Subsidy Project of Decommissioning and Contaminated Water Management
Started From FY2021

Development of Technologies for Containing,
Transfer and Storage of Fuel Debris(Drying Technology for Fuel Debris)Interim Report for FY2021

August 2022
International Research Institute for Nuclear Decommissioning(IRID)All rights reserved.
©International Research Institute for Nuclear Decommissioning (IRID)

No.1

Contents
1. Background and purpose of the project
2. Goals
3. Implementation items, their correlations, and relations with otherresearch
4. Implementation schedule
5. Project organization
6. Implementation details
6.1 Drying treatment methods such as types of objects to be dried anddrying form, and the expansion of operational parameters
6.2 Concepts of drying equipment and the expansion of data required
for setting operating conditions
7. Summary
Reference materials©International Research Institute for Nuclear Decommissioning1. Background and purpose of the projectNo.2- Background
For the types and sizes of the fuel debris to be dried, the properties of the fuel debris (moltenmaterials, Molten Core Concrete Interaction (MCCI), metallic debris and unmelted fuel assembly, etc.),
porosity, volatile Fission Product (FP) release rate, primary element composition, etc. can all affect thedrying treatment. The drying form and method can also be assumed to affect the drying treatment.
Under the subsidized project conducted in FY2019 to 2020, zeolite was used as a test piece of fueldebris assuming that fuel debris is porous based on the results of the TMI-2 accident. As for the drying
equipment, with the aim of drying fuel debris in drying chambers that still contains the unit cans withmesh structure, hot air and decompression drying methods were studied from the viewpoint of an offgas treatment for the fine particle fuel debris that accompanies the exhaust gas, while certain
operations such as stirring processing are effective to promote drying. Based on those studies,assuming that objects are dried under conditions where the objects stand still as possible from theperspective of suppressing the range of contamination, data on the objects to be dried will be
expanded by element tests and the applicability of the canister form will be examined in the full-scale
test.

- Purpose
This project aims to develop technology for containing, transferring and storing fuel debris applicableto the actual situations of the Fukushima Daiichi Nuclear Power Station on the basis of therequirements and information provided from related projects to this project (input conditions) as well as
information from this project to the related projects (output conditions), which are adjusted and set incooperation with the projects.

©International Research Institute for Nuclear Decommissioning1. Background and purpose of the project(FY2021 decommissioning R&D plan)

No.3➢ Retrieved fuel debris needs to be collected, transferred, and stored in a safe, reliable and effective manners.
➢ When fuel debris contains moisture, hydrogen gas would generate due to radiolysis.
➢ There is a trade-off between ensuring confinement during transfer and storage and venting as a measure toprevent hydrogen explosion, but the drying treatment to remove moisture are expected to act as a means to
reduce such risks.
➢ A method for drying objects under the condition of stored state in the canister is more effective for direct
drying treatment. To realize the method, data will be expanded and optimum operating conditions will beconsidered under this project.
(Target schedule) B3④ Development of Technologies for Containing, Transfer, and Storage of Fuel Debris

Item/FY
Major events in the current
Mid-and-Long-Term
Roadmap

Stage 2 (Period until the start of fuel debris
retrieval)Stage 3-①
2023 onwards

Maintain and manage safe plant conditions▽ Start of fuel debris retrieval for the initial unit
Engineering for containing, transfer, and storage[Development of Technologies
for Containing, Transfer, andStorage of Fuel Debris]

Planning

0. Investigations into containing,transfer, and storage andresearch and development
planning
Studies of canister

Update plans based on related projects, etc.

1. Development of collecting
technology(Conducted in FY2020/21)

specifications andconducting mockup verification test

2. Development of drying
technology

Development ofparameterstechnology for drying
treatment
Investigation of cases and analysis, organization,and comparison of knowledge and information,

3. Investigation of cases ofhandling radioactive
materials in powder, slurry,or sludge form (Conductedin FY2020/21)
Development of transfer
technology[Development of Technology
for Further Increasing theRetrieval Scale of Fuel Debris
and Reactor Internals] etc.

Canister filter failure scenario selection

Study of countermeasures against changes
to canister filter performanceand consequence assessment
Expansion and enrichment of drying treatment methods and operational

Clarification of issues in the dry storage of fueldebris in powder, slurry, or sludge form using
current canisters
Hydrogen gas generation
tests and investigation oftransfer conditions

Verification, etc. of dry storage
with current canisters

Alignment with related technological developments

Field work (including engineering)
R&D©International Research Institute for Nuclear Decommissioning

Team Meeting for Countermeasures for Decommissioning and Contaminated Water Treatment / Secretariat Meeting(86th meeting) Materials “FY2021 Decommissioning R&D Plan,” Added to “(Target schedule) B3④: Development ofTechnologies for Containing, Transfer, and Storage of Fuel Debris”

1. Background and purpose of the project
Excerpt from “Subsidy Project of Government-led R&D Program on Decommissioning
and Contaminated Water Management in the FY2018 Supplementary Budget(Development of Technologies for Containing, Transfer, and Storage of Fuel Debris)”
Final Report FY2020 (June, 2021)

The process of collecting, transferring, and storing fuel debris isshown below.

No.4

1. Background and objectives of the research
1.3 Considerations to date and remaining issues (1/4)

The process of collecting, transferring, and storing fuel debris and issues with the process are shown below.
Reactorbuilding<Area classification>
Red: High contamination area, Unmanned operations (remotely operated from outside the area)
Yellow: Area with medium radiation level (radiation level is controlled, but there is still a risk of harmful exposure)
Unmanned operations (remotely operated from outside the area in principle with limited occasions of workers
working in it for maintenance and tasks.)
Green: Low contamination area (not substantially contaminated),Manned operation

An example of fuel debris handling flow in the side-access retrieval method

Addition

Lifting machine

Manipulator

Lifting machine

Fuel debris treatment
cell

Fuel debris
retrievalequipment

Task
monitoring
cameraFuel debris

Access tunnel

UC transfer system

Inside thereactorAccess tunnel
Area

Safety design

Black: items that do not require
Canistertechnological development
based on past achievements,
Sub-criticalityetc.
Blue: items in which studies
Heat removal
completed (and succeeded in
the project at the actual site)
Brown: items to be terminated for
Confinement
studies in this subsidized project(and succeeded in the project at
the actual site)
Red: items that require continuous
Shieldingstudy (items to be studied in a
succeeding subsidized project orsuggested to be so)
Structure
Numbers in parentheses
indicate the chapters that
Material
describe each subject in detail

Canister lid fastening system(conducting surface
contamination inspections)

Port

CanisterDryingapparatus

Lifting machine

Sealing cellGas injection
systemTarget drying process
Primary lid
fasteningequipment /Gas injection
system / LeakdetectionsystemSecondary lid
fastening equipment Preparation/ Gas injection
cellsystem / Leakdetection system

Transfer truck

Drying equipment

Canister transfer system

The drying apparatus and theinside of the canister areclassified as an area with highradiation level

Debris treatment cell

Sealing cell
Sub-criticality can be maintained by thegeometric shape of canisters

Canisters can be naturally cooled downusing regular in-cell ventilation
Sealing materials for canisters (6.2) / Study offilters (6.2) / Confinement in the sealing cell(gas discharge is controlled)

Shielding in the sealing cell

Weight measuring system(Conduct a surface
contamination inspection)

Transfer
cask

Transfer cask transfer system

Transfer rack

Inside the[Issues]
Preparation cell
Sealing cell
premise◆ Countermeasuresfor hydrogen generation that can
Preparation cell (excluding
dryingInside the premise
equipment)be
implemented
duringtransferof airtightSub-criticality can be maintained by the geometric shape of canisters andtheirarrangement
withinthetransfercask
Natural cooldown using the containers.
building
Natural cooldown by the outside air isventilation is possible while still ⇒in Dryingpossibletreatment
while still in transfer
tocasks
reduce moisture content
transfer casks
Study of sealing materials for canisters
Study of sealing materials for canistersrate(6.2) / Study of filters (6.2) / Confinement(6.2) / Study of filters (6.2) /in the preparation cell (gasisConfinementin transfer
casksthat(gas enables airtight◆ discharge
Achievinga drying
level
controlled)discharge is controlled)containers Shielding
for upin transfer
to 7 days
Shielding in the preparation cellcasks

Study into maintaining safety functions against damage caused by a fall of up
to 9 m or the canister falling within the transfer cask (6.2)

Can respond to incidents duringtransfer (designed to be enveloped ina fall)Safety functions can be maintained against deterioration from aging (examinations of corrosion based on metalmaterials. Neutron flux density is small and irradiation has no effect)- Study of vent diameter for discharging from the filtered vent on a canister to the cell (6.2) / Ventilation
Note: Safety design and handling- Drying to seal canisters or transfer casks forcan suppress hydrogen concentration levels in the cell to less than the lower explosion limit
for “inside the reactor ~ fuelup to 7 days (6.3)- Study into reducing the moisture content rate of fuel debris via early drying of fuel debris fordebris treatment cell” was- Study of methods to predict hydrogen
Hydrogencountermeasures for hydrogen generation during sealed transfer (the timing of drying in the fuel debris
generation during transfer (via evaluation
examined in the project fortreatment cell is the first priority) (6.3)
formulas) (6.3)
further increasing retrieval- Study into measuring hydrogen concentration levels inside the transfer cask to ensure that hydrogenStudyof recombination catalyst (6.3)
Note: RPV (abbreviation forconcentration levels during transfer are 4 vol% or less (6.4)
Reactor Pressure Vessel)
PCV (abbreviation for
An inert atmosphere can be maintained in the sealing cell, preparation cell, and transfer cask
Fire prevention
Primary Containment
Remotetransportationand lid fastening are possible
Can be transported remotely
Vessel)Can be contained in transfer casks
Ease of handling
UC (abbreviation for Unit
Enlarge the inner diameter of the canister to
Improved
collection
Can)No
improve collection capability

Handling processes for fueldebris in particle or lump form

capability©International Research Institute for Nuclear Decommissioning

No.5

2. Goals
The indicators to determine achievement goals at the end of FY2022 are
as follows.
TRL: Technology readiness level
No.

Indicators for determining development goals

1

Drying data for difficult-to-dry slurry, sludge, and concrete must be prepared(Target TRL upon completion: Level 4)

2

The advantages and disadvantages of drying while material is inside the canistercompared to the chamber method must be organized(Target TRL upon completion: Level 4)3

Proposals for effective operating methods for porous media in a canister must bepresented(Target TRL upon completion: Level 4)4Requirements (requests) for canisters on the drying treatment side must beorganized(Target TRL upon completion: Level 4)©International Research Institute for Nuclear Decommissioning3. Implementation items, their correlations, and relations withother research

No.6

3.1 Drying treatment methods such as types of objects to be dried and drying form, and the
expansion of operational parameters[Details in the solicitation information]
Analytical evaluation and tests for confirmation and verification are used to select the drying form and drying methods
suitable for the types and sizes of fuel debris to be dried. The same analytical evaluation and tests for confirmation andverification are used to expand operational parameters.
Additionally, the storage form will also be considered by reviewing both individual drying of unit cans and canisters aswell as simultaneous drying of them, which is considered useful for the scale of equipment and to ensure throughput.
Requests for changes or improvements to the current structure or specifications of unit cans and canisters required for the
drying treatment will be summarized as needed for the selected drying technology.

Details of implementation* The items following “Additionally” will be considered in Section 3.2① Types of materials to be dried and expansion of data
Assumed objects to be dried include difficult-to-dry materials such as slurry andsludge, considering the variety (properties and size) of fuel debris and its processedmaterials. Furthermore, the element tests or analytical evaluation were to understandthe drying characteristics of each material to be dried and data on drying levels, drying
times, etc. will be expanded.
[Results](1) Data on the drying characteristics of slurry and sludge (element test)(2) Data on the drying characteristics of concrete (element test)©International Research Institute for Nuclear Decommissioning3. Implementation items, their correlations, and relations withother research

No.7

3.1 Drying treatment methods such as types of objects to be dried and drying form, and the
expansion of operational parameters[Details in the solicitation information]
Analytical evaluation and tests for confirmation and verification are used to select the drying form and drying methods
suitable for the types and sizes of fuel debris to be dried. The same analytical evaluation and tests for confirmation andverification are used to expand operational parameters.
Additionally, the storage form will also be considered by reviewing both individual drying of unit cans and canisters as wellas simultaneous drying of them, which is considered useful for the scale of equipment and to ensure throughput.
Requests for changes or improvements to the current structure or specifications of unit cans and canisters required for the
drying treatment will be summarized as needed for the selected drying technology.

Details of implementation* The items following “Additionally” will be considered in Section 3.2② Study of the applicability of drying methods
Based on the expanded test data, the applicability of drying treatment methods
devised in subsidized projects so far was evaluated. For those materials to be dried thatare difficult to be applied, prospective treatment methods and processes that can beconsidered as alternative candidates were also be proposed.
[Results](1) Range of application for drying concepts devised in subsidized projects (materials tobe dried)(2) Alternative treatment methods and processes when such concepts are hard to applyon the material to be dried©International Research Institute for Nuclear Decommissioning3. Implementation items, their correlations, and relations withother research

No.8

3.2 Concepts of drying equipment and the expansion of data required for setting operating
conditions[Details in the solicitation information]
The results of conceptual studies for drying equipment, facilities, and systems devised in subsidized projects to date will
be actualized and the various data required for the setting of operating conditions will be expanded. The concepts fordrying equipment, facilities, and systems that can adapt to differences in fuel debris properties (molten debris, MCCI
debris, metal debris, unmelted fuel assembly, etc.), porosity, and volatile FP release rate will be studied and actualized.
Additionally, the conceptual studies on the equipment, facilities, and systems for drying treatments that dry unit cans andcanisters individually or in groups will also be conducted. Furthermore, for the concepts of equipment, facilities, andsystems for the drying treatment that have been studied, the optimum operating conditions (range) from the viewpoint ofconformity with safety requirements will be studied and proposed. Based on these results, the qualitative evaluation ofadvantages and disadvantages will be made from the viewpoint of conformity with safety requirements, conformity withthe required throughput, the required site area, construction period, operations (frequency and duration of checks,
inspection, and maintenance, the necessity and range of decontamination, replacement frequency of parts, etc.), and soforth.

Details of implementation① Expansion of data for the canister form
A drying test plan Note 1 for the effective canister form (effective for suppressing therange of contamination) was proposed and the drying treatment using full-scale
canisters was conducted. In addition, drying levels, drying time, etc. were verified andthe applicability of drying treatment using the canister was evaluated.
[Results](1) Results of verification tests for the canister form
Note 1: Includes modifications of the full-scale test equipment manufactured in subsidized projects©International Research Institute for Nuclear Decommissioning3. Implementation items, their correlations, and relations withother research

No.9

3.2 Drying equipment concept and the expansion of data required for setting operating
conditions[Details in the solicitation information]
The results of conceptual studies for drying equipment, facilities, and systems devised in subsidized projects to date will be
actualized and the various data required for the setting of operating conditions will be expanded. The concepts for drying
equipment, facilities, and systems that can adapt to differences in fuel debris properties (molten debris, MCCI debris, metal
debris, unmelted fuel assembly, etc.), porosity, and volatile FP release rate will be studied and actualized. Additionally, theconceptual studies on the equipment, facilities, and systems for drying treatments that dry unit cans and canisters individually orin groups will also be conducted. Furthermore, for the concepts of equipment, facilities, and systems for the drying treatment thathave been studied, the optimum operating conditions (range) from the viewpoint of conformity with safety requirements will be
studied and proposed. Based on these results, the qualitative evaluation of advantages and disadvantages will be made from theviewpoint of conformity with safety requirements, conformity with the required throughput, the required site area, construction
period, operations (frequency and duration of checks, inspection, and maintenance, the necessity and range of decontamination,
replacement frequency of parts, etc.), and so forth.

Details of implementation② Actualization of drying equipment concept
The concepts for drying equipment in the canister form were studied and the optimum operating
conditions were crystallized. In addition, drying treatment using the canister was compared with using
the chamber based on the results of test in 3.2① and then the advantages and disadvantages of theboth treatments were evaluated from the perspective of drying time, safety requirements, etc.
Essentially, multiple simultaneous drying can be applicable by increasing the number of drying lines at
the actual construction stage, while issues to be considered for applying the treatment wereconsolidated. Furthermore, requirements (requests) Note 1 for canister specifications were summarizedfrom the viewpoint of drying treatment.
[Results](1) Concepts of drying equipment in the canister form
(2) Optimum operating conditions for the canister form(3) Results of evaluation on advantages and disadvantages compared to the chamber method
Note 1: The marker section is from section 3.1 in©International Research Institute for Nuclear Decommissioning(4) Issues to examine for multiple simultaneous treatment
the solicitation information

3. Implementation items, their correlations, and relations withother research
Safety (overall)
Fuel debris transfer and storage system- Note 1:

No.10

Environment, physical properties, etc.

A

Study of the plan

Safety requirements

and storage of fuel debris
Setting and review of transfer
and storage methods, storage
areas Note 1

Review of criteria

Setting basic storage policies such as
wet storage and dry storage at new
facilities

Setting of fuel debris
quantities, storage area
candidates, etc.

Containing, transfer, andfor containing,transfer,
storageplan for fueldebris- Note 2:
Specific storage methods such as dry
vent storage and dry sealed storage
Related technological development:
Evaluation of the amount of hydrogengenerated, countermeasures forhydrogen generation

Physical properties andcharacteristics of fuel debris
MethodSetting of criteria forsafety requirements

Setting and review of transfer
and storage details Note 2

Setting of functional
requirements

Setting and review of transfer
and storage systemprocesses
Note 3Compatible with retrieval
requirements

No

Reflection into retrieval
methods and process
settings
Setting of requirements- Note 3:
Necessary processes for transfer andstorage such as drying, etc.
Related technological development:
Drying equipment, hydrogenmeasurement technology

Operational requirements
for fuel debris retrieval- Note 4:
Safety assessment
Related technological development:
Structural evaluation, evaluation of theNote 5amount of hydrogen generated

Yes- Note 5:
Go up for “Setting and review oftransfer and storage details”
Go down for “Review of overall safety
criteria”
If it is both the cases, go up and down

Safety (safety assessment of transfer andstorage systems)

Safety assessment and review at
the time of transfer and storage
Note 4Compliance with safety
evaluation standards
Yes
Proposed plan of containing,transfer, and storage for fueldebris

Note 5No
Note 6A- Note 6:
If the overall safety criteria aretentatively set and considered, they
may be reviewed as necessary toreflect the enhancement of knowledge
and progress of studies from researchand development©International Research Institute for Nuclear Decommissioning3. Implementation items, their correlations, and relations withother research

No.11

3.3 Relationship between Implementation items(Target schedule) B3④ Development of Technologies for Containing, Transfer, and Storage of Fuel Debris
Stage 2 (Period until the start of fuel debris
retrieval)

Item/FY

Period 3-①

2023
onwards

Maintain and manage safe plant conditions

Major events in the current
Mid-and-Long-Term
Roadmap

Start of fuel debris retrieval for the initial unit
Engineering for containing, transfer, and storage[Development of Technologies
for Containing, Transfer, andStorage of Fuel Debris]

0. Investigations into
containing, transfer, andstorage and research anddevelopment planning
1. Development of collecting
technology(Conducted in FY2020/21)

Planning
Update plan based on related projects, etc.
Canister
specification reviews
and structuralverification tests

2. Development of drying
technology
3. Investigation of cases ofhandling radioactive materials
in powder, slurry, or sludge form
(Conducted in FY2020/21)
Development of transfer
technology[Development of Technology
for Further Increasing theRetrieval Scale of Fuel Debris
and Reactor Internals] etc.

Development oftechnology for drying
treatment

Canister filter failure scenario selection andStudy of countermeasures against changes
to canister filter performance

consequence assessment

Expansion and enrichment of drying treatment methods andoperational parameters

Investigation of cases and analysis, organization,and comparison of knowledge and information
Clarification of issues in the dry storage offuel debris in powder, slurry, or sludge form
using current canisters

Hydrogen gas
generation tests andinvestigation oftransfer conditions

Verification, etc. of dry storage withcurrent canisters

Alignment with related technological developments

Field work (including engineering)
R&D

Team Meeting for Countermeasures for Decommissioning and Contaminated Water Treatment / Secretariat Meeting (86th meeting) Materials “FY2021
Decommissioning R&D Plan,” Added to “(Target schedule) B3④: Development of Technologies for Containing, Transfer, and Storage of Fuel Debris”©International Research Institute for Nuclear Decommissioning3. Implementation items, their correlations, and relations withother research
3.3 Relationship between Implementation items
International Research
Tokyo Electric Power Company Holdings, Inc.
Institute for Nuclear[Project Management for the Decommissioningof the Fukushima Daiichi Nuclear Power
Decommissioning (IRID)
Station]Canister (drying) project

Fuel debris characterization project[Provide information for the canister (drying)project]- List of fuel debris characteristics(Knowledge on their morphology, properties,
basic physical properties, etc.)
Waste project[Obtain information from the canister(drying) project]- Understanding storage conditions[Provide information to related projects](1) Study of equipment design and methods- Details of examinations of equipment
design and methods required from theviewpoint of the drying technology(2) Concepts for containing, transfer, andstorage equipment- Study of storage conditions

No.12

Project for further increasing retrieval[Provide information for the canister (drying)project]- Fuel debris collection and storage- Information related to criticality control(Constrained conditions, etc. formaintaining sub-criticality)[Obtain information from the canister (drying)project]- Collection method requests

Water treatment project

Canister (sludge) project[Provide information for the canister (drying)project]- Collected information and extracted issues
involving sludge drying, storage, etc.

[Provide information for the canister (drying)project]- Information on sludge to be dried generated
in water treatment system- Drying characteristics of sodium silicate
neutron absorber[Obtain information from the canister (drying)project]- Drying goals, operating conditions, etc.

Note) These abbreviations are also used in the following slides.
Project for further increasing retrieval: “Development of Technology for Further Increasing the Retrieval Scale of Fuel Debris and Reactor Internals” project
Fuel debris characterization project: “Development of Analysis and Estimation Technology for Fuel Debris Characterization” project
Waste project: “R&D for Treatment and Disposal of Solid Radioactive Waste” project
Water treatment project: “Development of Safety Systems (Liquid/Gas Systems, Criticality Control Technology)” project
Canister (sludge) project: “Development of Technologies for Containing, Transfer, and Storage of Fuel Debris (Treatment for Fuel Debris in Powder, Slurry,or Sludge Form)” project
Canister (drying) project: “Development of Technologies for Containing, Transfer, and Storage of Fuel Debris (Drying Technology for Fuel Debris)” project

Consistent results can be obtained by sharing and coordinating informationfrom related projects within IRID and the information provided by this project.
©International Research Institute for Nuclear Decommissioning4. Implementation schedule

No.13

FY2021

FY2022

1. Drying treatment methods such as types of objects
to be dried and drying form, and the expansion ofoperational parameters(1) Types of materials to be dried and expansionof data① Study of test plan
② Data expansion of element tests(2) Study of drying method applicability① Drying method applicability
2. Concepts of drying equipment and the
expansion of data required for setting operating
conditions(1) Expansion of data for the canister form
① Study of test plan② Design and manufacture of a canister for testing
Design and modification of full-scale test equipment③ Expansion of data via full-scale test(2) Actualization of concepts for drying
equipment① Actualization of concepts for equipment
3. Progress report, etc.

* Decision on
the grant(5/14)
Planned schedule

Actual schedule©International Research Institute for Nuclear Decommissioning5. Project organization
Tokyo Electric Power Company Holdings, Inc.
〇 Project Management for the Decommissioningof the Fukushima Daiichi Nuclear Power Station(As of the end of March 2022)

International Research Institute for Nuclear
Decommissioning (IRID) (Head Office)〇 Formulation of overall planning and technology management〇 Technology management such as the progress oftechnological developments, etc.

No.14
Related development
projects
Development of Analysis and Estimation
Technology for Fuel Debris
Characterization

Mitsubishi Heavy Industries, Ltd.

Toshiba Energy Systems &Solutions Corporation

Hitachi-GE Nuclear Energy, Ltd.

Development of Fuel Debris
Retrieval Method(1) Drying treatment methods such as
types of objects to be dried anddrying form, and the expansion ofoperational parameters(2) Concepts of drying equipment andthe expansion of data required forsetting operating conditions(1) Drying treatment methods such as
types of objects to be dried anddrying form, and the expansion ofoperational parameters (review)(2) Concepts of drying equipment andthe expansion of data required forsetting operating conditions(review)(1) Drying treatment methods such as
types of objects to be dried anddrying form, and the expansion ofoperational parameters (review)(2) Concepts of drying equipment andthe expansion of data required forsetting operating conditions(review)

R&D for Treatment and Disposal of Solid
Radioactive Waste

MHI-NS- Canister design
Sol tec- Element testing (acquisition of test data)

Development of Technologies for
Containing, Transfer, and Storage of Fuel
Debris (Treatment for Fuel Debris in
Powder, Slurry, or Sludge Form)

Note)
MHI-NS: MHI NS Engineering Co., Ltd.
Sol tec: MHI Solution Technologies Co., Ltd.
MHI-MS: Mitsubishi Heavy Industries Machinery Systems, Ltd.
RSG: Ryoyu System Engineering Co., Ltd.

MHI-MS- Study of modifications to full-scale drying equipment- Design and manufacturing of modified full-scale
drying equipment

RSG- Canister flow analysis
Chugai Technos Corporation- Element testing / full-scale drying tests(acquisition of test data)©International Research Institute for Nuclear Decommissioning6. Implementation details

No.15

6.1 Drying treatment methods such as types of objects to be dried anddrying form, and the expansion of operational parameters
6.2 Concepts of drying equipment and the expansion of data required forsetting operating conditions
Within the implementation details in this report, “Drying treatment methods
such as types of objects to be dried and drying form, and the expansion ofoperational parameters” is called “element tests” and the results of such test
were organized.

Within the implementation details in this report, “Concepts of drying equipment
and the expansion of data required for setting operating conditions” is called a“full-scale test” and the results of such test were organized.

©International Research Institute for Nuclear Decommissioning6.1 Element tests

Note 1: Φ45 mm × 100 mmH scale
Note 2: 3.7 wt% in terms of fuel debris, target is 0.1 wt%
Note 3: Slurry and sludge were conducted at full-scale (the reason will be
provided later)① Purposes and goals
FY2019/20 Implementation of element tests (beaker scale tests Note 1)

ZrO2 slurry was dried to 3.3 wt%Note 2 in 24 hours(requires a lot of time for drying)Target: Clarify the applicable range of thedrying treatment Deployment toSlurry and sludge
other types→ Drying rate

Obtained data on drying characteristics forporous media (zeolite), SUS beads, silica
sand, and ZrO2 slurry

No.16

Slurry and sludge
Concrete

Concrete
Impact assessments
by analysis(Test objective) Verify the applicability of drying treatment tomaterial types containing difficult-to-dry substances and hydrates(Results)① Specify the types of materials that can undergo the drying
treatment② Alternative countermeasure proposal for hydrogen generation→ Temperature

Element
tests Note 3→ Moisture content
rate
Image of the data obtained ① Drying
characteristic curve

Drying surface
Intermediate bed
Center→ Drying time
Image of the data obtained ② Internal
temperature distribution©International Research Institute for Nuclear Decommissioning6.1 Element tests② Comparison with existing technology

No.17

Under the project the Development of Technologies for Containing, Transfer, andStorage of Fuel Debris until FY2020, technology for safely handling and storing
lump-like or particulate fuel debris using the canisters was developed.
Additionally, conceptual studies of drying methods for difficult-to-dry-materials,
zeolite, and drying equipment of the unit cans were conducted.

On the other hand, both fuel debris in powder, sludge, or slurry form as well as
concrete are expected to be collected when retrieving fuel debris, so drying data
must be obtained to study the possibility of such material drying in the samemanner as fuel lump-like and particulate fuel debris.

©International Research Institute for Nuclear Decommissioning6.1 Element tests③ Implementation items and results

No.18

Note 1: Condition 1 was obtained as of FY2020. Data is expected to be
expanded based on input from the FY2021-2022 water treatment project(1) Study of test plan: Objects to be dried (1/2)• • • range of FY2021-2022 data expansion

Status of data acquisition for each material to be dried
Classification

Process

Outlines

Photo image

Data acquisition status (up to FY2020)
Zeol.

SUS

SlurryConc.

Unmeted fuelassembly

Pieces of broken fuel assemblies left
unmelted

Obtained―――

Lump-like fueldebris and MCCI

Molten materials slowly cooled down
into lump form

Obtained――

Not
obtained

Molten reactor core materials quickly
cooled down into small pieces

Obtained Obtained――

Structures withadhered fueldebris

Pieces of broken structures left
unmelted with fuel debris adhering tothem

Obtained Obtained――

Slurry and sludge

Fuel debris in powder and fineparticle form――

Filters with fuel debris in powder andfine particle form adhering to them

―

―

Not
obtained

Not
obtained

Filters with dry fuel debris powder
adhering to them

―

―

Not
obtained―

Pebble-like fueldebrisWater treatment
filter

Gas treatment
filterRetrievalprocess

Water
treatment
systemGas
treatment
system1 Condition
Not(ZrO2) Note 1 obtained©International Research Institute for Nuclear Decommissioning① Materials for which drying characteristics data has
not yet been obtained
a. Slurry and sludge containing treated and collectedfuel debris mixed with concrete powder andfragments of core structure material→ Flocculated and sedimented slurry and sludge withadded flocculant, to reflect the study in the water
treatment projectb. Fuel debris mixed with concrete pieces, fuel debris
adhering to concrete pieces
c. Water treatment filters and gas treatment filters withfine powder fuel debris adhering to them
② Assumed state before drying treatment
a. A decanter, cyclone, or similar equipment is used toseparate out some of the solid content before
containing material in a canisterb. Concrete pieces (glass form) contained in a canisterc. Sintered metal filter media and HEPA filter media
contained in canister

form

Study of assumed drying treatment conditions for materials tobe dried with data as yet not obtained

Types

a. Slurry and sludge

Canister(1) Study of test plan: Objects to be dried (2/2)

Conceptual
drawing

Canisterb. Concrete pieces

Canister③ Implementation items and results

Assumed state before drying No.19
treatment (example)

Canisterc. Filter media

Canister

6.1 Element tests

Canister©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.20③ Implementation items and results(2) Study of test plan: Test policy
Hot air(Test objective) The test aims to verify the applicability ofdrying treatment to material types containing difficult-to-dry
substances and hydrates(Results)① The types of materials that can undergo the drying
treatment were specified.
② Alternative countermeasure proposal for hydrogengeneration[Test policy]i.
The range of application for the current treatment
concept with difficult-to-dry materials (moisture content
rate at 24 hours (reference)) shall be verified.
ii.
The necessary alternative countermeasures forhydrogen generation and their methods shall be
proposed based on trends in acquired data.

Canister
Exhaust(Suction from slightnegative pressure)

External heatup

UC Note1

Current treatment concept(FY2019-2020 examination results
when drying in a canister Note 2)

Note 1: “UC” represents unit can.
Note 2: Replace canister with drying chamber when drying in a drying chamber.
©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.21③ Implementation items and results(3) Study of test plan: Test items and objectives (1/3)••

The assumed drying conditions is applied to the current treatment concept and tests shall beplanned.
A method of the “Proposal ③ the inner container filled with slurry and sludge” was applied to thedrying treatment method for canisters filled with slurry and sludge.
Atmosphere gas

Hot air

Hot air
Exhaust (Suction fromnegative pressure)Exhaust (Suction fromnegative pressure)Exhaust (Suction
from slightnegative pressure)
External heatup

Canister

Clogged with sludge[Proposal ① Direct filling]
1. Assuming that current canister
specifications using air supply
and exhaust vents are applied.
However, an internal filter isadded to prevent the spread ofcontamination
2. There is a high possibility thatairflow treatment cannot be
conducted due to clogged the air
supply vent with sludge.

⇒ X (Not applicable)

Hot air

Exhaust (Suction
from slightnegative pressure)
External heatup

External heatup

Conducting
tube

CanisterSludge[Proposal ② Add conducting tubes]
1. Add conducting tubes andnozzles

Canister[Proposal ③ Fill an inner container
with slurry and sludge]
1. The container is doubled-walled
and the inner container is filledwith sludge

2. Drying treatment can beavailable, but the canister will bevery expensive. This proposal isunrealistic.

2. The risk of clogging pipes will besignificantly reduced.

⇒ X (Not applicable)⇒ 〇 (Applicable)©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.22③ Implementation items and results(3) Study of test plan: Test items and objectives (2/3)

Externalmesh unit can

HeaterDry zone
Wet zone
Cutaway

Issues in element tests with an inner container filled with slurry andsludge• The equipment in the FY2019-2020 beaker scale test assumed thatboth heat transfer and moisture transfer moved in the same direction.
(Figure 1)

Based on the above points, a full-scale test should be conducted to test
an inner container filled with slurry and sludge.

Moisturetransfer(Drying)DryingFigure 1: Beaker scale test
Hot air

When using an inner container filled with sludge and slurry, however,heat is transferred from the side and moisture moves threedimensionally, evaporating from the open top. (Figure 2)<Issues from the difference in direction between heat transfer andmoisture transfer>✓ The directions of movement for heat transfer and moisturetransfer do not match. Therefore, the equipment from the FY20192020 beaker scale drying test cannot be used.
✓ Evaluation of actual scaled-up equipment after obtaining reducedscale test data is difficult with three-dimensional drying behavior.
✓ In scaled-down models, heat capacity (volume) is relatively
smaller than heat input (external surface area) and so thetemperature of the test piece (thus its drying rate level) is higher
than it would be in an actual equipment under the same heating
conditions. (Figure 3)

Heattransfer

Heat
transfer

External
heatupHeattransfer

Moisturetransfer

Figure 2: Slurry and sludge drying
Temperature [°C]•

Hot air

Scaled-downsystemFull-scale system

0 (Center)

1 (Exterior)

Dimensionless radical distance [-]Figure 3: Schematic diagram of temperature
distribution in scaled-down and full-scale systems©International Research Institute for Nuclear Decommissioning6.1 Element tests

Note 1: See the figure on slide No. 20.
Note 2: The time from the heater turning ON
and the start of airflow
Note 3: Wet/dry weight. Target: 0.1 wt% interms of fuel debris③ Implementation items and results

No.23(3) Study of test plan: Test items and objectives (3/3)
Data will be obtained as listed below to clarify the range of application for the existing concept.
Material tobe dried

Assumed application oftreatment concept Note1

Test typeHot air
Exhaust(Suction fromslight negative
pressure)

Slurry andsludgeFull-scale

External
heatupFull-scale
Canister

Hot air

Concrete

Exhaust(Suction fromslight negative
pressure)
BeakerExternal
scale
heatupCanister
Assuming acceptanceof the UC

Filter media

Packed directly in acanister

Analysis

Items

Objective and outline

Data andinformation to beobtained

Using the currently
DryingInternal
assumedslurryandcharacteristi
temperature/time Notesludge,obtaindata
on
2 vs Moisture content
cs oftemperature drying characteristics with rate Note 3
temperature and fillingvolume as parameters,
Dryingand verify the range toFilling volume/time
characteristi which the existing
Note2 vs Moisturecs of filling treatment concept can becontent rate Note3
volumeappliedStudy changes inmoisture content rate overDryingtime and verify the drying Time Note2 vscharacteristi
time of external seepage Moisture content ratecs ofwater to evaluate theNote 3
concrete
impact of hydrates inside
the concreteUse test data on slurry
Range ofand sludge, etc. to verify
dry material whether filter media can Analysis results
types
be dried and the types of
media that canbe dried©International
Research Institute for Nuclear Decommissioning6.1 Element tests

No.24③ Implementation items and results(4) Data expansion of element tests 1 (full-scale slurry and sludge test plan (1/2))〇 Test objective• Use full-scale test equipment to verify whether the target moisture content rate via drying can be achieved (achievable
treatment time) for slurry and sludge discharged from sedimentation equipment.
• Verify the impacts of drying temperature (heater surface temperature) and filling height in case it is not achievable or asa proposal for reducing drying time.
〇 Evaluation method• Measure temperature distribution within the sample, the mass of the sample, and changes in the dew point of exhaustgas over time, and evaluate the degree of moisture content rate attained and the drying rate (moisture reduction rate).
• Collect particles in the exhaust gas.
〇 Treatment conditions• Drying method: side heater + hot air heatup〇 Slurry and sludge conditions• Heater surface/hot air temperature: 200°C, 300°C• Slurry and sludge: Silica sand Note 1, 2 (1 condition) • Filling height: 200 mm minimum (observe dispersion• Flocculant : Aluminum sulfate Note 1 (1 condition)
conditions and adjust test conditions to verify the impact of• Slurry and sludge particle size: 10 to 100 µm
fill height)

Table: Proposed test conditions
Slurry and sludge
material

Particle size[μm]Filling height[mmH]

Silica sandAl2(SO4)3
Silica sand + Al2(SO4)3
Representative
condition 1 Note 3

10 to 100――

200/400
200/400
400

Heatersurface/hot air
temperature [°C]
200
200
200

―

200

300

up to 10up to 10up to 10

Flow velocity Note 4[m/s](Flow rate [Nm3/h])
3(37)
3(37)
3(37)

up to 103(37)Heater output[kW]

Note 1: Only material discharged from the roughing system in the water treatment project is targeted and representative condition 1 is selected for slurry, sludge, and the flocculant
Note 2: Silica sand was selected from the components of simulated slurry and sludge (tungsten carbide, SUS316L, silica sand) in the water treatment project element tests as it has the highest
moisture content rate and is considered to be difficult to dry
Note 3: Determined based on other test results Note 4: The chamber annulus section© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

24©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.25③ Implementation items and results(4) Data expansion of element tests 1 (full-scale slurry and sludge test plan (2/2))•

Data on the drying characteristics of the slurry and sludge in the
inner container shall be obtained.
F(Test conditions and system)• Hot air drying• The inner container is filled with slurry andsludge, which is then dried in the drying
chamber• Material to be dried: Flocculated andsedimented slurry and sludge(Examined in the water treatment project)• Measure the internal temperature of theslurry and sludge / Measure the weight of
retrieved material (obtain data on drying
characteristics)(Test parameters)• Sample material, temperature, slurry andsludge filling height

M

T

Chiller

BlowerFilterCondenser

F
P

Flow line invacuumoperation

Vacuumpump

W

T
External
heaterRetrieval of innercontainer for slurry
and sludgeW

T (Measurement of temperature
distribution)
Drying chamberW: Weight scale

T: ThermometerP: Pressure indicatorM: Dew-point meter
Condenser

F: Flowmeter

Dehumidifier

Air

Dryer

HeaterInner container for slurry andsludge ϕ 210 × H 1000 (MAX)F

HeaterT

M

Vacuumpump

Simplified
schematicof the full-scale
test system
Figure:Schematicof the full-scale
drying test system
External
appearanceof the Institutefull-scale
system©International
Research
fordrying
Nucleartest
Decommissioning6.1 Element tests

No.26③ Implementation items and results(4) Data expansion of element tests 1 (full-scale slurry and sludge test results (1/2)• • • Silica sand 200 mm (20% height)

CenterTemperature [°C]

800 mmTemperature [°C]

Exterior

Temperature
measurementpoint

600 mmCenterMid-level

Exterior

400 mm
300 mm
200 mmDrying time [H]

100 mmTemperature change at 200 mm (20% filling height) Left: Center (0 to 800 mm) / Right: Radical direction (100 mm)

10 mm
0 mm (center only)State at beaker scale construction(However, the supernatant wasremoved before drying)

Weight measurement results
Absolute dry weight Note 110280g

Initial moisture content
rate Note 2

36%

Amount of residual
moisture after 12 hours≒ 0 Note3

Moisture content rate
after 12 hours Note2≒ 0 Note3

Moisture content rate[%]

Mid-level

Drying time [H]Change inmoisture content
rate

Drying time [H]Note 1: Weight when heated at 300°C for 5 hours Note 2: Moisture content rate/Absolute dry weight (weight after holding at 300°C©International
Research Institutefor Nuclear Decommissioning
for minimum 5 hours). Drying target is 0.2 wt% (target moisture content rate in terms of fuel debris)
Note 3: Including
measurement
error Error evaluation is in progress6.1 Element tests

No.27③ Implementation items and results(4) Data expansion of element tests 1 (full-scale slurry and sludge test results (2/2)• • • Flocculant (Floc) 200 mm (20% height)

Center

600 mm

0 mm
100 mm
300mm
600 mm

400 mm

10 mm
200 mm
400 mm
800 mmTemperature [°C]

800 mmTemperature [°C]

Exterior

Temperature
measurement
point

CenterMidlevel

Exterior

300 mm
200 mm
100 mmDrying time [H]Temperature change at 200 mm (20% filling height) Left: Center (0 to 800 mm) / Right: Radical direction (10 mm)

10 mm
0 mm (center only)State at beaker scaleconstruction

Weight measurement results
Absolute dry weight Note 1363g

Initial moisture content
rate Note 2

1927%

Amount of residual
moisture after 18 hours

7g

Moisture content rate
after 18 hours Note 2

1.9% Note 2

Moisturecontent rate[%]

Mid-level

Drying time [H]Note 1: Theoretical value calculated from the amount of input reagent for the mass of material generated when heated to 200°C
Note 2: Moisture content rate/Absolute dry weight. Target is 0.2 wt% (target moisture content rate in terms of fuel debris) However,absolute dry weight is currently being evaluatedChange inmoisture content
rate

Drying time [H]©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.28③ Implementation items and results(4) Data expansion of element tests 2 (concrete beaker scale test: overall plan)➢ A beaker scale drying test shall be conducted to understand the effects of hydrates withinconcrete on drying characteristics.
➢ Concrete contains cement components (such as calcium), aggregates (such as silica), andadditives (surfactants).
➢ Therefore, concrete composition parameter tests shall be conducted to verify the extent ofinfluence on the drying behavior of concrete composition.
➢ In addition, the effects of concrete piece size and treatment conditions (gas temperatureand gas flow velocity) shall be verified to reflect findings in actual equipment design andtreatment conditions.
〇 Concrete conditions〇 Test parameters:• Cement: Ordinary Portland cement (JIS R• Concrete composition Note 1
5210)- Water/cement weight ratio• Fine aggregate: Sand (fineness modulus: 2.5- Aggregate/cement weight ratio
to 2.9)- Fine aggregate/coarse aggregate weight• Coarse aggregate: Gravel (fineness modulus:
ratio
6.2 to 6.6)
• Diameter of concrete particle• Chemical admixture: Water reducing agent,• Gas temperatureetc. (selected in accordance with JIS A 6204)• Gas flow rate
+

+

+

+

+

+

+

+

Fineness modulus = 𝑋40 𝑋20 𝑋10 𝑋5 𝑋2.5 𝑋1.2 𝑋0.6 𝑋0.3 𝑋0.15
100
Xi: Ratio of aggregate mass retained in the imm sieve [%]Note 1: Also plan to obtain the thermophysical properties in
addition to the beaker scale test
©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.29③ Implementation items and results(4) Data expansion of element tests 2 (concrete beaker scale test: physical properties measurement test plan)〇 Measurements of the physical properties of concrete material• The physical properties that contribute to the drying behavior shall be measured in order to evaluate thedrying behavior of concrete materials.
• The following items will be measured.
✓ Thermophysical properties (thermal conductivity and specific heat): Evaluate the correlation between concrete composition and impacts on drying behavior.
Note
1✓ TG/DTA-MS: Verify the thermal decomposition behavior during drying treatment.
✓ Pore diameter distribution: Compare moisture adsorption characteristics with zeolites.
• The following table lists the measurement conditions for each physical property.
Run

Water/cement Aggregate/ratio
cement ratio

Fine
AE agent Note2/cement
aggregate/total
Blending parameter
aggregate ratio
ratio
evaluation items
[wt%]
[wt%]

ThermalSpecific heat
conductivity

TG/DTA-MS

Pore diameter
distribution

[wt%]

[-]

1

55

5.4

44

0.03

Base condition

Conducted

Conducted

Conducted

Conducted

2

45

5.4

44

0.03

Conducted

Conducted

Conducted

Conducted

3

70

5.4

44

0.03

① Water/cement weight
ratio

Conducted

Conducted

Conducted

Conducted

4

55

3.0

44

0.03

Conducted

Conducted

―

―

5

55

6.0

44

0.03

② Cement/total
aggregate weight ratio

Conducted

Conducted

―

―

6

55

5.4

60

0.03

Conducted

Conducted

―

―

7

55

5.4

30

0.03

③ Fine aggregate/total
aggregate weight ratio

Conducted

Conducted

―

―

A

55

0

―

―

Conducted

Conducted

Conducted

Conducted

B

40

0

―

―

Conducted

Conducted

Conducted

Conducted

C

70

0

―

―

Conducted

Conducted

Conducted

Conducted

Presence of aggregate
in Run 1
Presence of aggregate
in Run 2 Note 3
Presence of aggregate
in Run 3

Note 1: Simultaneous measurement of thermogravimetric/differential thermal analysis and gas mass spectrometry Note 2: Air Entraining Agent
Research Institute for Nuclear Decommissioning
Note 3: The water/cement ratio is slightly lower in Run 2 because water was added to address poor clumping during blending in©International
Run 2.

6.1 Element tests

No.30③ Implementation items and results(4) Data expansion of element tests 2 (concrete beaker scale test: physical properties measurement test results(1/3))〇 Results of thermophysical property measurements (thermal conductivity and specific heat)• Both thermal conductivity and specific heat were greatly affected by the aggregate/cement ratio (with orwithout aggregate), while other compositions showed relatively small impact.
• The higher aggregate/cement ratio, the lower the overall cement ratio and therefore the lower ratio offine voids, etc., present in the cemented portion, which may have resulted in a tendency toward highthermal conductivity.
• Since the specific heat of aggregate is less than half that of cement, the significant differences in
specific heat may have been the result of the presence or absence of aggregate.
Table: Specific heat measurement results
Thermal conductivity @ 200°C [W/mk]

Thermal conductivity @ 200°C [W/mk]

Run

Aggregate/cement ratio [-]Withaggregate
Without
aggregate

Water/cement ratio [wt%]Figure: Thermal conductivity measurement results

Specific heat [J/K·g]/
measured temperature [°C]
207

297

1

1.4

1.3

2

1.4

1.3

3

1.4

1.4

4

1.4

1.3

5

1.3

1.2

6

1.4

1.3

7

1.4

1.3

A

2.8

2.2

B

2.7

2.2

C

2.9

2.3

Fine aggregate

1.1

1.2

Coarseaggregate

1.2

1.2

©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.31③ Implementation items and results

CO2
1st time

content rate [wt%] rate attained [wt%]
4.2
0.3
6.8

0.3

3

3.3

0.3

A

16.8

1.3

B

17.8

1.2

C

18.3

1.2

* Run 1 to 3 are average values of N number 3* Moisture content rate = Volume of water/Absolute dry weight × 100
Calculated based on the initial value at the start of temperature rise,
the end point of drying after holding at 200°C for 5.5 hours, andthe absolute dry weight after holding at 300°C for 1 hour

3rd time
TEMP [°C]

No CO 2 generation notconfirmed while holding at
200°C

Temperature (°C)

2

2nd time

Intensity (A)1

1st time

Figure: TG/DTA measurement results

Table: Moisture content rate evaluation
results Moisture content
Initial moisture

Run

While holding at 200°C,
endothermic reaction notconfirmed.

Heat flux [µV]

〇 TG/DTA-MS measurement results• Samples without aggregate tended to have a high initialmoisture content rate due to the large amount of
cement, which absorbs moisture easily.
• Remarkable heat absorption and weight reductions wereobserved when the temperature was raised to 200°C,
but very little was observed when held at 200°C.
• Therefore, although moisture desorption and thermal
decomposition due to temperature rise is possible, it isbelieved to have little effect during drying treatment at
200°C.

Rate of decrease in weight[wt%](4) Data expansion of element tests 2 (concrete beaker scale test: physical properties measurement test results(2/3))

Measurement time (min)Figure: MS measurement results of generated gas©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.32③ Implementation items and results(4) Data expansion of element tests 2 (concrete beaker scale test: physical properties measurement test results(3/3))〇 Pore diameter distribution measurement results• It was verified that average pore diameter was almost the same regardlessof the water/cement ratio and the presence or absence of aggregate.
• It was verified that samples without aggregate tended to have large porevolume and large specific surface area.
• Compared to zeolite, average pore diameter in the 0 to 4 nm range withinconcrete samples was verified to be slightly less than twice as large, andpore volume was also verified to be one order of magnitude smaller.
• Therefore, the effect on drying from water adsorption is believed to be lesswith concrete material than with zeolite.

Run A

Table: Results of measurements in pore diameter and pore volume
Measurement range
Run

0 to 4 nm
AveragePore
pore
volumediameter[nm][cm3/g]1 to 200 nm
AveragePore
pore
volumediameter[nm][cm3/g]Specificsurfacearea

Zeolite[m2/g]

1

1.66

0.006

11.00

0.031

10.99

2

1.70

0.014

6.60

0.041

23.58

3

1.69

0.022

7.18

0.074

38.00

A

1.72

0.039

7.77

0.140

66.23

B

1.72

0.029

7.61

0.101

49.59

C

1.73

0.038

10.43

0.190

65.39

Zeolite

0.95

0.135

9.57

0.141

341.24

Figure:Pore diameter
distribution
measurement©International
Research Institutefor Nuclear
Decommissioning
results

6.1 Element tests

No.33③ Implementation items and results(4) Data expansion of element tests 2 (concrete beaker scale results: drying test plan (1/2))➢ The beaker scale test equipment manufactured in FY2020 will be used to conduct a drying test
on concrete pieces to understand the correlation between concrete composition and drying
characteristics.
Cold trap

Block heater

Vacuumregulator

VCR joint

ChillerAir

Moisture
absorption
tower

Plate heaterGas dryer

Gas heater

VCR joint

Sample temperature is measured at 3mm, 25 mm, 50 mm, and 75 mm fromthe surface of the sample(The height of test sample is 100 mm)

VCR joint

Sample temperature is measured at 3 mm,
25 mm, 50 mm, and 75 mm from thesurface of the sample (the height of test
sample is 100 mm)

FIC: Mass flow controller
TR: Thermometer (thermocouple)
TIRC: Heater control thermometer
EIR: Heater output indicator

Vacuum pump
TR: Thermometer(thermocouple)
TIRC: Heater control
thermometer
EIR: Heater output indicator
PIR: Pressure indicator

Figure: Simplified schematic of the decompression drying element test system

Figure: Simplified schematic of the hot air drying element test system

Test containerGas heaterCompressor

Gas flow

Moisture
absorption
tower

3D CAD drawing of a test
container for hot air drying
element test system

Gas dryer

Inner diameterΦ45 mmFigure: External appearance of the hot air drying element
test system

Figure: External appearance of a test container
filled with water containing piece samples

3D CAD drawing of a test
container for decompression
drying element test system©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.34③ Implementation items and results(4) Data expansion of element tests2 (concrete beaker scale results: drying test plan (2/2))〇 Test objective• The objective of the test is to acquire data on the drying characteristics to formulate drying treatment conditions forconcrete pieces.
• On the basis of the test data obtained, a quantitative evaluation of differences from zeolite and metal balls tested in
FY2020 shall be performed to discover the applicable drying treatment conditions for each material to be dried.
〇 Evaluation method• The evaluation shall be performed by measuring the temperature distribution of the sample and the change in mass ofthe sample over time to assess the moisture content rate attained and the drying rate (moisture reduction rate).

Table: List of test conditions
Coarseaggregate/fineaggregate Note 1

Diameter ofFilling
Gas
Gas flow
concreterate temperature
rate
particle[vol%]
[°C]
[m/s]
[mm]

Water/cement
Note 1Aggregate/
cement Note 1

[-]

[-]

1

55

6

1.3

10

Resultant

200

1

2

55

6

1.3

5

Resultant

200

1

3

55

6

1.3

20

Resultant

200

1

4

55

0

―

10

Resultant

200

1

5

55

6

1.3

10

Resultant

200

3

6

55

6

1.3

10

Resultant

200

0.1

7

55

6

1.3

10

Resultant

300

1

Run

[-]

Note 1: Concrete component conditions are set with reference to the 1F construction report (see Note 2) and thermophysical properties, etc., and added or changed as required.
Note 2: Nomura et al., “Construction report on the Fukushima Nuclear Power Station Unit 3,” Concrete Journal, vol.12, No.6, 1974
© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

34©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.35③ Implementation items and results(4) Data expansion of element tests2 (concrete beaker scale results: drying test results)

Temperature [°C]

Temperature (°C)

Moisture content rate (%)

〇 Comparative evaluation versus zeolite samples• Drying test was conducted on concrete samples under the same test conditions as the FY2020 zeolite
samples.
• Compared to zeolite, concrete test pieces were verified to require less time to reach a constant internal
sample temperature (completion of a constant drying rate).
• This is most likely because concrete samples have larger particle diameters and lower water absorption
properties compared to zeolite, resulting in less moisture adhesion to the material and lower initialmoisture content rate Note 1.
• The end point of drying will be evaluated in the future by measuring the mass at the point where drying
treatment time is 10 to 20 hours.

3 mm from sample surface

25 mm from sample surface
50 mm from sample surface
75 mm from sample surface

Elapsed time [h]Zeolite (FY2020 test)
Run 5 (formula weight Run
1, particle size 20 mm)

Elapsed time (h)Elapsed time (h)Figure: Change of moisture
content rate over time

Figure: Change of internal sample temperature over time
(Left: Concrete, Right: Zeolite (FY2020))
Note 1: Moisture content rate = Volume of water/Absolute dry weight ×100© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

Absolute dry weight is the weight when holding at 300°C for35
at least 5©International
hours
Research Institute for Nuclear Decommissioning6.1 Element tests

No.36③ Implementation items and results(5) Content of analysis
The following items were studied by using the analysis model.
•

Evaluation of concrete drying based on element tests, development to a full-scale system•

Sensitivity evaluation of drying time based on the type of material to be dried, such as filter
media©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.37③ Implementation items and results(6) Analysis model••

Considering that the movement of heat and water vapor is
predominantly perpendicular in heat transfer and drying, aone-dimensional model is considered.
Regarding the dry and wet zones, drying causes theboundary surface (called the drying surface) to moveinward. (One idea in the falling rate drying model)
Unit can(UC)

Drying rate𝑊=

Dry zone
Wet zone
Depth of the drying
surface δHeat transfer
Drying1
𝛿+ℎ𝐷 𝜀𝑑 𝐷𝑄=

Depth of the dry
surface δ

Gas
flow

Drying (diffusion of water vapor)p1

pΦ
Heat transfer
UC

𝑝𝜙
𝑝1
−
𝑅𝑤 𝑇𝜙 𝑅𝑤 𝑇1

𝐴Heat transfer rate

Material to be dried
Wet zone Dry zoneTΦ

Drying and heat transfer rates are calculated from theresistance and drive force between the atmosphere and thedrying surface (drying rate is the vapor pressure difference
and heat transfer rate is the temperature difference).

T1
Chamber

Schematic diagram of drying and heattransfer (longitudinal section)

𝐴

1
𝛿
+
ℎ 𝜀𝜆 𝜆𝑇1 − 𝑇𝜙

A: Area [m2]
D: Diffusion coefficient of water vapor [m2/s]
h: Heat transfer coefficient of the outer surface of thematerial to be dried(Radiation is considered separately) [W/(m2-K)]
hD: Mass transfer coefficient of the outer surface ofthe material to be dried [m/s]hfg: Latent heat [J/kg]
p1: Partial pressure of steam in the atmosphere [Pa]pΦ: Partial pressure of water vapor in the drying
surface [Pa](= saturated vapor pressure at TΦ)
Q: Amount of heat transfer [W]
Rw: Gas constant of water vapor [J/(kg-K)]
T1: Atmospheric temperature [K]TΦ: Temperature of the drying surface [K]W: Drying rate [kg/s]
εd, ελ: Compensation coefficient regarding porosity,
etc. [-]
δ: Depth of the dry zone [m]λ: Thermal conductivity of the material to be dried[W/(m-K)]

Calculate T Φ from the relationship between the drying rate andthe heat transfer rate in the following equation.

𝑊 = 𝑄 Τℎ𝑓𝑔

Drying rate W causes the depth of the drying surface δ toincrease with time (as drying progresses).
Adding W gives the average reduction in moisture content
rate.

The atmosphere, water vapor partial pressure on the drying
surface, and temperature are obtained from drying test
measurement data and the depth of the drying surface δ isestimated from the measured temperature. The thermal
conductivity of the sample is obtained separately. εd and ελ are
adjusted from these data and the changes in moisture content
rate in the test over time.
The difference in the type of material to be dried is reflected in λ,and the difference in shape is reflected in A and δ for evaluation.

©International Research Institute for Nuclear Decommissioning6.1 Element tests③ Implementation items and results

No.38(7) Summary• Data of objects to be dried, such as slurry, sludge, and concrete, and their storage forms which has
not yet been obtained was organized. (No.18 to 19)• Regarding objects to be dried which data has not yet been obtained, a method of applying drying
concepts developed n FY2019/2020 objects was examined. Element test plan was developed
depending on each storage form. (No.20 to 23)• Currently element tests have been conducted to verify the drying characteristics of slurry, sludge andconcrete, with their current status as follows. (No.24 to 35)① The slurry and sludge simulant silica sand and flocculant (filling height 200 mmH) completed
drying in 12 to 18 hours② Results of TG/DTA-MS (simultaneous measurement of thermogravimetric/differential thermal
analysis and gas mass spectrometry) show that temperature rises in concrete could potentiallylead to moisture desorption and the thermal decomposition of water crystals, but the effect isminimal during drying treatment at 200°C③ Compared to the zeolite tested in FY2020, concrete pores are one magnitude smaller in porevolume and the effect of moisture adsorption on drying is small.
• Concrete drying evaluation is being planned based on analysis element tests and the sensitivity
evaluation on drying time is also planned depending on the type of material to be dried, such as filter
media expansion and applying to a full-scale system. (No.36 to 37)©International Research Institute for Nuclear Decommissioning6.1 Element tests

No.39➃ Contribution of outcomes to relevant study areas• The expanded data on the materials to be dried will be organized to contribute to thecountermeasures for hydrogen generation during transfer in future.

⑤ Analysis with respect to the on-site applicability• Equipment specifications will be examined from the perspective of on-site operations,such as presenting optimum operating conditions.

⑥ Issues• There are no issues in executing the current plan.

⑦ Goal achievement level• Tests are currently ongoing and are expected to produce the desired results
according to plan.

⑧ Future plans• Element tests will be continued to verify the drying characteristics of slurry, sludge,
and concrete.
• In FY2022, the continuation of element tests and the sensitivity evaluation of drying
time via analysis will be conducted, and the applicability of the drying concept foreach material to be dried will be evaluated.
©International Research Institute for Nuclear Decommissioning6.2 Full-scale test
① Purposes and goals
FY2019-2020
Conducted full-scale drying chamber test

No.40

Note 1: 0.1 wt% in terms of fuel debris (target moisture content rate is 0.1 wt% in terms of fuel debrResults from FY2019-2020 evaluations(chamber method)

Dried porous media for 16 hours to amoisture content rate of 0.3 wt%Note 1

Exhaust or decompression
Install an empty cylinder toreduce powder dispersion(linear velocity)

Target: Rationalize the treatment

Canister method(Test objective) The test objective isto verify the feasibility of drying
treatment using the canister method(Results)① Prevention of spreading
contamination from the drying
treatment② Simplified the treatment
procedures (reduce UC loading
and unloading procedures)Install diffusion pipes
to apply air evenly tothe interior

Hot air→ Moisture content
rateSpace above each UC

Full-scale test

→ Drying time

Conceptual image of data obtained
Drying time and moisture content rate
©International Research Institute for Nuclear Decommissioning6.2 Full-scale test
② Comparison with existing technology

No.41

Under the project the Development of Technologies for Containing, Transfer, andStorage of Fuel Debris until FY2020, technology for safely handling and storing
lump-like or particulate fuel debris using the canisters was developed.
Additionally, conceptual studies of drying methods for difficult-to-dry-materials,
zeolite, and drying equipment of the unit cans were conducted.

On the other hand, compared to the chamber form drying method studied in
FY2020, the applicability of the canister form drying method (which isconsidered effective in suppressing the spread of contamination) has not yet
been verified. Therefore, it is necessary to obtain drying data on the canister
form and compare its advantages and disadvantages with the results of thechamber test, and then to organize the requirements for the canister structure
proposal from the viewpoint of drying treatment for fuel debris in slurry andsludge form, concrete pieces with fuel debris attached, filter media, etc.

©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.42

③ Implementation items and results(1) Study of test plan: Test objectives〇 Test objective• The test objective is to verify the feasibility of achieving (achievable treatment time) the drying target moisture content
rate (0.1 wt% in terms of fuel debris) in order to examine the feasibility of drying treatment using a full-scale canister
method.
• The requests for the current canister structure proposal shall be organized with respect to drying in case it is notachievable or as a proposal for reducing drying time.
〇 Evaluation method• Data on drying time and moisture content rate shall be obtained by changing the nozzle and flow rate conditions.

Chamber method(FY2019-2020)
Target moisture content
rate attained in 16 hours

Install an empty cylinder toreduce powder dispersion(linear velocity)

Space above
each UC

Installation of diffusion pipes toapply air evenly to the interior

Current canister design proposal• Diffusion is located on the side of the entrance andexit• No space between UCs for maximum storage capacity• A filter is installed inside to suppress powderdispersion
The possibility of drying and issues will be verified underthese conditions.

The effect of improving the uniformityof the internal flow will be verified.
(improvements to nozzle diameter,
number, and position)

Requests to thecanister with respect
to drying©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.43

③ Implementation items and results(2) Study of test plan: Test equipment (1/2)
Chamber method full-scale test equipment (FY2019-2020) →Modified in the canister method
M

Note 1F
ChillerT

BlowerCondenser

P

Vacuum pump

Flow line invacuum operation
W

RemovalUC aftertreatmentW: Weight scale

T: ThermometerP: Pressure indicatorM: Dew-point meterF: Flowmeter

W

External
heater[Unit can]Dimensions: ø 210 ×
200 in mm
Stacking number: amaximum of 4

(Test conditions and system)• Hot air / periodic drying• Connect the test equipment system to thecanister nozzle• A maximum of 4 unit cans (UC) inside thecanister• Drying target: Zeolite• Measure weight after drying and obtaindata on changes over time for the amountof condensation, dew point, gas flow rate,
temperature, etc. Note 1(Test parameters)• Canister nozzle dimensions, number ofnozzles, hot air flow rate
Note 1: Plan to change the installation position of the dew point
meter from the FY2019-2020 equipment and verify
improvements to the method for determining drying
completion
HeaterCondenser
Dryer

Modified in thecanister method
Dehumidifier

F

T

M

Air

HeaterVacuumpump

Figure: Schematic of the full-scale drying test system
Figure:ExternalResearchappearanceof Nuclear
the full-scale©International
Institute for
Decommissioning
drying test system

6.2 Full-scale test

No.44

③ Implementation items and results(2) Study of test plan: Test equipment (2/2)
Illustration of drying in a canister- Variable outlet nozzle diameter andnumber (connector)- Flow rate change

Existing test
equipment

Existing test
equipment- Variable inlet nozzle diameter andnumber (connector)

Drying target: Zeolite- Filling height 100 vol%- Initial moisture content rate
approximately 40 to 45 wt%(Equivalent to the FY2019-2020
chamber test)© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

Canister heater
44©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.45

③ Implementation items and results(3) Study of test plan: Modification issues and test content

Pressure loss

Issues based on the shape of the canister in the
Canister nozzle surface area - Pressure
current planloss (Image)• The diameter of the canister piping is smaller
than that in the existing full-scale test
Unachievableequipment using the chamber method andthere are fewer pipes, which results inexcessive pressure loss.
Larger• Since fuel debris drying equipment is assumed
flow rate
to control negative pressure, there is a limit to
the pressure system that can be created.
MediumDecompression• The condenser and dew point meter cannot
flow rate(-100 kPa)
function or conduct measurements because
they fall outside the operating pressure range
Low flow rateof the test equipment components andinstruments.
Current canister design Canister nozzle surface area

[Test details]
There will be two tests with different items to be measured depending on
test objective.
✓ Canister dryability test
Compare the drying time in the current canister design with the data fromthe chamber method without using a condenser or dew point meter✓ Acquisition of data on drying time using canister design conditions asparameters
Drying trends (amount of condensation, dew point temperature) shall bemeasured when changing canister nozzle design and flow rate, and theresult will be used as canister design data.
© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

Inlet pipe Φ65 × 1 (65 A)
Outlet pipe Φ40 × 4 (40 A)
Rated gas flow velocity
Note 1 3 m/s
Note 1: Chamber UC annulus
section

Inlet pipe innerdiameter Φ7.5 × 1
Outlet pipe innerdiameter Φ7.5 ×1

Chamber(Existing test equipment)

Canister

Maximum gas flow velocity
0.1 m/s (when using a condenser anddew point meter)
1 m/s (when not using a condenser
and dew point meter)
45©International Research Institute for Nuclear Decommissioning6.2 Full-scale test
③ Implementation items and results

No.46
Note 1: Time from heater ON and the start of airflow
Note 2: Moisture/dry weight. Target: 0.1 wt% in terms of fuel debris(4) Study of test plan: Test content and objectives
Category
I. Verificationof canister
dryability

II. Acquisitionof data onchanges indrying time

Items

Data and information to
be obtained

Outlines

RUN⓪ Comparison with thechamber method

Collect RUN① comparison data (assume the same
flow rate and gas temperature at the canister inlet)

RUN① Drying with thecurrent canister design

Drying operations with the current canister plan shallbe conducted to verify the possibility of drying
treatment.

RUN② Increase nozzle
diameterNozzle diameter shall be increased and drying
treatment shall be conducted using the same flow rate
and temperature as the chamber drying in FY2020.
The drying performance and effects shall be verified
when enlarging the nozzle diameter to increase theairflow cross-sectional area and creating the same hot
air flow rate as the chamber method.

RUN③ Increase the numberof nozzles

The number of nozzles shall be increased and drying
treatment shall be conducted using the same flow rate
and temperature as the chamber drying in FY2020.
The drying performance and effects shall be verified
when increasing the number of nozzles to increase theairflow cross-sectional area and creating the same hot
air flow rate as the chamber method and further
creating near-uniform air direction conditions.

RUN④ Periodic operation

The effect of periodic hot air and decompression
drying shall be verified.

Values for gas flow rate and heater current will be obtained as equipment design data

© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

Drying time Note 1 vs
Moisture content rate Note2

Drying time Note 1 vs
Moisture content rate Note2

Drying time Note 1 vsCondensation/dew point

Drying time Note 1 vs
Moisture content rate Note246

©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.47

③ Implementation items and results(5) Study of test plan: Test case (1/2)

FY2019-2020 element test results showed that flow velocity affects the drying performance.
The improved canister proposal was examined to create the flow velocity equal to the chamber rating and to improve flow
path uniformity, and CFD analysis (ANSYS FLUENT v17.2) verified the improved flow velocity and flow path conditions.

① Current canister design(1 m/s)Flow velocity (Z = 420 mm)

Flow diagram* Inlet and outlet pipe diameter Φ7.5

② Improved canister 1(3 m/s)* Large diameter (Φ35)③ Improved canister 2(3 m/s)*Large diameter (Φ25) + increased
number of nozzles

Z = 420 mm

Improved flow velocity(flow rate) from ①
Large
Flow velocity(flow rate)
Small

Large

Flow velocity(flow rate)
Small

Small

Large

© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

0.52 to 1.4 m/s

1.4 to 4.4 m/s• Compared to the flow
velocity in the central
section of the current
canister design in ①
(cross-section ofcanister height 420mm), improved canister
1 in ② and improved
canister 2 in ③ show
faster flow velocity
throughout the entire
canister and bothdesigns are expected to
improve the drying
performance.
• Comparing ② and ③,③ is expected to have afaster minimum flow
velocity, improved
qualitative uniformity,
and to better facilitate
drying.

CFD analysis results
47

1.7 to 4.1 m/s©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.48

③ Implementation items and results(5) Study of test plan: Test case (2/2)
Classifi
cation RUN

Inlet/outlet pipe
Canister structure

Note 1⓪ Chamber
I

①
②

II

③
④

Cross- Heater surface/hot air
temperature (°C)
No. of sectional
diametereacharea(mm) (nozzles) (mm2)

Operatingmode Internal―

Hot air

Current structure
proposal
Modification 1(larger nozzle
diameter)
Modification 2(Increased numberof nozzles)
Current structure
proposal―Chamber/canister
heater output (kW)Flow velocity Note 2(m/sec)(Flow rate (Nm3/h))―

200

up to 10 Note 31(12)Hot air

7.5

1

44.2

200

up to 10 Note 31(12)Hot air

35

1 962.1

200

up to 10 Note 33(37)Hot air25

2 981.7200

up to 10 Note 33(37)Periodic
switching
betweenheating andvacuum

7.5

1

200

up to 10 Note 3

1(12)

44.2

Note 1: I ••• Verification of canister dryability II ••• Acquisition of data on changes in drying time Note 2: Flow velocity between canister and UC annulus section
Note 3: Output is automatically adjusted according to chamber heater surface temperature and canister inlet gas temperature

Larger nozzle
diameter(Larger flow rate)
Increased number ofnozzles(Larger flow rate,
improved airflow
uniformity)

Current structure proposal© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

Modification 1

Modification 2

Changed nozzle
position(Improved airflow
uniformity)

Not applicable(Dryability and drying performance with the same uniform airflow
conditions were obtained in the FY2019-2020 chamber test)48©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

Note 1: Hereafter, “② Design and manufacture of a canister for testingand design and modification of full-scale test equipment”
described in the implementation schedule (No.13) will beabbreviated as “design, manufacture, and modification of test
equipment”③ Implementation items and results

No.49(6) Design, manufacture, and modification of test equipment Note 1- The drying issues in the canister form (No. 45) were organized and it was veriﬁed that, compared to the FY2019-2020
chamber method, there is a flow deflection in the way the air hits inside the canister and that there is a limit to hot air
flow rate from increased pressure loss. To address these problems, a modification proposal that could be incorporated
without drastically changing the current canister design was examined (see the figure below), and the improved
canisters with different inner diameter of diffusion pipes (intake and exhaust pipes) and number of pipes were
examined. The improved canisters are being manufactured for full-scale testing.
- The body of the test equipment is being modified according to the plan in No.43 to 44.

Intake pipe

(Inner diameter)

Exhaust pipe
(Innerdiameter)(Innerdiameter)

Filter(Innerdiameter)

Filter(Innerdiameter)(Innerdiameter)

FilterInner
diameter ofdiffusion
pipe
Number ofdiffusion
pipes
ImprovementCurrent canister
designΦ7.5 mm

Improved canister1
Φ35 mm

Improved canister2
Φ25 mm1

1

2―

Improved to
Improved toincrease the inner increase the innerdiameter ofdiameter ofdiffusion pipes for a diffusion pipes andlarge flow rate.
further to increase
the number ofpipes, which resultin increased flowrate and improved
flow deflection.

Unit can (4canisters packed)(Notes)A hydrogen vent hole and a filter are installed in the canister lid, but because thehydrogen vent hole is closed during drying, the lid of a canister for the drying test will
not include the hydrogen vent hole and filter.

Figure: Illustration of the shape of canisters for drying test
© MITSUBISHI HEAVY INDUSTRIES、 LTD. All Rights Reserved.

49©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.50

③ Implementation items and results(6) Content of analysis (1/3)
The following items were studied by using the analysis model.
•

Drying time sensitivity evaluation and optimization studies using hot air anddecompression cycles in periodic drying©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.51

③ Implementation items and results(6) Content of analysis (2/3)•

The periodic drying method aims to temporarily increase drying rate by storing heat in moisture-containing
material during hot air and heater heatup and then suddenly converting that moisture into evaporation heatby rapidly reducing pressure.
In the FY2020 test, the temperature at the center of the unit can (UC) was only raised about 30°C and theeffect on increasing drying rate was not considered sufficient, so extending amount of time for hot air
heating was studied.
• Saturation temperature at chamber pressure• Center temperature of UC sample
Hot air 30 minutes Decompression 30 minutes (repeated)

Temperature [°C]•

(Tsat: saturation
temperature)
101 kPaA,
Tsat = 100°C
T= ?
Increase initial
decompression temperatureby extending hot air time

4.2 kPaA,
Tsat = 30°C(= temperature of
FY2020 sample)
1 kPaA,
Tsat = 7°CTime [hr]FY2020 Periodic drying test
Figure 1: Change of saturation temperature and UC temperature atchamber pressure over time
(An expanded time scale of the first half of drying)

Start ofdecompression

FY2020Plan for FY2022

The amount of evaporation
during decompression
increases by increasing thetemperature increases
Water’s sensible heatis converted into
evaporation heat.

30 minutes ofdecompression

Figure 2: Schematic diagram of the relationship between
pressure/temperature changes and evaporation©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.52

③ Implementation items and results(6) Content of analysis (3/3)

Amount of evaporation [g/s]

2.2 times for 30℃

1.8 times
1.4 times

2 times for 30°C
1.7 times
1.4 times

Sample temperature [°C]Sample temperature [°C]

Relationship between sample temperatureand the amount of evaporation during
periodic drying and decompression

Sample temperature and temperaturerise time during periodic drying andheatupStudy of the amount of evaporation fromthe rate of decrease for water enthalpy
Δh during decompression and coolingprocesses W [kg/s] = Δh [J/kg/s] ×moisture content rate [kg]/latent heat
[J/kg]

Study using one-dimensional unsteadystate heat conduction calculations in
the radial direction of a unit canFigure 1: Estimated results based on FY2020 test

Improved operation(periodic)
2020 operation(periodic)
2020 operation (hot air)Moisturecontent rate(%)•

Moisture content rate(%)•

The objective is to increase the drying rate during decompression by raising the temperature of the sample. However,
if it takes too long to preheat the sample, then there will be no reduction to the time required for the entire drying
process.
When raising the temperature of the sample to 60°C, the effect is doubled in the amount of evaporation, but twice
as much time is required to raise the temperature (Figure 1). As it stands now, 0.5 hr temperature rise + 0.5 hr
decompression = 1 hr/1 set ⇒ 1 hr temperate rise + 0.5 hr decompression = 1.5 hr/1 set. Considering the two
together, doubling of the amount of evaporation for a 1.5 increase in time per set can be expected to increase thedrying rate by 1.3 times. (There is an upper limit on water’s boiling point during preheating, so there should be a limit
to the effect of raising the temperature.)
It is assumed that the above effect is small in the latter half of drying, when the influence of fine pores in zeolite isthought to be prominent. Applying the above effect to the data up to 9.5 hour mark (the assumed first half of drying),
the time reduction of 9.5 - 9.5 / 1.3 = 2 hours can be expected. However, based on the drying end time in the test,
drying time was shortened by about 1.5 hours (Figure 2).
Temperature rise time [min]•1.5 hr reduction(Test results)

0.3wt%
Drying time

Drying time

Figure 2: FY2022 Periodic drying test Change in moisture content rate over time
Comparison with FY2020 test
©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.53

③ Implementation items and results(7) Summary• The concepts of canister drying, the details of test using full-scale test equipment, therange of necessary modifications and the test conditions for the canister were studied,and the canister drying test was planned. (No.40 to 48)⇒ Pressure loss is large with the current canister structure and sufficient airflow ratecannot be secured.
⇒ The required canister structure will be organized for drying treatment in accordancewith the guiding policy.
• Canisters for testing and full-scale test equipment are being designed and manufactured
according to the canister drying test. (No.49)• The improved operation proposal for periodic drying operations in FY2019-2020 was
analyzed and studied. The verification operation test was conducted. (No.50 to 52)⇒ The treatment time is expected to reduce by approximately 1.5 hours.

©International Research Institute for Nuclear Decommissioning6.2 Full-scale test

No.54

➃ Contribution of outcomes to relevant study areas• The requirements for canister specifications will be consolidated to contribute to thestudy of countermeasures for hydrogen generation during transfer of the containerin future.

⑤ Analysis with respect to on-site applicability• Equipment specifications will be examined from the perspective of on-site
operations, such as presenting optimum operating conditions.

⑥ Issues• There are no issues in executing the current plan.

⑦ Goal achievement level• A specific test plan has been proposed and equipment and canisters for testing arebeing prepared. The desired results are expected to be achieved according to theplan.

⑧ Future plans• In FY2022, the modification of full-scale test equipment, expansion of the data via fullscale test, sensitivity evaluation of drying time by analysis, and actualization of thedrying concept based on the results of tests and analysis will be implemented.
• Based on the acquired data, the concept of canister drying equipment, the optimum
operating conditions for canisters, and the evaluation for advantages anddisadvantages compared to the chamber method, as well as issues when applying
multiple treatments will be studied.
©International Research Institute for Nuclear Decommissioning7. Summary

No.55• Tests for the proposed results of element tests (data on the drying characteristics of slurry, sludge,
and concrete) are being planned and implemented. Data on the sample temperature distribution
and moisture content rate change in full-scale drying for slurry and sludge, and data on the physicalcharacteristics and the sample temperature distribution and moisture content rate change in the
beaker scale for concrete, are being obtained and studied on an ongoing basis.
• The proposed results of element tests (the range of application (the materials to be dried) for the
drying concept and alternative methods and means for the materials that are difficult to dry) will be
reviewed and the results will be obtained in FY2022 based on the above test results.

• Based on the proposed results of full-scale test (results of verification test in the canister form),issues in modifying test equipment were extracted and the studies of modified test equipment,
canisters for testing, and test conditions were conducted. As a result, test conditions that factor inpressure loss were determined and the manufacturing of canisters and modification of test
equipment are in progress. The test will be conducted in FY2022 to obtain these results.
• For the proposed results of full-scale test (the concept of canister drying equipment, the optimum
operating conditions for canisters, the evaluation for advantages and disadvantages compared tothe chamber method, issues when applying multiple treatments, and the requirements for canister
design), the analytical evaluation and the verification test were conducted to review the cycle ofperiodic drying for the study of optimum operating conditions, and improvements from FY2020
operations were verified. The rest will be examined in FY2022 based on the above test results andresults will be obtained.
©International Research Institute for Nuclear Decommissioning

No.56

Reference materials©International Research Institute for Nuclear Decommissioning6. Implementation details
6.4 Development of drying technology and systems(1) Study of basic specifications for drying equipment③ Implementation items and results (estimated and actual)a. Study of basic conditions (1/2)
i. Clarification of performance requirements

Reference material (target moisture content rate)
Excerpt from “Subsidy Project of Government-led R&D
Program on Decommissioning and Contaminated Water
Management in FY2018 Supplementary Budget(Development of Technologies for Containing, Transfer, andStorage of Fuel Debris)” Final Report FY2020 (June, 2021)

No.57
No.57

Objects to be dried and target process time and moisture content rate were set as described below as performancerequirements for the drying system.
(Material to be dried) Porous media. Based on the fact that collected materials at TMI-2 were porous media.
Zeolites, known as representative porous media, are used for the test.
(Target process time) 24 hours from loading to unloading(Target moisture content rate) 0.1 wt% Note 1
Table: Evaluation of performance requirements
Performance requirements

Note 1: Moisture content rate
premised on fuel debris
density.
It will be revised based on
the density of the zeolite test
sample used for the test.
Nov 11, 2021 postscript
In element tests, target moisture content
rate is determined by converting thedensity of the material to be dried.
- Slurry and sludge (silica sand): 2.6
g/cm3 → converted value of 0.2 wt%- Concrete: 2.3 g/cm3 → converted valueof 0.2 wt%(Could be revised depending on thesample used)

Target items

Target timeTarget moisture
content rate

It should deal with theproperties of fuel debris
collected at the retrieval side

Description of target
The target object is porous media with small pores.
Although slurry might be subject to drying, considering
the fact that their current properties are unknown, theapplicability of the drying technology to be consideredin the main target will be examined through element
tests, etc.

It should be handled by aConsidering their handling in unit cans or canisters
method allocated from theretrieval sideIt should dry within the time
The assumed target time from receiving to allocation iscorresponding to the throughput 24 hours.
the fuel debris retrieved
The volume of residual water
should be reduced as much as
possible after drying.

The target moisture content rate is set to 0.1 wt%
estimating a margin on the moisture content rate (1.5
wt%) where the hydrogen concentration in the canisterreaches the lower explosion limit (4 vol%) during thetransfer period of 7 days.
©International Research Institute for Nuclear Decommissioning6. Implementation details

Reference materials (FY2019-20 Implementation details:
element tests)
Excerpt from “Subsidy Project of Government-led R&D
Program on Decommissioning and Contaminated Water
Management in FY2018 Supplementary Budget(Development of Technologies for Containing, Transfer, andStorage of Fuel Debris)” Final Report FY2020 (June, 2021)

6.4 Development of drying technology and systems(1) Study of basic specifications for drying equipment

No.58
No.58

③ Implementation items and results (estimated and actual) b. Collection of drying behavior data (2/6)
i. Element tests [Test results] - Understand the sensitivity of the operation parameters during hot air and decompression drying
Temperature, pressure, and gas flow velocity significantly affect drying performance

Run 2 (airflow: 100°C, 3 m/s)
Run 3 (airflow: 200°C, 1 m/s)

Test duration (h)Objects to bedried

Run 7 (SUS beads)

Zeolite1(Degree ofporosity: 38%)

Density[g/cm3]

Thermalconductivity[w/mK]

Filling rate[%]

SUS beads*2
Silica sand

47 (same particlesize)
52 (mixed particle
diameters)*1: Actual measurements *2: From the website of Japan Stainless Steel Association(http://www.jssa.gr.jp/contents/)*3: As per JIS Z 8901 *4: Values for soda lime glass cited from Handbook ofChemistry, Revised 5th Edition, published by Maruzen Publishing Co., Ltd.

[Test results]
Moisture content rate
Figure: Drying characteristic curves from
impact assessment of materials to be dried

Run 5 (decompression: 100°C, 1 kPa-A)
Run 6 (decompression: 200°C, 50 kPa-A)- Thermal conductivity and the presence offine pores significantly affect drying
behavior- Understanding of fuel debris properties:
Thermal conductivity, fine pore diameter,
particle size, etc.

Test duration (h)Test duration (h)Figure: Decompression drying element test
Change in moisture content rate over time
Run 1 (zeolite)

Drying rate (g-H2O/m2-s)

Drying rate (g-H2O/m2-s)

Run 1 (zeolite)

Run 9 (silica sand with mixed
particle diameters)
Run 10 (zeolite + SUS beads)

Run 4-2 (decompression: 200°C, 1 kPa-A)

Test duration (h)Figure: Decompression drying element test Change in moisture content rate overtime
Table: Physical properties of materials to be dried

Run 8 (silica sand)Run 4-1 (decompression: 200°C, 1 kPa-A)

Moisture content rate of test samples(–)

Run 1-2 (airflow: 200°C, 3 m/s)

Moisture content rate of test
samples (–)

Run 1-1 (airflow: 200°C, 3 m/s)

Moisture content rate of test samples (–)

Moisture content rate of test samples (–)- The end point of drying is achieved in approximately 13 hours for both methods  There is a possibility ofachieving the 0.3 wt% target moisture content rate with airflow drying

Run 1* (zeolite, mesh)

Run 11 (zirconia, mesh)

Table: Physical properties ofslurry (zirconia)
Items

Value

Material
Particle size
Density
Thermalconductivity
Specificsurface areaSS
concentration

External
appearance ofslurry3.3wt% Note 1

Filling rate

Moisture content
rate

Note 1: Moisture content rate ofand mesh at 24 hours
Figure: Drying characteristic curves from slurry zirconia
from the start of the test

hot air drying test
[Test results] Air layers were formed between particles after drying slurry with a low
filling rate
Research
Institutefor Nuclear Decommissioning
The drying rate decreased ©International
due to decreased
thermalconductivityof the test sample
surface③ Implementation items and results (estimated and actual)b. Collection of drying behavior data (3/6)
i. Element tests[Evaluation method]① Reverse calculation of effective diffusion coefficients from test data using a drying process evaluation model (De′)② Comparison of obtained De′ with the theoretical values of the steam diffusion coefficient in the layers concerned〇 Evaluation results (1/2)(1) In the first half of the drying period: De′/De>1- Drying rate was greater than water vapor diffusion rate
- It was inferred that liquid water diffused toward the surface and facilitated the drying process. (The diffusion
coefficient was estimated higher in the model)(2) In the second half of the drying period: De′/De<1- Slow drying in fine pores was inferred to be a cause (based on the results of tests with SUS beads having no finepores not indicating this tendency)- This tendency was most prominent in decompression drying
Influence ofthe movementof liquid water

Comparison between
drying methods

Vapor
diffusionComparison between
materials to be dried

Influence of finepores

Zeolite hot air drying

Zeolite hot air drying

Zeolite decompression drying

SUS beads hot air drying

Moisture content rate
[wt%]

Moisture content rate
[wt%]

Figure: Results of estimations of effective diffusion coefficients
based on element tests

Vapor pressure in fine pores/standard
vapor pressure pv/PΦ [–]6.4 Development of drying technology and systems(1) Study of basic specifications for drying equipment

Reference materials (FY2019-20 implementation details:
analytical evaluation)
Excerpt from “Subsidy Project of Government-led R&D
Program on Decommissioning and Contaminated Water
Management in FY2018 Supplementary Budget(Development of Technologies for Containing, Transfer, andStorage of Fuel Debris)” Final Report FY2020 (June, 2021)

No.59
No.59

Range of zeolite fine pore diameter

Drying surface
temperature: 150°C
Drying surface
temperature: 100°C
Drying surface
temperature: 50°C

Fine pore diameter[nm]

Figure: Relationship between fine pore
diameter and vapor pressure
Drying rate [mg/(mm2-hr)]

6. Implementation details

Drying is possible at a
relatively low
decompression level if thetemperature is raised

Sampletemperature
7°C
Sampletemperature
100°C

Range ofsatisfactory
dryingperformance

Vapor pressurein fine pores at
7°C

Atmospheric pressure [kPa A] Vapor pressure infine pores at
100°C

Figure: Relationship between atmosphericpressure and drying rate indecompression drying〇 Evaluation results (2/2)- Atmospheric pressure is approximately 1/100 to 1/10 vapor pressure at a fine pore diameter of 0.4
to 1 nm- Moisture in fine pores cannot be dried at low temperatures (approximately 7°C at drying surface)and 1 kPa A of pressure- The treatment method of sufficiently heating the material to be dried and decompressing inside thedrying chamber is effective©International Research Institute for Nuclear Decommissioning6. Implementation details

Test conditions

Drying time

Moisture content
rate (wt%)*1#0

Hot air

14:00

0.31

16:00

<0.12

16:00

<0.13

14:00

<0.15

#1
#2
#3-1

Periodic switching
between heating andvacuumHot air with unit cansdecentered
Periodic switching,
85% filling rate

#3-2

Hot air, 85% filling rate

12:00

0.21

#5

Vacuum

16:00

2.54

Note 1: Moisture content rate = Moisture content rate (g)/Absolute dry weight (g)The absolute dry weight in the test was approximately 16 kg (total of 4 UCs with 100% fillingrate)• The target moisture content rate of 0.3 wt% or less was achieved in approximately 14 hours with
100% filling rate
• Comparing drying methods, about the same performance was obtained in hot air and periodic
switching drying, whereas a longer drying time was required with decompression drying• Roughly the same results were obtained even when the UCs were placed decentered → The
influence of flow velocity distribution in the dryer chamber is small• Decreased filling rate resulted in decreased drying time →This can be explained by a lower initial
volume of water.Note 2

Note 2: Drying time decreased to 85% when the filling height was reduced to 85%.

Moisture content rate (wt%)

No.

Reference materials (FY2019-20 Implementation details:
full-scale test)
Excerpt from “Subsidy Project of Government-led R&D
Program on Decommissioning and Contaminated Water
Management in FY2018 Supplementary Budget(Development of Technologies for Containing, Transfer, andStorage of Fuel Debris)” Final Report FY2020 (June, 2021)

Comparison ofdrying methods

No.60
No.
60

#0_Hot air#1_Periodic
switching#5_decompre
ssion

Drying time

Moisture content rate (wt%)

6.4 Development of drying technology and systems(1) Study of basic specifications for drying equipment③ Implementation items and results (estimated and actual)b. Collection of drying behavior data (6/6)
iii. Collection of handleability and drying behavior data
Table Results of full-scale test

Figure Comparison of drying methods withrespect to moisture content rate change overtimeair (filling rate: 100%)#0_Hot#2_Hot air (filling rate: 100%,
unit cans decentered)#3-2_Hot air (filling rate: 85%)

Comparison with respect tofilling rate and unit canplacement: Hot air

Drying time

Figure: Comparison of change in moisture content
rate over time in hot air drying with respect to fillingrate and unit can placement©International Research Institute for Nuclear DecommissioningNo.61

Reference: Definition of the absolute dry weight for each sample
SampleDefinition of absolute dryweight in this project

ZeoliteWeight when heated toSlurry and sludge
300°C and held for at least(silica sand)5 hours
Concrete

Theoretical value ofSlurry and sludge
product at test condition(flocculant)
temperatures

Absolute dry measurement
methodHeat the test sample to 300°C for atleast 5 hours and then measure theweight after simple isolation
cooldown Note 1
Calculate the theoretical value ofthe product from the amount ofreagents used in the test
(200°C: Al(OH)3 + Na2(SO4),
300°C: Al2O3 + Na2(SO4))

Note 1: Simple isolation cooldown: Cooldown in an isolation container with a desiccant like silica gel installed in the vent©International Research Institute for Nuclear Decommissioning