WRFPM 2014
Sendai, Japan

Research and Development Programs forDecommissioning of Fukushima Daiichi Nuclear
Power Station
September 15, 2014

KENDA Hirofumi
International Research Institute for Nuclear Decommissioning*The contents of this presentation include the results of “Establishment of basic technology for decommissioning and safety of nuclear reactors for power generation in 2013(technological study and research concerning forming an idea for processing and disposing of radioactive waste resulting from the accident)“, a project commissioned by theMinistry of Economy, Trade and Industry, and the 2013 subsidiary for decommissioning and contaminated water measures (development of technologies for processing anddisposing of waste resulting from the accident).
*Plant information included in this document is taken from TEPCO’s official website.

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Outline of IRID
1. NameResearch & Development Consortium,“International Research Institute for Nuclear Decommissioning”(IRID)
2. Location of Main Office
6F, Parkplace, 5-27-1, Shimbashi, Minato-Ku, Tokyo, 105-0004, Japan(http://www.IRID.or.jp)

3. Founding Members (18)- Incorporated administrative agencies:
Japan Atomic Energy Agency,
National Institute of Advanced Industrial Science and Technology.

- Manufacturers:
Toshiba Corporation, Hitachi-GE Nuclear Energy, Ltd.,
Mitsubishi Heavy Industries, Ltd., ATOX (since May 29, 2014).

- Electric utilities etc. :Hokkaido Electric Power Company (hereinafter called as EPC), Tohoku EPC,Tokyo EPC, Chubu EPC, Hokuriku EPC, Kansai EPC, Chugoku EPC, Shikoku EPC,
Kyushu EPC, The Japan Atomic Power Company, J-POWER,
Japan Nuclear Fuel Limited.
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Projects of IRID
IRID gathers knowledge and ideas
from around the world for thepurpose of R&D in the area of nuclear
decommissioning under theintegrated management system.

R&D for
Decommissioning

R&D projects:･Investigation of damaged PCV
and preparation of repair tools･Preparation for fuel debris
retrieval･Treatment and disposal ofradioactive waste

Promotecollaboration for
Decommissioning
with Domestic andInternational
PartiesDevelopmentof Human Resourcefor R&D

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3Decommissioning of Fukushima Daiichi NPS
Government
・Supervise overall decommissioning projects
・Decide Decommissioning policy（long-and-mid term Road Map）

Important issues

direction, advice, etc.

ReportNuclear Damage Compensation andDecommissioning Facilitation Corporation

funding for R&D

1.Strategy planning for major issues
2.R&D planning
3.Management support for R&D projects

Operate Decommissioning WorkTEPCO Fukushima Daiichi D&DEngineering Company
Operate decommissioning work, manage worksafety and develop site applicable technology, etc

Mutualcooperation

Execute R＆D

IRID
Develop critical decommissioning technologies in
mid and long term (as National Project)

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4Organizational Chart （2014.8.19～）
General Meeting
Board of Directors
Technology Advisory
Committee

R&D Management
Department

International Advisors
Fuel Debris Technical Assessment Team

Administration
Department

R&D Strategy Planning
Department

Research Project & Information
Management Team

Development Planning Office
Technical Strategic Planning
Team

International Cooperation
Team
Corporate CommunicationsTeam

PCV Investigation andRepair Technology GroupFuel Debris Retrieval
Technology Group

Administration & HumanResource Management Team
Accounting & Procurement
TeamGeneral Management Team
Human Resource
Development & Academia
Cooperation Team

Reactor Interior andFuel Debris Evaluation
Technology Group

Structural Integrity
Assessment TechnologyGroupRadioactive Waste
Treatment and Disposal
Technology Group

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December 2011
(Roadmap established)
Efforts to stabilize
plant condition<Achieve coldshutdown>• Cold shutdown state• Significantly reduceradiation releases

2020-November 2013

Phase 1

Phase 2

Period up to thecommencement of
the removal of thefuel from the spent
fuel pool (within 2years)

Period up to thecommencement of theretrieval of the fuel debris(within 10 years)

30 to 40years
in the future

Phase 3
Period up to thecompletion ofdecommissioning measures(30 to 40 years in thefuture)

Now
Having completed Phase 1 of Mid-and-Long-Term Roadmap, R&D will be addressed as follows fromthe Phase 2.
1. Promotion of long-term R&D in response to the start of fuel removal from spent fuel pool.
2. Development of multilateral, multilayered method and equipment for full scale preparation offuel debris retrieval(1) - Submersion method- .
3. Development of multilateral, multilayered method and equipment for full scale preparation offuel debris retrieval(2) - Alternative method- .
4. Stable promotion of R&D inconsideration of treatment and disposal of radioactive waste, anddecommissioning.
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6R&D Activities of IRID
■ R&D activities should be carried out considering severe conditions of reactor
buildings at Fukushima Daiichi.
High dose rate

High temp.

High humidity

RubbleElevated places

Underwater

Narrow places

Sea water

R&D for fuel removed fromspent fuel pools

DS pitSpent fuelpool
Steam Dryer
SteamSeparator

Reactor pressure
vesselEquipment Hatch

R&D for preparation forfuel debris retrieval

Debris

R&D for treatment anddisposal of radioactivewastePrimary
containment vessel
Torus room

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Concept of work steps for fuel debris retrieval■The approach of retrieving the fuel debris submerged in water is the safest
approach from the standpoint of minimizing exposure of workers.
■Technologies for investigation and repairing methods for filling the PCV
with water are under development. Furthermore R&D for retrieval, packing
and storage of fuel debris are implemented.
■Request for Information(RFI) on alternative methods for the fuel debris
retrieval was conducted.
Retrieval of fuel debris
Repair of lower part of PCV
Drain stoppage →Water filling

Overhead crane

Building cover
Fuel debris can container
RPV lid

Spent Fuel
Pool (SFP)

Spent Fuel
Pool (SFP)

Reactor RPV

Filling waterRetrieval

Reactor RPV

PCVStopping drain
Torus room

PCV

Torus room

PCV

Torus room

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Major Challenges in the Existing Decommissioning Procedures
 Final goal is to remove all fuels and fuel debris from Reactor Building (R/B).
 Removing procedure would be much more complicated than TMI-2 due todifferences shown below:
TMI-2

Fukushima Daiichi

R/B Damage

LimitedDamaged by H2 explosion(Units 1,3,4)Water Boundary

RV remained intact

Both RPV/PCV are damaged(Units 1-3)

Fuel Debris Location

Remained in RV

Possibly fallen out of RPV

Bottom of the Vessel

No structural components

Complicated structure including
Control Rod Drives

 Many of TMI-2 experiences can be utilized for fuel removal anddecommissioning of Fukushima Daiichi.
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Current status of lower part of PCV【Unit 1】

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10Current status of lower part of PCV【Unit 2】

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Current status of lower part of PCV【Unit 3】

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Investigation of status inside PCVInvestigation equipment of grating on the 1st floor outside pedestal(1)Overview of equipment
Shape-changing crawler equipment is inserted from the narrow access entrance (X-100B penetration opening：
φ100mm) and safely travel on grating stably.

(2) Image of investigation route and equipment
X-100BD/W 1st Fl. grating

Traveling through piping

Existing guide piping

Traveling direction

X-100B

Board camera*Use whentravelingthroughpiping.

Existing guide piping

Composite cableCrawlertransformation
Traveling on gratingThermometer*Installedinside cover

D/W basement FlＰＣＶ
X-6：Investigation route (Plan) （※１）

[Cross Section of PCV]

*１ Investigation route and area are images andmay change depending on the condition of the PCV.

High doserate【Ｄ/W 1st Fl.】Internal PCV investigation route (Plan)

Camera forinvestigation

Features of equipment

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Fuel debris identification by muon observation technology
Permeation method

Scattering methodMuonMuonMuon detector
Incidence
angle

Muon
detector
Object to bemeasured

Object to bemeasured

Permeation ratio is measured.

Emitting
angle: Detecttion element

Scattering angle is measured.

Presence of matters in coming direction(two-dimensional)

Presence of matters at scattering position(three-dimensional)

Identifying ability (fuel debris): About 1 m

Identifying ability (fuel debris) ： About 30 cm

One small-size muon detector (applicable early)

Two large-size muon detectors(need to be developed)
Can identify heavy elements such as uranium.

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Test results (muon permeation method)
Results of measurement at Tokai No. 2 nuclear power plant of the Japan Atomic Power Company:
・No fuel in nuclear reactor
・Fuel existed in spent fuel poolMark-II PCV
and reactor inbuilding

Reactorbuilding

Detector 2-2

Detector 3

Detector 2-1

Detector 2-1

Measurement positions at Tokai No. 2nuclear power plant:(3 points)

Detector 2-2

Detector 3

Measurement result at each pointHigh-density substance existed outside frustum-shaped PCV
KEK(High Energy Acceleration Research Organization)data

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Analysis of characteristics using mock debris
Fe-Cr-Ni(Fe,Cr,Ni)2B

ZrB2（Foil-like or (Fe,Cr,Ni)2(Zr,U)flat crystal structure) (Fe2ZrType Cubic）

Arc melting

Oxidative atmosphere(annealing)（ Ar-0.1%O2,1500℃）

Fe-Cr-Ni(Zr,U)O2 (Zr-rich)（Alloy andZrB2Oxidized）

Reaction with control material（ B4 C+SUS) （Example of the fusion solidification abstaining from side observation image（ Obtained knowledge regarding the composition of solidified material generated when control rod and molten fuel ）Vickers hardness of each formed aspect
BorideGlassinessOxidizer(Sintering)(Sintering,15-75%U)

Metal
Vickers hardness（Estimate hardness distribution for each chemical system of fuel debris (boride, oxide, metal）
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Retrieval of Fuel Debris (Plan A)◎ Technical method study
Retrieval scenario should be established considering
information on the plant status, development of related
technologies and investigation results.
→ Many information will be comprehensively evaluated andunclear points should be assumed.
→ Investigation of existing technologies is made in thisproject.

Cell, etc.
Work cart◎ Areas to be developed for retrieval of fuel debris
Areas common to retrieval of fuel debris, regardless of various“Plans”, are as follows:

Remotely operated arm

1) Cutting fuel debris
2) Remote operation
3) Prevention of expansion of contamination
4) Shielding5) Criticality prevention

Isolation film sheet
Shielding

DSP

SFP debris
canisterLong arm
Cutter, camera,
handling tools◎ Element tests
Element tests for cutting fuel debris, remote operation, andprevention of expansion of contamination are made.

(1) Cutting fuel debris
1) Test to cut ceramic specimen
2) Production of specimen(2) Remote operation
1) Long arm control technology
2) Production of remote operated arm(3) Prevention of expansion of contamination
1) Selection of isolation film sheet（Image of Retrieval method
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17Plan B
Operating device(Shielding plug)

100t class overhead craneBarrierContainer

Ventilationequipment

Operation floor
Operating device(telescope etc)

Spent fuel pool

DS pitOperatingdevice
Cutting device
Visual device
etc.

RPV

Ventilation equipment

PCV
約35m

Extension/contraction

Major issues
・Ensure boundaries
・Setting precision of therotating plug・Control of repulsive force
during cutting

Torus room

Method to retrieve fuel debris in air by rotating plug
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18Plan C
100t class overhead craneOperating device(gate type crane etc. )Ventilationequipment

Container
Operation floor
Spent fuel pool

Barrier with shielding
function

DS pitCutting device
Operatingdevice
Visual device
etc.

Descening platform

RPV
Ventilation equipment

PCV

Major issues
・Ensure boundaries
・Radiation shielding
during operations

Torus room

Method to retrieve fuel debris in air by descending work platform
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19Plan D
100t class overhead crane

Major issues
・Ensure boundaries
・Radiation shielding
during operations
・Location of entrance
opening

Container

Operation floor

DS pitSpent fuel pool

Existing equipment hatch/new
opening

Operating device
Cutting device
Visual device etc.

Barrier with shielding
function

RPV

Ventilationequipment

PCV

Torus room

Ventilationequipment
Operating device
Operating device

Access route

Method to retrieve fuel debris in air from the side
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Conclusion
 In order to accomplish fuel debris retrieval, total optimizationof the plan is essential. For that purpose methodology andtechnologies should be flexibly combined while purpose andobjective of each Fukushima R&D program are clearly
identified.
 Fuel debris retrieval of Fukushima Daiichi is much moredifficult than that of TMI-2. In establishing overall strategy
and developing retrieval tools, it is necessary to gather
knowledge and information domestically and internationally.
 In establishing strategy, it is important to define the “EndState”. Towards that End State alternatives should be
prepared or made available in various stages.
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