Technical Strategic Plan 2020 for Decommissioning of
the Fukushima Daiichi Nuclear Power Station of Tokyo
Electric Power Company Holdings, Inc.

Overview

October 6, 2020

Nuclear Damage Compensation andDecommissioning Facilitation Corporation
NDF

Table of Contents
1 Introduction .................................................................................................................................. 2
1)

Structure and system toward the decommissioning of the Fukushima Daiichi Nuclear Power
Station......................................................................................................................................22)

The Strategic Plan ...................................................................................................................4

2 Concept on risk reduction and safety assurance for decommissioning of the Fukushima Daiichi
NPS ............................................................................................................................................. 5
1)

Basic concept of the decommissioning of the Fukushima Daiichi NPS .................................52)

Concept of reducing risk caused by radioactive materials......................................................53)

Approach to ensuring safety during decommissioning ...........................................................9

3 Technological strategies toward decommissioning of the Fukushima Daiichi NPS ................. 13
1)

Fuel debris retrieval ...............................................................................................................132)

Waste management ..............................................................................................................29

3)

Contaminated water management ........................................................................................34

4)

Fuel removal from spent fuel pools .......................................................................................37

5)

Utilization of Analysis Results for Smooth Promotion of Decommissioning .........................40

4 Efforts to facilitate research and development .......................................................................... 42
1)

Significance and the current status of research and development .......................................422)

Key issues and strategies .....................................................................................................43

5 Activities to support our technical strategies ............................................................................. 45
1)

Further strengthening of project management and improvement of capability required as adecommissioning executor ....................................................................................................45

2)

Strengthening international cooperation ...............................................................................47

3)

Local community engagement ..............................................................................................48

１

1 Introduction
Almost 10 years has passed since the accident at the Fukushima Daiichi Nuclear Power Station,and the phase of decommissioning work is shifting from the short-term response to the mid-andlong term response. During this period, concrete progress has been made, such as stabilization of
measures at a certain level for contaminated water management that required emergency
responses immediately after the accident, completion of fuel removal from spent fuel pool(hereinafter referred to as “fuel removal from SFP”) in Unit 4 and start of fuel removal from SFP in
Unit 3. At the same time, a significant reduction in the radiation dose within the power station has
been achieved.
In the future, definite measures to retrieve fuel debris, which is the core of decommissioning
work, must be promoted. The government's “Mid-and-Long-Term Roadmap towards theDecommissioning of TEPCO.’s Fukushima Daiichi Nuclear Power Station” (hereinafter referred toas “Mid-and-Long-term Roadmap”), revised in December 2019, clearly states that the retrieval offuel debris will start from Unit 2 by the end of 2021. To achieve this, Tokyo Electric Power Company
Holdings, Inc. (hereinafter referred to as “TEPCO”) announced in March 2020, the “Mid-and-Longterm Decommissioning Action Plan 2020” (hereinafter referred to as the “Mid-and-Long-term
Decommissioning Action Plan”) as the main work process for the overall decommissioning project.
Through this announcement, TEPCO, as a nuclear power operator, has made clear its stance oftaking the initiative in decommissioning in order to materialize complicated and long-term work
prospects and to make the decommissioning project transparent to the local community and society.
In ”Technical Strategic Plan for Decommissioning of the Fukushima Daiichi Nuclear Power
Station of Tokyo Electric Power Company Holdings, Inc.” (hereinafter referred to as “StrategicPlan”), the technical strategy from the Mid-to-Long-term perspective is presented in overlooking
total approach for decommissioning of the Fukushima Daiichi NPS to steadily implement
decommissioning by TEPCO based on the new milestone directed in the Mid-and-Long-term
Roadmap.
Strategic Plan 2020 is characterized by the formulation of

a Mid-and-Long-term

Decommissioning Action Plan, the identification of requirements necessary for considering fueldebris retrieval methods towards the further expansion of fuel debris retrieval, the clarification of
the concept of ensuring safety in decommissioning work, and the strengthening of management
systems in response to the growing importance of research and development.

1) Structure and system toward the decommissioning of the Fukushima Daiichi
Nuclear Power Station
Looking mid-to-long-term decommissioning, TEPCO has reinforced its management structure
for decommissioning operation and shifted to project-based organization to respond each issues
in a strategic manner and to make steady progress of decommissioning operation since April 2020.
In terms of funding, the reserve fund for decommissioning is managed by Nuclear Damage
Compensation and Decommissioning Facilitation Corporation (hereinafter referred to as “NDF”)

2since May 2017 to ensure the immediate decommissioning. In this duty, it was determined that (1).
TEPCO sets aside an amount of funds at NDF every year that NDF determines to be necessary
for the appropriate and steady implementation of the decommissioning and is authorized by the
Minister of Economy, Trade and Industry, (2). TEPCO proceeds with the decommissioning while
withdrawing the reserved funds in accordance with “Withdrawal plan for reserve fund fordecommissioning” (hereinafter referred to as the “Withdrawal Plan”), which was jointly prepared by
NDF and TEPCO and approved by the said minister (Fig. 1).
In this duty, NDF plays even greater roles and responsibilities as the major supervisor andadministrator of the decommissioning project conducted by TEPCO. These include (1) appropriate
management of the funds for decommissioning, (2) maintenance of an appropriate system forexecuting the decommissioning, and (3) steady work management based on the decommissioning
reserve fund system. NDF presents to TEPCO the work targets and major tasks to be included in
the Withdrawal Plan in accordance with “The Policy for Preparation of Withdrawal Plan for Reserve
Fund for Decommissioning” (hereinafter referred to as the “The Policy for Preparation of Withdrawal
Plan”) that was developed based on the Strategic Plan. NDF also assesses the adequacy of
TEPCO’s efforts in the course of jointly preparing the Withdrawal Plan in terms of project execution
including local community engagement (Fig.2).
Nuclear Emergency Response Headquarters (Director: Prime Minister)Council for the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station(Chairperson: Chief Cabinet Secretary)

Mid-and-Long-Term Roadmap

Nuclear Regulation Authority
 Approval of implementation
plan, pre-service inspection,
welding inspection, etc.

The Team for Countermeasures for Decommissioning and Contaminated Water Treatment(Head of Team: Minister of Economy, Trade and Industry)

Progressmanagement

ReportGranting of
project budget

R&D organization

Approve

Apply forapproval

Nuclear Damage Compensation and Decommissioning Facilitation Corporation

 Development of a mid-to-long-term strategy
Withdrawal plan Tech. support for progress management of important
issues (in collaboration)
 R&D planning and progress management

Strategic  Strengthen international partnership

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

 Management of Reserve Fund for
Decommissioning

Reserve Fund for
Decommissioning

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

Monitoring, examination

Report on theoutcome

Minister of Economy, Trade and Industry
Presentation ofimportant issues

Apply for report Progress management of each countermeasure according toMid-and-Long-Term Roadmap

ReportBidirectional dialogue

Local residents and communities

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

Disburse-mentTokyo Electric Power Company Holdings, Inc. (Fukushima Daiichi Decontamination and Decommissioning Engineering Company)
 Contaminated water management, fuel removal from SFP, fuel debris retrieval, waste management, entire site management, etc.
 Through TEPCO's management reform, the funds required for decommissioning should be reserved
Mid-and-Long-term
responsibly (Implementation of new comprehensive special project plan)
Decommissioning Action Plan Detailed measures for facility safety and protection of nuclear fuel material (Development of
implementation plan for specified nuclear facility* TEPCO, a decommissioning project operator, parti cipates 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

3

Government

Mid-and-Long-Term Roadmap*
Proposals for Revise* Continually revi sed based on the progress of programs,
i n the past revised once a couple of years
Next R&D Plan
(The Government-led R&D program on
Decommissioning and Contaminated Water Management)

NDF

Strategic Plan (a nnual)
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

Joi ntly created with NDF a nd a pproved by METI
• Conta minated water management PG• Spent Fuel removal PG• Fuel debris retrieval PG• Wa ste management PG• General management of the site PG• Fa ci lity ma intenance/Operational Management

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

Engineering

Feedback

R&D

Promotion of Decommissioning projectFig.2. Positioning of the Strategic Plan based on the Reserve Fund

2) The Strategic Plan
NDF has issued the Strategic Plan every year since 2015, with the goals of providing a solid
technical grounds for the Mid-and-Long-term Roadmap, contributing to its smooth and steady
implementation and update, and accomplishment of the target shown in “Target map for Reducing
the mid-term risk of Fukushima Daiichi NPS” provided by the NRA, moreover, providing a reliablebasis for The Policy for Preparation of Withdrawal Plan. The Strategic Plan would affect every
year’s revision of the Mid-and-Long-term Decommissioning Action Plan from technical point of view.
In response to the revision of the Mid-and-Long-term Roadmap made at the end of last year, The
Strategic Plan 2020 presents a mid-and-long-term technical strategy that oversees the entire effortsof Fukushima Daiichi NPS to ensure the steady decommissioning implemented by the operator inaccordance with the new target process. In particular, the retrieval of fuel debris, which is a highly
difficult task, is coming very close, and the roles of the government, NDF, TEPCO, research
institutes, etc., have become even greater for the realization of this task. This document also takesthese viewpoints into consideration.
The specific technical strategies in each field are stated from the following chapters.

4

2 Concept on risk reduction and safety assurance
decommissioning of the Fukushima Daiichi NPSfor1) Basic concept of the decommissioning of the Fukushima Daiichi NPS
Concerning the Fukushima Daiichi NPS decommissioning, the basic concept is to continuously
and quickly reduce the risk caused by radioactive materials that do not exist in the normal NPS. In
promoting decommissioning, it is important that, “to ensure the safety of decommissioning work,measures should be taken by considering the balance of risks from a long-term perspective basedon safety characteristics, and a flexible strategy should be considered for risk reduction.”

2) Concept of reducing risk caused by radioactive materialsi.

Quantitative grasping of risk
In the Strategic Plan, the method based on the Safety and Environmental Detriment score(hereinafter referred to as “SED”) developed by the Nuclear Decommissioning Authority(hereinafter referred to as “NDA”) is used to express the magnitude of risk (risk level) for radioactive
materials. In this method, risk level is expressed as the product of “Hazard Potential,” which is used
to indicate the level of impact of internal exposure caused by intake of a radioactive substance into
the human body, and “Safety Management,” which is used as an index to indicate the likelihood of
occurrence of such event.
ii.

Identification of risk source and risk assessment
The major risk sources identified at the Fukushima Daiichi NPS are summarized in Table 1, andthe current condition of the risk levels of each risk source are expressed as Fig. 3, by focusing on“Hazard Potential” and “Safety Management.”
In the Mid-and-Long-term Roadmap, management of these risk sources is broadly classified into
three major categories: (1) Relatively high risks given high priority (stagnant water in buildings andfuel in the spent fuel pools), (2) Immediate risk unlikely, but risk may grow when handling with haste(fuel debris), and (3) Increased risk unlikely in the future, but appropriate decommissioning efforts
required (solid waste such as sludge generated from the decontamination device). Their priorities
are set, and appropriate measures are taken.

Fuel debris
Spent fuelContaminatedwater, etc.

Table 1 Major risk sources of the Fukushima Daiichi NPS
Fuel debris in RPVs/PCVs in Units 1-3
Fuel in SFPs
Fuel assemblies stored in the spent fuel pools (SFPs) in
Units 1-3
Fuel in the
Fuel assemblies stored in the Common Spent FuelCommon SpentStorage Pool
Fuel Storage Pool
Fuel in dry casks
Fuel assemblies stored in dry casks
Stagnant water in Contaminated water accumulated in the reactor
buildings
buildings/the turbine buildings in Units 1 to 4, process
main building and high-temperature incinerator building,5

Zeolite sandbags

Secondarywaste
generated bywater
treatment

Stored water inwelded tanks
Residual water inflanged tanks
Waste adsorption
vessels, etc.

HIC slurry

Sludge generated
from
decontamination
deviceConcentrated
liquid waste, etc.

Rubble, etc.

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

Contaminated structures, etc., in
the buildings

and sludge containing α-nuclides at the bottom ofbuildings in Units 1-3
Sandbags containing zeolite placed on the basement
floors of process main building and high-temperatureincinerator building
Strontium-treated water and ALPS-treated water stored inwelded tanks
Concentrated salt water and residual ALPS-treated waterleft at the bottom of flanged tanks
Spent adsorbents used in the cesium adsorption
apparatus, a second cesium adsorption apparatus, a third
cesium adsorption 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 liquid waste generated by evaporative
concentration of concentrated salt water with further
volume reduction by concentration, and carbonate slurrycollected from the concentrated liquid waste
Rubble with high-dose (30 mSv/h and above) stored in thesolid waste storage facility
Rubble stored in the soil-covered temporary storage
facility and containers (1-30 mSv/h), fallen trees stored in
the temporary storage pool
Rubble stored in outdoor sheet-covered storage (0.1-1
mSv/h), rubble stored in outdoor storage (below 0.1
mSv/h), fallen trees stored in outdoor storage
Structures, pipes, components, and other items inside thereactor buildings and PCVs/RPVs that are contaminatedwith radioactive materials dispersed due to the accident;
and activated materials generated from operation before
the accident

Major risk sources identified at the Fukushima Daiichi NPS are shown in Table 1. However, whenlooking at the overall decommissioning work over the long term, there is waste that existed before
the accident and those that are not adequately controlled in a stable manner although their hazard
potential is not necessarily high. Since the introduction of the Strategic Plan 2019, these issues
have also been presented. In particular, regarding the facilities containing risk sources that had notbeen expressly considered in the past, investigations and examinations are being conducted inconsideration of external events such as earthquakes, tsunamis, and rainwater.

6

Fig. 3

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

iii. Risk reduction strategy(1) Interim targets of the risk reduction strategy
Measures for risk reduction include the reduction in “Hazard Potential” and the reduction in“Safety Management.” The examples of reduction in “Hazard Potential” include the decrease ininventory and decay heat associated with radioactive decay, and changing the form of liquid andgas into a form that is hard to move. To process contaminated water to change into secondary
waste is an example of form change.
The examples of reduction in “Safety Management” include transfer of fuel in the pools to thecommon spent fuel storage pool, and placement of rubble stored outdoors into storage. Of thevarious risk reduction measures, the reduction in “Safety Management” is generally considered tobe easily realized. Consequently, the immediate target of the risk reduction strategy is to bring therisk levels into the “Sufficiently stable management” region (pale blue area) as shown in Fig. 3.
SED is a quantitative indicator of the current status of risks attributable to radioactive materials,
and is an effective method for prioritizing the measures against risk sources. With regard to Fig. 3,
what was changed from last year is that zeolite sandbags were added1 as part of contaminatedwater management after the accident. It was revealed in December 2019 that they would bepresent in a state of high radiation dose in the process of treatment of stagnant water in buildings(For details, see Chapter 3, Item 3).
In the Strategic Plan 2019, zeolite sandbags were identified as one of the major risk sources that
include radioactive materials exists in site of Fukushima Daiichi NPS other than major risk sources.
Strategic Plan 2020 added it to the major risk sources.
17

(2) Basic approach to risk reduction
Decommissioning of the Fukushima Daiichi NPS is a project with considerable uncertainties
involved. To date, the internal status of Units 1 to 3 has been estimated to some extent through thesimulation of the accident development process, estimation of the places with fuel debris by muonbased fuel debris detection technology, placement of investigation equipment into the PrimaryContainment Vessel (hereinafter referred to as “PCV”), dose measurement and video
photographing in the buildings, and others. There was still significant uncertainty, however, toeliminate uncertainties, many resources and, in particular, a considerably long time are required.
In order to realize prompt risk reduction it is necessary to make integrated decisions through aflexible and prompt approach, based on the directions determined with previously obtained
experience and knowledge, and with experiment and analysis based simulation, placing safety as
the top priority, even though a certain extent of uncertainties remain.
As the viewpoint to make these comprehensive decisions, NDF summarizes the following fiveguiding principles:(Five guiding principles)
Safe

Reduction of the risks posed by radioactive materials and ensuring of worksafetyProvenHighly reliable and flexible technologies

Efficient

Effective use of resources (e.g. people, things, money and space)

TimelyTime consciousness

Field-oriented Comprehensive three-reality policy by checking actual site, actual goods, andactual situation

If the five guiding principles are applied to the actual site, it is important to proceed with thedecommissioning operation after greatly emphasizing on safety assurance for the purpose ofprotecting human beings and environment from radioactive materials associated with theoperations, thoroughly conducting radiological consequence evaluation, and taking appropriate
radioprotective measures. (“Safe”)
For 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, while controlling thisrisk 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 condition on-site (“Field-oriented”) will lead to ensuring safety inmedium-to-long-term.
As for the result judged based on these five guiding principles, it is also important to work todisseminate information carefully so that the results of this judgment will be widely accepted bysociety.

83) 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 reactor involved in the accident

is an unprecedented activity that takes place in a special environment different from that of a normal
reactor, and therefore, to ensure safety, following characteristics (peculiarity) in safety should befully recognized.
・ A large amount of radioactive materials (including α-nuclides that have a significant impact oninternal exposure) are in an unsealed state, as well as in unusual and various (atypical) forms
・ The barriers to contain radioactive materials, such as reactor buildings and PCV, areincomplete
・ Significant uncertainties exist in the condition of these radioactive materials and containment
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 there is a concern about further degradation ofcontainment barriers, etc., it is necessary to take measures considering 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 work when considering
the work based on Five guiding principles.
Firstly, with regard to “safety”: There is great uncertainty about the status of radioactive materials
and confinement 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 materials will be handled in an incompletely confined state. Therefore, thestarting point for all reviews should be confirmation of the feasibility of ensuring safety with a wide
range of possibilities (cases) assumed. At the same time, with regard to “safety”, it is important not
to prolong the work period, while paying attention to risk reduction over the entire work period.
Therefore, it is necessary to avoid excessive safety measures and to take optimum safetymeasures (ALARP2). 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 under special conditions such as a high level of radiation, andtherefore, attention should be paid to the feasibility of construction and implementation ofsafety measures on site.

An abbreviation for As Low As Reasonably Practicable. It means that radiological impacts must be
as low as reasonably practicable.
2

9

・ An approach through design alone has limitation due to significant uncertainties.
From the above-mentioned reasons, it is essential to accurately reflect the actual on-site
information into engineering. For this purpose, the views and senses of the individuals andorganizations (operators) that are responsible for the on-site work (including operation,
maintenance, radiation control, instrumentation, analysis, etc.) and very familiar with actual siteshould be highly respected. And their perspectives and judgements directly based on the site (theoperator’s perspective) are important.
In the actual design of the decommissioning work in the project, TEPCO, as the project executor,
should clearly define the “requirements” for the work in advance, and should design specific safetymeasures to achieve them. In doing so, it is essential to reflect “the safety perspective” and “theoperator’s perspective” to respond to the characteristics (peculiarity) of decommissioning of the
Fukushima Daiichi NPS.
(1) Optimization of judgement with safety evaluation as its basis and ensuring thetimeliness in decommissioning
In proceeding with the decommissioning work with an aim for risk reduction, it is most importantto take appropriate safety measures and ensure safety of the work handling a large amount ofradioactive materials that is technically difficult and has significant uncertainties, such as fuel debris
retrieval. Thus, decommissioning work should be carried out by concentrating on “the safety
perspective”. Specifically, when designing safety measures for each decommissioning activity, it isessential to make decisions based on Five guiding principles after conducting a thorough safety
evaluation and confirming that the required safety is ensured.
In addition, as “the safety perspective” unique to the decommissioning of Fukushima Daiichi NPS,
the importance of making progress in the decommissioning work without delay (the importance oftime-axis-conscious action) can be mentioned. Considering high radiation effects that have alreadybecome materialized, and the possibility of further degradation of containment barriers, etc., making
progress in the decommissioning work without delay will significantly contribute to ensuring thesafety of the entire decommissioning process from a mid-and-long term perspective. Therefore,
unlike ensuring safety for normal reactors, which have a certain margin in terms of human, physical,
and financial resources and have low radiological impacts and high stability, it is particularly
required to make rational and time-axis-conscious judgement on making progress in thedecommissioning work without delay and the resource input. This judgement should be made on
the condition that safety is secured and based on the relationship with the overall balance.
(2) Ensuring safety by incorporating “the operator’s perspective”
To ensure that safety measures are truly effective, it is necessary to satisfy the needs from thestandpoint of those who actually perform operations and tasks on site. For this purpose, “theoperator’s perspective” (perspectives and judgements from the standpoint of those who are familiar
with the site and perform operations and tasks on site) is important. In addition to this standpoint,
the Fukushima Daiichi NPS is a facility that has suffered from an accident, and its decommissioning10

requires an unprecedented approach that could be carried out in the special environment such as
high radiation levels, unlike normal reactors. Therefore, when determining the feasibility of safetymeasures on site, special on-site conditions such as high radiation levels and the environment shallbe considered.
In addition, it is important for ensuring safety to complement design by operations including
operating controls and to utilize the information in design obtained through monitoring, analysis,
etc.
ii.

Preliminary implementation and utilization of the obtained information in the laterstagesOn-site conditions of the Fukushima Daiichi NPS containing the reactor involved in the accident

includes considerable uncertainties. If whole operation of large-scale project such as fuel debris
retrieval is to be designed under such circumstances, assumptions of extremely large safety margin
and wide range of technical options will be needed. Thus, extension of work period or risk of rework
will be unavoidable. As a result, feasibility or predictability of the entire project may reduce and that
leads to delay in entire decommissioning, rise in decommissioning cost, or increased radiation
exposure of workers.
On the other hand, considering current environment with already high radiation level, further
deterioration of containment barrier, and the possibility of future major natural events (such as
earthquake or tsunami), it is necessary to improve such risk state and reduce uncertainties as
quickly as possible. Therefore, a “sequential type approach” is important where dividing the wholeoperation is divided into several stages, “operation at first stage” is implemented for which practicalsafety can be ensured, and then the information obtained there is utilized to the next stage. In thisapproach3, the operation proceeds with its safety ensured through monitoring the condition inside
reactor, restricting operational actions and flexible on-site responses4 at each stage of the process.
The information obtained at each stage of operation is utilized in the design of subsequent stages.
This approach allows to reduce uncertainties in the operation of subsequent stage as well as toimprove the reliability of safety assurance and rationalize design.
TEPCO is required to quickly introduce approach like this into actual engineering and project
management. It is important to accumulate experiences that went well or failed acquired in thisapproach. It will lead to steady progress in decommissioning and contribute to ensuring safety indecommissioning the Fukushima Daiichi NPS from the perspective of risk reduction in the mid-andlong term.

The same approach is applied in the UK including the decommissioning site in Sellafield and it iscalled “Lead & Learn”.
4 For example, taking measures including installing nuclear instrumentation system, limiting
processing volume of debris and restricting operations with the control value of radioactive dust
concentration stipulated.
3

11

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 for
local communities, the government (Ministry of Economy, Trade and Industry, Nuclear Regulation
Authority), NDF, TEPCO, and others to cooperate with each other to reduce risks based on theapproach to ensuring safety based on their respective positions. In doing so, it is important toestablish a system for on-going risk monitoring which enables a wide range of people to easily
understand how the overall risks at the site have been continuously reduced through thedecommissioning work. NDF and TEPCO are considering such a system, and TEPCO needs tointroduce such a system in the future.

12

3 Technological strategies
Fukushima Daiichi NPS

towarddecommissioning

of

the

1) Fuel debris retrieval
i.

Targets and progress(Targets)(1) Retrieve fuel debris safely after thorough and careful preparations including safety measures,and bring it to the state of stable storage that is fully managed.
(2) Beginning trial retrieval of fuel debris from Unit 2, the first implementing unit within 2021, thenstart the gradual expansion of fuel debris retrieval and a series of operations timely. Throughthis process, acquire knowledge and experience necessary for the further expansion of fueldebris retrieval in the future.
(3) To further expand fuel debris retrieval, thoroughly examine the result and progress of the fueldebris retrieval from the first implementing unit, through internal investigation, R&D (thegovernment-led Program on Decommissioning and Contaminated Water Management andTEPCO’s voluntary project), on-site environmental conditions. Through this process, study thebest methods of contain, transfer, and store.
(Progress)
According to the Mid-and-Long-term Roadmap, Unit 2 is designated as the first implementing
unit for fuel debris retrieval, and trial retrieval will be started by the end of 2021. After that, theoperation to gradual expansion of fuel debris retrieval will be promoted. For a trial retrieval, theretrieval device is inserted through an existing opening part that leads to the inside of the PCV.
TEPCO has presented the work schedule up to 2031 in the Mid-and-Long-term Decommissioning
Action Plan, and is working according to this schedule.
①Unit 1Since the second half of FY 2020, further detailed information inside PCV is planned to begained by inserting a boat-type access investigation device with diving capabilities (anunderwater ROV) into PCV and investigating the internal status such as distribution of deposits
widely scattered at the bottom of outside the pedestal, presence or absence of fuel debris
involved in deposits, and structures inside the pedestal. In preparation for the start of thisinvestigations, removal of obstacles within the PCV is being promoted while taking measures tocontrol dust dispersion and monitoring dust concentration by considering the change in dust
concentration when opening the inner door at the penetration X-2.
②Unit 2An arm-type access investigation device (a robot arm) is being manufactured (Fig.4), andmeasures to control dust dispersion are under consideration in preparation for the trial retrieval andthe start of internal investigations of PCV by the end of 2021.
A plan to gradual expansion of fuel debris retrieval is also underway, and the retrieval device will13

be improved by increasing the weight capacity and enhancing accessibility while complying withspecifications for the devices for trial retrieval and internal investigations of PCV. The retrieved fueldebris is transferred to the receiving/delivery cells on site and stored in temporary storage
installations. In addition, some of the fuel debris will be collected in the receiving/delivery cells foranalysis and transported to the facility for analysis. At present, the retrieval device,receiving/delivery cells, and temporary storage installations are being designed.
In response to the unprecedented approach to retrieving fuel debris from the first implementing
unit, NDF is considering confirming the actual site applicability of the device and the results of thereview on modifications to the safety system from the viewpoints of safety, reliability, reasonability,
timely, and the field-oriented stance, in accordance with the progress of engineering at TEPCO.

(TEPCO material edited by NDF)

Fig.4 Image of fuel debris retrieval system (Trial retrieval and subsequent gradual expansion offuel debris retrieval③Unit 3

As for Unit 3, due to high water levels in the PCVs, it is planned to gradually lower the PCV
water levels, taking into account the improvement of earthquake resistance of the suppression
chamber (hereinafter referred to as “S/C”) and conducting internal investigations of PCV. The
concentration of radioactivity may be high in the S/C-encapsulated water, and measuresdepending on the water quality in S/C should be taken. Therefore, in the design and constructionof a PCV water intake installation and in the planning of water treatment, activities are under way
to determine water quality by sampling the S/C-encapsulated water.
ii.

Key issues and technical strategies to realize them
Since the research and development necessary for understanding the situation inside the

PCVs and for fuel debris retrieval is still limited, the current design and the plan for on-site
operations related to fuel debris retrieval should be continuously reviewed based on theknowledge that will be obtained in the future. In addition, considerations are given and theresearch and development for fuel debris retrieval is being promoted, which should lead to an
accurate reflection of the outcome thereof.

14

(1) Trial retrieval and internal investigation of PCV, gradual expansion of fuel debris
retrievalWith regard to the trial retrieval, there are uncertainties and difficulties in the development ofrobot arms and the removal of deposits and obstacles due to a limited understanding of theconditions inside the PCV. Therefore, it is important to conduct a mock-up test simulating the sitefrom the operator's perspective, while adequately confirming safety and the actual site applicability
to steadily proceed.
In addition, it is also important for TEPCO to take the initiative in promoting engineering basedon the considerations in (1) to (3) that have been gained from past experience under thestrengthened project management system.
Based on the engineering schedule led by TEPCO, NDF will set in advance the points to be
confirmed, such as the actual site applicability of access devices, results of examinations on
modifications to the safety system, and the safety assessment of dry storage, and will confirm theoutcome of research and development and engineering results from the viewpoints of safety,
proven, efficient, timely, and the field-oriented stance. At Unit 2, while reviews have proceeded
toward the start of a trial retrieval and internal investigations of PCV using the same robotic arm by
the end of 2021, the review process should be proceeded with after ensuring safety by reaffirmingthat safety is most important. Furthermore, due to the restricted attendance of engineers andtechnicians because of the recent worldwide spread of the coronavirus, it is assumed that theplanned work would be more difficult than before, and therefore, more deliberate and carefulattention should be paid to ensuring safety.
Although small in scale, a trial retrieval and internal investigations of PCV are conducted in afundamental form of site construction for future retrieval work, in which an opening will be newly
provided in the PCV to extend the containment barrier outside the PCV. This presents an approachthat enters a new stage. Since the operations are associated with maintaining the containment
barrier function, a review shall be performed with considerable attention to safety in particular, andpreparations, verifications and training shall be made in a more deliberate and careful manner.
The removal of obstacles, a trial retrieval, and internal investigations of PCV, shall be conductedbased on the information obtained on site and the varying site conditions, etc. According to thestate of obstacles actually obtained in the PCV and the internal conditions, the sequence andmethod of removing obstacles, a trial retrieval, and internal investigations of PCV may varydepending on the observation results obtained at that time. Therefore, these activities shall bedeemed as integrated work.
① Promoting the project with a strong awareness of safety from the initial stage
When opening the inner door of the penetration X-2 to conduct Internal investigations of PCVof Unit 1, the dust monitor for monitoring the work reached the control value, and the measures
to control dust dispersion and dust concentration monitoring were carried out by taking sufficienttime. Despite the unknown conditions inside the PCV, these measures were taken by carefully
working while newly obtaining knowledge on dust dispersiveness. Giving more consideration todust dispersion control from the viewpoint of safety at the initial stage of the project will enable
the work to be implemented systematically. To smoothly proceed with the project by utilizing this15

experience, safety assessments should be conducted more often than ever from the initial stageof the examination and the requirements should be defined clearly by considering the actual site
applicability.
② Clarification of quality requirements considering actual site applicability
Based on the experience obtained in the research and development and the TEPCO-led
engineering, development of devices will be carried out for gradual expansion of fuel debris retrieval
and further expansion of fuel debris retrieval. Depending on the amount of fuel debris to be retrieved,
the scale of the device becomes large and stable reliability should be ensured over the long term.
Consequently, it is important to proceed with the development of the devices after clarifying thespecifications such as the functional requirements, in consideration of the actual site applicability
in advance. Quality control of the fuel debris retrieval device is especially important. TEPCO isrequired to proceed with the development of the devices on the premise that TEPCO will ensure
the quality by sorting out the quality level and the basic requirements concerning quality in advanceaccording to the situation at the Fukushima Daiichi NPS.
In addition, it is expected that more and more efforts will be made in the future in considering
the fuel debris retrieval and in the construction work by combining with knowledge and experiencesfrom overseas. In the research and development carried out with overseas companies, etc., wehave experienced several challenges in the process control other than quality control, as well as inunderstanding the design and production capabilities of the suppliers. To exploit overseas
knowledge and experience, more detailed process control must be carried out also by contractors
and their subcontractors.
③ Acquisition and utilization of information during fuel debris retrieval
TEPCO has begun to consider the selection of data to be acquired and the installations foracquiring such data, aiming for gradual expansion of fuel debris retrieval and further subsequent
expansion. This study involves difficulties in overcoming various limitations such as the weightcapacity of the handling equipment, the cumulative dose of the equipment, remote operability,
etc.
Although the on-site situation is uncertain, it is important to acquire data through condition
monitoring, such as instrumentation monitoring and visual observation during the fuel debris
retrieval operation to make simulation-based assessments, and to acquire the parameters to be
used as design conditions for safety systems and various devices. Thus, an approach is required
to link the data to the results of analyses that will be separately conducted, and to utilize them inconsidering the retrieval method and the safety assessment.
In addition, it is necessary to study the methods for storage and control of solid waste
generated during fuel debris retrieval. It is important to collect various samples, improve data,
and repeat analyses and assessments from the viewpoint of contributing to the examination ofprocessing and disposal methods, in addition to the acquisition of data indispensable for
immediate storage and management during the stage of trial retrieval and gradual expansion offuel debris retrieval. For this purpose, the analysis and assessment should be proceeded with ina systematic and flexible manner as required.

16

The most important thing in the debris retrieval work and in the handling of the waste generated
during retrieval is to proceed with the work under strict work safety management.
(2) Further expansion of fuel debris retrieval
To further expand fuel debris retrieval, more consideration should be given to study the
retrieval method from the perspective of the entire Fukushima Daiichi NPS, in association withthe scale-up of operations, devices, and facilities. Since TEPCO is at the stage of making a very
important decision for decommissioning as the project executor, TEPCO is required to set up abasic policy with the perspectives on cost, duration, and total exposure dose, while giving toppriority to ensuring safety, and taking responsibility for carrying out the project. The outcome andinformation newly obtained from R&D and internal investigations should be reflected in the studyof the retrieval method, and an approach has to be taken in a flexible manner considering theretrieval method. In addition, it is important to ensure safety through design and on-site operations,such as reflecting the information obtained from on-site operations in the design of subsequent
stages, based on the concept of proactive implementation and making use of acquired
information in subsequent stages, while paying attention to social aspects such as the impact
attributable to the long-term decommissioning project.
① Study flow of the retrieval method
With regard to further expansion of fuel debris retrieval, consideration will be given to themethods including those for collection, transfer, and storage of fuel debris, by ascertaining the
progress in the fuel debris retrieval at the first implementing unit, Internal investigations of PCV,
research and development, and the on-site environmental improvement, etc. In doing so,
operations, devices and equipment, and facilities will be larger in scale and the scope of
construction will be wider than in the case of retrieving fuel debris from the first implementing unit
(Unit 2). Therefore, much more attention should be paid in overviewing the entire Fukushima
Daiichi NPS, including other work. In addition, due to a wider range of operations to be done andstudies in technical fields to be conducted, consideration should be given to the retrieval methodby continuously gathering international insights. In addition, because of the high dose on site andthe limited understanding of the situation inside the PCVs, the scope of operations will beenlarged. Therefore, it is important to specify the requirements required for operations anddevices more clearly and to proceed with the study of the systematic retrieval method. The study
flow of the retrieval method (conceptual diagram) is shown in Fig.5.
In view of the sufficiency of information and the site conditions, Unit 3 will be able to commence
debris retrieval and obtain information earlier.
By representing a certain unit as a representative one, it will enable advancement ofengineering including study of retrieval method, and earlier obtainment of technical points anditems to be further studied. Utilizing the results in other units will lead to reducing the overall risk
of fuel debris in Units 1 to 3. From the above, it is deemed appropriate to consider Unit 3 as apilot unit.
In this way, while taking a preceding approach at Unit 3, the status of other units and the review
results should be reconfirmed, and the unit under review as a pilot unit may need to be17

reconsidered, depending on the outcome. Even if the first implementing unit (Unit 2) is in theprocess of retrieving fuel debris, the method of proceeding with the fuel debris retrieval shall be
flexibly considered in light of optimizing the overall decommissioning work, for example, bystarting the retrieval from another unit that is in preparation for retrieval.
On-site work such as
retrieval of fuel debris fromthe initial unit and internal
investigations
 New insight obtained from fueldebris retrieval from the initial
unit and internal investigations

Research and development

 Progress in R&D (theGovernment-led R&D programon Decommissioning andContaminated Water
Management, TEPCO’s
independent project)

Status in the improvement of
workplace environment
 Status in the on-site environment(radiation dose, water level in PCV) Various new installations (including
buildings)
Prospects of site securing (planning forremoval of obstacles including rubble),etc.

Evaluation on the review results of the retrieval concept(including the review on the overall concept)

Status of site-wide planning Contaminated water
management
 Plan for solid waste Interference with other works,
etc.

Evaluation on the actual site applicability
 Safety
 Reliable Reasonable Prompt Field-oriented

 Requirements
 The methods of retrieval, accessing, and debris recovery
 Safety system
 Storage, transport and storage facilities, etc.

Comprehensive evaluation
 Comprehensive evaluation from the above perspectives

Fig. 5 Study flow of the retrieval method (Conceptual diagram)② Concept of important requirements for the retrieval method (Boundary conditions)
At present, TEPCO is studying the retrieval method by tentatively setting preconditions forrequirements based on the research and development.
To proceed with the examination of a systematic retrieval method in the future, it is required toreexamine the important requirements related to the determination of a retrieval method (theboundary conditions) among the preconditions established at the initial stage of research anddevelopment based on the information and the results of the analyses that have been obtained tothat point to clearly define the requirements, and to revise them as required. In addition, theappropriateness of the concept of the construction method devised at the research anddevelopment stage should be considered and, with regard to a realistic methods, it is also required
to carry out engineering processes such as a trial manufacture in design, performance verification
by mock-up, design improvement, addition of functions in view of the approach to safety, ancillary
preparatory work, and design of the surrounding installations on a considerable scale.
Based on the basic policy, including the perspective described at the beginning of this section,
when stipulating the requirements and proceeding with the study on retrieval methods, TEPCO isrequired to clearly define the important requirements (the boundary conditions) as the project
executor. The important requirements (the boundary conditions) shall be stipulated based on thesafety perspective and the operator’s perspective, regarding which requirements to be defined asimportant and which level of performance is required.
③ A flexible approach in studying the retrieval method
TEPCO is examining retrieval methods according to research and development. Going forward,
after the aforementioned important requirements (the boundary conditions) are stipulated, it is18required to take a flexible approach depending on the situation, including the review of methods,
according to the assessment of the actual site applicability to be implemented based on the casesof dust dispersion during the opening work of the inner door of the penetration X-2 for the Internal
investigation of PCV at Unit 1, the results to be obtained from future research and development,
and the information to be acquired from a trial retrieval, Internal investigations of PCV, and gradualexpansion of fuel debris retrieval at Unit 2.
In addition to the outcome obtained through these studies, a repetitive and iteration-based
approach will be required in studying by incorporating newly obtained information to verify theappropriateness of the preconditions to be established based on the safety perspective and theoperator’s perspective, and to review the retrieval method based on the results.
④ Ensuring safety through design and on-site operation
Since the decommissioning of the Fukushima Daiichi NPS is an unprecedented approach, theperspective and awareness of those responsible for on-site operations (operation, maintenance,
radiation control, instrumentation, analysis, construction, etc.) are more important than those forconventional reactors. In addition to these, it is necessary to acquire information through on-site
operations such as analysis while conducting trial retrieval, gradual expansion of fuel debris
retrieval, as well as investigations and work, and reflect the information in the next design to ensure
safety.
(3) Continuation of internal investigations, etc., and steady implementation of the Mid-andLong-term Decommissioning Action Plan
Fig. 6 shows the comprehensive analysis and the evaluation results of the distribution of fueldebris, access routes to fuel debris and condition of the structures around fuel debris of Units 1 to3. These results were derived from actual measured values of plant parameters obtained during
the accident, results of the severe accident progression analysis, information obtained by internal
investigations of PCV, and the knowledge obtained through various examinations. Although thestate of distribution may vary, the analysis indicates that fuel debris exists both inside the Reactor
Pressure Vessel (hereinafter referred to as “RPV”) and at the bottom of the PCV. In order to retrievefuel debris from each unit, better understanding of the conditions inside the RPV and PCV throughcontinuous implementation of internal investigations as well as research and development.
The Mid-and-Long-term Decommissioning Action Plan presents the work schedule for trial
retrieval, gradual expanded scale of the retrieval, and further expanded scale of the retrieval, andwill be reviewed and revised on an ongoing basis, based on the knowledge to be obtained throughfuture Internal investigations of PCV, etc. The work schedule should be broken down into more
specific items to realize steady implementation of preparatory work toward fuel debris.
Technical issues and future plans described in this section are summarized as shown in Fig.7.

19

(Created based on “Reference 1 : Water sampling included inside the suppression chamber (S/C)” in Unit 3, The 81st Study on Specified Nuclear Facility Monitoringand Assessment, etc.)

Fig.6 Estimated fuel debris distribution, access route and surrounding structures of Units 1 to 3

20

(4) Technical issues for technical requirements and future plansa. Technical issues for ensuring safety of fuel debris retrieval work

As for fuel debris retrieval, the conditions of fuel debris and containment barriers have significant
uncertainties (unsealed, atypical). It has the safety features that a large amount of fuel debris needs
to be handled in a deficient containment condition under such uncertain conditions. It is necessary
to organize the approach to ensuring safety considering these circumstances and share it withstakeholders.
NDF is currently organizing the approach to ensure safety on the basis of (1) optimizing decisionmaking with safety evaluation as its basis, (2) ensuring timeliness in decommissioning, and (3)complementing design with operating controls, monitoring, analysis, and on-site operation at thetime of abnormalities. Along with organizing the concept of ensuring safety, we are establishing the
key technical requirements to ensure safety during fuel debris retrieval and conducting intensive
study.
① Establishing the containment functions (gas-phase)
We expect that existing safety systems will be able to cope with the retrieval of fuel debris, suchas gripping and suction, 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 that contains radioactive materials,
and generation of short-lived iodine and noble gases if criticality should occur.
In addition to re-scattering of Cs, etc., it is concerned that dispersed fine particles (α-dust)
containing α-nuclides may be generated and the radioactivity concentration in the PCV gas-phasepart may increase. 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, andverifying the appropriateness of the containment function built in the subsequent stage. In theengineering conducted by TEPCO, the improvement of dust monitoring installations inside andoutside the reactor buildings and the study of equalizing or reducing pressure in the PCV using
existing equipment are being carried out based on the outcome of the Government-led R&D
Program on 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 suchas the dispersion of α-dust associated with the work, and the retrieval scale of fuel debris will be
gradually expanded.
In doing so, we are considering establishment of a secondary containment function and study its
necessity, while assuming the possibility of an increasing impact on the surroundings.
② Establishing the 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 the21cooling water containing α-particles from affecting the environment, it may be of great importanceto establish a cooling water circulation/purification system, and a liquid phase containment function.
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, theGovernment-led R&D Program on Decommissioning and Contaminated Water Management has
been promoting research and development. In parallel with this, the establishment of a PCV
circulating cooling system that takes water from the PCV and injects it into the reactor for cooling,which is beneficial in terms of preventing the spread of cooling water containing α particles, wasconsidered in research and development by the Government-led R&D Program on
Decommissioning and Contaminated Water Management.
To establish a reasonable containment function in each phase of the scale expansion of fueldebris retrieval, it is rational to monitor the radioactive concentration of cooling water per phaseand verify the validity of the containment function to be built in the subsequent phase. As with thecontainment function (gas phase), from the viewpoint of verifying/investigating the impact of theretrieval work on the liquid phase, TEPCO, through the engineering work, has been discussing
monitoring of the circulating water system as well as system addition/installation, etc., for the
purpose of reducing the concentration of radioactive materials at the inlet in the existing water
treatment systems according to the results of the Government-led R&D Program on
Decommissioning and Contaminated Water Management. The scale of fuel debris retrieval will be
expanded gradually, based on the results of monitoring changes in the condition of waste fluid
containing α-nuclides. The water level in the reactor building is required to be maintained lower
than the groundwater level to prevent 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 Maintaining the cooling functions
Fuel debris generates decay heat. For example, Unit 2 is estimated to generate heat of up to 69
kW. Currently, the temperature is maintained below 100°C (cold shutdown state) with circulation
cooling by injecting water into the reactor.
In maintaining this cooling 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 thecountermeasures to be taken under the assumption of cooling function abnormalities when eachtask is performed. While essential countermeasures would be to continue cooling by early recoveryof the cooling water circulation system or by flexible countermeasures, etc., it is necessary toevaluate changes in the PCV internal condition based on the time margin in an emergency and to
consider emergency response measures and procedures, etc., including collection of devices.
In addition, during the fuel debris retrieval operation, the processing of cutting fuel debris while
spraying water is conceivable from the viewpoint 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 prepared22

through engineering work in order to carefully promote fuel debris retrieval work while observing
how this work will affect the existing circulating water cooling and purification system, as well as its
cooling function.
However, the possibility should be considered that cooling by 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 remaining amount of fuel debris.
④ Criticality Control
Based on the predicted state of fuel debris at the Fukushima Daiichi NPS, criticality is considered
to be less likely to occur, judging from an engineering perspective. To expand the scale of retrieval,
however, consideration must be given to the possibility of changing the shape of fuel debris. In
reviewing a work plan for fuel debris retrieval, an appropriate control method needs to beestablished to ensure prevention of criticality, and prompt detection/shutdown should criticality
occur.
In the initial phase of fuel debris retrieval work, fuel debris should be retrieved by methods thatwill not significantly change the fuel debris shape or limit the treatment amount. For the phase of
expanding the retrieval scale, technical development is in progress to implement criticality control
according to the increase in the amount of retrieval with a combination of measures such as
preparation for adding neutron absorbers, pre-work subcriticality measurement, and monitoring byverifying the fluctuation in neutron signals around fuel debris.
⑤ Ensuring the structural integrity of PCVs and buildings
As for the main devices in the PCV/PRV pedestal, etc., and reactor buildings, their structural
integrity has been evaluated in post-accident studies by TEPCO and the Government-led R&D
Program on Decommissioning and Contaminated Water Management. As a result, it has been
confirmed that the main devices and reactor buildings have a certain level of seismic margin.
Hereafter, the existing main devices and reactor buildings, as well as devices/systems(hereinafter referred to as “systems”) and buildings (including modified areas of the existing
systems and building) 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 level of 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 Internal investigations of PCV and debris analysis results,
etc., to the design of fuel debris retrieval systems and the study of retrieval methods.
Furthermore, with further progress in designing, the loading conditions (layout, size, weight of
the new systems, new openings on PCV/biological shielding walls, etc.) during fuel debris retrieval
will be specified. In order to ensure the structural integrity of systems and buildings, while reflecting
the site conditions, promotion of steady examinations will be required based on the latest design
information.
⑥ 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 and access routes.
23

As a related operation to fuel debris retrieval, removal of equipment with high radiation doses isplanned, in which reduction of exposure during operation is an issue.
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, concerning the reduction of radiation exposure of workers in the reactor building, it
is important to conduct sufficient investigations on the dose distribution and contamination
conditions, including the contribution of the surroundings of work areas, to identify source locations
and intensity to the extent possible, and to develop a plan for radiation dose reduction that defines
the target dose rate in light of the margin for the legal radiation exposure dose limit for workers. Inhigh radiation dose areas, planning is important to reduce the total radiation exposure dose to as
low as reasonably achievable with respect to work hours in accordance with dose limits andrequired work hours to accomplish operations.
Management methods and systems will be required for α-nuclides in a series of work processes
that are capable of containment and leakage detection in preparation for diffusion in the air and thewater treatment system. To further expand the retrieval scale, a database or the like should beestablished to share information and promptly provide feedback to the next work plan. In addition,adequate radiation exposure control should be implemented after formulating a long-term work
plan so as not to concentrate workers’ radiation exposure on individual workers and to help reduceoverall worker radiation exposureb. Technical issues related to fuel debris retrieval methods① Securing access route
For transporting, installing, and unloading the 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 construct
the access routes to fuel debris, it should be kept in mind suppressing of the release of radioactive
materials from the PCV and RPV and integrity maintaining the existing structures.
Toward a trial retrieval and gradual expansion of fuel debris retrieval, TEPCO is currently
proceeding with specific engineering studies to conduct an access route from penetration X-6 at
Unit 2.
On the other hand, in order to further expand the retrieval scale, the construction of an accessroute from the side opening of the PCV to fuel debris is under consideration based on the resultsof research and development by the Government-led R&D Program on Decommissioning andContaminated Water Management. The issue for the access route construction is to addresscontainment, shielding to connect structures between newly installed heavy structures and theside-opening of the PCV, and seismic displacement. As for the upper access method from theoperating floor, the Government-led R&D Program on Decommissioning and Contaminated Water
Management is currently examining improvement of throughput by applying a method to retrieve24and transport interfering structures as a single or large unit while ensuring containment andshielding.
In the future, based on the above-mentioned tasks, it is necessary to clearly define the accessroute to be built in the next phase from the data obtained in each phase, and it is important topromote research and development for scale expansion.
② Development of devices and equipment
Devices and equipment for fuel debris retrieval should be developed with a focus on safety,
reliability, and efficiency. In order to flexibly respond to the situation on site, devices and equipment
must consider radiation resistance, maintainability, remote operability, high reliability, relief
mechanisms that do not disturb subsequent work if trouble occurs, and efficiency of fuel debris
retrieval.
The devices for trial retrieval and gradual expansion of the retrieval scale are under development
as part of research and development activities by the Government-led R&D Program on
Decommissioning and Contaminated Water Management. After the gradual expansion of fueldebris retrieval, TEPCO needs to take over and substantiate the development results. TEPCO isproceeding with the engineering of robot arms, etc., to be applied to Unit 2, while preparing
education/training for the operation of fuel debris retrieval using these remote devices.
As for devices and equipment for further expansion of fuel debris retrieval, development isunderway for construction methods for improving efficiency, retrieval/handling systems according
to diverse conditions of fuel debris, and dust collection systems for dust generated during fueldebris crushing.
As for how to proceed with development, it is required to continue development for emerging
important issues based on the information obtained from preceding investigations and retrieval
work. The developed devices and equipment need to be verified continuously through mockup tests
to confirm that they can demonstrate safe and reliable performance at the actual site. Mockup
testing should be performed in a facility that simulates a harsh on-site environment with major
uncertainties. To achieve this, the NDF and TEPCO are considering how to proceed with remote
mockup test planning.
③ Establishment of system equipment and working areas
Assuming to ensure safety functions, and considering avoiding excessive system specifications,
it is required to examine the establishment of system installations, etc., take necessary measures
such as system additions based on the results of such examinations, and then to operate themproperly. In examinations, 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 equipment include a negative pressure control system required for establishing acontainment function (the air phase), a circulating water cooling/purification system required formaintaining the containment function (the liquid phase) and cooling function, 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 conditions is a25significant issue, which is essential for fuel debris retrieval. In order to build safety systems
incorporating the above, TEPCO has been examining through engineering work. The working area
required for installing fuel debris retrieval equipment/related devices and system installations is
now being calculated. Considering the handling of high radiation dose areas in the reactor buildings
and interference with other tasks, study of setting up the systems, including outside of the existingbuildings, is underway.
c.

Technical issues related to safe and stable storage of fuel debris① Handling of fuel debris (collecting, 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 subcritical condition, containment function,
countermeasures against hydrogen generation, and cooling. The following examinations are in
progress accordingly.
・ Development of basic specifications for containers (total length, inner diameter, etc.), planning,
and implementation of structural verification testing for containers
・ Examination of a practical prediction method for hydrogen gas generation from fuel debris,consideration on specifications of the exhaust structure of containers, and study on safe
transfer conditions based on examination results
・ Drying technology development applicable to fuel debris, and study on a drying system using
this technology
In the future, based on the results of these studies, specific systems and devices/installations forcontaining to storing fuel debris should be developed with consideration of the amount of fuel debris
retrieval per day, the container filling rate, and in coordination with other associated projects. In
developing the specific facilities and systems for containing and storing retrieved fuel debris, it isalso necessary to include responses to safeguard requirements.
It is important to reflect various measurement data collected and accumulated during the gradually
expanded-scale retrieval, such as the amount of generated hydrogen, as well as knowledge andexperience on handling fuel debris during the operations from receiving containers for on-sitetransportation to temporary storage, into the design of equipment and facilities for containing,transporting, and storing fuel debris safely, reliably, and reasonably at further expanded scales ofretrieval.
The Mid-and-Long-term Roadmap stipulates that the processing/disposal method of theretrieved fuel debris shall be investigated and fixed during the third phase after starting the fueldebris retrieval work.
② Classifying of fuel debris and radioactive waste during fuel debris retrieval
In each operation phase from fuel debris retrieval, preparations for that to cleanup, etc., obstacles
and structures, etc., with nuclear fuel materials attached or fused will be retrieved in addition to thefuel debris. For this reason, it is recommended to develop criteria for sorting fuel debris andradioactive waste, and measurement techniques required for sorting.
Prior to fuel debris retrieval, however, it is practically difficult to accumulate, organize, andanalyze sufficient information necessary for sorting, such as the distribution of fuel debris and26

structures in the PCV and their geometry. Therefore, it is recommended to aim for sorting fuel debris
based on the measurement results of the amount and concentration of nuclear fuel materials. As afirst step in addressing this, a survey was conducted on which work processes should be performed
for sorting up to storage (scenario review) and on techniques that may be able to measure theamount and content of nuclear materials. According to these studies, it was considered difficult at
present to measure or estimate the mass and concentration of nuclear fuel materials contained in
the objects to be retrieved from the PCV.
However, it is expected that development of sorting criteria and necessary measuring
techniques/devices for fuel debris and radioactive waste in preparation for a further expandedscale retrieval will contribute to achieving reasonable and safe decommissioning, such as byallowing reduction in the physical amount of materials to be stored as fuel debris. For this reason,
it is recommended to continue development of criteria for sorting fuel debris and radioactive waste,
and measurement techniques/equipment required for sorting. It is also important to continue
activities to enhance the practical applicability of sorting methods/techniques and their efficiency
by leveraging knowledge and information, including sample analyses to be gained from plannedinternal investigations, trial retrieval, and gradual expansion of the retrieval scale.
③ Examining safeguards methods
Material accountancy and safeguards to be applied to the retrieved fuel debris are
unprecedented, TEPCO may face technical issues in examining and applying them to the site. In
response to that, NDF will support the examinations aimed at solving such technical issues froman engineering viewpoint, and will share information on the progress of the project with TEPCO inorder to ensure that system arrangements related to the application of safeguards do not affect thedecommissioning process.
The main technical subjects and plans described in this section are summarized as shown in Fig.
7.

27

Short term (approx. 3 years)
Period 3 - (1) (Starting from fuel debris retrieval up to the end of 2031)
Fiscal Year

2020

2021

Gradual expansion of fuel debris
retrieval(Unit 2)

2025

▽Start of the fuel debris retrieval in theinitial unit (by the end of 2021)

RM milestones

Trial retrieval(Unit 2)2022

Improve the environment
inside the building

On-site operation: Work period: The period during whichchang e is expected
Technical studies on individual items relating to on-site construction

Experimental retrieval and internal
investigations

Manuf acture and install the
retrieval device

2031 (Year): To be conducted as required

R&D

Technical issues in the Government-led R&D program on
Decommissioning and Contaminated Water Management

Characterize the fueldebris
Improv e the env ironment
inside the building

Fuel debris retrieval facility/safety system/fuel debris temporarystorage f acility/maintenance facility
Design and production

Gradual expansion of retrieval scale

Installation

Characterize the fuel debris

Review of the program on
Decommissioning and Contaminated
Water Management andTEPCO'voluntary project- Development of Technology for
Detailed Investigation inside PCV- Development of technologies forgrasping and analyzing propertiesof fuel debris- Development of technology forgradually expanded-scale retrievalof fuel debris
Technical study by TEPCO- Fuel debris characterization/Development of analysis
technology(1) Advancement of fine particle (dust) behavior
estimation technology(2) Estimation of aging properties- Development of technology for gradually expanded-scale retrieval of fuel debris(1) Addressing payload growth and upgrading end tools(Trial manufacturing of arms/enclosures --> Use them as a mock-up during training)

Improvement of the environment inside and outside the Unit 1 building (Inside of the building: Dose reduction/removalof obstacles; Outside of the building: Removal of exhaust tow ers of Units 1 and 2/removal of transf ormers, etc.)

Further expansion of fuel debris Improvement of the environment inside and outside the Unit 3 building(Inside the building: PCV w ater low ering/dose reduction; Outside the building: removal of the exhaust tow ers of Units 3 and 4, removal of transformers, etc.)
retrieval(Units 1 and 3)
Fuel debris retrieval facility/safety system/fuel debris storage facility/maintenance f acility *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 and Contaminated
Water Management and TEPCO's
voluntary project- Development of technologies toretrieve fuel debris and internal
structures toword further expansionof retrieval- Development of Technology forCollection, transfer and Storage ofFuel Debris- Development of technology forinvestigation inside the RPVTechnical study by TEPCO- Development of technologies to retrieve fuel debris and internal structures, addressing
a further scale expansion- Development of technology for investigation inside the RPVConstruction method by top/side/bottom-access(1) Development of fuel debris retrieval method (ensuring safety --> higher efficiency)
a. Improvement of installations and devices for access/technology for removing
obstacles/internal audit methodb. Preventing the spread of radioactive materials(1) Technology for removing obstacles, etc, Access device(2) Development of safety systems (liquid and gaseous systems, criticality control)a. Enhancement of the containment of radioactive materials; b. Enhancement of
the removal of radioactive materialsc. Enhancement of criticality prevention/criticality monitoring functions(2) Surveillance devices (camera, radiation detector,
experimental retrieval device, etc.)(3) Preventing the spread of radioactive materials* It is assumed that Unit 3 w ill be examined in advance and expanded to Unit 1.

Fig.7 Technical issues and future plans on fuel debris retrieval (progress schedule)

282) Waste managementi.

Targets and progress(Targets)(1) The Solid Waste Storage Management Plan (“Storage Management Plan”) is appropriately
developed, revised and implemented including waste prevention, volume reduction andmonitoring, with updating the estimated amount of solid waste to be generated 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 a processing/disposal method andtechnology related to their safety should be made clear by around FY2021.

<Key Points of "Basic Policies on Solid Waste">(1) Thorough containment and isolation
Thorough containment and isolation of radioactive materials to prevent theirdispersion/leakage and human access to them, in order not to cause harmful radiation
exposure.
(2) Reduction of solid waste volume
The amount of solid waste generated by decommissioning is reduced as much as possible.
(3) Promotion of characterization
Proper characterization addressing an increase in the number of analysis samples toproceed with study on processing/disposal method of solid waste.
(4) Thorough storage
Generated solid waste should be stored safely and reasonably according to characteristics
of solid waste. 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 select a method of the preceding processing before technical requirementsof disposal are established.
(6) Promotion of effective R&D with a bird’s-eye-view of overall solid waste management
To confirm required R&D tasks after cooperating with each field of R&D for characterizationand processing/disposal and overviewing the overall management of solid waste.
(7) Development of continuous operational framework
In order to continue safe and steady solid waste management, the continuous operationalframework including development of relevant facilities and human resources must be
undertaken.
(8) Measures to reduce radiation exposure of workers
Radiation exposure control, safety management and healthcare programs should be
implemented thoroughly based on the relevant laws/regulations.

(Progress)
Since a large amount of solid waste with various characteristics is generated in association withdecommissioning of the Fukushima Daiichi NPS, a flexible and reasonable waste stream (the flowof the measures united from characterization to processing/disposal) is being developed in addition29

to improvements in characterization analysis ability. Specifically, the related organizations arepromoting efforts based on each role in accordance with the fundamental view for solid waste
arranged in the Mid-and-Long-term Roadmap, and NDF is taking the initiative to advance thetechnical examination for measures united from characterization to processing/disposal of solid
waste.
(1) Storage
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.
Based on this plan, TEPCO decided that any outdoor storage of solid waste, excluding
secondary waste generated by water treatment and re-use/recycle objects, would be eliminated by
the end of FY 2028, and TEPCO is promoting the arrangement of the required system. The
concrete rubble which dose level is corresponding to it of the background of the site is being
recycled as roadbed material from the standpoint of reducing the waste generation amount. The
recycle and re-use of the metal, concrete, and dismantled pieces of flange tanks with a very low
surface dose is being studied while they are temporarily stored outside solid waste storage facilities
for the time being.
Secondary waste generated by water treatment is planned to be transferred to store in a building,and large waste storage building is being constructed as a storage facility for adsorption vessels.
Also, the slurry generated in the Multi-nuclide Retrieval Equipment, etc., and the waste sludge havea comparatively high risk in storage and management due to high mobility. Stabilization(dehydration) treatment will be carried out for the slurry (operation will start in FY 2022) and transfer
will be carried out from the underground storage tank in a building, the present storage area to highground for the waste sludge (to be completed in FY 2023).
For waste generated in association with fuel debris retrieval, the type and amount of materials
are evaluated, and studies are being carried out for the storage method, the storing method, andthe specifications for containers including measures against hydrogen gas generation, are being
carried out in the Government-led R&D Program on Decommissioning and Contaminated Water
Management.
(2) Study on the processing/disposal measures
With regard to the processing/disposal approach to solid waste, the Mid-and-Long-term
Roadmap specifies that the prospects of a processing/disposal method and technology related toits safety should be made clear by around FY2021. The overall picture of solid waste becomes
clear step by step according to the progress of the effort. Keeping it in mind that it will still remain
in a stage of accumulating necessary information on its characteristics around FY2021, theconcrete targets for technical perspective are listed as follows:Establish safe and rational disposal concept based on characteristics and volume of the solid
waste generated in the Fukushima Daiichi NPS with its applicable processing technology, anddevelop safety assessment method reflecting features of the disposal concept, withconsidering examples of foreign countries.



Clarify radiological analysis and evaluation method for characterization.
30

Clarify processing technology that could be expected to introduce the actual equipment forstabilization and immobilization considering disposal for several important waste streams suchas secondary waste generated by water treatment.



Establish method of rationally selecting processing technology to stabilize and immobilize
waste based on the above methodology although the technical requirements for disposal are
not determined (i.e. preceding processing).



Have prospect of setting processing/disposal measure for solid waste of which the processing
technology considering disposal is not clarified, using a series of methods to be developed byaround FY2021.

Clarify issues and measures concerning storage of solid waste until it is conditioned
To achieve these matters, the applicability of various processing methods (thermal/non-thermal

processing) using engineering-scale testing equipment, etc., is being confirmed, the disposal
concept based on the characteristics of the waste and applicable processing technologies is being
established, and a safety assessment method is being developed, through the Government-led
Program of Decommissioning and Contaminated Water Management.
Also, to effectively understand the characteristics of solid waste required for the study, simplified
and speed-up analysis methods, analysis ability improvement focusing on the arrangement ofRadioactive Material Analysis and Research Facility Building 1 in which waste samples with a low
dose will be analyzed, and accuracy improvement of the analytical inventory estimation method
are being advanced. Sampling and analysis are being carried out for rubble, contaminated water,
secondary waste generated by water treatment, and so on, and the correlation of the nuclide
composition for each analyzed waste is becoming clear gradually.

ii.

Key issues and technical strategies to realize them

(1) Promotion of characterization and enhancement of analysis systems and technicalcapabilities
Human resources development for radiological analysis, and transfer/strengthening, technicalcapabilities on analysis, are important issues in addition to the improvement of facilities to promotecharacterization steadily. For the time being, it is important to proceed with human resources
development for analysis systematically, as well as to proceed with the arrangement of theRadioactive Material Analysis and Research Facility and the reflection of results, such as simplified
and speed-up analysis methods.
(2) Storage
Since the measures against hydrogen generation become an issue in the safe storage of highdose waste, the concepts for a container with a vent and drying technologies are being studied.
Also, since integrity evaluations of storage containers becomes an issue when storage is prolonged,
the study, such as the evaluation method and the measures against the generation of corrosion, isbeing advanced.

31

(3) Development of processing/disposal concept and safety assessment method
In order to select candidate technologies for preceding processing methods, the selection ofreasonable and feasible processing technologies and the development of suitable safetyassessment methods for disposal corresponding to it will proceed.
For the selection of processing technology, it is necessary to confirm the technical feasibility as
the whole processing system, including a supply system and an exhaust system, in addition to theconfirmation of the feasibility of solidification. Also, the required items and information are collected
and arranged to develop a safety assessment method for disposal.
Furthermore, concerning the disposal approach, various possibilities will be studied using
overseas examples as reference, due to the fact that the waste from the Fukushima Daiichi NPS
is large in quantity, having various properties, and showing characteristics of having large
uncertainties.
(4) Examining further approaches based on the view of the waste hierarchy
Many measures are being implemented based on the concept of the waste hierarchy (desirable
approaches in the order of (i) waste prevention, (ii) waste minimization, (iii) re-use, (iv) recycling,and (v) disposal) in the UK and the USA (Fig. 8). The measures based on this concept are being
practiced at the Fukushima Daiichi NPS as well. Further possibilities will be studied based on
preceding examples in other countries in advancing reasonable waste management.
With regard to the prospects of a processing/disposal method and technology related to its
safety based on the results of these efforts, should be made clear by around FY 2021 as the target
based on the results of R&D and TEPCO’s engineering achievements, etc.
Technical issues and future plans described in this section are summarized as shown in Fig 8.
Summary of the Waste Hierarchy(Concept of waste hierarchy)
Waste Prevention(Control of amount generated)
Waste Minimisation(Minimization of waste amount)Preferred
Approach(Preferred approach)

Re-use of Materials(Re-use)Recycling(Recycling)

Examples of countermeasures at the
Fukushima Daiichi NPS
Installation of a vehicle service station, prevention ofcarrying in packing material, and common use of
construction equipment

Classification, separation, etc., of waste

Examination of re-use of metals, concrete, anddismantled pieces of flange tanks with a very low
surface dose
Application of volume reduction equipment (anincineration system, a crusher, and a metal cutting
machine)Disposal(Disposal)

Fig. 8 Summary of waste hierarchy5 at the NDA, UK, and countermeasures at the Fukushima
Daiichi NPS

5

The figure is based on NDA, Nuclear Decommissioning Authority Strategy Effective from April 2016(2016), p.60, Figure 7. Summary of the Waste Hierarchy.

32

Fig.9 Main technical issues and future plans on waste management (progress schedule)333) Contaminated water managementi.

Targets and progress(Targets)(1) Under three basic policies for the contaminated water problem (“to remove” a contamination
source, “not to make water accessible” to a contamination source, and “not to leak” contaminatedwater), to reduce reactor building stagnant water in FY 2022 to FY 2024 to about the half of theamount of the end of 2020 while continuing the operation of the constructed water-level
management system and controlling the generation amount of contaminated water to 100 m3/day
or less in 2025.
(2) To arrange the relationship of fuel debris retrieval, etc., which will become serious from now on,
with a decommissioning process and to promote the examination of the principles ofcontaminated water management for mid-and-long-term prospects.
(Progress)
In order to complete the treatment of stagnant water in buildings in 2020, efforts are being
promoted for more stable operation based on three principles, excluding the Units 1 to 3 reactor
buildings, where circulating water injection is ongoing, and the process building/high-temperatureincinerator storing contaminated water temporarily for purification treatment.
With regard to “removing” contamination sources, the third cesium adsorption apparatus(SARRY2) purifying high-concentration contaminated water has started full-scale operation since
July 2019, and a system using three units together with two established units (KURION andSARRY) has made possible stable purification treatment.
With regard to “not making water accessible” to a contamination source, the groundwater levelaround the reactor building is stably managed at a low level by multistory contaminated water
management, such as land-side impermeable walls and sub-drains, and the increase of thegeneration amount of contaminated water during rainfall also tends to be controlled by the site’ssurrounding pavement and the repair of broken parts of roofs. Through these measures, thegeneration amount of contaminated water has been reduced to about 180 m3/day (FY 2019) fromabout 540 m3/day (May 2014) before taking measures. The aim is to control the generation amountof contaminated water at about 150 m3/day in 2020 and below 100 m3/day in 2025.
With regard to “not leaking” contaminated water, since all water purified by the multi-nuclide
removal equipment, etc., has been stored in welded type tanks since FY 2019, leakage risk fromtanks is reduced. Treatment of the remaining water in the multi-nuclide removal equipment in thebottom of a flange type tank has been completed (July 2020), and only approx. 500 m3 of theconcentrated salt water remains in storage (as of the end of August, 2020). Also, efforts andmonitoring for the prevention of the spread of contamination are being carried out by the
maintenance of a sea-side impermeable wall, and monitoring of groundwater and the harbor.
As a result of the above efforts, treatment of the stagnant water in buildings excluding the Units
1 to 3 reactor buildings, the process building, and the high-temperature incinerator, is planned tobe completed in 2020. It is considered that contaminated water management has shifted to acertain level of stability compared with the situation requiring emergency measures immediately
after the accident.

34

In addition, for handling the water treated with the multi-nuclide removal equipment, so-called
ALPS, etc., a comprehensive examination, including technical aspects and the social impact suchas rumors was conducted by a national subcommittee, and a report was published in February
2020. Based on the report, the government has been arranging opportunities since April 2020 tohear the opinions of citizens at large and a wide range of relevant parties, including local
governments and agricultural, forestry, and fishery businesses, in order to determine the policy forhandling ALPS-treated water as the government.
ii.

Key issues and technical strategies to realize them

(1) Issues in the future treatment of stagnant water in buildings
According to the investigation since March 2019, a relatively high total α is detected at thebottom of the torus chamber of the reactor buildings of Units 2 and 3. In reducing the stagnant
water in the reactor buildings to about half of the level at the end of 2020 in FY 2022 to FY 2024, it
will be an important issue to prevent the spread of α-nuclides. As measures, it is required tostrengthen the monitoring of α-nuclides concentration in each building, and the water treatment
system and property analysis. Research and development are also required to establish theapproach to remove sludge precipitates containing α-nuclides.
Also, in the process building and the high-temperature incinerator, it became clear in December
2019 that there were zeolite sandbags with a high dose installed at the underground floor after theearthquake disaster. The maximum radiation dose rate on the surface of sandbags is as high as
approximately 3000 mSv/h in the process building and approximately 4000 mSv/h in the hightemperature incinerator. Therefore, in order to complete the treatment of the stagnant water inthese buildings in the future, dose mitigation measures will be an important issue. The remote
recovery method to extract and recover zeolite, etc., and store it in containers, etc., and the remoteaccumulation method to accumulate zeolite, etc., on the underground floor and temporarily store it
in containers, etc., are being examined. It is required to evaluate the radiation exposure dose
received during work, long-term safety, and the construction period, etc., comprehensively and toselect an appropriate method.
(2) Issues of contaminated water management considering the decommissioning process
such as fuel debris retrieval
In the fuel debris retrieval, it will be an important issue to examine the whole system ofcontaminated-water management based on various information, experience, and results obtainedin trial retrieval, gradual expansion of retrieval scale, and further expansion of retrieval scale. The
possibility that the material derived from fuel debris containing α-particles is mixed into the water
treatment system in association with cutting, fabrication, etc., of fuel debris cannot be denied. It is
required to take measures, such as the strengthening of monitoring of water treatment systems,
installation of α-particle collection systems, and criticality monitoring.
The expansion of the treatment capacity of the water treatment system and the systemconstruction to realize continuous stable operation will be an issue in the further expansion of
retrieval scale. Here, it is required to examine the miniaturization of equipment in consideration of
an installation location, the operation maintenance under a high dose, how to use the established35

purification equipment, etc., in addition to the removal system of α-particles and other radioactive
materials.
Also, it is required to ensure that a periodical inspection and update of equipment is carried out
in order to maintain the effect of contaminated water management over a long period. Furthermore,
as for the risk of large-scale natural disasters such as tsunamis and heavy rain, according to the“Review on Large Earthquake Model along the Japan Trench and Krill Trench (Summary Report)”
published by the Cabinet Office in April 2020, the impact was re-assessed for tsunamis and thetide embankment of Japan trench is scheduled to be newly installed by 2023. Going forward, themeasures should be taken in light of resilience (robustness) based on the re-assessment results.
While the current contaminated water management is shifting to a certain stable state, a long
period is required to complete fuel debris retrieval. It is important to see a medium-to-long period,
overlook the current contaminated water management anew, and examine the principles of morestable contaminated water management and more appropriate maintenance and management.
The summary of the technical issues and the future plans mentioned in this section is shown in
Fig. 7 and Fig. 10.
Fiscal year

2020

2021

2025

2022

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

Related milestones

2031

 To control the contaminated w ater generation amountto 100 m3/day or less(in 2025)

To reduce stagnant w ater 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

Stagnant water in buildings

Contaminated water
generation amount

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

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

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

Units 1 to 4 T/B, etc. Water level lowering
Confirmation of stagnant
Water level lowering for a 50% reduction
w ater characteristics
Simple measuresagainst α-nuclides

Units 1 to 3 R/B

To implement required measures in accordance with the stage of fueldebris retrieval

α-nuclides retrieval equipment: Design, manufacture, and installation

α-nuclides removal equipment: Operation

Alternative tank: Design, manufacture, and installation

Process building
High-temperatureincinerator

Zeolite dose mitigation measures/equipment: Conceptual examination, design,
manufacture, installation, and measures
Zeolite stabilization measures: Examination, design, manufacture, installation, and measures
Tide embankment
installation< Legend>

Building opening closure

Measures against natural
disasters

Sludge transfer equipment of decontamination equipment: Examination, design,
manufacture, installation, and transfer
Measures for VLFS

: The period of w ork:The period during w hich change is
expected

Examination, desig and construction for Tsunami disaster prevention ofJapan Trench

Measures against stagnant
water

Reversing valve pit
blockade

Underground water storage tank: Dismantling/retrieval and conceptual examination/design/retrieval

Fig.10 Key technical issues and future plans on contaminated water management (progress schedule)364) Fuel removal from spent fuel poolsi.

Targets and progress(Targets)(1) While the return of residents and reconstruction in the surrounding area is gradually advanced,
to carry out a risk assessment and ensuring safety certainly including preventing dispersion ofradioactive materials and to start the removal of fuel in SFPs (Spent Fuel Pools) in FY 2027 to
FY 2028 for Unit 1 and FY 2024 to FY 2026 for Unit 2. To complete the removal of fuel in SFPs
in FY 2020 for Unit 3.
(2) The fuel in Units 1 to 4 that were affected by the accident are taken out of 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 in the Common Spent Fuel Storage Pool is transferredand stored in the Dry Cask Temporary Custody Facility.
(3) To carry out the evaluation of long-term integrity and the examination for treatment for theremoved fuel and to decide the future treatment and storage method.
(Progress)
TEPCO is working on the new work plan indicated in the Mid-and-Long-term Roadmap and the
Mid-and-Long-term Decommissioning Action Plan.
In Unit 1, due to the hydrogen explosion, a roof stab, building materials, such as steel frames,
which constituted the upper part of the building, an overhead crane, etc., have collapsed as rubble
on the operating floor. While the residents were returning, from the viewpoint of further reductionof radioactive dust dispersion risk, the whole operating floor was covered with a large cover for theremoval of fuel in Unit 1 SFP. The removal method was changed to one in which rubble removal
and the removal of fuel in SFP are carried out under the cover. At present, the preparation to install
the large cover is advanced, and the operating floor work such as rubble removal is continuing. For
Unit 2, new method that the upper part of the operating floor will not be dismantled and accesses
from the south side of reactor building is adopted from the viewpoint of further reduction ofradioactive dust dispersion risk as well as Unit 1. Also, for dismantling the Units 1 and 2 common
exhaust gas stack, which was being carried out as part of the environmental improvement around
Units 1 and 2, a local company worked as a principal contractor, and the work was completed in
May 2020.
For Unit 3, fuel removal work is being advanced, considering safety the highest priority tocomplete the removal in FY 2020. As of August 2020, 315 fuel assemblies are removed, andtransfer to the Common Spent Fuel Storage Pool is being continued.
For Units 5 and 6, fuel will be appropriately stored in the SFPs of the units for the time being.
Then, the fuel will be removed in a range so as not to affect the work in Units 1 to 3. The securing
the available capacity of the Common Spent Fuel Storage Pool and the transfer of some fuel in the
Common Spent Fuel Storage Pool to the Dry Cask Temporary Custody Facility are required toremove all the fuel in SFPs, including Units 5 and 6, and store them in the Common Spent Fuel
Storage Pool. To achieve this, TEPCO is working on plans for expanding storage capacity in Dry

37

Cask Temporary Custody Facility and for off-site transportation of new fuel.
Efforts will be made to complete the removal of fuel in all units in 2031.
ii.

Key issues and technical strategies to realize them
For Units 1 and 2, it is required to advance the work steadily to realize the determined new

removal method.
(1) Fuel removal from SFPs
In promoting the project, it is essential to comprehensively consider concerning technicalcertainty, reasonability, rapidity, actual site applicability, project risk, etc., and a work schedule toresponse to issues after making all evaluations of safety in association with work and confirmingthat required sufficient safety is ensured.
For Unit 1, the design and installation of the large cover, and the removal of leftover objects
such as rubble on the operating floor will be promoted. There is an overhead crane in an unstablestate on the operating floor. Therefore, removing the overhead crane safely and steadily is one of
the main issues to prevent it from collapsing onto the fuel handling and falling into the spent fuelpool. Therefore, in the ongoing examination of how to remove the overhead crane, it is required toperform all safety assessments as an assumption, and it is important to carry out a comprehensive
examination based on the viewpoints of (i) formulating concrete work procedures and work plans
enabling the extraction of risk items, (ii) the risk scenario assumed from (i) and the measures, (iii)
extraction of points to consider such as the exposure of workers, etc., from an operator's
perspective, and (iv) reasonability and impact on other work.
Regarding the fuel assemblies in the cladding tube was damaged and stored before the accident,
specific handling plan needs to be considered.
In Unit 2, fuel in SFP will be removed from the opening on the south side of the outer wall on theoperating floor using a fuel handling machine composed by a boom-type crane-system, which has
not been used for nuclear facilities in Japan. Since it is a new system, the following is important: (i)to set up a design schedule with appropriate margins, (ii) to carry out a mockup test simulating thesituation in the field and an operation method fully reflecting the results on the design/manufacturingcertainly, and (iii) to be sufficiently familiar with the operation and functionality of systems
beforehand since removal is carried out by remote operation.
For Unit 3, removal of fuel in SFP, in which deformed handle was observed, is scheduled in thesecond half of FY 2020. It is also required to accumulate knowledge obtained, including
experiences at Unit 4, and to leverage it for the subsequent fuel removal from Units 1 and 2, as
well as to ensure the measures such as preparation for secure load of such fuel into transport cask
by lifting safely from fuel rack, improvement of quality assurance organization, and securing the
backup supply.
(2) Decision of future treatment and storage methods
The future treatment and storage methods for the fuel in pools need to be decided after
considering the impact of seawater and rubble exerted during the accident. The fuel removed from
Unit 4 has been evaluated to date and it is expected that the impact of seawater and rubble is small.
However, based on the situation of the fuel to be removed, it is required to advance the evaluation38

of long-term integrity and the examination for treatment and to decide the future treatment andstorage methods.
The main technical subjects and plans described in this section are summarized as shown in
Fig.11.
Fiscal year

2020 2021 2022

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

Milestones▽

Rubbleremoval, etc.

Unit 1

2025
Start Unit 2 fuel retmoval(FY 2024 to FY 2026)

2031
Complete fuel removal(in 2031)
Start Unit 1 fuel removal(FY 2027 to FY 2028)

Installation ofa 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.

FuelremovalUnit 2

Installation of a working platform on
Yardmaintenance/foundationthe south side and an opening/fuelhandling machine installation, etc.
improvement, etc.

<Legend>: Fuel retmoval w ork: The period during w hichchange is expected: Works other than fuelretmoval: The period during w hichchange is expected

Fuel removal

Unit 3
Units 5 and 6
Peripheral
environment

Common Spent
Fuel Storage Pool
cask

Fuel
removalUnit 6 fuelremovalSuspended while
work is performed

Dismantling of the upper partof Units 1/2 exhaust stack(completed in May 2020)

Suspended while
work is performed
at Units 1 and 2

Unit 5 fuel removal

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

Fig.11 Key technical issues and future plans for fuel removal from SFPs (Progress schedule)395) Utilization of Analysis Results for Smooth Promotion of Decommissioningi.

Significance and the current status of analysis
To safely and steadily proceed with decommissioning of the Fukushima Daiichi NPS, it isnecessary to establish and develop analysis facilities and functions required for handling of waste
or fuel debris. In addition, it is important to build a system to effectively utilize analyzed results foreach decommissioning operation.
TEPCO currently utilizes three facilities including the laboratory for Units 5 and 6, the chemical
analysis building, and the environmental management building, and performs analyses required forfacility administration and decommissioning progress, while planning to establish an analyticalfacility necessary for smooth performance of routine analyses related to processing/disposal ofwaste and fuel debris retrieval in the future.
The Radioactive Materials Analysis and Research Facility (Facilities Management Building,
Building 1, and Building 2) is being developed by JAEA under an official supplementary budget as
an essential analytical facility for decommissioning of the Fukushima Daiichi NPS. The analysis
results obtained are required to contribute to facilitation of smooth decommissioning, reliable
processing/disposal measures of radioactive material in decommissioning operation, andestablishment of technical foundation, etc.
ii.

Key issues and strategies
It is necessary to correctly recognize that the analysis results are “an important piece” to reduce

the range of uncertainties variously identified for the smooth decommissioning, and to establish
and improve the analysis system, as well as facilities and functions for analysis for enabling efficientcollection and assessment of analysis results. In particular, analytical data plays an important rolein the study on the retrieval method to mitigate excessive safety design while ensuring safety.
Therefore, analysis shall be positioned at a higher level in the decommissioning project.
Role sharing among the facilities that are currently planning to conduct analysis shall beappropriately optimized based on the characteristics of each facility, taking into account that thecontent, quality, quantities, etc., of the analysis required will change with the progress of
decommissioning. In doing so, the scalability of facilities and the flexibility of operations should beconsidered, taking into account a risk that the demand for analysis may increase.
In addition, due to the shortage of human resources required for stable operation of the abovementioned facilities, consideration should be given to securing and retaining of the analyticalengineers. In this respect, it is necessary to consider in advance the qualities expected for analyticalengineers in various analytical works that are required for optimization as mentioned above, andto develop a plan so that the required roles are appropriately achieved.
From the viewpoint of speeding up decommissioning, “immediacy” and “readiness” are requiredfor operating the facilities that do not need off-site transportation, such as radioactive material
analysis and research facilities. Although the analysis work for fuel debris retrieval is assumed tobe very difficult, especially when unknown samples are handled, an important stance is that thedecommissioning work shall be carried out on schedule by conducting analyses without delay. It is40

also important to pursue a reasonable analysis plan by comprehensively utilizing analysis results
and on-site information, such as by taking note of the fact that analysis results have functions tobenchmark the estimation results of internal conditions given by instrumentation monitoring, visualobservation, in-situ measurement, and evaluation of calculations (simulation).
Considering that the content, quality, quantities, etc., of the analysis required will change in theprocess of the decommissioning project (engineering of construction methods and equipment,
safety assessment and safety design, and decommissioning operations), TEPCO should establish
a system where TEPCO itself will actively commit control and leadership of the whole of activities
related to the analysis, by appropriately developing a role sharing of the organizations and facilities
in line with this consideration and make decisions based on comprehensive evaluation. From thisviewpoint, TEPCO is required, with the cooperation of outside experts, to start examining the overall
strategy and a plan for the analysis of decommissioning work as early as possible.

41

4 Efforts to facilitate research and development
1) Significance and the current status of research and development
There are many difficult technical issues requiring research and development to promote thedecommissioning of the Fukushima Daiichi NPS from the viewpoints of safety, certainty,
reasonability, rapidity, and field orientation. At present, when trial retrieval of fuel debris in 2021 isimminent, it is required to accelerate research and development under the consideration of theapplication to the site for a gradual expansion of retrieval scale and further expansion of retrieval
scale.
In order to solve these technical issues, basic fundamental research and application researchby universities in and outside of Japan and research institutions such as the JAEA and practicalapplication research and field demonstrations by International Research Institute of Nuclear
Decommissioning (hereinafter referred to as "IRID”), overseas enterprises and TEPCO, etc., arebeing performed by various entities of industry/academia/government. In order to promote theresearch and development, the government is supporting highly-difficult ones among appliedresearch, practical application research and field verification by the Government-led R&D Programon Decommissioning and Contaminated Water Management, and ones regarding basic andfundamental research by the World Intelligence Project for Nuclear S&T and Human Resource
Development (hereinafter referred to as "World Intelligence Project"). TEPCO is also working on
the research and development directly linked with actual site applicability. The outline of theresearch and development organization i s shown in Fig.12.
NDF established a “Decommissioning R&D Partnership Council,” which examines the issues,
such as the information sharing of R&D needs and seeds, the arrangement of research anddevelopment based on the needs of decommissioning work, and the promotion of cooperation forresearch and development and human resources development, with the related organizations as
members.
Also, in promoting research and development, it is important to make use of the Naraha Remote
Technology Development Center, the Okuma Analysis and Research Center, and Collaborative
Laboratories for Advanced Decommissioning Science (hereinafter referred to as “JAEA/CLADS”)
and arrange the decommissioning R&D base, including international viewpoints.

42

Ministry of Economy, Trade,and Industry

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

Government-led Project ofDecommissioning andContaminated Water
Management

Support*8

Operating costsubsidy

Assistance

JAEA

NDF

Fund establishment corporation

Technical committees for decommissioning, etc.

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

Participation

Secretariat

Subsidized company
Othermakers, etc.
(including
overseascompanies)

International Res earchInstitute for Nuclear
Decommissioning

Joint application, etc.

Project
implementation

National Research and
Dev elopment Agency
Plants, manuf acturers, etc.
Electric power companies,
etc.

Sharing and planning oftechnical development
information

Cooperative relation

Foreigngovernmentorganization

Naraha Remote Technology
Dev elopment Center

Cooperative relation

Decommissioning R&D
Partnership Council

Assignment*7
Assistance

Fukushima research anddevelopment department

Fund for Countermeasures for Decommissioning
and Contaminated Water Treatment

AssistanceWorld Intelligence Project for Nuclear
S&T and Human Resource
Development

Support*9

Okuma Analysis andResearch Center

Administrative
instructions

CLADS

*6
Examination request
and support

Consignment
and joint
research

Exchange of research needs
and seeds
Bridge-building for results

TEPCO
Holdings

Participation

Cooperation
Consignment

Project
implementation

A company
making a contract

Project Management
Operation

Basic research for decommissioning
Platform

Secretariat

Universities,
research
institutions,etc., in
Japan

Joint
research

Overseas
universities
and research
institutions

Companies in Japan andoverseas companies*1 The Decommissioning R&D Partnership Council is established in the NDF based on the determination by Team for Countermeasures for Decommissioning and Contaminated Water Treatment.
*2 The arrow draw n in a thick solid line indicates expenditures such as research expenses and operating expenses (excluding facilities expenses), the arrow draw n in a thin solid line indicates a cooperative relation, etc., and the arrow draw n in adotted line indicates the participation in the Decommissionin g R&D Partnership Council.
*3 Some organizations such as JAEA are located at tw o or more places.
*4 Each organization has cooperative relations w ith foreign organizations based on MOU, etc., respectively.
*5 Research and development uniquely conducted by the Central Research Institute of Electric Pow er Industry, etc., are omitted in this f igure.
*6 Although among the World Intelligence Project for Nuclear S&T and Human Resource Development the part adopted up to FY 2017 is the consignment f rom the Ministry of Education, Culture, Sports, Science, and Technology to a company
making a contract, it is omitted in this f igure.
*7 Although the subsidy for the World Intelligence Project for Nuclear S&T and Human Resource Development is delivered to JAEA, it is expressed as w hat is delivered to CLADS, to make it easier to understand.
*8 With regard to the Government-led Project of Decommission ing and Contaminated Water Management, based on the policy in the Mid-and-Long-term Roadmap or Strategic Plan and the progress situation of research and development, the NDF
f ormulates a draf t plan of the next research and development, and the Ministry of Economy, Trade, and Industry determines it.
*9 The NDF participates as a member in a steering committee of the World Intelligence Project for Nuclear S&T and Human Resource Development.

Fig.12 Overview of the R&D structure of the decommissioning of Fukushima Daiichi NPS(As of FY 2020) (Red: Areas with strengthened systems)

2) Key issues and strategiesi.

Strengthening the research and development management organization in the
Government-led R&D Program on Decommissioning and Contaminated Water
Management
Although TEPCO focused on the research and development for immediate decommissioning

work, it has been transferring to strategic efforts based on the mid-and-long-term plan in researchand development, such as publishing the Mid-and-Long-term Decommissioning Action Plan. Basedon this situation, for the Government-led R&D Program on Decommissioning and Contaminated
Water Management, it is required to strengthen the research and development under theconsideration of needs and actual site applicability by TEPCO. Therefore, it was decided that NDF
and TEPCO should be further involved in the Government-led R&D Program on Decommissioning
and Contaminated Water Management in the future.
Specifically, in the Government-led R&D Program on Decommissioning and Contaminated
Water Management, the organization resulted in one in which NDF participated in the secretariatof the Government-led R&D Program on Decommissioning and Contaminated Water Management
and clarified the involvement of TEPCO as an actual site applying party, with the recognition ofissues that the functions of both planning and status control of a project should be strengthened.
TEPCO reflects requirements from the viewpoint of actual site applicability by jointly applying for
subsidy with R&D implementation entities, and carries out status control cooperating with project
management.
TEPCO is required to construct such a scheme and strive to focus on research and development
43

it performs. While strengthening communication by means of information exchange and dialogues
with TEPCO, NDF will plan matters considering needs in the field and actual site applicability andmanage status control of research and development to achieve research and development
conforming to the purpose of research and development and the target period for achieving results.
ii.

Formulating the R&D medium-to-long-term plan foreseeing about ten years for the time
being
The Mid-and-Long-term Roadmap indicated the course of action for about ten years for the time

being and the promotion of research and development to support it. With regard to this matter,based on the Mid-and-Long-term Decommissioning Action Plan, NDF and TEPCO decided toformulate the R&D medium-to-long-term plan overlooking the overall research and development
for about ten years for the time being in order to appropriately manage the extraction and executionof the required research and development for achieving the further expansion of fuel debris retrieval
scale. In the R&D medium-to-long-term plan, the items and content of research and development
assumed at present in each stage of fuel debris retrieval are identified in a manner linked with the
TEPCO’s Mid-and-Long-term Decommissioning Action Plan. Also, formulated based on this R&D
medium-to-long-term plan, the next R&D plan formulated every fiscal year will clarify how andwhere each research and development project corresponds to the decommissioning process. The
R&D medium-to-long-term plan will be updated and expanded continuously based on theinformation made clear by the progress of Internal investigations of PCV, etc., and fuel debris
analysis, the progress of research and development, the revision of the TEPCO’s Mid-and-Longterm Decommissioning Action Plan, etc.
iii. Matching of needs and seeds of decommissioning work site and universities/research
institutions
Universities/research institutions bearing basic infrastructure research are expected to maintainand develop human resources and knowledge/infrastructure to make a quick response whentechnical issues requiring scientific knowledge occur. It is important that universities/research
institutions deeply share recognition of issues in the field of decommissioning.
Some basic fundamental research contributing to problem-solving in the field of
decommissioning have obtained outstanding research results mainly in the World Intelligence
Project of the Ministry of Education, Culture, Sports, Science, and Technology and JAEA/CLADS.,
It is an important issue to reflect the results in the field of decommissioning directly. In order toachieve this, it is essential to match the needs of the decommissioning site with the seeds ofuniversities and research institutions, build bridges for excellent results obtained, while making useof the overall map of the basic foundation research by JAEA/CLAD. Under the circumstances, joint
research with universities was newly started in TEPCO from FY 2019 to find the technical seeds
for decommissioning owned by universities based on the result of the World Intelligence Project.
The related organizations, such as the government (the Ministry of Education, Culture, Sports,
Science, and Technology, the Ministry of Economy, Trade, and Industry), JAEA/CLADS, NDF, andTEPCO, need to strengthen cooperation towards further matching of the needs and seeds andbridging for the results.

44

5 Activities to support our technical strategies
1) Further strengthening of project management and improvement of capability
required as a decommissioning executori.

Significance and the current status of project management(1) Formulating the Mid-and-Long-term Decommissioning Action Plan
Since the accident at the Fukushima Daiichi NPS, TEPCO has conducted decommissioning
project in accordance with the requests based on the Act on Special Measures Concerning Nuclear
Emergency Preparedness and the Nuclear Reactor Regulation Law6 and the target process of the
Mid-and-Long-term Roadmap determined in the Inter-Ministerial Council for Contaminated Water
andDecommissioning

Issues.

Byformulating

andpublishingtheMid-and-Long-term

Decommissioning Action Plan showing the processes for how to achieve such targets, in light of
the ten years that have passed since the accident, TEPCO made transparent the decommissioning
project to local areas and society, made clear its attitude toward tackling decommissioning
independently, and materialized the complicated work prospect over a long period.
The decommissioning work for the Fukushima Daiichi NPS is a project with significant
uncertainty. However, since the plan under the consideration of the medium and long term can beformulated for research and development, human resources, and procurement by thinking of the
Mid-and-Long-term Decommissioning Action Plan, the meaning of formulating the Mid-and-Longterm Decommissioning Action Plan is significant. It is also important to carry out constant review
based on new knowledge, the on-site situation, etc., for utilizing the Mid-and-Long-term
Decommissioning Action Plan effectively in the future.
(2) Further strengthening of project management
In April 2020, TEPCO changed its decommissioning project to project management-based
structure by reorganizing Fukushima Daiichi D&D Engineering Company. However, TEPCO hasjust stood at the starting point as project management-based organization and the priority is tooperate project management structure.
To implement complex, multilayered and large-scale decommissioning project such like fueldebris retrieval in a safe and steady manner over a long period of time, appropriate and efficient
operation should be performed while further strengthening project management structure byaccelerating improvement of functions to manage project risks as well as managing engineeringand R&D in an integrated manner.
ii.

Key issues and strategies(1) Reinforcement of “safety and operator's perspectives” in project activities
When promoting efforts such as design examination (engineering) for construction method andequipment, there is a tendency to focus on realizing a construction method, equipment, etc.,
physically, especially for issues with severe technical difficulty. However, in order to realize theresults of efforts in the field, it is indispensable to fully reflect the following in the construction
method and equipment in addition to a physical realization:
6

The Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material, and Reactors

45

“The safety perspective” as a project executor7 handling dangerous substances ofnuclear fuel material, etc.

“The operator’s perspective”8 familiar with the field of the Fukushima Daiichi nuclear
power plant decommissioning

Therefore, these perspectives need to be fully reflected in the project activities until aconstruction method and equipment are realized in the field. Without sufficient feedback, the resultsof the construction method and equipment that are unsuitable to the site will be brought about, andsafe and stable decommissioning will be disturbed.
To avoid such a situation, a business process to incorporate a “safety perspective” and an“operator's perspective” in the upstream of project activities needs to be established at an earlystage.
(2) Improving the owner's engineering capability
For operations with limited information (accompanied with significant uncertainty) and which are
unprecedented and highly challenging, such as fuel debris retrieval, a conventional engineering
approach9 is not always applicable. Rather, target-setting and the specifications required by theoperation executor (TEPCO) will not necessarily be clear at the time of initiating the engineering
process. Consequently, the establishment of performance requirements, the physical feasibility ofengineering methods and equipment, and the extent of performance assurance coverage have to
be of a trial-and-error-nature. Therefore, the operation executor’s performance requirements, theestablishment of the supply chain’s functions and its engineering process have to be based on
iteration10 to some extent.
For iteration-type engineering, the contract between a project executor and a supply chain is notconventional 11 . Therefore, it is strongly required that TEPCO, as a project executor, “make a
judgment on engineering and is responsible for the results.” Therefore, it is required to improve theengineering capability (owner's engineering capability) carried out independently by TEPCO, aproject executor as an owner 12 , such as the project management capability, the capability to
optimize the whole supply chain that should be owned as a project executor, specifically, theAlthough the fuel debris is in a certain safe state now, the fuel debris retrieval work will cause
disturbances to this stable state. Namely, since α-radioactive material is handled in an unsealed
state in fuel debris retrieval work and a criticality risk may be increased temporarily, more elaborate
work management than before (criticality control, radiation protection, operation management,
monitoring strengthening, etc.) is required.
8
An operator is a collective term for the people and organizations handling the site (operation,
maintenance, radiation control, instrumentation, analysis, etc.)
9
A supply chain advances engineering based on requirement specifications provided by TEPCO, asa project executor.
10 A method of gradually increasing the completeness of engineering by finding the next result basedon a certain result and repeating this cycle.
11 In the conventional construction of nuclear power stations, a supply chain has delivered completed
products to a project executor after guaranteeing the performance (Full turnkey contract).
12 An owner here has three positions of a party responsible for disaster occurrence, a specified
nuclear facility licensee, and a facility owner. TEPCO is executing the decommissioning projectfrom these three positions. (A project executor of decommissioning)
7

46

capability to make an engineering judgment, the capability to evaluate business risk, the capability
to materialize order specifications.
With that in mind, in deciding retrieval methods and equipment, it is important that methods andequipment to be adopted in the end will be decided in accordance with ALARP13 based on safety,
through the cycle of “define the safety standards (safety perspective)”, “indicate the feasibility onsite (operators’ perspective)”, and “examine and discuss at project (project management)”.
(3) Developing and securing human resources
Human

resourcesdevelopment

isindispensableasinfrastructuretoimplement

decommissioning project over a long period smoothly. It is important for TEPCO to assume
occupational categories and the number of engineers to be required in the future (design, operation,
maintenance, chemical analysis, safety assessment, radiation control, etc.) and the time to berequired in light of the Mid-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 staff securing systematically. In addition, as it is essential to train and secure
future researchers and engineers, it is important for industrial-academic-governmental institutions
relating to nuclear power, as a whole, to steadily promote these efforts. Therefore, it is necessary
to further promote and strengthen measures for securing human resources who will lead the next
generation, such as children in elementary and secondary education stage, students in the higher
education stage including universities or colleges of technology, young researchers and engineers,etc.

2) Strengthening international cooperationi.

Significance and the current status of international cooperation
In recent years, nuclear reactors and nuclear fuel cycle facilities, constructed in the dawn ofnuclear power, are coming to the end of operating life and these decommissioning have alreadybeen progressing in the world. At the nuclear reactors experienced severe accidents, stabilizationand safety measures have been taken in these facilities for a long time. In addition, for pastoverseas nuclear-related sites (legacy sites), it is expected that there was significant uncertainty inthe management of a variety of radioactive substances and it would take a long period fordecommissioning and environmental remediation. Despite facing technical difficulty called“unknown unknowns” (things we don’t know we don’t know), and issues such as longtime project
management and securing a large amount of money, each country continues the challenge forovercoming them.
In order to steadily advance decommissioning of the Fukushima Daiichi NPS handlingengineering issues with a high level of difficulty, it is important as a risk reduction strategy to learn
lessons from examples such as precedent decommissioning activities and utilize them indecommissioning. Also, to maintain and develop continuous understanding/concern andcooperative relations with international society over decommissioning, it is important to return theknowledge, etc., which was obtained through the accident and decommissioning of the Fukushima
Daiichi NPS to international society positively and strategically and to promote reciprocal
13

It means that radiological impacts must be reduced as far as reasonably practicable.

47decommissioning open to international society through information dissemination to internationalsociety and participation in the international joint activities.
In regards to the international cooperation, it is important to utilize a multilateral cooperation
framework through IAEA, Organization for Economic Co-operation and Development/Nuclear
Energy Agency (hereinafter referred to as “OECD/NEA”), etc., in addition to proceed with bilateral
cooperation in harmony with the circumstance in each country. These international institutions havean important role including designing the international standard for decommissioning. Participatingin the discussion for developing the international standard based on the experience of
decommissioning in Japan, it is important for proceeding with the decommissioning of the
Fukushima Daiichi NPS in an open manner on the international basis. It leads to share ourexperience with each country, it is also expected to fulfill the Japan’s responsibility to theinternational society. From this perspective, NDF, based on these, currently focuses on information
dissemination on the decommissioning through taking part in side events of IAEA General Meetingand giving speeches at key international meetings including OECD/NEA Steering Committee.
ii.

Key issues and strategies
We will soon mark ten years since the accident. From the viewpoint of concentrating the wisdomin the world for the decommissioning of the Fukushima Daiichi NPS, since a recipient's concerns,
etc., may change a little from the time of the accident, it is important to provide informationconsidering this point even if it is the same information. Specifically, in addition to providing detailed
exact information for experts, it is also necessary to provide intelligible information for non-experts
or devise appropriately considering recipients' intelligibility concerning the circumstances of theaccident.
While the engineering of the Fukushima Daiichi NPS is put into practice, it is important to always
keep up the latest situation of world's superior technologies and human resources and effectively
exploit them. Therefore, it is necessary to understand the latest global information, including eventhe private sector situation, make efforts for continuous communication with these private
enterprises, and form an environment in which required technology is accessible when required
while sharing information on the progress of decommissioning work.

3) Local community engagementi.

Significance and the current status of local community engagement
While the residents are returning and reconstruction is progressing gradually in the surroundingarea, the confidence from the communities is indispensable to advance decommissioning safely
and steadily. Therefore, it is important to listen to uneasiness and questions of the local residents
sincerely and make efforts to have them understand and feel ease about the decommissioning
work through bidirectional communication of delivering exact information intelligibly and quickly. In
addition, to accomplish the long-term decommissioning, it is essential to have continuous
cooperation from local businesses and other companies. At the same time, participation of local
businesses in the decommissioning project is a crucial pillar for TEPCO to contribute to thereconstruction of Fukushima, because it will revitalize the decommissioning related industry, create
jobs and technologies in this area, and spread the results to other regions and industries.

48

Under the fundamental principle of “coexistence of reconstruction and decommissioning”,
TEPCO will also cooperate with efforts to realize the “Fukushima Innovation Coast Framework”
holding up decommissioning related industry accumulation to the Hamadori region as priority areas
and accomplish decommissioning while coexisting with the region.
Last fiscal year, while obtaining the Fukushima Innovation Coast Framework Promotion
Organization's cooperation, TEPCO held a decommissioning project matching event for local
businesses. Also, at the end of March 2020, it formulated the “commitment to Fukushima residents
for the coexistence of reconstruction and decommissioning” (hereinafter referred to as"Commitment") summarizing the efforts, such as the participation of local businesses indecommissioning project, the attraction of companies outside the area, support for local companies
toward human resources development and cooperation with universities, etc. It re-expressed thedetermination to fully address decommissioning project as a member of the community.
To undertake the efforts of the “Commitment,” TEPCO has set up a joint consultation counter
for local companies who are interested in participating in the decommissioning project incooperation with the Fukushima Innovation Coast Framework Promotion Organization and the
Fukushima So-So (Soma and Futaba regions) Reconstruction Promotion Agency, and is preparing
to hold business fairs between the prime contractor and local companies. To provide support tohelp local companies participate in the projects, TEPCO subdivided the medium-to-long-term
outlook in the decommissioning project as well as the detail, timing and scale of the project orders
to be placed as much as possible, and formulated “Medium-to-long-term outlook in thedecommissioning” that specifically states equipment or technology required for each project in
September 2020. Now, TEPCO is explaining the outlook to the prime contractor and the local
governments and association of commerce and industry.
ii.

Key issues and strategies
Misunderstanding, concern, and rumors are caused by inappropriate information transmission

about decommissioning, which ruins appreciation and confidence in the decommissioning projectof the regions and the whole society and leads to the delay of decommissioning. Therefore, TEPCO
needs to utilize various tools, such as informational magazines, WEB sites, and motion videos, inaddition to the visit of the Fukushima Daiichi NPS and the decommissioning museum (Tomiokacho), and inform as to the present situation and progress status of decommissioning intelligibly andquickly.
Also, the government, NDF, and the TEPCO, under suitable cooperation, need to provide
information more carefully and make efforts to build confidence with regions. Therefore, we needto positively arrange an opportunity to communicate directly with the people in regions. We alsoneed to make efforts for bidirectional communication by dialog, such as listening to uneasiness andquestions of the participants sincerely through the events of the International Forum on theDecommissioning of the Fukushima Daiichi NPS, etc., held by NDF, and deliver exact information
intelligibly and quickly.
TEPCO must not end this “Commitment” just as a shape, but secure effectiveness. Therefore,
the specialized department working on community symbiosis plays a key role to update and add
the detail of “Medium-to-long-term outlook in the decommissioning project” as required with the49progress of the decommissioning project. In addition, they will positively provide coordination withthe local communities by carefully explaining it continuously via the local governments or the
association of commerce and industry through dedicated joint consultation centers and business
fairs targeting local companies. TEPCO itself is providing support to local companies to enhancetheir technical capabilities, while inviting companies from outside the region to do business withthem. In addition, TEPCO establishes a system where the local companies are encouraged to offer
technical guidance to the primary contractors and, if certain results are achieved, incentives are to
be given. Efforts are being made to build a foundation for the local economy and foster local
businesses and human resources through the decommissioning project. Furthermore, not only the
research and development on decommissioning, but as companies outside the region expand theirbusinesses in the area and technical support to local companies progresses, it is expected that the
number of engineers and researchers visiting and staying from outside the region will increase. It
is required to develop the necessary environment and support so that such external humanresources can fit into the regional society and play an active role as a member of the local
community.
For carrying out the work of community symbioses, it is also required to strengthen organizations
if needed since close cooperation is required between each department. In addition, NDF needs tocontinue and strengthen cooperation and collaboration with local governments, including
Fukushima prefecture, the Fukushima Innovation Coast Framework Promotion Organization, andthe Fukushima So-So (Soma and Futaba regions) Reconstruction Promotion Agency, etc.

50