JAEA R&D Efforts for Decommissioning of
the Fukushima Daiichi NPSInternational Topical Workshop on
Fukushima Decommissioning Research 2022&
The First 2022 Fukushima Research Conference
October 15, 2022, J-Village, Fukushima

Kentaro Funaki
Sector of Fukushima R&D
Japan Atomic Energy Agency

1. Introduction1

Mission: Three core pillars
R&D for Environmental
Restoration of Fukushima

R&D for Decommissioning

Building R&D Base/Platform- facilities- human networks etc.
Contributing to Fukushima Revitalization- Collaboration with local stakeholders- Working with local industry- Human resource development

2

History
Organization Chart

NARREC launched(Naraha town)

Sector of Fukushima R&D

Okuma Analysis and Research Centerlaunched (Okuma town)

Planning and Co-ordination Office“Laboratory-1”

Fukushima Research Institute
Safety Administration
Department
Fukushima Administrative
Department

Collaborative Laboratories for Advanced
Decommissioning Science (CLADS)
Naraha Center for Remote Control
Technology Development (NARREC)

Great East Japan Earthquake

Apr.2014

Fukushima Daiichi NPS (1F)
Accident

2018

Reorganization as“Fukushima R&D
Sector”

Dec.2011“Administrative Building”

2022

Okuma Analysis and Research Center

HistoryMar.2011

2017
2016

2015

Mid-and-Long-Term
Roadmap was established

2014

2013

2011

Fukushima CEC started
research activities(Miharu Town)“Nuclear Plant
Decommissioning Safety
Research Establishment”
was established
JAEA joins IRID

Iwaki Office opened
Fukushima CEC started
research activities(Minamisoma City)

2020
Decommissioning
research units andenvironmental
restoration units
were integrated as a
new "CLADS"

CLADSʼ “International Collaborative
Research Building” launched

JAEA started supports for environmental monitoring,decontamination activities and the national and local
governments immediately after the 1F accident“Headquarters of Fukushima Partnership Operations”
was established“Fukushima Office” opened

Environment
monitoring

Decontamination

Internal exposure test

Information session
for public

3

R&D sites/facilities for Fukushima R&D
Fukushima Daiichi Nuclear Power Station

R&D for environment restoration

R&D for decommissioning

CLADS at Fukushima CEC* (2 sites)

Okuma Analysis and Research Center• Environmental dynamics
research• Environmental monitoring• Development of analytical methods• Characterization ofradioactive waste andfuel debris

Fukushima*Fukushima CEC :Fukushima prefectural Centre for Environmental Creation

IbarakiJAPAＮ• Headquarter of JAEAʼs Fukushima R&D• Severe accident analysis• Waste management• Remote visualization
NARRECTokyo

Fukui(Tsuruga)

Collaboration throughout JAEA
R&D sectors and facilities

Other JAEA sectors/centers
Sector of Tsuruga
Decommissioning
Demonstration

CLADS• Mock-up test andtraining• Robot simulator• Virtual reality system
HeadIbaraki
quoter ofarea
JAEA(Tokai and Oarai)
Nuclear Science Research Institute

Aomori Research and Development Center

Nuclear Fuel Cycle Engineering Laboratories

Materials Sciences Research Center

Oarai Research and Development Institute42. JAEA Roles for Decommissioning R&D

Y. Sato et. al., J. Nucl. Sci. Technol. 2019; 56: 801–808.

55

Organizations involved in decommissioning R&D

PolicyGOJ
NDF

Regulatory Authorities(Nuclear Damage Compensation andDecommissioning Facilitation Corporation )Strategy

IRID(R&D consortium)

JAEA(National lab)

TEPCO HD

DeliveryR&D+
R&D platform

Research Institutions &Universities

International alliance partners/academic society
6Mid-to-long-term R&D plans

Interrelation of strategic documents for decommissioning R&D
NDF Technical Strategic Plan

Mid-to-Long-Term R&D Plan

NDF

METI-funded R&D

Coordination

Identify key R&D areas/topics for the long-termand reflect into each strategic R&D plans
further coordination

TEPCO
Coordination

Mid-to-Long-Term Decommissioning
Action Plan
Coordination(Identification of technology development issues
related to the above plan)

JAEA
Decommissioning Science Diagram(Mainly for basic and fundamental R&D)

MEXT Research grant for
Decommissioning Science(Mission H)
7

Decommissioning Science Diagram
mainly for basic and fundamental R&D

8R&D scope of JAEA/CLADS

9

Remaining challenges and R&D needs
At the Fukushima Daiichi site, some progress has been made, ……
But, there remain unpresedended challenges ahead for the long run.
üüüü

A large amount of radioactive materials, remaining unsealed and unknown
Incomplete barriers for containment
Uncertainties on the state of radioactive materials and containment barriers
Difficulty in an access(Source: NDF Technical Strategic Plan 2021)

R&D Needs
Ø Collect, consolidate, and analyze data
Ø Characterization and visualization
Ø Methodologies for safety and risk assessment

Goal !!

“Sherpa guide” for“the mountain climbing team”！

10Backcasting approaches

Baseline analysis

Future vision

What we have achieved during
the past years︖(e.g. R&D outputs/outcomes)

What we need to achieve
by around 2030︖(e.g. our mid-term goal)

Forecasting

Backcasting！ and solutions
Prioritization of actions
Priority R&D issues/topics for the upcoming years(e.g. ”JAEA mid-to-term R&D plan for FY2022-2028”)11

3. Fuel Debris Retrieval R&D

引⽤︓METIホームページ

1212Fuel Debris Retrieval R&D
n Near-term goal: launch the first retrieval operations from Unit 2
Actions/solutions

Backcastingn JAEA R&D focuses/priorities■ 2030 vision: ideal state(to be discussed further)
1. Trial fuel debris retrieval
from Unit 2 progressed, andlarger-scale retrieval from
Unit 3 nearly ready.

p Estimation of PCV internal
condition and fuel debris
characterization

2. Fuel debris analysis (incl.
non-destructive methods)
becomes well readyp Safety/risk assessment forfuel debris retrieval operation

3. Methodologies for safety andrisk management
establishedp Analysis of fuel debris
13Fuel Debris Retrieval R&D

Preparation for launching fuel debris retrieval and R&D needs
〜2022

Year

Internal investigation, Estimation of core status,
Development of analysis methods

2023〜
Start fueldebris retrieval(Unit 2)(~g order)
Dose rate
Meas.

Image

Dose rateestimation

1F sample（Sediment etc.）

METI-funded R&D project (subsidy for research institutions)for decommissioning and contaminated water management- Mainly for initiating trial retrieval of fuel debris ① Development of analysis and estimation technologies
for characterization of Fuel Debris② Development of technologies for enhanced analysis
accuracy
JAEA basic and fundamental research (MEXT-funded)- Mainly for safety and risk management from fuel debris
retrieval, transfer to storage, with longer-term perspectives③ Evaluation of dose distribution④ Material accountancy, non destructive measurement⑤ Elucidation of aging degradation of fuel debris⑥ Fuel debris storage and management technology⑦ Corrosion under peculiar environment

Expand the scaleof retrieval gradually (Unit 2)(~kg order)(Total ~880t)

Temporary storage→Long-term stable storage

R&D priorities for the mid-to-long-term
・ Establishment of analysis and evaluation methods including
non-detractive assay technology for fuel debris ranging fromextremely small amounts to macroscopic amounts.
・ Development of the sorting technology for fuel debris andradioactive materials
・ Accumulation and organization of knowledge that contributes
to understanding fuel debris characteristics（Generation mechanism, Aging degradation, Radioactive
particle, etc.)
・ Development of material accountancy measures
・ Fuel debris storage and management technology（Evaluation of radiation effect, Radiolysis, H2 production,
Material corrosion, H2 explosion , etc.）
・ Safety assessment for disposal（H2 production, Corrosion, Aging, Exothermic property, Longterm stability, etc.）

14

Fuel Debris Retrieval R&D

Preparation for launching fuel debris retrieval operations
Process during and after fuel debris retrieval

Pebble
type
Crust
type

Storage building

Storage pool

Stump

Stump
type
type

OR

Canister
MCCI
type

CanisterCask

Dry storage

Cask

Fuel debris retrieval

BufferCanister

Wet storage

Temporary storage

Estimation of PCV
internal condition

Processing anddisposalR&D Topics
Fuel debris
characterizat
ion

Evaluation of
dose
distribution

Material
accountancy,
nondestructive
measurement

Evaluation ofradioactive
fine particles

Corrosion
underpeculiar
environment

Elucidationof aging
degradationof fuel debris

Fuel debris
storage andmanagement
technology

15

Fuel Debris Retrieval R&D

Ensure safety during a series of fuel debris retrieval operation
2030 vision ①a︓the first/trial fuel debris retrieval from Unit 2 is progressed, so that safety / risk
assessment methodologies of a series of fuel debris management operation are establishedKey

Items for analysis
and risk assessment

Radiation exposure, scattering(α dust, FP, gas generation),
criticality, heat generation

Radiation exposure, scattering(α dust, FP, gas generation),
criticality, heat generation＜ Transfer ＞＜Retrieval＞

Key R&D priorities

Criticality, heat generation,
debris amount2030 vision ②: analysis/evaluation methods including
non-detractive assay technologies are establishedp

Estimate PCV internal condition
and fuel debris characterizationp

Examine safety/risk assessment
for fuel debris retrieval operation

p Improve/update analysis
capability and standardization
ü Build/upgrade sample
analysis facilities
ü Develop non-distractive
measurement technologies＜ Interim storage ＞

Okuma Lab-2<Analysis>
16Fuel Debris Retrieval R&D

Ensure safety during a series of fuel debris retrieval operation
2030 vision ①b︓larger-scale fuel debris retrieval from Unit 3 can become ready, as result of
selecting and planning retrieval methods/approaches including access and containment
ü Outcomes of R&D/engineering works
ü Knowledge/expertise

Retrievalmethods
MDA
evaluation

Partial submersion

Submersion
Examine/design
specifications etc.

Challenges/
risks
Identify
issues/risks

A flow of selecting retrieval methods(Source: NDF Technical Strategic Plan 2022)

I Preparatory work

A partial submersion method(Combination of top-entry and side entry accesses)

III Outside
PCV
work
III
OutsidePCV
work

A submersion method(Hull structure design)

Key R&D priorities
IV Transfer/storage

II Internal PCV work

Fuel debris retrieval work flowp

Estimate PCV internal condition
and fuel debris characterizationp

Establish methodologies forsafety/risk assessment for fueldebris retrieval operation
ü Access to internal PCV
ü reducing radiation dose/
exposure

2030 vision ③: safety/risk assessment methods of fuel debris
during the retrieval, transfer and storage are established17

Fuel Debris Retrieval R&D

Estimation of PCV Internal Condition and Fuel Debris Characterization
Fuel debris retrieval(First trial at Unit 2)
Estimate PCV internal
condition and fuel debris

Improve work environmentand reduce dose

Actions/solutions

Fuel debris retrieval(Expansion of scale)Radiological and material
analysis

Backcasting

JAEA R&D focuses/priorities
p Estimation of PCV internal condition

Consolidate data toevaluate safety and risk

■ 2030 vision: ideal state(to be discussed further)
1. The first/trial fuel debris
retrieval from Unit 2
progressed, and larger-scale
retrieval from Unit 3 nearly
ready.

➡ Unit 2➡ Unit 3➡ Unit 1

2. Fuel debris analysis (incl.
non-destructive methods)
becomes well ready➡ Experimental approaches withsimulated debris➡ Uranium-bearing particle analysis

3. Methodologies for safety andrisk management
established

p Fuel debris characterization

18

Estimation of PCV Internal Condition
Unit 2・Most of the fuel debris is sedimented in the lower part of the pressure vessel.
・The fallen fuel debris is metallic and is deposited relatively thinly in the pedestal.
・Molten Core Concrete Interaction (MCCI) has rarely occurred.
【 Understanding the fuel collapse phenomenon 】
・Molten fuel collapses into the cooling water, and oncecooled and solidified
・Many particulate debris (easily oxidized and dispersed,
and easily air cooled)
・Re-melted (1000-1300°C) by decay heat, locallydamaging RPV and falling
Relation between plant conditions resulting from the accident progression and subsequent condition changes.
On platform

PlatformOn
platform

Bottom ofpedestal
Bottom ofpedestal

Molten and solidified
metallic debris blockage(Stone-like accumulates)
Relocated pats of a control
blade and the otherassembly parts
Relocated and solidified
metallic debris(Solidified molten material)

Understanding the formation process and characteristics offuel debris through large scale simulation tests
Unit 2 containment vessel sediments and simulated products

Estimated internal PCV condition
19

Estimation of PCV Internal Condition
Unit 3・Some fuel debris may remain in the lower part of the pressure vessel.
・Fallen fuel debris is sedimented on the pedestal in a complex state due to complicatedsolidification from the solid-liquid state and entrapment of structural materials.
・MCCI has rarely occurred.
【 Understanding the fuel collapse phenomenon 】
・Molten fuel collapses into the cooling water, andonce cooled and solidified
・Many lumpy debris (difficult to oxidize anddisperse, difficult to air cool)・Re-melted (2000-2300°C) by decay heat, and fellover several hours in a highly viscous state
Relation between plant conditions resulting from the accident progression and subsequent condition changes.

Estimated to be under sediment. Observe central
heave and residual structural material.
⇒ Viscous collapses over several hours
Internal investigation result

Estimated internal PCV condition
20

Estimation of PCV Internal Condition
Unit 1・Almost no fuel debris estimated in pressure vessel
・Fallen fuel debris is spread inside and outside the pedestal and sedimented in a complex.
【 Understanding the fuel collapse phenomenon 】
・ Data at the time of the accident is scarce, andadequate evaluation has not progressed.

Relation between plant conditions resulting from the accident progression and subsequent condition changes.

Futurework
Quite different from conventional expectations

Internal investigation result

Estimated internal PCV condition
21

Fuel Debris Characterization

Debris characterization data and knowledge-basePebble
type

Crust
type

Knowledge-base of fuel debris characterization(samples obtained from 1F internal investigation)
・ Collaboration with analytical organization (hot laboratory)
responsible for fuel debris analysis.
・ Discussion by hot lab researchers and engineers withTEPCO HD experts.

Stump
type
MCCI
type

Estimation of core status(Figure of debrisʼ location）

Characteristics list
The knowledge obtained through tests using simulated fueldebris and the development of analysis technology issummarized in a characteristic list with literature.

Sampling
Micro sample(Sediments, smear, etc.）

Characterization of MCCI products by large-scale test

Category

Density

Vickers hardness

Elastic modulus

Fracture
toughness

Thermalconductivity

Specific heat

Melting point

Materials/Phases(g/cm3)

(GPa)

(GPa)

(MPa･m1/2)(W/mK)(J/g･K)

(oC)

10

0.3

2850

0.6

(tr.)

Oxide
UO2

11

6

190

2

ZrO2-T

6

11

200

10

1

!

3

(U,Zr)O2-C

6

SiO2

2

Al-Ca-Si-O

2

Cr2O3

!

11

6

(Zr,U)O2-T

!

3
3

6

!

18

140

!

220

3

1

!

10

0.3

!

0.6

6

!

18

150

!

200

8

1

!

3

0.5

!

0.6

4

!

17

4

!

12

40

!

80

1

22

!

29

100

!

240

1

100

1

1

20

!

110

2

20

11

20

!

110

2

6

4

0

1

30

!

50

1

Zry-2

7

1

!

3

60

!

110

15

α-Zr(O)

7

2

!

11

120

!

210

1

!

10

190

!

200

UO4･4H2O

4

9

8

SUS/FeFe2(Zr,U)

!

7

!

!

Metal

5

10

!

(Zr,U)SO4

UO2 should be oxidised underoxygen existing, and it causes
volume change, makes powders

2850

(tr.)

1.3

1

!

Stability

1710

0.8

1600

1700

1) Characteristic table for micro-Characterisation of debris from microscopic point of view
(Mainly, properties of single-phase material)
!

5

8

Fe3O4

2500

Behaviour at hightemperature

7!

Others
B4C

3

ZrB2

6

Fe2B

7

0.8

33

0.8

0.5

!

!

2400
1597
(d.)

0.8

0.4

(d.)

23

0.3

1850

23

0.3

1580

200

80

0.4

1075

3

80

0.4

1500

450

5

29

2.3

2450

440

10

24

0.7

3040

200

10

24

0.6

1389

3

!

1

5

!

10

There are explosion cases of Zr fine

!

2130

!

1535

2) Characteristic table for macro-Characterization of debris from macroscopic point of view
(Mainly, features of multi-phases material/mixture )
8

7

!

9

24

19

!

16

22

160

!

200

These were summarised & shared as basic information to discuss andevaluate fuel debris characterization and core status.
22

Fuel Debris Characterization
Uranium-bearing particles

Analysis technology and characterization(samples obtained from 1F internal investigation)
Demonstrate a sequence of procedures for unknown particles containing uranium, including sample
collection, transportation, selection of analytical methods, sample pretreatment, analysis, and evaluation.
Preparations for the analysis of fuel debris for the trial retrieval of fuel debris and subsequent expansionof the scale have been reliably advanced. The results will be reflected in the analysis techniques for the
Okuma Lab. 2.
Well plug smear of Unit1○Outer appearance
and dose distribution○Analysis result

(U,
Fe)O2
Fe3
O4

Outer appearance and IP
低⾼SEM/EDX

TEM

FE-SEM/WDX
l Analysis results are integrated into debrisWiki and disclosed as a database.
l Utilized for estimation of knowledge such as chemical properties of fuel debris and estimation of
accident progression scenarios.
l Provide the results to the international community through the OECD/NEA international project andutilize them for joint analysis by participating countries.
強度23

Integration of knowledge and data

Systematic and multilayered compilation of findings
Category

Density

Vickers hardness

Elastic modulus

Fracture
toughness

Thermalconductivity

Specific heat

Melting point

Materials/Phases(g/cm3)

(GPa)

(GPa)

(MPa･m1/2)(W/mK)(J/g･K)

(oC)

10

0.3

2850

0.6

(tr.)

Oxide
UO2

11

6

190

2

ZrO2-T

6

11

200

10

1

!

3

(U,Zr)O2-C

6

!

11

6

(Zr,U)O2-T
SiO2

2

Al-Ca-Si-O

2

!

3

!

3

Cr2O3

5

Fe3O4

5

6

!

18

140

!

220

3

1

!

10

0.3

!

0.6

6

!

18

150

!

200

8

1

!

3

0.5

!

0.6

4

!

17

4

!

12

40

!

80

1

22

!

29

100

!

240

1

20

!

110

2

7

100

1

8

!

11

20

!

110

2

4

0

!

1

30

!

50

1

Zry-2

7

1

!

3

60

!

110

α-Zr(O)

7

2

!

11

120

!

210

SUS/Fe

8

1

!

10

190

!

200

200

!

9

160

!

200

(Zr,U)SO4

4

UO4･4H2O

!

9

1

!

20
6
1

!

0.5
10

1600

!

0.8

2400

0.8

1597

!

UO2 should be oxidised underoxygen existing, and it causes
volume change, makes powders

2850

1710

0.8
33

!

Stability

(tr.)

1.3

1
10

2500

Behaviour at hightemperature

1700

(d.)

0.8

0.4

(d.)

Metal

Fe2(Zr,U)

7

!

8

7

15
3

!

5

23

0.3

23

0.3

1580

!

2130

80

0.4

1075

1850

!

1535

3

80

0.4

1500

450

5

29

2.3

2450

440

10

24

0.7

3040

200

10

24

0.6

1389

There are explosion cases of Zr fine

OthersCharacterization of MCCI products

debrisWiki

B4C

3

ZrB2

6

Fe2B

7

24
19

!

16

22

Characteristics list

Most probable accident scenario
24

Fuel Debris Retrieval R&D

Safety/risk assessment for fuel debris retrieval operation
Fuel debris retrieval(First trial at Unit 2)
Demonstrate equipment
and operator training

Improve work environmentand reduce dose

Backcasting
Actions/solutions

JAEA R&D focuses/priorities
p Safety/risk assessment
methodologies and knowledge➡ Radioactive particles/radiation effect➡ Hydrogen generation➡ Aging management

p Reducing radiation dose/exposure➡ Radiation measurement/visualization➡ Advanced radiation source evaluation

Fuel debris retrieval(Expansion of scale)Radiological and material
analysis

Consolidate data toevaluate safety and risk

■ 2030 vision: ideal state(to be discussed further)
1. The first/trial fuel debris
retrieval from Unit 2
progressed, and larger-scale
retrieval from Unit 3 nearly
ready.
2. Fuel debris analysis (incl.
non-destructive methods)
becomes well ready
3. Methodologies for safety andrisk management
established25

Fuel Debris Retrieval R&D

Safety/risk assessment for fuel debris retrieval operation
Year

〜2022

Main task

Master plan

PCV internal
Investigation

2031〜

Start fueldebris retrieval(Unit 2)Analysis and Estimation

Device design【 Debris handling, processing, and disposal】
Equipment forsafety system, storage
maintenance, etc.
・R&D for fuel debris
retrieval and storage
・ Characterization

・Radioactive effects (H2generation, etc.)
・H2 diffusion /combustion explosion
behavior analysis)
・ Aging of fuel debris
・ Risk control/reduction(H2 recombination
catalysts, etc.)

Conceptual
designFurther expansion offuel debris retrieval scale(Unit 3, Unit 1)

Expand the scaleof retrieval gradually(~kg order)(Total ~880t)(~g order)・Characterization of fueldebrisR&D (Led by JAEA)

2023〜

α-contaminatedwaste by removalof obstacles, etc.

Review of investigation operations flexibly based on new findings

Technology
development

Installation ofstorage equipment(Unit 2, 3)

Installation of
temporary storage
Equipment (unit 2)・Elucidation of aging degradation of fuel debris
・Improvement of safe and efficient process and storage
after retrieval, at conditioning and disposal
Integration of knowledge on characterization of fuel debris
・ Aging degradation, radioactive fine particles including α-dust
Storage and management
・ H2 generation, evaluation method (G value)・ H2 combustion/explosion behavior analysis
code system
・ Suppression / reduction of radiation effectDissolution andmicrobial effects

Establishmentof effective
evaluation
methods forH2 generation

Safety assessment during disposal
・ Risk assessment methods for fire/explosion,
corrosion/degradation, and leakage

Long-term
safe storage

・Sort of debris and waste
・Rationalization of equipment
and facilities
・Long-term storage【JAEAʼS mission】
Provide ofknowledge such as
the confinement ofradioactive particles,
radiation behavior, etc.,
information that
contributes todiscussions on fueldebris treatment anddisposal, andknowledge on risk
assessment methods.
26

Safety/risk assessment: methodologies/knowledge
Radioactive particles/radiation effectEvaluation of spatially dose rate before the start of debris retrieval operation

Unit 1

Feedback

・Accident progression analysis
・Combustion and radioactivation analysis
・Fuel debris characterization
・Muon imaging
・Camera imaging
・Radiation dose measurement

Unit 2・Monte Carlo simulation
・Source sensitivity analysis
・Dose rate analysis
・Developing simulation model・Enhancements/improvement

Unit 3

1st Entry(2012)
A2(2017)
S/C

Well (2021)

A2ʼ
(2018)

3D PCV model (Unit 2)27

Safety/risk assessment: methodologies/knowledge
Hydrogen generation

To assess the risk of H2 explosion after storage of radioactive materials such as fuel debris,
experimental and analytical researches from H2 generation to explosion are conducted.
H2 or H2O2 formation, P [10-8 mol/g]

30salt of seawater added

sample height: 1 cm
air-saturated, R.T., dose rate 2-5 kGy/h (Co-60)[mol/mol] max 1.8% (this case)50  seawater 0.5M NaCl+1mM KBr
seawater salt effect 1mM KBr
outlet40  0.5M NaCl pure water

H2

20

H2

H2O2

10

0
0

residual water

P [mol/g]  G [mol/J]  D [J/g]
2

4

6

0

2

4

6

8

Absorbed dose, D [kGy]

H2 distribution in containers(Calculation)
H2-air premixed flame expansion (Exp+Calc)
H2 generation by water radiolysis (Exp)付与・吸収

energy deposition
to complex system

発⽣・損傷

H2 generation

by water radiolysis

拡散・流動diffusion/
convection

in/among facilities

燃焼・爆発

combustion/
explosionin facilities(1) Radiation research part(2) H2 safety research partH2 flow diagram of generation to explosion

28

Safety/risk assessment: methodologies/knowledge
Aging management＜ Implemented in collaboration with universities＞
Extraction of representative characteristics
based on fuel debris characterization
Arrangement ofEnvironmental conditions
that affect aging

Summary of fuel debris
properties andenvironmental conditions

Elucidation of aging mechanism

Elucidation of aging
process of fuel debris, etc.
Comprehensive
aging prediction
Examination of impact
on decommissioning
work, etc.

Elucidation ofphysical mechanisms

Elucidation ofchemical mechanisms
Elucidation of
biological mechanisms

Examination ofprediction methods＜ Implemented mainly by JAEA ＞

29

Reducing radiation dose/exposure
Radiation measurement/visualization“Visualize” invisible radioactive hotspots in three dimensions Three̶Understanding the distribution of radioactive substances. dimensionallaser scannerComptoncameraRadiation
survey meter

Integrated Radiation
Imaging System (iRIS)
Working route3D map visualizing radiation dose rate*1
Hot spot(Red)

Image of highcontamination

Measuring ofdose rate ateach point◀The resultant image of the hot spots
obtained from the Compton camera isoverlaid on the three-dimensional model
inside the Fukushima Daiichi NPS building
constructed using the photogrammetry
technique.*2
Compact Compton camera▶

*1 Y. Sato and Y. Terasaka, J. Nucl. Sci. Technol. 2022; 59: 677–687. *2 Y. Sato et. al., J. Nucl. Sci. Technol. 2019; 56: 801–808.

30

Reducing radiation dose/exposure
Radiation measurement/visualization
Monitoring and confinement management of alphanuclides are critical during fuel debris retrieval works.

In-situ alpha aerosol monitor (IAAM)

Real-time high-resolution visualizationof individual alpha particle spots

241Am alpha source

EMCCD Camera

β/γ nuclides,

Microscope

20%
Effective doseupon inhalation

α nuclides,
80%

Scintillation light
α particles

Scintillator
Plutonium Particle

Percentage of effective dose upon inhalation, calculated
based on the radioactive inventory of 1F-U2.
31

Reducing radiation dose/exposure
Radiation measurement/visualization

The Optical Fiber Laser-induced breakdown spectroscopy (LIBS) analysis method
LIBS Probe
Basic
Type

Elemental
Analysis

Safe area
Pulse
Laser

Spectroscope

OpticalCouplerHigh dose area

Laser Head

Radiation-proof Fiber

Fiber Camera

LIBS Probe
Edge
PlasmaLaser Light
Emission
Laser-produced plasma

Application to in-situ
analysis in a reactor

Laser Power
SupplySpectroscope

Application to hot cell in-situ analysis

1kSv/hHumid
Environment

100Sv/hDryEnvironment

Using Basic Type32

Reducing radiation dose/exposure
Advanced radiation source evaluation

Radiation source evaluation system by using digitalization technologies
Conceptual image of the system[measurement data]
Air dose rate
Point cloud
Photos etc.

Real field (1F)

Decommissioning
work plan

Database

Inverseestimationof radiation
source(ex. shielding,decontamination)

Interactive visualization
Estimationof dose rate(ex. distribution ofradioactive substances,
air dose rate after thework)

Validity confirmation
using JMTR
Hot spot

Cyberspace(incl. XR tech.)

Measurement

Estimation

Good agreement

Structural model(Pool-canal room)

Optimized
Estimatedradioactive source
measurement
Input
pointsmeasurement
data

Measured and estimateddose rate distribution
33

NARAHA Center for Remote Control Technology
Development (NARREC)
Efficient technology development and training via integration of physical and virtual mockups- Mockup : Highly reliable and replicable testing under specific condition- Virtual : Inexpensive evaluation under a variety of conditions

Full scale mock-up field
Unit 2 PCV mock-up for arm-like equipment
demonstration test and operator training (IRID)

3D Virtual Reality System
Linkable

Simulation of source location

Robot test areas

Mock-up stairs※ Source: METI official HP

Robot Test Pool

Motion capture system
34

Fuel Debris Retrieval R&D
Analysis of Fuel Debris

Fuel debris retrieval(First trial at Unit 2)
Demonstrate equipment
and operator training

Actions/solutions

Improve work environmentand reduce dose

Fuel debris retrieval(Expansion of scale)Radiological andmaterial analysis

Backcasting

JAEA R&D focuses/priorities
p Radiological sample analysis at
JAEA hot-lab in Ibaraki/Fukushima➡ Enhancing capabilities andstandardization➡ Okuma New analysis facility

p Non-destructive assay technologies

Consolidate data toevaluate safety and risk

■ 2030 vision: ideal state(to be discussed further)
1. The first/trial fuel debris
retrieval from Unit 2
progressed, and larger-scale
retrieval from Unit 3 nearly
ready.
2. Fuel debris analysis (incl.
non-destructive methods)
becomes well ready
3. Methodologies for safety andrisk management
established35

Fuel Debris Retrieval R&D
Analysis of Fuel Debris

Master plan

Year

〜2022

2023〜

2031〜

Scale up of PCV/RPVinternal investigations

PCV internal
investigation

Start fueldebris retrieval(Unit 2)(~g order)

Design study ofPreconditioning and storage facility
Expand the scaleof retrieval gradually(~kg order)(Total ~880t)

α-contaminatedwaste by removalof obstacles, etc.

・Analysis method
・Characterization
・Core status

R&D (Led by JAEA)

・Analysis method /Standardization
・1F sample analysis /Core status
evaluation
・Preparation of the
Ibaraki area
analysis system
・Reflect to Okuma
lab.-2・ Validation of method
・ Evaluation of fuel debris

・Analytical quality for regulatory
・Application to step-by-step approachof fuel debris retrieval

Establishment of analysis method
Standardization
OutcomeMain task

Review of investigation operations flexibly based on new findings

Evaluation of dose
distribution
TMI-2 debris analysis
International round robin test

Further expansion offuel debris retrieval scale(Unit 1 or 3)

Temporary storage→Long-term stable storage

・Sort of debris and waste
・Material accountancy
・Long-term storage

Sorting technology
for fuel debris andradioactive materials
Non destructive
assay technology
Accuracy of core status andretrieved fuel debris

Material accountancy（Criticality・SG・Waste management, security)【JAEAʼS mission】
Provide ofknowledge such as
analysis, peripheraltechnologies, andreliable analysis
results necessary for
implementation fromfuel debris removal
to long-term stablestorage.

Utilization of JAEAʼs facilities and human resource development through OJT at these facilities
36

Fuel Debris Retrieval R&D
Analysis of Fuel Debris

Information and analysis items necessary for safety and risk assessment
A Safety / risk assessment through fuel debris removal to storage / management
B Safety / risk assessment in fuel debris processing
・In addition to the items applicable to temporary storage, the same analysis items as
radioactive waste are applied. (Inventory evaluation: 38 Nuclide analysis, etc. ）C Safety / risk assessment of fuel debris remaining in the container
Safety / risk
assessment items

Current status
Fig. Core status(Estimated debris distribution)
Upper structural
material
Shroudpart

RPV Lower headpart

Heat generation, criticality,
scattering of fine particles,leakage of radioactive
substances,(hydrogen generation)

Analytical needs

Control rod partCore residue
Pedestal part
Control rod,
Guide tube partDry well floor
Part・ Surface dose rate, dimensions(particle size), density, hardness
・ Nuclide inventory, composition
・ Chemical form, surface condition
・ Moisture content, organic matter
content, hydrogen
・ FP emission behavior, thermal
characteristics

Estimation
・ Plant information
・ Internal investigation results(Dosimetry, analysis of sediments, etc.)
・ Analysis by calculation codesuch as thermal behavior
・ Analysis of retrieved fuel debris
Analytical facility (Okuma, Ibaraki area)

Analysis /evaluation results

Feedback
37

Fuel Debris Retrieval R&D
Analysis of Fuel Debris

JAEAʼs hot laboratories for radiochemical analysis and human resource developmentxOkuma Radioactive
Material
Analysis
放射性物質分析・研究施設
Administrativeand Research
Bldg.
Facility

Lab.-2

Lab.-1

For fuel debris
analysis

Fukushima

For radioactive
waste analysis

Nuclear Science Research Institute (NSRI)

Lab. No.4

Ibaraki

RFEF

Nuclear Fuel Cycle Engineering Laboratory (NCL)

x
Pu-1

EDF

x
Google m apよりOarai Research and Development Institute (ORDI)

FMF

AGF

38

Fuel Debris Analysis

Enhancing capability and standardization
Technology and system for evaluating the characteristics of fuel debris will be established as an approachfor samples with unknown composition.
The simulated fuel debris prepared by an independent organization will be supplied to the hotlaboratories in Japan.
The elemental composition will be analyzed using their own technology possessed by each laboratories.
Hotlaboratories
Simulated fuel debris(uniform composition)
・Including U
・1F composition

TohokuUniversity

NDC

JAEA Oarai

NFD

JAEA NSRI

Dissolution
methodDissolution
rate

HNO3

〜60%

HNO3
+ HF

〜90%

Aqua regia
+HF

98%

Alkalifusion100%

Remarks
・Simple method
・Dissolves U and B compounds
・Complement the overall elemental
composition by analyzing residue
・Improved dissolution rateby adding a small amount of HF

Conducted by remotecontrol within the cell・Almost complete dissolution
・High accuracy
・Possibility of fluoride precipitation
・Complete dissolution
・High accuracy
・Contamination of alkaline reagent
Verification of accuracy andand crucible components
error for each analysis target
element and operation

Analysis techniques for 4 basic evaluation items (morphology of analysis samples, nuclide/element
content, phase state/distribution, density, etc.), which are important for fuel debris analysis items,
are defined and shared among the parties concerned.
https://dccc-program.jp/files/202108jaea.pdf

39Fuel Debris Analysis

Non-destructive analysis technologies
Non-destructive assay technology for sorting of fuel debris and radioactive wasteü Destructive analysis of recovered PCV materials up to the order of kilograms stored is difficult.
ü In order to reflect the sorting of fuel debris and radioactive waste in the future, non-destructive
assay technology will be developed to sort them according to the amount of nuclear fuel material.
Candidate methods currently under consideration in the IRID project:(Participating organizations in the project: MHI, Toshiba ESS, Hitachi GE, JAEA collaboration)(1) Active neutron method, (2) Passive neutron method, (3) Muon scattering method,(4) X-ray CT method, (5) Passive gamma ray method

Smallpulsedneutrongenerator

ChamberCd

He-3proportional counter
polyethylene

Active neutron method (JAWAS-T)
NSRI/NUCEF/BECKY

Passive neutron method (PSMC)
NCL/Pu-center

Considered for use in passive gamma-ray
measurement, etc.
NSRI/RFEF

Overview of basic test equipment for non-destructive assay measurement methods(JAEA facilities and equipment scheduled to be implemented from 2023)
40

4. Radioactive waste management R&D

41

41

Radioactive waste characterization and analysis
Current status of waste storagen Temporary storage of solid waste on site of Fukushima Daiichi* NDF, “Technical Strategic Plan 2021,” Fig. A10-1, October 29, 2021.

42

Radioactive waste management R&D

Actions/solutions

Backcastingn JAEA R&D focuses/priorities■ 2030 vision: ideal state(to be discussed further)
1. A risk level of remaining
high-risk radioactive wasteconsiderably reduced

p Risk reduction of secondary wastefrom water decontamination➡ Radiochemical and other analysis➡ Investigating mechanism for storage

2. Rational characterization
methodologies established(e.g. statistical methods)

p Waste characterization anddevelopment of statistical methods➡ Continuing analysis➡ Developing analysis method,planning, statistics, database

3. Discussion on a variety ofoptions for waste disposal
can be started！
p Safety of waste processing/disposal➡ Basic data for processing anddisposal
43Radioactive waste management R&D

Risk reduction of secondary waste from water decontaminationn Safe storage of relatively high-risk waste:secondary waste from contaminated water processing
Table: Risk categories and sources

︕* NDF, “Technical Strategic Plan 2021,” Fig. A10-1, October 29, 2021.

Relatively high risks
given high priority

Fuels in SFPs

Immediate risk unlikely,
but risk may grow whenhandling with haste

Fuel debris

Increased risk unlikely inthe future, but
appropriate
decommissioning efforts
are required

ALPS slurry, waste sludge,
concentrated liquid waste,zeolite sandbags,
outdoor storage

Sufficiently stable
management

Fuels in common pool,
Sorption vessels, Fuels in
dry casks, Rubble instorage facility, Stored
water in welded tanks,
Soil covered temporarystorage(Note) Waste in red was already radiochemically analyzed.
44

Radioactive waste management R&D

Risk reduction of secondary waste from water decontaminationn Extensive analysis of contaminated water treatment sludge

Interface

Sludge stored at “D pit”*

P3

P1
P1

Sedimentation behavior of sludge
observed in hot cell due to its highβ activity

P2
P2

wt%

P3

The only sample
successfullycollected

Distribution profile

60
55
50
45
40
35
30
25
20
15
10
5
0

面分析
点分析 P1
点分析 P3
点分析 P2
点分析 P4O Na Mg Al Si S Cl K Ca Ba Fe Ni Zn

Elemental concentration

10μm

Visual observation of sludge particle

P4
SEM image and points of elemental
analysis!中心$点分析(実施

P4* TEPCO, “Report on stabilization of slurry and sludge,” 25 July 2017.

45

Radioactive waste management R&D

Risk reduction of secondary waste from water decontaminationn Study on storage methods: evaluate radiation effect during longterm storage
給水管

Before irradiation

44 hours

22 hours

6 hours later

ベント管
排水管

ヒータ

給水管

ベント管
排水管

容器高さ
265cm

Supernatant

内径89cmヒータ
ゼオライト

Initial interface

Expansion of solid phase due to generation ofhydrogen, observed in simulating experimentusing 60Co source

Experimental setup to investigate water evaporation
behavior(K)

Mg/Ca ratio(mol/mol)

MAX temp.
in zeolite
bed!153℃

MAX H2concentration!
1.29%"under the lower
explosive limit#

Yield stressSlurry A

B

C

D

E

Synthesizing simulated sludge to investigate
physical property of solid phase(a) Temperature(b) Molar fraction of H2

Calculation of hydrogen concentration to confirm
safety of explosion
46

Radioactive waste management R&D

Waste characterization and development of statistical methodsn Analysis of radioactive waste: information/data required for risk
assessment
Items for analysis and risk assessment

Confinement, stability, environmental effectDose, criticality, fire/explosion

Generation

First
classification

Temporarystorage

Dose, stability

Volume reduction,
stabilization
Secondclassification

StorageThirdclassification

Conditioning

Disposal

Needs for analysis
Characterizing for storage

Characterization for processing(conditioning)

Characterization for processing(stabilization)

Characterization for disposal

Characterization for decomposition

ü Unique feature of waste originating from the
Fukushima Daiichi accident• Difficult to predict radioactivity composition
including DTM “Difficult-To-Measure” nuclides• Enormous amount• High dose rate(including conditioning)•••

Inventory estimation method
Analysis planning method
Analysis method for DTMs

47

Radioactive waste management R&D

Waste characterization and development of statistical methods

n Characterizing radioactive waste: analysis and related items fordeveloping waste processing/disposal technologies

Sampling

Radiochemical analysis

Developing analysis procedureWeb-based database

Estimated radioactivity contained in waste

Flow of characterization, composite of various items

Important items of characterizing waste
48

Radioactive waste management R&D

Waste characterization and development of statistical methods

49

Radioactive waste management R&D

Waste characterization and development of statistical methodsn Analysis planning is enforced by integrating international expertise

Data Quality Objectives (DQO) Process,originally developed by US EPA

Calculating effective number of samples using
Bayesian statistics as a result of UK collaboration
50

Radioactive waste processing and disposal
Safety of waste processing/disposaln Preparing technology selection for solidification/disposal concept
Examples of basic data related to waste processing

Cementitious solidification criteria for carbonate slurry

G-Value (H2/100eV)

0.4

OPC+IS
M+IS
MB20+IS
MB40+IS

0.3

OPC
M
MB20
MB40

Cl effect

0.2

0.1

0.0
0

Example of basic data on disposal; Distribution
coefficient of iodine for cementitious material
5

10

15

20

25

30

35

Cumulative dose (kGy)

Hydrogen generation “G-value” from iron slurry51

Radioactive waste processing and disposal
Knowledge-basen A database, “FRAnDLi” is widely available for researchers
involved in radioactive waste and decommissioning R&D

https://frandli-db.jaea.go.jp/FRAnDLi/

Example of contents; plot and tables (with CSV download)
52

Radioactive waste processing and disposal
Knowledge-basen Analysis data and related methodologies will be integrated toknowledge base for sustainable decommissioning activities
Methodologies

Analysis planning
Long-term planning
Analysis methods/
Standardization

Database

Analysis of waste samples
A) Distribution of concentrationand nuclide composition
B) Applicability of scaling factor

Inventory estimation• To quantitatively evaluate
uncertainty.

Inventory verification• Considering waste populationand their nuclide composition.

Analytical data
• FRAnDLi shall be operated.

C) Waste population

Analysis samples• To be developed for effective
use of data obtained.

D) Inventory verification
methodDecision making• To determine waste group(population) and their inventory
verification method, which
conform to waste packaging
and disposal.

Quality assurance• To prepare for future useof data with reliability.

53

Radioactive waste processing and disposal
Okuma Analysis and Research Center
Okuma Analysis and Research Center
Laboratory-2

Laboratory-1
Administrativebuilding

Lab-2 (Pre-construction phase)

Laboratory -1• Hot-cell operation has started in October 2022.
• Analysis of low-and-medium-dose radioactive wastes.
• Analysis of ALPS-treated water as third-party institution.

Iron cells

Glove boxes

Fume hoods• Construction will start soon after the licensing
process to be cleared.
• Analysis of high dose samples such as fuel debris.

Concrete cells※The image shows a concrete
cells at another JAEA site.

54

Disposal of ALPS-treated water(Source) TEPCO website, https://www.tepco.co.jp/en/decommission/progress/watertreatment/oceanrelease/index-e.html
55

Disposal of ALPS-treated water

Third-party analysis at JAEA Okuma Research and Analysis Centern Waste sample is pretreated in Iron Cell Room/GB Room/Fume Hood Rooms depending on
surface dose rate. ALPS treated water sample is pretreated in Fume Hood Rooms.
n Sample flows are separated to prevent cross contamination.
3F/2F

2F

Flow of ALPS treated water sample（, separated from waste sample
to prevent cross contamination ）4 Cells
Iron Cell Room

Pretreatment (cutting)Lording Dock

〔Analysis〕

10 boxes
56 hoods※
Grove Box
〔フード室〕〔グローブ〔フード室〕
Fume
Hood Room(GB)
ボックス室〕
Room

Pretreatment (crushing)

Middle level
doze rate sample(1mSv/h〜1Sv/h)

Air Lock
Room

Pretreatment(dissolution, separation and preparation)

Panel House Room
Low level
dose rate
sample(≦ 1mSv/h)

1F〔測定室〕 Room (part of theAnalysisanalysis is performed in 2F area)〕

Flow of waste sample〔⼩型受⼊物
Small
※1〕
待機室
SampleStorage

Pretreatment (cutting)※ : The number is including hoods which used for pretreatment, liquid waste
treatment and radiation management.

56

Disposal of ALPS-treated water

Third-party analysis at JAEA Okuma Research and Analysis Center
Preparation is ongoing for reliable analysis with proper measurement methods foreach nuclides
3 Steps for Analysis①Pretreatment②Measurement③Evaluation① Pretreatment
Sample is made finer, dissolved ina liquid, or separated according toproperties, etc.

② Measurement
Pretreated sample is set into
various measuring equipment.
Acquired data is processed by
calculation if needed.

Measurement of tritium
concentration in ALPS
treated water

Confirmation that the concentration ofradioactive substances other than tritium
is below the regulatory standard（Cs-137, Sr-90, Tc-99, etc）

【Pretreatment】
Removing impurities thatinterfere with measurement
by distillation【Pretreatment】
Adjusting the target nuclide to the state
suitable for the measurement by
operation such as separation

Fume Hood【Measurement】
Measuring β radiation fromtritium by liquid scintillation
counter (LSC)

Ex. Separatingtarget nuclides by
operation such as
solid-phaseextraction thatabsorbs specificsubstance to resin

Fume Hood【Measurement】
Measuring nuclides by equipment
suitable for each nuclide
Ex.Cs-137:Ge semiconductor detector
Tc-99 :ICP-MS③ Evaluation
Result is compared with standard
value for judgement/check of data
trends.

Example of LSC

Ge semiconductor detector

ICP-MS57

5. Contribution to Fukushima reconstruction

引用：METIホームページ

58

Contribution to Fukushima reconstruction

Collaboration with the new Fukushima research institute (F-REI)
A pilot study of Fukushima Institute for Research, Education and Innovation (F-REI):
Long-term tracing research of Fukushima ecosystem (Long-term ecological research: LTER)l Long-term ecological research with the use of radioactive materials released by the 1F accident
and stable isotopes in the Fukushima ecosystem as environmental tracers
l Field study for a long-term ecological research in a watershed scale with a few 10 km square(installation of study field of long-term ecological research)l Assessment of impact of human activities on the biogeochemical cycle and biologicalcommunity in the study field of long-term ecological research
Fallout ofradioactive
materials
Nuclearpower plant
accident

Semi-naturalenvironment

ü Return of residents<Evacuation>
ü Restart of human activities<Decontamination>1) Non-maintained seminatural environment(plantation, Satoyama)(plantation, Satoyama)

2) Maintained
semi-naturalenvironment(Satoyama)

Weather event
Human impact“Analogue study on the impact of human activities on asemi-natural environment”

A schematic
diagram of study
field

Impact of humanactivities on theenvironment

Situation after event A
Situation after event B
Situation after event C
Situation after event N

All research data is stored in the Data
catalogue developed in this research

59

Contribution to Fukushima reconstruction
Collaboration with local stakeholders
Working with local industry partners
Signal processing board
Optical camera

Drone

γ-ray sensor

Compton camera
Display

LiDAR sensor

High dose
rate area

Unmanned ship

Radiation monitoring drone
with visualization*1

SensorUnmanned ship for monitoring and sampling

Sensor for polluted water leakage

Education and training for young generation

Training courses for high-school

Creative Robot Contest for Decommissioning60*1 Y. Sato et. al., J Nucl. Sci. Technol. 2020; 57: 734–744. This system was developed jointly with Chiyoda Technol Corp..

Contribution to Fukushima reconstruction
Collaboration with local stakeholders
Local events

Annual conference in Fukushima▲ Nara-SUN-Fes 2021 exhibition ▲NARREC▲ Panel session

CLADS▲ Presentation by JAEA staff
Poster session ▶

▲ Open house ▲Fukushima Research Conference (FRC)
Future conferences
Workshop on Mission H :l Matching needs and solutionsl Promotion for Japan-UK joint research
programl FY2022 debriefing meeting▲ FRC participants▲ Workshop
61

Working together for the future of Fukushima!
International Topical Workshop on
Fukushima Decommissioning Research

JAEA’s platform for
fundamental research on decommissioning

Thank you very much for your attention.
62