in nuclear
Schedule
radiationa
proventrack
Styrene-butadiene rubber
facility is relatively
environment with a record.
rare.
proven track record.
[S][S]
Somewhat
Somewhat
Minor
Superior in radiation
Superior in radiation Applicable
Applicable
Radiation
resistance compared to resistance
It is inferior to
It is inferior to EPDM
Mild
resistanceother rubber materials. compared to other EPDM andand urethane
Severerubber materials.
urethane rubber.
rubber.
Cited from "Polymeric Materials for Atomic Power Industry" published by Japan Atomic Energy Research InstituteSomewhat
http://jolissrch-inter.tokai-sc.jaea.go.jp/pdfdata/JAERI-M-9412.pdf
Total evaluation [S]Not Applicable
Not Applicable
Applicable[S] Excellent, [A] Good, [B] Acceptable[S]
Widely used underradiation environment
with a proven trackrecord.

©International Research Institute for Nuclear Decommissioning

No.91

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(6) Study of circumference shape of sealing partThe circumference shape of the inflate seal’s sealing part shall be in a rectangular shape that fits the BSM
opening in consideration of the easiness of installation by remote operation.
1800

1624 (effective opening width)* Dimensions are tentative and shown for reference purpose only.
PCV Wall2244 (effective opening height)

BSW

PCV Wall

2500

R=200

BSW opening

PCV opening

75
Inflate seal
©International Research Institute for Nuclear Decommissioning

No.92

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(7) Selection of the cross-section shape of sealing part
Shapes of the cross-sectional shape of sealing part were narrowed down to rectangular and rhombic using a inflate seal material as the resultof the following evaluation items.
Further study of the cross-sectional shape of sealing part will be conducted by putting weight on a rhombic shape. Self-sustained recovery inan emergency and sealability is highly likely.
Evaluation of cross-section shapes
Diamond
Mound-shaped

Rectangular
Fixation wall surface

Lip-shaped

Fixation wall surface

Evaluation item
Fixation wall surface
Fixation wall surface
Insertion direction
Insertion direction

Sealability

Gap between BSW and PCV(width of approx. 50 mm, 3D
spherical surface)

[A]

[A]

[A]

[B] Less flexibility and ability to fit
with a given shape

Absorption of displacement
caused by thermal expansion orearthquake

[A]

[A]

[A]

[B] Less flexibility and ability to fit
with a given shape

Crossing with bumpy weld linesof the PCV
Remote-controlled handling
Handling ability (carrying-in, installation andreplacement)[B] Leakage risk involved.

[A]

Somewhat Applicable The sealmaterial cannot retain its proper
Consideration Consideration of ability in trouble position.
Somewhat Applicable Leakage
of ability in(when the inflation pressure isoccurs because it cannot seal
troublelost)
contacting surface with sufficientpressure.

Total evaluation

Somewhat Applicable[B] Leakage risk involved.

[C] Leakage due to small [C] Leakage due to small contact
face.
contact face.

Good 〇: applying negative
C: Low foldability
pressure and inserting into
[B] Friction during insertion
the position[A]The
position can be retained.
Somewhat Applicable Leakage
suppression can be expected
due to contact surface pressure.

[B] Lip caught

[A]
The
[A]
The
position can be retained.
position can be retained.
Somewhat Applicable Leakage Somewhat Applicable Leakage
suppression can be expected due suppression can be expected due
to contact surface pressure.
to contact surface pressure.
A: Good[B] Poor
C: Low feasibility[A]

Not Applicable

Not Applicable©International Research Institute for Nuclear Decommissioning

No.93

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(8) Procedures of the remote-controlled installation of the inflate seal
Sealing/shielding
door

Equipment
Cell

Drywell manipulator<Step 1: preparation for installation>• Boring of BSW, installation of the equipment cell, andinstallation of the drywell manipulator need to be finished sothat installation of the inflate seal can be started anytime.
• It needs to be confirmed in advance that there is no object
blocking installation of the inflate seal between BSW and
PCV. If there is, the object needs to be removed by thedrywell manipulator.
Gripper

Inflate seal grip

Carrying plate

Inflate seal

Drywell manipulator

Carrying plate

Inflate seal

<Step 2: carriage of the inflate seal>• Carry the carrying plate the inflate seal is attached to by
the drywell manipulator.

Gripper

Inflate seal grip

<Step 4: installation of the inflate seal>• Grasp pre-installed grips of the inflate seal by the gripper and move them to positions predetermined for eachgrip one at a time. Here, magnets are attached to the inflate seal adjacent to each grip so that the inflate seal
can be installed in the predetermined position.
• Check the position of the inflate seal by visual inspection and/or dimension measurement to make sure it has
been installed in the right position.
• Connect an air supply tube to the inflate seal and inflate it with air.

<Step 3: placement of the carrying plate>• Mount the carrying plate on the PCV wall. Fix thecarrying plate on the PCV wall by magnets that wereattached to the backside of the plate in advance.

Carrying plate

Inflate seal

<Step 5: Carrying-out of the carrying plate>• Move the carrying plate with the drywell manipulator out
of R/B.

©International Research Institute for Nuclear Decommissioning

No.94

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(9) Unit test plan
[Seal material production]• Metallic molding• EPDM• Provided with bosses for interface

Test procedures and criteria

Pressure
indicator
Temperature
measurement
Pressure
indicator

Inflate seal*

Test tool
Check item

Test parameters
Seal material
inner pressure
[MPa]
0
0
0.03
0.08
0
0.03
0.08
0
0.03
0.08

Gap width [mm]
50
55
55
55
50
50
50
50
50
50

Weld line
simulant bump
No
No
No
No
Yes (Height: 3 mm)
Yes (Height: 3 mm)
Yes (Height: 3 mm)
Yes (Height: 1 mm)
Yes (Height: 1 mm)
Yes (Height: 1 mm)[Test procedure][1] Attach the test facility to a test tool, sandwich them with two curved
plates, and narrow the gap between the plates to a predetermined width.
[2] Inflate the seal material with pressurized air.
[3] Increase the inner pressure of the closed space formed by the sealmaterial and the test tool to a predetermined seal pressure*.
[4] Evaluate ability to fit with a given shape and sealability.
[5] Maintain the seal pressure and measure leakage.
[6] Measure the displacement in the direction of the line perpendicular tothe sealing part circumference.
[7] Stand the test facility with the test tool up straight and check whether
it stays in the right sealing position.

The seal pressure is set at 300 Pa based on the designed
differential pressure plus margin. In addition, the seal pressure isincreased up to 500 Pa gradually, and leakage is measured to
examine the maximum sealing performance.
Criteria

Ability to fit with a given shape

No aperture in the contacting surface

Sealability(bubble leak)

No continuous bubble generation, no increased
bubbling, nor air eruption

Leakage measurement

Leakage at the differential pressure in actual use,which is calculated with test data, shall be equal
to or less than the maximum permissible leakage.

Retention of sealing position

The test facility shall stay in the right sealing
position when the test facility with the test tool isstood up straight.
No abnormal deformation in its circumference
shape of sealing part

Circumference shape of sealingpart(It is assumed to change its
shape from rectangular to roundas being inflated)©International Research Institute for Nuclear Decommissioning

No.95

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)(10) Plan of combination tests

Check item and procedure
Criteria
Attach the inflate seal to the
The inflate seal shall be installed ininstallation tool and grasp the tool by the right position. The inflate seal
the manipulator.
shall be grasped by the manipulator.

Test procedures and criteria• Remote-controlled installation/dismantlement• Seal performance verification

PCV wall test mockups
BSW test
facility

Inflate seal

Remote operationequipment (Manipulator)

Equipment
Transport Carriage

When sealing is
activated (inflated)

Carry in the inflate seal through the
BSW opening

Insert the inflate seal into the gap and The inflate seal shall be inserted into
fix itthe gap at a predetermined depth.
The position of the inflate seal shallbe fixed.
Increase the inner pressure of the
There shall not be continuous bubble
inflate seal and then verify sealability generation, increased bubbling, or(bubble leak test)
air eruption.
Leakage measurement

When passing through the BSW
opening (folded)

The inflate seal shall clear the BSW
opening without interference.

Removal of the inflate seal from the
gap

Leakage with a constant testingpressure of 300 Pa for the sealed
space shall be equal to, or less than,the maximum permissible leakage.
The inflate seal shall be removed
from the gap smoothly.

Carry out the inflate seal through the The inflate seal shall clear the BSW
BSW opening.
opening without interference.
Inflate seal exchange procedure

The inflate seal exchange procedure
shall be feasible.

©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.96

7.2. Implementation Details2) Element technology development for installing retrieval equipment[1] Element technology development related to work cellb. Work cell sealing method (such as welding, inflate sealing or water sealing)
FY2017 (Heisei 29)

Items to study
4

Key milestones
a. Conceptual study/test plan

5

6

7

8

9

Phase 1: Desk study
Preliminary tests

10

11

Plan

FY2018 (Heisei 30)
12

1

2

3

4

5

6

7

8

9

10

11

12

1

2

Decision for starting test
production of devices

Element Test

1. test device design

2. test device planning

Phase 2: Element tests

b. Test preparation/test device
test production
c. Element Test

1. Unit test
2. Improvement

Phase 3:
Combination tests

3. Combination tests
Summary

Notes

Expected results[1] Select and evaluate seal material used to seal the connection between the PCV and cells[2] Design specifications of the sealing structure using seal material⚫ Applicable range and other specs[3] Seal material installation and maintenance procedures (proposed)⚫ Installation and maintenance procedures of seal material that is applied to the sealing of a 3D curved
surface⚫ Procedure to ensure an alternate boundary©International Research Institute for Nuclear Decommissioning3

No.97

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system[2] Development of a fuel debris cutting/dust collection system[3] Development of methods to prevent fuel debris diffusion

2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell[2] Technical development for removing interfering objects during fuel debris retrieval

3) Development of remote maintenance technologies for fuel debris retrieval equipment
4) R&D management©International Research Institute for Nuclear Decommissioning

No.98

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
Development of remote technologies necessary to realize the dismantlement, removal, collection,and carrying-out of debris and element tests are planned; there are interfering objects on theaccess route to fuel debris whether the side entry or the top entry methods are chosen; the removalof those interfering objects is a challenge for successful fuel debris retrieval; basically, thoseinterfering objects need to be removed remotely. The following things are considered in the plan:• Interfering objects that block access from top entry: PCV upper structures (such as well shield
plug, PCV head and RPV head), reactor pressure vessel (RPV) internals (such as dryer andseparator)• Interfering objects that block access from side entry: Equipment outside the pedestal• Interfering objects that block both top entry and side entry: equipment inside the pedestal (CRD
housing. etc.), R/B internals (contaminated instrumentation guide tubes, high radiation pipes,etc.)*1
Note that newly identified issues in studying access routes, such as the removal of obstacles, will
be addressed without exception and measures for them will be studied.
*1:

The study of removal methods for R/B internals (contaminated instrumentation guide tubes, high radiation
pipes, etc.), will be conducted only on structures that will apparently block fuel debris retrieval work.

©International Research Institute for Nuclear Decommissioning

No.99

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval⚫ Purpose of development➢ Verify feasibility of methods for removing interfering objects (including fuel debris adhered tothem) that block access to fuel debris⚫ Issues to be resolved➢ Feasibility of remote work
✓ Removal procedures and methods✓ Fall prevention✓ Cabling and task monitoring method✓ Method to carry out removed objects➢ Selection of processing tools✓ Applicability of processing tools for removal work
✓ Measures to prevent the dispersion of dust generated by the PCV opening boring©International Research Institute for Nuclear DecommissioningNo.100

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval⚫ Development approach
➢
➢
➢

➢

Identification of interfering objects that need to be removed
Study of interfering object processing methods
Element test planInterfering objects are picked up, and element tests are conducted with them to evaluate the possibility ofremoval work
✓ Method to remove interfering objects by fuel debris retrieval equipment by the top entry method(The the side entry method is also taken into account)• Methods to remove structures in RPV bottom part (including CRD housing)✓ Methods for removing interfering objects by fuel debris retrieval equipment using the side entry method• Means and method to remove interfering objects (pipes and supports) outside Pedestal• Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside✓ Method for removing interfering objects by fuel debris retrieval equipment commonly used in accessfrom both entries• Means and methods for removing interfering objects inside the pedestal• Verifying maneuverability by a combination of a robot arm and access rail
Feasibility verification by elemental tests⚫ Expected results➢➢➢

Feasibility of processing methods used for removing interfering objects
Feasibility of the PCV opening construction methods
Calculation of throughput using each work time

©International Research Institute for Nuclear DecommissioningNo.101

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval

The following conceptual study and element tests are planned:
It was decided to the conduct element tests focusing on the technology development of the side entry method for fuel debris
retrieval, following the decision about the debris retrieval policy by the Ministry of Economy, Trade and Industry and the Agency
for Natural Resources and Energy.
Common• Interfering objects that need to be removed to clear the access route to fuel debris were identified for all possible accessmethods and the applicability of various processing methods was studied. In addition, a conceptual study on thethroughput of obstacles removal work is being implemented.
a. Method to remove interfering objects by fuel debris retrieval equipment by the top entry method• A conceptual study and element tests concerning methods of removing interfering objects in the RPV bottom part areplanned for the following reasons: in the RPV bottom part, molten fuel debris and metal structures mixed together andsolidified to form objects that are very difficult to process; and measures to prevent the fall of equipment laid out in thereactor bottom, such as CRDs and the CRD housing during removal work, will be difficult compared to other structures
since those equipment will lose support and fall*1 when they are cut from the RPV side.
b. Methods for removing interfering objects by fuel debris retrieval equipment using the side entry method• According to the policy to put weight on the side entry method, study and relevant element tests concerning specificmethods for removing interfering objects that block the access route to fuel debris in and outside the pedestal areplanned mainly from the priority viewpoint.

c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access from both
entries• Element tests concerning the removal of fallen objects, such as CRD, are planned with regard to interfering objects in thepedestal.
• Element tests concerning the maneuverability of a robot arm and access rail combined mechanism are planned.
• A conceptual study of removal methods that combines the top entry and the side entry methods is planned.
*1: It is assume the result of the PCV inside investigation conducted on Unit3 that CRD support structures d by are not working.
©International Research Institute for Nuclear DecommissioningNo.102

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
A conceptual study on the method for estimating the throughput of interfering object removing work is
being implemented.
➢ Simplification of structures
Complex structures are simplified to estimate a rough time period for interfering
object dismantlement.

Example ofsimplified structure

Sample of a grating
support structure

Simplification of structure, constant plate thickness, etc.
➢

Use of a fixed cutting speed
Only one severing method is assumed to eliminate the influence of the type of a severing method on the time
period estimation.
Table 6.1.2-1 Variation of plate cutting speed with the plate thickness and the type of cutting methods
Plate thickness
(mm)

Laser
(mm/min)Plasma arc (mm/min)

AWJ(mm/min)

Wire saw (m2/h)

5 or less

3,000

900

300

0.05

6-35

250

400

70

0.05

36-150

40

60

15

0.05

The cutting speed data is cited from the JAEA technical report "The Selection of the Cutting
Technologies for Removing the Fugen Reactor".

⚫

Cutting speed of disc cutter (actual measurement by IRID)[86 mm/min] when cutting a plate whose thickness is up to 230 mm©International Research Institute for Nuclear DecommissioningNo.103

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval➢ Temporary preconditions concerning the collection and handling of interfering objects are set in thetable below to estimate the throughput of interfering objects removing work.
No.

Items

Temporary preconditions

Notes

1

Number of work days for interfering
object dismantlement per year

200 day (Remaining days are used for maintenance)

2

Daily work hours for interfering
object processing

Within 24 hours

3

Amount of interfering objects

The amount of interfering object that need to be removed to start the fuel debris retrieval is being
studied for each plan of the side entry method.

4Interfering object processing tools

1.
2.
3.

Follow the "Cutting procedures for removing FUGEN reactor" by JAEA.
Disc cutter
Processing tools applicable to the RPV bottom part (CRD housing), biological shielding wall,
pipes and support structures outside the pedestal, and pedestal internals are selected by theelement tests of this project.

5Interfering object processing speed

1.
2.
3.

Follow the "Cutting procedures for removing FUGEN reactor" by JAEA.
Disc cutter: [86 mm/min] when cutting a plate whose thickness is up to 230 mm
Processing speeds of the RPV bottom part (CRD housing), biological shielding wall, pipes
and support structures outside the pedestal, and the pedestal internals are calculated using
data obtained in the element tests of this project.

6

Method to collect processedinterfering object

The speed of collection work is being estimated based on the use of collection methods with asolid track record, such as grasping and scooping.

7

Dimensions of processed interfering
object collection can

1.

2.
8

Interfering object handling speed

It was assumed that the maximum gross weight of a fully loaded collection can is 100 kg(equivalent to a cubic iron block with a 230 mm side length) to be able to be handled by amanipulator arm.
Dimensions are being studied within the range that can clear the PCV opening for each planof the side entry method.

Interfering object handling speed is being estimated based on the use of handling methods with asolid track record.
©International Research Institute for Nuclear DecommissioningNo.104

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval➢

Examples ofprocessing tools

A projected output image of the throughput of interfering objects removing work as of theend of FY2018 is shown below.
: interfering objects removing tests are planned.

: Interfering object
removing range

No.

Interfering objects

Type

Total
weigh
t (ton)NecessityofremovalRemoval period
Core boring

AWJ

Disc cutter

Need to be studied by the team responsible for the building

1

R/B wall

Waste

[A]

2

Shield plug

Waste

[A]

xx daysxx daysxx days3

Equipment Hatch

Waste

[A]

xx daysxx daysxx days4Interfering objects outside thepedestal(HVH, stairs, stages, etc.)

Waste

[A]

xx daysxx daysxx days5

CRD rail

Waste

[A]

xx daysxx daysxx days6

Grating

Fuel Debris*1[A]

xx daysxx daysxx days7

Grating support structure

Fuel Debris*1[A]

xx daysxx daysxx days

8

CRD, etc. (fallen objects)

Fuel Debris*1[A]

xx daysxx daysxx days

9

CRD exchange system

Fuel Debris*1

9[A]

xx daysxx daysxx days

10

CRD housing

Fuel Debris*1

6[A]

xx daysxx daysxx days

Total:

xxx daysxxx daysxxx days*1:While these are treated as fuel debris, their processing speed is estimated by taking the project element tests into account.
©International Research Institute for Nuclear DecommissioningNo.105

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval

A conceptual study on the method to estimate the throughput of fuel debris retrieval work by the side entry

method is being implemented.
: fuel debris retrieval work areas in the side entry method
PCV head

Position of
distribution

No.

Shield plug
RPV insulationmaterial

RPV head

Mass [t]Characteristics

Fuel rod stubs
RPV core
Powdery,
GrainedShroud head2

Powdery,
GrainedUpper grid plate

RPV
core

RPV bottom part

RPV bottom part

Almost all the fuel melted down, and The top part of fuel assemblies in the reactor
some undamaged fuel assemblies
core periphery melted down, and a few fuelremain in the reactor core periphery. pellets remain there(MAAP)

Inside the pedestal

3

CRD/
instrumentation
guide tube

4

Powdery,
GrainedInside Pedestal

5

Powdery,
GrainedOutsidePedestal
Lumps form

4 m or less

UO2, ZrO2,(U,Zr)O2, Zr(O)0-31
A few μm - a
few cmBoth the MAAP and the SAMPSON
code indicate small amounts ofdebris in the lower plenum

Molten core materials are rapidly cooled down
into small pieces

A few μm - a
few cmSlowly cooled to form lumps

Thickness
A few dozen
cm(U,Zr)O2(Zr,U)O2

Thickness
0.1-1 m(U,Zr)O2,(Zr,U)O2
Zr(O),Fe

Penetration
depth
10 and a few
cm(U,Zr)O2,(Zr,U)O2, SUS

Debris formed by mixed and solidified molten
metals and oxide fuelDebris adhered in gaps inside andon the outer surface of tubes

Debris clogged the flow passage of the lower
SUS tubes from the top end of the pressure
vessel

Because of early water injection,
most of the molten debris solidified
without forming MCCI
There may be MCCI is in the sumppit

Molten reactor core materials leaked out of RPV,
dispersed, and quenched
Shows little reaction with concrete

Lumps form

Outside thepedestalComposition

Molten core materials are rapidly cooled down
into small pieces

Lumps form

PipingSize

Adhered to or stacked on residual
structures

Crust(bedrock)

CRD instrumentation
guide tube

Debris properties

Features
MAAP

1Steam dryer

General state

Solidified debris leaked from thepedestal
Most is powdery or grainy

21-79

A few μm - a
few cm(U,Zr)O2(Zr,U)O2(U,Zr)O2(Zr,U)O2

UO2, Zr(O)(U,Zr)O2, Fe

92-277
Solidified debris in lump form is distributed
uniformly
There may be MCCI in the sump pit

Thickness 15
cm

Grainy debris has leaked from the pedestal

50 μm - 20cm

UO2, Zr(O)(U,Zr)O2, Fe

Penetration
depth
0.20 m or less

UO2, Zr(O)(U,Zr)O2, Fe(U,Zr)SiO2

Corium leaked from the pedestal reacted withthe concrete and solidified
Slightly rich in metal component

0-146

UO2, Zr(O)(U,Zr)O2, Fe(U,Zr)SiO2©International Research Institute for Nuclear DecommissioningNo.106

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
Temporary preconditions for fuel debris retrieval in the side entry method are set in the table below.
No.

Item

Temporary preconditions

Notes

1

Target time period for fuel debris
retrieval work

Unit1: 10 years, Unit2: 10 years, Unit3: 10 years

2

Number of work days for fuel debris
retrieval in a year

200 day (Remaining days are used for maintenance)

3

Daily work hours for fuel debris
processing

Within 10 hours

4

Amount of fuel debris to be removed

Assumed Unit3, which is the largest amount. (attached to CRD/instrumentation guide tubes: 6 tons*,
inside Pedestal: max. 277 tons, outside Pedestal: max. 146 tons, total: 429 tons)

5

Fuel debris processing tool

1.
2.
3.

MCCI: chisel processing, ultrasonic core boring, etc.
Attached to CRD/instrumentation guide tubes: disc cutter, AWJ, laser, etc.
Attached to metallic structure: disc cutter, AWJ, laser, etc.

6

Fuel debris processing speed

1.

Chisel processing, ultrasonic core boring: determined based on the element test results of thisproject
Disc cutter, AWJ, laser: similar processing speeds to those for interfering objects.
Core boring: 3.25 kg/h (test result in FY2016)
Laser gouging: 4.76 kg/h (test result in FY2016)

2.
3.
4.
7

Fuel debris retrieval method

A tentative collection speed is being estimated based on collection methods with a solid track record,such as suctioning, grasping, and scooping.

8

Fuel debris canister size⌀200 mm as a basic diameter, ⌀400 mm is also considered as an alternative.

9

Fuel debris handling speed

A tentative handling speed is being estimated based on handling methods with a solid track record.

*1: according to the result of the investigation in FY2015 by the Reactor Internal Condition Investigation Project©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1077.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
A projected output image of the throughput of fuel debris retrieval work by the side entry method as

Examples ofprocessing toolsof the end of FY2018 is shown below.
Waste

Total weight
[ton]

Type

PCV head
Shield plug
RPV insulationmaterial

RPV head

Steam dryer
Shroud headUpper gridplate
RPV coreRPVbottomInside thepedestal

Outside thepedestal*1: Although wastes on the upper grid and below areclassified as fuel debris, processing speed data obtainedby the interfering object dismantlement element tests ofthis project is considered to estimate the time periodrequired to remove these wastes.

Necessity ofremovalNot
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable
Not
Applicable

Removal period
Chiselprocessing

Disc cutter

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

xx days(x.x years)

AWJ

Shield plug

Solid radioactive waste465

PCV head

Solid radioactive waste

48

RPV insulation material

Solid radioactive waste

13

RPV head

Solid radioactive waste

66

Steam dryer

Solid radioactive waste

31

Shroud head

Solid radioactive waste

48

Upper grid plate

Fuel Debris

7

ShroudFuel Debris

46

Jet pump

Fuel Debris

12

Fuel debris in the reactor core

Fuel Debris

31

Fuel debris in RPV bottom

Fuel Debris

79Core support plate

Fuel Debris

11

Fuel debris attached to the RPV
bottom head and CRD housing
Wastes generated by the PCV
opening boring
Pedestal internals
CRD exchange trolley

Fuel debris*1

6[A]

Solid radioactive waste

40

[A]

Fuel debris
Fuel debris*1

90
9

[A]

*1

277

[A]

30

[A]

xx daysxx daysxx days[A]

xxxx days(x.x years)

xxxx days(x.x years)

xxxx days(x.x years)

xxxx days(x.x years)

xxxx days(x.x years)

xxxx days(x.x years)*1

Fuel Debris inside Pedestal

Fuel debris

Structures outside Pedestal

Solid radioactive waste

Fuel Debris outside Pedestal

Fuel Debris
Total time period

146

[A]

xx days(x.x years)

Core boring: xx days
xxxx days(x.x years)

xxxx days(x.x years)

xxxx days(x.x years)©International Research Institute for Nuclear DecommissioningNo.108

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method for removing interfering objects with fuel debris retrieval equipment by the top entry method
Interfering objects that need to be removed (including reactor internals) were identified and listed.

Note: A difficulty level is determined by relative evaluation
No.

1

2

3

Interfering objects

Shield plug

DSP slot plug

PCV head

General specifications(m)

Suggested
processing
methods(i) Main material
Concrete(ii) Main dimensions⌀12.5  H0.6 (top)⌀12.1  H0.6 (middle)⌀11.8  H0.6 (bottom)

Wire saw(push stroke),
Disk saw(i) Main material
Concrete(ii) Main dimensions
H6.3  W5.6  L2.1

Wire saw(push stroke),
Disk saw(i) Main materialSS(ii) Main dimensions⌀10.0  H4.5
(including handrail)

Disc saw, cutter (forplatform, etc.)
Disc saw, disc cutter,
AWJ (PCV)

Example of removing method(i) Detach from the reactor well and move tothe processing platform, cut into small
pieces, and remove.
(ii) Repeat the process [1] above for each partof the shield plug in the order of top,
middle and bottom.

(i) Install the processing equipment on theDSP.
(ii) Cut the plug by a wire saw (push stroke),collect cut pieces in a can and transfer
them out.
(iii) Use other methods for the edge andresidual small blocks where necessary andremove.

(i) Cut the platform, handrails, etc. into small
pieces by the processing equipment andremove.
(ii) Cut the PCV head into pieces of apredetermined size by the processing
equipment and remove.

RemoveDifficulty level

Low

Notes

• Removal methods that cancope with the degree ofdamage and the plan of
SFP fuel removal need to
be studied.

• Mockup tests wereconducted in thegovernment R&D project in
FY2016.

Low

Low©International Research Institute for Nuclear DecommissioningNo.109

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method for removing interfering objects with fuel debris retrieval equipment by the top entry method
Interfering objects that need to be removed (including reactor internals) were identified and listed.

Note: A difficulty level is determined by relative evaluation

No.

4

5

Interfering objects

Reactor thermal
insulation material

RPV head

General specifications(m)

Suggested
processing
methods

Example of removing method(i) Main materialSS(ii) Main dimensions⌀6.2  H3.8
(including handrail)

Disc saw, disc cutter,saber saw(i) Remove thermal insulation material on thetop, then cut the frame into pieces, andremove all of them.
(ii) Remove thermal insulation material at thebottom, then cut the frame into pieces, andremove all of them.

(i) Main material
Low-alloy steel(ii) Main dimensions⌀5.5  H2.9

Disc cutter, AWJ

RemoveDifficulty
level

Notes

Low

(i) Cut RPV nozzles and create openings.
(ii) Cut the RPV head into small pieces using
the openings created in the above as
cutting start points.
Medium6Dryer(i) Main materialSUS(ii) Main dimensions⌀4.7  H5.0

Disc cutter, saber
saw, AWJ(i) Cut the whole part of the dryer unit into
pieces sequentially from the top to thebottom, and remove all cut pieces.
(ii) After removing the dryer, cut the dryer
support skirt into pieces and remove.

Medium©International Research Institute for Nuclear DecommissioningNo.110

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method for removing interfering objects with fuel debris retrieval equipment by the top entry method
Interfering objects that need to be removed (including reactor internals) were identified and listed.

: Element tests underplanning

Note: A difficulty level is determined by relative evaluation

No.

7

8

9

Interfering objects

Separator

RPV core

RPV bottom part

General specifications(m)[1] Main material
SUS[2] Main dimensions⌀4.5  H4.6

Suggested
processing methods

Example of removing method

Disc cutter, sabre saw,
AWJ

[1] Cut the whole part of the separator unit into
pieces sequentially, from the top to thebottom, and remove all cut pieces.
[2] After removing the separator, cut the
shroud head into pieces and dismantle it.

[1] Main material
SUS[2] Main dimensions⌀4.8  H7.4
(reactor core structures)

Disc cutter, milling,
AWJ, laser[1] Main material
Low-alloy steel/SUS[2] Main dimensions⌀4.8  H6.7
(CRD housing, RPV
bottom reflection mirror,
etc.)

Disc cutter, grinding(milling), AWJ, laser[1] Cut the structure sitting in the reactor core
into pieces sequentially, from the top to
the bottom, using different tools depending
on molten or damaged condition of thestructure.

[1] Cut or crush fallen structure and fuel debris
into small pieces sequentially from the top
to the bottom and remove.
[2] Cut the CRD housing and structures
around it into pieces in sequential
procedures that incorporate work from thepedestal side effectively.

RemoveDifficulty
level

Notes

Medium･May have been deformed bymelting.

High

High

• May have been deformedby melting.
• Measures to prevent the fallof the CRD housing are
difficult.
• The CRD housing is highly
relevant to the side entry
method.

©International Research Institute for Nuclear DecommissioningNo.111

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method to remove interfering objects by fuel debris retrieval equipment by the top entry method
According to the decision on removal policy, element tests for removing interfering objects in the RPV bottom
part are planned because this work is highly relevant to the side entry method, and its difficulty level is high sincemeasures to prevent the fall of structures need to be taken during removing work.
⚫

Purpose of development➢ Feasibility verification of workability in a narrow space➢ Feasibility verification of a processing method taking fall prevention into account.
➢ Feasibility verification of workability by the top entry method, the side entry method, or a combination ofthem⚫

Issues to be resolved➢ Remote controlled workability➢ Processing method for narrow parts➢ Removing methods that take measures to prevent the CRD housing from falling into account⚫

Expected results➢ Feasibility of processing method for narrow parts➢ Feasibility of processing method taking into account fall prevention➢ Feasibility verification of workability by the top entry method, the side entry method, or a combination ofthem➢ Throughput calculation.

©International Research Institute for Nuclear DecommissioningNo.112

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method to remove interfering objects by fuel debris retrieval equipment by the top entry method
Schematic illustrations of element tests for removing interfering objects in the RPV bottom are shown below.
: Element test simulation
range
CRD housing flange

Fractured portion

ICM housing

CRD housing

to the RPV center

CR
guide
tube

The possibility of duplicating thefallen CRD housing and thefractured portion is being
examined, referring to the resultsof the inside investigation on
Unit3 PCV.

Test facility(Using existing facility)

Schematic illustration of interfering
objects in the RPV bottom

Schematic illustrations of element tests for removing
interfering objects in the RPV bottom(The test facility was prepared by modifying part of facility
constructed in FY2016)

Photo of Unit3
internal investigation

Image of test
mock-ups

To verify workability in a narrow
space, removing tests forinterfering objects are planned
using nine test mock-ups.

©International Research Institute for Nuclear DecommissioningNo.113

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method to remove interfering objects by fuel debris retrieval equipment by the top entry method

A conceptual study of interfering object removing operation in RPV bottom part finished and element tests areunder planning.
Processingarm

Processing tool (for upper part work)(with grasping and cutting functions)Collection arm
Collection arm(grasp processed pieces and carry them into acollection can)UC (⌀400, ⌀200)

Attached fueldebrisFuel Debris
Processing tool(such as AWJ and laser)
Opening for bottom part work
(to be required before starting bottom part work)

CRD housing

Stub tube

CRD housing
Processing tool (for bottom part work)(with grasping and cutting functions)

Schematic illustration of interfering object removing
operation in RPV bottom part

Schematic illustration of stub tube removal work
©International Research Institute for Nuclear DecommissioningNo.114

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method to remove interfering objects by fuel debris retrieval equipment by the top entry method
A top-entry and side-entry combined method, where the top entry method is used to process fuel debris andinterfering objects and the side entry method is used as a route to remove processed pieces out of the reactor, isbeing studied.
Collection arm(grasp processed pieces and carry theminto a collection can)Collection arm

UC (⌀400, ⌀200)

Processing tool (for upper part work)(with grasping and cutting functions)

Fuel Debris
UC (⌀400, ⌀200)

CRD housing

Processing tool(with grasping and cutting
functions)

Opening for fuel debris carrying-out(to be required before starting carrying-out)

Guide rail

Fuel Debris

UC (⌀400, ⌀200)

Schematic illustration of conducting work using only the top entry method

Schematic illustration of conducting work using the top-entry
and side-entry combined method©International Research Institute for Nuclear DecommissioningNo.115

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
a. Method to remove interfering objects by fuel debris retrieval equipment with the top entry method
FY2017 (Heisei 29)

FY2018 (Heisei 30)

Items to study
4

Key milestones

5

6

7

8

9

10

11

Interim report


12

1

2

3

4

Annual report


5

6

7

8

9

10

11

12

Interim report12Annual report

1. Conceptual study

2. Element test plan
3. Preliminary tests
required for element
test plan

4. Element test preparation(Test device production)
5. Element Tests
6. Wrap-up

Notes

3

Achievements from element tests
1. Feasibility of processing method for narrow parts
2. Feasibility of processing method taking into account fall prevention
3. Feasibility verification of workability by the top entry method, the side entry method, or a combination of them
4. Throughput calculation.
©International Research Institute for Nuclear DecommissioningNo.116

7. Implementation Details
7.2. Implementation Details: Element tests under2) Element technology development for installing retrieval equipment
planning[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method
Removal procedures were designed for all structures and objects identified as interfering objects based on the
results of the PCV inside investigation and considering steps from debris sampling in the PCV to remove fueldebris.
Interfering object dismantlement
procedures (proposed)
Flow of Debris

Sample debris in
PCV*1

Flow of cut pieces (non-debris)

Obstacle dismantlement

Open the equipment
hatch

HVH dismantlement

Remove stairs andstages[2] Transportation ofwaste, debris, etc.

Remove verticalladders andhandrails(UC and containers are
optional)

Remove CRD
and CRD
housing

Obstacles (HVH, etc.)

The procedures shown in the flowchart on the right establish an access route to the inside of the pedestal as well.
After establishing an access route to the inside of the pedestal, it will be judged whether the removal of fuel debris in
the PVC bottom via the established access route can be prioritized, by which only a small amount of fuel debris canbe carried in each work cycle, or large amount of fuel debris should be removed after removing all interfering
objects in the pedestal, according to the further progress of the program.

Remove pipes
and support
structures

Remove CRD
platform

Removal ofdebris in the PCV
bottom*1: it is not planned to remove structures outside the pedestal for sampling debris in the PVC.
©International Research Institute for Nuclear DecommissioningNo.117

7. Implementation Details
7.2. Implementation Details: Element tests under2) Element technology development for installing retrieval equipment
planning[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method
Removal procedures were designed for all structures and objects identified as interfering objects based on the
results of the PCV inside investigation and considering steps from debris sampling in the PCV to remove fueldebris.
Interfering object dismantlement
procedures (proposed)
Removal ofstructures inside X-6
penetration

Biologicalshielding wall
X-6
Penetration

PCV Wall

CRD, CRD housing, etc.
Remove CRD rails

CRD rail

PCV insidedetailed
investigation*1

CRD exchangeequipment

Sample debris in
PCV*1

CRD platform(Grating)
CRD platform(Grating support structure)

Remove biologicalshielding wall

Remove CRD
and CRD
housing

Open PCV wall

The procedures shown in the flowchart on the right establish an access route to the inside of the pedestal as well.
After establishing an access route to the inside of the pedestal, it will be judged whether the removal of fuel debris in
the PVC bottom via the established access route can be prioritized, by which only a small amount of fuel debris can be
carried in each work cycle, or large amount of fuel debris should be removed after removing all interfering objects inthe pedestal, according to the further progress of the program.

Remove X-6
penetration*1: it is planned to conduct PCV inside detailed investigations and the PCV inside debris sampling using the arm method.

Remove CRD
platform

Removal ofdebris in the PCV
bottom©International Research Institute for Nuclear DecommissioningNo.118

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method
Interfering objects that need to be removed were identified and listed.

: Element tests under planning

Note: A difficulty level is determined by relative evaluation
No.

Interfering objects

General specifications(m)

1

Biological shielding wall

[1] Main material

Reinforced concrete[2] Main dimensions
Thickness 1800 mm
Formwork iron plate:
3.2t

Suggested
processing
methods
Core boring
Wire saw

Example of removing method[1] Cut and remove concrete around X-6 penetration.
[2] Install a shield door.
[3] Cut an opening in the BSW wall by boring overlapping
boreholes along the circumference of the intended
opening[4] Carry out removed cores through the sleeve.

RemoveDifficulty
level

Notes

MediumX-6
Penetration

23

X-6 Penetration

PCV Wall[1] Main material
SA516 Gr. 70[2] Main dimensions
Outer diameter: 609.6,
thickness: 31, length:2176

Core boring
Thermal cutting(laser, gas)[1] Main material
SA515 Gr. 70[2] Main dimensions
Rounded surface with aradius of 10000 and a
thickness of 30[3] Dimensions of opening
W1500 x H2000 mm

Thermal cutting(laser, gas)

[1] Install a cell with sealing and shielding ability thatencompasses X-6 penetration on the outer wall of
BSW.
[2] Remove concrete around X-6 penetration by coring.
[3] Cut the exposed concrete sleeve in a longitudinal
direction and remove.
[4] Trim and cut the exposed X-6 sleeve from outside.
[5] Cut out the PCV wall around X-6.

[1] Insert an inflate seal between BSW inner surface
and the PCV.
[2] Mark a cutting line.
[3] Cut the PCV wall along the line by laser.
[4] Collect cut pieces in a container and remove.

Low

When adopting the method
for removing X-6
penetration, cut it together
with the PCV wall andremove mixed cut pieces.
If adopting the method to
use the opening of X-6
penetration as it is, it isassumed that interfering
objects inside X-6
penetration will have been
removed inside the PCV
during the detailed
investigation.

Low©International Research Institute for Nuclear DecommissioningNo.119

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method
Interfering objects that need to be removed were identified and listed.

Note: A difficulty level is determined by relative evaluation

No.

4

5

6

Interfering objects

General specifications(m)

Suggested
processing
methods

Example of removing method

CRD rail[1] Main material
SUS+SS[2] Main dimensions
L 6.2  W 0.6  H 0.24,
thickness = 10 mm

Disc cutter, saber
saw, thermal
cutting (laser/gas)[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container andcarry them out (via the equipment
hatch).

[1] Main materialSS[2] Main dimensions
Thickness 38 mm
Pitch 0.03 x 0.1

Disc cutter, saber
saw[1] Main materialSS[2] Main dimensions
Thickness 22 mm

Disc cutter, saber
saw

Grating

Grating support
structure

RemoveDifficultylevel

MediumNotes

It is assumed that the
CRD rail will havebeen removed inside
the PCV during thedetailed investigation.

[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container andcarry them out (via the equipment
hatch).
Low[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container andcarry them out (via the equipment
hatch).

Low©International Research Institute for Nuclear DecommissioningNo.120

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method
Interfering objects that need to be removed were identified and listed.

Note: A difficulty level is determined by relative evaluation

No.

Interfering objects

7

Equipment hatch andshield plug

8

9

HVH

Stairs in front ofairlock/stage

General specifications(m)

Suggested
processing
methods[1] Main material• Shield plug:
Reinforced concrete• Hatch: SS[2] Main dimensions• Shield plug:
W3.5  H2.8  L1.6
• Hatch: ⌀3.23 x T60 mm• Shield plug:
Wire saw[1] Main materialSS[2] Main dimensions
H2.5  W1.24  L2.5

Disc cutter, saber
saw, hydraulic cutter[1] Main materialSS[2] Main dimensions• Stairs: L3.3
Frame thickness 11 mm
Stair plate thickness 38 mm• Stage: floor plate thickness 20mm
2.0  1.2  0.8

Hatch:
Disc cutter

Disc cutter, saber
saw

Example of removing method[1] Cut the shield plug on the push stroke
by a wire saw or the like.
[2] Cut the hatch by a disc cutter or the
like.
[3] Collect cut pieces in a container andremove.

[1] Cut the face panel by a disc cutter.
[2] The cutting method for internal devices
is to be determined separately (basedon suitability)[3] Collect cut pieces in a container andcarry them out (via the equipment
hatch).

RemoveDifficulty levelNotes

MediumHigh• Cutting ducts in a highposition• Processing in narrow
areas• Cutting structures withcomposite/sophisticatedshapes(Tests were conductedlast fiscal year)[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container andcarry them out (via the equipment
hatch).
Low©International Research Institute for Nuclear DecommissioningNo.121

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method
Interfering objects that need to be removed were identified and listed.

: Element tests underplanning

Note: A difficulty level is determined by relative evaluation
No.

Interfering objects

10

Vertical ladders and handrails

11

Pipes and support
structures

Backside of the PLR
piping (underground)

General specifications(m)

Suggested
processing methods

Example of removing method[1] Main materialSS[2] Main dimensions⌀34mm
sch.40Disc cutter, saber saw[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container and carrythem out (via the equipment hatch).

[1] Main materialSS[2] Main dimensions• Pipe: approx. ⌀ 0.03-0.1
Sch.40• Support structures:
Max 0.1 x 0.1

Disc cutter, saber saw

RemoveDifficulty
level

Notes

Low

[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container and carrythem out (via the equipment hatch).

Mediumto high

Accessing g pipes locatedin areas blocked by otherstructures, or in areas
densely populated bypipes themselves, andwhat procedures to betaken are challenging
though cutting a pipe itself
is rather easy.

Around sump pit (underground)©International Research Institute for Nuclear DecommissioningNo.122

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval

b. Method to remove interfering objects by fuel debris retrieval equipment by the side entry method(1) Means and methods for removing interfering objects outside the pedestal
While removing equipment outside the pedestal does not require a special method, removing pipes andpiping support structures located near the worker access port are more difficult level and requireelement tests.
⚫ Purpose of development➢ Feasibility verification of workability in a narrow space➢ Feasibility verification of a processing method taking fall prevention into account.
⚫ Issues to be resolved➢ Processing method for narrow parts➢ Remote controlled workability⚫ Expected results➢ Feasibility of processing method for narrow parts➢ Feasibility of processing method taking into account fall prevention➢ Throughput calculation.
©International Research Institute for Nuclear DecommissioningNo.123

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method(1) Means and methods for removing interfering objects outside the pedestal
Schematic illustrations of element tests for removing piping and support
structures outside the pedestal are shown below.
Opening of Grating
Assistance robot

Collection canInterfering object removal
equipment(muscular robot)

Worker access port

Piping outside
Pedestal
support structures

Schematic illustration of interfering objects
outside the pedestal

Fuel Debris(spreading area is ahypothetical image): Element test simulation range

Removal of piping and its support outside the pedestal
Schematic illustration of element tests©International Research Institute for Nuclear DecommissioningNo.124

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment with the side entry method(1) Means and methods for removing interfering objects outside the pedestal
Test mock-ups provided to narrow-area processing tests, methods to access the pedestal basement, andequipment necessary to process and remove interfering objects and fuel debris are being studied.
Assistance robot

Lift to basement
Lift to basement
Simulation
range

Worker access port
location

Test mockups

Test mock-ups

View angle View angleof illustration of illustrationon lefton right

Flexible structure arm base(Jet deflector platform)
Simulating tasks fornarrow parts
Flexible structure arms (two hands)
to process interfering objects andfuel debris

Flexible structure arm base(Jet deflector platform)

Simulating tasks fornarrow parts

Flexible structure arms (two hands)
to process interfering objects andfuel debris©International Research Institute for Nuclear DecommissioningNo.125

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method to remove interfering objects by fuel debris retrieval equipment by the side entry method(1) Means and methods for removing interfering objects outside the pedestal
FY2017 (Heisei 29)

FY2018 (Heisei 30)

Items to study
4

Key milestones

5

6

7

8

9

10

11

Interim report


12

1

2

3

4

Annual report


5

6

7

8

9

10

11

Interim report


12

1

2

Annual report

1. Conceptual study

2. Element test plan
3. Preliminary tests
required for element
test plan

4. Element test preparation(Test device production)
5. Element Tests
6. Wrap-up

Notes

3

Achievements from element tests
1. Feasibility of processing method for narrow parts
2. Feasibility of processing method taking into account fall prevention
3. Throughput calculation.
©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1267.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval

b. Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Purpose of development➢

Establish means and methods to cut an opening in the PCV✓

All these methods are based on the concept of expanding X-6 penetration or having an additional opening to its
periphery and considering biological shielding wall (BSW) and PCV wall are common interfering objects.

✓

Core boring will be used for the BSW opening construction.

•

This is a remotely controlled, but proven, technology so there shouldn’t be any issue under normal
conditions⚫ Issues to be resolved➢

The feasibility of the BSW opening construction (using core boring) by remote operation needs to be verified, including

feasibility under abnormal conditions.
➢

The feasibility of measures to prevent the diffusion of dust and liquid waste generated during processing needs to beverified.

©International Research Institute for Nuclear DecommissioningNo.127

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval

b. Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinsideElement test for BSW boring until February 2018 (Phase 1)⚫ Development approach➢➢

The development will be carried out in three phases to review
feasibility and flexibility in planning.
✓ Phase 1: Applicability evaluation and test planning throughdesk study✓ Phase 2: Applicability evaluation by element tests✓ Phase 3: Prototype cutting tests using M/U module
Before proceeding to the next phase, expert review is provided⚫ Expected results➢➢

Selection and evaluation of technologies used for the opening
construction
Maintenance and recovery procedures (proposed)✓ Procedures for recovery from abnormal conditions✓ Procedures to exchange a core sleeve in a temporary cell

•Boring, core sleeve exchange, and jam
recovery

BSW test
facility

Boring equipment (Core boring)

Full-scale BSW boring test

July-August 2018 (Phase 3)• Automated boring system
operable under a highradiation environment• Equipment for jam recovery• Verification of procedures inreal scale operating range

Boring equipment(Core boring)Temporarycell

Cutting an
opening of
1.5 x 2 m

BSW test facility
Test mock-ups
simulating shielddoor©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1287.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method for removing interfering objects by fuel debris retrieval equipment used in the side
entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm toaccess the inside⚫ Development goals➢ Boring equipment and positioning equipment shall work together smoothly to perform accurate boring.
➢ The equipment shall perform boring smoothly in a given operation space that is assumed from theactual work condition in the reactor concerned.
➢ The recovery procedure restoration from abnormal conditions in a real scale operating range.
➢ The core sleeve can be exchanged using a crane installed in the temporary cell.
➢ Chip and crumb collection/wastewater treatment equipment shall function properly.

©International Research Institute for Nuclear DecommissioningNo.129

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2]

Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Test and judgment conditions (examples)➢➢Core sleeve: 200 mm or 250 mm (for recovery)
Dimensions of test facility:

Item

Value

Height

0.8 m

Width

1.2 m

Depth

1.8 m

* A 3.2 mm thick steel plate is attached to one facewith dimensions of 0.8 m x 1.2 m (on PCV side) tosimulate the actual reactor structure.
➢ Target time:✓✓

3 hours per core for boring and extraction
0.5 hour for recovery from stuck state* Specific values will be determined during the course of study.
©International Research Institute for Nuclear DecommissioningNo.130

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2]

Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫

BSW boring flow chart
Crane

Install BSW boring
equipment
Carry in a core sleeveand load in the position

Core sleeve
BSW boring
equipment

Shield door open

Repeat thesesteps until the
opening withpredetermined
dimensions isconstructed.

BSW opening

Core sleeve

Shield door closed

Unloading and carryingout of the core sleeveCore sleeveUninstall BSW boring
equipment
Transfer
carriage©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1317.2. Implementation Details2) Element technology development for installing retrieval equipment[2]

Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫

Test overview and check items
A feasibility study will be conducted through the following two-step test. Tests will be conducted with a viewto examining technologies applicable to other methods in common while test conditions are set based on
Plan-B2 of the side entry method.
[1] Element tests (Unit tests)
A test facility that reproduces the thickness (1.8 m), hardness and reinforcement layout of BSW is built.
Boring (core boring) is performed by boring equipment.
-> Verify ability to remove concrete core
Ability to construct overlapping boreholes is to be verified.
Verify ability for jam recovery tasks[2] Element tests (combination tests)
A test facility that simulates the PCV wall and the thickness, hardness and reinforcement layout of BSW
is produced.
A temporary house that simulates a work cell is installed.
-> (The same evaluation items as those of the element tests are to be verified.)
Verification of positioning accuracy
Verify workability in a temporary house.

©International Research Institute for Nuclear DecommissioningNo.132

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
b. Method for removing interfering objects by fuel debris retrieval equipment used in the side
entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm toaccess the inside⚫ Requirements◆ An opening necessary to install a work cell shall be able to be constructed.

◆ Existing PCV shall not be damaged.
➢ The BSW boring work is performed outside the existing primary boundary. It must
not cause damage to or degrade the existing primary boundary.
◆ Reduce diffusion of radioactive materials via chip and crumb or wastewater.
◆ Worker exposure associated with tasks shall be reduced.

©International Research Institute for Nuclear DecommissioningNo.133

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2]

Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Environmental requirements◆ Area around X-6 penetration on R/B 1F is assumed➢

Dose rate (R/B 1F): 5-10 mSv/h➢

Acceptable maximum load of floor surface: 4.9 ton/m2➢

Height limit: 3 m (no interference with RHR piping)◆ Specifications of BSW:➢

Material: reinforced concrete with the strength of 500-600 kg/cm2, designed reinforcement bar
layout needs to be considered.

➢Thickness: 1.8 m, the presence of a formwork steel plate (3.2 mm) on the backside of BSW
needs to be considered.

➢

D38-SD345 reinforcement bars are arranged in a two-layer-two-stage formation (horizontal pitch:
approx. 180-200 mm, vertical pitch: approx. 200-400 mm).

◆ Temperature: 0-40°C◆ Humidity: Same level as the atmosphere outside the facility◆ Designed lifetime: max. about one year (to be sound only during boring work)©International Research Institute for Nuclear DecommissioningNo.134

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinsideTest device/equipment
Actual device/equipment⚫ Basic BSW boring equipment configuration
Chip and crumbcollection/wastewater
Shield door treatment equipment

Design basis strength: 225 kg/cm2*1
Thickness：1800 mm
Reinforcement layout: D38-SD345 (2 layer 2stage layout)
Size: Curvature radius of outer surface 11700,
Curvature radius of inner surface 10074
Formwork: 3.2 mm steel plate (one side)

BSW

Temporary cell
Recoveryequipment⌀200  L3540 (estimated)Core sleeve

BSW formwork
BoringHydraulic motor for both rotation and linear
motion in axial direction
Full automatic positioning by X-Y positioning
system.

Drive unit

equipment

Positioning
equipment

Temporary cell
ventilation system

Recoveryequipment

Installed between BSW and the shield door to cut
the core sleeve

Wire saw

Large-bore core ⌀250  L3540 (estimated)

Shield door

Both shielding and air tight functions are required.

Temporary cell

Installed to prevent contamination spread duringboring work

Crane in temporary cell

Crane in temporarycell

Boringequipment

Two cranes for work in the temporary cell

Temporary cell ventilation
systemChip and crumb collection
equipment andwastewater treatment
equipment

Generated dust are collected by filter ventilation
systemCollect wastewater containing concrete chips
generated during coring.

*1: The test facility shall simulate the actual strength of 500-600 kg/cm2.
Note: This is the current plan and is subject to change according to the progress of design.
©International Research Institute for Nuclear DecommissioningNo.135

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫

BSW opening work procedure (1/2)
Shielddoor

Temporary
cell

Crane
Core sleeveCore sleeve
BSW boring
equipment[1) Installation of temporary cell and BSW boring equipment]
Install a temporary cell and biological shield wall (BSW)
boring equipment by workers’ construction work. The
temporary cell is installed to prevent the dispersion of dust
generated during BSW boring.

Transfer
carriage

BSW boring
equipment[2) Carrying-in core sleeves]Move the transfer carriage loaded with acore sleeve into the temporary cell byworkers.

Shielddoor[3) Loading of core sleeve onto BSW boring equipment]
Workers load the core sleeve onto BSW boring
equipment using cranes in the temporary cell. Adjust
the position of the core sleeve after loading.

Core sleeveCore sleeve[4) Shield door opening task]
Open the shield door by remote
operation.

[5) Boring of BSW]
Dig the core sleeve into BSW and bore it and its
formwork (3.2 m thick) by remote operation until athrough-hole is constructed. The completion of athrough-hole is detected by change in oil pressuregauge reading.

[6) Collecting core sleeves]
Retract the core sleeve to its original position
by remote operation after a through-hole isconstructed.

©International Research Institute for Nuclear DecommissioningNo.136

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ BSW opening work procedure (2/2)
Overhead Crane

Core sleeve

Transfer carriage

Shield door

Core sleeve[8) Loading of the used core sleeve onto atransfer carriage]
Workers unload the used core sleeve from
BSW boring equipment and load it onto atransfer carriage using an overhead crane.

[7) Shield door closing task]
Close the shield door by remote
operation.

TemporarycellTransfer carriage[9) Transferring core sleeves]Move the transfer carriage loaded with the used core
sleeve out of the temporary cell by workers.
* Repeat steps 2) to 9) until an opening with a widthof approx. 1.5 m and a height of approx. 2 m isconstructed in BSW.

Shielddoor[10) Remove the temporary cell and BSW boring equipment]
After completion of the BSW opening with intended
dimensions, workers dismantle the temporary cell and BSW
boring equipment.

Note: This is the current plan and is subject to change according to the progress of design.
©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1377.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Procedures for jam recovery
Wire saw

Temporary Shield
door
cell

Crane

Core sleeveCore sleeve[0) Stuck (before starting tasks)]
Core sleeve (⌀200) involves rebar fragments andgets stuck during coring.

Wire saw[1) Severing core sleeves]
Cut the stuck core sleeve by the remote operation of awire saw installed between BSW and the shield door.
Retract the cut core sleeve toward the original position
after cutting.

Boringequipment

Transfer
carriage[2) Withdrawal of the core sleeve]
Close the shield door by remote operation. Workers unload
the core sleeve (⌀ 200) from boring equipment, load it onto
a transfer carriage using a crane, and move the carriage
out of the temporary cell.

Core sleeve

Crane

Large-bore core sleeve

Large-bore core sleeve

Boringequipment[3) Attachment of the large-bore core sleeve]
Workers carry in the large-bore core sleeve (⌀ 250)
and load it onto the boring equipment using a crane.

Note: This is the current plan and is subject tochange according to design progress.

[4) Coring with the large-bore core]
Open the shield door by remote operation. Locate thelarge-bore core sleeve at the position so that the largebore core sleeve encompasses the ⌀ 200 core sleeve
cut and left in BSW, dig it into BSW by remote
operation, and bore BSW and BSW formwork (3.2 m
thick) until a through-hole is constructed. The
completion of a through-hole is detected by change inoil pressure gauge reading.

[5) Withdrawal of the large-bore core sleeve]
Retract the large-bore core sleeve to the original
position by remote operation after completion ofboring, and close the shield door by remote
operation. Workers unload the used large-bore core
sleeve from boring equipment and load it onto atransfer carriage using a crane. (-> Return to Step 2)of normal operation)©International Research Institute for Nuclear DecommissioningNo.138

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Evaluation items in the test
Test

Evaluation item

Element tests (unit tests)
Recovery equipment(Wire saw)

Boring equipment• Coring shall be achieved with intended accuracy.
• Coring shall produce overlapping boreholes (Hole deviation from the intended position
shall be measured)• Obtains parameters concerning boring tasks (hydraulic pressure for core rotation, feed
per rotation, and volume of water consumption).
• Cores shall be able to be removed.
• The exchange of a core sleeve (loading and unloading) shall be able to be performed.
• A means to recover from core sleeve jam and restore normal operation shall be
BSW test facility
provided.

Element tests(combination tests)• Coring task shall be performed with intended accuracy by applying parameters obtainedby element tests (unit tests).
• Cores shall be able to be removed.

Chip and crumbcollection/wastewater
treatment equipment

Cutting an opening of• The exchange of a core sleeve (loading and unloading) shall be able to be performed.
approx. 1.5 m x 2 m

Recoveryequipment
Boringequipment

BSW formwork
BSW test facility

Shield door (testmock-up)• A means to recover from core sleeve jam and restore normal operation shall be
provided.
• The test system simulating actual unit achieves opening with a BSW simulant test
facility equivalent to actual units (including core sleeve attachment and detachment,
coring, dust collection, wastewater collection and recovery).
• Data shall be able to be obtained so that the data is used to develop ideas to measuresetup work time and shorten it.

Temporarycell©International Research Institute for Nuclear DecommissioningNo.139

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinsidealmost thepartially⚫ Basic test device configuration
same as actual
Legenddevice,Test device/equipment

About 10boreholes

Boring equipment (Core boring)

BSW boring element tests (combination tests)

Boringequipment

Recovery equipment
Cutting an openingof 1.5 x 2 m(typical 25 positions)Temporary cell
ventilation system

BSW
formwork

BSW facility
Temporary cell

BSW test facility
Recovery Boring equipment
equipment

BSW boring element tests (Unit tests)

Unit tests(including formwork)

simulated,

Not applicable

Combination tests(including formwork and PCV)

Core sleeve
Drive unit
Positioning
equipment
Wire saw
Large-bore
core

Shield door
Temporary cell
Crane intemporary cell
Temporary cell
ventilation system
Chip and crumbcollection equipment
and wastewater
treatment equipment

Shield door (test mock-up)©International Research Institute for Nuclear DecommissioningNo.140

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Test procedures and criteria
Criteria/targets

Core boring

Element tests (unit tests)

Element tests (combination tests)

Boring• Overlapping boreholes shall be constructed in the test facility (thatsimulates strength, thickness and reinforcement layout).
• A steel plate attached to the test mock-up to simulate the BSW
formwork shall be processed together.
• Angled boring with the gradient required by design (⊿3/200 or so)shall be possible.
• Equipment shall operate smoothly.
• Obtain optimum core sleeve size and criterion to decide overlap
width• Boring equipment and positioning equipment shall work
together smoothly for proper boring.
• The equipment shall perform boring smoothly in a given
operation space (limited space) that is assumed from theactual work condition in the reactor concerned.

Working water volume

The predetermined rate of water supply (2-3 L/min) shall be verified.

Work time

The cycle time of core boring shall be measured. (Target cycle time: 3 hours per core for boring and core retrieval)

Wastewater

The amount and properties (particle size of chips contained andcharacteristics of wastewater such as viscosity) of generated
wastewater shall be investigated by sampling the wastewater.

Detection of the boringhead reaching the otherend and stopping ofoperation
Retrieval of aconcrete coreCore sleeve
exchange(attachment anddetachment)Core sleeve
recovery/restora
tion

Chip and crumb collection/wastewater treatment equipment
shall function properly.

The overtravel distance of the boring head beyond the other side surface of BSW shall be 40 mm or less. The completion of a throughhole is detected by change in oil pressure gauge reading.

Retrieval of a core

The core sleeve and cores shall be pulled out of the test facility and removed.

Time measurement

Time necessary to retract the core sleeve shall be measured. (Target time: 3 hours per core for boring and core retrieval)Core sleeve attachment
and detachment for
exchange

Core sleeve exchange
supported.

or attachment

and detachment

areTime measurement

Manage time for core sleeve exchange including attachment anddetachment (Target time: 0.5 hour)Core sleeve
recovery/restoration

The boring equipment shall recover from the state of stuck core
sleeve. (verified by simulation test if the core sleeve doesn’t get stuck)

Frequency, timemeasurement

Investigation of the frequency of jamming and time necessary forrecoveryCutting of a core sleeveCore sleeve can be exchanged using a crane installed in thetemporary house.

The equipment shall be provided with a means to recover fromcore sleeve jam that is operable in a given space that isassumed from the actual work condition in the reactor
concerned.

The core sleeve shall be cut by a wire saw at a predetermined position. The behavior of the cut core sleeve shall be observed©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1417.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Check items in unit tests
No. Purpose and influence

Element tests (unit tests)
Boring equipment (Coreboring)Construction of
about 13boreholes isplanned.

Check items (Unit tests)[1]• Construction of an opening of intended
dimensions (with intended accuracy)• Ability to accommodate an inflate seal

Straightness change by boring position
Appropriate boring position and range[2]• Construction of an opening of intended
dimensions (with intended accuracy)
Overla• Ability to accommodate an
inflate seal

Variation in straightness due to variation in
overlap width
Appropriate overlap widthCore sleeve size: ⌀200 × L3540

p widthElement tests (combination tests)

Recovery equipment
Boring equipment
Crane intemporary cell

Cutting an openingof 1.5 x 2 m(typical 25
positions)Temporary cell
ventilationequipment• Construction of an opening of intended
dimensions[3]• No damage in other part of PCV.
(No damage on the primary boundary)

Ability to process BSW formwork
The overtravel distance of the boring headbeyond the other side surface of BSW(influence of position and overlap width)[4] • Chips and wastewater collection

Gradient necessary to drain wastewater[5]
BSW
formwork

BSW test
facility
Temporary cell

Shield door (test mock-up)• Determination of specifications of utilities andWater volume required during work
wastewater collection facilities[6] • Overall process period

Work time[7]• Construction of an opening of intended
dimensions

Ability to construct overlapping boreholes underconditions assumed in the actual
decommissioning work

[8]

• Recovery• Overall process period

Recoverability(cutting of a core sleeve by a wire saw)
©International Research Institute for Nuclear DecommissioningNo.142

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside<List of detailed boring conditions>⚫ Evaluation items in the test
Boring position and boring order for a test facility

No.

Overlap width

Gradient

Angle
[]

Main check items

X

Y

1

0

0

-

0

0

2

-400

200

-

0

0

3

400

200

-

0

0

4

-350

200

Lateral overlap 150 mm

0

0

5

-250

200

Lateral overlap 100 mm

0

0

6

-100

200

Lateral overlap 50 mm

0

0

7

170

0

Lateral overlap 30 mm

0

0

8

-400

-200

-

⊿1/50

0

9

-150

-200

-

⊿3/200*3

0

10

170

-200

-

⊿1/100*3

0

11

-400

65

Top overlap 65 mm⊿3/200*3

4

12

-265

65

Top overlap 65 mm, lateraloverlap 65 mm⊿3/200*3

4[7]*4Overlapping boreholes
assumed in the actual
decommissioning work65

Top overlap 65 mm, lateraloverlap 65 mm⊿3/200*3

4[8] Recovery

13

Numbers in the figure correspond to those in the list

Borehole position(coordinates)*1-130

Supplementary
check item

[1]*2 Straightness[1] Straightness[2] Overlap width[3] Formwork boring[6] Work time[4]Wastewater drainage
gradient[5]Water volume[3]Formwork boring

Numbers in these columns*1: The center of the test facility shall be the origin of coordinates (X, Y = 0, 0).
correspond to Check Item No.
*2: Straightness in No. 1 borehole processing is compared with those in boreholes No.2 and 3 processing.
*3: If wastewater drainage is found to be difficult in the No.8 borehole processing with the gradient of ⌳ 1/50, an increase in gradient will
be considered.
*4: Comprehensive evaluation will be performed in the processing of the No.11 and 12 boreholes to feedback any findings in the boringof the actual BSW. The comprehensive evaluation includes the evaluation of the feasibility of boring with boring angles that are assumed
in boring the actual BSW (including the boring of the formwork), water supply rate and cycle time.
*5: These evaluation items are subject to change according to the design progress of design.

©International Research Institute for Nuclear DecommissioningNo.143

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinside⚫ Comparison of actual unit and test facility
Actual device/equipment
Shape
Type ofconcrete

Concrete strength

Type of reinforcement

Reinforcement layout
1st layer

2nd layer

Formwork

Specimen

Reason of change (if any)

The curvature radius of outer surface 11700, Curvature radius of
inner surface 10074
JIS A 5308 standard concrete(Fly ash cement Type B)
Nominal designation: Normal 225-15-25FB

W1240  H800 x D1800

Strength design requirement: 225 kg/cm 2**: Note that actual measurements in the long-term durability
investigation indicate 50-60 N/mm2 in some places.
Steel bar for reinforced concrete
D38  SD35 (JIS G3112)

Strength design requirement: 51N/mm 2(The target of the actual measurement is50-60 N/mm2)
Steel bar for reinforced concrete
D38  SD345 (JIS G3112)

Sage 1: vertical bar pitch 200 mm, horizontal bar pitch 200 mm
Sage 2: vertical bar pitch 200 mm, horizontal bar pitch 400 mm* The pitch of bars whose bottom is fixed in the floor concrete is 120
mm.
Sage 1: vertical bar pitch 200 mm, horizontal bar pitch 200 mm
Sage 2: vertical bar pitch 200 mm, horizontal bar pitch 400 mm* The pitch of bars whose bottom is fixed in the floor concrete is 120
mm.
Formwork made of 3.2 mm thick steel plate• Connected by ⌀10 joint bolts• Reinforced by L-shaped steel of 40  40  3Same as on the leftMaterial code change
due to conversion to SI unit system (nochange in actual material)-

Same as on the left-

Same as on the left-

100 pieces of formworks are used (laid out at 176.4 degree angle).

To make the installation angle the same-

For more reasonable cutout.

JIS A 5308 standard concrete(ordinary Portland cement)
Nominal designation: Normal 51-21-20N
To make it nearly equal to the actual
measurement

Explanation of concrete type coding (Standard ds-xx-yyzz)
Standard: Standard concrete, ds: Design base strength (225kg/cm 2, 51N/mm2), xx: slump or slump flow (cm), yy: max. size of coarse aggregate, zz: type of cement (FB: fly ash
cement Type B, N: ordinary Portland cement)©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1447.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalb.
Method for removing interfering objects by fuel debris retrieval equipment used in the side entry method(2) Hole drilling methods to enlarge the PCV opening to allow, for example, the robot arm to access theinsideFY2017 (Heisei 29)

Items to study
4

Key milestones

5

6

7

8

Phase 1: Desk study

9

10

11

FY2018 (Heisei 30)
12

Plan

1

2

3

4

5

6

7

8

9

10

11

12

1

2

Review-> Decision for starting test production of devices

a. Conceptual study/test plan
test device design
Test planningb. Test preparation/test device
test production

Procurement

Preparation

Phase 2: Element tests

c. Element Test
Unit tests

Phase 3: combination tests

Cutting tests(Additional tests)

d. Summary

Notes

Expected results[1] Selection and evaluation of technologies used for the opening construction[2] Maintenance and recovery procedures (proposed)⚫ Procedures for recovery from abnormal conditions⚫ Procedures to exchange a core sleeve in a temporary cell
©International Research Institute for Nuclear Decommissioning3

No.145

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalc. The method for removing interfering objects by fuel debris retrieval equipment is commonly usedin access from both entries.
Interfering objects that need to be removed were identified and listed.

: Element tests under planning

Note: A difficulty level is determined by relative evaluation
No.

1

2

3

Interfering objects

Grating

Grating support
structure

CRD, etc. (fallen
objects)

General specifications(m)

Suggested
processing
methods[1] Main material
SS + fuel debris[2] Main dimensions
Thickness 38 mm
Pitch 0.03 x 0.1

Disc cutter,
Saber saw

[1] Main material
SS + fuel debris[2] Main dimensions
Thickness 13.5 mm⌀4.85(diameter)

Disc cutter,
Saber saw

[1] Main material
SUS + fuel debris[2] Main dimensions
Thickness 18 mm⌀0.16Disc cutter,
Saber saw

Example of removing method

RemoveDifficulty levelNotes• Fuel debris is adhered• An irregular shape ispredicted due todeformation/erosion.

[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container and carrythem out (via the equipment hatch).
Medium• Fuel debris is adhered• An irregular shape ispredicted due todeformation/erosion.

[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container and carrythem out (via the equipment hatch).
High[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container and carrythem out (via the equipment hatch).
High• Fuel debris is adhered• There is a risk of falling
reactor internals.
• An irregular shape ispredicted due todeformation/erosion.

©International Research Institute for Nuclear DecommissioningNo.146

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalc. The method for removing interfering objects by fuel debris retrieval equipment is commonly: Element tests under planning
used in access from both entries.
Interfering objects that need to be removed were identified and listed.
Note: A difficulty level is determined by relative evaluation
No.

Interfering objects

General specifications(m)

4

CRD exchange system[1] Main material
SS + aluminum + SUS + fueldebris

Suggested
processing methods
Disc cutter,
Saber saw

Example of removing method[1] Cut it by a disc cutter or the like.
[2] Collect cut pieces in a container andcarry them out (via the equipment
hatch).

RemoveDifficulty level

High

Notes

• Fuel debris is attached.
• An irregular shape ispredicted due todeformation/erosion.

[2] Main dimensions
W0.9  L0.7  H4.0

©International Research Institute for Nuclear DecommissioningNo.147

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalc. The methods to remove interfering objects by fuel debris retrieval equipment are commonly used inboth side entry and top entry.
(1) The means and methods for removing interfering objects inside the pedestal
Fallen objects and inner structures in the pedestal are interfering objects, regardless of whether
the top entry or the side entry method is used. It is also true that both methods are applicable to
the removal of those objects. From the aforementioned perspective, element tests for methods
to remove/dismantle those object are planned.
⚫ Purpose of development➢ Feasibility verification of workability in a narrow space➢ Feasibility verification of a processing method taking fall prevention into account.
⚫ Issues to be resolved➢ Remote controlled workability➢ Processing method for narrow parts➢ Removing method that taking fall prevention into account.
⚫ Expected results➢ Feasibility of processing method for narrow parts➢ Feasibility of processing method taking into account fall prevention➢ Throughput calculation.

©International Research Institute for Nuclear DecommissioningNo.148

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalc. The method for removing interfering objects by fuel debris retrieval equipment is commonly used inaccess from both entries.
(1) The means and methods for removing interfering objects inside the pedestal
Schematic illustrations of element tests for the removal of fallen objects in the pedestal are shown below.
Pedestal Opening

Pedestal Opening

Fallen objects in the pedestal
Interfering object test mock-ups

Interfering object removal
equipment(muscular robot)

Pedestal Opening

Schematic illustration of the predictedcondition of fallen objects in the pedestal

Simulating the pedestal wall
opening and its vicinity

Schematic illustration of element tests
for the dismantlement of interfering
objects: Element test simulation range©International Research Institute for Nuclear DecommissioningNo.149

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalc. The method for removing interfering objects by fuel debris retrieval equipment is commonly used inaccess from both entries.
(1) The means and methods for removing interfering objects inside the pedestal
Simulation in the pedestal is planned to simulate fallen objects and take underwater tasks Into account.

Grating support structure
Water tank(simulating underwater task)

Fallen objects (pipe): Underwater task observation window
Pedestal Opening

Proposed test mock-ups in the pedestal©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1507.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrievalc. The method for removing interfering objects by fuel debris retrieval equipment is commonly used in accessfrom both entries.
(1) The means and methods for removing interfering objects inside the pedestal
Specific procedures of the dismantlement of interfering objects in the pedestal are being studied, along with thedesign of facilities for element tests, to verify proposed procedures.
Work
step

Preparation for dismantlement of interfering objects

Assembly of interfering object removal
equipment

Step diagram

Arm

Grip andprocess

Interfering
objects

Supportarm

Inside Pedestal

Work
step

Pedestal Opening

Holding removed objects/collection can
preparation

Support arm
extension

Interfering object
removal equipment

Removal of removed objects

Holding removed
objects

Step diagram

Fallen objects dismantlement status

Support arm extension/removing work
(repeat)
Support arm
extension

Collection can
preparation

Collection ofremoved objects©International Research Institute for Nuclear DecommissioningNo.151

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(1) The means and methods for removing interfering objects inside the pedestal
FY2017 (Heisei 29)

FY2018 (Heisei 30)

Items to study
4

Key milestones

5

6

7

8

9

10

11

Interim report


12

1

2

3

4

Annual report


5

6

7

8

9

10

11

Interim report


12

1

2

Annual report

1. Conceptual study

2. Element test plan
3.Preliminary tests
required for element testplan

4. Element test preparation(Test device production)
5. Element Tests
6. Wrap-up

Notes

3

Results of element tests
1. Feasibility of processing method for narrow parts
2. Feasibility of processing method taking into account fall prevention
3. Throughput calculation.
©International Research Institute for Nuclear DecommissioningNo.152

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonlyused in access from both entries(2) Maneuverability verification by a combination of robot arm and access rail
⚫ Purpose of development➢ Verification of the feasibility of basic mechanical motions and remote operability of eachequipment concerning interfering objects and fuel debris retrieval through the test that simulates
the motion of a robot arm and access rail combined mechanism⚫ Development approach➢ Conceptual study of interfering objects and fuel debris retrieval methods✓ Study of required arms (for interfering object removal equipment)✓ Study of a method to carry various types of arms in the pedestal➢ Element test plan
✓ Study of test methods and test items✓ Study of the possibility of using existing equipment (made last fiscal year) as well as new
equipment➢ Element tests preparation and implementation✓ Manufacturing of prototype device✓ Manufacturing of test facility✓ Element Test

©International Research Institute for Nuclear DecommissioningNo.153

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used inaccess from both entries(2) Maneuverability verification by a combination of robot arm and access rail
⚫ Issues➢⚫

Although functions of robot arms and access rails were verified individually inthe element tests last fiscal year, the whole process of the removal work thatinvolves all relevant equipment is not tested yet.
Feasibility of the transportation of those equipment from the cell to thepedestal and the ability to process debris in the pedestal are keys for the
retrieval method’s success and affect other facilities such as cells
significantly; therefore, feasibility of the whole removal process needs to beverified along with the identification of potential issues by conducting
combination tests.

Results of tests last fiscal year
➢ Prototypes of the following equipment were built andelement tests were performed with them as follows:
The technical feasibility of each equipment capable ofperforming required functions and the validity of the designs
were verified.
<Robot arm tests>[1] Verification of emergency withdrawal ability[2] Verification of positioning accuracy[3] Verification of strength<Access rail tests>[1] Verification of the feasibility of construction byremote operation[2] Verification of strength©International Research Institute for Nuclear DecommissioningNo.154

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Conceptual Study➢ The combination of a hydraulic robot arm with a reaction force of 2 tons and an access rail was studied in the conceptual
study last fiscal year as the method to process debris that piled in the pedestal bottom.
➢ Meanwhile, methods employing an electric powered arm, which has a wider motion range compared to a hydraulic arm,
were studied as a method to process interfering objects, such as the grating, because the processing of those objects
would require less power.
➢ No matter which arm is used, it needs to be carried into the pedestal by an access rail. Therefore, tests to verify theaccessibility by the arm and the access rail combined mechanism and the maneuverability of the combined mechanism toperform a series of required operations are planned.

Fuel debris removal

Removal of interfering object©International Research Institute for Nuclear DecommissioningNo.155

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail
[Schematic illustrations of interfering object removing work]
3. Cut PCV wall(leaving connecting part to CRD rail)

1. Cut X-6 penetration(leaving connecting part to CRD rail)

2. Cut PCV wall

5. Cut the back part of the CRD rail

6. Cut the front part of the CRD rail 7 Cut the remaining part of X-6
penetration

9. Cut the CRD exchange equipment 10. Cut CRD

11. Remove interfering objects inthe back part of the pedestal

4. Cut the gating located above X-6
penetration in PCV

8. Cut part of the grating that interferes
the installation of the access rail

12. Remove interfering objects inthe front part of the pedestal©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1567.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail

⚫ Element test approach➢➢➢➢

The use of an electric powered arm for the removing interfering objects and a hydraulic arm for debris removal
were studied in the conceptual study.
No matter which arm is used, the arm needs to be carried in the pedestal by an access rail.
The series of work steps is almost the same for both the dismantlement of interfering objects and the removalof debris, although the arm driving sources are different.
If accessibility by a hydraulic arm is verified by tests, accessibility by an electric powered arm is also ensured
because a hydraulic arm is larger in dimensions and weight.

Accessibility verification tests with the robot arm and access rail combined mechanism thatwere made last fiscal year are planned.
⚫ Identification of verification items➢➢

Verification iitems are identified by going over the w debris removal work steps because the series of work
steps is almost the same for both the dismantlement of interfering objects and the removal of debris.
The identified verification items are grouped into the groups of those for the verification of this project, for theverification to be conducted in the future, and for conceptual study/element tests from the following viewpoints:✓ To expedite feasibility verification of the method, items that need to be verified by tests in higher priority
are extracted.
(Items whose evaluation results make an impact on the method and its change are picked up.)
✓ Feasibility is verified for each of multiple issues in a step-by-step manner.
©International Research Institute for Nuclear DecommissioningNo.157

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Work steps and verification items

Work step

1. Carry the robot arm into the cell

2. Insert the robot armin the access rail

3. Install the robot armin the access rail

Step diagram

Verification
items(1) Traveling and running of equipment
between the cells[1] Ability to get over bumps andgaps at rail joints[2] Accuracy of stop position[3] Measures to prevent the carriage
losing balance and getting uneven(2) Utility supply to equipment during
traveling between cells[1] When passing the shutter[2] Cabling(1) Transit of arm robot to the access rail
(2) Connection of arm robot and transfer
carriage[1] Detection of connecting position[2] Position alignment by the transfer
carriage[3] Connection retained in case ofdrive source outage

Same as on the left

©International Research Institute for Nuclear DecommissioningNo.158

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail
⚫ Work steps and verification items
Work step

4. Tilt the access rail toward the opening for
CRD exchange

5. Extend the access rail

6. Move forward and expand the robot arm(1) Expansion and contraction of the accessrail[1] Speed[2] Motion range[3] Cabling[4] Shutdown accuracy[5] Possibility of vibration(2) Remote installation of access rails(Possibility of positioning using camera
image)(1) Carriage travelling[1] Speed[2] Motion range[3] Cabling[4] Shutdown accuracy[5] Possibility of vibration[6] Travelling performance of carriage to getover bumps at rail joints

Step diagram

Verification items(1) Tilting of the access rail
[1] Speed[2] Motion range[3] Cabling[4] Shutdown accuracy[5] Possibility of vibration-> Already verified by element test last year-> Already verified by element test last year
(Possibility of positioning in darkness using
camera image is not verified.)(2) Robotic arm on remote-controlled guidevehicle(3) Securing robot arm on the rail
[1] Retention force[2] Position retained even in case of drive
source outage©International Research Institute for Nuclear DecommissioningNo.159

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Work steps and verification items

Work step

9. Collect fuel debris fragments into theunit can placed in the transfer carriage
on the access rail

7. Move the robot arm close to fueldebris

8. Drill fuel debris with the tool tip ofrobot arm

(1) Interfering object/debris cutting point
targeting using camera image(2) Positioning accuracy of robot arm tip(1) Procedure for removing Interfering
objects(2) Interfering object removing method(3) Debris drilling method(4) Collection of chips generated during
interfering object and debris drilling(5) Bearing of reaction force generated bydebris drilling

Step diagram

Verification
items-> Already verified by element test lastyear(1) Interfering object and debris grabbing
method(2) Method to judge the cut size of objects
fitting into the unit can©International Research Institute for Nuclear DecommissioningNo.160

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Work steps and verification items

Work step

10. Transfer the unit can to the cellby the transfer carriage on the rail

11. Pick up the unit canwith the manipulator in the cell(1) Transfer carriage traveling[1] Descending move by gravity[2] Speed[3] Motion range[4] Shutdown accuracy[5] Possibility of vibration[6] Travelling performance of carriage
to get over bumps at rail joints(1) Method to hold the unit can(shape of the unit can)12. Put the unit can containing fueldebris in the canister with themanipulator in the cell

Step diagram

Verification
items(1) Method to store unit cans in thecanister(2) (Structure of the canister)[1] Lid fastening[2] Drying[3] Degassing©International Research Institute for Nuclear DecommissioningNo.161

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Work steps and verification items

Work step

OthersStep diagram-

Verification
items(1) Emergency escape[1] Change to robot arm transfer attitude -> Already verified by element test last year
[2] Robot arm retraction into cell (carriage travelling)[3] Retraction of the access rail
[4] Leveling the access rail
[5] Withdrawal of the access rail into the cell
(2) Environment resistance (radiation, temperature, humidity, dust and foreign matters)(3) Maintainability (camera replacement)(4) Exchange of tip tools(5) Feasibility of the whole process(6) Throughput©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1627.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Verification iitems and methods
Verification method

No.

Major issue

Verification items

1

Traveling of equipment
between the cells(1) Traveling and running of equipment between the cells[1] Ability to get over bumps and gaps at rail joints[2] Accuracy of stop position[3] Measures to prevent the carriage losing balance andgetting uneven(2) Utility supply to equipment during traveling between
cells[1] When passing the shutter[2] Cabling

2

Installation of the robot
arm in the access rail
(The gravity center ofrobot arm is outside thecarriage wheels)

Conceptual
Study

Element
Test[A](There is a
track recordin travelingcranes.)

-

-

[A]

Notes

(1) Transit of arm robot to the access rail

(2) Connection of arm robot and transfer carriage[1] Detection of connecting position[2] Position alignment by the transfer carriage[3] Connection retained in case of drive source outage©International Research Institute for Nuclear DecommissioningNo.163

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Verification iitems and methods
Verification method

No.

3

4

Major issue

Remotely controlled
installation of access rails• Gradient• Expansion and contraction• Fixing method to thepedestal• Positioning using camera
image

Carrying-in of the robot armin the pedestal(ability of the carriage to getover bumps at rail joints)

Verification items(1) Remotely controlled installation of access rails[1] Speed[2] Motion range[3] Cabling[4] Shutdown accuracy[5] Possibility of vibration(2) Possibility of positioning using camera(1) Traveling of the carriage on the access rail
[1] Speed[2] Motion range[3] Cabling (robot arm)
[4] Shutdown accuracy[5] Possibility of vibration[6] Travelling performance of the carriage to get over bumps at rail
joints(2) Robotic arm on remote-controlled guide vehicle(trackability of robot arm tip by camera)(3) Securing robot arm on the rail
[1] Retention force[2] Position retained even in case of drive source outage

Conceptual
Study

Notes
Element Test
[A]
• Verified last
year

-

[A]
(Cabling:
Proven withbearing andreels)• The sametests will be
performed
in darkness
this fiscal
year.

[A]
(except cablehandling)©International Research Institute for Nuclear DecommissioningNo.164

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Verification iitems and methods
Verification method

No.

5

Major issue

Interfering object anddebris processing (drilling)

Verification items

Notes

Conceptual
Study

Element Test

(1) Alignment of the robot arm on interfering object/debris cutting
points using camera image-[A]• Verified lastyear
• The sametests will be
performed in
darkness
this fiscal
year.

(2) Positioning accuracy of robot arm tip-• Verified lastyear(3) Processing (drilling) of interfering objects and debris[A](verified byother element
tests)(4) Collection of chips generated during interfering object and debris
processing (drilling)[A]-(5) Bearing of reaction force generated by interfering object anddebris processing (drilling)-[A]©International Research Institute for Nuclear DecommissioningNo.165

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Verification items and methods
Verification method

No.

Major issue

Verification items

6

Collection of processeddebris in the unit canTransportation of the unit
can within the cell(ability of the carriage to
get over bumps at rail
joints)7

8

Putting the unit can in thecanisterConceptual
Study

Element Test

(1) Interfering object and debris grabbing method(2) Method to judge the cut size of objects fitting into theunit can[A]-(1) Traveling of the transfer carriage on the access rail
[1] Descending move by gravity[2] Speed[3] Motion range[4] Shutdown accuracy[5] Possibility of vibration[6] Travelling performance of the carriage to get overbumps at rail joints-[A](1) Method to hold the unit can (shape of the unit can)(2) Method to store unit cans in the canister[A]-(3) Canister structure[1] Lid fastening[2] Drying[3] Degassing

Notes

To be studied by Canister
Project Team

©International Research Institute for Nuclear DecommissioningNo.166

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Verification items and methods
Verification method

No.

9Major issue

Verification items

Conceptual
Study

Element Test

(1) Change in the attitude of the robot arm during withdrawal-• Verified
last year(2) Robot arm retraction into cell (carriage travelling)(3) Access rail retraction(4) Leveling the access rail

-

[A]

Notes

[A]

Emergency escape(5) Withdrawal of the access rail into the cell

(Traction byanothercarriage isplanned.
There are a lotof proventrack recordsof traction
carriages.)-

10

Environmental resistance(1) Environment resistance (radiation, temperature, humidity,
dust and foreign matters)

[A]

-

11

Maintainability(1) Review of maintenance items(2) Review of maintenance methods[A]-©International Research Institute for Nuclear DecommissioningNo.167

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Verification iitems and methods
Verification method

No.

Major issue

Verification items

Conceptual
Study

Element
Test

12

Exchange of tip tools(1) Study of remote-controlled tool exchange methods(2) Study of tool carrying-in/carry-out methods

[A]

-

13

Feasibility of the wholeprocess(1) Performing a test to go over the whole process andidentifying issues

-

[A]

14

Throughput(1) Throughput verification

-

[A]

Notes

©International Research Institute for Nuclear DecommissioningNo.168

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Test device overview[1] Robot arm(already manufactured): 6-axis hydraulic manipulator
Reaction force of 2 tons (boring of boreholes with a diameter of about 60 mm is assumed.)
Arm length: 7.1 m (to cover the vertical access range from the RPV bottom to a level 1.5 m
below the pedestal bottom surface)[2] Access rail
: 3-section extension rail
(Carriage section is additionally manufactured) Fixed on the cell floor and to Pedestal opening for CRD[3] Test facility: cell floor and the low part of the pedestal are reproduced.
(newly manufactured)

Access rail

Robot arm

Pedestal simulant part

Carriage,
additionally built
prototype

Schematic drawing of the whole test facility©International Research Institute for Nuclear DecommissioningNo.169

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Test device overview

The robot arm and the carriage that interfaces the robot arm to theaccess rail were newly built and assembled to the access rail built
last fiscal year to complete a prototype. Combination tests wereconducted with this prototype.

Arm robot• Equipped with a coupling device for thetransfer carriage(coupled with the transfer carriage
whenever traveling)• Equipped with a mechanism that engages
with the rail and holds the position(Secured to the rail during disconnection)

Unit Canister

Additional test
production
range

Transfer carriage• Traveling on the rail driven by
the cable©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1707.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail
⚫ Test details
Prototype models of a carriage that travels on the access rail are built and subjected to operation tests that simulate the wholeprocess including the installation of the access rail using the test apparatus that reproduced the actual pedestal structure in order toverify the feasibility.
[1] Simulation of robot arms carrying in and out of the pedestal (verification of travelling performance of the carriage to get overbumps at rail joints)[2] Simulation tests of drilling fuel debris in the pedestal[3] Collection of processed fuel debris into the unit can[4] Movement of the access can during traveling on access rail (verification of travelling performance of the carriage to get overbumps at rail joints)⚫

Expected results➢ Feasibility of the whole process including the carrying-in of equipment in the pedestal, drilling of debris and removal➢ Work time to complete each step of the whole process including the carrying-in of equipment in the pedestal and theremoval of debris (excluding debris drilling time)➢ Identification of detailed issues and measures for them©International Research Institute for Nuclear DecommissioningNo.171

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Test items and criteria

No.

Test item

1

Installation of the robot arm in the access rail

2

Remotely controlled installation of access rails

3

Carrying-in of the robot arm in the pedestal(Cabling of robot arm is covered by as many workers in thiselement test)

Criteria•••

Arm robot can transit to the access rail.
Arm robot and transfer carriage can be secured.
Secured carriages shall be retained even in case of drive
source outage.

•

Installation must be possible under dark conditions by remote
operation that is guided by a camera and supported by lighting,both attached to the equipment.

••

Capable of getting over bumps at access rail joints smoothly
The attitude of the robot arm must be accurately controlled asintended by the camera-image based guiding during thecarrying-in operation into Pedestal.
Rail retention force of arm robot shall be xx or greater (Specificvalue is under study)
Arm robot shall be still secured on the rail even in case of drive
source outage.

••

4

Positioning of the robot arm during interfering object/debris
processing (drilling)5

Bearing of reaction force generated by interfering object anddebris processing (drilling)•

Positioning must be possible under dark conditions by theguidance using the image of a camera and with the support oflighting, both attached to the equipment.

•

There must be no abnormality in the operation of the robot arm
and access rail when a pressing force of 2 tons is applied to thefloor surface.
©International Research Institute for Nuclear DecommissioningNo.172

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Test items and criteria

No.
6

7

8

9

Test item

Criteria

Transportation of the unit can within the cell(traveling of the transfer carriage on the access rail)• The transfer carriage must be capable of moving
downward only by gravity.
• Capable of getting over bumps at access rail joints
smoothly

Emergency escape• Robot arm retraction (carriage travelling) into cell ispossible.
• The access rail must be retractable.
• It must be possible to level the access rail.

Feasibility of the whole process• The whole process from the carrying-in of the access rail
for the robot arm to the withdrawal of the access rail into
the cell must be able to be done by remote operation(Identify and address work that cannot be done byremote operation and find solutions for them if any).

Throughput verification• The cycle time for the whole operation must be
measured, and the throughput calculated based on thecycle time must be 10 years or shorter (Find measures if
exceeding 10 years).
©International Research Institute for Nuclear DecommissioningNo.173

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(2) Maneuverability verification by a combination of robot arm and access rail⚫

Development process
FY2017 (Heisei 29-30)

FY2018 (Heisei 30)

Items to study
4

5

6

7

8

9

10

11

Interim report


12

1

2

3

4

Annual report


5

6

7

8

9

10

11

Interim report


12

1

2

3

Annual reportKey milestones

1. Conceptual study

2. Element test plan

3. Test preparation
4. Test device
production
5. Element Tests

6. Summary©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1747.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(3) Verification of radiation resistance of robot arm hydraulic fluid⚫

Purpose of development➢ The radiation resistance of hydraulic fluid is tested, and the obtained data is used to verify the feasibility andmaintainability of robot arm.
(The radiation resistance evaluation test needs to be performed since data concerning the radiation resistance of
hydraulic fluid is not available almost at all while same data is available for other materials such as resins andelectronic devices).

⚫

Issues to be resolved➢ Oil hydraulic (flame-retardant hydraulic fluid) is assumed for robot arms instead of water hydraulic because theyrequire high output and high positioning accuracy; maintenance requirements including oil exchange frequency areunspecific due to insufficiency of radiation resistance data on hydraulic fluid.
Development approach➢ Selection of hydraulic fluid➢ Study of test and evaluation methods➢ Radiation resistance evaluation test
Test Conditions➢ Dose rate
: to be determined through discussions with the test facility studying team
➢ Cumulative dose : to be determined, example) 100, 300, 500, 750, 1,000 [kGy]⚫

⚫

©International Research Institute for Nuclear DecommissioningNo.175

7. Implementation Details
7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(3) Verification of radiation resistance of robot arm hydraulic fluid⚫
⚫

⚫

Expected results➢ Radiation resistance data of the hydraulic fluid used in the robot arm
Development status➢ Selection of hydraulic fluid
New hydraulic fluids with potential resistance to radiation are being examined in addition to the fluids used in thepast.
➢ Study of test and evaluation methods
Evaluation items in the radiation resistance test are being studied. Dynamic viscosity, oxidation, level ofcontamination, change in flash point and gas generation amount are listed.
➢ Radiation resistance evaluation test
Sample fluids will be put in test tubes or similar containers and subjected to radiation exposure according to thecurrent plan.
Development schedule

FY2017 (Heisei 29-30)

FY2018 (Heisei 30)

Items to study
4
Verification ofradiation resistanceof robot arm
hydraulic fluid

5

6

7

8

9

10

11

12

1

2

Test Plan

3

4

5

6

7

8

9

10

11

12

1

2

3

Radiation resistance evaluation test
preparation and implementation

Study of test apparatus

Summary©International Research Institute for Nuclear Decommissioning7. Implementation Details
7.2. Implementation Details

No.176
Collaborative study with
Osaka University2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(4) Development of hydraulic manipulator force control technique⚫

Development goals➢ Estimation of the force exerted to the cylinder, and the development offorce control method based on the estimate➢ Coexistence of position control and force control⚫

Issues➢ The position of the robot arm front end and the pressing force applied tofuel debris need to be controlled during the fuel debris retrieval work withthe robot arm (where reaction force generated by the activation
fluctuates while the position of the robot arm front end is held at a fixed
position, for example). No study has been made on the force control
while the position control was studied last fiscal year.

⚫

Development approach➢ Study of force estimation➢ Study of force control method➢ Estimation of force generated by the hydraulic manipulator and thecylinder, and application tests of force control
Hydraulic manipulator©International Research Institute for Nuclear DecommissioningNo.177

7. Implementation Details

Collaborative study with
Osaka University

7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(4) Development of hydraulic manipulator force control technique⚫

Development status➢

Production of test device to verify the effectiveness of the control law
A test apparatus consisting of a single-shaft hydraulic cylinder was made, which could make theverification of the control law easy.

➢

Development of a method to estimate the force exerted to the cylinder
Force estimation methods are being studied, such as force estimation using pressure and differential
pressure, and the improvement of accuracy by filter setting.
The effectiveness of a force estimation method is evaluated by measuring the force of the single-shaft
cylinder by a load cell and comparing the measured data with the actual force.

➢

Development of force control
Operation by the PI control was examined with the single-shaft hydraulic cylinder.
The control law of force control is being studied based on the result of the examination.

©International Research Institute for Nuclear DecommissioningNo.178

7. Implementation Details

Collaborative study with
Osaka University

7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(4) Development of hydraulic manipulator force control technique[1]Servo valve[3] Linear scale[4] Load cell

[2] Pressure sensor[5] Hydraulic cylinder⚫

Single-shaft hydraulic cylinder test apparatus

Development schedule

FY2017 (Heisei 29-30)

Items to study
4Study of hydraulicmanipulator force
control

5

6

7

8

9

10

11

12

FY2018 (Heisei 30)
12

Study of force estimation
ContractStudy of force control method

3

4

5

6

7

8

9

10

11

12

1

2

3

Force estimation and force
control application test
Summary©International Research Institute for Nuclear DecommissioningNo.179

7. Implementation Details

Collaborative study with
Kobe University

7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(5) Development of technique for motion planning in consideration of avoidance of interference with theenvironment of multi-degree-of-freedom robot⚫ Development goals➢ Development of methods to design the optimal motion trajectory of a manipulator within a narrow space in considerationof the avoidance of elbow interference⚫

⚫

Issues➢ It has become possible to expand the motion range in a narrow spaceby the combination of multiple robots (such as the combination of anaccess rail and a robot arm, or of an electric-powered manipulator anda weld head); however, it is assumed that access control of themanipulator in a narrow space, whose shape dynamically changes
with the progress of work, is still very difficult for operators.
Therefore, it is necessary to develop a motion planning technique formulti-degree-of-freedom robot under restraint conditions such as
interference avoidance.

X-6 penetration
simulant structure
7-axismanipulator

Testfacility

Test cradle

Development approach
Biaxial weld head
➢ Study of a method to describe intended trajectory and restraint
conditions➢ Study of a generic method to describe ambient environments
Wire reel➢ Verification test of a trajectory generated by technique for motion
planning
Wire feed guide©International Research Institute for Nuclear DecommissioningNo.180

7. Implementation Details

Collaborative study with
Kobe University

7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(5) Development of technique for motion planning in consideration of avoidance of interference with theenvironment of multi-degree-of-freedom robot⚫

Development status➢ Study of a method to describe intended trajectory and restraint conditions
This is an earlier study (2013) by Tazaki et al. of Kobe University.
"Method for trajectory planning of multi-body systems" is applied.
•Proposal of a method to plan a trajectory within a work space expressed in multibody system•Assure implementation of high priority tasks without interference from low priority tasks•Ability to move an object to an intended position with the most efficient motion
When applying the trajectory planning method directly, a trajectory that meets the following restraint conditions is
to be designed using gradient method based optimization calculation: The trajectory of the arm front end must coincide with the weld path.
 Interference between the link mechanism and the welding workpiece must be avoided.
➢

Study of a generic method to describe ambient environments
Surrounding environment is also expressed in multibody system.

©International Research Institute for Nuclear DecommissioningNo.181

7. Implementation Details

Collaborative study with
Kobe University

7.2. Implementation Details2) Element technology development for installing retrieval equipment[2] Technical development for removing interfering objects during fuel debris retrieval
c. Method for removing interfering objects by fuel debris retrieval equipment commonly used in access fromboth entries(5) Development of technique for motion planning in consideration of avoidance of interference with theenvironment of multi-degree-of-freedom robot⚫ Issues and solutions
Solutions<Example of success>Issues<Example of failure>

A solution
may not be
obtained
when aninappropriate
initial value isgiven since
the shape of
the welding
workpiece iscomplex(nonconvex).

(Arm front end
reaching point)

A proposed two step planning method that
(Arm front end position)
follows Steps [1] and [2] below via thestopover point (virtual destination) is(Elbow position)
given in advance.

(Arm front end
reaching point)[1] Formation of a temporary trajectoryMove the hand and elbow to align themwith the virtual destination.
Not consider interference avoidance.
[2] Formation of the final trajectory
Make the position of the arm front end
coincide with the weld path using the
temporary trajectory formed in [1] as an
initial trajectory.
Consider interference avoidance.

⚫

Development schedule
FY2017 (Heisei 29-30)

Items to study
4
Formation and evaluation ofa trajectory that takes into
account the avoidance ofinterference with theenvironment of multi-degreeof-freedom robot

5

6

Contract

7

8

9

10

11

12

FY2018 (Heisei 30)
12

Study of a method to describe intended trajectoryand restraint conditions
Study of a generic method to describe
ambient environments

3

4

5

6

7

8

9

10

11

12

1

2

3

Verification test of a trajectory generated by techniquefor motion planning
Summary©International Research Institute for Nuclear DecommissioningNo.182

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system[2] Development of a fuel debris cutting/dust collection system[3] Development of methods to prevent fuel debris diffusion

2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell[2] Technical development for removing interfering objects during fuel debris retrieval

3) Development of remote maintenance technologies for fuel debris retrieval equipment
4) R&D management©International Research Institute for Nuclear DecommissioningNo.183

7. Implementation Details
7.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment

Fuel debris retrieval equipment/devices and system (including the fuel debris cutting and dust collection
system, containers and work tables, monitoring system, and robot arms to manipulate these equipment) needs
to be remotely maintained as a rule by because of their installation in a high radiation area. This requires
reviewing maintenance methods for fuel debris retrieval equipment and systems, evaluating feasibility,
identifying issues, and studying a reasonable action policy with actual equipment.
Among other things, the following main themes with element tests will be performed on an as needed basis.
Through these activities, issues will be identified and reviewed.
a. Study of remote maintenance action policies in the top entry and the side entry methods in common• For the side entry methods, the basic conditions concerning maintenance tasks are under study and discussion.
• From now, the basic implementation policy of remote maintenance will be formulated with consideration of
possible workers’ intervention and workers exposure.
b. Layout of main equipment used in the top entry and the side entry methods and their traffic lines• Design conditions used in the study of cells and methods are being studied and discussed for the side entry
method.
• The first review meeting concerning three the side entry methods was held by Hot Cell & Manipulator WG.
• From now, the basic policy concerning the layout of main equipment and the traffic line of them will be formulated
in consideration of the usability of the equipment and facilities of removal work.
Technical development planning• A development plan toward the realization of fuel debris retrieval work needs to be established. For this purpose,study results will be summarized and reviewed first, followed by the identification of technical challenges
concerning the equipment and facilities of removal work.

©International Research Institute for Nuclear DecommissioningNo.184

7. Implementation Details
7.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment

Fuel debris retrieval equipment/devices and system (including the fuel debris cutting and dust collection system, containers
and work tables, monitoring system, and robot arms to manipulate these equipment) needs to be remotely maintained as arule by because of their installation in a high radiation area. This requires reviewing maintenance methods for fuel debris
retrieval equipment and systems, evaluating feasibility, identifying issues, and studying a reasonable action policy with actual
equipment.
⚫

Purpose of development➢ Demonstrate feasibility as a maintenance "system" through the consistent point of view⚫

Issues to be resolved➢ Although some equipment will be maintained, the feasibility of a maintenance plan as a system is doubtful because themethods proposed for individual equipment lack consistency (selection of remote/direct, maintenance space or rooms
and equipment to be maintained).
➢ When considering the above status, the current plan’s feasibility concerning the construction and layout of equipment is
not certain.

©International Research Institute for Nuclear DecommissioningNo.185

7. Implementation Details
7.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment⚫

Development approach➢ Establish the point of view of maintenance (including selection of remote/direct and maintenance space or rooms)
taking the 1st floor remote maintenance as a basic policy.
•
Define areas that workers enter.
•
Sort maintenance work into two groups clearly: those that can be performed remotely and those cannot.
➢ Equipment layout and traffic lines in the cell are designed with consideration of maintenance.
➢ Technologies necessary to realize the maintenance system are developed. (Only drawing up a development plan inthis project)⚫

Expected results➢ Basic maintenance policy of equipment in the cell (proposed)•
Access classification•
Maintenance classification, etc.
➢ Equipment layout in the cell
➢ Technical development plan

©International Research Institute for Nuclear DecommissioningNo.186

7. Implementation Details
7.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment⚫

Method of study
The following approaches are taken to studying remote maintenance technologies applicable to fuel debris retrieval
equipment:➢ Existing remote maintenance technologies are referred to as the base of the study.
➢ The scope of the study is technologies necessary to perform the remote maintenance of equipment in the primaryboundary (inside the cell).

⚫

Input before study⚫

➢

Worker exposure control value➢

Environmental condition: atmospheric dose rates and radioactivity concentrations in R/B and in the extension building➢

Restrictions to cells in R/B: height, weight, etc.

Study flow

Survey of remote
maintenance records

Set worker accessconditions for 1F

Study of basic
maintenance policy(proposed)

Study of maintenanceplan for equipment in
the cellStudy of work process
in the cell

Set equipment usage
environmental
conditions for 1F
Conceptual study ofremote maintenancefacilities andequipment

Study of layout andlaydown in cell

Development planning©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1877.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment⚫

Study status[Maintenance methods and approach]

Master-slave
manipulator

Remote maintenanceShield hatch

Controlroom

OutsideCell

Shield observation window

InsideCell

Equipment tobe maintained

OutsideCell

InsideCellto transfer destination
Freeze valve

Green house
Inlet

On-site control
panel

Tanks

Nitrogen
supplyMaintenance Cell

ITV camera &light

Master-slave
manipulator

OutsideCell

Move[Maintenance classification]•
Regular maintenance•
Emergency maintenanceIn-cell craneEquipment tobe maintained
Shield window

Direct maintenance
Remote + on-site
maintenanceShield door

Power manipulator

OutsideCell Remote operation
 Mobile remote operation
system Operation andcontrol••

InsideCell

ITV camera& light[1] Survey on record of remote maintenance•In-cell craneShield door

Air lift pump
Power manipulator
Equipment tobe maintained

Shield door

Inside Cell

Place to be maintained

Cited from the case example booklet of regular maintenance work in Rokkasho
Reprocessing Plant
http://www.jnfl.co.jp/cycle-recycle/re_siken-tandt/pdf/re_siken-tandt3.pdf©International Research Institute for Nuclear DecommissioningNo.188

7. Implementation Details
7.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment[2] Set worker access conditions for 1F[Contamination classification]•
Inside of the primary boundary was segmented based on the contamination classification until last fiscal year.
Contamination
classification

Definition ofarea

High-level contaminated area(Red)

Mid -level contaminated area
(Yellow)

Low-level contaminated area
(Green)Area where radioactive
materials are handled directly
without covering

Area where radioactive
materials are put in a sealedcontainer for handling

Area where radioactive
materials are put in a sealed(tightly sealed) container forhandling

Area where radioactive
materials are put in a sealed(tightly sealed) container forhandling

In normal conditions, a highlevel of contamination exists

There is a possibility of a highlevel contamination due toradioactive materials in thehigh-level contaminated area

The possibility of a high level ofcontamination is very low.

There is no possibility of a highlevel of contamination.

Target Control
Value

Outside Cell

To be determined[Dose classification (proposed)]•
Dose classification is defined to set areas workers are permitted to enter for maintenance in addition the contamination
classification.
Doseclassification

Definition of area

Target Control
Value

High radiation area

Intermediate dose area

Low dose area

Outside Cell

Area where radioactive materials
are handled without shielding

Area where radioactive materials(excluding contaminated ones) arehandled by shielding them

Area where radioactive materials(excluding contaminated materials)
are put in a shielding container forhandling

Area where radioactive materials(excluding contaminated materials)
are put in a shielding container forhandling

Radioactive materials cause an
extremely high dose rate

Contamination causes high dose
rates despite shielding

The dose rate is low becauseradioactive materials are put in thecontainer, and the level of thecontamination of the shielding
container is also low.

The dose rate is almost negligible
except that in the background.

To be determined©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1897.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment[2] Set worker access conditions for 1F[Worker access classification (proposed)]•Every part in the primary boundary is segmented according to contamination and dose categories (shown in the upper column).
•
Worker access classification was set in each area (shown in the lower column)
Dose classification

High radiation area

Intermediate dose area

Low dose area

Outside Cell

Contamination
classification
High
Contamination
Area
(red)
MediumContaminationArea(yellow)⚫
⚫

Inside the PCVInside Cell (Red)(during operation)⚫

Inside Cell (Yellow)(during operation)

⚫

D*2

D
⚫

Inside Cell (Red)(duringmaintenance*1)⚫

Inside Cell (Yellow)(duringmaintenance*1)⚫

Inside Cell (Red)(duringmaintenance*1)
D*2-

Inside Cell (Yellow)(duringmaintenance*1)

-

C

-

D

C

Low
Contamination
Area(green)

- *3

- *3

D

C

B

-

Outside Cell

-

-

-

A

[Worker access classification]
D : entry is not permitted at any time, including emergencies
C : During an emergency, short-time access by workers is assumed
B : In normal conditions, short-time access by workers is assumed
A : In normal conditions, access by workers is assumed

*1:
*2:
*3:

⚫

Inside the cell (green)-This classification is subject to the condition that there are no radioactive materials in the area except forcontaminated objects or radioactive materials are put in a shielding container during maintenance.
Measures to enable the worker entry in an emergency need to be prepared. However, maintenance methods must
be designed based on the premise that worker entry is forbidden.
At present, there is no area that falls into these segments since it is planned that only radioactive materials stored ina shielding container are handled in the low-level contaminated area.
©International Research Institute for Nuclear DecommissioningNo.190

7. Implementation Details
7.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment[3] Establish equipment usage environmental conditions for 1F[Worker access classification (proposed) and equipment usage environment]
[13]

[12]

[11]

[5]
[7]

[3]

[10]

[10]
[6]

[8]
[4]

[2]

[1]

B: In normal conditions, short-time access by workers
is assumed
C: During an emergency, a short-time access by workers is
assumedD: entry is not permitted at any time, including emergencies. However,measures to enable the worker entry in an emergency need to beprepared.
D: entry is not permitted at any time, including emergencies
Examples of equipment to be maintained (See the list on the right)

Examples of equipment to be maintained:[1] Equipment used in PCV[2] Equipment permanently installed in the cell (red)[3] Material handling equipment between cells (red cell and yellow cell)[4] Equipment permanently installed in the cell (yellow)[5] Material handling equipment between cells (yellow cell and green cell)[6] Equipment permanently installed in the cell (green)[7] Material handling equipment between the cell (green) and outside cells[8] Door between the cell (red) and the cell (yellow)[9] Door between the cell (yellow) and the cell (green)[10] Door between the cell (green) and outside cells[11] Opening between the cell (red) and the cell (yellow)[12] Opening between the cell (yellow) and the cell (green)[13] Opening between the cell (green) and outside cells©International Research Institute for Nuclear DecommissioningNo.191

7. Implementation Details
Hydraulic jack for theaccess rail retraction

7.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris
retrieval equipment
a. A study of remote maintenance action policies in the top entry andthe side entry methods in common
b. Layout of main equipment used in the top entry and the side entry
methods and the traffic line of them

Tool rack
Manipulator

Unit can inspection chamberContaminatedwater pipe

Empty unit can storage area
Mini-Cask System
Canisterconnecting door
Transfer carriage
airlock

Shield door to PCV

Expected functions of fuel debris retrieval cell•
Pull out empty unit cans from the canister in the mini cask.
•
Hold empty unit cans (4 units) and supply them to the access rail.
•
Receive unit cans loaded with fuel debris from the access rail and put
them in the canister in the mini cask.
•
Material accountancy of unit cans containing collected fuel debris(including weight and radiation dose).
•
Supply utilities to the robot arm and access rail.
•
Robot arm tip tools for exchange: Four tools stored.
•
Supply tools for exchange to robot arm for exchange and support
exchange task.
•
Receive wastes (other than fuel debris) that were removed frominside PCV from the access rail and transfer them to the maintenancecell.
•
Carry in/out robot arm and access rail between the maintenance celland PCV.

Technical development planning•
A development plan toward the realization of fuel debris
retrieval work needs to be established. For this purpose, study
results will be summarized and reviewed first, followed by theidentification of technical challenges concerning the equipment
and facilities of removal work.

Load distribution
base plate
Crane cable pair
Large equipment
carrying in/out route
Equipment and waste
carrying in/out route

Shield door
for crane
Shielddoor

Manipulator

Transfer carriage rail

Winch for access rail retraction
Low-level radiation wastechamber storage area
Shield wall
Access rail cable pair

Canister transfer carriage
Fuel debris carryingin/out route

Crane©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1927.2. Implementation Details
3) Development of remote maintenance technologies for fuel debris retrieval equipment
FY2017 (Heisei 29)

FY2018 (Heisei 30)

Items to study
4

Key milestones

5

6

7

8

9

10

11

Interim report


12

1

2

3

4

Annual report


5

6

7

8

9

10

11

12

1

2

3

Interim reportAnnual report

1. Conceptual study
2. Study of specificproposal for fueldebris retrieval
3. Review and analysisof study results

4. Element tests

Element tests are performed where necessary

5. Wrap-up

Notes

Expected results[1] Basic maintenance policy of equipment in the cell (proposed)⚫ Access classification⚫ Maintenance classification, etc.
[2] Equipment layout in the cell[3] Technical development plan
©International Research Institute for Nuclear DecommissioningNo.193

7. Implementation Details
7.2. Implementation Details
1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system[2] Development of a fuel debris cutting/dust collection system[3] Development of methods to prevent fuel debris diffusion

2) Element technology development for installing retrieval equipment[1] Element technology development related to work cell[2] Technical development for removing interfering objects during fuel debris retrieval

3) Development of remote maintenance technologies for fuel debris retrieval equipment
4) R&D management©International Research Institute for Nuclear DecommissioningNo.194

7. Implementation Details
7.2. Implementation Details4) R&D management[1] Human resource development from a mid- and long-term viewpoint
It is planned to send staff to human resources development forums and international decommissioning
workshops from the viewpoint of the development of human resource that will be necessary in a mid- to longterm range.
The described below is one of the results:* IRID Symposium 2017 in Iwaki
Date and time: August 3 (Thursday), 2017 13:00-16:45
Place: 120 Taira-tamachi (Aza), Iwaki-si, Fukushima Iwaki Business Innovation Center, Exhibition Hall
(LATOV 6F)[2] Consulting experts inside and outside Japan
Technologies and expertise were gathered from Japanese and global vendors. The described below are theresults:
VendorServices

Reason of adoption

IHI

Element tests for sealing design
applicable to the side entry method
Tests of methods to remove
interfering objects outside Pedestal

Plan-B2 was developed in collaboration with IHI as a the side entry method andcompleted last fiscal year. It was adopted as one of the side entry methods. In
addition, IHI has thorough knowledge of the plant before it was hit by theearthquake so that they deserve to undertake the study of interfering object
removal methods and relevant element tests.

PaR Systems

Element tests of cutting and dust
collection of fuel debris (ultrasonic core
boring)Ultrasonic core boring is one of promising technologies for fuel debris
processing. Jet Propulsion Laboratory (JPL), a U.S. company, owns thefundamental technology. Technology development is planned based on theframework where PaR Systems designs an integrated system (equipment andfacilities) that can be applied to the condition of the 1st floor.

©International Research Institute for Nuclear DecommissioningNo.195

7. Implementation Details
7.2. Implementation Details4) R&D management[2] Consulting experts inside and outside Japan (continued from the previous slide)
Technologies and expertise were gathered from Japanese and global vendors. The described below are theresults:
VendorServices

Reason of order

AREVA NC

Study of cell design

AREVA has proven experience in fuel debris retrieval work at TMI and indecommissioning. It also operates a nuclear fuel reprocessing plant in La Hague, France.
Based on those experiences, it has ample track records especially in the design,
production, and operation of a hot cell.

Kajima Corporation

Conceptual study ofsoundness of reactor building

Kajima Corporation designed and built Units 2 and 3 reactor buildings of Fukushima
Daiichi Nuclear Power Station; they have enough knowledge, technical information, andknow-how for conceptual design study that is performed to assure the soundness of thereactor building, which additional loads will be exerted by the preparation of fuel debris
retrieval using the partial submersion-the side entry method.

Osaka University

Study of hydraulic manipulator
control methods

Osaka University has research achievements on various types of robot control along with acopious knowledge of the hydraulic control of machinery, such as construction machinery.

Kobe University

Evaluation of a trajectoryformation that takes into
account the avoidance ofinterference with theenvironment of multi-degreeof-freedom robot

Kobe University has a proven tracked record in interference avoidance using the elbow ofmulti-degree-of-freedom robot in IRID Decontamination Robot program in FY2013 and2014. They also have knowledge of interference avoidance technology applicable to workin a narrow space where avoiding interference is essential.

©International Research Institute for Nuclear Decommissioning7. Implementation Details

No.1967.2. Implementation Details4) R&D management[3] Cooperation with other R&D activities such as those for decommissioning work
It is being discussed with other R&D project teams how to utilize results for the decommissioning
project in practical ways. Key cooperative conferences are listed below:◼ April 27, Thursday, 2017: Meeting with the development team working on enhanced
methods/systems and sampling technology
Achievements of the previous project and project approaches were shared.
◼ June 22, Thursday, 2017: Meeting with the development team working on enhanced
methods/systems and sampling technology
Contents of optimization study and information of project progress were shared.
◼ August 24, Thursday, 2017: Meeting with the development team working on enhanced
methods/systems, sampling technology and criticality control technology
Information about a risk of criticality during fuel debris processing was shared.
◼ October 26, Thursday, 2017: Meeting with the development team working on enhanced
methods/systems and sampling technology
Information about sampling needs was shared.
◼ February 20, Tuesday, 2018: Meeting with the development team working on enhanced
methods/systems, sampling technology and PCV internal investigation technology
Needs of detail investigation were identified and information about the needs was shared.

©International Research Institute for Nuclear DecommissioningNo.197

7. Implementation Details
7.3 Coordination of Sharing operators[1] Coordination status of sharing operators
Operators listed in the table below submitted their interim reports so as to share results of the previous projects
at:◼ Sharing Operator Interim Report Meeting◼ Date and time: September 7 (Thursday), 2017 13:30-18:00◼ Place: Office of Government-led R&D Program on Decommissioning and Contaminated Water Management[2] Analysis of tasks implemented by sharing operators
Below table shows IRID analysis results of tasks to be implemented by sharing operators in this project:
No.

Sharing operators

Project Items

Implementation item analysis result1

Hamamatsu Photonics
K.K.

Development of monitoring
technology during fuel debris
retrievalTechnical advancement can be expected
because the development plan set specifictechnological targets, such as improving
radiation resistance and downsizing
cameras.

2

COMEX NUCLEAIRE

Development of fuel debris
cutting and dust collection
systemTechnical advancement can be expected
because the development plan includes
specific ideas such as a dust collection
system and its scale, not to mention theperformance of laser processing.

Notes©International Research Institute for Nuclear DecommissioningNo.198

8. Overall Summary(1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection system➢ The distribution and characteristics of fuel debris were studied in cooperation with the Fuel
Debris Characterization Project team.
➢ Study of a retrieval system is underway based on the results of the above-mentioned study.
[2] Development of a fuel debris cutting/dust collection system➢ Prioritized processing technologies to be developed based on the distribution andcharacteristics of fuel debris.
➢ Element tests on processing and dust collection are planned.
[3] Development of methods to prevent fuel debris diffusion➢ A conceptual study of measures to prevent the diffusion of fuel debris during processing isbeing performed.
➢ Element tests on fuel debris diffusion prevention are planned.
(2) Element technology development for removal equipment installation[1] Element technology development related to work cell

➢ Based on the study results in the project for upgrading of approach and systems for retrievalof fuel debris and internal structures, hypothetical design conditions were set for work cellstudy.
➢ Elemental tests of the inflate seal are planned.

©International Research Institute for Nuclear DecommissioningNo.199

8. Overall Summary(2) Element technology development for removal equipment installation (continued)[2] Technical development for removing interfering objects during fuel debris retrieval➢ A conceptual study on the throughput of interfering objects removal work is being
performed.
➢ Interfering objects that need to be removed to enable fuel debris retrieval were identified.

➢ Element tests are planned for interfering object dismantlement especially for elements that
require more to develop.
(3) Development of remote maintenance technologies for fuel debris retrieval equipment➢ Based on the study results in the project for upgrading of approach and systems for retrieval offuel debris and internal structures, hypothetical design conditions concerning remote
maintenance technologies such as area segmentation were set.
➢ A conceptual study of remote maintenance technology is being performed based on the above
hypothetical conditions.
(4) R&D management➢ Human resource development from a mid- and long-term viewpoint was facilitated by holding
IRID symposiums, for example.
➢ Technologies and expertise were gathered from Japanese and global vendors.

©International Research Institute for Nuclear Decommissioning9. Specific Goals to Achieve Implementation Objectives

No.200(1) Technical development for prevention of fuel debris diffusion[1] Development of a fuel debris collection
systemFuel debris removal and conveyance methods and work steps to implement them, eachof which are effectively applicable to different forms of fuel debris (such as solidfragments, polluted mud, and fine powders), shall have been identified through study andelement tests for removal methods and systems applicable to different forms of fueldebris and for conveyance and storing systems to move collected fuel debris into thecanister.
(Target TRL upon completion: Level 3)[2] Development of a fuel debris cutting/dustcollection system• Cutting and grinding elemental tests

With respect to the cutting technology, basic workability shall have been verified byelement tests. In addition, newly identified issues shall have been addressed andimproved as development themes continued from the base technology development
project in the previous fiscal year.
The performance of dust collection technology shall have been demonstrated throughdust collection tests performed along with processing.
(Target TRL upon completion: Level 3)• Crush-with-chisel element tests

The basic workability shall have been verified mainly through processing tests of fueldebris in the PCV bottom. In addition, the performance of dust collection technology shallhave been demonstrated through dust collection tests.
(Target TRL upon completion: Level 3)• Ultrasonic core boring

Applicability of ultrasonic core boring to fuel debris retrieval shall be evaluated. Data ofprocessing performance, and the amount and particle size distribution of dust it
generates, shall have been obtained though processing tests with fuel debris simulant
test blocks if the evaluation result is positive.
(Target TRL upon completion: Level 3)[3] Development of methods to prevent fueldebris diffusion• Element tests for diffusion prevention
from jet deflectors

The basic feasibility of the technology to prevent fuel debris diffusion through jet
deflectors shall have been verified by the element tests.
(Target TRL upon completion: Level 3)©International Research Institute for Nuclear Decommissioning9. Specific Goals to Achieve Implementation Objectives

No.201(2) Element technology development for removal equipment installation[1] Element technology development related towork cell• Structure study/installation method study• Inflate seal elemental test

[2]Technical development for removing
interfering objects during fuel debris retrieval

The conceptual study on the possibility of work cell installation and ease of handlingshall have been performed. Effective remote-controlled installation methods shallhave been identified, along with accompanying issues, and the action policy toaddress the identified issues shall have been clarified.
(Target TRL upon completion: Level 3)
Applicability of inflate seal to build a boundary shall be evaluated.
If the applicability is recognized, conduct an element test for sealability of inflate seal
and evaluate the seal performance. In addition, element tests of the remotecontrolled inflate seal exchange method shall have been performed and the feasibilityof the method be verified.
(Target TRL upon completion: Level 4)

The study and element tests of remote-controlled removing methods applicable toobjects that block the access route to fuel debris and need to be removed shall havebeen performed. Through these activities, effective interfering objects removing
procedures, and methods and facilities and equipment to execute them, shall havebeen identified along with accompanying issues, and the action policy to address theidentified issues shall have been clarified.
(Target TRL upon completion: Level 3)• Interfering objects that block access from top
entry (such as dryer and separator)

Feasibility of basic procedures and methods for removing interfering objects shallhave been verified by producing full-scale mock-ups to simulating interfering objects.
(Target TRL upon completion: Level 4)• Interfering objects that block access from side
entry (Equipment outside the pedestal)

Feasibility of basic procedures and methods for removing interfering objects shallhave been verified by producing full-scale mock-ups to simulating interfering objects.
(Target TRL upon completion: Level 4)©International Research Institute for Nuclear Decommissioning9. Specific Goals to Achieve Implementation Objectives

No.202(2) Element technology development for removal equipment installation• Structures in the reactor building (PCVwall boring)

Feasibility of basic procedures and methods for removing interfering objects shall havebeen verified by producing full-scale mock-ups to simulating interfering objects.
(Target TRL upon completion: Level 4)• Interfering objects that block both top
entry and side entry(RPV bottom part, equipment in thepedestal)

Feasibility of basic procedures and methods for removing interfering objects shall havebeen verified by producing full-scale mock-ups to simulating interfering objects.
(Target TRL upon completion: Level 4)•Verification of the maneuverability of arobot arm and access rail combined
mechanism

The feasibility of basic mechanical motion concerning interfering object dismantlement andfuel debris retrieval shall have been verified through the test that simulates the motion of arobot arm and access rail combined mechanism.
(Target TRL upon completion: Level 4)(3) Development of remote maintenance technologies for fuel debris retrieval equipment• Study of maintenance method

The conceptual study on the layout plan and traffic line of main devices and equipment used
for fuel debris retrieval work shall have been performed.
The basic evaluation of the feasibility of maintenance methods that are applied to devices
and equipment used for fuel debris retrieval work shall have been performed along with theidentification of issues, and the action policy to address the identified issues shall have beenclarified.
(End time target TRL: Level 3)©International Research Institute for Nuclear Decommissioning