Technical Strategic Plan 2021 for Decommissioning of
the Fukushima Daiichi Nuclear Power Station of Tokyo
Electric Power Company Holdings, Inc.

Overview

October 29, 2021

Nuclear Damage Compensation andDecommissioning Facilitation Corporation

Table of Contents
1

Introduction................................................................................................................................ 2
Structures and systems toward the decommissioning of the Fukushima Daiichi Nuclear
Power Station ............................................................................................................................ 2
The Technical Strategic Plan .....................................................................................................42

Concept for reducing risks and ensuring safety in the decommissioning of the Fukushima
Daiichi NPS ............................................................................................................................... 5
Basic policy for the decommissioning of the Fukushima Daiichi NPS ......................................5
Concept of reducing risks caused by radioactive materials ......................................................5
Approach to ensuring safety during decommissioning ............................................................10

3

Technological strategies toward decommissioning of the Fukushima Daiichi NPS ............... 14
Fuel debris retrieval .................................................................................................................14
Waste management .................................................................................................................33
Contaminated and treated water management .......................................................................44
Fuel removal from spent fuel pools .........................................................................................51

4

Analysis strategy for promoting decommissioning ................................................................. 54
Uncertainty of fuel debris, etc. and importance of analytical results .......................................54
Three elements of analysis strategy ........................................................................................54
Current status of establishing an analysis system and strategy .............................................54
Improvement of the quality of analysis results, diversification and expansion of analysis
methods................................................................................................................................... 55

5Efforts to facilitate research and development........................................................................ 58
Significance and the current status of research and development .........................................58
Key issues and strategies ........................................................................................................59

6

Activities to support our technical strategy ............................................................................. 63
Further strengthening of project management and improvement of capability required asa decommissioning executor .................................................................................................. 63
Strengthening international cooperation ..................................................................................67
Local community engagement .................................................................................................70

List of Acronyms/Glossaries ........................................................................................................... 74

1 Introduction
At present, contaminated water management, which required urgent measures immediately
after the accident, have been stabilized, including the reduction of the amount of contaminatedwater generated and the completion of the treatment of stagnant water in the buildings (other than
the reactor buildings of Units 1-3, the main process main building, and the high-temperatureincinerator building). Fuel removal from spent fuel pools (hereinafter referred to as “fuel removalfrom SFP”) has been completed in Units 3 and 4, the decommissioning work is steadily in progress.
In addition, countermeasures against disasters such as earthquakes and tsunamis are progressing.
During the earthquake that struck off the coast of Fukushima Prefecture on February 13, 2021, thewater level in the primary containment vessels of Units 1 and 3 dropped, and the medium- and lowconcentration tanks and storage tanks for stagnant water in Units 5 and 6 slid (shifted), but thedamage was limited to the extent that it did not affect the outside world and the impact on thedecommissioning process has been reduced. As for the ALPS-treated water, the government hasannounced a policy of discharging it into the ocean, on the premise that safety will be ensured andthat measures against reputational damages will be thoroughly taken.
On the other hand, due to the spread of the new coronavirus infection, the fuel debris retrieval
from Unit 2, which was scheduled to start within 2021, is expected to be delayed by about one year,
and efforts are currently being made to minimize this delay. The Tokyo Electric Power Company,
Incorporated (hereinafter referred to as “TEPCO”) has updated its Mid-and-Long-term
Decommissioning Action Plan, which was announced in 2020, in March 2021 to specify the outlook
for decommissioning work based on the above.
The "Technical Strategic Plan 2021 for Decommissioning of TEPCO's Fukushima Daiichi Nuclear
Power Station" (hereinafter referred to as the "Technical Strategic Plan 2021") characteristicallydescribes the issues to be addressed for the trial retrieval of fuel debris to minimize the impact of
the new coronavirus, the issues to be discussed for the selection of a method for further expansionof retrieval scale, and the efforts for the ALPS-treated water, while offering the prospects ofprocessing/disposal method and technology related to its safety (hereinafter referred to as
the ”Technical Prospects”), that was to be presented around FY2021 in the " Mid-and-Long-term
Roadmap for Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station" (hereinafterreferred to as the "Mid-and-Long-term Roadmap").

Structures and systems toward the decommissioning of the Fukushima
Daiichi Nuclear Power Station
Looking ahead to the medium-to-long-term decommissioning work, TEPCO has been working
to build and strengthen the project management structure to address each issue in a systematicmanner and steadily proceed with the decommissioning work. In April 2020, the organization was
reorganized, and the general framework of its management structure and scheme was established.
After this, it is important to enhance and upgrade the management methods and make themeffective and rooted in the field operations. From the financial perspective, the Nuclear Damage
Compensation and Decommissioning Facilitation Corporation (hereinafter referred to as “NDF”)

2

has been carrying out the management of a reserve fund for decommissioning since October 2017
to ensure immediate decommissioning work. The management task aims are, in every fiscal year,(1) TEPCO will deposit the amount at NDF that is specified by NDF to implement decommissioning
appropriately and steadily, as well as that approved by the Minister of Economy, Trade and Industry,and (2) based on the “Withdrawal Plan for Reserve Fund for Decommissioning” (hereinafterreferred to as “Withdrawal Plan”), that was jointly prepared by NDF and TEPCO and approved by
the Minister of METI, TEPCO will withdraw the reserve fund and implement decommissioning. At
present, three years have passed since the decommissioning reserve management was introduced,
and it is contributing to the proper and steady implementation of decommissioning. (Fig.1）

Nuclear Emergency Response Headquarters (Director: Prime Minister)Council for the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station*1(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

Mid-to-Long-Term risk map

Apply forapproval➢ Development of a mid-to-long-term strategy

Withdrawal plan

plan

R&D organization

International Research Institute for
Nuclear Decommissioning (IRID)*2
Share progress
Japan Atomic Energy Agency (JAEA), and challengesetc.
➢ R&D implementation
Report➢ Strengthen international partnershipReserve Fund for➢ Management of Reserve Fund for
Decommissioning
Decommissioning
Advice, guidance, recommendations,supervision and support
Reserverelated to project management, etc.

Disburse-ment

Apply for report

Technical ➢ Tech. support for progress management of important
issues (in collaboration)
Strategic ➢ R&D planning and progress management

Monitoring, examination

Approve

Nuclear Damage Compensation and Decommissioning Facilitation Corporation

Granting of
project budget

Progressmanagement

Nuclear Regulation Authority➢ Approval of implementation
plan, pre-service inspection,
welding inspection, etc.
➢ Providing goals fordecommissioning

Minister of Economy, Trade and Industry
Presentation ofimportant issues

ReportReport on theoutcomeReportBidirectional dialogue

Local residents and communities

Organizations related to decommissioning➢ Decide the direction of decommissioning and contaminated water
treatment

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, entire sitemanagement, etc.
Mid-and-Long-term➢ Through TEPCO's management reform, the funds required for decommissioning should be reserved
Decommissioning Action Plan
responsibly (Implementation of the 4th special business plan)➢ Detailed measures for facility safety and protection of nuclear fuel material (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
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

Technical 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• 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

3

3

The Technical Strategic Plan
NDF has been compiling the Technical Strategic Plan every year since 2015 for the purpose ofproviding a solid technical basis for the Mid-and-Long-term Roadmap, contributing to its smoothand steady implementation, consideration of revisions, achievement of the goals of the Nuclear
Regulation Authority's "Target Map for Reducing Medium-Term Risk at TEPCO's Fukushima Daiichi
NPS," and providing a basis for the Policy for Preparation of Withdrawal Plan. The TechnicalStrategic Plan also makes suggestions that will contribute to the annual revision of the Mid-andLong-term Decommissioning Action Plan from a technical perspective.
The Technical Strategic Plan 2021 presents a technical strategy from a medium-to-long-term
perspective that overlooks the overall efforts at the Fukushima Daiichi NPS in order for project
operators to steadily implement decommissioning work toward the goals of the Mid-and-Long-term
Roadmap that was revised in 2019. In particular, fuel debris retrieval, which is a highly difficult task,
is approaching, and the roles of the government, NDF, TEPCO, research institutes, etc. arebecoming more significant to realize this task.

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2 Concept for reducing risks and ensuring safety in thedecommissioning of the Fukushima Daiichi NPS
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.

Concept of reducing risks caused by radioactive materialsi.

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.
ii.

Identification and assessment of risk sources
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.
It is also important to identify risks that have not been anticipated before. Although it is not easy
to identify such risks, when an unexpected event occurs, analyzing the event to clarify causes that
had not been 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. Before this event, it was assumed that solid content such as rubble would not
immediately transfer radioactive materials to the environment due to container damage. 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. For the PCVs for which the current
state is not well-understood, understanding the damage condition by internal investigation andassessment of the situation at the accident, and estimation of aging by monitoring/evaluation areuseful for risk identification. Regarding external events such as natural disasters, it is necessary tothoroughly evaluate in advance the consequences of and the necessity of countermeasuresagainst 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

5this purpose, TEPCO needs to make efforts to learn from the unexpected events as describedabove.
Table 1 Major risk sources at the Fukushima Daiichi NPS
Fuel debris
Spent fuel

Fuel in SFPs

Contaminatedwater, etc.

Fuel in the Common
Spent Fuel Storage Pool
Fuel in dry casks
Stagnant water inbuildings

Zeolite sandbags

Secondarywaste
generated bywater
treatment

Stored water in weldedtanks
Residual water inflanged tanks
Waste sorption vessels,etc.

ALPS slurry

Sludge generated at thedecontamination device
Concentrated waste
liquid, etc.

Rubble, etc.

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

Contaminated structures, etc., in thebuildings

Fuel debris in RPVs/PCVs in Units 1 to 3
Fuel assemblies stored in the spent fuel pools (SFPs) in Units 1 and
2Fuel assemblies stored in the Common Spent Fuel Storage Pool
Fuel assemblies stored in dry casks
Contaminated water accumulated in the reactor buildings of Units
1 to 3, process main building and high-temperature incinerator
building, and sludge containing α-nuclides at the bottom of buildingsof Units 1 to 3
Sandbags containing zeolite placed on the basement floors of theprocess main building and high-temperature incinerator building
Strontium-treated water and ALPS-treated water, etc. (ALPStreated water and water under treatment) stored in welded tanks
Concentrated saltwater and sludge containing α-nuclides left at thebottom of flanged tanks
Spent sorbents used in a cesium sorption apparatus, a second
cesium sorption apparatus, a third cesium sorption apparatus,
advanced multi-nuclide removal equipment, mobile-type strontium
removal equipment, a second mobile-type strontium removal
equipment and mobile-type treatment equipment, etc.
Slurry produced during treatment by the multi-nuclide removal
equipment and added multi-nuclide removal equipment, and stored
in high integrity containers (HIC)
Flocculated sludge generated during the operation of thedecontamination system
Concentrated waste liquid generated by evaporative concentrationof concentrated salt water with further volume reduction by
concentration, and carbonate slurry collected from the concentrated
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 temporarystorage 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 and PCVs/RPVs that are contaminated with radioactive
materials dispersed due to the accident; and activated materials
generated from operation before the accident

6Color-code for therisk sources basedon the Mid-andLong-term Roadmap** 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 since last year, and the dotted lines or thestarting points of the arrows indicate the locations in the previous year.

Fig. 3 Example of risk levels assigned to the major risk sources at the Fukushima Daiichi NPS

ⅲ．Risk reduction strategy
Interim targets of the risk reduction strategy
Measures for risk reduction include the reduction of the “Hazard Potential” and the reduction of
the “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 the Technical Strategic Plan 2020 towards this goal, Fig.
3 shows the completion of transfer of the fuel from Unit 3 SFP to the Common Spent Fuel Storage
Pool in February 2021; the completion of treatment of the remaining water (ALPS-treated water,etc.) at the bottom of the flanged tank in July 2020 (transfer to welded tanks); and the decrease of
the stagnant water in buildings (transfer to sorption vessels, etc.). In addition, Table 1 specifies thatthe shield plugs and the piping of the standby gas treatment system, whose state have been verified
through field investigations by the NRA, are included in the contaminated structures, etc., in thebuildings.

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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.
Progress of risk reduction
Fig. 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. The number of spent fuel assemblies as an indicator to make the work progresseasier to see in Fig. 4(b), and for Cs-137, the estimated radioactivity (Bq) common to various risk
sources as an indicator in Fig. 4(c), both indicate the progress of the decommissioning work byrepresenting the status of transition to the “Sufficiently stable management” region in a pie chartformat.

(a) Risk reduction process

8(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 2021)(Attenuation in Fig. 4(c) takes into account radioactive decay of Cs-137 from the time of the accident to
the end of March 2021)

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 Primary Containment Vessels (hereinafter referred
to as “PCVs”) of Units 1 to 3 has been estimated to some extent through simulation of the accident
development process, estimation of the places with fuel debris by muon-based fuel debris detection
technology, placement of investigation equipment into the PCVs, radiation dose measurement andvideo photographing in the buildings, and other means. However, there are still significant
uncertainties. Eliminating these uncertainties requires many resources and, in particular, aconsiderable amount of time. In order to realize prompt reduction of risk, 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 with experiment and analysisbased 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 the9operations, thoroughly conducting radiological impact evaluations, and taking appropriate
radioprotective measures. (“Safe”)
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 of this judgment will be widely accepted bysociety.

Approach to ensuring safety during decommissioningi.

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

10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.

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 first 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.
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 the next section.

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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,
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).
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, theFukushima Daiichi NPS is a facility that has suffered from an accident, and unlike a normal reactor
its decommissioning requires an unprecedented approach that can be carried out in a peculiar
environment, such as one with high radiation levels. Therefore, when determining the feasibility ofsafety measures on site, the peculiarities of the on-site conditions, such as high radiation levels
and the environment, shall be considered.
It is also important for ensuring safety tocomplement the design by operations including

operating controls, and to utilize information in design obtained through monitoring, analysis, etc.
ii.

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 current environment with an already high radiation level, further
deterioration of containment barriers, and the possibility of future major natural events (such as
earthquakes or tsunamis), 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 isdivided into several stages, “operation at first stage” is implemented for which practical safety canbe 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

12

operational actions and flexible on-site responses at each stage of the process. The information
obtained at each stage of operation 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.
Hereafter, it is recommended to make it clear as a policy that the information to be gained
through on-site operation should be fully incorporated and accumulated as knowledge inconsecutive activities for ensuring safety. For example, the same applies to risk identification
associated with hydrogen at the time of fuel debris retrieval. Testing to reduce nitrogen supply foran experimental purpose may help identify hydrogen risk, and determine requirements on thenecessary amount of nitrogen supply and reliability of the exhaust systems to ensure safety. 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.

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3 Technological strategies toward decommissioning of the
Fukushima Daiichi NPS
Fuel debris retrieval
i.

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 has been delayed
due to the COVID-19 pandemic. In order to limit the delay to about one year, preparations will
be made for starting retrieval. Continue a series of work including the gradual expansion offuel debris retrieval to acquire knowledge and experience necessary for the further expansionof the retrieval scale.
(3) With regard to further expansion of fuel debris retrieval, consideration will be given to themethods including those for containing, transferring, and storing of fuel debris, by assessing
fuel debris retrieval at the first implementing unit, internal investigations, research anddevelopment, and the on-site environmental improvement, etc.
(Progress)①

Unit 1
In preparation for the start of the PCV internal investigations, which is planned within FY2021,

removal of obstacles within the PCV is being promoted while taking measures to control dust
dispersion and monitoring dust concentration by considering the change in dust concentration
when opening the inner door at the penetration X-2. Also, at the beginning of 2021, during the
preparation of the obstacle investigation in PCV, for the pressure decreasing that were expected tohave occurred due to the addition of external force to the outer door of the penetration X-2, removalof obstacles within the PCV is being promoted while performing measures to suppress theoccurrence.
②

Unit 2The 2019 Med-and-Long-term Roadmap specified Unit 2 as the first implementing unit for fueldebris retrieval, and its trial retrieval was supposed to launch within 2021. However, the process
has been delayed due to the impact of the new coronavirus infection. In order to limit the delay toabout one year, preparations are being made for starting fuel debris retrieval. The arm-type accessequipment (robot arm) has arrived in Japan and started testing.
A plan for gradual expansion of fuel debris retrieval is also underway, the requirements related
to the arm performance of the arm-type access equipment and the interface between the equipment
and enclosures have been clarified and examined (Fig. 5, Fig. 6).

14

③

Unit 3
As for Unit 3, the result of sampling the suppression chamber (hereinafter referred to as “S/C”)

water (conducted in 2020) using the piping connected to the S/C shows that the concentration ofradioactive materials such as Cs-137 is higher than that of the stagnant water in buildings.
Therefore, its impact on the treatment of contaminated water is being considered, and the analysis
results are being incorporated into the PCV water intake system. In addition, the conceptual study
on further expansion of fuel debris retrieval is in progress.
④

Impact of and response to the earthquake on February 13, 2021, with its epicenter off the coastof Fukushima Prefecture
Due to the earthquake that occurred off the coast of Fukushima Prefecture on February 13,

2021, lowering of the PCV water level was observed in Units 1 and 3. Water injection into thereactor is continuing, from the enhanced monitoring of plant parameters for Units 1 to 3, as there
are no significant changes in plant parameters, the cooling condition of fuel debris is considered to
be intact. It is assumed that this drop in water level may have been caused by an increase inleakage from inside the PCV due to changes in the condition of the damaged areas previously
identified in the PCV and its newly damaged areas. Going forward, the change in parameters suchas water level will be checked by water injection shutdown testing, and expansion of knowledge be
considered.
In light of the recent earthquake, it is necessary to enhance monitoring systems to observechanges in plant conditions, perform impact assessment to maintain/manage systems andbuildings over the med-and-long-term, and promote technical development required to understandthe situation.

(TEPCO material edited by NDF)

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

15

（TEPCO material edited by NDF)

Fig 6 Image from retrieval to temporary storage of fuel debris(Gradual expansion of retrieval scale)ii.

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.
In Unit 2, trial retrieval and PCV internal investigation will be performed, and implement thegradual expansion of fuel debris retrieval based on the findings. In addition, a conceptual study on
the further expansion of fuel debris retrieval for Unit 3 is planned.
Trial retrieval and PCV internal investigation, and gradual expansion of fuel debris
retrieval① Development status and prospects of trial retrieval/internal investigation equipment
For the trial retrieval and PCV internal investigation 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 thearm-type access investigation equipment is moved in/out of to retrieve fuel debris inside the PCV.
In this operation, an expansion will be made to provide an isolation chamber to be built duringopening the penetration X-6, and an enclosure to be newly provided, since the conventional
containment barrier was located in the blank flange part of the penetration X-6. Although small inscale, this is a fundamental 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 approach that enters a new stage.
Although it is important to make efforts to minimize delays caused by the new coronavirus
infection, mockup testing that takes full account of uncertainties on site is also important in termsof actual site applicability and ensuring safety. In addition to simulating the severe environment onsite, this mockup testing should clarify the parts that cannot be simulated and make enoughpreparations for practical application. The NDF will also confirm the test plan and whether
measures are sufficient.
The key technical issues, countermeasures, and points to consider are described below.

16

・ Dust dispersion prevention associated with removal of deposits in the penetration X-6.
For the removal of deposits in the penetration X-6 and AWJ cutting of obstacles, it is essential
to develop a detailed work plan in accordance with the preliminary implementation and use it in thelater stages and ensure safety accordingly (for example, break down work steps; proceed to thenext step after confirming there is no problem with the dust dispersion monitoring results in eachstep; and take countermeasures and proceed to the next step if any sign of abnormality isobserved).
NDF will confirm whether a sufficient level of safety is secured for performing work, including
whether the work plan is well-developed by TEPCO, the plan is fully implemented without fail, andwork is stopped when necessary.
・ Considerations for the risk of spreading the new coronavirus infection
The performance confirmation test and mockup test simulating the on-site environment in the
UK have been canceled, and it is planned to perform testing by bringing the equipment into Japan.
For the performance confirmation test in Japan, it is essential to secure the UK engineers, and it isnecessary to maintain the backup system on the UK side in the event of a defect, while, sharing
information and communicating smoothly with the UK engineers.
It is also important to make all possible preparations for the risk of the new coronavirus infection
expanding in Japan. The 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. The
NDF also participates in meetings with contractors and their subcontractors to closely check thestatus and support risk assessment.
・ Limitations in the scope of trial retrieval and internal investigation, and incorporation 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 arm can access the bottom of the pedestal is limited. Thus, the possible range ofneutron measurement and trial retrieval from the bottom of the pedestal is limited. Assuming that
fuel debris at the bottom of the pedestal cannot be retrieved, it is also planned to retrieve thedeposits on the platform which are highly likely to be fuel debris, as same as those at the bottomof the pedestal. Given the limited scope of investigation and trial retrieval, greater consideration isrequired 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.

17

・ Human resource development and technology transfer for the next step (gradual expansionof 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 thoseinvited from outside as needed, to develop human resources to foster field-oriented
perspectives/feelings, and to transfer techniques cultivated through these activities.
② Development status of gradual expansion of retrieval scale and prospects
The retrieval equipment to be used for gradual expansion of the retrieval scale will be improvedby increasing the weight capacity and enhancing accessibility while complying with specificationsof the devices for trial retrieval and PCV internal investigation.
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 enclosures for fuel debris
In the retrieval operation, the process is repeated from carrying fuel debris retrieved from thePCV into the enclosure, storing in unit cans and to carrying out to the outside of the enclosure foron-site transportation. As a result, the enclosure gradually becomes contaminated, and it isimportant to secure the containment performance of the enclosure.
This work is performed by controlling the pressure in the enclosure as the arm-type accessequipment is moved in/out. Therefore, in order to confirm airtightness performance and operation
reliability, through the duration, it is important to perform prior mockup testing, post-installation
testing of the equipment, and subsequent abnormality monitoring.
・ Ensuring reliability of a dual arm manipulator
The dual arm 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, a dual arm manipulator that performs various operations may berepaired or replaced during the in-service period. Thus, the device to carry out the manipulator tothe maintenance building is under development.

18

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
TEPCO. It is also important to leverage the experience gained through the in-service maintenanceof equipment/devices for further expansion of the retrieval scale. Therefore, a system that canreliably preserve maintenance records, including failure histories and their measures, should beestablished.
③ Further expansion of fuel debris retrieval
Toward further expansion of the retrieval scale, methods should be selected based on the
viewpoint that “fuel debris retrieval is an important process in decommissioning, and its retrieval ina reliable manner affects the success/failure of the decommissioning project”, and from acomprehensive standpoint (in anticipation of technical feasibility as well as business continuity). In
addition, TEPCO should take responsibility for selecting the method. Therefore, this section
describes in detail how to select 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 requirements(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 has been engaged in the conceptual study for further expansion of the retrieval scale.
As part of this conceptual study, TEPCO will consider scenarios for fuel debris retrieval and, at theend of FY 2021, identify promising methods (top/sub candidates). Subsequently, based on theinformation obtained from the survey results, TEPCO will finally narrow down the possible methods(top/sub candidates), and decide the method with its design in mind.
The following are the points to be considered for examining retrieval scenarios and methods.
・ How to select retrieval methods
In selecting the method, based on the Five guiding principles (Safe, Proven, Efficient, Timely
and Field-oriented), a determination should be made not only to satisfy the target of safety levelbut also to use the attributes (evaluation items) such as cost and schedule as indexes for selection.
It is necessary to quantify these evaluation items as much as possible by using a multi-attribute
utility analysis method, etc. It is believed that the most important factors in the process of selecting
methods are the evaluation items used as indexes for determination and how to weight theseindexes. In setting these indexes, a decision should be made not only based on the approach of
TEPCO as an operator, but also from a comprehensive viewpoint developed through discussions
with experts. Normally, the selection of methods should be based on the results of internal
investigation. However, in a situation with many uncertainties like at the Fukushima Daiichi NPS, it
is considered necessary to proceed with examination based on the currently available informationand then to feed back the results gained from the investigation. As for the results of method
selection, it is also important to make efforts to disseminate information in a careful manner so thatthe evaluation results will be widely accepted by society.

19

・ Development of retrieval scenarios
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.
In considering fuel debris retrieval scenarios, different cases are assumed, where fuel debris will
be retrieved by the side-access or top-access methods, or combining both. Then, examinations
including internal investigation required for each case will be made to consider several paths. This
study intends to assume in advance different results obtained from PCV/RPV internal investigations
or technical studies in the future, and then conduct 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.
It is also important to formulate a specific schedule with considering these fuel debris retrieval
scenarios.
・ Clarification of requirements
With regard to further expansion of the retrieval scale, the methods will be considered, including
those for containment, transfer, and storage of fuel debris, based on the findings from fuel debris
retrieval in Unit 2 (trial retrieval, gradual expansion of the retrieval scale), 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 otherwork. In addition, because of the high radiation dose on site and the limited understanding of thesituation inside the PCVs, the scope of work will be extensive. Therefore, it is important to specify
the requirements (containment, criticality, operability, maintainability, throughput, etc.) required for
operations and devices more clearly and proceed with the work. Attention should also be paid to
the interaction between the requirements.
・ Process for narrowing down promising retrieval methods
Based on the development results of the Project of Decommissioning and Contaminated Water
Management, the latest findings at home and abroad are taken into consideration to derive ideas.
Then, primary/secondary screening will be performed to gradually narrow down the methods. The
primary screening verifies compliance with requirements and constraints, while the secondary
screening quantifies and weighs each evaluation item. A multi-attribute utility analysis method, etc.,
is utilized for such screening process. Diverse ideas are expected to be derived, but it is important
to conduct objective evaluation based on this process and to narrow down the methods.
Based on the above considerations, NDF will evaluate the validity of the results of TEPCO'sconceptual studies (Fig. 7).

20

Fig. 7 Flow of retrieval method study (conceptual diagram)

Issues in each technical field for further expansion of the retrieval scale are described in (3).
Continuation of accident analysis activities (clarification of events that occurred at theaccident 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 todetermining the cause of the accident and decommissioning, and indirectly to the enhancement of
nuclear safety.
TEPCO and 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, and the operation status of
emergency cooling and depressurization equipment, by comparing the results of sample analyses
with mock-up testing on accident progression and past scientific knowledge. Moreover, TEPCO’s
ongoing 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 responsible for continuing accident
investigations/analyses established “The Study Committee on Accident Analysis of the Fukushima
Daiichi Nuclear Power Station”, and is also investigating the operating floor in Unit 2, the inside of
the reactor building in Unit 3, and SGTS filter lines, etc., with cooperation from TEPCO, andcompiling an interim report. Based on these investigations, the Nuclear Regulation Authority has
assessed that a large amount of Cs exists between the first and second layers of the shield pluginstalled on the operating floor in Units 2 and 3. Since the information related to the accident
analysis may be affected by the dismantling of facilities due to the progress of decommissioning
work, a liaison/coordination meeting for decommissioning and accident investigation has been
established, and has communicated and coordinated among NRA, the Natural Resources and21

Energy Agency, TEPCO and NDF regarding accident analysis and decommissioning. 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 a gamma cameras, and to collect piping samples for analysis after cutting. As
countermeasures against radiation of radioactive dust during cutting, urethane foam injection andlocal exhaust ventilation are being considered, and care is being taken to ensure that
decommissioning work and accident investigations do not affect the surrounding residents or theenvironment.
TEPCO is also planning to systematically conduct on-site investigation while estimating the stateof the reactor core and PCV, and unsolved issues. After a lapse of 10 years since the accident, theradiation dose has decreased due to the decay of fission products (hereinafter referred to as "FP”)
and environmental improvements on site, and accessibility to the reactor 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 to collaborate with each organization,and continue these activities to a reasonable extent to clarify the events that occurred at theaccident, 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, , PCV internal investigation andgradual expansion of the retrieval scale from the first floor of the reactor building are not directly
affected by the trial retrieval. In order to further expand the retrieval scale, however, it is importantto fully recognize high radiation doses in the shield plugs, taking into account the possibility thataccess from the operating floor (top-access) is required, and examination of retrieval methods withdecontamination, shielding, and containment in mind.
Technical issues for technical requirements and future plans
The current status and issues of the following items are described below.
a.

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.
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.

22

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.
In the subsequent work such as fuel debris cutting, it is necessary to construct the containment
function of the gas phase system in consideration of re-scattering of Cs, etc., that adhere to theequipment and structures in the PCV, aerosolization of water containing radioactive materials, andgeneration 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.
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 and Contaminated Water
Management. In the future, the effect on the surroundings will be assessed based on the monitoring
results of the changes in condition such as the dispersion of α-dust associated with the work, andthe retrieval scale of fuel debris will be gradually expanded. In doing so, identification of necessaryfunctions as secondary containment functions and their establishment are also being considered,
while assuming the possibility of an increasing impact on the surroundings.
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 bygripping 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 to the environment, it may be of great importanceto establish a cooling water circulation/purification system, and a liquid phase containment function
in consideration of prevention of 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, theProject of Decommissioning and Contaminated Water Management has been promoting researchand development. In parallel with this, the establishment of a PCV circulating cooling system thattakes water from the PCV and injects it into the reactor for cooling, which is beneficial in terms of
preventing the spread of cooling water containing α particles, was considered in research anddevelopment 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 cooling23

water by stage and verify the validity of the containment function to be built in the subsequent stage
based on the results (information on 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 same Project of. The scale of fuel debris retrieval will be expanded gradually,
based on the results of monitoring 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 toprevent the outflow of cooling water to groundwater and to appropriately control the water level in
the PCV. Safety systems are to be established taking this into consideration.
③ Issues in cooling functions
Fuel debris generates decay heat, for example in Unit 2, the maximum heat generation is still
estimated to be 69 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 thiscooling function, the technical issues to be addressed for the time being include setting of the target
temperature inside the PCV to make each task feasible, as well as the countermeasures to betaken under the assumption of cooling function abnormalities when each task is performed. Whileessential countermeasures would be to continue cooling by early recovery of the cooling water
circulation system or by mobile equipment, etc., it is necessary to evaluate changes in the PCVinternal 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, water injection into thereactor was temporarily suspended with the aim of optimizing operation/maintenance managementof cooling systems and emergency response procedures, etc. In light of these results of the water
injection shutdown test, from FY 2020 onward, testing will be planned and performed dependingon the purpose, taking into account the situation of each unit, for the decommissioning in the future.
Based on this policy, water injection shutdown tests are being performed for each unit, and inconsideration of the situation of lowering PCV water level during termination of water injection, it isplanned to study water injection methods for the future such as further reduction of the amount ofwater 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.

24However, it should be considered that the injection of cooling water may become redundant in
the future due to further decrease in the amount of decay heat along with reduction in the amountof fuel debris.
④ Issues in criticality control
The possibility of re-criticality of the fuel debris at the Fukushima Daiichi NPS is assumed to be
low based on the expected condition of the existing fuel debris from an engineering perspective.
However, the possibility of changing the shape of fuel debris must be taken into account as thescale of retrieval is expanded. It is essential to ensure reliable criticality management during
retrieval and to establish an appropriate control method for ensuring prompt detection andtemporary shutdown/re-start of operation in case of an unexpected criticality. In order to ensure
criticality control as a consideration of the work plan for fuel debris retrieval, it is necessary toestablish an appropriate control method to ensure prompt detection, suspension and resumptionof work even in the case of an unexpected criticality.
In the initial stage of fuel debris retrieval work, fuel debris should be retrieved by limiting thetreatment amount based on methods that will not significantly change the fuel debris shape. In theprocess of expanding the retrieval scale, by utilizing the site information from the preceding
operations for the subsequent safety evaluation, reliable criticality control should be made thatcombines the monitoring by the operator and the decision-making process to suspend and resume
work while reducing the design uncertainty. As control measures, by combining measures suchas preparation for neutron absorber insertion with continuous monitoring and subcriticality
measurement of neutron flux in the vicinity of the fuel debris,

technology development isunderway to respond to the increase in retrieval volume.
⑤ Issues in the structural integrity of PCVs and buildings
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, the cooling function wasmaintained during the earthquake that struck off the coast of Fukushima Prefecture on February
13, 2021, although lowering of the water level in the PCVs of Units 1 and 3 was confirmed. In lightof this earthquake, in order to maintain and manage the equipment/systems and buildings withthe above functions over the medium-and-long term, it is necessary to conduct impact

25

assessments on the accident impact, aging and external events (earthquakes and tsunamis, etc.)
anticipated during the decommissioning period. In view of the fact that the past assessment ofthese effects was limited, it is necessary to make maximum use of existing techniques andevaluation results for planning and implementing an investigation plan, in which remote control
under a high radiation environment is a challenging issue, and to develop underlying technologies
to understand the situation. In so doing, while giving priority to safety, it is useful to actively
introduce the latest knowledge and achievements not only in the nuclear field but also in otherfields.
As for 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 the structural integrityof equipment/systems and buildings, while considering the state of the site, it steadily proceedswith the examination based on the latest design information.
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
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 and Contaminated Water Management tosupport TEPCO’s engineering.
The main work areas are high radiation dose areas such as inside the reactor buildings. Also,
there comes the need to handle nuclear fuel materials containing α-nuclides from fuel debris witha 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.
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. As
for the reduction of the radiation exposure of workers in the reactor building, after conducting
sufficient investigations on the radiation dose distribution and state of contamination, including thecontribution from the surroundings of the work areas, it is important to identify the source locations
and intensity as much as possible and to build the radiation dose reduction plan with the target
dose rate in consideration of the margin for the radiation exposure dose limit for workers specified
by laws and regulations. In the radiation dose reduction plan, it is important to plan for reducing thetotal radiation exposure dose to as low as reasonably achievable with respect to work hours inaccordance with dose limits and required work hours to accomplish operations. Based on these,
the development of the digitization technology for the environment and radiation source distribution
which introduces visualization technology has been in progress since FY 2021. Moreover, indeveloping remote technologies for environmental improvement and removal of obstacles underhigh radiation dose, the obstacles to be removed have been selected and the elemental

26

technologies have been extracted in accordance with the required functions, and technicalinvestigation is underway since FY 2020.
In the future, it will be necessary to develop management methods and equipment that can
detect leaks and contain αnuclides to prevent diffusion into the air and into the water treatment
system during a series of work processes. For a further expansion of fuel debris retrieval, it isnecessary to develop a database that enables information sharing and rapid feedback to the next
work plan. In addition, adequate radiation exposure control should be conducted after formulated
a long-term work plan that includes not to concentrate workers’ radiation exposure on individual
workers and to help reduce whole workers’ radiation exposure. Support should be provided toestablish a system that manages and operates various information on the entire Fukushima Daiichi
NPS in an integrated, step-by-step manner.
b.

Technical issues related to fuel debris retrieval methods① 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.
For trial retrieval and gradual expansion of fuel debris retrieval, TEPCO is currently proceedingwith specific engineering studies to conduct an access route from penetration X-6 in Unit 2.
On the other hand, toward a further expansion of fuel debris retrieval, studies are underway on
the construction of access routes from the side opening of the PCV to fuel debris, based on the
results of research and development conducted to date by the Project of Decommissioning andContaminated Water Management. In the side-access method, the issue is to address containment,
shielding for connecting structures between newly installed heavy structures and the side-openingof the PCV, and seismic displacement, and technical development of the method is underway using
lightweight cells and fixed rails as well as access tunnel systems. As for the top-access methodfrom operating floor, enhancing throughput is being examined including a method to retrieve andtransport interfering structures as a single or large unit while ensuring containment and shielding.
The NRA pointed out the possibility that a large amount of Cs might exist on the undersurface ofthe shield plugs of Units 2 and 3 from their evaluation of TEPCO's radiation dose measurementson the operating floor. Therefore, the top-access method requires consideration of constructing
access routes with this in mind.
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 and it is important toproceed with research and development toward a planned scale expansion.

27

② Issues in development of devices and equipment
Devices and equipment for fuel debris retrieval need to be developed with emphasis on safety,
reliability, and efficiency. To flexibly respond to the situation, these devices/equipment should beconsidered radiation resistance, maintainability, remote operability, high reliability, 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 andContaminated Water Management. After the gradual expansion of fuel debris retrieval, TEPCO
needs to take over and substantiate the development results. TEPCO is proceeding with theengineering of the robot arms, etc., to be applied to Unit 2, while preparing education/training forthe fuel debris retrieval operations using these remote devices.
As for devices and equipment for further expansion of fuel debris retrieval, development isunderway for retrieval methods for improving efficiency, retrieval/handling systems according todiverse conditions of fuel debris, and dust collection systems, etc. for dust generated during fueldebris fabrication. TEPCO is currently conducting a concept study for selecting a method for further
expanding the scale of retrieval, and plans to narrow down the number of methods for thesubsequent design study by the end of FY 2021. Further development of devices and equipment
should be planned and promoted in light of the selected method.
As for how to proceed with development, it is necessary to continue development for newly
emerging important issues based on the information obtained from preceding investigations andretrieval work. The developed devices and equipment need to verify the results through repeatedmockup tests to demonstrate that they can realize their performance safely and reliably at the actualsite. The mockup tests need to be implemented in a facility simulating the severe on-siteenvironment containing significant uncertainties. Therefore, NDF and TEPCO have been engaged
in examining how to proceed with the remote mockup test plan. From 2021, it is expected thatTEPCO will take the initiative in promoting examination and materialization.
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

28

issue, which is essential for fuel debris retrieval. TEPCO has been examining the building of safetysystems incorporating the above through their engineering work.
The working area required for installing fuel debris retrieval equipment/related devices andsystem is now being investigated. In considering the handling of high radiation dose areas in thereactor buildings and interference with other tasks, installing systems outside of the existingbuildings is also being considered.
c.

Technical issues related to safe and stable storage of fuel debris① Issues in handling fuel debris (containing, transferring, and storing)
Before initiating fuel debris retrieval work, a comprehensive system should be established thatconsists 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 thefollowing is being progressed until the end of FY 2020:
・ Development of basic specifications for the container, (structure, size and quality ofmaterials) and demonstration of its structural integrity by testing.
・ Examination of a practical prediction method of hydrogen gas generation from fuel debris;
determination of a vent mechanism on the container by using the said results; andestablishment of safe transferring conditions.
・ Development of drying technology applicable to fuel debris and consideration on a drying
system using this technology.
Moreover, in reference to the results of these studies, TEPCO continues their activities tomaterialize systems and devices/installations used for the process from containing to storing fueldebris, which are required for gradually expanding the scale of retrieval, in coordination with otherassociated projects. In addition, specific transferring routes, storing technologies/forms and its
locations in light of the usage plan for the entire site are taking shape. At present, since theinformation and knowledge on the properties of fuel debris is extremely limited, the systems anddevices/installations will be designed based on conservative assumptions of conditions such as theproperties of fuel debris. Therefore, in the design of equipment and facilities for containing,transferring and storing of fuel debris for further expansion of retrieval scale, it is important toproceed in a streamlined manner by utilizing various measurement data such as the amount ofhydrogen generation and fuel debris properties that have been collected and accumulated in thetrial retrieval and gradual expansion of retrieval scale, as well as knowledge and experience on thehandling of fuel debris during the operations from receiving of the onsite transport container to thetemporary storage.
It is also necessary to address safeguards requirements when specifying the equipment andsystems from containment to storage of fuel debris.
The Mid-and-Long-term Roadmap stipulates that the processing/disposal methods of theretrieved fuel debris shall be investigated and fixed during the third phase after starting the fueldebris retrieval work.

29

② Issues in sorting out fuel debris and radioactive waste during fuel debris retrieval
In the fuel debris retrieval work, structures to which molten fuel are partially adhered will also be
removed 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 core fuel with concreteat the PCV bottom. Of these, if substances on which a small amount of molten fuel is adhered are
all deemed as fuel debris, the amount would be enormous. It may become an obstructive factor inadvancing decommissioning because scales of facilities and sites for fuel debris storage becomelarger. This requires the development of sorting techniques for fuel debris and radioactive waste,i.e., sorting scenarios (sorting is performed in which process from retrieval to storage), sorting
criteria and necessary measurement technique/devices.
It is determined that those requiring special attention and facilities/systems for handling andstoring to maintain subcriticality can be considered as fuel debris. Accordingly, it is recommended
to aim for sorting out fuel debris based on the measurement results of the amount and its
concentration of nuclear materials. As a first step in response to this, studies were conducted toconsider which operation processes is feasible for sorting through to storage (sorting scenarios),
and to Investigate which technologies may be capable of measuring the amount or content of
nuclear fuel materials. Based on these studies, it is currently considered as incredibly difficult
challenge to measure or estimate the amount and concentration of nuclear materials in the
retrieved materials from the PCV, which required innovative technology development.
In developing measurement techniques and devices, it is important to understand themeasurement errors first. Major factors affecting measurement errors include the fuel debris
properties and the condition and location of nuclear fuel material in fuel debris storage condition inunit cans and containers, and there are many factors other than errors depending on themeasurement device itself. The extent of such impact is highly uncertain at present due to a lackof knowledge on the properties of fuel debris. Therefore, in parallel with the development of
measurement technology and actual measurement device by iterating actual measurement using
mockup fuel debris, etc., it is considered beneficial for R&D in terms of cost and time saving to
identify factors influencing measurement errors and its strength accumulated by a number ofnumerical experiments by computer and incorporate findings such as the extent of influence into
the development of 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. Such research and development
activities are just getting started since FY 2020 as the Project of Decommissioning andContaminated Water Management, and this R&D is greatly desired to be accelerated in the future.
Knowledge on the properties and actual storage conditions of actual fuel debris is anticipated tobe accumulated through trial retrieval and gradually expanded-scale of furl debris retrieval. By
comparing the results of numerical experiments using the improved analytical model and expanded
analysis condition based on these accumulated knowledge with the results of actual measurements
using mock fuel debris manufactured based on the knowledge on the properties of actual fuel debris,

30

it is possible to improve the accuracy of measurement technologies/devices and to further
accelerate its development.
It is desirable that development of measurement techniques/devices required for sorting fueldebris and radioactive waste is to be continued in this manner. It is also important to continue
activities to enhance the effectiveness and practical applicability of sorting methods (sorting criteria,
scenarios, measuring techniques/devices) by leveraging knowledge and information on the fueldebris properties obtained by planned PCV internal investigation and analysis results of fuel debris
samples taken during trial retrieval, and gradual expansion of fuel debris retrieval and so on.
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.
8.

31

Short term (approx. 3 years)
24
2021

Fiscal Year

2022

2023

25

Mid-to-Long-term (FY2024 to End of FY2032)
26
27
28
29
30
31
2032(year)
2026▽Start of the fuel debris retrieval in theinitial unit (by the end of 2021)* Due to the impact of coronavirus infection,
the start will be delayed in about 1 year.

RM milestones
Improve environment
inside the building

Trial retrieval(Unit 2)

: Work period: The period during whichcha nge is expected
Technical studies on indivi dual items relating to on-site construction

Trial retrieval andinternal investigations

Manufacture and install
the retrieval device

On-s ite
opera tion

: To be conducted a s required

R&D

Technical issues in the Government-led R&D program on
Decommissioning a nd Contaminated Wa ter Management

Characterize the fueldebris
Improve environment
inside the building

Gradual expansionof fuel debris retrieval(Unit 2)

Gradual expansion of fuel debris
retrieval

Fuel debris retrieval facility/safety system/fuel debris
temporary storage facility/maintenance facility

Design and production

Installation

Characterize the fuel debris

Review of the program on Decommissioning
廃炉・汚染水対策事業、東電自主事業
and Contaminated Water Management andにおける検討TEPCO's voluntary project- Development of technology for detailed-PCV内部詳細調査技術の開発
investigation inside PCV- Development of technology for the-燃料デブリの段階的に規模を拡大した
gradualexpansion of fuel debris retrieval
取り出し技術の開発

Technical study by TEPCO- Technological 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 safety system (Gaseous system, water treatment system, criticarity management system)(4) Providing temporary storage facility of fuel debris
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 exhaust towers of Units 1 and 2/removal of transformers, etc.)

Further expansionof fuel debris retrieval(Units 1/3)

Improvement of the environment inside and outside the Unit 3 building(Inside the building: PCV water lowering/dose reduction;
Outside the building: removal of the exhaust towers of Units 3/4, removal of transformers, etc.)

Fuel debris retrieval facility/safety system/fuel debris storage facility/maintenance facility/training facility and others

Review on the concept,

Actual site applicability verification
development (Remote installation,
dust diffusion control, etc.)

DesignProduction, installation, and retrieval

Review of the program on Decommissioning

廃炉・汚染水対策事業、東電自主事業
and Contaminated Water Management andにおける検討TEPCO's voluntary project- -原子炉建屋内・外の環境改善のためのDevelopment of technologies forenvironmental improvement of inside and
技術開発
outsidereactor building- -１号機PCV内部詳細調査技術の開発
Development of technology for detailed
investigation inside Unit 1 PCV- Development of investigation technology-原子炉圧力容器内部調査技術の開発
inside RPV- -燃料デブリ性状把握のための分析技術
Development of analytical and estimation
techniques for characterization of fuelの開発
debris- -燃料デブリ・炉内構造物の取り出し規模
Development of technologies for retrieving
fuel
debris and internal structures towardの更なる拡大に向けた技術の開発
further expansion of fuel debris retrieval- -遠隔装置保守技術の開発
Development of technologies formaintaining remote equipment- Development of technologies for containing,-燃料デブリ収納・移送・保管技術の開発
transferring and storing fuel debris- Development of support technology for-１Ｆ廃止措置統合管理のための支援技
integrated management of 1F術の開発
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* It is assumed that Unit 3 will be examined in advance and expanded to Unit 1.

Fig. 8 Technical issues and future plans on fuel debris retrieval (progress schedule)

32

Waste managementi.

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) Countermeasures integrated from characterization to processing/disposal of solid waste arestudied from the expert point of view, and the prospects of processing/disposal methods andtechnology related to its safety should be made clear by around FY 2021.

<Key points of "Basic Policies on Solid Waste”>(1) Thorough containment and isolation
Thoroughly containment and isolation radioactive materials to prevent human access to them,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 to proceedwith studies on processing/disposal methods of solid waste.
(4) Thorough storage
Generated solid waste should be stored safely and reasonably according to its characteristics.
Storage capacity should be secured to ensure that the waste can be stored within the site of
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 requirements ofdisposal are established.
(6) Promotion of effective R&D with an overview of overall solid waste management
To confirm required R&D tasks after cooperating with each R&D field in characterization andprocessing/disposal and overviewing the overall management of solid waste.
(7) Development of continuous operational framework
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 basedon 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, treatment to disposal.
Since a large amount of solid waste with various characteristics is generated in association withdecommissioning of the Fukushima Daiichi NPS, the efforts are being made in accordance with theabove "Basic Policies on Solid Waste” summarized in the Mid-and-Long-term Roadmap. TEPCO

33

is required to ensure safe and reasonable storage of the solid waste generated. For advancetechnical examination of integrated measures for solid waste, from characterization toprocessing/disposal, NDF and the organizations concerned are working on initiatives based on
their respective roles. In addition to improvements in characterization analysis abilities, thedevelopment is underway for the establishment of a flexible and reasonable waste stream (the flowof the integrated measures from characterization to processing/disposal), with the goal of providing
the Technical Prospects by around FY2021.
Current status of Storage 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. From theperspective of reducing the amount of solid waste, as for the concrete rubble that surface dose rateis equivalent to the site background radiation dose is recycled as roadbed material. For metal andconcrete rubble, and scrapped flanged tanks with extremely low surface radiation dose rates,
reuse/recycling are under consideration while temporary storage outside solid waste storage iscontinued for the time being.
Prospects of processing/disposal methods and technology related to its safety
The Mid-and-Long-term Roadmap states that Technical Prospects will “present measures
toward reducing the volume of solid waste”, “develop analytical and evaluation methods for efficientcharacterization”, and “develop methods to reasonably select safe processing and disposal
methods at the time when the necessary information such as solid wastes’ properties are proven”.
On “present measures toward reducing the volume of solid waste”, the Basic Policy for Solid
Waste specifies that TEPCO should reduce the burden of overall waste management (for the entire
processes, from generation, storage, and processing to disposal) to the extent possible. The
Technical Strategic Plan 2020 takes into consideration the possibility of further efforts based on
precedents in other countries.
“Develop analytical and evaluation methods for efficient characterization” and “develop methods
to reasonably select safe processing and disposal methods at the time when the necessary
information such as solid wastes’ properties are proven” mean to develop and establish themethods necessary for disposing of materials that become waste even after undergoing volume
reduction. The NDF has organized and examined the following specific goals in the TechnicalStrategic Plan 2018. Of the wide variety of types of solid waste, the secondary waste generated bywater treatment, which is highly mobile and for which there is no precedent for processing or
disposing of it in Japan, has been selected as the main object for examination.

34

① Establish a safe and reasonable disposal concept based on characteristics and volume ofthe solid waste generated in the Fukushima Daiichi NPS with its applicable processing
technology, and develop safety assessment methods that apply the features of the disposal
concept, with considering examples of foreign countries.
② Clarify radiological analysis and evaluation methods for characterization.
③ Clarify processing technology which practical application could be expected for stabilizationand immobilization, considering disposal for several important waste streams such as
secondary waste generated by water treatment.
④ Establish methods of reasonably selecting processing technology to stabilize and immobilize
waste based on the above methodology before the technical requirements for disposal are
determined (i.e., preceding processing).
⑤ Have the prospect of setting processing/disposal methods for solid waste for which theprocessing technology considering disposal is not clarified, using a series of methods to be
developed by around FY 2021.
⑥ Clarify issues and measures concerning storage of solid waste until it is conditioned
The following shows the Technical Prospect based on the results of these studies.
a. Approach for volume reduction
If a large volume of solid waste exists, not only does segregation and analysis take time, but the
number of storage containers and the scale of storage facilities increase, and so does the load ofwaste management. Therefore, it is extremely important to reduce the physical volume of solid
waste as much as possible.
At the Fukushima Daiichi NPS, it is important to instill initiatives on volume reduction, aimed atdecreasing the burden of the overall solid waste management, into the overall decommissioning
activities by referring to the examples of overseas countries that have implemented the wastehierarchy concept.
Specifically, the priorities for measures to be taken as waste management are ① prevention ofwaste generation, ② minimization of waste volume, ③ reuse, ④ recycling, and ⑤ disposal. In
waste management, it is important to prioritize ① as much as possible, and consider ⑤ disposal
as the last option for volume reduction of waste to be stored, processed, and disposed of.
In terms of reducing waste generation, it is important to consider in the design and construction
plan to reduce the volume of materials to be used. It is also important not to bring in substancesthat affect processing/disposal as much as possible. To minimize physical volume, considerationon

preventing

contamination

throughstrictsegregation,

maintenance/managementofmanufactures, extension of product life, and waste volume reduction is important. Reuse should
be promoted after contamination checks, decontamination, repair and parts replacement, and it isuseful to consider ease of reuse from the design stage. Considering alternative uses is also
beneficial. In recycling, it is important to consider the contamination condition of contaminatedvaluable sources, separate and process recyclable materials, and use them as new materials andproducts.

35

As shown in Fig. 9, TEPCO has also been implementing initiatives corresponding to this concept.
As new measures to be implemented, among rubble accumulated outdoors (surface radiation dose
rate ≦ 0.1 mSv/h), reuse/recycling of metals, concrete, and scrapped flanged tanks withextremely low surface radiation dose rates are under consideration. As part of this activity,
decontamination methods for recycling metals are being examined. In promoting safe andreasonable waste management, it is important to examine further possibilities based on thecharacteristics of solid waste at the Fukushima Daiichi NPS in reference to precedent cases
overseas.

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.9 Summary of waste hierarchy at the NDA, UK, and countermeasures at the
Fukushima Daiichi NPSb.

Development of analytical/evaluation methods for implementing efficientcharacterization
Since the solid waste at the Fukushima Daiichi NPS is characterized by diverse nuclide

compositions and activity concentrations, and a large physical volume, efficient characterization isrequired. With the aim of developing the analytical/evaluation methods necessary for this purpose,
the Project of Decommissioning and Contaminated Water Management and other initiatives havedeveloped analytical methods for simplified and speed-up data acquisition. Furthermore, as amethod to perform characterization with small analysis data, the R&D program has established amethod for quantifying uncertainties in evaluation values (to identify variable distribution and thewidth) using statistical method with a method for efficiently identifying the inventory in combination
with analytical data and contamination mechanism.
As an analytical method for simplified and speed-up data acquisition, a method employing
automation of pretreatment of analytical samples and the triple quadrupole inductively coupledplasma mass spectrometry (ICP-MS/MS) has been developed, which makes analytical methods
simpler compared to conventional methods using radioactivity measurement. These results will beincorporated into the Building #1 of the Radioactive Materials Analysis and Research Facility underconstruction.

36

As characterization using statistical methods, in addition to using analytical data, statisticalmethods have been applied to the method for efficient characterization by combining with transition
models, resulting in establishing the method to quantify uncertainties in evaluated values. A methodthat combines the Data Quality Objectives (hereinafter referred to as “DQO”) process with statisticalmethods has also been examined/tested to develop a medium-to-long-term analytical plan, and its
effectiveness has been confirmed. In addition, a database called FRAnDLi (Fukushima Daiichi
Radwaste Analytical Data Library) has been created, which contains information related toanalytical data (sample information (type, sampling location, date, etc.) and analytical values ofactivity concentration, etc.), allowing data accumulation on a constant basis.
As described above, analytical/evaluation methods have been developed for efficientcharacterization and will be applied to characterization of solid waste.
c.

Establishment of methods to reasonably select processing/disposal methods
In selecting processing/disposal methods in a reasonable manner, based on the waste

properties, an appropriate combination of processing (waste form) and disposal (disposal facility)
methods should be clarified so that the risk of buried solid waste to the public and environment canbe maintained sufficiently low in the future.
In the case of solid waste from a normal reactor, its properties can be estimated to some extent
by the previous findings (data) or analytical methods. Accordingly, the appropriate combination ofprocessing (waste form) and disposal (disposal facility) methods can sufficiently reduce the risk to
avoid a significant impact on the public and surrounding environment.
Even in the case of solid waste from the Fukushima Daiichi NPS, molten nuclear fuel is a major
source of contamination, and the radioactivity concentration does not exceed that of spent fuel.
Therefore, the risk can be sufficiently reduced by understanding the overall picture of the target
solid waste (properties such as nuclide composition, activity concentration by waste, waste volume),
and selecting a proper combination of processing (waste form) and disposal (disposal facility)
methods, while utilizing the experience and knowledge on radioactive waste processing/disposal
accumulated in domestic and overseas.
However, the overall picture of solid waste to be disposed of, including that which will be
generated, will gradually become clear as the progress and plans for fuel debris retrieval,contaminated and water management, and other decommissioning work are clarified. Therefore, itis necessary to repeatedly examine processing/disposal methods and safety assessments, startingfrom the waste for which properties have been clarified; to give consideration to making
processing/disposal methods more appropriate; and to accumulate knowledge to consider safe andreasonable processing/disposal methods for diverse solid waste collectively. Aiming for safer andnot extremely conservative storage of waste with high mobility such as slurry waste, processing(preceding processing) for stabilization/immobilization may be required before determining thedisposal method (disposal facility). Reprocessing would be necessary if the specifications of thewaste form even after preceding processing did not conform to those required by the disposal
method (disposal facility) to be determined. Therefore, in order to minimize such possibility, aselection method for the preceding processing method with disposal in mind is needed.

37

As mentioned below, study on an appropriate combination of processing and disposal methods,
or preceding processing methods, is considered for the waste for which properties have been
identified to some extent.
⚫

Establish several feasible disposal methods suitable for waste characteristics (without
specifying the feature of facilities such as their locations and sizes)⚫

In parallel, establish several processing methods suitable for waste characteristics to beconsidered, and set the specifications of waste form after applying each processing
method.

⚫

Evaluate the safety of several selected disposal methods based on the specifications ofwaste form after processing to verify whether risk to the public and environment can be
sufficiently low, and to consider more effective processing/disposal methods based on theevaluation results.

The above examination steps are repeated to narrow down disposal methods and specifications
for waste form after processing. Clarifying the overall characteristics of solid waste concurrently
with characterization helps identifying an appropriate combination of processing/disposal. When
preceding processing becomes necessary, candidate processing methods will be selected inconsideration of the status of examination and open issues at that point.
It is also important to consider the period during which pre-disposal management is to be
implemented, taking into account the risk reduction during that period, and examining necessary
and feasible technologies. Since storage is important to provide flexibility to respond to the progressof processing/disposal, and to reduce radiation exposure of workers due to the decay of theradioactive materials, it is important to consider storage strategies as part of this examination
process.
A series of these studies is represented as a flowchart shown in Fig.10. Technical knowledge
and evaluation methods necessary for these studies (establishment of processing technology andwaste form appropriate for waste, safe, reasonable and feasible disposal methods, disposal safetyassessment) have been developed through research/development (verification of applicability ofprocessing methods using engineering-scale test equipment conducted mainly on the secondary
waste generated by water treatment, establishment of safe, reasonable and feasible disposal
methods based on the waste properties and applicable processing technologies, and developmentof safety assessment methods) by the Project of Decommissioning and Contaminated Water
Management, and has been established as a series of methods to select processing/disposal
methods in a reasonable manner.

38

Fig.10 Development of methods to reasonably select safe processing/disposal methods ofsolid wasteii.

Key issues and technical strategies to realize themAfter providing for future issues based on the prospects of a processing/disposal method andtechnology related to its safety, the technical strategies by category to realize them are show below.
Issues based on the Technical Prospects
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.
For the development of analytical/evaluation methods for efficient characterization, it isnecessary to improve evaluation methods and continuously incorporate them into solid waste
management, including processing/disposal, while accumulating analytical data using efficient
analytical methods established through achievements in research/development. In this case,efforts should be made for low-activity waste such as rubble, as well as high-activity waste such as
secondary waste generated by water treatment and waste generated from fuel debris retrieval,according to the characteristics of each type of waste.
To establish methods to select safe processing/disposal methods in a reasonable manner, themethods shown in Fig.10 should be used to proceed with the examination toward the determinationof waste form specifications and manufacturing methods for Phase 3, as specified in the Mid-andLong-term

Roadmap.

Specifically,

throughthesemethods,

the

trial

examplesof

optimization/rationalization of processing/disposal methods will be accumulated by waste stream
according to the progress of characterization and with the assumption of ensuring safety to widelyacquire findings on optimization by waste stream. Moreover, consideration will be given to specify
39strategies for optimization/rationalization of the overall picture covering the entire waste stream,
allowing clarification of approaches toward such purposes. In doing so, 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 the concept of the Best Available
Techniques. As the examination progresses, and the processing/disposal methods for the overall
picture of waste are finalized, it will be important to share the examination process for optimization,such as by sharing the awareness of problems with local communities and society.
Technical strategy by sectorsa.

Characterization
For low-activity waste such as rubble, it is not so challenging to perform the analysis work itself.

However, it takes an immense amount of time to measure entire quantity because of the enormousvolume of waste, and therefore, volume reduction and a corresponding efficient analysis strategy
are needed. For that purpose, it is important to take an approach that efficiently ensures therequired accuracy. In order to achieve this, efficient analyses should be promoted by making themsimplified/speed-up, and inventory evaluation methods that combine the DQO process withstatistical methods be established.
For high-activity waste, sampling and analysis themselves are difficult, and the amount ofanalysis data to be obtained is limited. Thus, inventory assessment based on the transition model
becomes more important. It is necessary to obtain actual sample data such as by the ongoing
efforts for sampling from Cs sorption vessels and its analysis, which are currently in progress. The
application of inventory evaluation methods, which combine the DQO process with statisticalmethods, and the priority of data to be collected should also be considered to enhance the accuracyof the transition 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, and quantitative targets for analysis, etc., and to proceed withanalysis/evaluation accordingly. It is useful to accumulate trial results and verify their validity toestablish a flow from the development of a medium-to-long-term analysis plan using statisticalmethods; analysis and data acquisition; the incorporation of the acquired data into examination ofprocessing/disposal methods and evaluation of the outcome; to the development of the next
medium-to-long-term 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., itis planned to establish the Radioactive Material Analysis and Research Facilities underconstruction, as well as facilities for analysis by TEPCO, allowing characterization of a variety ofsolid waste in parallel. Since the target nuclides, analysis items, accuracy, and the number ofsamples for analysis depend on the target solid waste, a structure should be established based on
the appropriate division of roles and according to the characteristics of facilities.

40

b.

Storage
For storage of all waste, it is important to reconsider measurement items and timing, etc., interms of diverse information for characterization, while acquiring necessary information throughcontinuous monitoring and surveillance of the storage status commensurate with the risks involved.
With regard to high-activity waste, such as waste generated from fuel debris retrieval, the issues
and countermeasures assuming the further expansion of the fuel debris retrieval 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 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.
In considering further possibilities of volume reduction, with an aim to reuse/recycle metals withextremely low surface radiation dose, chemical decontamination (decontamination by phosphoricacid), physical (mechanical) decontamination (steel blasting), and decontamination by melting(decontamination by melting slag), are under consideration as metal decontamination methods forrecycling.
As metal recycling with decontamination by melting slag has already been used in many
Western countries, it is considered a promising candidate technology. Thus, it is important to focus
on the areas where the conditions are different between Western countries and the Fukushima
Daiichi NPS (target nuclides, etc.), and to evaluate the applicability of the method.
c.

Processing/disposal
The objective is to establish safe and reasonable processing/disposal methods for all solid

waste in which diverse waste streams exist, and to widely obtain knowledge for optimizing eachindividual stream. Therefore, it is necessary to continue development/research of processing anddisposal technologies required for the series of studies as shown in Fig.10.
Regarding the processing technology, outstanding issues in low and high-temperatureprocessing technology, for which research/development is promoted, should be addressed. Waste
streams, for which the application of low and high temperature treatment technologies has not been
investigated, will be evaluated as necessary, and performance such as leachability for solidified
substances to be produced will be evaluated. As for low-temperature treatment technology,
consideration is given to transformation of solidified substances as well as inspection methods toverify the possibility of solidification. In the case of high-temperature treatment technology, thefeasibility of the whole treatment 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 treatment. Furthermore, in order to expand
technological options, it is important to examine the possibility of low-temperature solidification after
interim treatment such as steam reforming.

41

Regarding disposal technologies, to establish reliable safety assessment techniques, important
issues specific to solid waste at the Fukushima Daiichi NPS will be explored and identified basedon the understanding of the sensitivity structure of parameters to radiation dose and the long-termtransition behavior of disposal facilities. Then, priorities will be examined and incorporated into
research plans. Development and improvement of the proposed disposal options, that combine adisposal concept proposal with waste to be disposed, will also be promoted in reference to practices
at home and abroad. Furthermore, while improving the reliability of this, group of disposal options
will be examined with a bird-view of all solid waste at the Fukushima Daiichi NPS, after expanding
the target of waste streams, on which trial assessments, will be performed by applying safetyassessment technology. Then, , contributions will be made to considering appropriate measuresfor overall waste management, in coordination with areas other than disposal such as presenting
targets for waste form performance and the accuracy required for characterization.
The main technical issues and plans in the future described in this section are summarized asshown in Fig. 11.
The Mid-and-Long-term Roadmap states that properties of solid waste will be analyzed and thespecifications and production methods of the waste form will be finalized in the third phase. As asystematic approach toward this goal in the first period of this phase, studies will be conducted topresent appropriate measures for overall management of solid waste.

42

Fig. 11 Main technical issues and future plans on waste management (progress schedule)

43

Contaminated and treated water managementi.

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) ALPS treated water currently stored in tanks will be handled in accordance with the basic policy
announced by the government in April 2021.
(Progress)
Excluding the reactor buildings of Units 1 to 3, where circulating water injection is ongoing, andthe process main building and high-temperature incinerator building storing contaminated water
temporarily for purification treatment, the treatment of stagnant water in buildings was completed
in 2020, and the inventory was significantly reduced. However, the hazard potential is still high.
a.

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 also 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 the measures
were taken to approx. 140 m3/day (2020). In order to reduce the amount of contaminated water to
100m3/day or less, roof repair and expansion of facing range are being addressed while adjusting
interference with other decommissioning work. Along with the completion of treating the remaining
water, including ALPS-treated water, at the bottom of the flanged tanks in July 2020, measures andobservation for risk reduction are being implemented through monitoring of groundwater and theharbor.
b.

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 main building and high-temperature incinerator building was completed.

44

It is planned to lower the water level in the reactor building while continuously lowering the subdrain water level 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 (α-sludge)
is increasing. As the particle size distribution and chemical composition of the α sludge at thebottom of the reactor building have been analyzed, it is expected that most of the sludge can beremoved by a filter with an appropriate pore diameter. In order to complete the treatment of stagnant
water in the process main building and the high-temperature incinerator building, moreover,methods for radiation dose rate surveillance or recovery are under consideration 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 forrecovering sludge located on the floor is being studied.
c.

Efforts for stable operation of contaminated water management
The measures against tsunami have been implemented, including installation of tsunami tidewalls in the Japan Trench; closure of building openings; reinforcement of land-side impermeable
walls; and relocation of water collection systems such as sub-drains from the revetment side tohigher ground. As a countermeasure for heavy rain, reinforcement of discharge functions of theexisting drainage, etc. is underway.
d.

Treated water management
For handling water treated with the multi-nuclide removal equipment (ALPS-treated water),discussions by experts, including technical aspects and the social impact, such as reputational
damage, were held at a national subcommittee, and a report was published in February 2020. In
April 2021, based on opinions from a wide range of people through subsequent opinion exchanges
with local governments and agriculture, forestry, and fisheries industries, the Government
announced the basic policy of discharging the ALPS-treated water into the ocean on the premisethat safety will be ensured and that measures against reputational damage will be thoroughly taken,
while TEPCO published “Actions by TEPCO in response to the Government’s basic policy on
disposal of the treated water by multi-nuclide removal equipment”. Currently, the equipment needed
and actions against reputation are under consideration.
ii.

Key issues and technical strategies to realize themIssues in the future treatment of stagnant water in buildingsa.

Prevention of spreading α-nuclides
At the bottom of the torus room of the reactor building, stagnant water containing α sludge andionized α-nuclides exists, and relatively high concentration of α-nuclides has been detected (Fig.
12). These α-nuclides has significantly high effective dose factors when ingested by inhalation, and
it is necessary to suppress this spread to a limited extent. At present, the properties of α-sludge
and ionized α-nuclides are being analyzed, and removal methods for preventing the spread of αnuclides are being studied. However, the chemical form of α-nuclides may change depending onwater quality and coexisting substances. In order to ensure removal of α-nuclides, it is necessary
to collect samples from as many places as possible and to understand the difference in their45

properties. Since α-sludge contains a high concentration of Cs -137, in addition, it is important toconsider measures to reduce radiation exposure dose of workers, maintainability, and secondary
waste.

Sampling Point

Sampling Point

Analysis Date

Sampling Point Analysis Date Concentration

Sampling Point Analysis Date Concentration

SARRY Entrance

SARRY Entrance

SARRY II Entrance

SARRY II Entrance

Analysis Date

Concentration

Sampling Point

Concentration

G1S,G3,G6,G7,H1-H5, H4
N,H6(I),H6(II),J1-J7,
K1-K4,B,B South area
El.8.5m El.33.5m

Concentration

ALPS-treated water tanks

Water
injection
Cs-adsorption apparatus

Sampling Point Analysis Date Concentration

ALPS Exit
Add. ALPS EXIT
Sr-treated water tanks
Concentrated Rw
Sampling Point

Analysis Date

Concentration

Sampling Point

Analysis Date

Concentration

ALPS Entrance
Add. ALPS Entrance*5 : Sampling during residual water treatment in the tank

(Source : TEPCO)*1 : Sampling at 1m from the bottom using sampling apparatus*2 : Sampling at the bottom using sampling apparatus*3 : Sampling at 1m from the bottom using pump
*4 : Sampling at the bottom using pump

（出典：東京電力）
Current measurement results of total alpha nuclides [Bq/L]

Fig. 12 Water treatment systems for stagnant water in buildings and measurement results of total
α-nuclidesb.

Treatment of high-concentration stagnant water
In treating stagnant water in buildings, water at the bottom of the buildings has not been pumped.

Therefore, not only α-nuclides but also highly concentrated stagnant water containing radioactive
materials and salt, which is close to the state immediately after the accident, exists at the bottomof the torus rooms of the reactor buildings. The S/C also contains contaminated water with higher
concentration of radioactive materials and salt than usual stagnant water.
It is necessary to dispose of contaminated water containing such high concentration ofradioactive materials and salt as soon as possible in terms of risk reduction. In order to suppress
the fluctuation range of the contaminated water concentration for the stable operation of the water
treatment system, however, contaminated water of high concentration and that of low concentration
are mixed for treatment. For this reason, in order to accelerate the treatment of highly contaminatedwater, it is necessary to proceed steadily with careful planning that takes into account the waterbalance with low-concentration contaminated water.
Issues of contaminated water management considering the decommissioning process
such as fuel debris retrievala.

Handling of high-concentration α-nuclides
The possibility that fine particles containing high-concentration α-nuclides are produced andmixed into the water treatment system in association with cutting, fabrication, etc., of fuel debris
cannot be denied. Therefore, it is necessary to take measures, such as strengthening themonitoring of water treatment systems, installing collection systems for fine particles containing αnuclides, and monitoring for criticality. Further, in handling such α-nuclides, the chemical
characteristics of actinide elements constituting the α-nuclides needs to be sufficiently understood.
Actinide elements change into various chemical forms depending on the water quality, and the46

dissolution rate tends to increase significantly especially in the oxidizing environment. Therefore, it
is important to understand and control the water quality. When examining the method of removing
α-nuclides, moreover, more effective designing becomes possible by sampling even a small
amount of actual liquid at an early stage and conducting performance verification using samples. It
is necessary to evaluate the safety of recovered high-concentration α-nuclides from the perspectiveof criticality, heat generation, radiation dose, hydrogen generation, and waste management.
b.

System configuration for sustainable stable operation
The water treatment system at the time of fuel debris retrieval needs to secure reactor coolingwater and purify a large amount of radioactive materials containing α-nuclides. Therefore, as awhole system, it is recommended that the cooling water circulation system has a simple system
configuration that focuses on reliability. For the purification system which has a complex
configuration, it is recommended to have a system configuration that takes and purifies a portionof contaminated cooling water, enabling both purification and supply of reactor cooling water. As
for the purification system equipment, it is necessary to consider the evaluation of the volume ofsecondary waste generation and maintainability under a high radiation dose, as well as theevaluation of purification performance, and to examine purification methods in the medium-andlong term. In particular, system planning for the entire purification system equipment should bepromoted with the view to improving and updating existing systems, based on the operation
experience of existing systems, changes in the water quality environment up to the present, andpredictions of changes.
c.

Medium-and-long term measures for contaminated water management systems
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, and examine
the principles of more stable contaminated water management and more appropriate
maintenance/management.
Issues for discharging ALPS-treated water into the ocean
The announced Government policy on discharge of ALPS-treated water aligns with theinternational concept, and is an important decision in terms of ensuring the sustainability ofdecommissioning work. In particular, discharging ALPS-treated water into the ocean enables
reduction of risks associated with tank storage and allocation of limited resources to other high-risk
operations, contributing to the steady progress of decommissioning work.
On the other hand, it is also a fact that there have been concerns about reputational damage dueto the discharge of ALPS-treated water into the ocean. Therefore, efforts should be continued todeepen understanding to eliminate such concerns. The reliability of TEPCO has declined due toinappropriate incidents in terms of physical protection of nuclear materials at the KashiwazakiKariwa Nuclear Power Station and insufficient provision of information during earthquakes at the
Fukushima Daiichi Nuclear Power Station. TEPCO needs to take this reality seriously and respond47

more carefully than before. One of the reasons for this incident might be insufficient communication
with local communities and commercial distributors. Therefore, greater transparency is required,for example, 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 tritium contained in the water to be discharged to the ocean on thehuman body; and (3) the method for verifying the operation status as the basics for implementing
safe offshore discharge, and by verifying these through reliable third parties such as IAEA incooperation with organizations concerned, and by delivering accurate information.

[Conceptual diagram of the discharging system]
Secondary treatment

Site use planning

Conduct secondary treatment, if necessary, toensure that it is below the regulatory limits forreleases to the environment*.

To ensure the stable discharge of ALPS-treated water andproceed with the construction of facilities necessary fordecommissioning, consideration will be given tomeasurement/verification system, replacement tanks anddismantling of storage tanks.

*Total notified concentration ratio is less than 1

Sr-treated water, etc.
(Water before ALPStreatment)

Multi-nuclide
removalequipment[ALPS]

Total notified concentration ratio
except for tritium [1 or greater]

Storage tanks•on premises

Total notified concentration ratio
except for tritium [less than 1]

Waste

The results of measurement and evaluation of theconcentrations of tritium, 62 radionuclides (to be removed by
ALPS), and carbon-14 radioactive in the ALPS-treated water
will be disclosed as needed, and assessments by third parties
and public disclosure will also be conducted.

Measurement/
verification system

Tritium concentration in discharged water

Diluting

Measures in case of emergency

Since it will be diluted with a large
amount of seawater (more than 100
times), the total reported
concentration ratios of nuclides otherthan tritium in the discharged water
after dilution will be less than 0.01.

Treated water analysis

Secondarytreatment
equipment

The discharge will be cancelled, if the facility is
unable to perform its planned functions due tomalfunction or power failure, or if abnormal
values are detected by marine monitoring.

The tritium concentration in the discharged water
should be less than 1,500Bq/L, which is 1/40th of theregulatory limit (60,000Bq/L), and is evaluated by thetritium concentration before discharged and theamount of dilution water.

Emergency
Shut-offvalve

Discharged volume
For the time being, the volume will be within
the range of 22T Bq/year, which was the preaccident emission control target of Fukushima
Daiichi, and will be reviewed as appropriate
according to the progress of decommissioning.

Mix with seawater anddilute thoroughly

Seawater transfer Pump

Discharge into the ocean
Underwater tunnel(approx.1km)
Drainage pit(Monitoring before discharging)(TEPCO material edited by NDF)

Fig. 13 System for discharging ALPS-treated water into the ocean① Operation plans for offshore discharge
The conceptual diagram of the discharge system planned by TEPCO is shown in Fig.13. In thisdischarge facility, the concentration of radioactive materials other than tritium in the ALPS-treatedwater is confirmed to be below the regulatory standard value for the discharge to the environment
in the measurement and verification facilities. Then, the discharged water is mixed and diluted withseawater so that the tritium concentration is less than 1,500 Bq/L, which is 1/40 of the regulatory
standard value (60,000 Bq/L).
Then, the diluted water is planned to discharge into the ocean from the discharge outlet throughan underwater tunnel, as well as to perform marine monitoring. A set of discharge systems covers
from [purification], [analysis/verification], [dilution], [discharge] to [continuous monitoring in the sea
area]. In addition, an emergency shut-off valve is planned to be installed in the process between[analysis/verification] and [dilution] so that the discharge can be suspended in the event of system
failure or detection of any abnormal values during marine monitoring.

48

This discharge system planned by TEPCO is based on the past results in Japan and overseas,and safe offshore discharge will be possible by ensuring that these results are reflected in thesystem, developing operational procedures and manuals for equipment operation and analysis,thoroughly educating, training, and observing operators, and strictly adhering to the implementation
plan. By strictly following the implementation plan, safe offshore discharge will be possible.
② The effects of tritium contained in the water to be discharged to the ocean on the human body
The annual discharge of tritium is planned to be within 22 trillion Bq, a target value of controllingdischarge set by the Fukushima Daiichi NPS before the accident. Tritium is a radioisotope ofhydrogen, and is contained in any water, including water vapor in the atmosphere, rainwater,seawater, tap water, and even in the human body. In addition, its properties are similar to those ofordinary water molecules. As its characteristic, therefore, it is difficult to separate tritium from water.
The impact of tritium on the human body due to the disposal of ALPS-treated water has also been
evaluated using the UNSCEAR method, and it has been confirmed that the impact is extremely
small compared with that of natural radiation (2.1 mSv/yr). TEPCO will review the annual dischargeof tritium according to the progress of decommissioning, etc.
③ The method for verifying the operation status
In the operation phase, it is necessary to confirm that the planned facilities are installed andoperated reliably, that the analysis is conducted reliably in accordance with the establishedprocedures, etc., and to publish the results.
Moreover, it is necessary to increase the transparency of the implementation status of the planby involving third parties other than TEPCO in analysis/verification before the discharge, andmarine monitoring after the discharge. For third-party involvement, it is important to develop aquality assurance system because the results may vary depending on the institution and facility for
analysis due to the fluctuation of the lower detection limit caused by the detection accuracy ofmeasuring instruments or analysis techniques. It is also necessary to consider a structure forverifying the operation status of the developed system.
TEPCO's planned discharge system, if operated reliably in accordance with the implementation
plan approved in the review by the NRA, will have no adverse effects on humans and theenvironment, including other radionuclides, and therefore it is an important issue to operate thesystem "reliably" “as planned”. Going forward, TEPCO will need to proceed with the following
preparations; they include developing of a specific system plans for system and its operation,
education and training on system operation and analysis, etc. for parties concerned, impact
assessment on the human population and the natural environment, development of strategies toprovide accurate and understandable information domestically and internationally, and timely
dissemination of the status of preparations. During actual operation, it is necessary to ensure theimplementation of the plan (system, operation, information distribution, etc.) established in the
preparation stage, to perform check and review, and to review and expand the plan as needed, as
well as to ensure its transparency.
NDF will provide technical and professional support for TEPCO in designing the discharge
system and considering discharging methods, while promoting distribution of accurate information49

and increasing understanding through various opportunities in Japan and abroad in line withchanges in the interests of those who will receive the information. We will also make sure thatTEPCO implements measures to minimize reputational damage, and that TEPCO takes
appropriate and sufficient actions with compensation in the event of reputational damage.
The main technical issues and plans described in this section are summarized as shown in
Fig. 14, and Fig. 8 shows the future plans for the water treatment system for fuel debris retrieval.
Fiscal year
Relatedmilestones
Contaminatedwater generation
amount

2021

2022

2023

2026

To control the contaminated water generation amount to approximately 150 m3/day (in 2020)
To complete the processing of stagnant water in the building (in 2020)

2032(year)

To control the contaminated water generation amountto 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)

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

Site pavement inside the land-side impermeable wall (mountain-side)

Site pavement inside the land-side impermeable wall (sea-side)

Repair broken parts of roofs (incl. the installation of a large cover on Unit 1 R/B)

Stagnant water in buildings

Confirming stagnant
water characteristics

Units 1 to 3
R/B

Water level lowering for a 50% reduction

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

Simple measuresagainst α-nuclides

Designα-nuclides removal equipment
Manufacture and installation

Operation▽ Accomplished in December, 2020

Units 1 to 4
T/B, etc.
Processmainbuilding
Hightemperatureincinerator
building

Measuresagainst stagnant
water

Water level lowering for
exposing the floor surface

Examination of methods for collecting sludge on the floor

DesignConceptual
designManufacturing and installatin of equipment for collecting sludge on the floor

Alternative tank
Manufacture and installation＜Legend＞：The period of on-site work

Measures for zeolite sandbags
DesignManufacture
and installation：Technical study on on-site work

Collection
Water level lowering for
exposing the floor surface：The period in which change is
expected

Removing stagnant water on premises

Dismantling underground water storage tankConceptual study

Design/removal

Fig.14 Key technical issues and future plans on contaminated water management (progress schedule)

50Fuel removal from spent fuel poolsi.

Targets and progress(Targets)(1) While the return of residents and reconstruction in the surrounding area is graduallyadvanced, to carry out a risk assessment and ensure safety including preventing dispersionof 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. To complete fuel removal from SFP in FY 2020 for Unit
3. (Completed in February 2021)(2) 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.
(3) 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, removal of the building cover (remaining parts) that interferes with installation of thelarge covers has been completed, and installation of the large covers is in progress within the area
where the cleanup around the reactor building has been completed. In addition, in order not toaffect fuel in SFPs, measures to prevent and mitigate the dropping of rubble, such as installationof supports for overhead cranes and fuel handling machines, and curing of the SFP, werecompleted in November 2020.
For Unit 2, yard cleanup and soil improvement work are underway as preparatory works for
installing the fuel removal platform. In addition, based on the measurement results of the air dose
rate and surface contamination of the operating floor conducted in March and April 2021,
decontamination of the operating floor is ongoing to further reduce radiation dose.
Removal of all fuel from Unit 3 was completed in February 2021. It is important to roll out theknowledge and lessons learned from this experience concerning procurement and remote control
to planning and implementation of future decommissioning work. Therefore, TEPCO has compiled
internal documents for reference, organizing their results, including efforts for troubleshooting andrecurrence prevention. Moreover, as part of its approaches to strengthen quality control, TEPCO
has revised the “Basic Design Management Manual” common to all Fukushima Daiichi NPS to
improve its design and procurement processes.
For Units 5 and 6, fuel will be appropriately stored in the SFPs of the units for the time being.
Then, they will be retrieved in a range so as not to affect the work in Units 1 and 2.
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 off-site transportation of new fuel.
Such efforts will be made to complete fuel removal in all units in 2031.

51

Key issues and technical strategies to realize themii.

For Units 1 and 2, it is necessary to advance the work steadily to realize the determined new
removal method.
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, although overhead crane support is installed for fall prevention, it is still in an unstablestate. Therefore, removing the overhead 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 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 tothe impact of the explosion at the accident. It is necessary to make a comprehensive decision on
how to handle these well-plugs, and by taking into consideration the impact on the removal of fuelfrom SFP and fuel debris retrieval in the later stage, and by performing thorough safetyassessments.
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 a design schedule with appropriate margins, ② to perform mockup tests fully simulating
on-site situations and operation methods and ensure feedback on the results to design andproduction, and ③ to be sufficiently familiar with the operation and functionality of systems
beforehand in preparation for removal by remote operation.
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.
The main technical issues and plans described in this section are summarized as shown in Fig.
15.
52

2020

Fiscal year
Related milestones

Unit 1

2021

2022

2023

2026

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

Removal ofbuilding cover(remaining parts)

Start Unit 2 fuel retmoval(FY 2024 to FY 2026)

2032(Year)

To complete fuel removal(in 2031)

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

Suspended while
work is performed at
Unit 2

Unit 6 fuelremovalSuspended 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. 15 Key technical issues and future plans for fuel removal from SFPs (Progress schedule)53

4 Analysis strategy for promoting decommissioning
Uncertainty of fuel debris, etc. and importance of analytical results
The accident at the Fukushima Daiichi NPS was the first core meltdown accident at a BWR 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 can be reduced, there is no need to include excessive safety margins in safetyassessments and safety measures, and thus, the promptness and rationality of decommissioning
can be improved. In addition to conventional sample analyses, studies on reducing uncertainty offuel debris properties by other measurement methods have already started by the Project ofDecommissioning and Contaminated 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, should take the lead in establishing and developing analysis systems, facilities,
and functions that can efficiently collect and evaluate analysis results.

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.

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 (facility
management building, building #1, building #2) adjacent to the Fukushima Daiichi NPS under the
supplementary budget of the Government (FY2012). At commencing operations in buildings #1 and#2, they will be designated as controlled areas of the Fukushima Daiichi NPS, which has theadvantage that off-site transportation is not required. Leveraging this, it is effective to promptly
identify basic physical properties, and incorporate them into safety assessment and work54

procedures. The purpose of building #1 is to analyze solid waste, and building #2 is to analyze fueldebris. The facility management building began its operation from 2018, building #1 commenced
comprehensive functional tests from February 2021, and building #2 is undergoing safety review.
However, the operation start of building #1 scheduled for June 2021 has been delayed due to a
malfunction of the air supply/exhaust system. Therefore, it is necessary to examine further
utilization of facilities for analysis in the Ibaraki area and to organize division of roles according to
the characteristics of the facilities for analysis in and near the Fukushima Daiichi NPS and those in
the Ibaraki area. However, since all the facilities for analysis in the Ibaraki area have been in
operation for more than 30 years, considerations on measures are required for aging facilities thatwill be used continuously.
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 shortof the human resources required for stable facility operation, and the securing and maintaining ofanalytical engineers needs to be considered. In this respect, it is necessary to consider in advancethe qualities expected of analytical engineers in various analytical works, and to develop a plan sothat the required roles are appropriately achieved. In order to develop human resources for fields
where there is little experience in as short a time as possible, it is necessary for TEPCO to promptly
work on developing analytical technicians with the cooperation of JAEA and Japan Nuclear Fuel
Limited that have accumulated sufficient knowledge and experience on the handling of α-nuclides
and fuel analysis techniques. Since there are few talented personnel (analysis evaluators) who candesign the analytical range and items in anticipation of how to use the analysis results in advance,
it is also important to make efforts in increasing such personnel.

Improvement of the quality of analysis results, diversification andexpansion of analysis methodsi.

Improvement of the quality of analysis results
Fuel debris contains difficult-to-measure nuclides, interfering elements, insoluble materials, etc.,

and it is considered difficult to conduct complete composition analysis. It is also an important
perspective to question 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, deriving consistent property evaluations in reference toanalysis, surveillance and test results leads to improving reliability of analysis results, and thereby
quality of the analysis results.
Fuel debris caused by the accident is a mixture of fuel and materials in the core. It is important
to comprehensively review/evaluate at what stage of the accident progression the substance wasproduced, what elements were mainly contained, and what properties they have. This also enables
provision of feedback on instructions for necessary sampling to cascade analysis results, insteadof unnecessarily increasing the number of samples to be analyzed. As shown in the conceptual
diagram shown in Fig. 16. it is expected that a flow will be established from [(1) Fuel debris
sampling], [(2) Sample analysis], [(3) Evaluation of the characteristics] to [(4) Safety Assessment]55

and the cycle from [(1) Fuel debris sampling], [(2) Sample analysis], [(3) Evaluation of thecharacteristics] to [(6) Instructions for the next sampling]. TEPCO and JAEA are alreadycooperating in implementing forensic activities that estimate accident behavior and causes bycomparing the results of sample analyses with mock-up testing on progression of meltdown andpast scientific knowledge, and it is recommended to further expand these activities.

Fig. 16 Conceptual diagram from fuel debris analysis to evaluation/countermeasures

ii.

Diversification and expansion of analysis methods in light of sample size and quantity
constraint
The current sample analysis is mainly performed using an electronic microscope after

transporting smear samples to a facility for analysis in Ibaraki area. Since the density, hardness,and other items cannot be measured for micro or small samples, it is necessary to increase thesize and quantity of the samples in accordance with the progress of the fuel debris retrieval process.
It is difficult to analyze a sufficient number of samples because the analysis is performed by using
a manipulator in each process in a hot cell, and by about 0.5 to 1 samples per month in one facility.
Consequently, there is a large gap between the amount to be retrieved/stored and the amount tobe analyzed.
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 awide range of uncertainty in evaluation. It is effective to diversify and expand the analysis methods
and to perform comprehensive evaluation in order to increase good analytical results, regardlessof the restrictions on the improvement of analysis quality and sample quantity. For example, in
addition to performing unsealed sample analysis in a facility for analysis, it is recommended thatin-situ analysis (simplified analysis) and non-destructive measurement are performed to increase
the amount of information on the sample, including coordinating information during collection, and56

to consolidate the results to perform evaluations for controlling the range of uncertainty within acertain level. However, there are no practical examples of in-situ analysis or non-destructive
measurement of fuel debris, and remote operation is required because of the high radiation doseof the subject. Therefore, it is necessary to promote research and development focusing on specificitems such as uranium content.

57

5 Efforts to facilitate research and development
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 imminent, it is necessary
to accelerate research and development in consideration of the practical application for a gradualexpansion of retrieval scale and further expansion of fuel debris retrieval.
In order to solve these technical issues, basic/fundamental research and application researchby universities in and outside of Japan and researching institutions such as JAEA, practicalapplication research and field demonstrations by IRID, manufacturers including overseas
enterprises and TEPCO, etc., are being performed by various industrial-academic-governmental
institutions.
The Government is supporting highly-difficult ones among application research, practicalapplication research and field demonstrations by “the Project of Decommissioning andContaminated Water Management”, and ones regarding basic/fundamental research by “The
Nuclear Energy Science & Technology and Human Resource Development Project (hereinafterreferred to as "World Intelligence Project")”. TEPCO is engaged in technical development directly
leads to practical application. NDF considers R&D medium-to-long term plans, next-term R&D
plans, and promotes these plans and supports the World Intelligence Project. With institutes
involved as its members. Moreover, NDF has established the Decommissioning R&D PartnershipCouncil, which considers information sharing on needs and seeds for R&D, adjustment of R&D
based on the needs of decommissioning work, and issues on promoting cooperation in R&D andhuman resource development. Based on the discussions at this council, NDF set up “a task force
on research collaboration”, and identified six Essential R&D Themes mainly in the area ofbasic/fundamental research to be addressed with priority, in light of investigational issues andproblem awareness on the side of the needs. The R&D implementation system is shown in Fig. 17.

58

Fig. 17 Overview of the R&D implementation system related to the decommissioning of Fukushima
Daiichi NPS

Key issues and strategiesi.

Updating the R&D medium-and-long term plan
In October 2020, NDF and TEPCO developed the R&D medium-to-long-term plan overlooking

the overall research and development for about ten years for decommissioning. The R&D mediumto-long term plan has been updated based on the Mid-and-Long-term Decommissioning Action
Plan 2021 revised in March 2021, Progress in R&D and Prospect of Processing/disposal methods
and technology for waste related to its safety.
In reviewing the R&D medium-to-long term plan, TEPCO, the Agency for Natural Resources andEnergy and NDF have held R&D planning meeting, and also shared the plan with the Ministry of
Education, Culture, Sports, Science and Technology (MEXT) to discuss the required results andtiming, and implementation system, etc.
ii.

Initiatives for the Project of Decommissioning and Contaminated Water Management
The Project of Decommissioning and Contaminated Water Management
The Ministry of Economy, Trade and Industry is providing support through the Project ofDecommissioning and Contaminated Water Management for research and development to solve
technical issues that are difficult to solve in decommissioning.
Since last fiscal year, NDF has been participating in the secretariat to strengthen the functionsof project planning and progress management, while TEPCO jointly applies for issuance incooperation with research leadership and provides project management to incorporate59requirements in terms of actual site applicability. As a result of strengthening this system, project
proposals have been made, which incorporate TEPCO’s on-site needs and actual site applicability
in more detail, and the projects have been executed so that the results of such proposals can beeffectively applied to the engineering work by TEPCO.
While actively participating in this system, it is important for TEPCO to increase their focus on
their own R&D activities, and strengthen their structure. In August 2021, TEPCO has enhanced thesystem to promote the examination and implementation of technology development in the future.
Next-term R&D Plan
In order to support the Project of Decommissioning and Contaminated Water Management,
based on the R&D Medium-to-long-term plan, every fiscal year NDF discusses the research anddevelopment to be carried out in the next two years with the parties concerned at the R&D planningmeeting, and then develops the Next-term R&D Plan . The plan is first deliberated on by the Fuel
Debris Retrieval Expert Committee and Waste Management Expert Committee, 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 Secretariat Meeting of
the Team for Countermeasures for Decommissioning, and Contaminated Water/Treated Water
Treatment, then, The Project of Decommissioning and Contaminated Water Management has been
implemented accordingly.
In considering the next-term R&D plan, it is necessary to evaluate the R&D results to date,moreover, to identify issues that should improve its achievement and issues to be newly addressed,
as well as to identify emerging issues and organize technical issues with a view to the R&D
Medium-to-long-term plan. When identifying the issues, it is also important to identify themexhaustively, to confirm whether each issue is in line with the needs of TEPCO, as the entity
responsible for decommissioning, and to aim for the R&D results to be used for TEPCO’s
engineering.
Research and development implementation system for the Project of Decommissioning
and Contaminated Water Management
The IRID has played a major role in research and development for decommissioning for about
ten 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, and in developing fuel debris retrieval equipment and storage containers.
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 situations, consideration is being given to a structure
for after summer 2023, which is its deadline set by IRID.
In the Project of Decommissioning and Contaminated Water Management, it is important toestablish a proper R&D implementation structure. The continuity of R&D activities that have been
conducted mainly by the IRID should be ensured (including accessing its R&D results), andresearchers/developers should cooperate more closely with TEPCO.

60

iii. Promotion of cooperation between decommissioning sites and universities/
researching institutions
The Nuclear Energy Science & Technology and Human Resource Development Project
As the World Intelligence Project since FY 2015, the MEXT has been promoting
fundamental/basic research and human resource development activities, which contribute tosolving issues such as decommissioning of the Fukushima Daiichi NPS. The project is bringing
together domestic and overseas intelligence from universities/researching institutions, crossing
barriers of the nuclear field, and through close coordination and alignment including international
joint research . From new subjects adopted in 2018, the leadership was transferred from the MEXT
to JAEA/CLADS to strengthen cooperation between JAEA/CLADS and universities, 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,
including these 6 Essential R&D Themes, and identifies the R&D needs and seeds required.
Collaboration between the Project of Decommissioning and Contaminated Water
Management and the World Intelligence Project, and initiatives for business-academia
collaboration by TEPCO
Some basic/fundamental research contributing to problem-solving in on-site decommissioning
have recently obtained outstanding research results mainly in the World Intelligence Project. It is
an important issue to directly apply the results in on-site of decommissioning. At the 9th
Decommissioning R&D Partnership Council held in February 2021, it was proposed that the MEXT
and METI work together to resolve decommissioning issues to further deepen needs-driven R&D.
In response to this, it is important to further strengthen ties by sharing R&D planning meetings andthe results of both projects, and to deepen alignment between the World Intelligence Project and
the Project of Decommissioning and Contaminated Water Management. In this manner, theDecommissioning R&D Partnership Council is required to continuously serve as a generalcoordinator, such as by promoting effective alignment between the R&D seeds and the needs ofthe decommissioning work as the initial task of the Council.
Since FY 2019, TEPCO has also started joint research with universities based on the results of
the World Intelligence Project to discover the technological seeds owned by universities fordecommissioning. The Government, JAEA/CLADS, NDF, TEPCO, and other organizations
involved need to further strengthen their cooperation for better matching needs with seeds andserve as a bridge to share outcomes.
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 technologies and collect basic data, building up research centers,
facilities and equipment, and human resource development.

61

In the building for International Research Collaboration of JAEA/CLADS (Tomioka-machi,
Fukushima Prefecture), universities, researching institutions, industries, etc., inside and outside
Japan form a network and promote research and development and human resource development
in an integrated manner. The “Program for Decommissioning Research by Human Resource
Development” was newly established in the World Intelligence Project in FY 2019. It created a hubof research and human resource development (Collaboration laboratory) in both educational
researching institutions and JAEA/CLADS, and has started R&D and a human resource
development project that connects these organizations by cross-appoint system. It contributes tofunctional enhancement of JAEA/CLADS bases.
For research and development infrastructures as hardware, development and utilization of the
Naraha Remote Technology Development Center of JAEA and construction of the JAEA Okuma
Analysis and Research Center (Radioactive Material Analysis and Research Facility) are ongoing.

62

6 Activities to support our technical strategy
Further strengthening of project management and improvement ofcapability required as a decommissioning executori.

Significance and current status of project management
In order to smoothly proceed with the entire decommissioning project while coordinating andharmonizing, it is necessary to establish a management system in which the organizations involvedin the project work 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: research and development, conceptual design, basic design, detailed
design, manufacturing, on-site installation, inspection, and operation. In addition, the Nuclear
Regulation Authority (NRA) will conduct reviews and inspections, as necessary. In order to carryout 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 proceed with overall consistency under a sophisticated project management
system so that the risks inherent in the projects can be appropriately managed. From thisperspective, TEPCO has been working to build and strengthen its project management system,
and in April 2020, then it was reorganized, and the general framework of the management systemand the structure was established. Examples of major approaches until FY2020 include
strengthening the authority of project manager through reorganization, improving safety and quality
levels, preparing a plan focusing on long term perspective (Med-to-Long-term Decommissioning
Action Plan) and formulating R&D medium-to-long-term plan, etc.
ii.

Key issues and strategies to be strengthened in the future
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. This February, on the other hand, a non-conformance event occurred, where informationon the failure of the seismometer installed on a trial basis in the Unit 3 reactor building of the
Fukushima Daiichi NPS was not shared within the organization, and it was not fixed/restored for along period of time. Although there were no issues with work safety or exposure, etc., a series of
events are receiving severe external criticism. At the Fukushima Daiichi NPS, the management

63themselves are engaged in conversation with all site personnel to understand the organizational
issues behind the events.
In order to establish safety an organizational culture, not only a slogan, it is not enough to justask employees to prepare themselves, but each and every employee needs educational materials
and opportunities to learn about safety in a systematic way.
Owner's engineering capability
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 do so, in addition to project management
capability, TEPCO needs to improve the capabilities that the project executor should have, to
optimize the entire supply chain, specifically the engineering ability that TEPCO, the project
executor, proactively performs as the owner (owner's engineering capability) such as the ability tomake engineering judgments, the ability to evaluate business risks, and the ability to specify orderspecifications. For example, in the evaluation of fuel debris retrieval method selection, it isnecessary to evaluate from the viewpoints of quality (fuel debris retrieval status, safety, etc.), project(cost, time and other visions), and technical feasibility. Alternatively, a project that would previously
have been ordered by a single company can be divided among multiple companies, and TEPCO
can oversee and manage the entire construction. It is also important for the enhancement ofowner's engineering abilities to accumulate and feedback various field experiences, such as bythese activities and the promotion of insourcing to be described later.
Fuel debris retrieval is not a job like the design and construction of a nuclear power plant, where
the finished product is delivered with a performance guarantee. Therefore, unless TEPCO, theexecutor of the project, bears the technical and business risks at the end of the project, the cost
will be astronomically inflated. The fact that the project executor bears the technical risk also meansthat the project executor itself must have the ability to assess the reliability of the functional settingsand engineering design, which requires more technical skills than TEPCO had in the past. Here,the most important point is to incorporate “safety and operator's perspectives” as upstream as
possible in engineering.
a.

Ability to assess and manage process risks
It is fundamental to project management to identify and respond to project risks such as cost,

process, and safety, which have a significant impact on project execution, and to complete theproject within a certain margin of error by making full use of forecasting skills and know-how, while
giving top priority to safety and taking into account the constraints and uncertainties surrounding
the project. It is necessary to complete the project within a certain margin of error in terms of period
and cost. In particular, project risk management for work with high technical difficulty anduncertainty (e.g., fuel debris retrieval) will become even more important in the future.
b.

Acquisition 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 conventional64

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, bothparties 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 a making type project, it is necessary to improve the owner's engineering
capability, such as the ability to concretize specifications, as well as to become familiar withacquisition management, which focuses on acquisition.
c.

Promotion of insourcing
In order to meet the many challenges of decommissioning, it is essential to strengthen

engineering capabilities, and TEPCO is promoting insourcing as a means to achieve this.
“Insourcing” means to develop an ability that enables TEPCO to implement planning, design,
maintenance, and operation on its own. It aims at reducing unreasonableness and waste, further
deepening the level of productivity improvement, and improving the operation quality of TEPCO
employees including the quality of design and procurement. The improvement of these qualities
will ultimately contribute to the improvement of safety. While insourcing is effective for a wide range
of issues, it is advisable to proceed with an awareness of the issues that are expected in the future
to gain more benefits.
Securing and developing human resourcesa.

Securing and developing human resources for smooth implementation of
decommissioning projects① Securing and developing human resources based on the Medium-to-long term humanresources development plan
The development of human resources is essential as a basis for the smooth implementation of
long-term decommissioning projects. For this purpose, project management and engineering
capabilities should be enhanced. In addition, it is important to assume occupational categories, thenumber of engineers and the time required in the future (design, operation, maintenance, chemical
analysis, safety assessment, radiation control, etc.) in light of the Medium-and-Long-term
Decommissioning Action Plan, to summarize them as the medium-to-long term human resources
development plan, and to promote human resources development and securing of staff
systematically.
As an initiative to enhance project management capabilities, TEPCO has given responsibility
and authority to project managers so that they can devote themselves to project management. In
addition to basic education for project management, TEPCO is expanding the efforts such as to
newly introduce training program for systematic learning in accordance with international standards.
As an initiative to enhance engineering capabilities, while collaborating with other electric powercompanies, as well as manufacturers, general contractors and engineering companies, TEPCO
has been making use of the knowledge of external experts including overseas experts, andaccumulating and transferring their technical capabilities and know-how including engineering

65

capabilities. Based on the medium-and long-term decommissioning action plan, measures arebeing considered to develop human resources and to secure personnel, assuming the number ofengineers and the time to be required in the future.
② Secure and develop human resources with a "safety and operator’s perspectives”
It is necessary to secure and train human resources with "safety and operator’s perspectives"
systematically and promptly.
TEPCO recognized early on that it is important to secure and train human resources who arewell versed in the field and have acquired sufficient knowledge of the field to have an "operator’s
perspective”. The “core technologies” required for the decommissioning of the Fukushima Daiichi
NPS have been established, and the “Decommissioning Core Technology Course” has been held
to foster them. Since 2015, the company has been implementing initiatives to improve on-site
capabilities with in-house veteran instructors. In addition to the above general familiarity with the
Fukushima Daiichi NPS decommissioning site and acquisition of on-site knowledge, in case where
special skills specific to the facility or work to be handled are required, it is necessary to secure andtrain personnel with such special skills individually.
b.

Fostering the next generation who will be responsible for the future decommissioningof 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 important to secure solid technicalcapabilities on a constant basis. For that purpose, it is essential to train and secure future
researchers and engineers, and ensure technical transfer. The entire industry, academia, andgovernment should promote initiatives for each stage of higher and secondary education.
For students in higher education, it is important for the industry and higher education institutions
to cooperate and continuously implement activities to promote understanding of the nuclear
industry. For the development of next-generation human resources, it is fundamentally importantthat young researchers/engineers are constantly produced from these higher education institutions.
In particular, the World Intelligence Project by MEXT and JAEA/CLADS has introduced a system
in which students and young researchers are made to be aware of decommissioning as animportant research area, and is engaged in decommissioning research.
It can be said that the mechanism of and implementation by the World Intelligence Project haveproduced some results for researchers and students in higher education institutions. Hereafter, it
is important to implement this project so that the perspectives of decommissioning 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. NDF has held “student sessions” for high school
students, etc. to give thought to the reconstruction of Fukushima along with the International Forumon the Decommissioning of the Fukushima Daiichi NPS (hereinafter referred to as “International
Forum”), Through these efforts, high school students are given an opportunity to think about66

activities to achieve both decommissioning of the Fukushima Daiichi NPS and reconstruction,
enabling them to increase their awareness that decommissioning is an important issue inreconstruction 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 tosecure and develop human resources for the next generation according to their respective roles
and levels.
c.

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, suchas 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.

Strengthening international cooperationi.

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 as"unknown unknowns (don’t know what we don’t know)", long-term project management, andsecuring 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 gain the trust of the international community by disseminating accurate
information on the progress of decommissioning, etc., and to promote decommissioning in a67

mutually beneficial manner that is open to the international community by actively and strategically
returning to the international community the knowledge, etc., gained through the accident 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.
In addition, although the global outbreak of new coronavirus infections is a major obstacle to theabove-mentioned international cooperation, many meetings and events are held online, and Japanhas participated by utilizing the online system. NDF has also been actively utilizing the online
system, etc., to gather the world's wisdom, maintain and enhance the international society's
continuous understanding and interest, and maintain and develop cooperative relationships withinternational community. In the future, it is important to further expand the opportunities forcommunication with other countries by taking advantage of the experience gained so far.
ii.

Key issues and strategies
Integrating and utilizing wisdom and knowledge from around the world
As we move forward with decommissioning, Japan has received support from the international

community through the dissemination of information to the international community andparticipation in international joint activities. More than ten years have passed since the accident,
and it is necessary to continue the mutually beneficial relationship while also working to return the
know-how and results accumulated so far to the internal community.
The difficulty in traveling to and from other countries due to the pandemic outbreak of newcoronavirus infections has become an obstacle to the continuation of such mutually beneficial
relationships. 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 new coronavirus infection, does not dilute relationships with relevantorganizations, experts, and international organizations in other countries. Through a series of theInternational Forums, NDF has collected the wisdom including lessons learned and technologies
derived from decommissioning around the world. It is important to continue to make theInternational Forum an effective opportunity to gather wisdom from all over the world by using theonline system, even in the situation where direct participation from other countries is difficult.
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

68private companies. It is necessary for TEPCO to continue to keep abreast of the latest informationfrom around the world, including the situation in the private sector, and to engage in continuous
communication with these private companies, sharing information on the progress of
decommissioning work and forming an environment in which the necessary technologies can beaccessed when needed.
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. To this end, it is important for the government and otherdomestic organizations to disseminate accurate information on the decommissioning of the
Fukushima Daiichi NPS, considering the fact that more than 10 years have passed since theaccident and the interests of the recipients of the information have changed since the time of theaccident. It is also important to participate in international joint activities and disseminate
information to return the knowledge obtained in the course of decommissioning to the international
community. From the aspect of returning the results, it is important to maintain the level of interest
while responding to the changes in the international community, such as the growing interest in not
only the accident and decommissioning itself but also the application to other issues.
On the premise of ensuring safety and taking thorough measures against reputational damages,some countries, in fact, issued comments expressing concern about the impact on the environmentand questioning the transparency in disposal in response to the Japanese government's
announcement of a policy to discharge ALPS-treated water into the ocean. On the other hand,foreign governments, related organizations, and international organizations that understand thesituation of Japan's decommissioning have issued comments supporting Japan's decision. In
addition, the IAEA announced that it would actively cooperate with the discharge of ALPS-treatedwater into the ocean from a third-party standpoint by dispatching a review mission and supporting
environmental monitoring. These actions are pushing to gain international understanding ofoffshore discharge, and the importance of ensuring transparency and building cooperative
relationships through accurate information dissemination was reaffirmed.
It is important to continue to obtain the understanding and cooperation of the international
community for the steady implementation of decommissioning, including the future discharge of
ALPS-treated water into the ocean, and it is necessary for the government and other relevant
domestic organizations to disseminate accurate and easy-to-understand information. It is also
important for NDF, through various opportunities, to disseminate information that is accurate meetsthe changing interests of the recipients, and to return to the international community the knowledge
obtained through the decommissioning process.

69Local community engagementi.

Significance and the current status of local community engagement
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.
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”),
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 themin a phased manner. With regard to 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 governments, commercial and industrial organizations, and local

70

contractors as well as the prime contractors, paying close attention to the spread of the newcoronavirus infection.
In addition, with regard to ③, in order to build an integrated decommissioning project
implementation system locally, from "development and design" to "manufacturing," "operation,""storage," and "recycling," TEPCO is planning to establish and operate several new facilities in the
2020s (announced on May 27, 2021), so that technologies and products of relatively high difficulty
and importance, which have been ordered outside Fukushima Prefecture, including overseas, canbe completed in the Hamadori region. In particular, with regard to local manufacturing, TEPCO hasestablished a joint venture with partner companies that have a proven track record in the field ofhigh-function products that had to be manufactured outside of the prefecture, the plan is to set up
a manufacturing base in the Hamadori region with the aim of creating local employment, placing
orders with local companies, and promoting collaboration.
ii.

Key issues and strategies
Communication issues and strategies
Misunderstandings, concerns, and rumors caused by the inappropriate dissemination of

information on the decommissioning of the nuclear power plant will lead to a loss of reputation andtrust in the decommissioning of the nuclear power plant not only in the local community but also insociety as a whole, which will not only delay the decommissioning of the nuclear power plant but
also hinder the reconstruction of Fukushima. For this reason, TEPCO needs to continue to takevarious measures to promptly communicate the current status of decommissioning in an easy-tounderstand manner. In this regard, while the impact of the new coronavirus infection are expected
to continue for the foreseeable future, TEPCO will make active use of rapidly developing tools suchas virtual tour programs and online conference systems, and it is also important to strengthencommunication that is possible even in non-face-to-face and non-contact situations, such as byfurther enhancing photo and video content.
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 particular, the disposal policy of the ALPS-treated water has been the subject of anxiety andconcern not only from locally but also domestically and internationally, and local governments andrelated organizations are strongly urged to provide accurate information and take all possible
measures to prevent rumors. In light of these circumstances, TEPCO must do its utmost to
suppress rumors by steadily implementing the measures outlined in the "TEPCO's response basedon the government's basic policy on the disposal of treated-water by multi-nuclear removal
facilities" (released on April 16, 2021), and by making additions and revisions as necessary.

71Issues and strategies related to the creation of a regional industrial and economic basethrough 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. In addition, for “(3) Creation of
new local industries” which will be promoted in the future, it is a relatively large-scale investment
and is expected to have a great economic effect on the Hamadori area. However, as advanced
techniques are required to produce high-performance products, the issue is how to eliminate thetechnical gap between experienced prime contractors and local communities and connect this topromoting active participation in local companies. Therefore, for the time being, it is important tocontinue 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, andother organizations concerned the location and scale of new decommissioning-related facilities,
the schedule from construction to operation, and the status of considering engagement with local
communities in terms of employment, cooperation and order placement, and to proceed with theactivities while gaining understanding and cooperation.
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
last year, 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. At the same time, with regard to human resource development, theFukushima Decommissioning Engineer Training Center of the Fukushima Nuclear Energy
Suppliers Council, which was established 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 be accelerated. It is important to steadily promote thesevarious efforts while responding to changes in the situation as appropriate, and to build a foundation
for local industry and economy through the decommissioning project and to develop local
companies and human resources.
In addition to research and development related to decommissioning, as companies fromoutside the region move into the region and provide technical guidance to local companies, thenumber of engineers and researchers visiting and staying in the region is expected to increase.
Therefore, it is necessary to establish the necessary environment and support system so that suchexternal personnel can integrate into the local community and play an active role as a member ofit. In particular, it is necessary to take into consideration a wide range of functions such as daily lifeand education so that not only single people but also families can live together with peace of mind.

72

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 eachdepartment. 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. It is important to keep
this trend going steadily, while further strengthening the internal structure as necessary.
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.

73

List of Acronyms/Glossaries
Glossary

Description
Amount of radioactive material contained in the risk source (radioactivity,

Inventory

concentration of radioactive material, or toxicity possessed by theradioactive material)

Well plug(Shield plug)

A top cover to screen upper part of Primary Containment Vessel made ofconcrete (It is the floor face of the top floor of reactor building inoperation)

Engineering

Design and other work to apply technical elements to the site

Cask

Special container used for transporting and storing spent fuelSubdrain

Wells near the building

Sludge generated by Sludge containing high level of radioactive material generated by thedecontamination

decontamination device (AREVA), which was operated for contaminateddevice (waste

water treatment from June to September 2011

sludge)SludgeMuddy substance, dirty mud

SlurryA mix of dirty mud and mineral, etc. in water

ZeoliteAdsorbent used to recover radioactive materials such as cesium

Torus room

Fuel debris

A room that houses a large donut-shaped suppression chamber that
holds water for emergency core cooling system.
Nuclear fuel material molten and mixed with a part of structure inside
reactor and re-solidified due to loss of reactor coolant accident condition

Facing (paving)

Covering the ground surface in the power station with asphalt, etc.

Platform

Footing for work installed under RPV inside pedestal

Flanged tankBolted assembly tanks

Pedestal

A cylindrical basement that supports a body of reactor

Manipulator

Robot arm to support fuel debris retrieval

Mock-up

A model which is designed and created as close to real thing to possible74ウェルシールド
Well shield
プラグplug

Operating floor

オペレーティングフロア
Spent階
4th4floor

使用済燃
Fuel
Pool
料プール
(SFP)
（SFP）

Component

機器ピット
Pit

Primary
原子炉格納容器Containment（PCV）
Vessel (PCV)
Reactor
原子炉圧力容器Pressure（RPV）
Vessel (RPV)階
3rd3floor階
2nd2floor

ペデスタル
Pedestal

Vent Tube
ベント管

11st階floor
1st 地下basement
Fl.
1階

Suppression
サプレッション
Chamber(S/C)
チェンバ（S/C）

Torus room
トーラス室

（Courtesy of IRID）

Fig. 18 Structural drawing inside Reactor building（Courtesy of IRID）

Fig. 19 Structural drawing inside Reactor Pressure Vessel (RPV)75