Technical Strategic Plan 2022 for Decommissioning of
the Fukushima Daiichi Nuclear Power Station of Tokyo
Electric Power Company Holdings, Inc.

Overview

October 11, 2022

Nuclear Damage Compensation andDecommissioning Facilitation Corporation

Table of Contents
1. Introduction .................................................................................................................................. 3
2. Concept for reducing risks and ensuring safety in the decommissioning of the Fukushima
Daiichi NPS.................................................................................................................................. 6
3. Technological strategies toward decommissioning of the Fukushima Daiichi NPS .................. 20
3.1 Fuel debris retrieval .............................................................................................................. 20
3.2 Waste management.............................................................................................................. 54
3.3 Contaminated and treated water management .................................................................... 63
3.4 Fuel removal from spent fuel pools ...................................................................................... 74
4. Analysis strategy for promoting decommissioning..................................................................... 78
5. Efforts to facilitate research and development ........................................................................... 84
6. Activities to support our technical strategy................................................................................. 90
6.1 Further strengthening of project management and improvement of capability required as adecommissioning executor .................................................................................................. 90
6.2 Strengthening international cooperation .............................................................................. 96
6.3 Local community engagement.............................................................................................. 99

2

1. Introduction
The long-term approach to the decommissioning of the Fukushima Daiichi Nuclear Power Stationof Tokyo Electric Power Company Holdings, Inc. (hereinafter referred to as the "Fukushima Daiichi
NPS") has proceeded under “the Mid-and-Long-term Roadmap towards the Decommissioning ofFukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company Holdings, Inc.”(hereinafter referred to as “Mid-and-Long-term Roadmap”), developed by the Japanese
Government.
In March 2022, the earthquake occurred with its seismic center off the coast of Fukushima
Prefecture, measured a lower 6 on the Japanese seismic intensity scale of 7. However, there wasno leakage of radioactive materials into the environment and no significant impact on the plant
operations. The Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Company
Holdings, Inc. (hereinafter referred to as “TEPCO”) is avoiding any effect on safety assurance
caused by personnel shortages by taking thorough infection prevention measures against newcoronavirus infections, which have been ongoing since FY2020. Nonetheless, the effects of global
action restrictions and semiconductor shortages are unavoidable, and efforts are being made tominimize these effects. Under these circumstances, the decommissioning of the Fukushima Daiichi
NPS is being prepared for the trial retrieval of fuel debris (internal investigation and fuel debris
sampling) in Unit 2. Theis trial retrieval (internal investigation and fuel debris sampling) is the final
stage of Phase 2 as indicated in the Mid-and-Long-term Roadmap and will be the basic form of onsite configuration for the future fuel debris retrieval work. Therefore, this phase requires more
careful and cautious preparation. After transited to Phase 3-[1], preparations for full-scale debris
retrieval and efforts to complete fuel removal from the spent fuel pools in all units will be promoted.
Nuclear Damage Compensation and Decommissioning Facilitation Corporation (hereinafterreferred to as "NDF") has supported efforts related to the decommissioning of the Fukushima
Daiichi NPS as an organization that conducts research and development, as well as provides
advice and guidance, required for decommissioning since 2014. This "Technical Strategic Plan for
Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station" (hereinafter referred toas the "Technical Strategic Plan"), as a part of these supports, has been compiled annually since2015, with the objectives of providing a solid technical basis for the Mid-and-Long-term Roadmap
and contributing to its smooth and steady implementation, consideration of revisions, andachievement of the goals of the Nuclear Regulation Authority (NRA)'s "Measures for Mid-term Risk
Reduction at TEPCO’s Fukushima Daiichi NPS (hereinafter referred to as “Target Map for Reducing
Medium-term Risks”)", as well as providing a basis for “The Policy for Preparation of Withdrawal
Plan for Reserve Fund for Decommissioning” (hereinafter referred to as “the Policy for Preparationof Withdrawal Plan”).

31.1 Structures and systems toward the decommissioning of the Fukushima
Daiichi Nuclear Power Station
The division of roles among the organizations directly involved in the decommissioning of the
Fukushima Daiichi NPS, including the Japanese government, NDF and TEPCO, as well asorganizations specializing in R&D, such as the International Research Institute for Nuclear
Decommissioning [IRID] and the Japan Atomic Energy Agency [JAEA], is shown in Fig 1, which
also indicates how the abovementioned systems are implemented.
Based on this division of roles, TEPCO has been working to build and strengthen the project
management structure, and is in the process of making it more effective by enhancing andupgrading the management methods, in order to make systematic and steady progress inaddressing each issue with a view to the mid-to-long-term decommissioning work. From thefinancial perspective, NDF has been carrying out the management of a reserve fund fordecommissioning to ensure immediate decommissioning work. Under this management task, NDF
is to (1) manage the fund for decommissioning appropriately, (2) manage the implementation
structure for proper decommissioning, and (3) steadily manage the decommissioning work basedon the Reserve Fund for Decommissioning, and NDF is assigned roles and responsibilities as anorganization to manage and oversee TEPCO's decommissioning activities. NDF prepared "ThePolicy for Preparation of Withdrawal Plan ", which was drawn up based on the "Technical StrategicPlan", and presented to TEPCO the work goals and main activities to be incorporated in theWithdrawal Plan for reserve fund for decommissioning, and evaluated the appropriateness of
TEPCO's efforts in the process of jointly preparing the Withdrawal Plan for reserve fund fordecommissioning from the perspective of symbiosis and communication with the community, etc.
(Fig. 2).
Nuclear Emergency Response Headquarters (Director: Prime Minister)
Nuclear Regulation Authority➢ Decide the direction of decommissioning and contaminated water
treatment➢ Approval of implementation plan,
pre-service inspection, welding
inspection, etc.
➢ Providing goals for risk reduction(Chairperson: Chief Cabinet Secretary)

Mid-and-Long-Term Roadmap

The Team for Countermeasures for Decommissioning
and Contaminated Water Treatment(Head of Team: Minister of Economy, Trade and Industry)➢ Progress management of each countermeasure according toMid-and-Long-Term Roadmap

Apply forapproval

Nuclear Damage Compensation and Decommissioning Facilitation Corporation➢ Development of a mid-to-long-term strategy

Withdrawal plan

Technical ➢ Tech. support for progress management of important
issues (in collaboration)
Strategic ➢ R&D planning and progress management
plan ➢ Strengthen international partnership➢ Management of Reserve Fund for
Decommissioning

International Research Institute for
Nuclear Decommissioning (IRID)*2
Share progress
Japan Atomic Energy Agency (JAEA), and challengesetc.
➢ R&D implementation
ReportReserve Fund for
Decommissioning

Advice, guidance, recommendations,supervision and support
Reserverelated to project management, etc.

Disburse-ment

Apply for report

R&D organization

Approve

Monitoring, examination

Progressmanagement

Granting of
project budget

Target map for Reducing
Medium-term Risk

Minister of Economy, Trade and Industry
Presentation ofimportant issues

ReportReport on theoutcomeReportBidirectional dialogue

Local residents and communities

Organizations related to decommissioning

Council for the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station*1

Tokyo Electric Power Company Holdings, Inc. (Fukushima Daiichi Decontamination and Decommissioning Engineering Company)➢ Contaminated water and ALPS-treated water management, fuel removal from SFP, fuel debris retrieval, waste management, etc.
➢ Through TEPCO's management reform, the funds required for decommissioning should be reserved
responsibly (Implementation of the 4th special business plan)Mid-and-Long-term➢ Detailed measures for facility safety and protection of nuclear fuel material
Decommissioning Action Plan
(Development of implementation plan for specified nuclear facility)*1 In response to the ALPS-treated water disposal policy decided on April 13, 2021, “Council for the Decommissioning of TTEPCO’s Fukushima Daiichi NPS toward steady implementation of basic policy on ALPS-treatedwater disposal” was founded.
*2 TEPCO, a decommissioning project operator, participates as a member of IRID and shares the needs, challenges, and results of research and development.

Fig.1 Division of roles of related organizations responsible for decommissioning of the Fukushima
Daiichi NPS

4Government* Continually revised based on the progress of programs,
in the past revised once a couple of years

Mid-and-Long-Term Roadmap*
Proposals for Revise

Mid-and Long-term R&D Plan, Next R&D Plan
(The Government-led R&D program on
Decommissioning and Contaminated Water Management)

NDF

Strategic Plan (annual)
The Policy for Preparation ofWithdrawal Plan for Reserve Fund for
Decommissioning (annual)

Feedback

TEPCO

Withdrawal Plan for Reserve Fundfor Decommissioning (annual)

Planning from
Mid-and-long-term aspect

Jointly created with NDF and approved by METI
• Contaminated water management PG• Spent Fuel removal PG• Fuel debris retrieval PG• Waste management PG• General management of the site PG• ALPS-treated water management PG• Facility maintenance/Operational Management

Mid-and-Long-term
Decommissioning Action Plan(annual)On-site work

Engineering

Feedback

R&D

Promotion of Decommissioning project

Fig. 2 Positioning of the Technical Strategic Plan based on the Reserve Fund

1.2 The Technical Strategic Plan 2022
The Technical Strategic Plan 2022 features the status of efforts toward trial retrieval from Unit 2(internal investigation and fuel debris sampling), the status of the examination of methods towardfurther expansion of fuel debris retrieval in scale, the status of efforts toward the discharge of ALPStreated water into the ocean, and analytical strategies for promoting decommissioning.

52. Concept for reducing risks and ensuring safety
decommissioning of the Fukushima Daiichi NPS

in

the

2.1 Basic policy for the decommissioning of the Fukushima Daiichi NPS
The basic policy for the decommissioning of the Fukushima Daiichi NPS is "to continuously andquickly reduce the risks arising from the radioactive materials caused by the accident that do notexist in normal nuclear power plants" by taking measures specifically designed to reduce risks.
In proceeding with decommissioning, it is important for ensuring the safety of decommissioning
operations to consider flexible risk reduction strategies that require a long-term and overall
perspectives on the balance of risks based on the safety features.
2.1.1 Risks management to be addressed in Phase 3-[1]In Phase 3-[1], several processes for risk reduction will be carried out in parallel according to themilestones in the Mid-and-Long-term Roadmap.
• Aim to complete fuel removal from the spent fuel pools of Units 1 - 6.
• Undertake trial retrieval of fuel debris and promote a gradual expansion of the scale of retrieval.
• Minimize and stably maintain the amount of contaminated water generated.
• Eliminate the temporary storage of rubble etc., as a waste management measure.
Regarding fuel debris retrieval, preparation of methods for further expansion of fuel debris
retrieval in scale, which will be full-scale decommissioning work, will be promoted. Even thoughmore than about eleven years have passed since the declaration of the cold shutdown state andthe current state of temperature and pressure inside the primary containment vessel (hereinafterreferred to as "PCV”) is stable, conditions may change with the start of fuel debris retrieval. As theretrieval progresses, the risks attributable to fuel debris will decrease. However, it is undeniable
that risks that were previously perceived as small may become relatively large or that unknown
risks may become apparent. To effectively respond to risks toward further expansion of fuel debris
retrieval in scale, it is necessary to improve the ability to observe conditions inside the PCVs wherechanges in these risks are likely to occur. Therefore, despite the high degree of difficulty,
consideration should be given to expanding the type and number of monitoring targets, while taking
into account the current purpose of the monitoring parameters and the number of monitoring
devices in the PCVs and difficulties in on-site operation. For example, the dust concentration in the
PCVs is expected to increase with fuel debris retrieval work in the case of further expansion of fueldebris retrieval in scale. If the dust concentration in the PCVs can be measured in a phase of
preceding trial retrieval and gradual expansion of the retrieval scale, and the correlation between
the location and scale of the retrieval operations and the dust concentration can be determined, it
is possible to reduce the uncertainty associated with retrieval operations and improve work
efficiency while maintaining an appropriate safety margin.

6

Once the condition inside the PCVs can be observed from a more multifaceted perspective, it isexpected to provide a basis for whether or not the facilities being considered are required for further
expansion of fuel debris retrieval in scale, contributing to the optimization of resources.
In addition to promoting the design, manufacture, and installation of systems related to theretrieval methods, it is also important to secure and train operators and maintenance personnel,
develop a management framework, and establish a rational analysis framework for retrieved fueldebris.
2.1.1.1 Risk reduction
2.1.1.1.1 Further measures to reduce the migration of radioactive materials from PCVs
• Gaseous and dusty radioactive materials
Toward fuel debris retrieval, containment ability should be further enhanced by reducing the
migration of gaseous and dusty radioactive materials that are prone to migration from PCVs.
Specifically, the effectiveness of the reduction in the amount of dust transferred outside the PCV
should be observed by PCV pressure equalization (slightly negative pressure) and an enhanced
dust concentration monitoring function in the PCVs, as shown in 2.1.1.
• Liquid radioactive materials
The migration of liquid radioactive materials, which are almost as easily migrated as gaseousand dusty radioactive materials, should be controlled without fail. Specifically, drainage of the waterretained in the suppression chamber (hereinafter referred to as “S/C”) and other systems thatTEPCO is currently undertaking should be accelerated to minimize the amount of PCV water.

In proceeding with the above, the tests available with the current system configuration, such asreactor water injection shutdown tests and nitrogen supply reduction tests, should be actively
performed in accordance with the “concept of preliminary implementation and utilization of theobtained information in the latter stages” described in 2.3.2, to assess the feasibility, and determine
areas and difficulty of the issue.
2.1.1.1.2 Preparation for long-term risks to the integrity of reactor pressure vessels (RPVs),
primary containment vessels (PCVs), and reactor buildings containing fuel debris
The reactor pressure vessels (hereinafter referred to as "RPVs") and the PCVs were directly
affected by the accident. It has been found that the molten fuel damaged the bottom of the RPVs
and the PCVs were partially damaged by overheating and overpressure.
At the PCV bottom, it is assumed that effects due to contact with the molten core materials andtheir heat occurred. For this reason, prudent approaches should be taken to maintain the long-term
integrity, including the containment performance of RPVs and PCVs and the strength of reactor
buildings, against threats of corrosion of metal materials, deterioration of containment performance,and degradation in strength of the affected concrete structural materials.

7

To achieve that, it is necessary to verify the damage condition inside the PCVs in a focusedmanner and proceed with an integrity assessment based on the latest information on the PCVinterior, assuming long-term risks that may occur in the future, such as earthquakes and aging
degradation. Given the limited information on damage conditions, this evaluation always involves
uncertainty. Still, it is necessary to make diligent efforts to update the evaluation data andincorporate the latest in-core information for reducing uncertainty. Details of initiatives are shownin 3.1.2.6.1.5.
2.1.1.2 Requirement for the further expansion of fuel debris retrieval in scale
The following is required to conduct safe and reliable fuel debris retrieval toward the phase offurther expansion of fuel debris retrieval in scale:Ensure that trial retrieval will be carried out while obtaining knowledge so that it can be utilized
in subsequent gradual expansion of fuel debris retrieval and further expansion of fuel debris
retrieval in scale.

Proceed with designing, manufacturing, and installing systems related to retrieval methods.



It is necessary to establish a system for securing, training and managing operators andcomplete necessary training.



Since preliminary work for retrieval requires operations in the high-dose reactor building, due
to the prolonged work it is important to improve the on-site environment and ensure exposure
control and the long-term availability of workers.

In preparation for hardware, it is necessary to complete environmental improvements in thesurrounding area, such as dismantling and removing exhaust stacks and radioactive waste
disposal buildings.

Moreover, the organizations concerned need to discuss and develop an analysis plan, facilities
for analysis, and an analysis framework for analyzing the retrieved fuel debris rationally.



It is important to facilitate waste storage that does not hinder the above operations.

Specific initiatives for the above are discussed in Chapters 3 and 4.

2.2 Concept of reducing risks caused by radioactive materials
2.2.1 Quantitative identification of risks
The Technical Strategic Plan uses a method based on the Safety and Environmental Detrimentscore (hereinafter referred to as "SED") developed by the Nuclear Decommissioning Authority(hereinafter referred to as "NDA") to express the magnitude of risk (risk level) for radioactive
materials. In this method, risk level can be expressed by the product of "Hazard Potential", which
is an index of the impact of internal exposure in the event of human intake of radioactive material,and "Safety Management", which is an index of the likelihood that an event will occur.

8

The major risk sources of the Fukushima Daiichi NPS are summarized in Table 1. The current
risk levels assigned to these respective risk sources are expressed in Fig. 3 with "Hazard Potential"and "Safety Management" as the axes.
As events that were not anticipated have occurred during the long period of thedecommissioning work, it is important to identify unexpected risks. Although it is not easy to identify
such risks, when an unexpected event occurs, analyzing the event to clarify causes that had notbeen anticipated before provides a clue for risk identification.
At the event of total-β contamination leakage in the rubble temporary storage area reported on
March 25, 2021, leakage of radioactive materials occurred from a container whose contents were
not identified. It has so far been assumed that solid content such as rubble would not immediatelytransfer radioactive materials to the environment due to container damage. However, subsequent
analysis suggested that corrosion of the inner surface of the container caused leakage. In light ofthis event, however, it is important for risk identification to understand physicochemical state andits changes over time, in addition to the location of the risk sources and radioactivity. At the time ofthe earthquake on February 13, 2021, with its epicenter off the coast of Fukushima Prefecture,
lowering of the PCV water levels at Units 1 and 3, and sliding of tanks on site exceeding the sliding
amount evaluated at the time of tank installation were observed. At the time of the earthquake on
March 16, 2022, with its epicenter off the coast of Fukushima Prefecture, a lowering of the PCV
water levels at Units 1 and 3 was observed and the over-turning of containers in the temporarystorage area was confirmed. For the PCVs for which the current state is not well-understood,
understanding the damage condition by internal investigation and assessment of the situation at
the accident, and estimation of aging by monitoring/evaluation are useful for risk identification.
Regarding external events such as natural disasters, it is necessary to thoroughly evaluate inadvance the consequences of and the necessity of countermeasures against beyond-design-basis
events in existing/new systems.
Although none of the above events resulted in significant consequences, it is important tocarefully analyze the events using methods such as root cause analyses, and to identify risks that
had not been anticipated to in order help prevent the occurrence of significant consequences. For
this purpose, TEPCO needs to make efforts to learn from the unexpected events as describedabove.

9

Table 1 Major risk sources at the Fukushima Daiichi NPS
Fuel debris
Spent fuelContaminatedwater, etc.

Fuel in SFPs
Fuel in the Common
Spent Fuel Storage Pool
Fuel in dry casks

Fuel debris in RPVs/PCVs in Units 1 to 3
Fuel assemblies stored in the spent fuel pools (SFPs) in Units 1 and 2
Fuel assemblies stored in the Common Spent Fuel Storage Pool
Fuel assemblies stored in dry casks

Stagnant water in

Contaminated water accumulated in the reactor buildings of Units 1 tobuildings

3, process main building and high-temperature incinerator building,and sludge containing α-nuclides at the bottom of buildings of Units 1
to 3

Zeolite sandbags

Zeolite, etc. in sandbags placed on the basement floors of the process
main building and high-temperature incinerator building

Secondarywaste
generated bywater
treatment

Stored water in welded

Strontium-treated water and ALPS-treated water, etc. (ALPS-treatedtanks

water and water under treatment) stored in welded tanks

Residual water inConcentrated saltwater and sludge containing α-nuclides left at theflanged tanks

bottom of flanged tanks

Waste sorption vessels,

Spent sorption vessels, etc. generated from various contaminatedetc.

water treatment systems such as a cesium sorption apparatus

ALPS slurry

Slurry and waste absorbents generated during treatment by the multinuclide removal equipment and added multi-nuclide removal
equipment, and stored in high integrity containers (HIC)

ALPS slurry

ALPS slurry stored in HICs whose accumulated absorbed doses(to be transferred to

exceeded the criterion value of 5,000kGy (accumulated absorbed

other HICs)

dose with confirmed HIC’s structural integrity against drop) or
evaluated to be close to the criterion value among the HICs affectedby beta irradiation, which are planned to be transferred to other HICs
by the end of FY2023.

Sludge generated at the

Flocculated

sludgedecontamination device

decontamination system

Concentrated waste

Concentrated waste liquid generated by evaporative concentration ofliquid, etc.

concentrated

salt

generated

water

with

duringfurthertheoperation

volumeofreduction

thebyconcentration, and carbonate slurry collected from the concentrated
Rubble, etc.

Solid waste storage
facility
Soil-covered temporarystorage, etc.
Outdoor storage, etc.

Contaminated structures, etc., in thebuildings

waste liquid
Rubble (30 mSv/h and above) stored in the solid waste storage facility
Rubble stored in the soil-covered temporary storage facility andcontainers (1-30 mSv/h), felled trees stored in the temporary storage
pool
Rubble stored in outdoor sheet-covered storage (0.1-1 mSv/h), rubble
stored in outdoor storage (below 0.1 mSv/h), felled trees stored in
outdoor storage
Structures, pipes, components, and other items (shield plugs, standby
gas treatment system pipes, etc.) inside the reactor buildings andPCVs/RPVs that are contaminated with radioactive materials
dispersed due to the accident; and activated materials generated fromoperation before the accident

10Hazard Potential (logarithmic scale)

Region of sufficiently
stable management(March 2022)

Fuels incommonpool

Fuels indry casks

Rubble instoragefacility

Fuel debris

Contaminatedstructures in bldgs. Unit 1
ALPS Unit 3
slurryUnit 2
Waste
Unit 2 Fuels inabsorption
Waste
SFPs
columnssludgeConcentrated
ALPS Unit 1
liquid waste,slurryetc. (to be transferred to other HICs)
Stagnant waterin bldgs
Zeolitesandbags
Stored water
Color-coding of risk
in welded tanks Residual water
sources withreference to the Midin flanged tanks
and-Long-term
Soil covered
Roadmap *temporarystorage, etc.
Outdoorstorage, etc.

Safety Management (logarithmic scale)* Risk sources that are "relatively high risks given high priority" are shown in pink, those that are "immediaterisk unlikely, but risk may grow when handling with haste" are shown in yellow, those that are "increased risk
unlikely in the future, but appropriate decommissioning efforts are required" are shown in green, and those thatare in the "sufficiently stable management" region are shown in light blue.
The red letters present risk sources that have changed significantly from the evaluation of the TechnicalStrategic Plan 2021 (as of March 2021).
The origin of the arrow indicates the location for the residual water in flanged tanks reported in the TechnicalStrategic Plan 2021, which has been moved upward to reflect the results of the analysis of the radioactivity
concentration prior to the treatment. ALPS slurry (to be transferred to other HICs) was separated from ALPS slurry
this time and shown in pink, as is the fuel in the pool.

Fig. 3 Risk levels posed by the major risk sources at the Fukushima Daiichi NPS
2.2.2 Risk reduction strategy
2.2.2.1 Interim targets of the risk reduction strategy and progress
Measures for risk reduction include the reduction of the "Hazard Potential" and the reduction ofthe "Safety Management" level. Of the various risk reduction measures, reduction of the "Safety
Management" level is generally considered to be easily realized. Consequently, thedecommissioning of the Fukushima Daiichi NPS, which is implemented under the basic policy of"to continuously and quickly reduce the risks arising from the radioactive materials caused by theaccident and that do not exist in normal nuclear power plants" (refer to Section 2.1), should first
focus on steadily managing risk sources by keeping them in higher-integrity facilities to lower their
Safety Management levels. The interim target of the risk reduction strategy is to bring the risk levels
into the "Sufficiently stable management" region (the pale blue area) as shown in Fig. 3.
Regarding the progress of work from Technical Strategic Plan 2021 toward this goal, Fig. 3 shows
the status of treatment of the residual water (concentrated salt water) at the bottom of the flanged

11

tanks, and the need to replace some high integrity containers (hereinafter referred to as “HIC”s)storing ALPS slurry in consideration of the effect of β-ray irradiation.
Of the residual water in flanged tanks, sludge sedimentation containing α-nuclides has been
confirmed in the tanks that received the residual bottom water when dismantling tanks in each tankarea, recovery of the remaining water is currently underway. Supernatant water has beentransferred to the process main building, and the water level is lower than assessed in the TechnicalStrategic Plan 2021. Only one tank contains residual water, including the sludge, and the collectionof the sludge through a filter is being carried out. In evaluation incorporating total α-nuclides
concentrations and the high strontium concentrations identified by the analysis of radioactive
concentrations prior to the treatment (analysis of the residual water sampled from two tanks on July
21 and August 5, 2021), high strontium concentrations have a significant impact, thereby increasing
the hazard potential compared to the Technical Strategic Plan 2021. However, it is a reflection of
the findings from the analysis and does not indicate the risk itself has increased. Not only in thiscase, but in other cases, there is uncertainty in risk source information. If an assessment isconducted based on estimates with limited information or fragmentary sampled data, there is apossibility of the risk being underestimated or overestimated.
Regarding the ALPS slurry, among the HICs affected by β irradiation, those accumulated
absorbed doses have exceeded the criterion value of 5,000kGy (accumulated absorbed dose withconfirmed HICs structural integrity against drop1) or are evaluated to be close to exceeding thecriterion value, and those ALPS slurry are planned to be transferred to other HICs by the end of
FY2023 is shown in pink in Fig. 3. Since the number of HICs whose accumulated absorbed doseis close the criterion value will gradually increase with time, it is important to carry out transfer
operation steadily and manage not exceeding the criterion value. To this end, the slurry stored in
HICs that exceeds the criterion value should be eliminated by systematically transferring them by
the end of FY2023. After that, the transfer operation should be made before the criterion value is
exceeded in a systematic manner. In addition, an early transition to storage in containers with longterm integrity leads to an intrinsic reduction in the risk of deterioration over time. TEPCO isreviewing the design of containers with long-term integrity in the design for stabilizing slurry, andthis should be promoted without delay. As the decommissioning work becomes more prolonged,
important actions are monitoring and managing risk sources in consideration of the deterioration offacilities and systems and promptly bringing risk sources to a stable and controlled state.
In considering the station-wide risk reduction strategy for the Fukushima Daiichi NPS, the abovementioned SED is a quantitative indicator of risks attributable to radioactive materials at a certain
time, and is an effective method for prioritizing risk sources for risk reduction.

1

The allowable strain was established from the material test results of HIC polyethylene specimens irradiatedwith 5,000kGy of beta radiation, and the maximum strain obtained from the drop analysis was less than theallowable strain.

122.2.2.2 Risk reduction process for major risk sources and its progressFig. 4 shows the process to bring major risk sources into the “Sufficiently stable management”
region as the interim goal, and an example of representing the decommissioning work progressalong this process. Fig. 4 (a) shows the outline flow of the decommissioning work to date and thefuture plans to represent the overall decommissioning process in a comprehensive way. Using thecoloring in Fig. 3 to indicate the risk level of each risk source, Fig. 4(a) also shows the flow of risk
reduction. Based on this flow, it is possible to visualize how the risk sources have changed
compared with the time of the accident by applying it to fuel debris, spent fuel, and Cs-137 released
during the accident. As changes from Technical Strategic Plan 2021, the treatment process of theresidual water in the flanged tanks (sludge recovery by water filtering) are shown, and the ALPS
slurry is indicated in green and pink, some ALPS slurry is planned to be transferred in light of the
impact of β irradiation. The number of spent fuel assemblies as an indicator to make the work
progress easier to see in Fig. 4 (b), and for Cs-137, the estimated radioactivity (Bq) common tovarious risk sources as an indicator in Fig. 4 (c) both indicate the progress of the decommissioning
work by representing the status of transition to the “Sufficiently stable management” region in a pie
chart format. Fig. 4 (b) has made no progress since Technical Strategic Plan 2021. Fig. 4 (c)incorporates the increase/decrease in Cs-137 due to the decrease in the stagnant water in buildings,
the increase in waste sorption vessels, the increase in the storage volume in solid waste storage,
and the increase of attenuation in FY 2021. In this Figure, the significant increase in the percentage
of attenuation is shown in light gray. In light of the impact of β irradiation, the ALPS slurry stored in
HICs to be transferred is transferred to the pink area.

13

Color-coding is the same as in Fig. 3
Arrows show the diffusion/processing flow of risk sources.
Dotted lines indicate the scope of future studies and being studied.

Category

Sufficiently stable
management condition

Processing

Risk source

Reducing risks by processing

Fuel debris

Fuel debris inside
PCV

Retrieve

Temporary storage
for fuel debris

Storage for fuel debris

Spent fuelSpent fuel pool

RemoveCommon Spent
Fuel Storage PoolDry cask※2※3

Cs-137
released during
the accident

Stagnant water inbuildings

Purify Cs/Sr

Welded tanks(Sr-treated water)

Removemultinuclide

Water
filtering*１

Residual water inflanged tanks

Filtered water* 2, *３
Concentrateby evaporation(Operation stopped)

Concentrated liquid
waste, etc.

Sludge *４

Solid waste
storage facility

Dehydrate/stabilize

ALPS slurry(Incl. to be transferred to（高線量HIC含む）
other HICs)*１

Welded tanks(ALPS-treated water)

Temporary storageof used columns

Decontaminate(Operation stopped)

Waste sludge
Collect/stabilize

Zeolite sandbags

Contaminatedstructures in bldgs

Dismantle/
RemoveOutdoor storage, etc.

Reducevolume, etc.

Rubbles, Felled trees, etc.

*１ Connect the arrow from
“Remove multi-nuclide”*２ Connect the arrow from
“Water filtering”*３ Connect the arrow from
“Water filtering”(For detail in progress)*４ Place to be stored is being
arranged.

Soil-covered, etc.

Discharge into theenvironment(a) Risk reduction process
Residual water in the buildings
Additional
事故時に放出されたCs-137
and ALPS slurryattenuation(to be transferred to other HICs)(FY2021)Spent fuelstored in SFP

Fuel transported toCommon Spent Fuel
Storage Pool after theaccident

AttenuatedEnvironmental
discharge

ContaminatedStructures inbuildings, etc.

Solid waste
storage facility
Sorptioncolumns, etc.
Zeolite sandbags, etc.

*New fuel not included(b) Number of fuel assemblies of spent fuel(Units 1 to 4)(c) Radioactivity of Cs-137 released at the accident(Units 1 to 3)

Fig. 4 Risk reduction process for major risk sources and its progress (example as of March 2022)(Attenuation in Fig. 4 (c) takes into account radioactive decay of Cs-137 from the time of theaccident to the end of March 2022)

14

2.2.2.3 Basic approach to risk reduction
The decommissioning of the Fukushima Daiichi NPS is a project that involves considerable
uncertainties. To date, the internal status of the PCVs of Units 1 to 3 has been estimated to someextent through simulation of the accident development process, estimation of the places with fueldebris by muon-based fuel debris detection technology, placement of investigation equipment into
the PCVs, radiation dose measurement and video photographing in the buildings, and other means.
However, there are still significant uncertainties. Eliminating these uncertainties requires many
resources and, in particular, a considerable amount of time. In order to realize prompt reduction ofrisk, it is necessary to promote the decommissioning work through a flexible and prompt approach,based on the directions determined with previously obtained experience and knowledge, and withexperiment and analysis-based simulation, making safety the top priority, even though uncertainties
remain to a certain extent.
Regarding the perspective from which these comprehensive decisions will be made, NDF
summarizes the following five guiding principles:(Five guiding principles)➢ SafeReduce the risks posed by radioactive materials and ensure work safety➢ Proven

Highly reliable and flexible technologies➢ Efficient

Use resources effectively (e.g., people, things, money and space)➢ Timely➢ Field-oriented

Be conscious of timeComprehensive three-reality policy by checking actual site, actual things,
and actual situation

In applying the five guiding principles to the actual site, it is important to proceed with thedecommissioning operation after greatly emphasizing safety assurance for the purpose ofprotecting human beings and the environment from the radioactive materials associated with theoperations, thoroughly conducting radiological impact evaluations, and taking appropriate
radioprotective measures. ("Safe in the five guiding principles")In the decommissioning of the Fukushima Daiichi NPS, because the public risk level is risingwith time as the degradation of facilities damaged by the accident progresses, controlling this risk
to be as low as reasonably achievable ("Efficient") as promptly as possible ("Timely") in light of thesituation at the site, and proceeding with the decommissioning in a reliable manner ("Proven") by
feasible ways in the harshest on-site state ("Field-oriented") will lead to ensuring safety in themedium-to-long-term.
As for the result judged based on these guiding principles, it is also important to work todisseminate information carefully so that the results will be widely accepted by society.

152.3 Approach to ensuring safety during decommissioning
2.3.1 Basic policy for ensuring safety based on the characteristics of Fukushima Daiichi
NPS
Decommissioning of the Fukushima Daiichi NPS containing the reactors involved in the accident
is an unprecedented activity that takes place in a peculiar environment different from that of anormal reactor, and therefore, to ensure safety, the following characteristics (peculiarities)
regarding safety should be fully recognized:•

A large amount of radioactive material (including α-nuclides that have a significant impact
in internal exposure) is in an unsealed state, as well as in unusual (atypical) and various
forms

•

Barriers for containing radioactive materials, such as reactor buildings and PCVs, areincomplete•

Significant uncertainties exist regarding the state of these radioactive materials andcontainment barriers, etc.

•

Difficulty in accessing the site and installing instrumentation devices to obtain on-site
information due to constraints such as high radiation levels on site•

Since the current level of radiation is high and further degradation of containment barriers
is a concern, it is necessary to take measures in consideration of the time axis without
prolonging the decommissioning activities

Consequently, TEPCO, as the operator of the decommissioning project, needs to pay special
attention to the following points in proceeding with the decommissioning based on the five guiding
principles.
Firstly, with regard to "safety": There is great uncertainty about the state of radioactive materials
and containment barriers, and on-site access and installation of instrumentation devices to reduce
the uncertainty are also restricted. Under these circumstances, a large amount of atypical andunsealed radioactive material will be handled in an incomplete state of containment. Therefore, thestarting point for all reviews should be confirmation of the feasibility of ensuring safety with a wide
range of possibilities (cases) assumed. At the same time, with regard to "safety", it is important not
to prolong the work period in light of risk reduction over the entire work period. Therefore, it isnecessary to avoid excessive safety measures and to take optimum safety measures (ALARP).
Such perspective on "safety" (the safety perspective) should be reflected in the decommissioning
work review.
Secondly, with regard to "field-oriented":•

The on-site environment is in a peculiar state that includes a high level of radiation, andtherefore attention should be paid to the feasibility of construction/implementation of safetymeasures on site.

•

An approach through design alone has limitations due to significant uncertainties.

16

From the above-mentioned reasons, it is essential to accurately apply the information gained onsite into engineering. In order to ensure the implementation of unprecedented engineering such asfuel debris retrieval, the views and feelings of the individuals and organizations (operators) that are
responsible for the on-site work (including operation, maintenance, radiation control,
instrumentation, analysis, etc.) and very familiar with actual site should be highly respected.
Moreover, it is important to respect their perspectives and judgements directly based on the site(the operator's perspective). In promoting the prolonged decommissioning work, it is necessary tomaintain and strengthen the operator's perspectives/feelings, and TEPCO themselves should
inherit their perspectives. Therefore, TEPCO needs to take action that always accounts for theworksite in the overall decommissioning work process, such as by inviting outside experts andtechnicians with operator's perspectives for coaching/educational training, including experienced
workers in difficult operations and those who experienced on-site operations.
This section describes the importance of the safety assurance measures in terms of thecharacteristics of Fukushima Daiichi NPS based on safety assessment which includes theoperator's perspective. Then, it describes the operator's perspective-specific importance thatshould be incorporated at multiple levels in the safety assurance process.
2.3.1.1 Optimization of judgement with a safety assessment as its basis and ensuring
timeliness in decommissioning
With an aim of reducing risk through decommissioning, it is most important to take appropriate
measures and ensure the safety of work in which a large amount of radioactive material is handledthat is technically difficult and has significant uncertainties, such as fuel debris retrieval. Thus,
decommissioning work should be carried out with such "safety perspective".
Specifically, when designing safety measures for each decommissioning activity, it is essential
to make decisions based on the five guiding principles after conducting a thorough safety evaluationand confirming that the required safety is ensured. As mentioned above, the decommissioning workof the Fukushima Daiichi NPS is unprecedented and has significant uncertainties. Using
deliberated safety evaluation as the basis for making decisions regarding safety measures, thedecisions will not be significantly unstable (that is, without devoting too little or excessive resources),and thus necessary, sufficient, and reasonably feasible safety measures can be realized(optimization of judgment based on safety assessment). In regard to reasonably feasible safetymeasures, it is particularly important in the safety assessment of the Fukushima Daiichi NPS to
conduct safety assessment with incorporating operator's perspective stated in 2.3.1.2.
In addition, the importance of making progress in the decommissioning work without delay (theimportance of time-axis-conscious action) can be mentioned as "the safety perspective" unique tothe decommissioning of Fukushima Daiichi NPS. Considering the high radiological impact that has
already materialized, and the possibility of further degradation of containment barriers, etc., making
progress in the decommissioning work without delay will have great significance for ensuring thesafety of the entire decommissioning process from a medium-and-long term perspective. Therefore,17

it should be noted, for ensuring safety, that different perspectives from normal reactors are required,
which have a certain margin in terms of human, physical, and financial resources and have low
radiological impacts and high stability. On the condition that safety is secured, rational judgement
should be made on resource allocation and the time-axis-conscious progress in thedecommissioning work without delay based on the relationship with the overall balance (ensuring
timeliness in decommissioning activities).
2.3.1.2 Ensuring safety by incorporating "the operator's perspective"
To ensure that safety measures are truly effective, it is necessary to satisfy the needs from thestandpoint of those who actually perform the operations and tasks on site, "the operator's
perspective" (perspectives and judgements from the standpoint of those who are familiar with thesite and perform operations and tasks on site) is important. In addition to this standpoint, when
determining the feasibility of safety measures in decommissioning the Fukushima Daiichi NPS, it
is necessary to take into account the fact that the facility has suffered from the accident, and its
decommissioning requires an unprecedented approach in a peculiar environment, such as one withhigh radiation levels, unlike normal reactors.
2.3.2 Preliminary implementation and utilization of the obtained information in the latterstagesThe on-site conditions at the Fukushima Daiichi NPS containing the reactors involved in theaccident includes considerable uncertainties. If the whole operation of a large-scale project suchas fuel debris retrieval is to be designed only with existing knowledge, assumptions of an extremely
large safety margin and wide range of technical options will be needed. Thus, extension of the work
period or the risk of rework will be unavoidable. As a result, the feasibility or predictability of theentire project may be reduced, leading to a delay in the entire decommissioning, a rise in thedecommissioning cost, or increased radiation exposure of workers.
However, considering the environment with an already high radiation level, further deteriorationof containment barriers, and the possibility of future major natural events (such as earthquakes ortsunamis), it is necessary to immediately improve the state of such risks and reduce uncertainties.
Therefore, a "sequential type approach" is important where the whole operation is divided into
several stages, "operation at first stage" is implemented for which practical safety can be ensured,and then the information obtained there is utilized in the next stage. With this approach, operation
proceeds with safety ensured through monitoring the condition inside reactor, restricting operational
actions and flexible on-site responses at each stage of the process. The information obtained ateach stage of operation and testing is utilized in the design of subsequent stages. This approach
reduces uncertainties in the operations in subsequent stage as well as improve the reliability ofsafety assurance and rationalize design.
TEPCO should actively introduce an approach like this into actual engineering and project
management.

18

Hereafter, it is recommended to make sequential type approach clear as a policy, in which theinformation to be gained through on-site operation should be fully incorporated and accumulated
as knowledge for ensuring safety. For example, in the reactor water injection shutdown tests thatTEPCO has been conducting since FY 2019, the risk associated with water injection shutdown has
been identified, and knowledge has been accumulated. In the future, efforts should not be limited
to identifying risks and accumulating knowledge during the shutdown of water injection but should
be expanded to account for acquiring a basis that contributes to the design of water injection
systems for fuel debris retrieval.
It is important to accumulate successful/unsuccessful experience gained in the process of thesesequential approach as a track record, allowing gradual reduction in major uncertainties in theoverall decommissioning work in the future. This will lead to steady progress in decommissioning
and contribute to ensuring safety in decommissioning the Fukushima Daiichi NPS from theperspective of risk reduction in the medium-and-long term.
The approach to risk reduction and ensuring safety in the decommissioning of the Fukushima
Daiichi NPS, as described in this chapter, needs to be promoted with the broad understanding of
not only the people directly involved but also the local people. Consequently, it is necessary tocooperate with each other to reduce risks based on the approach to ensuring safety based on theirrespective positions. In doing so, it is important to establish a system for on-going risk monitoring
which enables a wide range of people to easily understand how the overall risks at the site havebeen continuously reduced through the decommissioning work, and to communicate such progressto the public. In addition to sharing the status of risks through the Technical Strategic Plan on aconstant basis, NDF is considering providing the status of risk reduction along with the progress ofthe decommissioning work described. TEPCO also needs to develop a mechanism to identify risks
for the entire site and become aware of the need to take action to communicate the status of risk
reduction to society in a proactive manner.

19

3. Technological strategies
Fukushima Daiichi NPS

towarddecommissioning

of

the

3.1 Fuel debris retrieval
3.1.1 Targets and progress(Targets)(1) Retrieve fuel debris safely after thorough and careful preparations, and bring it to a state ofstable storage that is fully managed.
(2) Trial retrieval in Unit 2 was scheduled to begin within 2021, but the process will be reviewed
to improve work safety and reliability during retrieval in light of the impact of the COVID-19
pandemic, ongoing mock-up tests at the Naraha Center for Remote Control Technology
Development since February 2022, and the status of the on-site preparatory work in Unit 2,
and trial retrieval is expected to begin in late FY 2023. Continue a series of work, including
gradual expansion of fuel debris retrieval, to acquire the knowledge and experience necessary
for further expansion of fuel debris retrieval in scale.
(3) With regard to further expansion of fuel debris retrieval in scale, consideration will be given to
the methods including those for containing, transferring, and storing of fuel debris, byassessing fuel debris retrieval in Unit 2, internal investigations, research and development,
and the on-site environmental improvement, etc.
(Progress)①

Unit 1

PCV internal investigations have been conducted using a boat-type access investigation device
with a diving function (hereinafter referred to as “underwater ROV”), which can be equipped withvarious measurement sensors. The underwater ROV is inserted into the PCV through thepenetration X-2 to access the basement floor outside the pedestal. So far, visual investigations anddeposit thickness measurements have been in progress. In the visual investigations, lump deposits
have been observed outside and inside the periphery of the worker access opening in the pedestal.
However, whether they are existing structures or fuel debris has not been determined. In addition,
reinforcing bars were observed in the vicinity of the worker access opening, and it was confirmedthat concrete in the pedestal area was partially missing. Regarding this matter, IRID conducted aseismic assessment of the partially damaged pedestal in FY 2016 under the Project ofDecommissioning and Contaminated Water Management and confirmed that its supporting
function was not significantly impaired.
Further investigations are planned to observe the distribution of deposits widely scattered at thebottom of the outside of the pedestal, the presence or absence of fuel debris in deposits,
sampling/analysis of deposits, and the condition of structures inside the pedestal.

20

②Unit 2The 2019 Mid-and-Long-term Roadmap specified Unit 2 as the first implementing unit where fueldebris retrieval would be implemented, and trial retrieval was supposed to launch within 2021. The
process has been delayed due to the impact of the COVID-19 pandemic, work proceeded to limit
the delay to about one year.
Then, after completing the manufacture and verification tests of the arm-type access equipment(hereinafter referred to as “robot arm”) in the UK in June 2021, the equipment was brought to Japanand has been undergoing performance confirmation tests, mock-up tests, and training at thedomestic factory (Kobe) since July 2021, and at the Naraha Center for Remote Control Technology
Development, JAEA since February 2022. Modification and verification of the control softwareand improvements to some equipment, which are new requirements based on these tests, arebeing progressed. Furthermore, the plan is to expand one-through testing for higher reliability.
In addition, as on-site preparatory work, installation of the isolation chamber for opening hatchof the penetration X-6 started in November 2021. As countermeasures for the damage to the box
rubber and the bent guide rollers (in response to the earthquake) in the isolation chamber that
occurred during installation, replacement of the rubber box with metal plates, cutting off hatch
handle of the penetration X-6, and structural changes to the guide roller are planned. In the future,
work feasibility will be verified through factory mock-up testing. Remanufacturing of the isolationchamber is also under consideration in case any issues are identified in the verification results andinstallation condition of the isolation chamber after implementing countermeasures. As operations
such as opening of the penetration X-6 hatch and removal of deposits in the penetration X-6 areplanned, work should be carried out safely and carefully.
As described above, given the response status based on the mock-up test of the robot arm andthe arrangement of countermeasures in on-site preparatory work, it has been decided to add
another 1 to 1.5-years to the preparation period along with the preceding delay of about one year
due to the impact of the COVID-19 infection to improve work safety and reliability and to change
the process to start trial retrieval in late FY 2023.
A plan for the gradual expansion of fuel debris retrieval is also underway, and the retrieval device
will be improved by increasing the weight capacity and enhancing accessibility while complying
with specifications for the devices for trial retrieval (internal investigations and fuel debris sampling).
In this plan, the requirements related to performance of the robot-arm and enclosures and therequirements at the design and installation have been clarified and examined. The retrieved fueldebris will be stored in container for fuel debris retrieval and transport container in the enclosure,and then transferred to the receiving/delivery cells on site and stored in temporary storage cells. In
addition, some of the fuel debris will be collected in the receiving/delivery cells for analysis andtransported to the facility for analysis. Designing of the retrieval device, receiving/delivery cells, andtemporary storage cells is in progress (Fig. 5, Fig. 6).

21

③

Unit 3

Regarding Unit 3, due to the high water level in the PCV, the plan is to lower the PCV water levelin two steps, taking into account the conducting of the PCV internal investigation and the improved
seismic resistance of the S/C. The plan for lowering the water level in Step 1 was to drain the PCV
water by self-suction pumps using the existing pipe connected to the S/C to reduce the current
water level below the first floor surface of the reactor building. However, after the earthquake on
March 16, 2022, it was confirmed that the PCV water level was gradually declining. After the startof the planned reactor water injection shutdown tests in June, water injection was resumed tocontinue water level measurement because it was determined that the PCV water level had fallen
below the lower end of the new PCV thermometer/water level gauge. After that, the amount of water
injection was adjusted in July, confirming that the PCV water level was generally stable. Based on
the above circumstances, for the plan to lower the water level in Step 1, monitoring of plantparameters will be continued, and a reduction of the amount of water injection or the shutting downof water injection will be discussed to install instruments at lower locations than current levels andlower the PCV water level. In Step 2 in the future, the plan is to connect the guide pipe to the S/C
and lower the water level to the bottom of the S/C by underwater pumps installed inside the S/C.
Although retrieval methods for further expansion of fuel debris retrieval in scale were examinedin the conceptual study, many challenging issues and risks associated with each discussed method
were identified. Since FY 2022, studies have been conducted on countermeasures for these issues
and risks from the perspective of feasibility.

(Prepared by NDF based on TEPCO and IRID materials)

Fig. 5 Image of fuel debris retrieval system(Trial retrieval and subsequent gradual expansion of fuel debris retrieval)

22

(TEPCO material edited by NDF)

Fig. 6 Image from retrieval to temporary storage of fuel debris

3.1.2 Key issues and technical strategies to realize them
Since the understanding the situation inside the PCVs is still limited, the current design and theplan for on-site operations related to fuel debris retrieval should be continuously reviewed basedon knowledge that will be obtained in the future, and it is also important to accurately incorporate
the results of studies, research and development toward fuel debris retrieval.
The trial retrieval (internal investigation and fuel debris sampling) in Unit 2 will be the first retrievalof fuel debris, and it is necessary to make steady preparations to utilize the valuable informationand experience obtained through these works in subsequent retrieval operations. Thereafter, thegradual expansion of fuel debris retrieval will be implemented based on the findings obtained fromthe retrieval in Unit 2. In addition, a conceptual study on further expansion of fuel debris retrieval inscale for Unit 3 is planned.
Since each unit is in a different situation, this section first describes each unit's fuel debris
retrieval strategy in 3.1.2.1, followed by the strategies for trial retrieval (internal investigation andfuel debris sampling) in 3.1.2.2, and gradual expansion of fuel debris retrieval in 3.1.2.3, and further
expansion of fuel debris retrieval in scale in 3.1.2.4. This chapter then describes the continuous
accident analysis activities in 3.1.2.5, technical issues for technical requirements, and future plansin 3.1.2.6.
3.1.2.1 Fuel debris retrieval strategies in each Unit
(1) Unit 1
 Toward further expansion of fuel debris retrieval in scale, the retrieval methods should be
examined by promoting R&D and engineering to apply the results on-site and based on theknowledge gained through trial retrieval in Unit 2 and the initial study results of the method for
Unit 3.
 In the ongoing PCV internal investigation, the condition of the existing structures and distribution
status of deposits outside the pedestal are being confirmed, an investigation inside the pedestal
through the worker access opening is also scheduled. However, although the previous

23investigations and analyses using muon have evaluated that there is almost no fuel debris in thecore, they were not direct investigations. Thus, a direct video investigation is required in a future
study. As technological development for this purpose is in progress, the information obtained
from these investigations should be incorporated as necessary when examining retrieval
methods hereafter.
 The size of the RPV and PCV is smaller than Units 2 and 3 due to a lower plant output, and thelayout of plant systems also differs. In addition, although it is expected to be clarified in a future
investigation, the distribution of deposits inside the RPV and inside/outside the pedestal isconsidered to be different from Units 2 and 3. Therefore, it is necessary to examine retrieval
methods considering these differences.
(2) Unit 2
 Preparations for trial retrieval are underway, and the plan is to gradually expand fuel debris
retrieval. However, since there is no plan to retrieve all the fuel debris using the side-accessmethod, it is necessary to examine methods for the further expansion of fuel debris retrieval inscale.
 Toward the gradual expansion of fuel debris retrieval, it is necessary to advance R&D andengineering for applying the results on-site, and then to promote design, manufacturing, andinstallation of fuel debris retrieval systems, safety systems (e.g., containment, fuel debris cooling,
criticality control), temporary fuel debris storage, and maintenance systems for retrieval systems,
based on the knowledge gained through trial retrieval.
 Toward further expansion of fuel debris retrieval in scale, it is necessary to examine the retrieval
methods based on the knowledge gained through retrieval in Unit 2 and the initial study resultsof the method for Units 3.
 The previous PCV internal investigations (inside the pedestal) and investigations/analyses using
muon indicated that a large amount of fuel debris is at the RPV bottom and there is a possibilityof some fuel in the core, and this needs to be considered when examining retrieval methods.
Furthermore, although it is unlikely that the fuel debris that fell to the PCV bottom has spreadoutside of the pedestal, no investigation has been conducted inside the RPV and outside thepedestal. Thus, a direct video investigation is required in a future study.
(3) Unit 3
 As described in 3.1.2.4 below, retrieval methods are being examined to further expand fuel debris
retrieval ahead of other units. From FY 2022 onward, the actual site applicability and technicalfeasibility should be studied for the issues and risks to be examined in greater depth.
 Previous PCV internal investigations (inside the pedestal) revealed that the control rod drive
housing support has partially fallen and deformed, several structures have fallen on the lower

24

part of the pedestal, including structures presumed to be structures inside reactor, and that there
are deposits assumed to be fuel debris. According to muon surveys and analyses, it is estimatedthat a larger amount of fuel debris than in Unit 2 may have fallen into the pedestal and spreadout of the pedestal through the worker access opening. In order to improve the reliability of themethods to be selected, it is necessary to consider survey planning to observe the distribution ofdeposits outside the pedestal, consider additional investigations in the pedestal and the RPV andincorporate these investigation results into the examination and design of the methods.
 When examining retrieval methods, it is necessary to examine containment facilities considering
the damage to the reactor building.
(4) A common strategy for each unit The PCV internal investigation of Unit 1 confirmed that the pedestal was partially damaged.
However, in past research and development, it was confirmed that its supporting function was
not significantly impaired in the seismic evaluation assuming the extent of the damage. Alongwith expanding knowledge through internal investigations, it is also necessary to discuss theevents during the accident, assumed from the fact that hot deposits (fuel debris) flowed out ofthe pedestal. Based on these discussions and knowledge, removal methods of deposits insideand outside the pedestal and the possibility of deposits flowing into the S/C should be examined,
while incorporating the findings gained from internal investigation into fuel debris retrieval
methods, including for other units.
 Information about the inside the PCV of each unit obtained so far is limited, and there are many
areas where direct video information is not available. Therefore, additional internal investigationof the PCV and RPV of each unit should be considered to promptly collect more information,
including the condition of the damage at the RPV bottom and the presence or absence anddistribution of deposits outside the pedestal. Gaining such information at an early stage enables
verification of the direction of the fuel debris retrieval strategy to be pursued in the future, leading
to engineering with less regressing.
 After analyzing and clarifying the causes of a number of on-site problems experienced in the onsite decommissioning work to date, improvements should be made, including in the organizationand structure, and consideration should be given to incorporating measures to prevent
recurrence into the next phase of the work. Planned fuel debris retrieval requires developmentof a method that can eliminate the potential risks based on these experiences, and for risks thatcannot be eliminated, preparing a response plan if these occur in advance.
 Fuel debris retrieval, including preparatory work, will be executed in a high-dose, severe site
environment. Although remote devices are used under various circumstances, workers will have
many on-site operations to reduce radiation dose on-site, prepare for the removal of the existing
structures, and prepare and arrange equipment for use. The maintenance of remote devices and25

restoration in case of failure also need to be considered. It is necessary to examine methods
considering the entire field work sequence from preparation to retrieval and select methods thatenable retrieval even if all on-site conditions cannot be identified and methods (robust method)
not easily affected by external events such as earthquakes.
 Although the amount of remaining fuel debris differs, it is assumed that fuel debris exists in the
RPV of each unit. Therefore, in the partial submersion method, using side-access only, which isconsidered to have limited access to the inside of the RPV, is not sufficient to cope with thesituation, and top-access is also required. Therefore, it is considered essential to accelerate thedevelopment and engineering of the top-access method again and then examine the fuel debris
retrieval method using a combination of top and side access methods. From this perspective,
examinations will be made on the methods, operation procedures, shielding systems and cellstructures to be installed on the operating floor, fuel debris and waste transfer flow, andclassification of contamination control.
3.1.2.2 Development status and prospects of trial retrieval (internal investigation and fueldebris sampling)
For the trial retrieval (internal investigation and fuel debris sampling) in Unit 2, the operation will
be performed by opening the flange of the penetration X-6 to make a larger opening than before,
through which the robot-arm is moved in/out to retrieve fuel debris inside the PCV. In this operation,
an expansion will be made to provide an isolation chamber to be built during opening thepenetration X-6, and an enclosure to be newly provided, since the conventional containment barrier
was located in the close flange part of the penetration X-6. Although small in scale, this is afundamental form of site construction for future retrieval work, in which an opening will be newly
provided in the PCV to extend the containment barrier outside the PCV. This presents an approachthat enters a new stage.
As described above, trial retrieval (internal investigation and fuel debris sampling) is entering a
new phase, and the series of work described below should be carried out in a phased manner (SeeFig. 7). Moreover, due to the uncertainty of the conditions inside the PCV, it is necessary to proceedwith the work safely and carefully, bearing in mind that additional work or rework may be required
depending on the actual on-site situation and that the work may not go as planned. Furthermore,each of these operations has no precedent, and it is very important to utilize the valuable
information, experience, etc. gained through them in subsequent retrieval operations. In addition,
it is important to consider in advance troubleshooting and a system for a prompt response to gowith it.
(1)

Preparatory work (completed)[1] Environmental improvement around the penetration X-6 in the reactor building[2] Hole diameter enlargement of the penetration X-53

26

(2)

Installation of an isolation chamber (isolation room inside stage, hatch isolation room,
robot carry-in room) (in progress)(3)

Opening of the penetration X-6 hatch by hatch releasing apparatus(4)

Removal of deposits in the penetration X-6 by deposit remover(5)

Robot arm installation (removal of the robot carry-in room, installation of the penetration
X-6 connection structure, extension pipe, and enclosure)(6)

Robot arm entry (penetration X-6 - CRD opening - inside the pedestal), surrounding check,and removal of obstacles (Abrasive water jet)

(7)

Internal investigation and fuel debris sampling by robot arm[1] Internal investigation from the PCV inlet to outside the pedestal[2] Internal investigation inside the pedestal (above the grating, PCV bottom, etc.)[3] Sampling from the inside the pedestal (sampling from above the grating and PCV bottom,
etc., is under consideration)(8)

Storage to shipping containers from fuel debris retrieval equipment, and dose
measurement(9)

Acceptance into glovebox and measurement(10)

Removal of containers, storage in shipping containers, and carry-out(11)

Off-site transport and off-site analysis (analysis of fuel debris properties)

Regarding preparation status of trial retrieval (internal investigations and fuel debris sampling),
it is expected that the production and installation of the required devices, site preparation, andinstallation of glovebox for transporting retrieved fuel debris will be completed, workers including
operators of various equipment/devices required for retrieval and on-site leaders will be secured,and the framework for verification tests, mock-up tests, training, and retrieval will be established by
the end of Phase 2 of the Mid-and-Long-term Roadmap.
Verification tests of the newly developed robot arm were conducted in Kobe (Kobe Shipyard &Machinery Works, Mitsubishi Heavy Industries) from July 2021 until January, 2022, following
verification tests at a factory in the UK. Since February, verification tests (mock-up tests) have been
conducted in an actual simulated environment using the mock-up facility at the Naraha Center for
Remote Control Technology Development (JAEA), which covers the entire PCV from thepenetration X-6 and beyond.
It is important for on-site applications with uncertainty to ensure functional verification checks
under various conditions and equipment can be rescued in case of emergency. Therefore, it isnecessary to make the preparations needed, ensure that the required functions are satisfied byconducting mock-up tests that simulate the actual site even if it takes time, and ensure that newly
identified risks are eliminated. This process needs to be reiterated when necessary. For example,
mock-up testing at the Naraha Center for Remote Control Technology Development, progress isunderway to modify and verify control software and improve some equipment, both of whichbecame additionally required based on the results of verification tests in Kobe and in the UK.
27

Moreover, the plan is to expand one-through testing for higher reliability. Furthermore, it isnecessary to thoroughly prepare the measures required for the practical application, not only bysimulating severe environments on site in mock-up testing, but also by making clear any areas thatare not simulated.
In constructing the access route on-site, the installation of the isolation chamber has been
delayed due to the unevenness of the floor at the location of the isolation room inside stage andairtight leakage-proofing in the hatch isolation room, etc. After installation of the robot isolationchamber is completed, the plan is to open the hatch of the penetration X-6, remove deposits inside
the penetration X-6, and establish the penetration X-6 connection structures and the enclosure(with a built-in robot arm, etc.).
During the installation of the isolation chamber, leakage from the newly installed in-stage isolationchamber was observed in an airtight leak test (leakage from rubber containment barrier). This event
reaffirmed that expanding the containment barrier outside the PCV, which interfaces with theexisting structures in a high-dose environment, would be a challenging task. It was also reaffirmedthat since heavily equipped workers need to be replaced in a short time for operations in a highdose environment, it is always necessary to ensure quality and safety in performing work. Moreover,in the future, when the installations of apparatus such as the robot arm system that are interfacingwith the existing structures outside the PCV to extend the containment barrier, it will also be achallenging task in a high-dose environment. Thus, careful preparation based on this event will benecessary. In addition to the above, paying full attention to the unique characteristics of Fukushima
Daiichi NPS, such as the fact that containment barriers are imperfect and uncertain, and thatearthquakes are expected to occur in the future, work descriptions should be reviewed again andoperation training should be provided to enhance future work safety and reliability. It is also
necessary to incorporate above features, knowledge and experience gained this time into
examining fuel debris retrieval methods after the gradual expansion of the retrieval scale.
Given the above events, equipment should be deployed on-site after sufficient performance andoperational verification.

28

(1) Preparatory work (completed)
Cutting machine (hole saw)

●Prework for spray jig installation(Hole diameter enlargement of thepenetration X-53)(6) Robot arm entry(7) Internal investigation and fuel debris sampling① Internal investigation by robot arm(2) Installation of an isolation chamber (in progress)●Isolation chamber
installed prior to opening
hatch⚫ Remove obstacles (CRD rail,
conduit) with【AWJ】at theend of the arm②Fuel debris sampling by robot arm
Tip of fuel debris retrieval device(3) Opening of the penetration X-6<Wire brush type>

Hatch releasing apparatus●Opening of the hatchof penetration X-6 byhatch opener<Vacuum vessel type>(Note) - Isolation valve : Valve installed to separate inside/outside of PCV- AWJ (Abrasive Water Jet) : Processing machine that mixes abrasives with high-pressure
water to improve cutting performance(8) Storage to shipping containers from fuel debris retrieval equipment,
and dose measurement(4) Removal of deposits in the penetration X-6(9) Acceptance into glovebox and measurement

Remove deposits and cables in the penetration X-6⚫ 【Low/High pressure
water】to push deposits●Accept into a glovebox
with negative pressure
inside●Weighing and storing incontainers in a glovebox

Law/high pressure water
Penetration X-6
Entrance side

Deposits⚫ 【AWJ】to remove cable
Glovebox
Push-in device<Appearance of a glovebox>

Cable removal with AWJ⚫ 【Push-in device】
to push-in cables(10) Removal of containers, storage in shipping containers, and carry-out●Remove the container with a plastic bag to prevent
contamination from spreading●Stored in off-site transport cask and loaded ontotransport vehicles(5) Robot arm installation
Isolationvalve

Off-site transport cask ＊Plastic bag

Robot arm

Transport to transport vehicles*: Measure the surface dose and contamination density of the transported materials prior totransport and confirm that they are below the legal standard value(11) Off-site transport/off-site analysis (analysis of fuel debris properties)(TEPCO material edited by NDF)

Fig. 7 Work steps of trial retrieval (internal investigations and fuel debris sampling)
The key technical issues, countermeasures, and points to consider are described below.
・ Dust dispersion prevention associated with removal of deposits in the penetration X-6.
In light of a dust dispersion event caused by an abrasive water jet (hereinafter referred to as“AWJ”) to construct access routes for PCV internal investigation in Unit 1, measures such as
removal of deposits by low-pressure water cleaning, and dispersion control by spray curtains havebeen prepared to prevent dust dispersion due to removal of deposits inside the penetration X-6. It
is confirmed that due consideration has been given to safety measures in the operation procedures(e.g., prior understanding of dust behavior by test injection, segmentation of cutting work), whichtake measures to control dust dispersion into account, such as monitoring dust concentration andgradually expanding operations. While placing the highest priority on ensuring safety, discussions
will be held with TEPCO on setting an appropriate operational value for dust concentration control
that will not significantly extend the process due to operation constraints.

29

・ Considerations for the risk of re-spreading impact of the COVID-19 infection
For the performance confirmation test in Naraha Center for Remote Control Technology
Development, it is essential to support by the UK engineers, and it is necessary to maintain the
backup system on the UK side in the event of a defect, while sharing information andcommunicating smoothly with the UK engineers.
It is also important to make all possible preparations for the risk of the COVID-19 pandemic reexpanding in Japan. NDF will confirm these responses.
・ Considerations in project management
It is important to proceed with the project while paying attention to the process progress
management of the contractors including overseas enterprises and subcontractors. As part of theirproject management activities, TEPCO needs to make further efforts to perform prior-evaluation ofrisk of delays, and develop alternative plans and measures to prevent the occurrence of risks. NDF
also participates in meetings with contractors and their subcontractors to closely check the status
and support risk assessment.
・ Limitations in the scope of trial retrieval (internal investigation and fuel debris sampling) andincorporation into gradual expansion of the retrieval scale
In the PCV internal investigation using a robot arm, it is planned to ascertain the state of existing
structures, and the distribution of deposits inside the pedestal (3D data), the distribution of gamma
rays and neutron counts at the bottom and on the platform, in as wide a range as possible. However,since more structures and platforms in the pedestal remained than the initial design plan, the range
in which the robot-arm can access the bottom of the pedestal is limited. Thus, the possible rangeof neutron measurement and trial retrieval from the bottom of the pedestal is limited.
Incorporating the results of the arm/tool combinational test in Naraha Center for Remote Control
Technology Development, the scope and type of data to be acquired by neutron sensors, 3D
scanners, gamma sensors, etc., and the evaluation method of the conditions inside reactor (e.g.,fuel debris distribution) based on such data are planned and prepared in advance.
Assuming that fuel debris at the bottom of the pedestal cannot be retrieved, it is also planned toretrieve the deposits on the platform which are highly likely to be fuel debris, as same as those at
the bottom of the pedestal. Given the limited scope of investigation and trial retrieval, greater
consideration is required in advance to determine what information is needed to gradually expand
the retrieval scale as a next step for promoting the retrieval work in a reliable manner.
・ Human resource development and technology transfer for the next step (gradual expansion of
the retrieval scale)With regard to the trial retrieval, there are uncertainties and difficulties in the development of therobot arms and the removal of deposits and obstacles due to a limited understanding of theconditions inside the PCV. Therefore, when performing such work, it is necessary for TEPCO andparties concerned to utilize human resources with a wealth of field experience, including those30invited from outside as needed, to develop human resources to foster field-oriented
perspectives/feelings, and to transfer techniques cultivated through these activities.
3.1.2.3 Development status of gradual expansion of fuel debris retrieval and further
prospects
The retrieval equipment to be used for gradual expansion of the retrieval scale will be improvedby increasing the payload capacity and enhancing accessibility while complying with specificationsof the devices for trial retrieval (internal investigations and fuel debris sampling).
From the perspectives of research/development and engineering by TEPCO, and in terms of
ensuring actual site applicability and safety, NDF continues to observe and check the status oftechnology development and preparations for application to the site in a timely manner.
The key technical issues and countermeasures are described below.
・ Ensuring containment performance of enclosure for fuel debris
In the retrieval operation, the process is repeated from carrying fuel debris retrieved from the PCV
into the enclosure, storing in unit cans and carrying out to the outside of the enclosure for on-sitetransportation. As a result, the enclosure gradually becomes contaminated, and it is important tosecure the containment performance of the enclosure.
This work is performed by controlling the pressure in the enclosure as the robot arm is moved
in/out. Therefore, in order to confirm airtightness performance and operation reliability, through theduration, it is important to perform prior mockup test, post-installation test of the equipment, andsubsequent abnormality monitoring.
・ Ensuring reliability of a manipulator
The manipulator to be installed in the enclosure plays an important role in performing various
operations and maintenance in the enclosure, and thus it is important to ensure its reliability.
Therefore, it is necessary to improve the reproducibility of work through a wide range of
operation/maintenance training in advance, and to train operators.
・ Ensuring maintenance of devices and countermeasures during the in-service period
To expand the retrieval scale in a gradual manner, in addition to periodic maintenance, repair
or replacement is required in case of failure. Since the radiation dose in the Unit 2 reactor building,where the enclosure will be installed, is high and it is difficult to perform maintenance in that place.
Therefore, it is planned to construct a maintenance building outside the building, transfer theequipment or enclosure itself, and decontaminate, dismantle, repair or replace it inside themaintenance building. In addition, since the manipulator that performs various operations may
require repair or replacement during the in-service period, a device for carrying out the manipulator
to the maintenance building is under development.
Since it is extremely important to ensure the maintenance of equipment/devices and theirmeasures, including repairs, NDF will check the examination and preparation status for them in

31

TEPCO. It is also important to leverage the experience gained through the in-service maintenanceof equipment/devices for further expansion of the retrieval scale in scale. Therefore, a system thatcan reliably preserve maintenance records, including failure histories and their measures, shouldbe established.
・ Points of attention in detailed design, manufacturing, and installation of temporary storage
facilities
The basic and detailed design of the temporary storage facilities is being undertaken by several
companies. Furthermore, installation requires process adjustments, including eliminatinginterference with the existing systems in advance and avoiding congestion with other operations.
In installation work, construction work and equipment installation, including cells, may be
conducted almost simultaneously. Thus, design and installation involve a great deal of interfacing,
and TEPCO is expected to perform project management by managing processes and resolving
pending issues. Even though construction management for designing, manufacturing, andinstalling these temporary storage facilities is small in scale, many companies are involved, and itis necessary to proceed with construction according to the schedule while adjusting thespecifications and interfacing. We believe the experience and knowledge gained from thisconstruction work will be helpful in project and construction management for further expansion offuel debris retrieval in scale in the future. Even though a wide range of problems might occur, it isimportant to keep records of them, including their solutions, and leverage the experience insubsequent work.
The plan is to use manipulators and remote devices for operations in receiving/delivery cells
and temporary storage cells. It is important to thoroughly check the work details using thesedevices at the design stage, identify potential risks, and examine and implement countermeasuresagainst them. It is also essential to verify the design and perform mock-up test/training by referringto the knowledge and experience of remote devices in the preceding PCV internal investigationand trial retrieval.
3.1.2.4 Further expansion of fuel debris retrieval in scale
Toward further expansion of fuel debris retrieval in scale, methods should be examined basedon the viewpoint that “fuel debris retrieval is an important process in decommissioning, and its
retrieval in a reliable manner affects the success/failure of the decommissioning project,” and froma comprehensive standpoint (in anticipation of technical feasibility as well as business continuity).
In addition, TEPCO should take responsibility for examining the methods to be used. Therefore,
this section describes in detail the procedure for developing methods.
At the Fukushima Daiichi NPS, where uncertainty still exists, the uncertainty of the condition
inside the PCV hinders examination, which forces preconditions to be set to perform examination.
In judging technical feasibility in the future, it is important to clarify and examine the requirements32

(boundary conditions) and constraints (site use area, existing system interface, etc.) for methods
and systems, including criticality control, dust containment, shielding, and heat removal.
TEPCO is currently conducting a conceptual study on further expansion of fuel debris retrieval
in scale, starting with Unit 3, and examining scenarios and methods for fuel debris retrieval. In thisprocess, retrieval methods were examined by the end of FY 2021. However, many challenging
issues and risks have been identified for each discussed method. Therefore, from FY 2022 onward,
the actual site applicability and technical feasibility associated with these issues and risks will beverified. Since there may be cases resulting from the above verification where the predetermined
criteria cannot be satisfied, other methods should also be considered.
The following are the points to be considered for examining retrieval scenarios and methods.
・ Development of retrieval scenarios
In examining methods, based on the five guiding principles (safe, proven, efficient, timely, andfield-oriented), a determination should be made not only to satisfy the target safety level but also
to use attributes (evaluation items) such as cost and schedule as decision indexes. At the initialstage of the study, it is necessary to quantify these evaluation items as much as possible using
multi-attribute decision analysis (hereinafter referred to as “MADA evaluation”) and other methods,
and it is most important to clarify decision indexes and criteria. Setting these evaluation items
requires clarifying in advance information (e.g., exposure assessment report, strength calculation
report) for objectively determining whether the criteria are met. As for the results of examining themethods, it is also important to make efforts to disseminate information in a careful manner so thatthe evaluation results will be widely accepted by society.
Given the limited understanding of the situation in the PCV, it is important to examine several
scenarios of fuel debris retrieval by each unit and to clarify several paths from start to completion.
The intention of this study on fuel debris retrieval scenarios is to estimate in advance different
results obtained from PCV/RPV internal investigations or technical studies in the future and thenconduct an examination based on the preconditions of using such results.
After reviewing these numerous paths, it is important to narrow down promising candidates for
retrieval methods at a certain point of the path, and then further narrow down the path to takeaccording to the information obtained afterward.
・ Clarification of requirements
With regard to further expansion of fuel debris retrieval in scale, the methods will be considered,including those for containment, transfer, and storage of fuel debris, based on the findings from fueldebris retrieval in Unit 2 (trial retrieval, gradual expansion of fuel debris retrieval), PCV/RPV internal
investigation, research and development and the on-site environment improvement, etc. In doingso, operations, devices and equipment, and facilities will be larger than, and the scope of
construction will be wider than in the case of retrieving fuel debris from Unit 2. Therefore, much
more attention should be paid in overviewing the entire Fukushima Daiichi NPS, including other33

work. In addition, in light of the high radiation dose on-site, the limited understanding of the situation
inside the PCVs, and the extensive scope of work, it is important to specify the requirements(containment, criticality, operability, maintainability, throughput, etc.) required for operations anddevices even more clearly and proceed with the work. Attention should also be paid to theinteraction between the requirements.
The following describes the status of TEPCO's examination on the methods and NDF's view on
the matter.
・ Specific procedure and approach for examining retrieval methods
Followings are the works implemented in FY2021. In examining methods, the work process wasroughly divided into two processes, the retrieval process, and the transfer/storage process. The
retrieval process was further divided into preparation work and work inside the PCV. The
transfer/storage process was divided into work outside the PCV and transfer/storage work. Thismeans there were four major work phases, Phase 1 to Phase 4 (See Fig. 8). To examine methods
by work phase, the potential methods for each work phase was identified exhaustively, not rulingout any possibilities (setting a longlist), and then methods with low rationality was screened out(organizing a shortlist). Next, each of the shortlisted methods was scored by MADA evaluation. The
basic specifications and conditions of these discussed methods were tentatively established to
examine methods by incorporating the development results of The Project of Decommissioning,
Contaminated Water and Treated Water Management, TEPCO's engineering output, and technicalknowledge in Japan and overseas, and then issues and risks were identified and summarized (SeeFig. 9). In parallel with TEPCO's examination of methods, NDF is also independently examining
them, and TEPCO and NDF are mutually confirming their approach to the examination results andexchanging opinions.

(TEPCO material edited by NDF)

Fig. 8 Conceptual diagram of each work phase (a division of process)34• Development results of the Project of Decommissioning
and Contaminated/Treated Water Management• TEPCO’s engineering output• Technical knowledge in Japan and overseas

Longlist

Shortlist

Examinationof methods

Identify potential
methodexhaustively

Screen out
methods with low
rationality

ExamineMADA
evaluation

Partial submersion
method (example)
Submersion
method (example)

Issues andrisks in eachmethodTentatively establish
basic specifications andconditions, examine
methods

Identify/organize
issues and risks(TEPCO material edited by NDF)

Fig. 9 Examination flow for retrieval methods in FY 2021 (outline)
・ Status of examining retrieval methods[Retrieval process (preparatory work, work inside the PCV)]In the retrieval process, methods are classified according to the work environment, accessdirection, and primary boundary. The partial submersion and submersion methods were on thediscussion table. This partial submersion method does not use the top or side access method
alone but combines them, which has been examined previously. (See Fig. 10 for a conceptual
drawing of the current partial submersion method)
On the other hand, the current submersion method differs from the conventional concept ofsubmersion, as shown below. Although the conventional submersion method (fill the PCV withwater: PCV submersion method) had advantages in the radiation shielding effect, it wasdetermined to have low feasibility given the technical difficulty of sealing the water in the upper
part of the PCV and the radiation exposure during work (see Fig. 11 for the conceptual drawingof the conventional submersion method (PCV submersion method)). For this reason, the previous
retrieval policy in Mid-and-Long-term Roadmaps 2017 and 2019 focused on the partial
submersion method and it was planned to examine the submersion method again sometime in
the future based on R&D progress. Unlike the PCV submersion method mentioned above, thissubmersion method uses a new idea to submerge the reactor building by enclosing the entire
reactor building with a new structure called a shell structure2 as a boundary. (See Fig. 12 for aconceptual drawing of the current submersion method (shell method))2

Shell structure: A shell structure is a structure in which stiffener (a framework that holds deflection) supports theforce applied by the plate (surface) and it is used in ships and airplanes.

35◆Common to Figures 10 to 12
Access direction of
the devices
Transfer direction of fueldebris and radioactive waste

Fig. 10 An example of partial submersion methods(Conceptual drawing of combination of top and side access)Fig. 12 An example of submersion methods
Fig. 11 Reference : Conventional(Conceptual drawing of shell method)
submersion method(Conceptual drawing of the PCV submersion method)
Since then, the partial submersion and submersion (shell method) methods have been examined.
However, both methods have no proven track record in the nuclear industry, and many challenging
issues and risks have been identified.
Since FY 2022, the feasibility of each method will be examined. Since there are several possible
countermeasures against issues and risks, the options will be narrowed down step by step while
proceeding with the design once the feasibility has been confirmed to some extent. In addition, holdpoints should be established to evaluate on-site applicability, technological feasibility, and business
continuity such as cost and construction schedule. If the criteria are not satisfied, it is necessary toconsider ① or ② below. As described above, other methods should also be considered (See Fig.
13).
①

Reconsider measures to address issues and risks without changing the method.

②

Start over from the identification of issues and risks of other methods.

36【Perspectives at HP】
・Evaluate on-site applicability and technical feasibility
・Evaluate including business continuity

Hold points (HP)・・・

Since FY2022

Feasibility verification phase⇒Verify feasibility to address
issues and risks (multiple)

Narrow downoptions stepby step while proceedingwith the design

Design Phase
Manufacture/
installation Phase

HP: Criteria not satisfied
HP: Criteria not satisfied (consider ① or ②)① Reconsider measures to address issues and risks without changing the method② Start over from the identification of issues and risks of other methods

Fuel debris retrieval in Unit 2 (trial retrieval and gradual expansion of fuel debris retrieval), PCV/RPV internal investigation,
research and development and the on-site environment improvement, etc.

(TEPCO material edited by NDF)

Fig. 13 Conceptual diagram of how to proceed with examining methods after FY 2022
[Transfer and storage process (work outside the PCV, transfer and storage)]
For the transfer and storage process, the methods are classified according to fuel debris
processing, fuel debris/waste separation, container, hydrogen management, storage shielding,etc. Each option was evaluated as having no significant difference in terms of feasibility.
Since FY 2022, giving priority to the study of the retrieval process, examinations have been
made in terms of connectivity with the transfer process.
・ Toward initiatives for FY 2022 and beyond
As described above, from FY 2022 onward, it is necessary to systematically verify the on-site
applicability and technical feasibility to address the issues and risks. Therefore, it is necessary topromptly establish engineering planning for this study and reliably promote management,
including checking and reviewing output. To promote this, it is necessary to secure sufficient
TEPCO personnel and proceed with the study under a robust TEPCO project framework. In
addition, since there are many items to be considered, it is essential to prioritize the issues with ahigh impact on the feasibility of the method, perform checks and share information at hold points
with responsible personnel in each area (e.g., safety/radiation exposure dose, structure (seismic),
retrieval method, system, criticality, waste). For this purpose, the TEPCO/NDF review structureneeds to be clarified and further strengthened. Moreover, in examining methods, not only technicalfeasibility but also business continuity, such as cost and construction schedule, should be taken
into account from a comprehensive perspective.
Issues in each technical field for further expansion of fuel debris retrieval in scale are describedin 3.1.2.6.

37

3.1.2.5 Continuation of accident analysis activities (clarification of events that occurred at
the accident and the process of accident progression)
Analysis of deposit samples collected by the previous internal investigation for fuel debris
retrieval is in progress. The information obtained by such investigation and analysis is directly
incorporated into fuel debris retrieval methods and storage management. Moreover, examinationand study in light of the accident history will promote understanding of phenomena, contribute to
studying the cause of the accident and decommissioning, and indirectly to the improvement of
nuclear safety.
TEPCO and the JAEA are cooperating in implementing activities for estimating and verifying
individual events that occurred at the accident, including overheating, melting, chemical reactions
and hydrogen explosions, the process of their progression over time, the operation status of
emergency cooling, depressurization equipment, and the amount of combustible gases generated
from cables, etc., by comparing the results of sample analyses with mock-up testing on accident
progression and past scientific knowledge. Moreover, TEPCO is carrying out independent
investigations of the operating floor, and standby gas treatment system, (hereinafter referred to as"SGTS") and so forth in each unit.
The Secretariat of the Nuclear Regulation Authority (NRA), which is responsible for continuing
accident investigations/analyses, established the “The Study Committee on Accident Analysis of
the Fukushima Daiichi Nuclear Power Station” to discuss accident analyses and investigate theoperating floor in Unit 2, the inside of the reactor building in Unit 3, and SGTS filter trains, etc., withcooperation from TEPCO according to the situation, and compiled these results in an interim report.
Based on these investigations, the NRA has assessed that a large amount of Cs exists between
the first and second layers of the shield plug installed on the operating floor in Units 2 and 3.
Additional dose measurements in the holes bored in the shield plug of Unit 2 and geometry
measurements for deformation of the shield plug were also made.
In addition, the information necessary for accident analyses is affected by decommissioning
work, such as facility dismantlement. At the same time, there may be cases where efforts for
accident analyses interfere with decommissioning work and other operations. As such, the NRA
established the Liaison Council on accident investigation of Fukushima Daiichi Nuclear Power
Station, for communication and coordination of accident analyses and decommissioning between
the NRA, Agency for Natural Resources and Energy, TEPCO, and NDF. An example of managing
both decommissioning work and accident investigation, in the partial removal of SGTS piping in
Unit 1 and Unit 2, TEPCO is planning to take measurements of the radiation dose rates and with agamma cameras, and to collect piping samples for analysis after cutting. As a countermeasureagainst releasing radioactive dust during cutting, injection of urethane foam started in September
2021 to improve the cutting process by checking the injection point of urethane foam with a camera
and a laser pointer. Care is being taken to ensure that decommissioning work and accident
investigations do not affect neighborhood residents or the environment.

38

In addition to accident investigation activities in Japan, as an international forum on accident
progress and fuel debris analysis, projects of the Organization for Economic Cooperation andDevelopment/Atomic Energy Agency (hereinafter referred to as "OECD/NEA.”) have been
implemented since 2012. Following BSAF and BSAF-2, the FACE project, which integrates
PreADES and ARC-F, was launched in July 2022. 23 organizations from 12 countries are
participating in this project, and details are described in Chapter 4.
TEPCO is also planning to systematically conduct on-site investigation while estimating the stateof the reactor cores and PCVs, and discussing unsolved issues. After a lapse of about 11 years
since the accident, the radiation dose has decreased due to the decay of fission products(hereinafter referred to as "FP") and environmental improvements on site, and accessibility to thereactor buildings has improved. However, there are still many places with high radiation doses. In
order to locate FP released at the accident with a low radiation exposure dose, it is important tocollaborate with each organization, and continue these activities to a reasonable extent to clarify
the events that occurred at the accident, the process of their progression and the equipment
operation status. When new facts about the accident are revealed through further investigations
and other activities, it is also important to deepen and incorporate knowledge by performing severe
accident progression analysis evaluations, etc.
Since the shield plugs are installed on the operating floor, trial retrieval (internal investigationand fuel debris sampling) and gradual expansion of fuel debris retrieval, which is accessed fromthe first floor of the reactor building, are not directly affected by this. In order to further expand theretrieval scale, however, it is important to examine retrieval methods with decontamination,
shielding, and containment in mind, taking into account the possibility that access from theoperating floor (top-access) is required with full understanding of high radiation doses on the shieldplugs.
3.1.2.6 Technical issues for technical requirements and future plans
The current status and issues of the following items are described below.
(The following is a description of the partial submersion method. Although the submersion method(shell method) was identified as one of the retrieval methods taken up for discussion in section
3.1.2.4, the remaining issues shall be summarized, and a plan for future technological development
shall be developed in the process of the feasibility verification of the method against the issues andrisks after FY 2022.)
3.1.2.6.1 Technical issues for ensuring safety of fuel debris retrieval work
As for fuel debris retrieval, there are significant uncertainties (unsealed and atypical) in theconditions of fuel debris and containment barriers, and there are safety features such as handlinglarge amounts of fuel debris in incomplete containment. It is necessary to organize an approach toensuring safety based on these features and to share it with the parties concerned.

39

Currently, NDF is organizing an approach to ensuring safety with the following as the basis: ①
optimization of judgement with safety assessment as its basis ② ensuring timeliness indecommissioning activities ③ complementing design by operating controls, monitoring, analysis,
and on-site operation in the event of an abnormality. In addition, along with organizing the concept
for ensuring safety, technical requirements have been established for ensuring safety of fuel debris
retrieval and intensive studies are being conducted.
3.1.2.6.1.1 Issues in containment functions (gas-phase)
We expect that existing safety systems will be able to cope with the retrieval of fuel debris, suchas gripping and sucking, in the case of a trial retrieval or gradual expansion of fuel debris retrieval.
The AWJ used to remove obstacles during the PCV internal investigation in Unit 1 caused anincrease in dust concentration. Going forward, it is necessary to roll out this experience to similar
operations so that they can proceed carefully on a step-by-step basis while the dust concentrationis checked. In the subsequent work such as fuel debris cutting, it is necessary to construct thecontainment function of the gas phase system in consideration of re-scattering of Cs, etc., thatadhere to the equipment and structures in the PCV, aerosolization of water containing radioactive
materials, and generation of short-lived iodine and noble gases if criticality should occur.
In addition to re-scattering of Cs, etc., the fact that dispersed fine particles (α-dust) containing
α-nuclides may be generated and the radioactivity concentration in the PCV gas-phase may
increase is a concern. Therefore, dispersion of α-dust from inside the PCV must be suppressed asmuch as possible, and a function for containing the gas-phases should be provided to make theradiation dose impact on workers and the public fall within the allowable value.
Accordingly, it is reasonable to expand the retrieval scale while understanding the tendency of
dust dispersion at each stage of expanding the fuel debris retrieval scale, and verifying theappropriateness of the containment function built in the subsequent stage. In the engineering work
conducted by TEPCO, the improvement of dust monitoring installations inside the reactor buildings
and the study of decreased or negative pressure in the PCVs using existing equipment are in
progress based on the outcome of The Project of Decommissioning, Contaminated Water andTreated Water Management. In the future, the effect on the surroundings will be assessed basedon the monitoring results of the changes in condition such as the dispersion of α-dust associatedwith the work, and the retrieval scale of fuel debris will be gradually expanded. In the process,
TEPCO is considering establishing a secondary containment function and studying its necessity
through their engineering work, while assuming the possibility of an increasing impact on thesurroundings.
3.1.2.6.1.2 Issues in containment functions (liquid-phase)
To mitigate the dispersion rate of generated α-dust and to minimize the transition to the gas
phase, fuel debris cutting, etc., would be performed by pouring water over the fuel debris for fueldebris retrieval. Existing safety systems are expected to be capable of fuel debris retrieval by40

gripping and suction. For the subsequent work such as fuel debris fabrication and removal of
obstacles, a large amount of α-particles will flow into cooling water (liquid phase). To prevent thecooling water containing α-particles from leaking into the environment, it is necessary to establish
a cooling water circulation/purification system and a liquid-phase containment function inconsideration of prevention of the spread of contamination.
For this reason, it is necessary to examine technologies for removing soluble nuclides that may
be leached from fuel debris to the circulating cooling water as well as treatment technologies forsolid matter trapped by the filter equipped in the circulating cooling water system. Accordingly, The
Project of Decommissioning, Contaminated Water and Treated Water Management has beenpromoting research and development. In parallel with this, the establishment of a PCV circulating
cooling system that takes water from the PCV and injects it into the reactor for cooling, which isbeneficial in terms of preventing the spread of cooling water containing α particles, was considered
in research and development by the same Project.
To establish a reasonable containment function of liquid-phase in each stage of the scale
expansion of fuel debris retrieval, it is rational to monitor the radioactive concentration of coolingwater by stage and verify the validity of the containment function to be built in the subsequent stage
based on the results (information on fuel debris properties, etc.) obtained from research anddevelopment by the Project of Decommissioning and Contaminated Water Management. As withthe containment function (gas phase), from the viewpoint of verifying/investigating the impact of theretrieval work on the liquid phase, TEPCO, through engineering work, has been discussing system
addition/installation, etc., for the purpose of monitoring the circulating water system according to
the results of the Project. With regard to the effects on the liquid phase during fuel debris retrieval
operations, the scale of fuel debris retrieval will be expanded gradually, based on the results ofmonitoring changes in the state of waste liquid containing α-nuclides. The water level in the reactor
building is required to be maintained lower than the groundwater level to prevent the outleak ofcooling water to groundwater and to appropriately control the water level in the PCV. Safetysystems are to be established taking this into consideration.
3.1.2.6.1.3 Issues in cooling functions
Fuel debris generates decay heat, for example in Unit 2, the maximum heat generation is still
estimated to be several tens kW. The temperature is being maintained below 100°C (cold shutdown
state) currently by conducting circulating cooling with water injection into the reactor. In maintaining
this cooling function, the technical issues to be addressed for the time being include setting of thetarget temperature inside the PCV to make each task feasible, as well as the countermeasures tobe taken under the assumption of cooling function abnormalities when each task is performed.
While essential countermeasures would be to continue cooling by early recovery of the coolingwater circulation system or by mobile equipment, etc., it is necessary to evaluate changes in the
PCV internal condition based on the time margin in an emergency and to consider emergency
response measures and procedures, etc., including collection of devices. In FY 2019, water41

injection

into

the

reactorwas

temporarilysuspended

with

the

aim

of

optimizing

operation/maintenance management of cooling systems and emergency response procedures, etc.
In light of these water injection shutdown tests, from FY 2020 onward, testing will be planned andperformed depending on the purpose, taking into account the situation of each unit, fordecommissioning in the future. Based on this policy, the amount of water injection in Units 2 and 3
was decreased from 3.0 m3/h to 1.7 m3/h in tests performed in FY 2021 (Unit 2: January to March
2022, Unit 3: November 2021 to January 2022) to gradually lower the amount of water injection. In
Unit 3, the amount of water injection was increased to 2.1 to 2.2 m3/h since late June 2022 because
the water level continued to drop after the earthquake that occurred on March 16, 2022. Thus, theamount of water injected into the plant may change depending on future conditions. Based on thecondition of lowering the PCV water level, the study is underway to determine water injection
methods for the future, including further reduction of water injection.
In addition, during fuel debris retrieval operation, the processing of cutting fuel debris while
spraying water is conceivable from the perspective of dust dispersion control, and attention should
also be paid to water level control inside the PCV, as well as controlling of the contaminated water
generated.
From the above, monitoring parameters and their criterion need to be studied and preparedthrough engineering work in TEPCO in order to carefully promote fuel debris retrieval work whileobserving how this work will affect the existing circulating water cooling and purification system, as
well as its cooling function.
3.1.2.6.1.4 Issues in criticality control
Currently, subcriticality state monitoring based on the implementation plan confirms that no signsof criticality have been observed. In addition, it is assumed that impurities such as in-core structures
were introduced during core meltdown caused by melted fuel assemblies. It is estimated that fueldebris were dispersed over a wide area outside the core due to the progress of the accident.
Therefore, the criticality of the fuel debris at the Fukushima Daiichi NPS is not likely from anengineering perspective. Even assuming that control rods may melt down before the fuel elementsin the course of core meltdown and that the optimum mixing of incidentally crushed fuel debris withwater occurs, the possibility of criticality is considered small.
Although the possibility of criticality is considered low, fuel debris retrieval involves an operationthat changes the shape of the fuel debris. It is important to plan criticality control based on the
shape of the fuel debris, working conditions, and other factors and to establish a reliable control
method through prompt detection and shutdown in the case of an unexpected criticality.
In the initial stage of fuel debris retrieval, criticality control is implemented by retrieving fuel debris
while limiting the amount of fabrication based on methods that will not significantly change the fueldebris shape, such as gripping and sucking. Also, in the process of expanding the retrieval scaleand cutting, measures such as neutron measurement, pre-work subcriticality measurement, andpreparation for inserting neutron absorbers will be taken. Reliable criticality control (criticality42monitoring) is required that combines design and monitoring by operators with the decision-making
process to suspend and resume work.
The retrieved fuel debris will be placed in containers that can maintain a subcritical state and be
appropriately stored. In TEPCO’s engineering work, the concept design is in progress for circulatingwater system configurations and system specifications for further expansion of fuel debris retrieval
in scale.
3.1.2.6.1.5 Issues in the structural integrity of PCVs and buildings, etc.
As for the main equipment in the PCV/RPV pedestal, etc., and reactor buildings, their structural
integrity has been evaluated in post-accident studies by TEPCO and the Project ofDecommissioning and Contaminated Water Management. As a result, it has been confirmed thatthe main equipment and reactor buildings have a certain level of seismic margin.
Hereafter, the existing main equipment and reactor buildings, as well as equipment/systems andbuildings (including modified areas of the existing equipment/systems and buildings) to be newly
installed for fuel debris retrieval over a relatively long period, should satisfy the functional
requirements and (1) be capable of performing operations safely and (2) ensure the required levelof safety against external events such as earthquakes and tsunamis. Assuming (3) long-term
maintenance management, in addition, it is important to (4) feedback new knowledge to be gained
from planned PCV internal investigations and fuel debris analysis results, etc., to the design of fueldebris retrieval systems and the study of retrieval methods.
Moreover, regarding the existing equipment/systems and buildings, lowering of the water levelin the PCVs of Units 1 and 3 was confirmed after the earthquakes that struck off the coast of
Fukushima Prefecture on February 13, 2021, and March 16, 2022. Although cooling functions weremaintained in both earthquakes, in light of both earthquakes, in order to maintain and manage theequipment/systems and buildings with the above functions over the medium-and-long term, it isnecessary to conduct impact assessments on the accident impact, aging degradation and external
events (earthquakes and tsunamis, etc.) anticipated during the decommissioning period. In view ofthe fact that the past assessment of these effects was limited, it is necessary to make maximum
use of existing techniques and evaluation results for planning and implementing an investigation
plan, in which remote control under a high radiation environment is a challenging issue, and todevelop underlying technologies to understand the situation. In so doing, while giving priority tosafety, it is useful to actively introduce the latest knowledge and achievements not only in the
nuclear field but also in other fields. Based on the above impact assessment, it is crucial to prepare
for these risks caused by earthquakes or aging degradation expected hereafter. The following
discusses preparedness for seismic risk and aging degradation risk.
(1) Seismic risk preparedness
To prepare for possible seismic risks in the future, it is important to specify and implement
measures after determining the margin through seismic assessment. In this process, the43uncertainty in the on-site environment, the work difficulty, and the workers’ exposure should befully considered.
Seismic assessment needs to consider the impact of the accident and thinning caused by aging
degradation in line with the actual situation and set the conditions for examination. However,
because of the high-dose environment, the information available is limited, and establishingconservative conditions for examination may increase the difficulty of implementing measures.
Therefore, considering that high uncertainties result in moderately conservative conditions, it isalso important to work to understand the impact of the accident and the actual state of aging
degradation with high accuracy. For example, although the measurable areas are limited, it should
be devised to reduce uncertainties in the scope and method of feedback, etc., such as utilizing
the measurement results of the corrosion growth rate in piping for estimating locations where
measurement is not possible based on model analysis.
In addition, one method for seismic risk preparedness is reducing the stress generated during
an earthquake. For example, drainage is planned for the S/C in Units 1 and 3 with a water level
higher than during normal operation caused by the accident. In Unit 3, drainage of the main bodyof the PCV is underway, which is required before drainage of the S/C.
Regarding the reactor buildings of Units 1 to 3, a certain level of safety has been confirmed
through seismic assessments that take into account the state of damage after the accident.
However, as with the main facilities described above, verification of the seismic safety over a long
period during fuel debris retrieval is required.
For this purpose, although it is challenging to perform investigations due to the high radiationdose, continuous investigations should be carried out to observe the condition of the damage,deterioration, and condition of the corrosion.
As TEPCO undertakes the following activities, it is important to accumulate knowledge throughongoing investigations and consolidate information on the condition of the buildings.
• Application of unattended and labor-saving technologies that utilize robots and drones• Detailed surveillance by core sampling using Unit 4, where detailed assessment is practical• Installation of seismometers and utilization of observation records
When the above investigation reveals new facts or findings for components considered in theseismic assessment, such as a decline in structural performance or additional damage due to large
earthquakes, it is important to update the information on the condition of buildings and incorporate
it into the seismic assessment as appropriate.
(2) Aging degradation risk preparedness
Since thinning due to corrosion is assumed to cause degradation of RPVs and PCVs due toaging, the structural strength tends to decrease over time. Possible preparedness can be for the
structures themselves and the environment in which they are installed. Generally, measures for theformer includes coatings. However, it is extremely difficult considering humans cannot easily

44

approach the structures. Therefore, priority will be given to examining the latter environmental
approach. For reactor water injection as ongoing action, measures are being taken to reduce thedissolved oxygen concentration by nitrogen bubbling and hydrazine injection in the tanks. For thegas phase, nitrogen is sealed inside the PCVs.
However, since the PCVs are damaged, and degradation due to aging progresses over time, it
is important to implement measures to maintain the low oxygen concentration in the PCVs
appropriately and continuously.
As for existing and new equipment/systems and buildings, the loading conditions (layout, size,
weight of the new equipment/systems, new openings on PCV/biological shielding walls, etc.) during
fuel debris retrieval will be specified with further progress in designing. In order to ensure thestructural integrity of equipment/systems and buildings, while considering the state of the site,examination will be promoted steadily based on the latest design information.
3.1.2.6.1.6 Issues in reduction of radiation exposure during work
In accordance with the Mid-and-Long-term Roadmap and TEPCO's Mid-and-Long-term
Decommissioning Action Plan, removal of obstacles and radiation dose reduction in the reactor
buildings are in progress as improvement of the work environment in work areas/access routes. In
preparation for trial retrieval, ongoing on-site radiation dose reduction has resulted in reducing theradiation dose around the aisle on the west side of the first floor of the Unit 2 reactor building andthe penetration X-6 in the northwest area to approximately 5 mSv/h or less (average 2 to 3 mSv/h).
In the future, as work related to fuel debris retrieval, reduction of exposure during work such as
removal of high-radiation dose equipment, etc. is an issue, and research and development has
been promoted by The Project of Decommissioning, Contaminated Water and Treated Water
Management to support TEPCO’s engineering.
The main work areas related to fuel debris retrieval are high radiation dose areas such as inside
the reactor buildings. Also, there comes the need to handle nuclear fuel materials containing αnuclides from fuel debris with a large dose contribution in the case of internal exposure. Accordingly,
enhanced control of not only for external exposure but also for internal exposure is essential for
reduction of exposure.
With the objective of dose reduction in long-term decommissioning, it is important to accumulateknowledge such as on-site operation experiences and lessons learned and hand down know-how.
For further expansion of fuel debris retrieval in scale, it is necessary to share information such as
the technique of handling α-nuclides during trial retrieval and allow prompt feedback for the next
work plan. Since May 2021, JAEA, which has the knowhow, has been providing guidance inpreparation for trial retrieval due to concerns about body contamination and internal exposure risks
in handling α-nuclides.
In particular, in fuel debris retrieval operation, access to the PCV should be made from thepenetration X-6, etc., after the work environment in the reactor building is sufficiently secured. To
45reduce the radiation exposure of workers in the reactor building, it is important to conduct sufficientinvestigations on the radiation dose distribution and state of contamination, including thecontribution from the surroundings of the subject areas, to identify the source locations and intensity
as much as possible and to build the radiation dose reduction plan. Upon adequate verification on
the operation feasibility, the target dose rate in the work areas and access routes shall be set inconsideration of the margin for the radiation exposure dose limit for workers specified by laws andregulations. In the radiation dose reduction plan for high radiation dose areas, it is important to takemanagement measures to reduce the total radiation exposure dose to as low as reasonably
achievable and accomplish operations with respect to work hours in accordance with dose limits
and required work hours to accomplish operations. Based on the above, and as R&D tasks by The
Project of Decommissioning, Contaminated Water and Treated Water Management, thedevelopment of technologies to identify radiation sources using environmental survey data and todigitize the environment and radiation source distribution visualized by digital technology, for theformulation of safe and efficient work plan has been in progress since FY 2021. This has led to thedevelopment in accordance with the required functions. Moreover, in developing remotetechnologies for environmental improvement and removal of obstacles under high radiation dose,the obstacles to be removed have been selected and the elemental technologies have been
extracted in accordance with the required functions, and specifications of remote control device
have been studied for engineering implemented by TEPCO based on the results of technicalinvestigation and element test since FY 2020.
It is necessary to formulate a long-term work plan to help reduce the total radiation exposure ofworkers without concentrating worker exposure on specific individuals, implement holistic andadequate radiation exposure control, and secure workers as human resources from a long-term
perspective. Support should be provided to develop a database that can improve the efficiency ofwork planning and radiation exposure control and establish a system that manages and operates
various information on the entire Fukushima Daiichi NPS in an integrated, step-by-step manner.

3.1.2.6.2 Technical issues related to fuel debris retrieval methods
3.1.2.6.2.1 Issues in securing access routes
For carrying in, installing, and carrying out devices and equipment used for fuel debris retrieval
work, and transporting fuel debris and waste, access routes should be established by removing
obstacles on the access routes and reducing the radiation dose in the R/B to the level at whichsuch tasks can be performed. When establishing new openings in the PCV or the like to constructaccess routes to fuel debris, suppression of the release of radioactive materials from the PCV and
RPV and maintaining the integrity of existing structures should be kept in mind.
The Mid-and-Long-term Roadmap indicates that the first implementing unit would be Unit 2 andtrial retrieval begins toward gradual expansion of fuel debris retrieval. Accordingly, TEPCO is

46

currently proceeding with specific engineering studies to conduct an access route from penetration
X-6 in Unit 2.
On the other hand, toward further expansion of fuel debris retrieval in scale, studies areunderway on the construction of access routes from the side opening of the PCV to fuel debris (theside access method), based on the results of research and development conducted to date by The
Project of Decommissioning, Contaminated Water and Treated Water Management. In the sideaccess method, the issue is to address containment, shielding for connecting structures between
newly installed heavy structures and the side-opening of the PCV, and seismic displacement, andtechnical development of the method is underway using lightweight cells and fixed rails as well as
access tunnel systems.
As for the construction of access routes including top access (top-access method), in addition
to side access, the technology for removing obstacles and transportation methods that can shorten
the preparation processes for retrieval are under study in order to enhance throughput. Since FY
2020, the Project has been examining the feasibility of a method to cut, retrieve and transportinterfering structures as a single or large unit while ensuring containment and shielding. TEPCO’s
engineering has been studying the overall process of the methods for Unit 3, assuming that it will
be necessary to combine side-access retrieval, which provides easy access to the inside andoutside of the pedestal, and top-access retrieval, which provides easy access to the inside of the
RPV. The NRA pointed out the possibility that a large amount of Cs might exist on the undersurfaceof the shield plugs of Units 2 and 3 from their evaluation of TEPCO's radiation dose measurementson the operating floor. In this respect, consideration needs to be given to establishing access routes
for the top-access retrieval method based on the results of additional investigations in the second
half of 2021, including surveys on the situation and radiation doses in the reactor well below theshield plug and radiation dose surveys in the borehole.
In the future, based on the above-mentioned issues, it is necessary to clearly define the accessroute to be built at the next stage from the data obtained at each phase of scale expansion of
retrieval. In particular, when cutting the inner door of the penetration X-2 in unit 1, the dust
concentration in the PCV increased more than expected before the start of the work, and thepressure in the PCV dropped while installing a camera chamber for investigating obstacles.
Therefore, not only countermeasures to prevent dust dispersion, but also the extra time required
for responding to when faced with such an unexpected situation need to be considered and planned.
3.1.2.6.2.2 Issues in development of devices and equipment
In each phase of trial retrieval, gradual and further expansion of fuel debris retrieval in scale,devices and equipment for fuel debris retrieval need to be developed with emphasis on safety,
reliability, and efficiency. To flexibly respond to the situation inside the RPV and the PCV bottom
where the fuel debris is predominantly present, the specifications of devices/equipment to be
developed in these phases should be established in consideration of radiation resistance, dust
resistance, waterproofness, range of temperature, remote inspection/maintainability, remote47

operability, securing visual field, seismic resistance, protection mechanism for collision avoidanceor automatic shutdown in case of abnormality, high reliability, appropriate redundancy, a rescue
mechanism that does not disturb the subsequent work when a problem occurs, and efficiency offuel debris retrieval.
Equipment development for trial retrieval and gradual expansion of fuel debris retrieval has
progressed as part of research and development of The Project of Decommissioning,
Contaminated Water and Treated Water Management. Testing and training of the robot arm andother equipment to be applied to the trial retrieval of Unit 2, which had been underway since 2021,
has been completed at the manufacturer's plant. Testing and training are now in progress at the
Naraha Center for Remote Control Technology Development from 2022. After the gradualexpansion of fuel debris retrieval, TEPCO needs to take over and substantiate the development
results. While preparing education/training scheduled to be started from 2021 for the fuel debris
retrieval operations using these remote devices. Prior to installing remote equipment such as robot
arms on site, adequate performance verification and operation training are essential by using
mockups simulating the expected PCV internal environment. For this purpose, examination ofmockup systems has been made.
Regarding devices and equipment for further expansion of fuel debris retrieval in scale, thefollowings are underway: development of the installation methods of access systems and sideaccess retrieval methods associated with dismantling/removal techniques for interfering equipmentin the PCV, and development of top-side retrieval methods for cutting and transporting large
equipment and for preventing the spread of contamination. TEPCO is currently conducting a
conceptual study to examine methods for further expanding the scale of retrieval. In FY 2021,
TEPCO examined retrieval methods to identify issues and risks for each method. Since FY 2022,
studies have been conducted on these issues and risks in terms of feasibility. Further developmentof devices and equipment should be planned and promoted in light of the status of examination of
the methods.
As for how to proceed with development, it is necessary to flexibly promote operations in thesubsequent phase based on the information gradually obtained from preceding investigations andretrieval work, and to continue development for emerging important issues. The developed devices
and equipment need to be combined as a system and undergo a series of mockup tests todemonstrate that they can realize their performance safely and reliably at the actual site. These
mockup tests need to be implemented in a facility simulating the on-site environment in order toverify the applicability of remote equipment and operability/maintainability of the entire remotesystem under severe environmental conditions containing significant uncertainties. Therefore, in
cooperation with the organizations concerned, NDF and TEPCO have been engaged in examining
how to proceed with the remote mockup test plan, the test plan review, the scope of the mockup
facility to be maintained, the time required, and operation management, etc. From FY2021, TEPCO
has taken the initiative in promoting examination and materialization.

48

3.1.2.6.2.3 Issues in system installations and working areas
Assuming that safety functions are ensured, and considering avoidance of excessive system
specifications, it is necessary to examine the establishment of system installations, etc., takenecessary measures such as system additions based on the results of such examination, and thento operate them properly. In carrying out examination, sufficient areas should be secured to satisfy
the required environmental conditions while considering installing shields for reducing radiation
exposure for workers in addition to system installation, operation/maintenance management.
The system installations include a negative pressure control system required for establishingcontainment functions (gas phase), a circulating water cooling and purification system required formaintaining the containment functions (liquid phase) and cooling functions, and a criticality control
system required for controlling criticality. Moreover, realization of measurement systems (forpressure, temperature, water level, radiation, etc.) to monitor the PCV internal state is a significant
issue, which is essential for fuel debris retrieval. For building of safety systems incorporating theabove, prerequisites (system design criteria) are provided tentatively based on the research anddevelopment performed by The Project of Decommissioning, Contaminated Water and Treated
Water Management, and TEPCO has been examining the system design and layout through theirengineering work.
Regarding the gas-phase system, in FY 2021, the preconditions for negative pressure control
and the concept of ancillary systems were summarized with a view to the lowered airtightness of
the PCV. For the liquid-phase system in the Project, technologies to remove soluble alpha-nuclides
and treatment of secondary waste generated by water treatment are under development.
3.1.2.6.3 Technical issues related to safe and stable storage of fuel debris
3.1.2.6.3.1 Issues in handling fuel debris (containing, transferring, and storing)
Before initiating gradual expansion of fuel debris retrieval work, a comprehensive system shouldbe established that consists of a series of steps from containing and transferring to storing of
retrieved fuel debris furnished with safety functions such as maintaining subcriticality, containment
functions, countermeasures against hydrogen generation, and cooling. Accordingly, examination of
the following is being progressed until the end of FY 2021.
・ Development of basic specifications for the container, such as overall length in considerationof handling, internal diameter, quality of materials and lid structure in light of work efficiency
and maintaining subcriticality, etc., and demonstration of the structural integrity of thecontainer by testing.
・ Examination of a practical and rational prediction method of hydrogen generation from fueldebris stored in containers; determination of a vent mechanism for hydrogen gas release on
the container lid by using the said prediction method; and establishment of safe transferring
conditions with consideration for accumulation of hydrogen gas in transferring casks.
・ Development of efficient drying technology applicable to fuel debris in unit cans, andconsideration on a drying system using this technology.
49

Moreover, in reference to the results of these studies, TEPCO continues their activities tomaterialize the equipment and installations (including canister for temporary storage,
receiving/delivery cell, and storage cell) needed for containment, transfer, and storage of fuel debris,which will be retrieved during the gradual expansion of fuel debris retrieval, in coordination withother associated projects. Toward further expansion of fuel debris retrieval in scale, storage
locations have been examined based on the usage plan for the entire site, and specific transferring
routes and storing technologies/types are also under consideration. This study has focused on
granular and mass fuel debris. The pulverized fuel debris generated by fuel debris cutting in a slurryor sludge state in the cooling water circulation system as well as in powder state in the gas
management system. Therefore, in line with the progress of this study, examination is underway of
methods for safe, reliable, and rational storage of powdered and sludge/slurry fuel debris, as wellas the necessary equipment and installations, and it is necessary to progress this steadily.
At present, since the information and knowledge on the properties of fuel debris is limited, thesystems and devices/installations will be designed based on conservative assumptions of theproperties of fuel debris. In the design of equipment and facilities for containing, transferring andstoring of fuel debris for further expansion of fuel debris retrieval in scale, it is important to proceed
in a streamlined manner by utilizing various measurement data such as the amount of hydrogengeneration and debris properties as well as knowledge and experience of the handling of fuel debris
during the operations from receiving of the onsite transport container to the storage facility whichhave been collected and accumulated during the trial retrieval and gradual expansion of fuel debris
retrieval.
The Mid-and-Long-term Roadmap stipulates that the processing/disposal method of theretrieved fuel debris shall be investigated and fixed during the third phase after starting the fueldebris retrieval work.
3.1.2.6.3.2 Issues in sorting out fuel debris and radioactive waste during fuel debris retrieval
In the fuel debris retrieval work, obstacles and structures to which molten fuel are partiallyadhered will also be retrieved from the PCV in addition to fuel debris in which molten core fuel are
mixed with metals and solidified, and compounds (MCCI product) produced by mixing molten corefuel with concrete at the PCV bottom. Furthermore, pulverized fuel debris generated during fueldebris cutting is also recovered. Of these, if substances on which a small amount of molten fueladheres or is mixed are all stored as fuel debris, it may become an obstructive factor in advancing
decommissioning because the scale of facilities and sites for fuel debris storage become larger.
Since it has been determined from the fuel debris properties that special attention andinstallations/systems for handling and storing are required to maintain subcriticality, it isrecommended that fuel debris and radioactive waste be separated based on the measurement
results of the amount and concentration of nuclear materials and stored separately (sorting). The
following studies were conducted in response to this.

50

・ Consideration of which steps in the operation processes, from retrieval to storage, sorting isfeasible to separate retrieved materials from the PCV (fuel debris, structures, etc.) into fueldebris and radioactive waste (consideration of sorting scenarios).
・ Investigation of techniques/devices that may be capable of measuring or estimating theamount and concentration of nuclear materials contained in the materials retrieved from thePCV in non-destructive methods (investigation of possible measurement techniques).
Based on these studies, it is currently considered an incredibly difficult challenge of requiring
innovative technology development to measure or estimate the amount and concentration of
nuclear materials in the materials retrieved from the PCV using non-destructive methods because
various materials, including rod components (neutron absorber), are mixed inhomogeneously.
In developing measurement techniques and devices, it is important to understand themeasurement errors. Other than major factors affecting measurement errors such as the fuel debris
properties, location of nuclear fuel material in fuel debris and the storage condition of them in unitcans or containers, there are many factors affecting errors depending on the techniques/devices
itself. The extent of such impact is highly uncertain at present due to a lack of knowledge on theproperties of fuel debris. Therefore, in parallel with the accumulation of measurement data and thedevelopment of actual measurement devices by iterating actual measurement using mockup fueldebris, etc., it is considered beneficial in terms of R&D cost and time saving to identify factors
influencing measurement errors and its strength accumulated by a number of numericalexperiments by computer and incorporate the findings such as the extent of influence into thedevelopment of the actual measurement technologies/devices. Thus, the impact of various
condition of fuel debris with different properties and storage conditions on the measurement errors
as well as modifications/improvements (e.g., specifications of shielding materials and theirinstallation location) of measurement techniques/devices to reduce measurement errors can also
be examined through numerical experiments by computer. Some positive results were obtained in
the examination mainly on the numerical experiments in The Project of Decommissioning,
Contaminated Water and Treated Water Management in FY 2021. From FY 2022 onward, in
addition to the development of measurement devices based on the analytical approach mainly
through numerical experiments described above, it is important to continue and accelerate thedevelopment of measurement devices by actual measurement of mockup fuel debris and fueldebris of the Three Mile Island Nuclear Power Plant Unit 2 (hereinafter referred to as "TMI-2".) inparallel, using currently available measurement devices.
Trial retrieval and gradual expansion of fuel debris retrieval may provide knowledge on actual
fuel debris properties through limited sample analysis. Once this knowledge is obtained, it also
becomes possible to check whether the measurement results of the non-destructive measuring
devices contain significant errors.
It is important to enhance practical applicability and effectiveness of the measurement
technologies/devices by continuing the development of them in order to separate (sort) the storage
conditions of fuel debris and radioactive waste by such a method.
51

3.1.2.6.3.3 Issues in examining safeguards strategies
Material accountancy and safeguards to the retrieved fuel debris is unprecedented, TEPCO may
face technical issues in examining and applying them to the site. For this reason, NDF will conduct
wide-ranging surveys on existing technologies related to material accountancy and safeguards toprepare in case that TEPCO needs technical assistance. NDF will also check the progress of the
project from an engineering perspective to confirm that the application of safeguards to systems
has not affected the decommissioning process.
The main technical issues and plans described in this section are summarized as shown in Fig.
14.

52

Short term (recent 3 years)
Fiscal Year2022

Mid-to-Long-term (FY2025 to End of FY2033)
27
28
29
30
31
2027
2033(yr)26▽ Start of fuel debris retrieval in Unit 2* According to the Roadmap, the retrieval was supposed to start by the end of 2021, but the process waschanged to improve the work safety and certainty based on the impact of coronavirus infection,subsequent testing and site condition.

RM milestones
Trial retrieval(Internal investigation and fuel debris sampling)(Unit 2)

24
25
2024

2023

Improveenvironment
inside the building
Manufacture/ install the retrieval
deviceOn-siteoperation

Trial retrieval(internal investigations andfuel debris sampling)
Characterize the fuel debris：The period during whichchange is expected
Technical studies on individual items relating to onsite construction
R&D：To be conducted as required
Technical issues in the program on Decommissioning
and Contaminated Water Management
Basic/fundamental research

Improve environment
inside the building

Gradual expansionof fuel debris retrieval(Unit 2)

Fuel debris retrieval facility/safety system/fuel debris
temporary storage facility/maintenance facility
Design and production：Work period

Gradual expansion of fuel debris
retrievalInstallation

Characterization of fuel debris

RPVinternal investigation

Review of the program on Decommissioning and Contaminated
Water Management and TEPCO's voluntary project--PCV内部詳細調査技術の開発
Development of technology for detailed investigation inside PCV--燃料デブリの段階的に規模を拡大した
Development of technology for the gradual expansion of fueldebrisretrieval
取り出し技術の開発

Technical study by TEPCOTechnological issues for gradual expansion of fuel debris retrieval(1) Preparing retrieval system (improving durability of equipment, transfer test by transport truck)(2) Manufacturing equipment for gradual expansion of fuel debris retrieval (3) Providing storage facility of fuel debris / waste

Further expansionof fuel debris retrieval(Units 1/3)

Improvement of the environment inside and outside the Unit 1 building(Inside of the building: Dose reduction/removal of obstacles;
Outside of the building: Removal of lower part of exhaust stack of Units 1 and 2/removal of transformers, etc.)
Improvement of the environment inside and outside the Unit 3 building(Inside the building: PCV water lowering/dose reduction/removal of obstacles;
Outside the building: removal of the exhaust stack of Units 3/4, removal of transformers, etc.)
PCV internal investigation

Fuel debris retrieval facility/safety system/fuel debris storage facility/maintenance facility/training facility and others *Review on the concept, Actual siteapplicability verification,
developmentv and design

Production, installation, and retrieval

Reviews of the Program on Decommissioning and Contaminated/-原子炉建屋内・外の環境改善のための技術開発
TreatedWater Management and Basic/fundamental research
躯体・機器設備の劣化状況等の評価方法の開発- Developmentof technologies for environmental improvement of
inside and outside reactor building-放射性物質の分布を可視化し、被ばく量の低減に寄与する研究
Development of evaluation method for deterioration of building
放射線と腐食・材料劣化の関係に関する研究
frame and equipment--１号機PCV内部詳細調査技術の開発
Research to visualize the distribution of radioactive materials andcontribute to the reduaction of radiation exposure
Research on the relationship between radiation and corrosion/-RPV内部調査技術の開発／RPV内部調査の高度化
material degradation- Development of technology for detailed investigation inside Unit 1-RPV内部簡易調査技術の開発
PCV- Development of technology for investigation inside
RPV/Advancement of investigation inside RPV-燃料デブリ性状把握のための分析技術の開発- Development of technology for simplified investigation inside RPV-分析技術の実証（放射性物質分析・研究施設活用）- Development of analytical techniques for characterization of fueldebris-非破壊測定を含む取り出された燃料デブリの分析評価手法に関する研究- Demonstration of analytical techniques (analysis of radioactive
放射性物質・核燃料物質の分析技術の高度化に関する研究
material/utilizationof research facilities)--PCV内状況推定の高度化
Research on analytical evaluation methods for retrieved fueldebris, including non-destructive measurement
Research on advancement of analytical techniques for-燃料デブリの分析と解析・評価により炉内状況の推定及び事故事象に関す
radioactive/ nuclear fuel materialる研究- Advanced estimation of the state in the PCVs
-燃料デブリ・炉内構造物の取り出し規模の更なる拡大に向けた技術の開発- Research on estimation of the state inside reactor and accident
event through analysis and evaluation of fuel debris--燃料デブリ取り出し及び保管時の安全を確保に関する研究
Development of technologies toward further expansion of fueldebris/ internal structure retrieval--遠隔装置保守技術の開発
Research on ensuring safety for retrieving and storing fuel debris- Research on visualizing distribution of radioactive materials andcontributing to reduction of radiation exposure-燃料デブリ収納・移送・保管技術の開発- Development of technologies for containing, transferring andstoring fuel debris-１Ｆ廃止措置統合管理のための支援技術の開発- Research on ensuring safety for retrieving and storing fuel debris- Development of support technology for integrated management of
1F decommissioning

Technical study by TEPCOTechnical issues toward further expansion of fuel debris retrieval(1) Development of fuel debris retrieval method (Side access/top access/of common)
Development of access facility installation, dismantlement technology, technology development for realization of large piece
removal cocept, crashing and containing technology(2) Development of safety system (Liquid system/ gas system and critiality control system)
Strengthening function to remove radioactive material, development of boric acid management technology such as boric acidrecovery, evaluation of dust behavior and recovery(3) Strengthening and sofistication of containment technology
Development of containment technology for radioactive material by passive control(4) Development of safety assessment technology
Data aquisition of debris dispersion rate and analytical method for evaluating radiation exposure(5) Development of technologies for maintaining remote equipment
Development of decontamination and maintenance technology for contaminated remote equipment* It is assumed that Unit 3 will be examined in advance and expanded to Unit 1.

Fig. 14 Technical issues and future plans on fuel debris retrieval (progress schedule)

533.2 Waste management
3.2.1 Targets and progress(Targets)(1) The Solid Waste Management Plan (hereinafter referred to as the "Storage Management
Plan") is appropriately developed, revised and implemented including waste prevention,
volume reduction and monitoring, with updating the estimated amount of solid waste to begenerated in the next ten years periodically.
(2) Based on the prospects of processing/disposal methods of solid waste and technology related
to its safety (hereinafter referred to as Technical Prospects) presented in FY 2021, creation of
options for processing/disposal measures and their comparison and evaluation should be
conducted with promoting characterization to establish a waste stream that are suitable forfeatures of solid waste. Proceed study on specific management of the solid waste to present
appropriate measures as a whole.

<Key points of "Basic Policies on Solid Waste">① Thorough containment and isolation
・Thoroughly containment and isolation radioactive materials to prevent human access tothem, in order not to cause harmful radiation exposure.
② Reduction of solid waste volume
・To reduce the amount of solid waste generated by decommissioning as much as possible.
③ Promotion of characterization
・ Proper characterization addressing an increase in the number of analysis samples toproceed with studies on processing/disposal methods of solid waste.
④ Thorough storage/management
・Generated solid waste should be stored/managed safely and reasonably according to its
characteristics.
・Storage capacity should be secured to ensure that the waste can be stored within the siteof the Fukushima Daiichi NPS.
⑤ Establishment of selection system of preceding processing methods in consideration of disposal
・To establish selecting methods of processing for stabilization and immobilization (preceding
processing) and then select preceding processing methods before technical requirementsof disposal are established.
⑥ Promotion of effective R&D with an overview of overall solid waste management
・ To establish the continuous operational framework including development of relevant
facilities and human resources in order to continue safe and steady solid waste
management.
⑦ Development of continuous operational framework54

・ To establish the continuous operational framework including development of relevant
facilities and human resources in order to continue safe and steady solid waste
management.
⑧ Measures to reduce radiation exposure of workers
・Thorough implementation of radiation exposure control, health and safety management
based on the relevant laws/regulations.

(Progress)
Waste management is a long-term effort that needs to attain the prospect of implementing final
disposal, while reducing risks in every stage from generation, storage, processing to disposal.
Since a large amount of solid waste with various characteristics is generated in association withdecommissioning of the Fukushima Daiichi NPS, the efforts based on the "Basic Policies on Solid
Waste” summarized in the Mid-and-Long-term Roadmap are underway. TEPCO is required toensure safe and reasonable storage/management of the solid waste generated. Led by NDF, theorganizations concerned are promoting efforts based on each role to advance technicalexamination of integrated measures from characterization to processing/disposal of solid waste.
The Technical Prospects were provided in FY 2021 in light of the development results for improving
analysis abilities for characterization and establishing a flexible and reasonable waste stream (theflow of the integrated measures from characterization to processing/disposal). The Mid-and-Longterm Roadmap stated that the properties of solid waste would be analyzed, and the specificationsof waste form and their production methods will be determined in Phase 3. Therefore, the study
was initiated for specific management of solid waste to present appropriate measures as a whole.
The Project of Decommissioning, Contaminated Water and Treated Water Management related
to solid waste has been mainly conducted by IRID. However, in preparation for the deadline of thetermination of IRID around the summer of 2023, JAEA is taking the main role in the projects which
are started from FY 2022.
3.2.1.1 Current status of storage/management in Fukushima Daiichi NPS
To store solid waste properly, TEPCO releases its Storage Management Plan, and estimates
the volume of solid waste that will be generated in the next ten years, and shows their policy suchas on building waste management facilities to be required based on the volume.
According to this Plan, temporary outdoor storage of the solid waste will be eliminated completely
by FY 2028, except for secondary waste generated by water treatment and targets ofreuse/recycling. Facilities needed to achieve this goal are under development.
The Technical Prospects have provided the examples of overseas countries that have
implemented the waste hierarchy concept (the priorities for measures to be taken as waste
management are in the following order: (1) prevention of waste generation, (2) minimization ofwaste volume, (3) reuse, (4) recycling, and (5) disposal (Fig. 15)). In waste management, it isimportant to prioritize (1) as much as possible and consider (5) disposal as the last option, andTEPCO has also been implementing initiatives corresponding to this concept.
55

Among the targets of reuse/recycling, concrete rubble is crushed and recycled as roadbed
material after confirming that the surface dose rate is equivalent to the background radiation dose.
In addition, such as by melting is under consideration as a decontamination method for recycling
metal. The Project of Decommissioning, Contaminated Water and Treated Water Management has
also begun to clarify the nuclide distribution behavior during melting and decontamination andexamine validation methods after melting treatment as required research and development toachieve the above.
Secondary waste generated by water treatment is planned to be transferred to store in a building,with priority given to sorption apparatus that contain large amount of radioactivity, and a large waste
storage building is being constructed as a storage facility for sorption vessels. Moreover, the slurry
generated at ALPS (hereinafter referred to as "ALPS slurry") generated by the multi-nuclide
removal equipment, etc., and the waste sludge generated at the water purification system(hereinafter referred to as "waste sludge") have high water content and flowability. For safer storage,
ALPS slurry will undergo stabilization (dehydration) treatment (Scheduled installation of treatment
facility in FY 2024), while waste sludge will be collected from the underground storage tanks in thebuilding, where it is currently stored, dehydrated and then stored into containers, before beingtransferred to higher ground (starting in FY 2023).
Such solid waste will continue to be generated with some exceptions, and additional solid waste
will be generated from fuel debris retrieval.
Summary of the Waste Hierarchy

Installation of a vehicle service station,
prevention of carrying in packing material,and common use of construction equipment

Waste Prevention

Preferred
Approach

Examples of countermeasuresat the Fukushima Daiichi NPS

Waste Minimisation

Classification, segregation, etc., of waste

Re-use of Materials

Examination on re-use of metals, concrete,and dismantled pieces of flange tanks with avery low surface dose

Recycling
Application of volume reduction equipment(an incineration system, a crusher, and a
metal cutting machine)

Disposal

Source: Strategy Effective from April 2011 (print friendly version), arranged by NDF

Fig. 15 Summary of waste hierarchy at the NDA, UK, and countermeasures at the Fukushima
Daiichi NPS

3.2.1.2 Examination of processing/disposal methods
For characterization, examinations are in progress to establish a methodology for developing a
medium-to-long-term analysis strategy that defines the solid waste to be analyzed, its priority, andquantitative targets for analysis, etc. Initiatives have begun to use the results of the establishedsimplified and speed-up data acquisition for radiological analysis as standard analytical methods
at the Radioactive Material Analysis and Research Facility Building-1 (construction to be completed56

in June 2022). A field demonstration of techniques to collect sorption from cesium sorption
apparatus is in progress to obtain analytical data on high activity waste.
For storage/management, factors affecting filter degradation (blockage/damage) such ashydrogen embrittlement, radiation degradation, etc. and their verification methods were examinedand summarized to maintain vent filter functions, which are important as hydrogen generation
measures during storage of high radiation-dose waste. Issues during storage and theircountermeasures were also examined based on domestic and overseas cases associated with
events of concern other than hydrogen generation.
As for the processing technology, the prospect of the application as actual equipment of thermal
processing technology to ALPS slurry that has been confirmed through the Technical Prospects.
Further, a detailed examination was carried out to control Cs volatilization during processing. While
the prospect of the application as actual equipment of normal temperature processing technology
was confirmed through full-scale tests, issues related to the transformation of solidified waste andinspection methods for verifying the possibility of solidification are being examined. To contributeto the expansion of technological options, such as expanding the scope of application of normal
temperature processing technologies, verification of the applicability of pyrolysis treatment andother interim treatment technologies to detoxifying organic substances, and inactivating
reactive/corrosive substances is underway.
Concerning disposal technology, , necessary information and knowledge are being investigatedto develop measures that meet the needs of the disposal concept for which review of the waste
stream is in progress. Development of a storyboard3 on the progression of important events indisposal facilities has started for the purpose of identifying critical scenarios for solid waste disposal.
3.2.2 Technical strategy by sectors
In Phase 3, the plan is to determine the specifications of waste forms and their production
methods with proceeding characterization of solid waste. Therefore, in coordination among areasof characterization, processing/disposal, a study will be conducted to present appropriate overallmeasures for specific management approaches for solid waste, while reviewing necessary R&D
tasks. Specifically, the first step is to create processing/disposal options for solid waste byexamining pending issues related to processing technology, interim treatment, and disposal options.
Then, the options will be compared and evaluated using the property data that are becoming clear,and examinations will be conducted to establish a waste stream that is suitable for thecharacteristics of solid waste.
3.2.2.1 Characterization
It is necessary to improve evaluation of inventory for solid waste and continuously incorporate
them into solid waste management, including processing/disposal, while accumulating analytical

3

Storyboards provide a plain view of the behavior on the entire disposal system and allow for confirming
consistency in temporal and spatial scale.

57

data. In this case, efforts should be made for low-activity waste such as rubble, and high-activity
waste such as secondary waste generated by water treatment and waste generated from fueldebris retrieval, according to the characteristics of each type of waste.
For low activity waste, it is not so challenging to perform the analysis work itself. However, ittakes an immense amount of time to measure the entire quantity because of the enormous volume
of waste. Therefore, efficient analyses and analysis planning methods are needed along with thevolume reduction mentioned above. For that purpose, it is important to take an approach that
efficiently ensures the required accuracy. To achieve this, it is needed to aim for promoting efficient
analyses by simplified and speed-up, and for establishing an efficient analysis planning methodthat combines the DQO process4 with statistical methods.
For high radiation dose waste, sampling and analysis themselves are difficult, and the amount ofanalysis data to be obtained is limited. Thus, statistical inventory estimation based on theradionuclide transfer model becomes important. It is necessary to efficiently obtain actual sample
data with an analysis planning method that combines the DQO process with statistical methods,
such as ongoing efforts for sampling from cesium sorption apparatus and its analysis, which iscurrently in progress. The priority of the data to be collected should also be considered to enhance
the accuracy of the radionuclide transfer model.
Following the phase of analyzing samples that are easy to collect, characterization is now in thephase of collecting/analyzing samples that are important for waste management. Going forward, it
is important to develop a medium-to-long-term analysis strategy that defines the solid waste to beanalyzed, its priority, the objective of the analysis, quantitative targets, etc., and to proceed withanalysis/evaluation accordingly. It is useful to accumulate trial results and verify their validity inorder to establish a flow from the development of an analysis planning method that combines the
DQO process and statistical methods; data acquisition and analysis; the incorporation of theacquired data into an examination of processing/disposal methods and evaluation of the outcome;to the development of the fiscal analysis plan based on the evaluation results.
As for facilities for analysis, in addition to the existing facilities in the JAEA’s Ibaraki area, etc.,
the Radioactive Material Analysis and Research Facility Building-1 was completed in June, andTEPCO also plans to install new facility for analysis, enabling characterization of a variety of solid
waste in parallel. Since the target nuclides, analysis items, accuracy, and the number of samples
for analysis differ depending on the target solid waste, a structure should be established based on
the appropriate division of roles according to the characteristics of facilities and the objective ofanalysis.
3.2.2.2 Storage/management
For storage/management of solid waste should be appropriately made to the risk depending onradioactivity concentration and properties, etc. Moreover, it is important to reconsider measurement

4

A method to plan analytical samples for decision makings developed by U.S. Environmental Protection Agency

58

items and timing, etc., in terms of diverse information for characterization, while acquiring
necessary information through continuous monitoring and surveillance of the storage/management
status commensurate with the risks involved.
The Mid-and-Long-term Roadmap calls for eliminating temporary outdoor storage of all solid
waste, excluding secondary waste generated by water treatment and waste subject to reuse andrecycle, by the end of FY 2028. To achieve this goal, it is necessary to promote volume reduction
through incineration of felled trees, used protective clothing, etc., and cutting/crushing of metals
and concrete, and steadily consolidate storage inside buildings.
Due to the delay in installing the ALPS slurry stabilization/treatment system, the upper limit of the
cumulative absorbed dose (5000 kGy) has been exceeded before the commencement ofstabilization process, and the number of HICs that need to be transferred has increased. Although
there is no immediate impact on their integrity in a stationary state, it is necessary to manage HICs
appropriately until they are transferred and safely complete the early installation of thestabilization/treatment system and immediate transfer.
With regard to high-activity waste, such as waste generated from fuel debris retrieval, the issues
and countermeasures assuming further expansion of fuel debris retrieval in scale have beenclarified according to the results of research/development as of FY 2021. Going forward, reviews
should be performed along with the examination of the fuel debris retrieval methods. Measures
should be taken to ensure storage/management of solid waste that is expected to be generated
during fuel debris retrieval (trial retrieval, gradual expansion of the retrieval scale) before full-scale
retrieval.
The site also has solid waste stored before the accident, and a large volume of dismantled waste
is expected to be generated after the completion of fuel debris retrieval. Only increasing storage
capacity for solid waste will eventually reach the limit, so efforts should be made to reduce thevolume of solid waste to be generated as much as possible.
As volume reduction is extremely important for the safe and reasonable management of solid
waste according to the progress of decommissioning work in the future, the measures in progressshould be continued steadily. Since solid waste continues to be generated, it is important tocontinuously examine further possibilities by referring to advanced cases of overseas for morevolume reduction. It is recommended that volume reduction is realized in consideration of the
expected outcome and feasibility.
With an aim to reuse/recycle metals with extremely low surface dose rate, decontamination bymelting (decontamination by melting slag), are under consideration as metal decontamination
methods for recycling. As metal recycling with decontamination by melting slag has already beenused in many Western countries, it is considered a promising candidate technology. Thus, it isimportant to focus on the areas where the conditions are different between Western countries andthe Fukushima Daiichi NPS (target nuclides, etc.), and to evaluate the applicability of the method.
The portion of concrete debris for which the surface dose rate has been confirmed to beequivalent to the background radiation dose has already been recycled as roadbed materials.
59However, given that it will be continuously generated as the decommissioning work progresses tobe generated, it is necessary to appropriately evaluate the balance between the amount generated
and the amount recycled in the future and consider the lead time if additional measures are required.
3.2.2.3 Processing/disposal
To specify measures for the optimization and rationalization of the overall picture covering theentire waste stream, the trial examples of optimization/rationalization of processing/disposal
methods will be accumulated by waste stream to acquire findings on optimization by waste stream
widely. Therefore, it is necessary to continue R&D of processing and disposal technologies required
for the series of studies as shown in Fig. 16.
Regarding the processing technologies, pending issues in low and thermal processing
technology, for which research/development is promoted, should be addressed. Waste streams,
for which the application of normal-temperature and thermal processing technologies has not been
investigated, will be evaluated as necessary, and performance of solidified waste to be produced
to leach to groundwater after disposal will be evaluated. As for normal-temperature processing
technology, consideration is given to transformation of solidified waste as well as inspection
methods to verify the possibility of solidification. In the case of thermal processing technology, thefeasibility of the whole processing system, including supply and exhaust systems, is an issue in
addition to the solidification process, and therefore it is necessary to carry out examination in atimely manner according to the start time of processing.
Concerning disposal technology, to enhance the reliability of the disposal concept, it is necessary
to evaluate its feasibility based on a study of the long-term evolution behavior of the disposal
facilities in light of the characteristics of waste form and to incorporate the results into the discussionof the disposal concept. To appropriately allocate waste to a disposal concept that is shown to befeasible, knowledge on the sensitivity structure of the scenarios and parameters to radiation should
be expanded by adequately incorporating those characteristics of waste, changes in environmental
conditions in and around disposal facilities into the scenarios and parameters of radiation dose
assessment, and repeating tests. Using this knowledge to propose safe and reasonable disposal
options is important. Furthermore, after expanding the target of waste streams incorporating thisdisposal option, a group of disposal options will be examined with a bird-eye-view of all solid waste
at the Fukushima Daiichi NPS. Then, contributions will be made to considering specificmanagement approaches for solid waste in coordination with areas other than disposal, such aspresenting targets for waste form performance and the accuracy required for characterization.
In examining these, it is important to flexibly consider the most appropriate measures, taking into
account the actual use and economic feasibility by reflecting the newest findings and applying theconcept of the Best Available Techniques. As the examination progresses, and theprocessing/disposal methods for the overall picture of waste are finalized, it will be important toshare the examination process for optimization, such as by sharing the awareness of problems
with local communities and society.
60Generation ofwaste

Pretreatment andtreatment

Near-term storageand management

・ Improve accuracy of data on
properties, for disposal safetyassessment
・ Acquire additional data,
review transfer models
・ Quantify factors interferingwith waste conditioning

・ Based on treatment
schedules, update plans forrequired timing, capacity,
etc. of storage facilities
・ Update waste classifications
・ Change combinations ofwaste to be treated

Waste conditioning

・ Review waste specification
proposals to meet disposal
requirement proposals
・ Identify technologies that canbe applied
・ Improve quality control
processes

・ Review disposal methods(design of disposal facilities)
and assessment methods(scenarios, models,assessment parameters)

DisposalRequirement
proposals

・ Specify treatment
technology suitable for
waste
・ Designate waste
specifications

Policy fornarrowing
down

Disposal・ Specify reasonable andfeasible disposal
methods
・ Conduct disposal safetyassessments

Proposals fortreatment/disposal options

・ Manage risk throughmonitoring and surveillance・ Consider risk reduction
measures as necessary

Treatment

Waste
specification
proposals・ Set inventories

Storage

Stablestorage

Property
data

Characterization

DisposalReflect in TEPCO and solid
waste storage management plans

Fig. 16 Procedure to reasonably select safe processing/disposal methods of solid waste
The main technical issues and plans in the future described in this section are summarized asshown in Fig. 17.

61

Fig. 17 Main technical issues and future plans on waste management (progress schedule)623.3 Contaminated and treated water management
3.3.1 Targets and progress(Targets)(1) Under the three principles concerning the contaminated water issues ("Removing"
contamination sources, "Redirecting" fresh water from contamination sources, and "Retaining"
contaminated water from leakage), to reduce the stagnant water in the reactor buildings in FY
2022 to FY 2024 to about the half of the amount of the end of 2020 while continuing theoperation of the constructed water-level management system and controlling the generation
amount of the contaminated water to 100 m3/day or less in 2025. Moreover, to ensure stable
implementation of contaminated water management, measures against large-scale natural
disaster risks, such as tsunamis and storm rainfall, will be implemented in a planned manner.
(2) To arrange the relationship with a decommissioning process including full-scale fuel debris
retrieval beginning in the near future, and to promote examination of the measures of thecontaminated water management for medium-and-long term prospects.
(3) For ALPS treated water currently stored in tanks, measures will be taken for discharging
approximately two years after the “Basic Policy on Disposal of ALPS-Treated Water” (releasedin April 2021).
(Progress)
Stagnant water in buildings, that is, the contaminated water with a mixture of cooling watercontacted with the fuel debris and groundwater/rainwater flowed into the buildings is liquidcontaining a considerable amount of the dissolved radioactive materials (inventory) from theperspective of measures to reduce the risk from radioactive materials. Therefore, its hazard
potential is high and so is the Safety Management level, as the storage condition of such stagnant
water deviates from what is originally intended. For this stagnant water in buildings, excluding thereactor buildings of Units 1 to 3, where circulating water injection is ongoing, the process mainbuilding and high-temperature incinerator building storing contaminated water temporarily for
purification treatment, the treatment of stagnant water in buildings was completed in 2020, and theinventory was significantly reduced. However, the hazard potential is still high.
Currently, the following four measures are being implemented as contaminated water
management:(1) Efforts to promote contaminated water management in accordance with the three principles("Removing" contaminant sources, "Redirecting" fresh water from containment sources, and"Retaining" contaminated water from leakage")
The groundwater level in the vicinity of the reactor buildings was stably controlled at low levels
through multilayered contaminated water management such as land-side impermeable walls andsub-drains. The increase in the amount of contaminated water generated during rainfall also63tended to be controlled by repair of damaged roofs and facings on site. As a result, the amount ofcontaminated water generated decreased from approx. 490 m3/day (FY 2015) before themeasures were taken to approx. 130 m3/day (2021). In order to reduce the amount ofcontaminated water to 100m3/day or less by the end of 2025, roof repair and expansion of facing
range are being addressed while adjusting interference with other decommissioning work.
(2) Efforts to complete stagnant water treatment
In 2020, the treatment of stagnant water in buildings, excluding the reactor buildings of Units 1
to 3, the process building and high-temperature incinerator building, was completed. With the aimof reducing the amount of stagnant water in reactor buildings to approximately half of that at theend of 2020 between FY 2022 and FY 2024, the water level in the Unit 2 reactor building was
carefully lowered while parameters such as PCV pressure and dust concentration were monitored,
and the target level of T.P.-2,800 was first reached in March 2022.
It is planned to lower the water level in the reactor building while continuously lowering the subdrain water level in order to reduce the amount of stagnant water in the reactor building by half.
In association with this, the importance of issues in handling sludge containing α-nuclides(hereinafter referred to as the “α-sludge”) at the bottom of the reactor building is increasing. As
the particle size distribution and chemical composition of the α-sludge have been analyzed, it isexpected that most of the sludge can be removed by a filter with an appropriate pore diameter. In
order to complete the treatment of stagnant water in the process building and the high-temperatureincinerator building, moreover, methods for radiation dose rate surveillance or recovery are underconsideration for high-dose zeolite sandbags located on the lowest floor. In the case of a building
where the treatment of stagnant water has been completed and the floor surface has been
exposed, a method for recovering sludge located on the floor is being studied.
(3) Efforts for stable operation of contaminated water management
As for tsunami countermeasures, construction of the Kuril Trench tsunami tide walls werecompleted in September 2020, and the measures for closing building openings were taken in
January 2022, followed by the installation of the Japan Trench tsunami tide walls, , reinforcementof the land-side impermeable walls, relocation of sub-drain and other water collection systems
from the revetment side to higher ground, and transfer of sludge generated by decontamination
devices to higher ground. As a countermeasure for heavy rain, installation of drainage channel Dto eliminate the risk of inundation in the vicinity of Units 1 to 4 and reinforcement of discharge
functions of the existing drainage channel, etc., are underway.
While the importance of multilayered measures including land-side impermeable wall has notchanged, in light of the damage to equipment, such as brine leakage, it is important to strengthen
monitoring, procure and arrange spare parts and substitutes, and establish a framework for taking
restoration measures as soon as possible in the future. Furthermore, the earthquakes that
occurred on February 13, 2021, and March 16, 2022, did not cause leakage in tanks for storing
the treated water, but caused sliding of the tanks (53 units and 160 units, respectively). Moreover,64

displacements exceeding the manufacturer's recommended limits5 have been confirmed in someof the connecting pipes, however, since the connecting valves are fully closed, the stored waterin the tanks will not leak, even if it should break.
(4) Efforts toward discharging ALPS-treated water into the ocean
On April 13, 2021, under the overriding principle of Balancing between Reconstruction andDecommissioning, and on the premise of ensuring safety and implementing comprehensive
measures to prevent reputational damage, the Government announced the basic policy fordischarging ALPS-treated water into the ocean from the Fukushima Daiichi NPS after
comprehensive discussions at expert meetings for more than six years. In addition, theGovernment requested TEPCO to proceed with preparations, including the installation of a
specific discharge system, aiming to start the discharge of ALPS-treated water into the ocean in
about two years.
In response to this policy, on April 16, 2021, TEPCO indicated their approach to ensuring safety
through further efforts and in compliance with regulatory standards pursuant to laws andregulations; minimizing reputational damage; providing compensation in the event of reputational
damage; and addressing issues for the future. TEPCO has also started working to provide abriefing for stakeholders, and to obtain permission for the implementation plan.
As part of its initiatives since the announcement of the basic policy, the government compiled
and disclosed immediate measures at the second meeting of the Cabinet Meeting for the Steady
Implementation of the Basic Policy on Disposal of ALPS-treated Water and a specific action planat the third meeting. The task force on monitoring and measuring the marine environment and theExpert Meeting for Marine Monitoring related to ALPS-treated water were established in June
2021 to enhance marine monitoring. In July 2021, the government signed the Terms of Referencewith the International Atomic Energy Agency (hereinafter referred to as “IAEA”) and requested
support for the discharge of ALPS-treated water.
Meanwhile, TEPCO announced in August 2021 the status of the facilities study for ensuringsafety and published the results of its assessment that the impact of the discharge of ALPS
treated-water into the ocean on human and the environment would be extremely small in theRadiological Impact Assessment Regarding the Discharge of ALPS Treated Water into the Sea(Design stage) in November 2021 to solicit comments. In December 2021, TEPCO submitted
Application Documents for Approval to Amend the Implementation Plan for a Specified Nuclear
Facility for ALPS Treated Water Dilution/Discharge Facilities and Related Facilities to the Nuclear
Regulation Authority for review on the operation method of offshore discharge facilities and safety
during discharge into the ocean, and gained approval in July 2022.
In addition, the IAEA conducted a safety review on the handling of ALPS-treated water in
February 2022 and a review of the regulations of ALPS-treated water in March 2022 based on the5

It is a reference value that allows the pipe to be used safely even if displacement occurs. The design value has
a margin of about 2 to 4 times to this value.

65Terms of Reference with the government. The IAEA published review results reports in April 2022
and June 2022, respectively.
The discharge of waste liquid generated in nuclear facilities into the ocean, pursuant to the law
with a sufficiently small radiological impact on the human population and the natural environmentis a method recognized globally and widely adopted in Japan and abroad. On the other hand, it isalso a fact that there have been concerns about reputational damage due to the discharge of
ALPS-treated water into the ocean. Therefore, efforts should be continued to deepen
understanding to eliminate such concerns. Therefore, greater transparency is required, forexample, by repeatedly providing explanations in an easy-to-understand and careful manner,
mainly by TEPCO, in order to increase understanding of (1) an operation plan for offshore
discharge; (2) the effects of radioactive material such as tritium contained in the water to bedischarged to the ocean on the human body; and (3) the method for verifying the operation status
as the basics for implementing safe discharge, and by verifying these through reliable third parties
such as IAEA in cooperation with organizations concerned, and by delivering accurate information.
TEPCO's planned discharging system, if operated reliably, will have no adverse effects onhumans and the environment, and therefore it is an important issue to operate the system"reliably" “as planned”. The following is a summary of the progress made by TEPCO on each of
the items listed in Technical Strategic Plan 2021.
In the operational phase, develop a series of operation plans including system operation,
analysis of ALPS-treated water, flow control of the treated/diluted water, marine monitoring,
maintenance, and troubleshooting, and then develop a system plan that minimizes risks andeliminates social concerns=> TEPCO's system and operation plans will be approved by the Nuclear Regulation Authority
in July. However, the nuclides to be measured/assessed before discharge into the ocean
will be selected after verifying the nuclides that can be significantly present in ALPStreated water. NDF provides technical advice and support on the selection method of
nuclides to be analyzed and the evaluation method of nuclide concentration.



Perform a radiological impact assessment on the human population and the naturalenvironment, and disclose evaluation results based on the specific discharge plan=> In April 2022, TEPCO submitted to the NRA the statement of the radiological impact
assessment revised based on the review by IAEA and the international experts as well as
discussion with the NRA. Based on the selection results of the nuclides to be assessed,
the radiation environmental impact will be verified.

Verify safety by experts from the IIAEA and other agencies=> In February 2022, the IAEA conducted a safety review on the handling of ALPS-treatedwater and announced that preventive measures were adequately taken in the design of66

the discharge system in light of international safety standards and that the radiologicalimpact on humans is significantly smaller than the reference values proposed byinternational organizations and the level specified by regulatory authorities. The next
review mission is scheduled for late 2022, and a comprehensive report with final
conclusions and findings will be published before the discharge of ALPS-treated water
begins.
Develop a plan to strengthen marine monitoring, and perform marine monitoring before thedischarge=> The Government’s Monitoring Coordination Council, held on March 30, 2022, provided aplan for strengthening and expanding marine monitoring by the government (MOE, NRA,etc.), TEPCO, and Fukushima Prefecture. The monitoring started in April 2022. TEPCO isproactively conducting monitoring in cooperation with the government and local
governments, etc.



Education and training on analysis for parties concerned including contractors=> TEPCO explained education and training plans on analysis to the NRA in the open
screening panel. A review was performed on competence management methods related
to analysis, and education and training.



Development of strategies to provide accurate and understandable information domesticallyand internationally without causing anxiety from a social perspective, and timely disseminationof the status of preparations=> TEPCO has continuously held 1F tours and round-table talks for residents living in 13
municipalities along Hamadori and other areas in Fukushima Prefecture, anddisseminated information on decommissioning and ALPS-treated water through the local
newspaper advertisement. In addition, TEPCO has accepted site visits by foreign
government officials, etc., as well as provided the latest information on the discharge of
ALPS-treated water into the ocean not only in Japanese, but available in English, Chinese,and Korean on TEPCO’s “Treated Water Portal Site”.

Ensuring implementation of measures against reputational damage as set forth in the
Government's basic policy announced in April 2021=> The Government announced an action plan at “the third meeting of the Cabinet Meetingfor the Steady Implementation of the Basic Policy on Disposal of ALPS-treated Water”(revised in August 2022) held in December 2021. Based on the action plan, TEPCO ismaking efforts to minimize reputational damage through reviews by the NRA and the IAEA,
and safety checks by local governments based on agreements to ensure the safety ofdecommissioning. NDF promotes understanding and disseminating accurate informationaccording to the interests of the recipients through meetings with relevant organizations
in foreign countries and international conferences673.3.2 Key issues and technical strategies to realize them
3.3.2.1 Issues in the future treatment of stagnant water in buildings
The following three points are the key issues for the future treatment of stagnant water inbuildings.
(1) Prevention of spreading α-nuclides
At the bottom of the torus room of the reactor building, stagnant water in which α-nuclides fromfuel debris exist in the form of fine particles (α-sludge) and ions, and a relatively high concentrationof total α-nuclides has been detected. Since the effective dose factors of α-nuclides is remarkably
high when inhaled or ingested, special management and countermeasures are required if αnuclides spread to stagnant water in buildings or water treatment systems. The spread of αnuclides should be as limited as possible to avoid such a situation.
The investigation in FY 2021 revealed the following two points on the spread of α-nuclides.
The highest total α concentration to date was detected in accumulated water collected in theMain Steam Isolation Valve room of Unit 3.

A relatively high total α concentration was detected in the bottom sludge of the D1 and D2
tanks in the Area E.

The total α concentration of the accumulated water collected in the Main Steam Isolation Valve
chamber of Unit 3 was about three times (1.7 × 106 Bq/L) that of the stagnant water collected fromthe bottom of the reactor building of Unit 3, which had the highest concentration. It is presumed
that this accumulated water is part of the water inside the PCV flowing directly into the Main Steam
Isolation Valve chamber from the damaged expansion joint of the main steam pipe connected to
the PCV. Moreover, it was found that the total α concentration of the collected accumulated water
would decrease to about 1/1000 by filtration, indicating that most of the α-nuclides exist as fineparticles.
Tanks D1 and D2 in Area E store water collected from residual water at the bottom of the tanks
generated by dismantling flanged tanks that stored RO-enriched saltwater. As a result of
measuring the total α concentration of the water mixed with sludge at the bottom of the tanks, thetotal α concentration (5.3 x 103 Bq/L) of the same level as the stagnant water in buildings was
detected. This bottom sludge is to be recovered from the top manway of the tank by feeding an
underwater pump.
As described above, the situation of α contamination in the Unit 3 reactor building and thepresence of α sludge due to the treatment of residual water at the tank bottom are becoming
apparent. In particular, attention should be paid to the fact that α contamination spreads mainly
through fine particles (sludge components). At present, a total α concentration in the order of 10
Bq/L is maintained at the cesium sorption apparatus (SARRY/SARRYII) inlet, and the spread ofcontamination to the downstream side is suppressed. However, as the stagnant water level of thereactor building is lowered further in the future, more sludge at the bottom of the building may be68mixed, and the total α concentration at the water treatment system inlet may rise. TEPCO isconsidering installing filter systems in the subsequent stage of the cesium sorption apparatus in
response to such concerns.
(2) Further lowering of groundwater levels to reduce the amount of contaminated water generated
Since there is highly concentrated stagnant water at the bottom of the torus room of the reactor
building, a sudden change in concentration during treatment of the stagnant water will interferewith the treatment system in the subsequent stage. Therefore, the water level of stagnant waterin buildings will be carefully lowered to approximately 10 cm in 2 weeks for each building.
Although the water level is controlled in the floor sump in the buildings with exposed floor
surfaces, there is a possibility that the sump may overflow temporarily during heavy rains such as
typhoons. The overflowing water must be treated as stagnant water in the building, which is highly
contaminated by fuel debris, and the water level difference with the sub-drain must be secured(800 mm or more). Therefore, in preparation for the risk of deviation from the limiting conditions
for operation (LCO) during heavy rain, the sub-drain water level is maintained higher in advance,
causing an increase in the inleak into buildings. Since the floor of these buildings is higher thanthe level of stagnant water in the reactor building, water that inleaks into the floor sumps during
heavy rainfall is derived from rainwater and groundwater. As the risk of leakage of stagnant waterin the reactor building does not increase even if the water level rises, it is necessary to review thewater level management method for the buildings where exposed floor surface has been achievedin the future.
(3) Stagnant water treatment in process main building and high-temperature incinerator building
As the basement floors of the process main building and the high-temperature incinerator
building are storing stagnant water, TEPCO aims to lower the water level to expose the floor
surface of the buildings from FY 2024. To realize this, it is essential to take measures against highdose zeolite sandbags placed on the basement floors of the process main building and the hightemperature incinerator building and install temporary storage tanks for stagnant water in place ofstorage in the basement floors.
In the basement floors of both the process main building and the high-temperature incinerator
building, zeolite sandbags placed shortly after the accident are found to exist in a high-dose state,
and the maximum surface dose from the sandbags is extremely high at approximately 4,400
mSv/h, and activated carbon sandbags also exist. When these basement floors are exposed, it isexpected that the radiation dose will increase significantly at the openings of the above-groundfloors due to the loss of water shielding.
The procedure for recovering zeolite sandbags under consideration is to first collect as manyzeolite sandbags as possible in a submerged environment to increase work efficiency, then transfer
the collected zeolite and other materials to the ground level using a recovery robot (ROV + pump),
desalinate and dehydrate them in the building, seal them in metal storage containers, and transfer
them to temporary storage facilities. The first step of collecting will be carried out in FY 2023, and69

the second step of containing will be from FY 2023 to FY 2024. In this task, zeolite will be collected
and recovered by suction in the form of particles, which may apply to the recovery of high-dose
sludge deposited on the floor surface of the reactor building to be planned, providing criticalknowledge for the future progress of decommissioning work.
However, the basement floors of the process main building and the high-temperature incinerator
building have been used as storage tanks for tens of thousands of cubic meters worth of stagnant
water in buildings, where water with different chemical properties and radioactivity transferred fromthe Unit 1 to 4 buildings has been mixed, averaged, and treated by the cesium sorption apparatus.
For this reason, studies are underway on temporary storage tanks for stagnant water that will takeover the following functions that the process main building and the high-temperature incinerator
building have performed.
Receiving stagnant water in buildings

Stagnant water buffer for stable operation of cesium sorption apparatus (KURION, SARRY,
and SARRYII)

Concentration averaging of stagnant water in each buildingSettlement of sludge

These temporary storage tanks for stagnant water will be installed on the fourth floor of theprocess main building. The basement floor of the process main building after tank installation will
be used only when the inflow volume increases during heavy rain. To take over the functions
described above, temporary storage tanks for stagnant water will consist of two types of tanks: atemporary receiving tank for receiving water and settling sludge and a temporary storage tank forhomogenizing the water concentration. The capacity of the temporary receiving tank is assumed tobe approximately 10 - 20 m3, and that of the temporary storage tank is approximately 20 m3. The
capacity is considerably smaller than that of the basement floors of the the process main building(maximum capacity: approximately 16,000 m3) and the high-temperature incinerator building(maximum capacity: approximately 5,000 m3). In the future, an examination from operational
aspects is needed to maintain the functions even with a small capacity. The installation work of thetemporary storage tanks for stagnant water is scheduled from FY 2023 to FY 2024, and these tanks
will be operated from FY 2024.
3.3.2.2 Issues of contaminated water management considering the decommissioning
process such as fuel debris retrieval
The following two points are the key issues of contaminated water management considering thedecommissioning process such as fuel debris retrieval.
(1) Examination of water treatment systems for fuel debris retrieval
In examining water treatment systems for fuel debris retrieval, it is essential to review the overall
picture of how to share the functions with the existing treatment systems for stagnant water inbuildings (SARRY, ALPS, etc.) and establish an appropriate configuration. At the same time,planned replacement of the existing water treatment systems is also required. To carry out such70

an examination, determination of the required specifications and basic design for the water
treatment systems for fuel debris retrieval must be implemented promptly.
When retrieving fuel debris, contaminated water containing a large amount of fine particles isgenerated by fabrication including cutting and other processes, and α-nuclides in fuel debris may
exist in various forms such as fine particles, ions, and colloids. Because the water quality of suchcontaminated water depends on fabrication method including cutting and other processes, it isdifficult to assume the water quality in a situation where the fuel debris retrieval method has notbeen determined. An issue arises that the water treatment systems for fuel debris retrieval shouldhave a complicated system configuration to cope with a wide range of water quality and different
forms of α-nuclides.
However, analysis of the stagnant water in buildings has shown that the concentration of total
α can be reduced to 1/100 to 1/1,000 by filtration, indicating that most α-nuclides can be removed
by simple filtration. Since simple fabrication including cutting and other processes without the useof chemicals lead to only small changes in chemical water quality, most α-nuclides are generated
as fine particles, as in these analyses, and the concentration of soluble α-nuclides may be
maintained at a low level. Therefore, it is important to verify the form and particle size of α-nuclides
at the sampling points and incorporate them into the system design for further expansion of fueldebris retrieval in scale.
To establish fabrication methods including cutting and other processes, laboratory tests should
be conducted to determine their impact on the chemical changes in water quality, which will enable
the establishment of realistic water quality conditions for contaminated water and lead torationalization and improved reliability of the water treatment systems.
(2) Medium-and-long term measures for contaminated water management systems
It is necessary to ensure that periodical inspection and updating of equipment, including landside impermeable walls, sub-drain systems and existing water treatment systems (e.g. SARRY,
ALPS), is implemented in order to maintain the effectiveness of contaminated water management
over the medium-to-long term. For this purpose, it is important to anticipate various risks, such asdeterioration of system functions caused by aging, metallic fatigue due to traffic loads, damage ofpiping caused by natural disasters; to procure/arrange backup and alternative items for theenhanced structure for monitoring and early recovery, and for stable operation; and to promote
maintenance/management and system updates in a planned manner.
While the current contaminated water management is shifting to a certain stable state, in
addition, it takes a long time to complete fuel debris retrieval. Along with the selection of methods
for further expanding the scale of fuel debris retrieval currently in progress, it is important to see
a medium-and-long term, overlook the current contaminated water management anew, andexamine the principles of more stable contaminated water management and more appropriate
maintenance/management of each system. Furthermore, the interference with fuel debris retrieval

71

work needs to be considered as contaminated water management in anticipation of thedecommissioning process.
As exemplified in 3.1, partial submersion method and submersion method are currently under
examination for fuel debris retrieval. In addition to verification of actual site applicability andtechnical feasibility, both methods need consideration of measures to prevent contaminated waterfrom leaking out from inside the building and control groundwater inleak into the building from theoutside. In the future, it will be necessary to consider medium and long-term contaminated water
management and fuel debris retrieval methods.
3.3.2.3 Issues for discharging ALPS-treated water into the ocean
In July 2022, TEPCO gained approval from the NRA on facilities for offshore discharge of ALPStreated water, their operation methods, and safety during discharge into the ocean. TEPCO also
underwent a review on safety in handling ALPS-treated water by the IAEA, indicating thatpreventive measures were adequately taken in the design of the discharge facilities in light ofinternational safety standards and that the radiological impact on humans is significantly smaller
than the level specified by regulatory authorities.
Going forward, it is an important issue for TEPCO to operate the established plan "reliably", and
it is necessary to ensure the implementation of each plan (system, operation, information
distribution, etc.), to perform check and review, and to review and expand the plan as needed, as
well as to ensure its transparency. It is necessary to build systems based on the approved
implementation plan and ensure that education, training, and other preparations for its operation
are provided.


Ensuring establishment of planned facilities and their reliable operation (including system
operation, analysis of ALPS-treated water, flow control of the treated/diluted water, marine
monitoring, maintenance, and troubleshooting)

Reassessment of radiation impacts on human and environment based on the selection
results of nuclides to be analyzed and publication of the assessment results

Perform marine monitoring before, during and after the discharge in accordance with thedeveloped marine monitoring planContinued implementation of the following➢ Verify safety by experts from IAEA and other agencies Education and training on system
operation and analysis, etc., for parties concerned including contractors➢ Development of strategies to provide accurate and understandable information
domestically and internationally without causing anxiety from a social perspective, andtimely dissemination of the status of preparations➢ Ensuring implementation of measures to prevent reputational damage as set forth in the
Government's basic policy announced in April 2021

72

In order to prepare for ensuring prompt and reliable site usage after the discharge of treatedwater, TEPCO also needs to develop a plan to discharge in accordance with the site use plan andappropriately revise the plan according to the situation, in considering concentration of tritiumcontained in treated water in tanks and attenuation.
NDF will provide technical and professional support for TEPCO's construction of facilities andpreparations for the start of operations, while promoting distribution of accurate information andincreasing understanding through meetings with relevant organizations in other countries andinternational conferences in line with the interests of those who will receive the information. NDF
will also ensure that TEPCO implements measures to minimize reputational damage, and thatTEPCO takes action with adequate and sufficient compensation in the event of reputational
damage.
3.3.2.4 Summary of major technical issues
The main technical issues and plans described in this section are summarized as shown in Fig. 18,
and Fig.14 shows the future plans for the water treatment system for fuel debris retrieval.

Fiscal year
Relatedmilestones

2022

2023

2024

2027

2033(year)▽To control the contaminated water generation amount to 100 m3/day or less(in 2025)
To reduce stagnant water in the reactor building to approximately half that of the end of 2020 (FY 2022 to FY 2024)

Stagnant water in buildings

Contaminated water management

Maintenance management operation of a groundwater bypass, a sub-drain, and a land-side impermeable wall

ContaminatedSite pavement inside the land-side impermeable wall (mountain-side)
water generation
amountRepair broken parts of roofs (incl. the installation of a large cover on Unit 1 R/B)
Units 1 to 3
Reactor
Buildings

Water level lowering for a 50% reduction

Implementing required measures in accordance with the stage of fuel debris retrieval

α-nuclides removal equipment
DesignManufacture and installation

Operation

Units 1 to 4
TurbineExamination of methods for collecting sludge on the floor
Buildings etc.

Processmainbuilding,
Hightemperatureincinerator
building

DesignManufacturing/installatin/ of equipment for collecting sludge on the floor＜Legend＞

Alternative tank
Manufacture and installation

Measures for zeolite sandbags
Manufacture
Designand installation：The period of on-site work

：Technical study on on-site work
Collection：The period in which change is expected

Water level lowering for
exposing the floor surface

Removing stagnant water on premises
Dismantling underground water storage tankConceptual study

Measuresagainst stagnant
water

Treated-water
management

Design/removal

Examination of methods for treating untreated water in tanks
Experimental prior treatment

Treating untreated water in tanks

Discharge system
Installation
Preparation

Marine monitoring

Measures against
natural disaster

Installation of tsunami tide walls in the Japan Trench
Maintenance of drainage

Fig. 18 Key technical issues and future plans on contaminated water and treated water
management and natural disaster preparedness (progress schedule)

733.4 Fuel removal from spent fuel pools
3.4.1 Targets and progress(Target)(1) The aim is to complete fuel removal from all spent fuel pools of Units 1 to 6 in Phase 3-[1] of
the Mid-and-Long-term Roadmap.
(2) While the return of residents and reconstruction in the surrounding area is gradually advanced,
to carry out a risk assessment and ensure safety including preventing dispersion of radioactive
materials and to start removal of fuel in SFPs in FY 2027 to FY 2028 for Unit 1 and FY 2024
to FY 2026 for Unit 2.
(3) The fuel in Units 1 to 4 that were affected by the accident are retrieved from the SFPs andtransferred to the Common Spent Fuel Storage Pool, etc., where they are appropriately stored
so that they are in a stable management state. In order to secure the Common Spent Fuel
Storage Pool capacity, the fuel stored there is transferred to and stored in Dry Cask Temporary
Custody Facility.
(4) To perform the evaluation of long-term integrity and the examination for treatment for the
retrieved fuel and to decide the future treatment and storage method.
(Progress)
In Unit 1, from the perspective of further reduction of radioactive dust dispersion risk, a method
in which the whole operating floor was covered with a large cover to remove rubble and fuel from
SFP inside the cover, was adopted. In preparation for the installation of large covers andsubsequent rubble removal operations, measures to prevent and mitigate the dropping of rubble,
such as installing supports for overhead cranes and fuel handling machines, and curing the SFP inorder not to affect fuel in SFP, were completed in November 2020. The removal of the existing
interfering building cover (remaining portion) was completed in June 2021. Subsequently, the areaaround the reactor building has been improved. Still, delays in removing SGTS piping (removal ofhigh-dose pipes by remote control) caused delays in the preparatory work. In light of the review
status of the application of the new seismic design policy presented by the NRA, TEPCO states in
its Mid-and-Long-term Decommissioning Action Plan 2022 that it will reconsider the installation
process of the large cover for Unit 1 due to the construction work interference (caused by the delay
in preparatory work). The installation period in the progress schedule is set until around the end of
FY2024, with the goal of completing the installation by FY2023. Fuel removal in Unit 1, a milestone
in the Mid-and-Long-term Roadmap is expected to begin in FY 2027 - FY 2028 as planned. TEPCO
plans to obtain approval of the implementation plan for installing the large cover and to commence
the installation work of the main unit.
For Unit 2, a method in which the upper part of the operating floor will not be dismantled and withaccess from the working platform for fuel removal to be installed on the south side of the reactor
building was adopted from the perspective of further reduction of radioactive dust dispersion risk
similar to Unit 1. For constructing the working platform, installation of the base mat of working
74

platform for fuel removal started in May. Based on the results of dose surveillance on well-plug ofthe operating floor and conducted in 2021, decontamination and installation of shielding on theupper part of the well were carried out. The effectiveness of radiation dose reduction was recheckedin May 2022. Preparations are underway for fuel removal, including the transfer of the existing fuelhandling machine and further decontamination/shielding.
The policy is that fuel removal from Units 5 and 6 is planned so as not to interfere with operationsin Units 1 and 2. In Unit 6, fuel transfer from the SFP to the common spent fuel storage pool began
in August 2022.
Securing the available capacity of the Common Spent Fuel Storage Pool and transfer of some
fuel in the Common Spent Fuel Storage Pool to Dry Cask Temporary Custody Facility are required
to remove all the fuel in SFPs, including Units 5 and 6, and store them in the Common Spent Fuel
Storage Pool. For this purpose, TEPCO is working on expanding storage capacity of Dry Cask
Temporary Custody Facility and systematic off-site transportation of new fuel.
Such efforts will be made to complete fuel removal in all units in 2031.
3.4.2 Key issues and technical strategies to realize them
For Units 1 and 2, it is necessary to advance the work steadily to realize the determined new
removal method.
3.4.2.1 Fuel removal from SFPs
In promoting the project, it is important to make assessment of safety in association with workand confirming that necessary and sufficient safety is ensured. Moreover, it is essential tocomprehensively consider technical reliability, rationality, promptness in the work schedule, actualsite applicability and project risk, etc.
For Unit 1, the installation of the large cover, and the removal of leftover objects such as rubble
on the operating floor will be promoted. Although overhead crane support is installed on the upper
part of the operating floor for fall prevention, it is still in an unstable state. Therefore, removing theoverhead crane in a safe and reliable way is one of the main issues to prevent it from collapsing
onto the fuel handling machine and falling into SFP. Although TEPCO has drafted the removal
method of the overhead crane, the information on the condition of the lower part of the roof slab islimited at present, requiring reverification by a detailed investigation after the removal of the slab.
There is a risk of delay in the crane dismantling process depending on the reverification result.
Therefore, it is important to plan work procedures after identifying required tasks such as surveys
and verification, promptly investigate overhead cranes, etc., as soon as investigation becomes
possible, and incorporate them into safety assessments and rubble retrieval plans, including riskcases.
Although the well-plugs of Unit 1 have been evaluated by the Study Committee on Accident
Analysis of the Fukushima Daiichi NPS to be about two orders of magnitude less contaminatedthan several tens of PBq of Units 2 and 3, those in Unit 1 become deformed and unstable due to75the impact of the explosion at the accident. For this reason, TEPCO is studying the impact of afall on the PCV during an earthquake. Based on the study results, it is necessary to make acomprehensive decision on how to handle these well-plugs, and by taking into consideration theimpact on the removal of fuel from SFP and fuel debris retrieval in the later stage, and by
performing thorough safety assessments.
While applying overseas findings, a detailed handling plan for 67 fuel assemblies with damaged
cladding tubes, which have been stored in Unit 1 SFP since before the accident, is underdevelopment toward the completion of fuel removal in 2031. In particular, efforts should be madeto ensure verification of the post-accident condition, examination/development of handling methods,
and risk study associated with handling.
In Unit 2, fuel in SFP will be removed from the opening on the south side of the operating floorusing a fuel handling machine composed of a boom-type crane-system, which has not yet beenused for nuclear facilities in Japan. Since it is a new system, it is important to do the following: ①
to set up an appropriate design/manufacturing schedule with margins, ② to perform mockup
tests fully simulating on-site situations and operation methods and ensure feedback on the results
to design and production, and ③ to be sufficiently familiar with the operation and functionality ofsystems beforehand in preparation for removal by remote operation.
To install a fuel handling system, it is necessary to steadily carry out preparatory work, including
installing an anterior chamber on the working platform and an opening on the south side of theoperating floor of the reactor building. Fuel removal from the SFP basically assumes unattended
operation by remote control. However, staffed operation is also assumed during installation ofsome system and troubleshooting. Therefore, TEPCO plans to carry out decontamination andinstall shields in FY 2023 after completing the transfer of the existing fuel handling machine, etc.
Under the current plan, there is a risk that the work area after decontamination will becontaminated again, and the process will be delayed due to establishing the opening on the south
side of the operating floor after decontamination. Therefore, it is important to take thoroughmeasures to prevent dust dispersion when establishing an opening.
3.4.2.2 Decision of future treatment and storage methods
The future treatment and storage methods for the fuel in SFPs need to be decided after
considering the impact of seawater and rubble exerted during the accident. The impact of seawaterand rubble has been evaluated for the fuel removed from Unit 4, and it is expected that the impact
is small. However, based on the situation of the fuel to be retrieved, it is necessary to advance theevaluation of long-term integrity and the examination for treatment and to decide the future
treatment and storage methods.

76

The main technical issues and plans described in this section are summarized as shown in Fig.
19.
Fiscal year

2020

Related milestones

Unit 1

2021

2022

2023

Complete installation of Unit 1 large cover(around FY 2023)▽

Removal of building
cover(remaining parts)

2024

2026

2032(yr)

To complete fuel removal (in 2031) ▽Start Unit 2 fuel retmoval(FY 2024 to FY 2026)

Start Unit 1 fuel removal(FY 2027 to FY 2028)

Installation of large cover
Removal of rubble, the overhead crane, etc.
/well-plug disposal /decontamination and shielding of an
operating floor/installation of fuel handling machine, etc.

Fuel removal
Removing high-dose equipment/ Draining the pool

<Legend>

Unit 2

Yard cleanup/
Soil improvement, etc.

: Fuel retmoval work
: The period in whichchanges are expected: Works other than fuelretmoval: The period in whichchanges are expected

Decontamination and shieldingof operating floor
Installation of a working platform on
the south side and an opening/fuelhandling machine installation, etc.

Fuel removal

Removing high-dose equipment/ Draining the pool
Unit 3 fuel removal

Units 3 and 4
Removing high-dose
equipment in Unit 3/ Draining the pool
Removing high-dose
equipment in Unit 4/ Draining the pool

Units 5 and 6

Unit 6
fuel removal

Suspended while work
is performed at Unit 2

Suspended while
work is performed
at Units 1 and 2

Unit 5 fuel removal

Dry cask manufacturing

Common Spent Fuel
Storage Pool
Cask

Transfer from the Common Spent Fuel Storage Pool to the
Dry Cask at the Temporary Cask Custody Area
Expanding of storage capacity in Dry
Cask Temporary Custody Facility

Examination, design and installation of dry storage facility (for Common Spent Fuel Storage Pool)

Carrying out fuel from Common Spent Fuel
Storage Pool/Dry storage on higher groundFig. 19 Key technical issues and future plans for fuel removal from SFPs (Progress schedule)77

4. Analysis strategy for promoting decommissioning
4.1 Uncertainty of fuel debris, etc. and importance of analytical results
The accident at the Fukushima Daiichi NPS was the first core meltdown accident at BWRs in
the world, and there are no records of temperature and other plant parameters due to loss of powerat the accident. In addition, many uncertainties remain regarding the state inside the reactors, thestate of the fuel debris, and FP release paths, etc., due to the unclear operational status of thesafety equipment and the injection of seawater to bring the accident under control. If the range of
uncertainty is reduced, there will be no need to include excessive safety margins in safetyassessments and safety measures for handling and storing of fuel debris, and thus, the promptness
and rationality of decommissioning will be improved. In addition to conventional sample analyses,
studies on reducing uncertainty of fuel debris properties by other measurement methods havealready started since FY2020 by The Project of Decommissioning, Contaminated Water andTreated Water Management.
The analysis results of solid waste are important basic information for the study on
processing/disposal methods for various kinds of waste generated by the accident. The analysis
results of fuel debris are applied in a number of areas, including retrieval methods, storage
management, necessity of treatment, investigation to determine the cause of the accident, andimprovement of nuclear safety. Their relationship changes with the progress made in
decommissioning of the Fukushima Daiichi NPS. It is important to correctly recognize that theanalytical results are "one of the important criterion for decisions" for reducing the range of
uncertainty in the above examination for facilitating decommissioning. TEPCO, incorporating
analysis results in each decommissioning process, should take the lead in establishing anddeveloping analysis systems, facilities, and functions that can efficiently collect and evaluate
analysis results.

4.2 Three elements of analysis strategy
To safely and steadily proceed with decommissioning of the Fukushima Daiichi NPS, it isnecessary for TEPCO to establish and develop facilities for analysis and the functions required forhandling of solid waste or fuel debris. In addition, it is important to build a system that effectively
utilizes analyzed results for each decommissioning operation.
In order to obtain good analysis results, it is effective to properly maintain ① the methods andsystems for analysis, ② the quality of the analysis results, and ③ the size and quantity of sample.

4.3 Current status of establishing an analysis system and strategy
As an essential facility for decommissioning of the Fukushima Daiichi NPS, the JAEA is
proceeding with the construction of Radioactive Material Analysis and Research Facilities adjacentto the Fukushima Daiichi NPS under the supplementary budget of the Government (FY2012). At
78

commencing their operations, they will be designated as controlled areas of the Fukushima Daiichi
NPS, which has the advantage that off-site transportation is not required. Leveraging this, it iseffective to promptly identify basic physical properties, and incorporate them into safetyassessment and work procedures. The objectives of laboratory-1 are solid waste analysis and thirdparty analysis of ALPS-treated water, and laboratory-2 is intended to conduct fuel debris analysis.
The facility management building has been operating since 2018. The construction of laboratory-1
was completed in June 2022, and the controlled area and other areas were set as a part of thespecified nuclear facility in October, then, analytical operation using radioactive materials has
started. The laboratory-2 is in the process of screening application for approval of implementation
plan changes and selecting the operator. TEPCO is also considering the construction of analysis
facilities (comprehensive analytical facility) in response to the future needs of analysis including
analysis of fuel debris and solid waste in addition to current routine.
As shown in Fig.20, since the laboratory-2 and the comprehensive facilities for analysis arescheduled to commence operation after the trial retrieval of fuel debris. Analysis will be conductedat the facilities for analysis in the Ibaraki area until the laboratory-2 is operational. Even after theoperation commencement of the laboratory-2, if special techniques are required for sample
pretreatment or if analysis and testing requires an extended period, it is more efficient to perform
analysis in the Ibaraki area, because (i) there are many researchers and engineers, (ii) many typesof special analysis devices are available, and (iii) there are a large number of hot cells withcontainment and shielding functions and application options, and to prioritize promptness on-siteand adjacent areas of the Fukushima Daiichi NPS. As for solid waste analysis, as trial retrieval offuel debris progresses, it is anticipated that solid waste that TEPCO has not had experience withpreviously, such as fine fuel debris and filters that have captured FPs, will be generated. Regarding
high dose solid waste for which there is limited experience, it is desirable to analyze solid waste in
the Ibaraki area for the same reasons as for the fuel debris described above, and it is necessary tocontinue it in the Ibaraki area for some time after the Laboratory-1 is put into operation. Based on
the above, since target nuclides for permission for use and the situation with or without off-sitetransportation differ between facilities for analysis in the Fukushima Daiichi NPS site/adjacent areas
and those in the Ibaraki area, it is effective to assign roles according to the characteristics shownin Fig. 21 and expand the analysis data of fuel debris and solid waste. However, since all thefacilities for analysis in the Ibaraki area have been in operation for more than 30 years,
considerations on measures are required for aging facilities that will be used continuously.

79

Fiscal Year

2022

2023

2024

Environmental
improvement in buildings

Fuel debris
retrieval(Unit 2)2025 and after

Trial retrieval(internal investigation/fuel debris sampling)

Characterization of fuel debris

Manufacturing /installationof retrieval device

Gradual expansion offuel debris retrievalInternal investigation of RPVTransportation outside the site
Elimination of temporary outdoor storage

Rubble etc.(rubbles, felled trees, used protective clothing)

Solid waste

Secondary waste generated by water treatment (Sorption vessels, waste sludge, concentrated waste liquid slurry)

Analysisfacilities in
Ibaraki (JAEA,
NFD, NDC)
Lab.

1
Lab.

Okuma
Analysis/
ResearchCenter(JAEA)

Analysis of deposit/ adhesion

Analysis of fuel debris

Analysis of waste
Transportation inside the site▼Completion

Cold run and controlled area setting
Start of operation with radioactive materials

Design/Approval, etc.
Construction

2
TEPCO’sanalysisfacility

Start of operation (incl. cold run)
Design/Approval/Construction
Start of operation (incl. cold run)**indicates the place to be transferred to, but not corresponds to number of transfer.
(dashed arrow) may change depending on the operation status of other facilities.

Fig.20 Construction and operation schedule for fuel debris retrieval and new analytical buildings

Not transported off the site (priority on promptness)
Analysis as routine
work

Comprehensive analytical facility in TEPCO✓ Management of each facility and troubleshooting in the Fukushima Daiichi NPS✓ Expansion of data for fuel debris and solid waste (introduction of developed
analysis method)

Laboratory-#1 in Okuma Analysis
and Research Center (JAEA)

Laboratory-#2 in Okuma Analysis
and Research Center (JAEA)✓ Development ofprocessing/disposal technology for
Solid waste (except fuel debris)✓ Analysis of ALPS-treated water✓ Development for analysis
technique etc.

✓ Development of technology forcollecting, transferring and storingof fuel✓ Development for analysis
technique etc.

Analysis as technicaldevelopment

Permission to use
radioactive isotopes

Permission to use
nuclear fuelHot laboratories in Ibaraki prefecture (JAEA, NFD and NDC)
✓ Analysis that requires pretreatment techniques✓ Analysis/testing for a long period of time
✓ Analysis/testing that require specific device and equipment (hot celles
occupied)✓ Development for analysis technique etc.
Transported to off-site for works (priority over promptness)

Fig.21 Characteristics and roles of each facility for analysis
Not only the facilities for analysis in the Ibaraki area, but also the Radioactive Material Analysis
and Research Facilities to be operated in the area adjacent to the Fukushima Daiichi NPS are short80

of the human resources required to continue stable facility operation, and the securing andmaintaining of analytical engineers needs to be considered. In this respect, it is necessary toconsider in advance the qualities expected of analytical engineers in various analytical works, andto develop a plan so that the required roles are appropriately achieved. Since TEPCO must develop
human resources for fields where there is little experience in as short a time as possible, it isimportant to effectively work on developing analytical technicians with the cooperation of the JAEA
and Japan Nuclear Fuel Limited that have accumulated sufficient knowledge and experience on
the handling of α-nuclides and fuel analysis techniques. Personnel exchanges between TEPCO
and the JAEA and personnel acceptance from Nippon Nuclear Fuel Development Co., Ltd.
(hereinafter referred as to as “NFD”) to TEPCO have been ongoing.

4.4 Improvement of the quality of sample analysis results and use of nondestructive assay
4.4.1 Improvement of the quality of analysis results
Fuel debris contains difficult-to-measure nuclides, interfering elements, immiscible substances,
etc., and there are problems in pretreatment and measurement, such as uniform dissolution ofsamples and selection of isobar. Therefore, it is considered difficult to identify and quantify all
elements and isotopes down to trace components by analysis. It is also an important to have askeptical point of view to the analytical result of the samples in consideration of the impact of theerror factor. Monitoring data, sampling analyses, PCV internal/on-site investigation, analyses using
SA codes, and past knowledge and experimental results have been accumulated. As part ofverification of sample analysis results, through discussion and studies in light of existing findings,
such as results of analysis, investigation and testing, deriving consistent property evaluations will
improve reliability of analysis results, leading to higher quality of the analysis results.
To improve the analytical accuracy, the JAEA, the NFD, MHI Nuclear Development Corporation(hereinafter referred to as “NDC”), and Tohoku University have been cooperating to conduct
chemical analysis and structural analysis using the same samples since FY 2020. Consideration is
being given to analysis of TMI-2 debris in Ibaraki area offices using the latest technologies so as toexpand the fuel debris data in future.
TEPCO and the JAEA are already cooperating in implementing forensic activities that estimate
accident behavior and causes by comparing the results of sample analyses with simulation on
progression of meltdown and past scientific knowledge. Furthermore, as an international forum, theBSAF, BSAF-2, PreADES, and ARC-F, which have been implemented as projects of the
OECD/NEA, have come to an end, and the FACE project was launched in July 2022.
Since there are few personnel (analytical evaluators) who can design the analytical range anditems in anticipation of how to use the analysis results in advance, it is also important to makeefforts in increasing such personnel. Analytical evaluators are required to have the ability to (i)logically and accurately understand accident events from analytical results, (ii) appropriately

81

incorporate the evaluation results into the areas required for the decommissioning process(retrieval method, safeguards, storage/management, and processing/disposal), and (iii) provide
appropriate instructions for the following sampling. However, since it is difficult for individuals to
address these all abilities, TEPCO should take the lead in organizing an analysis and evaluationteam (One Team) by selecting researchers and engineers from domestic organizations withknowledge of fuel debris and decommissioning.
4.4.2 Sample analysis of fuel debris
The current sample analysis is mainly performed using electron microscopes after transporting
smear samples to facilities for analysis in Ibaraki area. Since the density, hardness, and other items
cannot be measured for micro or very small quantity of the samples, it is necessary to increase thesize and quantity of the samples in accordance with the progress of the fuel debris retrieval process.
Analysis is performed by using manipulators in analysis process in a hot cell, and in one facility,
analysis of about 0.5 to 1 samples per month will be conducted. Further, the amount to be used ineach hot cell is restricted for each nuclide that can be handled, and therefore, it is difficult to analyze
a large number of samples. Consequently, there is a large gap between the volume to be
retrieved/stored and the amount of samples for analysis.
Since fuel debris has heterogeneity, the analytical values vary depending on the sampled parts,and the situation is such that a sufficient amount of fuel debris cannot be analyzed, resulting in arange of uncertainty in evaluation. To increase the volume of good analytical results, regardless of
the restrictions on improving analysis quality and sample quantity, it is effective to not only focus
on increasing the volume in conventional sample analyses in hot laboratories but also to diversify
and expand other analytical and measurement methods, understand the disadvantages andadvantages of each item, and consider complementing them according to the intended use of theanalytical results, for a comprehensive evaluation. Depending on the application, it may be
worthwhile to consider methods that can only measure single items.
4.4.3 Use of sample analysis and non-destructive assay
One of the analysis and measurement methods that complements the results of sample analysis
is to evaluate the amount of nuclear fuel without destroying the sample using radiation, quantum,
etc. emitted, scattered, or transmitted from the sample (hereinafter referred to as "non-destructive
assay.”). Table 2 shows the relative comparison of the items of sample analyses performed inside
analysis facility and non-destructive assays performed out of the analysis facility and the numberof samples. Sample analysis can perform many analysis tasks, but the time required for analysis
is long, and the amount analyzed at one time is small. Although non-destructive assay can handle
fewer items, the measurement time is shorter than that of sample analysis, and a larger quantity
can be measured per measurement. Moreover, measurement can be performed with the object
stored in a sealed container to prevent the spread of contamination.

82

Table 2

Relative comparison of key specifications in sample analysis performed in the analysis
facility and non-destructive assay performed out of the analysis facility

Analysis of samples
performed in analysis
facility*

Non-destructive assay
performed out ofanalysis facility**

Time for analysis/ measurement

Long (△)

Short (〇)

Items for analysis/ measurement

Many (◎)

Few (△)

Amount per analysis/ measurement

Small (△)

Large (◎)

Generated (△)

None (〇)

Confinement during analysis andmeasurement

Unsealed

Unsealed or sealed

Dust prevention

Necessary

Necessary

Radiation shielding facility

Necessary

Necessary

Generation of liquid waste◎ : Excellent〇 : Good△ : Acceptable* ： The analysis will be conducted in a facility dedicated to analysis, such as a hotlaboratory suitable for dealing with fuel debris samples.
**：The facility will be used in the process from retrieving to storing fuel debris.
The analysis will be conducted in a facility not dedicated to analysis.

In addition to sample analysis in the analysis facility, if non-destructive assay limited to specificitems, such as quantitative nuclear fuel, is measured in the fuel debris containers, and it would
compensate for the small number of analyses and enable rapid determination of the amount of
nuclear fuel in the fuel debris. This will make it possible to maintain the subcritical state and moveon to the next process. At this time, it is desirable to keep the range of uncertainty in the propertiesof fuel debris as small as possible while increasing information about the sample, including thenumber of sample analyses and the coordinate information at the time of sample collection, toimprove the reliability of the data. In order to improve the accuracy of fuel debris characterizationand the safety in storing retrieved fuel debris, specific application methods of non-destructive assay
should be studied at the facilities used in the process from retrieval to storage of fuel debris.

83

5. Efforts to facilitate research and development
5.1 Significance and the current status of research and development
There are many difficult technical issues requiring research and development to promote thedecommissioning of the Fukushima Daiichi NPS from the perspectives of safe, proven, efficient,
timely, and field-oriented. At present, when trial retrieval of fuel debris is about to begin shortly, it isnecessary to accelerate research and development in consideration of the practical application fora gradual expansion of fuel debris retrieval and further expansion of fuel debris retrieval in scale.
In order to solve these technical issues, decommissioning research and development is being
performed by various industrial-academic-governmental institutions.
For application research and practical application research for decommissioning, theGovernment provides supports the R&D carried out by each organization to solve issues of highlydifficult ones through "the Project of Decommissioning and Contaminated/Treated Water
Management", and to promote basic and fundamental research and human resource development
by universities and research institutes in Japan and overseas through "The Nuclear Energy Science& Technology and Human Resource Development Project (hereinafter referred to as "WorldIntelligence Project")". TEPCO is engaged in technical development directly leads to practicalapplication. NDF considers R&D medium-to-long term plans, next-term R&D plans, and supports
the World Intelligence Project. With institutes involved as its members, moreover, NDF establishedthe Decommissioning R&D Partnership Council, which considers issues on information sharing onneeds and seeds for R&D, coordination of R&D in line with the needs of decommissioning work,and promoting cooperation in R&D and human resource development.
From FY 2022, JAEA plans to implement actions in accordance with the Phase 4 medium-tolong-term goals and plans. It is expected that JAEA will leverage its knowledge and experience in
R&D related to decommissioning of the Fukushima Daiichi NPS and play a significant role ininitiatives for characterization of fuel debris and R&D for waste management and analysis. The
R&D implementation system is shown in Fig. .
The R&D fields to be conducted at “the Fukushima International Research and Education Center”,
that will be established by the government in April 2023, are ① robots, ② agriculture, forestry
and fisheries, ③ energy, ④ radiation science, drug discovery and medical care, and industrial
use of radiation, and ⑤ collection and dissemination of data and knowledge on nuclear disasters,
and collaboration in R&D related to decommissioning is also expected. Therefore, NDF willconsider collaboration in the future with a view to outreach activities related to this Center’s R&D,
while also taking into account the basic plan6 for the promotion of R&D7.

Basic Plan for Research and Development for new industry creation (Provided by Cabinet Office, Governmentof Japan, August 26, 2022)
7 Basic Concept for the Fukushima International Research and Education Center (Provided by Reconstruction
Promotion Council, March 29, 2022)
684

Ministry of Economy, Tradeand Industry

Ministry of Education, Culture,
Sports, Science, and Technology

Project ofDecommissioning andContaminated/Treated
Water Management

Support for proposals forthe next R&D plan *6

Operating costsubsidy

Assistance

JAEA

NDF

Fund establishment corporation

Project
implementation*1(Constitution)
NDF, JAEA, the Tokyo Electric Power Company, IRID,
plant makers, related experts, the Ministry of Economy,
Trade, and Industry, the Ministry of Education, Culture,
Sports, Science, and Technology

Sharing and planning oftechnical development
information

Collaborative
Laboratories for
Advanced
Decommissioning
Science (CLADS)

Examination request
and support

OthersManufacturers,
etc. (including
overseascompanies)

Joint
Application,
etc.

TEPCO
Holdings

National Research andDevelopment Agency
Plants, manufacturers, etc.
Electric power companies, etc.

Companies in Japan andoverseas companies

Administrative
instructions

and joint research Project
implementation

A company
making a contract

Universities,
research
institutions,etc., inJapan

Project Management Operation

Basic research for decommissioning
Platform
Consignment

Cooperation

Secretariat*6 Consignment

Exchange of research needs
and seeds
Bridge-building for results

Subsidized company
International ResearchInstitute for Nuclear
Decommissioning

Foreigngovernmentorganization

Okuma Analysis andResearch Center

Cooperative relation

Participation

Cooperative relation

Naraha Remote Technology
Development Center

Decommissioning R&D
Partnership Council

Assignment

Secretariat*5
Assistance

Fukushima research anddevelopment department

Technical committees for decommissioning, etc.

Fund for Countermeasures for Decommissioning
and Contaminated/Treated Water Treatment

Assistance

Nuclear Energy Science &Technology and Human Resource
Development Project

Support *7

Participation

Joint
research

Overseas
universities
andresearch
institutions*1 The Decommissioning R&D Partnership Council is established in the NDF based on the determination by Team for Countermeasures for Decommissioning and Contaminated Water Treatment.
*2 The arrow drawn in a thick solid line indicates expenditures such as research expenses and operating expenses (excluding facilities expenses), the arrow drawn in a thin solid line indicates a cooperative relation, etc., and the arrowdrawn in a dotted line indicates the participation in the Decommissioning R&D Partnership Council.
*3 Some organizations such as JAEA are located at two or more places.
*4 Each organization has cooperative relations with foreign organizations based on MOU, etc., respectively.
*5 Although the subsidy for the World Intelligence Project for Nuclear S&T and Human Resource Development is delivered to JAEA, it is expressed as what is delivered to CLADS, to make it easier to understand.
*6 With regard to the Government-led Project of Decommissioning and Contaminated/Treated Water Management, based on the policy in the Mid-and-Long-term Roadmap or Strategic Plan and the progress situation of research anddevelopment, the NDF formulates a draft plan of the next research and development, and the Ministry of Economy, Trade, and Industry determines it.
*7 The NDF participates as a member in a steering committee of the World Intelligence Project for Nuclear S&T and Human Resource Development.

Fig. 22 Overview of the R&D implementation system related to the decommissioning ofFukushima Daiichi NPS

5.2 Key issues and strategies
5.2.1 the R&D medium-and-long term plan
In FY 2020, NDF and TEPCO developed the R&D medium-to-long-term plan overlooking theoverall research and development for about ten years for decommissioning and have updated it
every fiscal year since then. The R&D medium-to-long-term plan will be updated based on therevised Mid-and-Long-term Decommissioning Action Plan of TEPCO, the concept study for further
expansion of fuel debris retrieval in scale, and the progress in ongoing R&D.
In reviewing the R&D mid-and-long-term plan, TEPCO, Ministry of Education, Culture, Sports,
Science and Technology, Ministry of Economy, Trade and Industry, and NDF have participated in
the R&D planning meeting. Based on the discussions at the 10th Decommissioning R&D
Partnership Council held in February 2022, TEPCO, JAEA/CLADS, and NDF jointly analyzed andshared technical issues, including long-term issues exceeding ten years, to promote collaboration
between the World Intelligence Project and The Project of Decommissioning, Contaminated Water
and Treated Water Management, and have reviewed issues comprehensively and exhaustively.
The results will be incorporated into the R&D medium-to-long-term plan and the overall map of thebasic/fundamental research for reference.

855.2.2 Initiatives for The Project of Decommissioning, Contaminated Water and Treated
Water Management
5.2.2.1 The Project of Decommissioning, Contaminated Water and Treated Water
Management
The Ministry of Economy, Trade and Industry is providing support through The Project ofDecommissioning, Contaminated Water and Treated Water Management to solve technicallychallenging issues for decommissioning.
In the Project, since 2020, NDF has been participating in the secretariat to strengthen thefunctions of project planning and progress management, while TEPCO jointly applies for issuancein cooperation with research leadership and provides project management to incorporate
requirements in terms of actual site applicability.
This enhanced functionality has enabled the Secretariat to follow the progress of R&D, leading
to the smooth execution of projects and achieving intended results. In addition, TEPCO’s needs interms of actual site applicability have been incorporated into the Project, and the positioning of the
Project in TEPCO’s engineering schedule has been clarified.
5.2.2.2 Next-term R&D Plan
In order to support the Project, and based on the R&D medium-and-long-term plan, every fiscal
year, NDF is formulating the next-term R&D plan as the R&D to be carried out over the next two
years. The next-term R&D plan aims to solve issues related to fuel debris retrieval andprocessing/disposal of solid waste.
After adjustment and discussion with parties concerned at R&D planning meetings, the next-term
R&D plan is first deliberated on by the Fuel Debris Retrieval Expert Committee and Waste
Management Expert Committee, which are the committees at NDF, and then by theDecommissioning Strategy Committee. After this, it is summarized as an NDF proposal. This plan
was reported by the Ministry of Economy, Trade and Industry (METI) to the Team Meeting for
Decommissioning and Contaminated Water/Treated Water Management/Secretariat Meeting, and
the Project has been implemented accordingly.
In considering the next-term R&D plan, the R&D results have been evaluated to identify issues
whose level of achievement should be improved and emerging issues, as well as to identify newchallenges and organize technical issues with a view of the R&D medium-and-long-term plan.
When identifying issues, it is also important to identify them exhaustively, confirm whether eachissue is in line with the needs of TEPCO as the entity responsible for decommissioning, and aim
for R&D results to be utilized for TEPCO’s engineering.
In FY 2022, as a new initiative to develop the next-term R&D plan, a request for information (RFI)
was made to widely solicit information on technical issues to be resolved toward thedecommissioning of the Fukushima Daiichi NPS. In order to contribute to the consideration of thenext R&D plan, this is a request for the public to provide information on R&D themes, details of86

R&D (technical issues to be resolved and details of implementation), scale of R&D, potential joint
R&D destinations, and R&D fields.
5.2.2.3 Further research and development implementation system for The Project ofDecommissioning, Contaminated Water and Treated Water Management
The IRID has played a major role in research and development for decommissioning for about
eleven years since the time that the post-accident situation inside the reactors was unknown. In
particular, the IRID has established a good track record in internal PCV condition analysis throughits internal investigations, as well as development of analytical and estimation techniques forcharacterization of fuel debris, development of fuel debris retrieval equipment and storage
containers, and development of processing/disposal technologies for solid waste.
Meanwhile, as the engineering work by TEPCO progresses, the situation in the reactors and theneeds are gradually becoming clear. In addition, development is currently being promoted basedon the engineering work by TEPCO, which is a shift from joint activities through the Collaborative
Innovation Partnership. In light of changing environment, consideration is being given to a R&D
structure in preparation for IRID’s current continuity deadline after summer 2023.
Since it is still important to review R&D tasks from a broad perspective in The Project ofDecommissioning, Contaminated Water and Treated Water Management, evaluate the Project interms of actual site applicability and incorporate them into R&D. Accordingly, NDF plans to further
strengthen and restructure the functions related to R&D planning and proposals and efforts toensure operation quality in cooperation with TEPCO and other organizations concerned. On theother hand, for the projects that need to be succeeded to in the Project, the following issues must
be addressed if projects are to be implemented smoothly so as not to cause any problems, anddiscussions are being carried out by relevant organizations.
・The project executor when taking over the Project・Appropriate succession of hardware (tangible assets e.g. facilities and equipment) and software(intangible assets e.g. result products and technical information) necessary to continue R&D
・How to maintain and utilize the know-how accumulated by the subsidized projects
Regarding the outcome of the development that has been conducted through the Project, since
the decommissioning of the Fukushima Daiichi NPS is a national/social issue, it is important toestablish an easily accessible structure where organizations involved in the research anddevelopment for decommissioning can make effective use of the R&D results, including knowledge
obtained. Therefore, it is recommended that archiving in terms of information disclosure andknowledge sharing is promoted. In this case, the issues are to establish rules for the compilationand sharing of archival materials, establish a framework for the establishment/management ofarchival materials, and develop the management tools to be used.
TEPCO should be fully aware of the significance and role of each R&D project in all R&D
activities, from basic/fundamental research to practical application research. Then, while being
87

involved in R&D appropriately, under the management of the technology development by the D&D
Research & Development Center, TEPCO needs to be committed to decommissioning researchmore proactively including independent technology development by TEPCO. In doing so, it isnecessary to collaborate with the Toso Mirai Technology Company (hereinafter referred to as “thenew engineering company” established in October 2022.
5.2.3 Promotion of cooperation between decommissioning sites and universities/
researching institutions
5.2.3.1 The Nuclear Energy Science & Technology and Human Resource Development
Project
As the World Intelligence Project, the MEXT has been promoting fundamental/basic researchand human resource development activities, which contribute to solving issues such as
decommissioning of the Fukushima Daiichi NPS. The project is bringing together domestic andoverseas intelligence from universities/researching institutions, crossing barriers of the nuclear field,
and through close coordination and alignment including international joint research. JAEA/CLADS
implements this World Intelligence Project to strengthen cooperation between JAEA/CLADS anduniversities, and establish a system to implement medium-and-long term R&D and human resource
development, contributing to decommissioning more stably and continuously.
In soliciting applications for the current World Intelligence Project, JAEA/CLADS is using the“overall map of the basic/fundamental research”, which provides an overview of the entire
decommissioning process from contaminated water management to waste processing/disposal,
and identifies the R&D needs and seeds required. Since FY 2021, efforts have been made to match
decommissioning needs with research seeds, such as holding workshops with the participation of
TEPCO and companies involved in decommissioning. From FY 2022, the plan is to introduce
Research Supporters (RS) to maximize the use and outcomes of the results at thedecommissioning sites.
It is an important issue to directly apply the results of some basic/fundamental researchcontributing to problem-solving in on-site decommissioning, and it is important to promote better
matching needs from decommissioning site with seeds at universities/researching institutions andserve as a bridge to share outstanding research results obtained mainly in the World Intelligence
Project.
5.2.3.2 Collaboration between The Project of Decommissioning, Contaminated Water andTreated Water Management and the World Intelligence Project, and initiatives forbusiness-academia collaboration by TEPCO
To deepen the matching between needs and seeds and implement R&D for decommissioning
consistently from basic/fundamental research to applied practical application research, it isessential to promote collaboration between The Project of Decommissioning, Contaminated Water
and Treated Water Management and the World Intelligence Project. For that purpose, NDF andorganizations concerned should actively exchange and share information on the results of each88

project and work together on the use of the Decommissioning R&D Partnership Council andinitiatives to share future directions and issues shared at the Meeting.
TEPCO is also engaged in industry-academia collaboration efforts with universities (The
University of Tokyo, Tokyo Institute of Technology, Tohoku University, and Fukushima University) tounearth technological seeds that meet needs useful for decommissioning from a wide range of
research resources at universities, not only in the nuclear field but also in the basic/fundamental
research field.
The Government, JAEA/CLADS, NDF, TEPCO, and other organizations involved need to further
strengthen their cooperation for better matching needs with seeds and serve as a bridge to shareoutcomes.
5.2.3.3 Establishment of the centers of basic research/research infrastructure
In order to make the long-term decommissioning of the Fukushima Daiichi NPS proceed steadierin technical aspects, it is essential to work on developing R&D infrastructure and accumulatetechnological knowledge, develop fundamental technologies and collect basic data, building up
research centers, facilities and equipment, and human resource development. R&D for thedecommissioning of the Fukushima Daiichi NPS is an opportunity to practice state-of-art scienceand technology and the accumulation of such activities is expected to become a source ofinnovation.
The Collaborative Laboratories for Advanced Decommissioning Science of JAEA/CLADS(Tomioka-machi, Fukushima Prefecture) is working to enhance the base functions of JAEA/CLADS
by establishing a network of universities, researching institutions, and industry in Japan andoverseas to promote the R&D and human resource development in an integrated manner,
establishing the “Decommissioning research program based on development of research humanresources” in the World Intelligence Project, and starting the research, development, and humanresource development projects that connect organizations through a cross-appointment systemafter the establishment of a research/human resource development base (collaborative lab).
For research and development infrastructures as hardware, development and utilization of the
Naraha Center for Remote Control Technology Development of JAEA and maintenance of the JAEA
Okuma Analysis and Research Center (Radioactive Material Analysis and Research Facility) are
ongoing. In FY 2022, the Naraha Center for Remote Control Technology Development plans to
conduct a mock-up test of a device for trial fuel debris retrieval, and the Okuma Analysis andResearch Center has started the operation of Laboratory #1 of its analysis and research facility for
waste analysis.

89

6. Activities to support our technical strategy
6.1 Further strengthening of project management and improvement ofcapability required as a decommissioning executor
6.1.1 Significance and current status of project management
In order to smoothly proceed with the entire decommissioning project while harmonizing, it isnecessary to establish a management system in which the organizations involved in the projectwork together to achieve the goals and enhance their overall capabilities.
The individual work in each work area of a decommissioning project generally proceeds throughthe following processes: conceptual design, research and development, basic design, detailed
design, manufacturing, on-site installation, inspection, and operation. In addition, the NRA willconduct reviews and inspections, as necessary. In order to carry out such a series of processes
without omission or delay, it is effective to set up the major workflow defined in the long-term plan
as individual projects, which are management units of an appropriate scale. It is then important to
optimize the interrelationships and chronological relationships among the projects, and to proceedwith overall consistency under a sophisticated project management system so that the risks
inherent in the projects can be appropriately managed. From this perspective, TEPCO has beenworking to build and strengthen its project management system, which was reorganized in April
2020. Project-based organization management has been gradually established through two yearsof operation.
As difficult projects such as fuel debris retrieval will be implemented at full-scale in the future,
and TEPCO intends to take the lead in EPC 8 management, further enhancement of project
management capabilities is required.
As the decommissioning work is well underway, entering Phase 3 of the Mid-and-Long-term
Roadmap, it is anticipated that the projects to be handled will become more diverse, and interface
management between projects will become more complex, further increasing the level of project
difficulty. As a result, TEPCO's workload for project management is also expected to increase.
Leadership of the TEPCO management will become even more critical in securing personnel overthe long term, for example, by prioritizing work and peak work shifting to equalize the workload andincreasing the number of personnel if the workload still cannot be supported.
Examples of key initiatives up to FY 2022 include: strengthening the authority of project
managers through organizational restructuring, process management using dedicated software(P6), establishing and operating a risk monitoring system (risks are quantified using risk
management sheet - risks are mapped on two axes, frequency of occurrence and impact, and risk
trends are monitored regularly at meetings with the management's attendance.), strengthening
project management based on partnership agreements with overseas companies with knowledge

8

E: Engineering, P:Procurement, C:Construction90and experience in decommissioning projects, improving the level of safety and quality, anddevelopment of a forward-looking plan (Mid-and-Long-term Decommissioning Action Plan) .
6.1.2 Key issues and strategies to be strengthened in the future
6.1.2.1 Safety and Operator's Perspectives and promulgating the "Safety First"
In April 2021, TEPCO received an order from the Nuclear Regulation Authority (NRA) to prohibit
the transfer of specified nuclear fuel materials due to non-conformities in the protection of nuclear
materials at the Kashiwazaki-Kariwa Nuclear Power Station (hereinafter referred to as"Kashiwazaki-Kariwa"). As a result, TEPCO's nuclear regulatory inspection response category
became Category 4 ("the objectives of the activities in each monitoring area are satisfied, but there
is a prolonged or significant deterioration in the safety activities conducted by the operator"), andmany inspections will now be conducted under the supervision of the NRA.
The operation of Fukushima Daiichi NPS differs from that of the Kashiwazaki Kariwa in terms of
the form of business, and as for the management system, the full-scale project management has
been implemented in the Fukushima Daiichi, which is also different compared to KashiwazakiKariwa. In February 2022, on the other hand, a non-conformance event occurred, where
information on the failure of the seismometer installed on a trial basis in the Unit 3 reactor buildingof the Fukushima Daiichi NPS was not shared within the organization, and it was not fixed/restored
for a long period of time. Although there were no issues with work safety or exposure, etc., a seriesof events are receiving severe external criticism. At the Fukushima Daiichi NPS, the management
themselves are engaged in conversation with all site personnel to understand the organizational
issues behind the events.
In order to establish safety as part of the organizational culture, so that is not just a slogan, it isinsufficient to just ask employees to prepare themselves, and instead each and every employee
needs educational materials and opportunities to learn about safety in a systematic way. Moreover,to regain the trust of the public, it is important for TEPCO to continuously improve and promotemeasures for preventing nonconformities, especially those that could lead to environmental
impacts, personal injury, and radiation dispersion, as well as to disseminate information and build
systems that incorporate the perspective of the local community. Frequent occupational accidents,
human errors (HEs), and system failures will cause the community and society to lose trust.
Especially with respect to occupational accidents, since many workers at Fukushima Daiichi arelocal resident, continued occupational accidents can cause anxiety not only for on-site workers but
also for their families. Ensuring “a safe workplace” is the responsibility of the owner. TEPCO willfurther refine its on-site capabilities as an owner and aim for a "three zeros" workplace with zero
occupational accidents, zero HEs, and zero system failures.

916.1.2.2 Owner's engineering capability
In projects with mature technology, precise performance requirements, and large scale, such as
the construction of nuclear power plants, waterfall engineering9 is usually used. However, sincefuel debris retrieval is an approach in which no one has experience, the target settings and required
specifications from TEPCO, the executor of the decommissioning project, are not always clear
when undertaking engineering work, and the degree of performance requirement settings, physicalfeasibility of methods and equipment, and performance assurance must be through trial and error.
Therefore, in addition to “the sequential approach” that addresses “work in the initial stage” andthen rolls out the information gained to the next stage, the operation executor’s performancerequirements, the establishment of the supply chain functions, and its engineering process should
be iteration approach-based10, to some extent.
In iterative engineering, the contract between the project executor and the supply chain is notconventional, so TEPCO, as a project executor, is strongly required to "make a judgment onengineering and is responsible for the results”. To achieve this, as the project executor, TEPCO as
the owner must improve its owner engineering capability. The owner's engineering capability here
refers to the capability required of TEPCO itself as a site owner11 and a license holder, specifically,
it is a capability that consists of both project management capability and technical capabilities
based on safety and operator’s perspectives.
Fuel debris retrieval, in which the applicable technology, environment, and target objects are all
unknown, is not work like designing and constructing a nuclear power plant, where the finishedproduct is delivered with a performance guarantee. Therefore, unless TEPCO, the executor of the
project, bears the business and technical risks ultimately, there is a risk that the performancerequirements will be unlimited.
(1) Project management capability
The decommissioning of the Fukushima Daiichi NPS must be carried out reliably over a long
period of time under changing site conditions, and it will be difficult to cope with conventional
contracts, especially for high-risk project work such as fuel debris retrieval. Therefore, it isnecessary to prepare a contract method based on a new concept, in which both the contractor andthe recipient cooperate, share the contractual risks, and aim for the agreed-upon goals. In terms ofprocurement, instead of one-way “Buying” from an ordering party to an order-receiving party, both

It is a method of increasing the accuracy of the design in stages, from conceptual study to basic design and thento detailed design. Since the process proceeds in a single direction from upstream to downstream, it has theadvantage of easy control of budget, process and resources (personnel), but it also has the disadvantage of not
being able to go back once the next phase is underway. It is called the waterfall type, because it resembles awaterfall where water falls from the top to the bottom.
10 A method of gradually increasing the percentage of completion of engineering by finding the next result basedon a certain result and repeating this cycle.
11 An owner here has three positions of a party responsible for disaster occurrence, a specified nuclear facility
licensee, and a facility owner. TEPCO is executing the decommissioning project from these three positions. (Aproject executor of decommissioning)
992

parties should bear in mind the concept of “Acquisition” of the final result by “Making”, withconsideration of all steps from development, manufacturing, to even operation/maintenance.
To deal with such Making-based projects, in addition to improving the engineering capability,
such as the ability to materialize specifications, it is necessary to have project management
capability with a focus on “Acquisition of the final result”.
Based on the shared awareness that conventional Buying-oriented project management alone
is not enough to properly control projects with large uncertainties such as fuel debris retrieval,
TEPCO and NDF are benchmarking the acquisition management 12 ,13 as adopted by the U.S.
federal government as a precedent to further develop current project, and are actively learning themethodology with the cooperation of external experts starting from FY2017, and currently
customizing it to fit the decommissioning project of the Fukushima Daiichi NPS.
(2) Engineering capability based on safety and operator’s perspectives
In the past, the construction of nuclear power plants was achieved on-time, on-budget, and onperformance by placing bulk orders with companies with extensive construction experience.
However, no company has experienced the decommissioning of a plant that has experienced ameltdown like the Fukushima Daiichi NPS. Especially, fuel debris retrieval is extremely technicallychallenging, and it is not easy to accomplish with only one company’s technology. It is necessary
to call upon each company's unique and top technologies and establish a single system. To achievethis, TEPCO must have more technological capabilities than before, i.e., the engineering
capabilities being able to judge the merits and demerits of individual technologies ("insight”) andthen integrate them into a system to achieve the desired performance. Through the insourcing thatthey are promoting, TEPCO aims to improve its ability to make engineering judgments on individual
technologies, enhance capabilities for integration as a system, and reduce technical risks.
In addition, the situation of Fukushima Daiichi NPS has changed significantly from before theaccident, so the ability to think about things from the perspective of the site (on-site capability) is
particularly important. Specifically, the following capabilities should be developed based on athorough knowledge of the functions and performance of the equipment to be acquired;

Acquisition management is a project management method adopted (and legislated) in the U.S. federal
government budgeting process in the 1990s and has been continuously improved. It aims at acquiring outcomes(products, structures, and deliverables) using scientific and systematic management techniques based on reliable
data. This method differs significantly from conventional in that it breaks down work in the Work Breakdown
Structure (WBS) into the elements of outcomes (products, structures, and deliverables) to be obtained rather thantasks. In addition, by accumulating the costs of each decomposed element based on the planning process andvisualizing the progress of the project, it becomes possible to appropriately identify the gap between the plan andthe actual situation, to grasp the risk at an early stage, and to take countermeasures.
13 In acquisition management, acquisition and procurement are defined as follows and adequately used dependingon the case. Acquisition refers to acquiring the value and capability related to specific equipment and otherdeliverables throughout their lifecycle, from development, manufacturing, and operation to maintenance, toachieve a specific goal or objective. However, a part of this acquisition flow is sometimes contracted to an externalorganization at each phase, such as development and manufacturing, and the gaining of specific elements on
this contract basis is called procurement. In other words, acquisition consists of several procurements(deliverables based on contracts).
1293 in the design phase, ability to develop specifications to ensure that a given function can be
performed over its life cycle (from installation, verification, operation to maintenance) under onsite operating conditions (operating environment, with/without interfering objects, etc.),
 in the on-site operation phase, ability to assess the latest on-site conditions, identify potential
risks (e.g., accidents involving personnel, procedural errors, etc.) in conjunction with thecontractor, and take appropriate risk measures to ensure safety and quality on the operation
site, and
 in the event of an emergency, ability to troubleshoot problems by TEPCO employees themselves,
even without support from partner companies.
6.1.2.3 Securing and developing human resources
6.1.2.3.1 Securing and developing human resources for smooth implementation of
decommissioning projects
In addition to the fact that the decommissioning project of the Fukushima Daiichi NPS is an
unprecedented task for which nobody has experience, it is necessary to systematically secure anddevelop human resources in anticipation of the expansion of operations in line with the progress ofthe fuel debris retrieval plan. Specifically, based on the Mid-and-Long-term Decommissioning
Action Plan and mid-to-long-term business outlook with a view to subsequent businessdevelopment, it is desirable to develop a staffing plan that includes the required skills and qualities
and headcount as well as an organizational development plan that outlines tactics to achieve them,and implement measures to increase personnel motivation. Of these, human resource
development is particularly time-consuming. Thus, it is also necessary to reduce inefficient
operations and use limited human resources effectively. In the future, a higher level of engineeringand expertise will be required to achieve more technically challenging goals than in the past, suchas selecting methods for fuel debris retrieval and designing new systems and facilities. Therefore,
in the mid-to-long-term staffing plan, it is desirable to anticipate the required headcount in eachtechnical field and when they are needed, including personnel with more advanced expertise inaddition to those in each job category that will be needed in the future.
6.1.2.3.2 Fostering the next generation who will be responsible for the futuredecommissioning of Fukushima Daiichi NPS
In order to continue decommissioning of the Fukushima Daiichi NPS for a long period of time
and to continue R&D activities necessary for that, it is essential to train and secure future
researchers and engineers, and ensure technical transfer, as well as it is important for industrialacademic-governmental institutions, as a whole, to steadily promote efforts according to each levelof higher and secondary education.
For students in higher education, it is fundamentally important for the industry and higher
education institutions to cooperate and continuously implement activities to promote understandingof the nuclear industry, and constantly produce young researchers/engineers from these higher
education institutions. In particular, the World Intelligence Project by MEXT and JAEA/CLADS has
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introduced a system in which students and young researchers are made to be aware ofdecommissioning as an important research area, and is engaged in decommissioning research.
The World Intelligence Project's mechanism and implementation have produced some results, andhuman resources have been activated, with graduates being engaged in decommissioning-related
projects. Hereafter, it is important to implement this project so that the perspectives ofdecommissioning sites in TEPCO and those of the activities in higher education institutions can be
more aligned.
For students in the stage of secondary education, it is important to introduce appealing pointsof engaging in the nuclear field including decommissioning, and to make efforts to attract theirtechnical interests with a focus on decommissioning, as well as to increase their understanding ofdecommissioning and reconstruction of Fukushima Daiichi NPS, and in a broad sense, of the
career path in science and technology fields. In addition, NDF hosts “student sessions” for highschool students, etc., to give thought to the reconstruction of Fukushima along with the International
Forum on the Decommissioning of the Fukushima Daiichi NPS (hereinafter referred to as“International Forum”). In 2022, as in 2021, workshops are being held to discuss a vision of the
future in the Futaba area in 2050, based on prospects derived from statistical data on the Futaba
area, the status and plans for decommissioning, and information on human and natural resourcesin the entire Hamadori area. Through these efforts, high school students are given an opportunity
to think about activities to achieve both decommissioning of the Fukushima Daiichi NPS andreconstruction, enabling them to increase their awareness that decommissioning is an important
issue in reconstruction of local communities, and foster interest in and willingness to contribute todecommissioning and reconstruction efforts. Such activities have achieved some positive results.
Institutions concerned are continuously required to promote and strengthen their efforts to secureand develop human resources for the next generation according to their respective roles and levels.
6.1.2.3.3 Dissemination of basic knowledge and promoting the people's understanding fordecommissioning and radiation safety involved in decommissioning
It is important for many citizens and local residents to acquire basic knowledge of the accident
and decommissioning, disaster response, radiation safety, and food safety related to the
Fukushima Daiichi NPS from the perspective of future resilience of the whole country. This isbecause it will serve as basis for discussions on decommissioning, and related radiation safety,
etc., based on accurate information and for promoting public understanding. In addition, although
it is not directly aimed at fostering human resources who will play a leading role in the nuclear fieldin the next generation, it is also an aspect of indirectly broadening the range of human resources
who are interested in not only in the nuclear field but in science in general. Particularly in the fieldof nuclear energy, it is necessary to learn about the relationships in local communities and society
through various opportunities according to the development stage of children, as well as to acquire
knowledge and experience on nuclear energy and decommissioning. To do so, since it is importantthat children take an interest through the knowledge and experiences of adults around them, such95

as teachers and parents. Therefore, it is important to further spread knowledge on nuclear energy
and decommissioning based on scientific evidence, which to a wide range of people including those
involved in primary education institutions.

In this regard, the government is promoting thecontinuous expansion of on-site classes and the facilitation of the use of supplement books about
radiation, based on the “Action Plan for the Steady Implementation of the Basic Policy on the
Disposal of ALPS-treated water” (formulated on December 28, 2021, and revised in August 30,2022). NDF also holds workshops for local students to discuss decommissioning andreconstruction as described above.

6.2 Strengthening international cooperation
6.2.1 Significance and the current status of international cooperation
In recent years, nuclear reactors and nuclear fuel cycle-related facilities built at the dawn of theuse of nuclear energy have reached the end of their operational life, and decommissioning of thesefacilities is in full swing in many countries. Each country continues to face challenges such astechnical difficulties what is called "unknown unknowns (don't know what we don't know)", longterm project management, and securing large amounts of funding.
In order to steadily proceed with the decommissioning of the Fukushima Daiichi NPS, which
deals with difficult engineering issues, it is important to learn lessons from precedentdecommissioning activities, etc. and apply them to the decommissioning of the plant as a risk
reduction strategy, and to utilize the world's highest level of technology and human resources, i.e.,
to gather and utilize the wisdom of the world.
To bring together the wisdom of the world, it is important to maintain and develop theinternational community's continuous understanding, interest, and cooperation in decommissioning.
Therefore, it is important to promote decommissioning in a mutually beneficial manner that is open
to the international community by gaining the trust of the international community and disseminating
accurate information on the progress of decommissioning, etc., and by actively and strategically
returning to the international community the knowledge and other findings gained through theaccident at the Fukushima Daiichi NPS and decommissioning.
Specifically, it is important to promote bilateral cooperation in line with the circumstances of eachcountry and to utilize the framework of multilateral cooperation through the IAEA and OECD/NEA.
Japan has been holding an annual dialogue and establishing a conference body to share
information with other countries as an intergovernmental framework. Moreover, each of the relevant
domestic organizations has concluded cooperative agreements and arrangements with relevant
overseas organizations, and has disseminated information at international conferences. NDF has
been working on disseminating information on decommissioning through speaking at majorinternational conferences. By securing the trust of the international community and promoting
mutually beneficial decommissioning, we are trying to maintain and develop the international
community's continuous understanding and interest as well as cooperative relationships.
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In addition, in the course of the above-mentioned international cooperation, due to the global
outbreak of COVID-19, many meetings and events related to IAEA, OECD/NEA, etc. are held
online. NDF has also been actively utilizing the online systems and other means and ensuringcontinuous opportunities for information exchange to gather the world's wisdom, maintain andenhance the international society's continuous understanding and interest, and maintain anddevelop cooperative relationships with international community, such as the exchange of views withinvited overseas experts in previous years and the holding of annual meetings withdecommissioning-related organizations in other countries online. In the future, it is important tofurther expand the opportunities for communication with other countries by taking advantage of theexperience gained so far.
6.2.2 Key issues and strategies
6.2.2.1 Integrating and giving back the wisdom and knowledge from around the world
In moving forward with decommissioning, Japan has received various kinds of assistance fromforeign governmental organizations and experts, through the dissemination of information on
issues related to decommissioning to the international community and participation in international
joint activities. About eleven years have passed since the accident, and it is important to deepen
the mutually beneficial relationship while also working to return the know-how and lessons
accumulated so far to the international community. The situation of the Fukushima Daiichi NPS andthe knowledge obtained have been disseminated through the international joint activities andconferences mentioned above, and it is necessary to promote these activities continuously. In
addition, it is desirable for Japan to actively provide information on the accident at the Fukushima
Daiichi NPS, activities, and achievements toward decommissioning to countries other thanadvanced nuclear nations in cooperation with international organizations.
The difficulty in traveling to and from other countries due to the pandemic outbreak of COVID-19
is an obstacle to the continuation and enhancement of such mutually beneficial relationships.
However, it is important to secure opportunities for communication and work to maintain anddevelop relationships by utilizing online systems and other means so that the unprecedented
situation, not limited to the COVID-19, does not dilute relationships with relevant organizations,experts, and international organizations in other countries.
In addition to disseminating information on the current status and challenges of thedecommissioning to the world through a series of the International Forums, NDF has collected thewisdom including lessons learned and technologies derived from decommissioning around theworld,. It is important to continue to make the International Forum an effective opportunity to gather
and return wisdom from all over the world by using the online system, even in the situation where
direct participation from other countries is difficult. On the other hand, in light of the epidemic
situation of the COVID-19and possible changes in the way measures are taken to prevent the
spread of infection, NDF will gather and return wisdom and knowledge by using effective methods
with a view to proactively securing opportunities for face-to-face communication.
97

As the engineering of Fukushima Daiichi NPS is in full swing, it is important to grasp the latest
status of excellent technologies and human resources in the world and to utilize them effectively.
In this context, TEPCO has been actively engaged in technological exchanges with overseas
private companies. For instance, the robot arm for the trial retrieval of fuel debris from Unit 2 wasdeveloped by a British company and is currently undergoing training in Japan. It is necessary for
TEPCO to continue to keep abreast of the latest information from around the world, including thesituation in the private sector, and to engage in continuous communication with these privatecompanies, sharing information on the progress of decommissioning work and forming anenvironment in which the necessary technologies can be accessed when needed.
6.2.2.2 Maintaining and developing the international community's understanding of andinterest in decommissioning and cooperative relationships
In order to mobilize the wisdom of the world for the decommissioning of the Fukushima Daiichi
NPS, it is important to maintain and develop the understanding, interest, and cooperative
relationship of the international community. Until now, an online system has been used to maintainexchange opportunities. However, considering that the face-to-face activities of the international
community is returning, it is essential to maintain and develop cooperative relationships with
relevant organizations and international organizations, with a view to restoring face-to-faceinteractions as well as online exchanges.
It is important for the government and other domestic organizations to ensure transparency of
information on decommissioning and continuously disseminate accurate information in order tomaintain, increase understanding of the international community, and build a trusting relationship.
Regarding information dissemination, about eleven years have passed since the accident, theinterests of the recipients of the information have changed since the time of the accident, and there
are some gaps between countries in the amount of knowledge and information that are the baseof understanding. For this reason, consideration should be given to providing easy-to-understandinformation not only for experts but also for non-experts, devising ways of providing explanations
that consider the level of understanding of the recipients by effectively using videos and illustrations
and disseminating information in languages other than Japanese and English. It is also important
to deepen the understanding of information recipients by disseminating and accurately visualizing
information on the current status and issues related to decommissioning, paying attention to theirlevel of interest and understanding, as this will eventually lead to building a trusting relationship.
In this way, in participating in international joint activities, with the steady implementation of
decommissioning, which is Japan’s top priority, as a premise, it is necessary to work in such a waythat the interests of the international community can also be secured. Disseminating accurate
information continuously is also important as a means to return knowledge obtained indecommissioning to the international community. From the aspect of returning the results, it is also
becoming more important to maintain the level of interest by responding to the changes in the98international community, such as the growing interest in not only the accident and decommissioning
itself but also the application to other issues.
Furthermore, in response to changes in the global energy situation in the wake of the recent
Ukraine crisis, many countries have been reviewing their energy policies. Even under suchcircumstances, it is necessary to maintain smooth cooperative relationships with other countries
toward the decommissioning of the Fukushima Daiichi NPS while gaining an accurate
understanding of the updated status in the countries concerned.
It is important for NDF to disseminate and collect information accurately and in accordance with
the interests of recipients through various opportunities, and to return to the international
community the knowledge gained in the course of decommissioning.

6.3 Local community engagement
6.3.1 Significance and the current status of local community engagement
6.3.1.1 Basic concept
The fundamental principle for the decommissioning of the Fukushima Daiichi NPS is "Balancing
between reconstruction and decommissioning". In the areas where the evacuation order has been
lifted, progress toward reconstruction is gradually being made, not only by the return of residents
and the resumption of business activities, but also by the promotion of migration and settlementfrom outside the area and new investment. While giving top priority to further reducing risks to thesurrounding environment and ensuring safety, It is necessary to strengthen communication andpromote coexistence with local communities to gain the trust of the community. Decommissioning
should not be allowed to have a negative impact on the reconstruction process due to anxiety anddistrust of decommissioning, in other words, decommissioning should never be a hindrance toreconstruction efforts.
Therefore, it is important to deepen the understanding of local residents and reassure them about
the decommissioning through interactive communication: not one-way dissemination of information,
but sincere listening to the concerns and questions of local residents and promptly providing themwith accurate information in an easy-to-understand manner to eliminate them. In addition, toaccomplish the decommissioning over a very long period of time, the continuous cooperation ofcompanies, especially local companies, is essential. At the same time, the participation of local
companies in the decommissioning project is an important pillar of TEPCO's contribution to thereconstruction of Fukushima, as it will not only revitalize decommissioning-related industries in theregion and create employment and technology, but also lead to the spread of the results to otherregions and industries.
6.3.1.2 Specific measures under the current situation
Based on their "Commitment to the people of Fukushima to achieve both reconstruction anddecommissioning” established in March end, 2020 (hereinafter referred to as “Commitment”),
99TEPCO has summarized their efforts for the accumulation of decommissioning work into thefollowing 3 categories: “① Increased participation of local enterprises”, “② Support for local
enterprises to step up” and “③ Creation of new local industries”, and has started to implement
them in a phased manner.
With regard to the efforts ① and ②, in cooperation with the Fukushima Innovation Coast
Framework Promotion Organization and the Fukushima SOSO Reconstruction Promotion
Organization, TEPCO has set up and are operating a joint consultation service to support matching
between local companies interested in participating in decommissioning projects and prime
contractors who are considering placing orders with local companies. In addition, it is also
conducting a survey of the needs of both prime contractors and local companies regarding humanresource development, and has started joint research with several universities. Moreover, thecontents of the "Medium- to-Long-Term Outlook in the Decommissioning" prepared in September
2020 are being updated as necessary to reflect the progress of decommissioning work, and briefing
sessions are being held for local commercial and industrial organizations, and local contractors aswell as the prime contractors, paying close attention to the spread of the new coronavirus infection.
In addition, with regard to the effort ③, in order to build an integrated decommissioning project
implementation system locally, from "development and design" to "manufacturing", "operation,""storage," and "recycling", TEPCO plans to establish and operate several new facilities in the 2020s,
so that technologies and products of relatively high difficulty and importance, which have beenordered outside Fukushima Prefecture, including overseas, can be completed in the Hamadori
region. In particular, for "development and design" to "manufacturing", TEPCO aims to create local
employment, develop human resources, and build industrial and economic infrastructure byestablishing a joint venture with partner companies and working closely with local businesses(announced on April 27, 2022). In October 2022, as a joint venture for fuel debris retrieval, a newengineering company was established (announced on October 3, 2022)
6.3.2 Key issues and strategies
6.3.2.1 Communication issues and strategies
Misunderstandings, concerns, and rumors caused by the inappropriate dissemination of
information on the decommissioning of the nuclear power station will lead to a loss of reputationand trust in the decommissioning of the nuclear power station not only in the local community but
also in society as a whole, which will not only delay the decommissioning of the nuclear power
station but also hinder the reconstruction of Fukushima. For this reason, TEPCO needs tocontinue to take various measures to promptly communicate the current status ofdecommissioning in an easy-to-understand manner. In this regard, while the impact of the newcoronavirus infection is expected to continue for the foreseeable future, TEPCO will make active
use of tools such as virtual tour programs and online conference systems, and it is also important
to strengthen communication that is possible even in non-face-to-face and non-contact situations,such as by further enhancing photo and video content.
100Furthermore, the government, NDF, and TEPCO must work to build trust with local communities
by providing information more carefully under appropriate coordination. Therefore, capturing
opportunities to hold round-table talks and join local meetings/events, it is necessary to have directinteraction with local communities. Efforts should also be made for two-way communication by
conversation, including listening to their concerns and questions carefully through events such as
International Forums, and to deliver accurate information in an easy-to-understand and carefulmanner. In addition, it is important that the community, TEPCO, the government, NDF, and relatedorganizations take these opportunities to deepen their knowledge together in the various changing
circumstances.
In particular, some remain opposed to the disposal policy of the ALPS-treated water, and local
governments and related organizations are strongly urged to provide accurate information, foster
understanding, and take all possible measures to prevent rumors. For that reason, the governmentis implementing the measures including dissemination of information and reputational damage
prevention based on the “Action Plan for Steady Implementation of the Basic Policy on the Disposalof ALPS Treated Water” (formulated on December 28, 2021, and revised on August 30, 2022).
TEPCO has been making efforts to suppress reputational damages stated in the “TEPCO
Holdings’ Action in Response to the Government’s Policy on the Handling of ALPS Treated Waterfrom the Fukushima Daiichi Nuclear Power Station” (released on April 16, 2021). It is important tocontinue to do its utmost to foster understanding of local communities, and to build a relationshipof trust.
6.3.2.2 Issues and strategies related to the creation of a regional industrial and economic
base through decommissioning
TEPCO is making various efforts to realize the "Commitment", but these efforts will not produce
visible results immediately and will require a certain period of time. For the effort of "③ Creation of
new local industries", construction and operation of several new facilities in the 2020s andestablishment of joint ventures with partner companies were announced on October 3, 2022. It isnecessary to steadily promote and strengthen these effort, because they are relatively large-scale
investment and are expected to have a great economic impact on the Hamadori area. However, as
advanced techniques are required to produce high-performance products, the issue is how toconnect them to promoting active participation in local companies.
Therefore, for the time being, it is important to continue and strengthen the current activities in a
credible manner, including "① Increased participation of local enterprises" and "② Support for
local enterprises to step up". It is also important to carefully explain to local governments,
commercial and industrial organizations, and other organizations concerned the location and scaleof new decommissioning-related facilities, the schedule from construction to operation, and thestatus of considering engagement with local communities in terms of employment, cooperation andorder placement, and to proceed with the activities while gaining understanding and cooperation.

101

With the understanding of prime contractors, it is necessary to consider specific methods ofordering and contracting that will make it easier for local companies to receive orders, and to
implement these methods on a trial basis. As a result of interviews conducted with local companies
in 2020, it became clear that local companies do not necessarily want to be the main contractor,
but tend to want to enter the market as a subcontractor to gain technology and experience. Afterproperly understanding the intentions and needs of these local companies, a scheme can beestablished to benefit both parties by not only approaching local companies, but also encouraging
existing prime contractors to place orders with local companies, including technical guidance. This
will contribute to the promotion of orders from local companies by adopting methods that are
beneficial to both parties. In particular, it is also important to indicate that TEPCO will work together
with the local community and Fukushima prefecture for the long-term decommissioning work in the
future. For example, by considering initiatives that will enable local companies to receive constantand a certain scale of orders, after analyzing the details of procurement and the characteristics of
local companies with relevant organizations while keeping in mind the decommissioning work. At
the same time, with regard to human resource development, the Fukushima Decommissioning
Engineer Training Center of the Fukushima Nuclear Energy Suppliers Council, which wasestablished in 2018, and has been providing education of radiation protection and special education
on specific matters such as low-voltage electricity handling, should be used to provide the training.
In parallel, specific studies and preparations for training specifically for local companies should beaccelerated. It is important to steadily promote these various efforts while responding to changes
in the situation as appropriate, and to build a foundation for local industry and economy throughthe decommissioning project and to develop local companies and human resources.
In addition to research and development related to decommissioning, as companies from outside
the region move into the region and provide technical guidance to local companies, the number ofengineers and researchers visiting and staying in the region is expected to increase. Therefore, itis necessary to establish the necessary environment and support system so that such external
personnel can integrate into the local community and play an active role as a member of it. In
particular, it is necessary to take into consideration a wide range of functions such as daily life andeducation so that not only single people but also families can live together with peace of mind. In
this regard, as well as promoting the return of residents, Fukushima prefecture opened "Fukushima
12-municipality Migration Support Center" that helps people move and settle in the 12
municipalities, mainly from outside the prefecture for accelerating the reconstruction of theevacuated areas by promoting wide-area migration and settlement. The prefecture has been
disseminating information to people throughout the country who are interested in migration andproviding various types of support to those who wish to move to the 12 cities, towns and villages.
It is also important to consider the possibility of collaboration and cooperation with these local
initiatives.
To steadily promote these efforts for coexistence with local community, it is essential tostrengthen the organizational structure within TEPCO and to have close cooperation between each102

department. TEPCO has been reorganizing itself to set up specialized departments for regional
symbiosis, and efforts to promote local industries through decommissioning are gradually moving
forward, and gaining a certain level of recognition from the local community. While keeping thistrend advancing steadily, it is important to further strengthen internal efforts as necessary forpromoting local industries.
Moreover, it is necessary to further strengthen cooperation and collaboration with local
governments, including Fukushima Prefecture, and local related organizations, including the
Fukushima Innovation Coast Framework Promotion Organization and the Fukushima SOSO
Recovery Promotion Organization, which are operating a joint consultation service and co-hosting
matching business meetings. NDF will provide appropriate support to TEPCO's efforts for regional
symbiosis, and will strive to strengthen cooperation and collaboration with local governments andrelated organizations.

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