Technical Strategic Plan 2019
For Decommissioning of the Fukushima Daiichi
Nuclear Power Station ofTokyo Electric Power Company Holdings, Inc.

Overview

September 9, 2019

Nuclear Damage Compensation andDecommissioning Facilitation Corporation
NDF

Table of contents
1

Introduction ............................................................................................................................... 1
1)

Structure and system toward the decommissioning of the Fukushima Daiichi Nuclear
Power Station .................................................................................................................... 1

2)
2

Strategic Plan..................................................................................................................... 3
Decommissioning of the Fukushima Daiichi NPS as risk reduction strategies ........................ 4

1)

Basic concept of the decommissioning of the Fukushima Daiichi NPS ............................ 4

2)

Progress status of the decommissioning of the Fukushima Daiichi NPS ......................... 4

3)

Basic concept of reducing risk of radioactive materials .................................................... 6

3

Technological strategies toward decommissioning of the Fukushima Daiichi NPS ............... 12
1)

Fuel debris retrieval ......................................................................................................... 12

2)

Waste management ......................................................................................................... 33

3)

Contaminated water management .................................................................................. 39

4)

Fuel removal from spent fuel pools ................................................................................. 42

5)

Other specific measures .................................................................................................. 46

6)

Comprehensive efforts for the decommissioning project of the Fukushima Daiichi
NPS.................................................................................................................................. 50

4

Handling critical enablers for smooth operation of the project ............................................... 52
1)

Actions toward improvement of working environment and conditions ............................ 52

2)

Enforced management structure for steady mid-and-long-term decommissioning ........ 52

3)

Developing and securing human resources .................................................................... 52

5

R&D Initiatives ........................................................................................................................ 54
1)

Basic policy for R&D ........................................................................................................ 54

2)

R&D of decommissioning required for on-site work/engineering .................................... 55

3)

Enhancement of basic study and R&D infrastructure for the success of thedecommissioning project ................................................................................................. 56

6

Enhancement of international cooperation ............................................................................. 58
1)

Significance of international cooperation ......................................................................... 58

2)

Facilitation of international cooperation activities ............................................................ 59

3)

Close cooperation with relevant domestic organizations ................................................ 60

7

Local community engagement ................................................................................................ 61
1)

Approaches for local community engagement ................................................................ 61

2)

Actual effort for better communication ............................................................................. 61

3)

Measures to reputational damages ................................................................................. 61

4)

Decommissioning that moves forward together with the recovery of the community ..... 61

1 Introduction
Eight years have passed since the accident at the Fukushima Daiichi Nuclear Power Station.
There has been a certain outlook for the short-term response, as progress has been made at theaccident site in managing contaminated water including the construction of the land-side
impermeable wall and in removing fuel from the spent fuel pools as well as improving work
environment at the site. Going forward, long-term approach like fuel debris retrieval is needed andmid-and-long-term responses are required. When addressing more complex, uncertain challenges
over the long term, more systematic approach from mid-and-long-term perspective will be needed
to solve the challenges rather than fulfilling tasks by resolving imminent issues one by one. Under
the circumstances, as engineering toward fuel debris retrieval is well under way, the phase of
decommissioning moves to response for mid-and-long-term vision. With that in mind, in the“Technical Strategic Plan 2019 for Decommissioning of the Fukushima Daiichi Nuclear Power
Station of Tokyo Electric Power Company Holdings, Inc.”, the direction from a mid-and-long-term
perspective in overlooking total approach for decommissioning of the Fukushima Daiichi NPS ispresented including waste management, as well as the strategical recommendation to determine
methods of fuel debris retrieval for the first implementing unit in accordance with the milestone set
in the Government-developed “Mid-and-Long-Term Roadmap towards the Decommissioning of
TEPCO’s Fukushima Daiichi Nuclear Power Station” (hereinafter referred to as the “Mid-and-Longterm Roadmap”) that was revised in September 2017.

1) Structure and system toward the decommissioning of the Fukushima Daiichi
Nuclear Power Station
Tokyo Electric Power Company Holdings, Inc. (hereinafter referred to as “TEPCO”) is reinforcing
its project management structure with the goal of implementing the ongoing activities reliably while
responding to mid- and long-term issues in a strategic manner to make steady progress of
decommissioning operation. In addition, to ensure the implementation of the decommissioning
financially, a law to partially revise the Nuclear Damage Compensation Facilitation Corporation Act
was established in May 2017 and came into effect in October of the same year. Under this revised
Act, Nuclear Damage Compensation and Decommissioning Facilitation Corporation (hereinafterreferred to as “NDF”) has been assigned the new duty of managing the reserve fund fordecommissioning. 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 competent minister (the Ministerof 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 prepared jointly by
NDF and TEPCO and approved by the competent minister (Fig. 1).

1

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

Nuclear Regulation Authority(Chairperson: Chief Cabinet Secretary) Approval of implementation
plan, pre-service inspection,
welding inspection, etc.

Mid-and-Long-Term Roadmap

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

Progressmanagement

Granting of
project budget

R&D organization

Apply forapproval

Approve

Nuclear Damage Compensation and Decommissioning Facilitation Corporation

 Development of a mid-to-long-term strategy
Withdrawal plan Tech. support for progress mgmt of important issues(in collaboration)
 R&D planning and progress management
Strategic  Strengthen international partnershipReserve Fund forplan  Management of Reserve Fund for
Decommissioning
Decommissioning

International Research Institute for
Nuclear Decommissioning (IRID)*
Share progress
Japan Atomic Energy Agency (JAEA), and challengesetc.
 R&D implementation
ReportAdvice, guidance, recommendations,supervision and support
Reserverelated to project management, etc.

Monitoring, examination

ReportReport 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 spent fuel pools, fuel debris retrieval, waste disposal,
improvement of power plant premises and working environment, management of Units 5 and 6, etc.
 Through TEPCO's management reform, the funds required for decommissioning should be reserved
responsibly (Implementation of new comprehensive special project plan)

Implementation
plan* TEPCO, a decommissioning project operator, participates as a member of IRID and shares the needs, challenges, and results of research and development.

Fig.1 Division of roles of related organizations in decommissioning of the Fukushima Daiichi NPS
In this decommissioning reserve fund system, NDF plays even greater roles and responsibilities
than before as the major supervisor and administrator of the decommissioning project conductedby TEPCO. These include (1) appropriate management of the funds for decommissioning, (2)maintenance of an appropriate system for executing the decommissioning, and (3) steady work
management based on the decommissioning reserve fund system. Specifically, 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” (“The Policy
for Preparation of Withdrawal Plan”) that was developed based on the “Technical Strategic Plan for
Decommissioning of the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power
Company Holdings, Inc.” (hereinafter referred to as the “Strategic Plan”). NDF also support theappropriate and steady implementation of the decommissioning through activities such as
assessing the adequacy of TEPCO’s efforts in the course of jointly preparing the Withdrawal Planin terms of project execution (including the aspect of collaboration and communication with local
communities) (Fig. 2).

2

Government*) Continually revise based on the progress of programs

Mid-and-Long-Term Roadmap*)

Next R&D Plan

(Project of Decommissioning andContaminated water management)

Proposals for Revise

Strategic Plan (annual)

NDF

The Policy for Preparation ofWithdrawal Plan for Reserve Fundfor Decommissioning (annual)

Withdrawal Plan for Reserve Fundfor Decommissioning (annual)

Feedback

TEPCO

Jointly created with NDF and approved by METI
• Contaminated water management PG• Pooled fuel retrieval PG• Fuel debris retrieval PG• Waste management PG• Site area /Work environment improvements PG• Management of Unit 5 and 6 PG
• Non-program work/Operational management

On-site work
Engineering

Planning from
Mid-and-long-term aspect

Feedback

Technological
Development

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

2) Strategic Plan
NDF has issued the Strategic Plan every year since 2015 with the goal of providing reliable
technological grounds for the government’s Mid-and-Long-term Roadmap and contributing to its
smooth and steady implementation and update. Since the Strategic Plan 2018 and future editions,
it includes not only the issues focused on fuel debris retrieval and waste management but alsomeasures against contaminated water and fuel removal from spent fuel pools by extending thestudy range.
As stated earlier, the Strategic Plan 2019 presents a mid-and-long-term direction that oversees
the entire efforts of Fukushima Daiichi NPS including waste management, while providing thestrategic recommendations to determine methods of fuel debris retrieval for the first implementing
unit.

3

2 Decommissioning of the Fukushima Daiichi NPS as risk reduction
strategies
1) Basic concept of the decommissioning of the Fukushima Daiichi NPS
Concerning to the Fukushima Daiichi NPS decommissioning, the basic concept is to continuously
and quickly reduce the radioactive risk caused by the accident that does not exist in the usual NPS.

2) Progress status of the decommissioning of the Fukushima Daiichi NPS
The Fukushima Daiichi NPS has the necessary safety measures in place that are required by
the NRA in “the matters for which measures should be taken” and is maintained in a state with acertain level of stability. In addition, as a result of various risk reduction measures taken so far, risk
reduction has been continuously achieved as follows:(1) Contaminated water management
Measures have been taken based on the three principles on the issue of contaminated water(“Removing” contamination sources, “Redirecting” fresh water from contamination sources, and“Retaining” contaminated water from leakage).
As a measure of “Removing” contamination source, radioactive materials are removed fromcontaminated water with multi-nuclide removal equipment. As measures of “Redirecting” fresh
water from contaminated sources, freezing operation of the land-side impermeable walls has
been completed in all the areas by September 2018. Along with the reinforcing the sub-drain
system, total amount of the contaminated water is decreasing as a result of reduced inflow into
the buildings and sharp decrease in the amount of the water transferred from the groundwaterdrains to the buildings. As measures of “Retaining” contaminated water from leakage, thestrontium treated water stored in flange tanks has been purified with multi-nuclide removal
equipment and transferred to more reliable welded tanks in November 2018. In addition,transferring of treated water stored in flange tanks to welded tanks has been completed in March
2019, resulting in a drastic reduction of the risk of leakage from flange tanks.
In treating stagnant water in the buildings, the amount of stored water has been decreasing
steadily by lowering the water level in turbine buildings with the goal1 of completing the treatment
in 2020. At the present time, the lowest floor level of turbine building in the Unit 1, and the lowest
floor’s intermediate ceiling of turbine buildings in the Units 2 to 4 became visible. In addition,
separation of the penetration between Units 1 and 2 completed in 2018 (one between Units 3
and 4 has completed in 2017). On the other hand, regard to the target decrease of the radioactive
materials in the stagnant water in the buildings up to one tenth of the amount at the end of FY
2014 in FY 2018, the evaluation became difficult because high radioactive concentrations weredetected in some areas with the progress in the treatment of stagnant water, though treating ofExposing the floor line for buildings other than the reactor buildings and lowering the water level ofthe reactor building to T.P.-1740mm (O.P. - 300 mm) or less. (Cyclic water injection cooling is carriedout in the reactor building, and stagnant water continues to exist).
1

4

radioactive materials has been conducted more than scheduled. Thus, ongoing efforts will bemade to complete the treatment of stagnant water in the buildings in FY2020.
Moreover, as for the water treated by the multi-nuclide removal equipment, comprehensive
discussion including social aspects such as mitigation of reputational damages have been madein the Government-led subcommittee on the Water Treated by the Multi-nuclide Removal
Equipment2.
(2) Fuel removal from spent fuel pools
In Unit 1, to remove fuel from SFP, rubble removal in the operating floor continues which has
started in 2018.
In Unit 2, contamination in the operating floor was investigated from November 2018 to
February 2019. Based on this investigation, process among other things has been studied forfurther fuel removal from SFP. In addition, the exhaust stuck for Units 1/2, in which somefractures were found at the support structure due to the impact of the earthquake, will bedismantled at the upper part in order to secure seismic safety margin and not to affect the removal
operation of fuel n SFP.
In Unit 3, the fuel removal has started in April 2019 though it was behind the original schedule
because of some troubles on fuel handling equipment occurred during the trial operations.
(3) Fuel debris retrieval
In Unit 1, internal investigation of Primary Containment Vessel (hereinafter referred to as the“PCV”) will be conducted in FY2019 by using a boat-shaped submersible apparatus that was
newly developed for access investigation, since the deposits that was identified by theinvestigation internal PCV in 2017 was located under the water. In this investigation, a small
amount of deposit is to be sampled.
In Unit 2, as a result of the deposit contact investigation inside PCV by using a remote device
in February 2019, it was observed that some pebble sized deposits can be moved at the bottomof the pedestal in PCV and the platform. In addition, grasping distribution of structures anddeposits inside the pedestal and a small quantity of sampling is scheduled.in the future.
In Unit 3, study to lower the water level has been made since the water level inside PCV ishigh, being 6 meters. At first, quality of the water is to be examined.
(4) Waste management
For high radiation dose rubbles generated from Units 1 and 2, operation of solid waste storage
building No.9 has started in February 2018. As for secondary waste generated by purification ofcontaminated water, it is currently being stored in temporary storage, and operation of large

Subcommittee on the water treated by the multi-nuclide removal equipment
https://www.meti.go.jp/earthquake/nuclear/osensuitaisaku.html#task_force425waste storage will start to store these waste after this. Storage management plan was revised inJune 2019 based on the revised results of predicted generation of solid waste.

3) Basic concept of reducing risk of 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 Nuclear Decommissioning Authority (hereinafterreferred to as “NDA”) is used to express the magnitude of risk (risk level) of 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 radioactive substance into the human
body, and “Safety Management” which is used as an index to indicate the likelihood of occurrenceof the event.
ii.

Identification of risk source and risk assessment
The major risk sources of the Fukushima Daiichi NPS are indicated in Table 1. Moreover, the risk

levels of each risk source expressed using Hazard Potential and Safety Management are shownin Fig. 3.
In the Mid-and-Long-term Roadmap, management of these risk sources is classified into thethree broad categories: [1] Highly contaminated water and fuel in SFP, etc., relatively high risks
given a high priority, [2] Fuel debris, etc., risks unlikely to appear immediately though, risks may
grow in case dealing with haste, [3] Solid waste, etc. risks unlikely to increase in the future, but
appropriate decommissioning efforts necessary. The appropriate measures are taken by giving
these priorities. Risk reduction strategies for each of these sources will be described in Chapter 3.
In regards to fuel in SFPs, the testing on SFP cooling shutdown was performed, and it was foundthat rise in water temperature after cooling shutdown was slower than expected. By incorporating
this finding, the risk of fuel in SFPs is lower than previously evaluated, because the time margin
before this risk becomes apparent increases.

Table 1 Major risk sources of the Fukushima Daiichi NPS
Fuel debris
Spent fuel

Fuel debris in the RPVs/PCVs in Units 1 to 3
Fuel in SFPs

Fuel assemblies stored in the spent fuel pools (SFPs) in
Units 1 to 3

Fuel in the common

Fuel assemblies stored in the common spent fuelspent fuel storage poolstorage pool

Fuel in dry casks

Fuel assemblies stored in dry casks

Contaminated Stagnant waterContaminated water accumulated in the reactor

water etc.

buildings and turbine buildings in Units 1 to 4, mainin the buildings

process building, and high temperature incinerator
building.

6

Stored water

Strontium-treated water and ALPS treated water stored

in welded tanks

in welded tanks

Residual water in flange Concentrated salt water, strontium-treated water andtanks

ALPS-treated water remaining in the bottom of flange
tanks

Secondary

Waste adsorption

Spent adsorbent used in the cesium adsorption

waste fromcolumns

apparatus, the second cesium adsorption apparatus,

water

high-performance ALPS, mobile-type strontium removal

treatment

equipment, second mobile-type strontium removal

systems

equipment and mobile-type treatment equipment, etc.
HIC slurry

Slurry produced during the treatment by ALPS andstored in high integrity containers (HIC)

Waste sludge

Precipitation from the decontamination instruments

Concentrated liquid

Concentrated liquid waste generated by evaporative

waste, etc.

concentration of concentrated salt water and carbonate
slurry collected from concentrated liquid waste

Rubble,Solid waste storage

Rubble with high radiation dose rate (30mSv/h andetc.

facility

above) stored in the solid waste storage facility

Soil covered temporary

Rubble stored in Soil covered temporary storage facility,

storage, etc.

Temporary storage tent and Outdoor container storage(1～30mSv/h), and Felled tree stored in Temporarystorage tankOutdoor storage, etc.

Rubble stored in Outdoor seat covered storage (0.1～
1mSv/h), Rubble stored in Outdoor storage (Under
0.1mSv/h), and Felled tree stored in Outdoor storage

Contaminated structures, etc. in the

Structures, pipes, components, and other items insidebuildings

the reactor buildings, PCVs or RPVs that arecontaminated with radioactive materials dispersed dueto the accident; and activated materials from operation
before the accident

The previous Strategic Plans have focused on the risk source containing radioactive-richmaterials. On the other hand, when aiming at the entire operation of decommissioning processes
from a long-term perspective, there exist what should be addressed regardless of amounts ofradioactive materials and the waste that have generated before the accident. Therefore, the survey
has just begun in wider range of the target to identify what need long-term strategic study.

7

Hazard Potential (logarithmic scale)

Region of sufficiently
stable management

Fuels indry casks(March, 2019)

Fuels incommonFuel debris
pool
ContaminatedUnit 1structures in bldgs. Unit 3
HIC
Waste
Fuels inslurry Uint 2
absorption
Unit 3 Unit 2 SFPs
columns
Unit 1
Waste
Concentrated sludge Stagnant waterin bldgs.
liquid waste, etc.

Rubble inStored water
storage
in welded tanks
facility
Soil covered
temporarystorage, etc.

Residual waterin franged tanks

Outdoorstorage, etc.

Safety Management (logarithmic scale)Fig.3 Example of risk levels assigned to the risk sources at the Fukushima Daiichi NPS
iii. Approach to risk reduction strategies and future direction(1) Interim goal of risk reduction strategies
Risk reduction strategies include reduction in Hazard Potential and Safety Management in the
SED. The examples of reduction in Hazard Potential include decrease in inventory and decay heatassociated with radioactive decay, and changing the form of liquid and gas into the form that is hardto move. To process contaminated water to change into the secondary waste is an example of formchange.
The examples of reduction in Safety Management include transfer of fuel in SFPs to the common
spent fuel storage pool, and placement of rubbles stored outside to the storage. Of the various risk
reduction measures, the reduction in Safety Management is considered generally to be easily
achieved. Therefore, the interim goal of risk reduction strategies is to bring the risk levels into the“Region of sufficiently stable management” (pale blue area) indicated in Fig. 3.
SED quantitatively shows a current condition of a risk of radioactive materials, and this is aneffective method to determine the order of priority for measures against risk sources. When
conducting actual risk reducing approach, it is required to take measures from engineering aspect
in order to inhibit development of risks from radioactive materials associate with its operation.

8

(2) Basic approach to risk reduction
The decommissioning of the Fukushima Daiichi NPS is a project with inherent considerable
uncertainty. To date, internal status of the Units 1 to 3 is estimated to some extent by simulation of
the development process of accident, estimation of location of fuel debris by measurement of muon,
projection of inspection equipment into PCV, radiation dose measurement in the buildings andothers. However, to eliminate uncertainty, many resources, especially a considerably long time, arerequired. To realize prompt risk reduction, it is necessary to make integrated decisions taking
flexible and prompt approach, based on the directions determined with previously obtained
experience and knowledge and with experiment- and analysis-based simulation, placing safety at
the top priority, even though a certain extent of uncertainty remains. At this time, it is important toflexibly address the issues with experiences, reflecting the internal information, technical feasibility
and other information obtained in advance in a certain unit on the subsequent works and the works
in other units. As the viewpoint to make integrated decisions like this, NDF summarizes thefollowing five guiding principles.
(Five guiding principles)

Safe

Reduction of risks posed by radioactive materials and ensuring worksafety

ProvenHighly reliable and flexible technologies



Efficient

Effective utilization of resources (e.g. human, physical, financial andspace)

TimelyAwareness of time axis



Field-oriented

Thorough application of Three Actuals (actual field, actual things andactual situation)

These guiding principle are the viewpoint necessary to discuss priority of approaches and total
optimization.
(3) Order of priority
It is important to be aware of position of each project and their mutual relationship in theirrespective fields in managing progress of overall project based on the five guiding principles.
Specifically, as the situation on site is gradually becoming clear along with progress indecommissioning operation, when applied this five guiding principles into the actual site, at present,
decommissioning which optimal balance is considered is needed while focusing on “safety” and“certainty” including radiation exposure inhibition or ensuring safety and reliability of devices andequipment during operations. In the decommissioning of the Fukushima Daiichi NPS that aspires
to a continuous and prompt risk reducing, it is important to aim at choosing the best option among
the various possible options, with the integrated viewpoint of looking at the entire site on a longterm basis and considering time axis. Taking into account such point of view, TEPCO and NDF
have just introduced project management mechanism and addressed to enforce the efforts.

9(4) Concept of securing safety and promotion of cooperation
While the approaches to facilitate decommissioning such as fuel debris retrieval will contributeto stabilizing the Fukushima Daiichi NPS, conducting these approaches comes with certain risks.
Although these risks must be minimized, excessive protective measures are taken to these risks
may make conducting these risks difficult. Meanwhile, it is also necessary to determine anappropriate approach to safety by taking the unpreceded situation into consideration, such as
significant uncertainties of the situation and the difficulties in implementing measures due to highradiation dose conditions on site.
In light of these circumstances, the concept for determining an appropriate approach to safety(Concept of securing safety) during decommissioning is being examined in cooperation withTEPCO and the manufactures and designers of facilities at the initiative of NDF. Specific items on
the agenda for these discussions include;Establishment of the judgement criteria and safety assessment methods that are applicableto the decommissioning work at the Fukushima Daiichi NPS; and

Safety assessment of typical accident scenarios set up for fuel debris retrieval work, andways to determine appropriate safety measures based on the assessment results.

TEPCO and the Agency for Natural Resources and Energy and other organizations will continue
to cooperate and proceed with those discussions under the initiative of NDF, as well as
communicate actively with the Nuclear Regulation Authority, because it is needed to develop theconsensus on the concept for determining rational safety measures for the decommissioning
operation of Fukushima Daiichi NPS.
(5) Addressing temporary increase of risk level associated with the decommissioning
operations
As mentioned earlier, the implementation of the decommissioning work is striving for prompt risk
reduction from the mid-and-long-term viewpoint. However, it requires careful consideration of thepossibilities that the performance of decommissioning work may temporarily change the risk levels
and may increase the radiation exposure of workers. This possibility of a temporary increase in therisk level and a rise in workers’ radiation exposure arising from the decommissioning work must be
addressed by ensuring measures to prevent and restrict them. It is imperative to limit the increasein the risk level during the decommissioning work within the permissible range by thoroughpreparations for the work. In particular, the radiation safety of workers should be ensured inaccordance with the concept of ALARA (to suppress radiation exposure As Low As Reasonably
Achievable).
Note that the basic stance of promptly implementing the decommissioning must be firmly
maintained because if the decommissioning work is delayed excessively, existing high risks willremain over the long term and their risk levels can gradually increase as the buildings and facilities
deteriorate over time. For this reason, regard to the selection of the method of work, the design and

10

production of equipment and safety systems, and the development of work plans for thedecommissioning work, cautious and comprehensive decision making is required for the early
implementation of the decommissioning in consideration of many constraints such as time, cost
and workers’ radiation exposure needed for associated preparations and work, while giving priority
to limiting the risks involved in the decommissioning work.
Moreover, the decommissioning of the Fukushima Daiichi NPS as a risk reduction project should
be promoted, gaining the broad understanding and support by wide range of public local residents
as well as parties concerned. Therefore, it is important to implement an easy-to-understandmechanism of monitoring of risks such as how the overall risks at the NPS have been continuously
reduced through the decommissioning work. Such mechanism is now being studied in NDF and it
is also important for TEPCO to study on introducing it in the future.

11

3 Technological strategies
Fukushima Daiichi NPS

towarddecommissioning

of

the

1) Fuel debris retrieval
i.

Sectoral target(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) Toward determination of fuel debris retrieval method for the first implementing unit in FY 2019,and start of fuel debris retrieval work for the first implementing unit in 2021, necessary
approaches will be taken, according to the “Policy on Fuel Debris Retrieval”.

<Key Points of the "Policy on Fuel Debris Retrieval">[1] Step-by-step approachIn order to reduce associated risks as early enough, flexibly coordinate the direction basedon information that comes out as retrieval proceeds, after setting method of fuel debris
retrieval to be started first.
Retrieval operation and internal investigation should be performed in a coordinated,
integrated manner.
Retrieval starts from a small-scale and the scale of retrieval should be expanded by stepup.

[2] Optimization of entire decommissioning workExamine retrieval work as a comprehensive project aimed at total optimization, including
coordination with other construction works at the site.

[3] Combination of multiple methods
Combine the optimum retrieval methods for each unit, depending on the locations wherefuel debris is considered to be present.

[4] Approach focused on partial submersion method

Make efforts to focus on a more feasible partial submersion method[5] Prioritizing fuel debris retrieval by side access to the bottom of the PCVii.

It should be considered that the accessibility to fuel debris and the removal of spent fuelcan be accomplished in parallel from the view point of mitigating risks from fuel debris as
early enough while minimizing any increase in risks that might be caused by retrieval.

Sectoral Strategies(1) Approach to risk reduction in fuel debris retrieval work
It is hard to consider that the fuel debris immediately appears as a risk, but it is a risk source thatrisk may grow in case of dealing with rush and haste. On the other hand, the fuel debris is currently
maintained in a state with a certain level of stability; however, on a long-term, the possibility ofchanges in the form and physical property due to aging degradation is considered. For this reason,
as indicated in (1) of Sectoral targets, fuel debris should be retrieved safely after thorough andcareful preparations such as safety measures and bring it to the state of stable storage that is fully

12managed as early as possible. To realize this, it is important to well organize and examine thematters to be considered, such as securing of safety during fuel debris retrieval and technicalrequirements including feasibility of fuel debris retrieval methods and stable storage of fuel debris.
According to the concept of the fuel debris retrieval policy, the retrieval starts from accessing to
the bottom of PCV from its side by partial submersion method using a remote operation equipment.
Retrieving of fuel debris by partial submersion method is unprecedented project in the world. It isnecessary to proceed with operation carefully upon enough and well making preparations in orderto properly inhibit increase of risk associated with its operation, due to the limited information on
the internal condition of PCV in Units 1 to 3. At the beginning, it should be appropriate to start from
retrieval based on use of existing safety system, with no significant changes in the state of the site
including condition of PCV. Specifically, retrieval should start from small-scale from the scope thatcan be conducted by utilizing existing penetration, without making major changes in the state such
like processing PCV wall. This allows continuations a series of operations from containing andtransferring through storing steadily after retrieving fuel debris without giving non-reversible statechanges to PCV, and to reduce the risk from fuel debris and to conduct confirmations ofeffectiveness of systems and internal conditions required for further operations to be developed.
Through small-scale retrieval in the first implementation unit, the following effects can be
expected:①

Enables verification of equipment, facilities and safety systems, including remote operationsin the phase of small-scale retrieval by obtaining information (including radionuclide migration
rate to gas phase and liquid phase) on the effectiveness and work efficiency reviews ofequipment, facilities, and safety systems from fuel debris retrieval to containment, transfer,and storage.

②

Enables use of work experience gained from fuel debris retrieval to containment, transfer, andstorage including remote operations as the process to master fuel debris retrieval operations
for TEPCO.

③

Enables acquisition of information that contributes to understanding situation inside the PCV(fuel debris distribution [Including characteristics], information on access routes, information
on structural conditions, etc.).
Since then, amount of retrieved fuel debris shall be increased or further retrieval shall be started

from units other than the first implementing unit after taking necessary measures such as expansion
and modification of PCV openings, installation of new openings, expansion of scale of remote
operation equipment, and addition of new equipment for securing safety, based on the new findings
including information and experiences acquired through this small-scale retrieval operation of thefirst implementing unit. Fuel debris retrieval at expanded-scale mentioned above or at units otherthan the first implementing unit will require following items of development.
a) Consideration of actual site applicability based on such as conceptual study on safety system

13b) Information organization such as radio nuclide airborne release fractions for examining
necessary and sufficient safety systemsc) Site environment preparation such as radiation reduction, water level lowering in PCV and areaplanningd) Further understanding of inside condition of PCV and RPVe) Technologies to make efficient fuel debris retrieval including removing obstaclesf)Technologies to reduce dispersion of radionuclide airborne particles during fuel debris retrievalg) Consideration on sorting and distinction of fuel debris and radioactive wasteh) Technologies to analyze and estimate fuel debris properties and distributions for understanding
In such manner, fuel debris retrieval of the first implementing unit will be contentiously examined.
Also engineering regarding new safety systems on its site applicability, site environmental
preparation, PCV internal investigation and necessary R&D shall be conducted continuously.
(2) Fuel debris retrieval method for the first implementing unit (Outline of the strategic
recommendation for determining the fuel debris retrieval methods for the first
implementing unit)
The Mid-and-Long-Term Roadmap revised in September 2017 stipulates that "Regarding themethod of fuel debris retrieval for the first implementing unit to begin the operation, which will start
within 2021 by determining the method of containing, transfer and storage (by 2019) after due
consideration of the results of the preliminary engineering and R&D".
In response to this, the first implementing unit and its fuel debris retrieval method have been
investigated, and the results are summarized as the “Strategic Recommendation for Determining
the Fuel Debris Retrieval Methods for the First implementing unit”. The recommendations fordetermining the fuel debris retrieval methods for the first implementing unit has been concluded
through the examination of overall optimization of the combination of the whole site planning andfuel retrieval scenarios of each unit which were established based on the evaluation of theconceptual design of fuel debris retrieval systems and its field applicability to each unit created asa result of preliminary engineering by TEPCO using the past research and development results
and the PCV internal investigation results The flow of the above mentioned process is as shown in
Fig.4.
As a result of the above mentioned examination, selected “fuel debris retrieval work”, which canbe defined as a series of operation from containment, transferring and then storing in steadycondition, is to start promptly from small-scale retrieval operation keeping in a minimum riskincrease caused by fuel debris retrieval work and to accumulate experiences and knowledge
immediately for expanded-scale retrieval work as well as units other than the first implementing
unit. This approach of fuel debris retrieval operation enables to reduce risk existing in Units 1, 2
and 3. In particular, operation starting from gripping and sucking by using an arm-type accessequipment that field applicability is getting in sight and the air tightened enclosure that contains

14arm-type access equipment combined with existing safety system and without significant
modification is evaluated possible to retrieve fuel debris “safely”, “reliably” and “promptly”.
Moreover, proposed method of containing, transfer and storage of retrieved fuel debris, that
retrieved fuel debris firstly contained in a small container is transferred and contained in the canisterand stored in dry condition at the temporary storage facility built within Fukushima Daiichi NPS site,is also judged to be able to contain, transfer and storing the retrieved fuel debris “safely”, “reliably”
and “promptly”. The schematic drawing about fuel debris retrieval and handling (containing, transfer
and storage) is shown in Fig.5.
From the view point of optimization of entire decommissioning work of Fukushima Daiichi NPS,
Unit 2 is currently judged to be appropriate for the first implementing unit. Its reasons are that thesufficient information on PCV internal condition and site condition (radiation dose, degree of air
tightness by the existing safety system) has been obtained as well as that information andexperiences on fuel retrieval work can be promptly obtained by starting its fuel retrieval work in a“safe”, “reliable” and “prompt” manner, based on site condition such that fuel debris retrieval workand fuel removal work from SFP can be done in parallel. Small-scale of fuel debris retrieval
operation starting at Unit 2 enables to reduce of risk existing in Units 1, 2 and 3.
In Unit 2, in this way, fuel debris will be retrieved by using the arm-type access equipment, anda series of tasks from retrieving, containing, transferring, and storing fuel debris should becontinued safely and reliably, then information/experiences required for further implementation
should be gained promptly.
The points of recommendations for determining the fuel debris retrieval method of the first
implementing unit, which were obtained from the results of these examinations and evaluations,are as follows:① Fuel debris retrieval work is to start from small-scale operation such as gripping and sucking
by using the arm-type access equipment that actual site applicability is getting in sight andthe air tightened enclosure that contains the arm-type access equipment combined withexisting safety system without significant modification.
② Using information and experiences accumulated through fuel debris retrieval operations bygripping and sucking, crushing method for fuel debris retrieval and removing of obstacles
are to be studied. Fuel debris retrieval by crushing or cutting during the small-scale fueldebris retrieval work phase is also to be performed under without significant modification ofexisting safety system.
③ Retrieved fuel debris firstly contained in the small container is transferred, contained into thecanister and stored in dry condition at the temporary storage facility built within Fukushima
Daiichi NPS site.
④ From the view point of optimization of entire decommissioning work of Fukushima Daiichi
NPS, Unit 2 is currently judged to be appropriate for the first implementing unit. Thus, aseries of operations from fuel debris retrieval to containing, transferring and storing of the15

retrieved fuel debris will be continued at Unit 2, and information and experiences will be
accumulated necessary for expanded-scale of fuel debris retrieval work in the future.
However, certain hold points should be appropriately defined on the process of necessary
study or planning to start fuel debris retrieval work for verifying the appropriateness of current
study/planning.
⑤ Retrieval methods including containing, transferring and storing the retrieved fuel debris
applicable for the expanded-scale of fuel debris retrieval work phase or other than the first
implementing unit need to be established by proceeding with PCV internal investigation,necessary R&D and improvement of working environment such as lowering of PCV waterlevel, radiation dose reduction and securing working space, as well as engineering of newsafety system, fuel debris retrieval and storage facility using accumulated information andexperience through fuel debris retrieval work of the first implementing unit including study
on safety evaluation and actual site applicability of above mentioned engineering results.
The "Strategic Recommendation for Determining the Fuel Debris Retrieval methods for the First
implementing unit" also discusses the efforts need to be made toward the fuel debris retrieval in
the first implementing unit and expanding scale and retrieval in units other than the first
implementing unit, which is described later in iii (1).

16

Progress of ancillary R&D and
PCV internal investigation

Progress of work environment
improvement

Progress of site-wideplanning•••

It was observed that there are some
movable pebble size deposits in
Unit 2.
Get development of arm-typeaccess equipment and the canisterfor retrieved fuel debris into shape.

•

In contrast with relatively low radiationdose in Unit 2, radiation dose
reduction is needed in Units 1&3 aswell as lowering of water level in PCV
in Unit 3.

Study on concept of fuel debris retrieval
•
•

•
•

Use of existing safety system.
Use of arm-type access equipment that actual site
applicability is getting in sight and use of air-tightend
enclosure which contains it.
Start from small-scale retrieval by such gripping or
sucking, and progress to plan fuel debris retrieval bycrushing.
Contain retrieved fuel debris in a small canister,transfer it, contain it in a canister and stored it in dry
condition at the temporary storage facility within site

Fuel removal operation from
SFP completes in Unit 3 first.
Fuel debris retrieval work andspent fuel removal work can bedone in parallel at every unit.

Study result of actual site applicability of fueldebris retrieval work by Unit•••

Unit 1: Maintaining relatively high airtightness with current
safety system, but the radiation dose is high in working
environment and deposits potential of fuel debris andaccess route to reach them are unidentified.
Unit 2: Maintaining high airtightness with current safetysystem and the radiation dose is relatively low in working
environment, deposits potential of fuel debris is movable
and access route to reach them has been identified.
Unit 3: Deposits potential of fuel debris and access routeto reach them has been identified, but airtight level withcurrent safety system is lower than Units 1&2, theradiation dose is relatively high in working environment.

Comprehensive assessment【 Fuel debris retrieval method】 →The arm-type access equipment & the canister enables to retrievefuel debris safely, reliably and promptly.
- Actual site applicability of the arm-type access equipment/canister for retrieved fuel debris are getting in sigh.

【 The first implementing unit】 → Unit 2 is judged to be appropriate because fuel debris retrieval can bestarted “safely”, “reliably” and “promptly” and overall
decommissioning work can be optimized.
- Safe: The radiation dose in working environment is relatively lower than other units and the airtightness with existing
safety system is higher than other units.
- Reliable : Some deposits with potential for fuel debris are movable, and access route to reach them has been identified.
- Prompt : It has a possibility to start fuel debris retrieval work promptly, as well as to accumulate information andexperiences on fuel debris retrieval work.

Unit 2 has potential to reduce risks resulted from entire fuel debris at unit 1, 2 and 3 promptly because theessential information and experiences will be accumulated necessary for expanded scale of fuel debris
retrieval work in the future through a series of operations from fuel debris retrieval by using the arm-typeaccess equipment to containing, transfer and storage of the retrieved fuel debris safely, reliably and promptly.

The points to be recommended for determining fuel debris retrieval method of the first implementing unit
① Fuel debris retrieval work is to start from small-scale operation such as gripping and sucking by using the arm-typeaccess equipment that actual site applicability is getting in sight and the air tightened enclosure that contains the armtype access equipment combined with existing safety system without significant modification.
② Using information and experiences accumulated through fuel debris retrieval operations by gripping and sucking,crushing method for fuel debris retrieval and removing of obstacles are to be studied. Fuel debris retrieval by crushingor cutting during the small-scale fuel debris retrieval work phase is also to be performed under without significant
modification of existing safety system.
③ Retrieved fuel debris firstly contained in the small container is transferred, contained into the canister and stored in dry
condition at the temporary storage facility built within Fukushima Daiichi NPS site.
④ From the view point of optimization of entire decommissioning work of Fukushima Daiichi NPS, unit 2 is currently
judged to be appropriate for the first implementing unit. Thus, a series of operations from fuel debris retrieval tocontaining, transferring and storing of the retrieved fuel debris will be continued at unit 2, and information andexperience will be accumulated necessary for expanded-scale of fuel debris retrieval work in the future. However,certain hold points should be appropriately defined on the process of necessary study or planning to start fuel debris
retrieval work for verifying the appropriateness of current study/planning.
⑤ Retrieval methods including containing, transferring and storing the retrieved fuel debris applicable for the expandedscale of fuel debris retrieval work phase or other than the first implementing unit need to be established by proceedingwith PCV internal investigation, necessary R&D and improvement of working environment such as lowering of PCV
water level, radiation dose reduction and securing working space, as well as engineering of new safety system, fueldebris retrieval and storage facility using accumulated information and experience through fuel debris retrieval work of
the first implementing unit including study on safety evaluation and actual site applicability of engineering results.

Fig.4 Flow of Examinations on "Strategic Recommendation for Determining the Fuel Debris
Retrieval Methods for the First implementing Unit"

17

<Conceptual drawing of fuel debris retrieval>
Spent fuelX-6 penetration
X-6 penetration connection structure

Arm-type access equipment (during surveillance)

Grating on the 1st floor

EnclosureArm-type access equipment (in store)

CRD housing
Pedestal

CRD rail

Reactorcore

Platform
Water level
inside the PCV
Water depth ofApprox. 30 cm

Personal
Entrance

Pedestal opening part (ground floor)

Connecting tube

Fuel debris

Lifting tool withradiation shield

Canister for
temporary storage

Transfer Container

Acceptance/measurement cell

On-site Transfer
vehicleEnclosure

Delivery cell

Remote Transfer Truck
Equipment for small-scale
fuel debris retrieval

Delivery cellfor analysis

Temporarystorage cell

Sample bottle

Small debris container

Reactor Building

Off-sitetransport cask
(Sampling container)

To an analytical facility<Conceptual drawing of fuel debris containment, transfer and storage>

Outdoor (on-site)

Storage Facility(TEPCO material edited by NDF)

Fig. 5 Conceptual drawing of fuel debris retrieval, containment, transfer, and storage(3) Continued internal investigation and accelerated/prioritized R&D
Fuel debris retrieval will proceed according to the step-by-step approach that allows to flexibly
coordinate the direction based on the information gradually obtained. Then, it is important toimplement internal investigations steadily to understand the initial condition of PCV.
As for understanding about internal investigation of PCV, various information has been gained
as a result of internal investigation of PCV that have been conducted so far. However, internal
investigation of RPV has not been made and grasping of the internal condition of PCV and RPV islimited as a matter of fact. Thus, research and development (R&D) to implement internal
investigation of PCV for collecting more detailed data such as distribution of deposits and fueldebris are underway as well as R&D to implement internal investigation of RPV for obtaining
information about the internal condition of RPV.
As internal investigation of PCV, it should be implemented after thoroughly identified what kindof data is necessary. The required data which are distribution (and feature) of deposits and fueldebris inside PCV, information for access route and one for structural condition, are identified fromthe continuous project in preparing for fuel debris retrieval, which is progressing with step by step
approach.
Analyses and investigations on the decommissioning and contaminated water management ofFukushima Daiichi NPS should be implemented within the range of efforts to proceed withdecommissioning safely and steadily, since the top priority is to realize decommissioning safely and18

steadily as early as possible. The necessity to implement these analyses and investigations should
be sufficiently considered from the viewpoint of investigating the cause of the accident andimproving the safety of nuclear power in the future. After clarifying how the information obtained
will contribute to decommissioning, these analyses and investigations should be conducted to theextent that it is reasonably acceptable as a decommissioning project based on the considerationof their significance and the associated burden. Therefore, Analyses and examination on thedecommissioning and contaminated water management of Fukushima Daiichi NPS should be
intentionally implemented, and their plan should be decided during the engineering process along
the basic consideration on intentional implement of analyses and examination on thedecommissioning and contaminated water of Fukushima Daiichi NPS.3
Acceleration and prioritization for R&D, including the establishment of a containment function on
the assumption of the presence of α-nuclides and technology to control the water level in PCV, areencouraged based on the decision of advancing the side access to the bottom of PCV that has
been made according to the fuel debris retrieval policy, as well as focusing on the partial
submersion method. Preparing for expanding the scale of retrieval, it is important to obtain more
information about internal condition of PCV and RPV, to proceed with technological developments
to optimize efficiency of retrieval work, to reduce diffusion of radioactive fine particles during
retrieval operation, to classify fuel debris and waste, and to analyze and examine the characteristicof fuel debris. In addition, it is also important to proceed with technological development whichassume how to respond to the top access method for fuel debris retrieval. In the future, it will benecessary to strengthen R&D management on a project basis by identifying R&D tasks required
through engineering studies and implementing them in a timely and appropriate manner.
iii. Technical Issues for promoting sectoral strategies and future plans(1) Technical issues and plans related to the fuel debris retrieval from the first
implementing unita. Initiatives toward start of retrieving fuel debris from the first implementing unit
Considerations should be given to the fuel debris retrieval for the first implementing unit inaccordance with the recommendations for determining the methods of retrieving fuel debris for the
first implementing unit as described in ii (2).
To safely and reliably retrieve fuel debris for the first implementing unit, it is necessary toappropriately provide hold points in the course of engineering activities by TEPCO considering theelements such as validation of safety and actual site applicability at the occasion of mock-up testing

TEPCO, The basic principles toward the planned analysis and investigation on the decommissioning
and contaminated water management of Fukushima Daiichi NPS, Handout 4-1 from The secretariat
Meeting of 67th Team meeting on decommissioning and contaminated water treatment, issued on June27, 2019
http://www.meti.go.jp/earthquake/nuclear/decommissioning/committee/osensuitaisakuteam/2019/06/41-1.pdf
319

regarding small-scale retrieval equipment and verification on accessibility at the PCV internal
investigation, then to proceed with the retrieval operation while confirming validity.
To make decision on the method of fuel debris retrieval of the first implementing unit, it is also
required to pay attentions to the work schedule examination based on the issues through PCVinternal investigations and work interference examination based on the considerations on the fuelremoval method from SFP as mentioned followings.


It becomes apparent through PCV internal investigation that there are obstacles in the accessroute to the fuel debris and improvement of measures to prevent dust diffusion is necessary
when removing such obstacles. Accordingly detail planning and examination on work scheduleaiming at start of fuel debris retrieval shall be promoted, considering removal method of the
obstacles including enhancement of prevention of radioactive airborne material diffusion during
obstacles removal work.

It becomes apparent through PCV internal investigation, research & development andpreliminary engineering by TEPCO that the works such as installation of the enclosure require
many human works at the site. Accordingly detail planning and examination on work scheduleaiming at start of fuel debris retrieval shall be promoted, considering further reduction methodof the radiation dose rate at the first floor of R/B(about 5mSv/h) where most human works takeplace.

It is observed through the investigation of operating floor of Unit 2 that the radiation dose isreduced so that human works would be available to some limited extent. Several plans are
considered on the fuel removal from SFP with method to reduce risk of dust diffusion.
Accordingly coordination of work interferences when making parallel works both for fuel removalfrom SFP and fuel debris retrieval including preparation works shall be well examined based on
the progress of engineering on method of fuel removal from SFP.
Toward start of retrieving the fuel debris for the first implement unit, TEPCO announced a planof the future internal investigations in July, 2018. For Unit 2, it is scheduled to conduct ① deposit
contact investigation, ② investigation to grasp the distribution of deposits as well as sampling insmall amount of deposits, and ③ sampling in larger amount of deposits. The status and purposeof each investigation and sampling are as follows.
① The deposit contact investigation was implemented in February, 2019. The purpose is tocontact the deposits and to check the change of the state before and after contacting. As results,
it is confirmed that deposits which are considered as the fuel debris are able to be moved bygrasping.
② The investigation to grasp the distribution of deposits as well as sampling in small amount ofdeposits is scheduled to be implemented in future, and it is appropriate to be conducted before
start of retrieving the fuel debris for the first implement unit. The purposes are a) to confirm thatthe arm type access equipment can go into PCV, and b) to characterize the fuel debris by20

analysis.
③ The plan of sampling in larger amount of deposits is under consideration now. The purposes
are a) to confirm that the fuel debris retrieval can be carried out, and b) to characterize the fueldebris by analysis using larger amount of deposits.
The start of retrieving fuel debris was scheduled to be conducted after confirming a) of ③, thisconfirmation is evaluated so far to be obtained by the confirmations in ① and ②. In addition, thefuel debris retrieval in small amount is scheduled to start by gripping and sucking, and the datarequired for assessment of cutting the fuel debris, etc. is evaluated so for to be obtained bysampling in larger amount of fuel debris by using the same equipment as that for fuel debris retrieval
in small amount. Thus, the fuel debris retrieval for the first implementing unit is possible to be
integrally conducted with ③, and by this procedure it is possible to reduce the total amount ofworkers’ radiation exposure and waste. Therefore, it is appropriate to revise a plan that the fueldebris retrieval for the first implement unit and ③ is scheduled to be integrally carried out.
b. Initiatives for expanding retrieval scale and retrieval in units other than the first
implementing unit
Retrieval will start from small-scale with no significant changes in the state of the site in using
existing safety system as a base, and expand the scale or retrieve fuel debris from units other than
the first implementing unit based on new findings including information and experiences acquired
from the small-scale retrieval operation. To allow for this, following activities are necessary.
a) Consideration of actual site applicability based on such as conceptual study on safety systemb) Information organization such as radionuclide airborne release fractions for examining
necessary and sufficient safety systemsc) Site environment preparation such as radiation dose reduction, water level lowering in PCV
and area planningd) Further understanding of inside condition of PCV and RPVe) Technologies to make efficient fuel debris retrieval including removing obstaclesf)Technologies to reduce dispersion of radionuclide airborne particles during fuel debris retrievalg) Consideration on sorting and distinction of fuel debris and radioactive wasteh) Technologies to analyze and estimate fuel debris properties and distributions for understanding
In this regard, improving site work environment, PCV internal investigation and R&D arecontinued, regarding to the retrieval method in case of expanding the scale or applied to the units
other than the first implementing unit. The retrieval method in conjunction with containing,transferring and storage should be determined after proceeding with engineering to examine newsafety system, retrieval facilities and the prospect of their actual site applicability, which is basedon the information and experiences obtained through fuel debris retrieval for the first implementing
unit.

21

Since fuel debris retrieval is carried out in parallel with other works, it is necessary to revise thework plan in accordance with the overall situation of decommissioning activities. Especially in orderto realize the regular full-scale fuel debris retrieval safely and smoothly, efficient site space planwith appropriate margin is an important issue by keeping stably available area in the site.
Furthermore, the way of fuel debris retrieval shall be flexibly considered in view of optimizationof total decommissioning activities, as example the retrieval at the units other than the first
implementing unit can start if prepared well, even though the retrieval of the first implementing unit
is still continuing.
(2) Comprehensive understanding of conditions inner PCV by continued internal
investigation
The comprehensive analysis and the evaluation results about the access route to fuel debris andthe situation of the surrounding structures and the distribution of fuel debris in Units 1 to 3 areshown in Fig.6, that have been derived from actual measured values of plant parameters, etc.,
which were obtained at the time of accident, severe accident progress analysis, and the knowledge
obtained by internal investigations of PCV and examinations, etc.
In Unit 2, for which an internal investigation is relatively advanced, it is scheduled hereafter to
conduct the internal investigation to grasp the distribution of structures and deposits in the pedestal
and to conduct samplings in small amounts of deposits. In such an internal investigation andsampling, it is necessary to make preparations for the investigation in advance by carefully allowing
a certain time for adequate tests of the investigation equipment and training of its remote control,
because the equipment which would be bigger than before and would be used for handling of
obstacles, etc., will be different from that conducted in the previous investigations. During theinternal investigation and sampling, it is not always necessary to obtain information only on thebottom of the PCV, but it is also important to obtain information necessary for the future work,
including the characteristic (hardness, adherence situation, and elemental composition, etc.) of
deposits adhering on the platform of PCV and the location of internal components.
For Unit 1, grasping of the distribution of structures and deposits outside the pedestal andsampling of deposits in small amounts are scheduled for FY 2019. In addition to this, studies toconfirm the condition inside the pedestal should also be considered.
For Unit 3, it is necessary to examine the applicability of techniques for internal investigations
which

were

developed andverifiedthrough theGovernment-led R&D program on

Decommissioning and Contaminated Water Management, and the necessity of further
investigations by use of the submersible ROV which was used in the previous investigation, inparallel with the examination on the lowering of PCV water level.
For Units 1 and 3, considerations should be given to the method of fuel debris retrieval, in addition
to these internal investigations.

22

In the future, prior to implementing further detailed internal investigations, giving due
considerations will be required for continuous ensuring safety, including maintaining containment
function and prompt recovery during abnormal events as well as measures against radiation
exposure and dust control, since maximum opening size of existing penetrations through which
equipment have gone into the internal PCV in the previous investigations will be used due to theintroduction of larger equipment.
Fuel debris and deposits of Fukushima Daiichi NPS have special aspects that are unparalleledin the world due to the differences of reactor structure and of responding to restoration from theaccident. It is necessary to develop analytical/estimation technology to characterize them becauseof their limited data and higher uncertainty. In particular, it is crucial to demonstrate analyticalmethod for fuel debris by using retrieved samples of fuel debris in order to build analyticaltechnology. In enhancing research facility for analyzing radioactive material, it is important to take
into consideration the demonstrated outcome to proceed with characterizing fuel debris according
to a location of PCV.

23

Unit 3

Unit 2

Unit 1

Spent
fuel

Spent
fuel

REACTOR
CORE

REACTOR
CORE

Unconfirmed, to reflect
results of planned surv ey

Core Region

RPV Lower

Head

REACTORCORE

W ater level
inside the PCV
W ater depth ofApprox. 2 m

W ater level inside
the PCVW ater depth ofApprox. 6 m

W ater level
inside the PCV
W ater depth ofapprox. 30 cm

Personal
entrance

Fuel debris

Spent
fuel

Personal
entrance

Water Leakage (v isual observation)

Fuel debris

Personal
entrance

Water Leakage (v isual observation)

 Little fuel debris remains

 Little fuel debris remains(Stub-shaped fuels might exist in peripheral region)

 A small amount of fuel debris is present
 Large amount of fuel debris is present A small amount of fuel debris is present in the  A small amount of fuel debris is present in
inside and on the outer surface of the CRD
the inside and on the outer surface of the
housing
CRD housing

Fuel debris

Water Leakage (v isual observation)

 Little fuel debris remains
 Fuel debris remains on the RPV lower headparty
 A small amount of fuel debris is present in
the inside and on the outer surface of the
CRD housing

Bottom of PCV
 Most of the fuel debris is present
Pedestal inside A certain amount of fuel debris is present on
the floor of the pedestal inside Amount of fuel debris in Unit 3 is more thanthat in Unit 2.

Bottom of PCV  Fuel debris may have spread on the pedestal
outside through the personal entrance The possibility of fuel debris spreading on
the pedestal outside through the personalentrance is low.

 Fuel debris may have spread on the pedestal
outside through the personal entrance

Radiation dose  Radiation dose rate around penetration X-6
in operation site on the first floor of R/B is high (630mSv/h).
*１

 Radiation dose rate on the first floor of  Radiation dose rate on the first floor of R/B
R/B had reduced by about 5mSv/h.
is higher than tens of mSv/h.

High dose rate

Pedestal Outside

Pedestal

X-6 penetration

Pedestal

CRD housing
X-6 penetration

CRD rail

Pedestal Inside

CRD rail

CRD housing

Unconfirmed, to reflect
results of planned survey

Pedestal

X-53 Penetration

Pedestal Inside
Deposit

X-6 penetration

Pedestal Inside

CRD rail

CRD Guide tube

Grating

Grating

Grating

CRD housing

Unit 3

Unit 2

Unit 1

Grating
Upper tie plate

Supporting
pillar

Cable tray

• It is possible to access to the D/W bottom
from the upper side.
Information on
the access route • State around the CRD rail connecting to theto fuel debris *2 pedestal from the X-6 penetration is notobserved.

• There is no large obstacle on the CRD rail
and around an entrance to the pedestal• It is possible to access to the pedestal inside
inside.
through an entrance.
• It is possible to access to the pedestal insidethrough an entrance.

Information of
the structurearound fueldebris• However a part of fuel assemblies fall, nolarge damage is observed on CRD housing
support.
• No large damage is observed on inner walland structures of the pedestal.

 There is no large damage on the surface ofthe pedestal outer wall above the steel
grating.

• Some damaged structures and the fall of the
CRD housing support were observed in thepedestal inside.
• No large damage is observed on inner wallof the pedestal.

*1 Data provided by TEPCO*2 It is thought that a route to the pedestal inside from the X-6 penetration is important for fuel debris retrieval from a small-scale task by side access method. The
content observed by previous internal investigations are mentioned as information to judge whether trouble will be caused by fallen objects on the route, etc. In
the access route for the fuel debris retrieval in the PCV, an access route through an equipment hatch is under review in the decommissioning and contaminatedwater management project.
Due to high dose rate around the X-6 penetration of Unit 1, it may use the same access route as the larger-scale retrieval in the case it is difficult to improve thework environment. Next internal investigation of Unit 1 is scheduled to develop by accessing from X-2 penetration.

(Prepared by Achievement Report 2017 Subsidy for “the Government-led R&D program on Decommissioning and Contaminated Water Management by the
supplementary budget (Advancement of comprehensive internal PCV condition analysis)” (June 2018) provided by IRID, The Institute of Applied Energy), etc.

Fig.6 Estimation of fuel debris distribution in Units 1 to 3, access route and the condition ofsurrounding structures24

(3) Technical issues on technical requirements and future plansa. Technical issues and future actions for ensuring safety of fuel debris retrieval work
For ensuring the safety of fuel debris retrieval, it is important to study reasonable protective
measures according to the scale of operation while taking actions to reduce the uncertainties of
PCVs’ internal conditions during the conceptual design phases of retrieval method. In theStrategic Plan, along with organizing the concept of ensuring safety, we are focusing on the key
technical requirements for ensuring safety during fuel debris retrieval work as follows.
① Establishing the containment functions (Gas-phase)
As for retrieving of the fuel debris, applicability for the small-scale retrieval starting fromgripping or sucking together with existing safety systems has been investigated and confirmed.
However, the dispersion of radioactive fine particles (α-dust) containing α-nuclides may occur due
to the works such as cutting and drilling fuel debris, and there may be a concern for increasing
the concentration of radioactivity in PCVs gas phase. Therefore, a function for containing the gas
phase should be established to suppress the radiation dose impact on workers and the public
within the allowable value, by minimizing the spread of α-dust from PCV.
In this regard, it is reasonable to expand the scale of the retrieval work while verifying thevalidity of the containment function built in the subsequent stage by grasping the tendency of dust
dispersion at the each stage of scale expansion. For example, during PCV internal investigationsor the small-scale retrieval near future, α-dust dispersion can be managed by reducing amount tobe retrieved or by careful handling of the fuel debris. At this moment, the dust monitoring system
inside and outside PCV should be investigated. And the appropriate measures together with theexisting systems that secure the pressure inside PCV equal or less than outside should be
investigated as well.
If it is evaluated that the expansion of retrieval work may induce effects on the surrounding
environment, further investigation is required for the means to strengthen the containment
function by equalization or negative pressurization inside the PCVs as well as constructing asecondary containment function outside the PCVs.
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 retrieval work would be performed, submerging the fuel debris or by pouring
water over the fuel debris. Dedicated investigation of applicability for the small-scale retrieval
starting from gripping or sucking with existing safety systems has been performed. A large amountof α-particles will flow into cooling water (liquid phase) during crushing for fuel debris or removingof the obstacle. To prevent the cooling water containing α-particles from affecting the environment,
it may be of great importance to establish a cooling water circulation/purification system, and aliquid phase containment function.
For this reason, the investigations, that establish technologies of removing soluble nuclides tobe leached from fuel debris as well as treatment of solid matter trapped by the filter equipped in25the circulating cooling water system, shall be conducted. Also, it is requested to investigate thePCV circulation cooling system which takes the water of the bottom of PCV and injected coolingwater into RPV and has an advantage of preventing dispersion of α-particles.
To establish a reasonable containment function in accordance with scale expansion, it isrational to monitor the radioactive concentration of the cooling water and verify the validity of thecontainment function built in the subsequent stage. For example, if the assumed PCV internal
investigations and small-scale retrieval work would be performed using the current water
circulation system, it may be possible to suppress the increase in the radioactive concentrationof cooling water by reducing the retrieved volume and carefully performing the cutting work, aswith the containment function (gas phase). At this time, it is requested to monitor the circulatingwater system from the viewpoint of investigating the methods to detect the effects induced by the
retrieval work on liquid phase, and also requested to investigate necessity of additional facilities
and installations for the purpose of reducing the concentration of radioactive materials at the inlet
in the existing water treatment systems. Based on the results of monitoring and evaluation of thechanges in the condition of the waste solution containing α-nuclides, the scale of fuel debris
retrieval will likely be expanded gradually. If an abnormal event such as a large volume of coolingwater outflow from a PCV to the torus rooms of a nuclear reactor building occurs, measures
should be taken such that the water level in the torus room be maintained lower than the
groundwater level to prevent the outflow of cooling water to the surrounding ground. For thisreason, it is necessary to establish an appropriate PCV water level and a PCV water level control
system.
③ Maintaining the cooling function
The decay heat of the fuel debris has been decreased dramatically since the core melt
accidents. However, it may be necessary to keep the cooling function to prevent nuclides fromshifting from the liquid phase to the gas phase due to thermal energy during fuel debris retrieval
work. At present, the cold shutdown state is maintained with keeping the temperature well below
100 degree centigrade using cooling water. In addition, during fuel debris retrieval work, it may
be necessary to keep the temperature below the level at which fuel debris retrieval device cancontinue to work without any problems for a long period of time.
To maintain the cooling function at each stage of retrieval scale expansion, the consistency
with other systems should be checked, such as the concept of water level control within the PCVs
for confining the liquid phase, the circulation cooling system and the contaminated water
purification system, etc. Based on the data obtained for each stage of retrieval scale expansion,
it may be necessary to examine and establish the circulation cooling system in the subsequent
stages.
④ Criticality Control
At present, the monitoring of the concentration of rare gas (Xe-135) has shown no sign ofcriticality. Further, it may be pointed out that the possibility of criticality is low based on the26expected state of existence of fuel debris. In addition, even if criticality should occur, its impact
would be small because it is estimated that the fuel debris is dispersed over wide area. To keep
the subcritical condition more reliably, it is important to store retrieved fuel debris stably in acontrolled state, for instance, by storing it into storage cans. To prevent fuel debris from reaching
criticality in the process of retrieving fuel debris, it is necessary to investigate what kind of
conditions during the work would lead to criticality, in the case the shape of the fuel debris or thewater volume changes, and establish an appropriate management method with combinedfunctions of prevention, detection, and termination of criticality.
In the early stage of retrieval, the fuel debris should be retrieved in a way that does not
significantly change the shape of fuel debris. Then, the neutron signal level by the situation of
the composition and characteristics of fuel debris and the fluctuation of the neutron signal in thevicinity of fuel debris handled during the retrieval work should be checked to evaluate thecriticality of the fuel debris, as well as to develop a measures of ensuring prevention of criticality
by, for example, combining the oversight and judgement by operators. Also in the process of
expanding the retrieval scale, any measures associated with increasing retrieved volume of fueldebris will be considered, such as measurement of subcritical condition before fuel debris
retrieval work starting, or taking measures such as placing neutron absorbers.
⑤ Securing structural integrity (earthquake resistance) of the PCVs and reactor buildings
The reactor buildings, PCVs, and reactor pressure vessels (herein after referred to as “RPV”s)experienced the hydrogen explosions when the accident occurred. Further, the radiation
exposure to the high-temperature environment and the corrosion due to seawater injection may
have affected the integrity of the structures. During the period of fuel debris retrieval work, it isnecessary to secure the integrity for the important structures like PCVs and RPVs and to
suppress the deterioration of containment functions of PCVs and reactor buildings, considering
the effect mentioned above against the possible occurrence of a severe earthquake. In addition,
the deterioration of containment function of PCVs and reactor buildings due to corrosion have tobe suppressed during the retrieval work. Furthermore, it may be required to prepare for the
mitigation measures in advance, evaluating the impact on human beings and the environment
induced by the postulated damage to important functions due to a large earthquake.
The previous studies show that the reactor buildings and structural major components of PCV,RPV and pedestal, that supports the RPV of each unit, have relatively large seismic safety margin
against a design basis seismic ground motion Ss (600Gal), taking into account the damage
caused by the accident, degradation over 40 years by corrosion and increased weight of new
facilities required for fuel debris retrieval work. It is necessary to evaluate the seismic safetymargin of R/Bs, PCVs and RPVs in more detail and to implement the countermeasures,
according to the progress of the further PCV internal investigation and the studies of fuel debris
retrieval methods.

27

⑥ Reduction of radiation exposure during work
The main work areas of fuel debris retrieval are high radiation dose areas such as inside thereactor buildings. Also, there comes a need of handling of nuclear fuel materials containing αnuclides from fuel debris with a large internal dose impact. Accordingly, continued strict control
of not only for external exposure but also for internal exposure is essential.
Specifically, it is important to prevent excessive radiation exposure to occupational workers
through appropriate radiation protection schemes depending on the working environment andworking style. Regarding protection from external radiation exposure, the radiation exposure
dose is evaluated considering the radiation sources and the radiation dose rate in the work area.
Then, based on the three principles, namely “time, distance, and shielding", it is needed to takemeasures to keep the radiation exposure dose as low as reasonably achievable. Regarding theprotection from internal exposure, measures such as suppressing dispersion of radioactive dust
and prevention of contamination expansion are being taken and appropriate protective measures
are to be selected depending on the target nuclides, concentration in air and surface
contamination density in the work area, to prevent inhalation ingestion and body pollution.
In addition, adequate radiation exposure control should be conducted after formulated a longterm work plan that includes not to concentrate workers’ radiation exposure on individual workers
and to help reduce whole workers’ radiation exposure.
b. Technical issues and future actions for fuel debris retrieval method① Securing access route
For transporting, installing and unloading the equipment and devices used for fuel debris
retrieval, and transporting fuel debris and waste, access routes should be established byremoving obstacles and reducing the radiation dose to the level at which such tasks can be done
by workers. When establishing new openings in the PCV or the like to construct access routes
to fuel debris, it should be kept in mind to suppressing the release of radioactive materials fromthe PCV and RPV and maintaining the integrity of existing structures.
According to the fuel debris retrieval policy based on the partial submersion method that
advances the side access to the bottom of the PCV, TEPCO is now conducting the engineeringwork. Based on the results of the Government-led R&D program on Decommissioning andContaminated Water Management, an access route from the PCV side opening to the fuel debris
is to be constructed. Then, it will be drawn up a plan in which a side wall opening is made on thereactor building and the side wall opening on the PCV is enlarged as required. In addition, toward
the future scale expansion, it is also important to develop technologies for removing obstacles
and retrieving fuel debris through the top access.
② Development of devices and equipment
Equipment and devices for accessing fuel debris and retrieving them safely, reliably, andefficiently should be developed. In order to flexibly respond to the situation on the site, these28equipment and devices must meet the specifications of radiation resistance, remote operationand maintainability, high reliability, and relief mechanisms that do not disturb the subsequent
work if a trouble occurs.
Accordingly, the development of a retrieval system that can handle various conditions of fueldebris, a fuel debris cutting system, and a dust collecting system, is underway. Furthermore,
techniques for installing retrieval equipment is required. The technologies used for remote
operation, including installing the work cell for establishing radiation shielding and containment
functions (gas phase), boundary connection with existing structures, securing an access routefor the top access and removing obstacles required for each of the top access method and side
access method, are now under development. The developed equipment and devices will be
combined and undergo mock-up tests to verify that the performance mentioned above isdemonstrated in a safe and assuring way at the actual site.
③ Establishment of system equipment and working areas
Prior to retrieving fuel debris, it is required to validate that the safety systems can perform inaccordance with safety requirements and safety functions, also requested to investigate
necessity of additional facilities and installations if required. Then appropriate operation shall betaken. Sufficient spaces for installation, operation, and maintenance, and for installing shields for
reducing radiation exposure to operators should be provided, so that the required environmental
conditions will be satisfied.
The system equipment includes a negative pressure control system required for establishinga containment function (Gas phase), a circulating water cooling/purification system required formaintaining the containment function (Liquid phase) and cooling function, and a criticality control
system required for controlling criticality. Elaboration of measurement systems (pressure,temperature, water level, radiation, etc.), which are essential to monitor the condition inside PCV
prior to fuel debris retrieval, is an important technical items to be conducted. An investigation on
the specific method of implementing an overall system and equipment integrating these systems
should be conducted.
The working area required for installing fuel debris retrieval equipment/related devices andsystem equipment is now being calculated. Considering the handling of the high radiation dosearea in the reactor buildings and interference with other tasks, study of setting up the systems,
including outside of the existing buildings, is underway.
c. Technical issues and future actions for safe and stable storage of fuel debris① Handling of fuel debris (containing, transferring and storing)
Before initiating fuel debris retrieval work, a comprehensive system should be establishedwhich consists of a series of steps from containing, transferring to storing of retrieved fuel debris
furnished with safety functions such as maintaining subcritical condition, containment function,29

countermeasures against hydrogen generation, and cooling. The following examinations are in
progress accordingly.
Drawing up of basic specifications of the canister for retrieved debris storage, that is, overall
length considering its handling, internal diameter in light of work efficiency and maintaining
subcriticality, etc., and planning and implementation of tests to verify the structural integrity of
the canisterExamination of a practical prediction method for hydrogen generation from fuel debris stored
in the canister, and consideration on safe transfer condition using the examination resultsStudy on drying technology applicable to fuel debris in the canister, and consideration on adrying system using this technology
In the future, specific facilities and systems should be developed from containing to storing of
retrieved fuel debris, based on the results of these studies. In addition, further studies should bemade on the specific transfer method, the specific type and size of the storage facility, and others,
taking into account the amount of fuel debris to be retrieved per day and the filling rate of thecanister. In developing specific facilities and systems for handling and storing of retrieved fueldebris, it is also necessary to include responses to safeguards requirements.
It is important to reflect various measurement data collected and accumulated during the smallscale retrieval such as the amount of generated hydrogen, as well as knowledge and experienceson handling fuel debris during the operations from receiving the fuel debris by containers for onsite transfer to storing them at the temporary storage facility, into the design of equipment andfacilities for storing fuel debris safely, reliably, and reasonably at expanding scale of retrieval. In
addition, it is necessary to specify transfer routes and storage facility locations for expandedscale retrieval in light of the usage plan of the entire site.
The Mid-and-Long-term Roadmap states that the processing/disposal method of the retrieved
fuel debris are investigated and fixed during the third phase after starting fuel debris retrieval
work.

② Treatment of radioactive waste during fuel debris retrieval work
During fuel debris retrieval work, a variety of radioactive waste such as replaced ordisassembled structures/parts other than retrieved fuel debris are to be generated frominside/outside of the PCV at each phase of its preparation, retrieval and cleaning work. They
should be properly classified and put under safe storage conditions.
For the preparation of expanded-scale retrieval work phase, it is important to develop
classification criteria toward expanded-scale retrieval in order to appropriately classify suchmaterials as fuel debris or radioactive waste, even if only limited information on the retrieved
material is available in advance. For this reason, it is necessary to consider possible methods toclassify fuel debris and waste based on knowledge and information that will be obtained in future
PCV internal investigations, etc., and to promote survey of component technology and addressof technical challenges, which are necessary for realizing such classification.

30

③ Safeguard policy for fuel debris
For Units 1 to 3 of the Fukushima Daiichi NPS, as fuel assemblies treated as items under thematerial accountancy would no longer maintain their original shape due to melting and thefacilities were broken, the same containment/surveillance systems as the level of pre-accident
could not be applied. And high radiation would restrict the entry into the areas for inspection andverification activities. Accordingly, pre-accident material accountancy and safeguards has beendifficult to be applied and implemented. Therefore, additional safeguards measures are currently
applied under this situation to the Units 1 to 3 as an alternative to ensure no undeclared
movements of nuclear materials.
On the other hand, as fuel debris retrieval work involves the shipment of nuclear material, newmaterial accountancy and safeguards should be considered. It is necessary to have discussion
and share information with IAEA and others in a timely and an appropriate manner in order that
newly established material accountancy and safeguards are realistic, so as not to impose
excessive burden on the on-site activities, and sufficiently transparent. And such an effort has
already started.
Technical issues and future planning described in this article is as shown in Fig. 7.

31

Fiscal Year
Milestones

2019

2020

Determination of fuel debris retrieval methods
for the first implementing unit

2021

2022

2023

Start of fuel debris retrieval
at the first implementing unit

On-site work
Technical reviews for on-site construction
Research and development

Internal investigation etc.
Study for the Government-led R&D program on
Decommissioning and Contaminated Water
Management

Preparation for investigation/ Internal investigation / Characterization of fuel debris (from retrieved sampling, etc.)

Technologies to establish access route
Technologies toestablish access route

Technologies to analyze and estimate fuel debris properties- Development of technologies for in-depth
investigation inside PCV- Development of sampling technologies for retrieving
fuel debris and internal structures- Development of technologies for grasping andanalyzing properties of fuel debris- Development of investigation technologies
inside RPVTransfer method to outside the site
Adaption plan for Safeguards
Additional plan for internal
investigation

Engineering for internal investigation
Fuel debris retrieval

Preparation for small-scale retrieval

Retrieval method (layout, etc.)
Containing/transfer plan
Temporary storage facility plan
Ideas for secure safety

Retrieval equipment
Facilities for containing, transfer
and temporary storage
Measures for securing safety(including modification of existing
facilities)
Safeguards policy→- Small-scale retrieval- Preparation of expanded-scale offuel debris retrieval work

Optimization of retrieval method (layout plan, etc.)
Containing/transfer plan
Storage facility plan
Actual site applicability of measures for securingsafety (Containment, water level control andcriticality control)
Gathering and organizing information for safetyassessment
Improvement of working environment such asradiation dose reduction, PCV water level
lowering and securing working space

Engineering involved with fuel debris retrieval
Study for the Government-led R&D program on
Decommissioning and Contaminated Water
Management

Circulating water
system design

For the investigation of measures toensure safety and safer fuel debris
handling according to expanded-scaleof fuel debris retrieval*Continue as necessary- Development of closed circulation systems forwater inside PCVContinue asnecessary- Development of technologies for retrieving
fuel debris and internal components- Development of technologies for containing,transferring and storing fuel debris* Other R&Ds listed below are to be
performed accordingly.
• Technologies to make efficient fuel debris
retrieval including removing obstacles• Technologies for redueing dispersion ofradio nuclide airborne particles during fueldebris retrieval• Consideration on sorting and distinction offuel debris and radioactive waste• Technologies for analyzing and estimating
characterization of fuel debris

Fig.7 Key technical issues and further planning on fuel debris retrieval（Process chart)

322) Waste managementi.

Sectoral target(1) As the approaches of solid waste storage, the Solid Waste Storage Management Plan (herein
after referred to as “Storage Management Plan”) is appropriately developed, revised andimplemented including waste prevention, volume reduction and monitoring, with updating theestimated amount of solid waste to be generated in the next ten years periodically.
(2) As the approaches for processing/disposal, countermeasures integrated from characterization
to processing/disposal of solid waste are studied from the expert point of view, and theprospects of a processing/disposal method and technology related to its safety should be madeclear by around FY2021.
<Key Points of "Basic Policies on Solid Waste">①

Thorough containment and isolation
Containment and isolation shall be thoroughly carried out so that people will not access toradioactive materials to avoid significant radiation exposure.

②

Reduction of solid waste volume
The amount of solid waste generated during decommissioning shall be reduced to the extent
possible.

③

Promotion of characterization
To promote studies on processing and disposal of solid waste, an appropriate characterization
shall be performed in response to the increase in the number of samples for analysis.

④

Thorough storage
Adequate storage capacity shall be secured for solid waste generated, so that they can be
stored safely and reasonably according to their characteristics within the site of the Fukushima
Daiichi NPS.

⑤

Establishment of selection system of preceding processing methods in consideration of
disposal
Before the technical requirements for disposal are determined, a method of selecting aprocessing (preceding processing) for stabilization and immobilization shall be established to
select a preceding processing method.

⑥

Promotion of effective R&D with a bird’s-eye-view of overall solid waste management
Issues on R&D shall be identified through collaboration among the fields of characterization,
treatment and disposal, with a bird’s-eye-view on the overall solid waste management.

⑦

Efficient implementation of R&D projects from the perspective of overall solid waste
management
For ongoing safe and steady solid waste management, a continuous operational framework
including development of adequate facilities and human resources shall be established.

⑧

Measures to reduce radiation exposure of workers
Thorough radiation exposure control, health control, and safety management in accordancewith relevant laws and regulations shall be established.

33

ii.

Sectoral Strategies(1) The concept of risk reduction in waste management and basic policies on solid waste
The solid waste stored on the sites, such as “rubble, etc.”, is unlikely to increase in risk in the
future, but it is still a source of risk which should make its countermeasures properly in thedecommissioning process. It is in a state where the risk level is generally lower than other majorrisk sources, and it is considered that a constant risk level can be continuously maintained byappropriate maintenance and management in the future.
The challenge on solid waste generated by decommissioning of the Fukushima Daiichi NPS isthe existence of a large volume of waste with various characteristics. For this reason, in addition to
improving the analytical capability for characterization, a flexible and reasonable waste stream (anintegrated flow of measures from characterization to processing/disposal) shall be developed.
Specifically, the relevant organizations should proceed with their efforts based on each role in linewith the basic policies of solid waste management that was compiled in the Mid-and-Long-term
Roadmap, and NDF takes the initiative and proceeds with the technical study on the integrated
countermeasures from the characterization to processing/disposal of solid waste according to thefollowing policies.
(2) Storage
The fundamentals of managing solid waste are to confine not to scatter or leak. Also, it should
be kept isolated in a properly storage place, and managed appropriately by monitoring and so on.
It is important to instill the concept of the waste hierarchy, and raise awareness on reducing thevolume of solid waste to be generated. 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 such as on building waste management facilities to be required basedon the volume. Since the estimated amount of generation fluctuates depending on the progress ofthe decommissioning work in the future, it is necessary to revise the volume estimation once a year
and update the Storage Management Plan as appropriate.
The secondary waste generated by water treatment, which has high fluidity, should be stored
and managed in a more stable and reasonable way, by reducing risk levels through a certain
processing. In general, it is ideal to conduct waste processing based on the technical requirementsof disposal once it is established, if the processing is conducted prior to disposal. However, there
may be cases where processing for stabilization and immobilization are required although thetechnical requirements for disposal are not determined (i.e. preceding processing). Therefore,
study will be continued on how to select the preceding processing method with disposal in mind.
(3) Study on the processing/disposal policy
The Mid-and-Long-term Roadmap specifies that the prospects of a processing/disposal method
and technology related to its safety should be made clear by around FY2021. The overall pictureof 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
FY 2021, the concrete targets for technical perspective are listed as follows:34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.

Clarify processing technology that could be expected to introduce 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 method to be developed byaround FY2021.

Clarify issues and measures concerning storage of solid waste until it is conditioned
It is described in the Mid-and-Long-term Roadmap that in accord with these efforts, specifications

and production methods of the waste packages associated with decommissioning work should bedetermined in the third phase. Then, a processing system should be installed in the Fukushima
Daiichi NPS. After establishing the prospects of disposal, production of waste packages should bestarted, and then carried out.
iii. Technical issues and plans for promoting sectoral strategies(1) Promotion of characterization and enhancement of analysis systems and technicalcapabilities
It is essential to analyze and understand a wide variety of radioactive waste generated in thedecommissioning process in order to consider reasonable storage and processing/disposal
methods. To carry out such analysis work, there are important issues, such as developing facilities
as hardware, development of human resources for analysis, and inheriting and enhancing technicalcapability on analysis. Therefore, for the time being, it is important to systematically promote thedevelopment of Radioactive Material Analysis and Research Facility and the development of
human resources for analysis. Through these efforts, technology, facilities and systems must be
established, and the necessary analytical work for decommissioning must be carried out
continuously and in a timely and appropriate manner.
Under the circumstance that the Laboratory-1 of the Radioactive Material Analysis and Research
Facility is scheduled to commence operation at the end of FY 2020; it is important, for the time
being, to improve the accuracy of models to obtain evaluation data based on the limited number ofradiological analysis data. Analysis for characterization has been studied, but in the future,35

clarification of analytical accuracy and review of the nuclides to be analyzed in accordance with theobjectives of storage and processing/disposal will be carried out, and simplification andacceleration of radiological analysis methods will be studied to establish an efficient analyticaltechnique.
In addition, by the government-led R&D program on Decommissioning and Contaminated Water
management, the sampling and analysis of rubble, contaminated water, secondary waste
generated by water treatment, etc. are carried out, and the correlation of nuclide composition ofeach analysis object is gradually clarified, and R&D for characterization are being carried out.
(2) Further safety improvement in storage
As temporary risk reduction measures concerning secondary waste generated by water
treatment, processes to be dehydrated for stabilization and extracted/removed the waste will be
implemented to transfer from temporary storage facilities to storage facilities on a hill.
On the technologies for stabilization, immobilization and conditioning of the secondary waste
generated by water treatment, while addressing challenges for introducing actual equipment,
gathering and evaluation of data on technical requirements should be made. Processing
technology expected to be applicable for actual processing should be identified, and specificationof waste package should be determined, from the point of view whether it may contributes toestablish selection method for preceding processing method.
Regarding the methods of storing high radiation dose solid waste generated during fuel debris
retrieval, study should proceed on the items such as the way of sorting fuel debris/waste, the typeof waste, the evaluation of waste volume, and the flow of handling waste, and narrow down
candidate methods for storage. For storage and management, it is necessary to study measuresagainst hydrogen generation, and reasonable methods, such as application of vented containers
should be examined.
For other solid waste, study should proceed on generation of hydrogen during storage, together
with the timing and content for the case of requiring further measures to secure safety, and reflects
to the Storage Management Plan as needed.
(3) Development of processing/disposal concept and safety evaluation method
In order to select candidate technology as a preceding processing methods, it is necessary to
conduct safety assessment with the specifications of the waste package that is developed byrespective candidate technologies, as a target. For that reason, selecting reasonable and feasible
candidate technologies and developing safety assessment methods will be made by the end of FY
2021.
Solid waste from the Fukushima Daiichi NPS is characterized by a large amount of waste with awide variety of properties. Therefore, it is necessary to consider solidification performance,
detoxification performance, control of hydrogen generation, processing speed, volume reduction
performance, etc. when selecting processing technologies, based on the R&D status of each36technology. From this viewpoint, the R&D of low-temperature processing technology (cement
solidification, etc.) and high-temperature processing technology (vitrification, etc.) are currently
being carried out as concrete processing technologies in the Government-led R&D program on
Decommissioning and Contaminated Water Management.
Furthermore, in establishing the concept of disposal, it is necessary to consider issues such as
enlarging the capacity of disposal facilities, the acceptability of various types of waste, anduncertain risks, due to the fact that the waste from the Fukushima Daiichi NPS is large in quantity,
has various properties, and is characterized by large uncertainties. From this point of view, theapproach will be studied for the case using preceding overseas examples as reference.
(4) Other
As solid waste to be generated with fuel debris retrieval in future, structures such as core internals
and outside of reactors to be dismantled and removed, and secondary waste such as filters
generated during fuel debris retrieval related works are expected. It is necessary to proceed to
study on the storage method for the solid waste along with the study on the method of fuel debris
retrieval.
Technical issues and further plans described in this article is as shown in Fig. 8.

37

Fiscal Year

Milestones

2015

2016

2017

2018

2019

Compilation of basic concept ofprocessing/disposal

2020

2021

2022 and later

Clarification of technological prospects onprocessing/disposal method and its safety

1.Volume reduction of solid
waste

Carry-in control, reuse, recycling and volume reduction

2.Waste characterization(1) Analysis data acquisition,
Management, etc.

Sampling
Analysis and measurement forverification of waste for disposal
Development/establishment of methods
on verification of waste for disposal
Planning/updating analysis plan, conducting analysis, characterization, accumulation/evaluation/management of analysis data
Development of sampling technique etc. (Method of sampling high radiation dose samples)

Establishment of Database system(2) Improvement of analysis
capacity

Development of radioactive material analysis and research facilities
Human resource development for analysis personnel(3) Improvement inefficiency of waste
characterization

Development of characterization method with complimentarily use of data evaluated from nuclide migration model

Optimization of the number of analytical samples, review of nuclides to be analyzed, simplified and speed-up
analysis methods, etc.

3. Storage(1) Storage Management
Plan(2) Study and evaluation ofStorage method

Storage
Development and review of the Storage Management Plan
Study on Storage measures of secondary waste from water treatment

Study on safety
improvement
measures(3) Study and evaluation of
Study on storage method, storage containers, and the way of putting waste into container

storage methods of solid
waste generated during
fuel debris retrieval

4. Development ofprocessing/disposal
concept and safetyassessment method

Establishment of a selection system of preceding
procesingUse of a
selectedsystemSurvey and setting of disposal method based on characteristics of solid waste

Survey and development of safety assessment method for each disposal method
Survey on conditioning
techniques

Technical development of processing methods related to stabilization and immobilization

Compilation of basic conceptof processing/disposal

Clarification of technological prospects onprocessing/disposal method and its safety

Study of processing/disposal

Fig.8 Key technical issues and further plans on waste management (Process chart)

383) Contaminated water managementi.

Sectoral target(1) Under the three basic principles concerning contaminated water issues (“Removing”
contamination sources, “Redirecting” fresh water from contamination sources, and “Retaining”
contaminated water from leakage), the reinforcement and optimum operation of the water level
control system should be continued. The multilayered measures should be implemented tocomplete the processing the stagnant water in the buildings by 2020.
(2) Considering the total decommissioning process including the full-scale fuel debris retrieval
beginning in near future, the long term strategy should be examined for the measures of thecontaminated water.
ii.

Sectoral strategies(1) Concept of risk reduction in contaminated water management
Measures have been taken based on the three principles on the issue of contaminated water(“Removing” contamination sources, “Redirecting” fresh water from contamination sources, and“Retaining” contaminated water from leakage).
The stagnant water in the buildings is the liquid containing a considerable amount of dissolved
radioactive materials and its hazard potential is relatively high. Thus the stagnant water is required
to be dealt with as soon as possible.
The radioactive materials contained in stagnant water have been treated with cesium adsorption
apparatus and transferred to the secondary waste such as adsorption vessel.
(2) Steady execution of contaminated water management indicated in the Mid-and-Longterm Roadmap
From a situation requiring urgent countermeasures immediately after the accident, it is thoughtthat it has shifted to a certain stable state where it is possible to forecast a mid-to-long-term plan
to some extent by preventive and multilayered countermeasures based on the three principles on
the issue of contaminated water. The milestones shown in the Mid-and-Long-term Roadmap are
as follows: (1) reduction of the contaminated water generation to about 150 m3/day (by 2020), (2)storing all the water treated by nuclides removal equipment in the welded type tanks (FY 2018), (3)by lowering the level of stagnant water in the buildings, separation of the penetrations between
Units 1 and 2 and between Units 3 and 4, respectively (by 2018), (4) reduction of the radioactive
materials in the stagnant water in the buildings up to approximately one tenth of the amount at theend of FY 2014 (FY 2018), and (5) completion of the treatment of stagnant water in the buildings(by of 2020).
As of July 2019, (2) and (3) of these have been completed. The amount of radioactive material
has been treated more than planned, on the other hand, due to the progress in the processing of
stagnant water, a high radioactivity concentration was detected in some areas, making it difficult to39

evaluate (4). However, efforts will be made to complete the treatment of stagnant water in buildings
by the end of 2020. It is expected that the specific measures outlined in the Mid-and-Long-term
Roadmap will continue to be steadily implemented to achieve the milestones.
(3) Study on contaminated water management based on the relation with fuel debris
retrieval work
Because full-scale decommissioning work including fuel debris retrieval will start after a while, itis necessary to discuss the optimal control of contaminated water and groundwater together at
each stage of the decommissioning process.
According to the target process of the Mid-and-Long-term Roadmap, it is considered that theprocessing of stagnant water in the buildings other than the reactor buildings of Units 1 to 3 will becompleted by 2020. By that time, a circulation system in which the stagnant water is recovered in
the reactor buildings (instead of turbine buildings) and purified to be used as a coolant should beestablished. In addition, examinations should be made on the lowering of the stagnant water levelin the reactor building and the lowering of the water level in the suppression chamber. Furthermore,
the PCV circulation cooling system is being studied in accordance with the expansion of the scaleof fuel debris retrieval work.
From the viewpoint to secure a multiple boundary, the water sealing method by repairing thebottom of PCVs have also been studied. It has been revealed, however, that complete water sealing
through the repair work of the bottom of PCVs is very difficult, hence the circulation system should
be prepared for the inflow of α-particles from inside of the PCVs to the stagnant water in the reactor
building. It is also necessary to consider setting an appropriate difference in the water level between
the stagnant water in the reactor building and groundwater, in case cooling water leaks from a PCV
into the reactor building.
As the fuel debris retrieval proceeds, when water injection for cooling the fuel debris is no longer
necessary, it can be expected that there is no water inflow into the reactor building. In such a case,
it is important to build a system that can stably control the groundwater level for a long period, suchas by combining passive equipment with fewer machine troubles than other to dynamic equipment.
iii. Technical issues for plans for promoting sectoral strategies(1) Steady execution of contaminated water management stated in the Mid-and-Long-term
Roadmap
By steadily continuing preventive and multilayered measures based on the three principles on
the issue of contaminated water, consideration should be made toward the completion of treatmentof the stagnant water in buildings, while suppressing further generation of contaminated water andpreventing leakage.

40

(2) Study on contaminated water management based on the relation with fuel debris
retrieval work
With regard to the PCV circulation cooling system during fuel debris retrieval work, since fueldebris-derived materials containing α-particles may be mixed into the water treatment system, it isnecessary to proceed with the examination of the entire system, including enhancement of themonitoring to confirm the concentration of radioactive materials at the inlet of the water treatment
system and the installation of equipment to reduce the concentration of radioactive materials.
In addition, for the PCV circulation cooling system which is to be established depending on the
expansion of the scale of fuel debris retrieval, it is necessary to set the conditions for receiving apart of purified water at existing equipment as a destination of water constantly flowing into thereactor building, in parallel with examining the PCV circulation cooling system.
In order to maintain the effectiveness of contaminated water management for the future, further
enhancement is needed on monitoring system (e.g. observation point, observation frequency ordata management, and so forth) for water level of groundwater and radioactive materials for the
purpose of steadily managing the groundwater surrounding the buildings as well as implementing
regular inspections and updates of facilities for sure. Moreover, necessary contaminated water
management should be considered based on the association with risks from large-scale natural
disasters including tsunami or heavy rain and further decommissioning operations.
Technical issues and further plans described in this article is as shown in Fig. 9.
Fiscal Year

2019

2020
2021
Reduction of the contaminated water
generation to about 150 m3/day

2022

2023

On-site work
Technical studies for on-site construction ineach item

Milestone
Completion of the treatment of
stagnant water in the buildings

REMOVING contamination sources
Maintain additional effective
radiation dose at the site boundaries
at a level below 1 mSv/year

REDIRECTING fresh water fromcontamination sources

Treatment with purification Systems
Reducing the total amount of contaminated water to about 150 m3 per day

Controle by groundwater by-pass, subdrainage and land-side impermeable walls

Reduce the contaminated water
generation to about 150 m3/day by
average rainfall

Paving the site, Removal of rubble fromthe roof, Waterproofing

RETAINING contaminated water fromleakage

Securing Tank capacity

To be responded properly according to generation of contaminated water, etc.

Ground stabilization, Maintenance of land-side impernmeable wall , Monitoring of groundwater/inside harbor

Completion of stagnant
water in the buildings

Treatment for the stagnant water inthe buildings

Contaminated water management
based on the relationship with fueldebris retrieval

Lowering the level of groundwater/ stagnant water in the building

Determination of fuel debris retrieval
methods for the first implementing unit

Maintaining exposed condition of thefloor line for turbine buildings

Start of fuel debris retrieval at
the first implementing unit
Taking required actions in accordancewith the phase of fuel debris retrival

Study for consistency between existing circulation cooling system
and PCV circulation cooling systems and monitoring method

Fig.9 Key technical issues and further planning on contaminated water management(Process chart)

414) Fuel removal from spent fuel poolsi.

Sectoral target(1) Risk assessment and management for the progress of the work will be carried out properly,
and measures for safety and security including the prevention of scattering of radioactive
materials will be taken thoroughly. For Units 1 and 2, the removal of fuel in SFP will start by2023. For Unit 3, the removal is scheduled to be completed in FY2020.
(2) By transferring the fuel stored in the common spent fuel storage pool to the dry cask temporary
custody facility, the fuel in the spent fuel pools of Units 1 to 4 is to be stored in the common
spent fuel storage pool appropriately.
(3) Based on the assessment of the long-term integrity and investigation for future treatment of
the removed fuel, the storage and future treatment methods of them will be fixed around 2020.
ii.

Sectoral strategies(1) Risk reduction concept and concrete plan for removing fuel in SFP
The fuel stored in SFP of the reactor buildings of Units 1 to 3, some of which were partiallydamaged by the hydrogen explosion, is to be transferred to the common spent fuel storage poolthat needs lower safety management, as shown in Fig. 3 of Chapter 2, in accordance with anappropriate and concrete work plan developed depending on the situation of each unit, as soon as
possible. Especially, return of the local residence and reconstruction approaches began after the
first evacuation instruction has released in the locating municipalities of Fukushima Daiichi NPS in
April 2019. Considering these circumstances, careful approaches focusing on safety more arenecessary against dust dispersion, and the like. For example, in Unit 1, since there is rubble on theoperating floor, and there are operational risks such as a rubble falling into the spent fuel pool
during the rubble removal work or impact on surrounding area and workers resulting from dust
scattering. While giving due considerations to those, it is necessary to carefully prepare for theremoval of fuel in SFP.
Work schedule for Units 1 to 3 was specified in the Mid-and-Long-term Roadmap, and TEPCO
has been proceeding with their tasks to meet this schedule.
In Unit 1, roof slab, steel frame building materials for the upper part of the buildings, and fuelhandling machines were scattered around the operating floor. The removal work of this rubble
started in 2018 and has been continuing, and the removal of fuel from the SFP is scheduled to startin FY 2023.
In Unit 2, in order to install the fuel removal facility, a method to access the operating floor isbeing considered, and removal is scheduled to start around FY 2023 based on the radiation dose
survey conducted on the operating floor in FY2018.

42

In Unit 3, removal of fuel in SFP began in April 2019 and to be addressed with top priority given
to safety assurance while aiming to finish in FY2020, although there were some delays due to anumber of malfunctions that occurred during the test runs of the fuel handling equipment.
The fuel in SFP of Units 5 and 6 reactor buildings are being stored under stable conditions sameas a normal nuclear power plant. The Mid-and-Long-term Roadmap states that the spent fuel ofUnits 5 and 6 should be properly stored in each spent fuel pool for the time being and then, theremoval should be carried out so as not to affect the operations of Units 1 to 3.
(2) Storage plan for removed fuelAdequate storage capacity for the removed fuel in SFP of each should be reserved both in thecommon spent fuel storage pool and in dry cask temporary custody facility. For this reason, it isnecessary to expand storage capacity of the dry cask temporary custody facility systematically.
(3) Decision of future treatment and storage methods
The fuel in SFP includes many kind of spent fuel such as flawless spent fuel, damaged one
before the accident, and that may be damaged by the fallen rubbles into the spent fuel pool. There
was also a history of seawater injection into the spent fuel pools of Units 2, 3 and 4 when theaccident occurred. Although these effects are expected to be small, it is necessary to identify
whether there are technical requirements that may impede the same treatment as ordinary spentfuel.
In the future, considering the status of fuel removed from Unit 3, assessment of the long-term
integrity and investigation for future treatment of the removed fuel will be carried out and, future
treatment and storage methods will be decided around FY 2020.
iii. Technical issues and future plans for promoting sectoral(1) Removal of fuel in SFP<Unit 1>In Unit 1, the roof of the building collapsed due to hydrogen explosion accumulated on theoperating floor as rubbles and the fuel handling machine (FHM) and the overhead crane were
deformed and damaged and covered over the spent fuel pool. When removing this rubble, it isimportant to take measures to prevent rubbles, FHM or overhead crane from falling into the spent
fuel pool, and it is necessary to carefully conduct the required work over a certain period of time,
including the protection of the spent fuel pool and the support of overhead cranes. In addition,with the progress of the rubble removal work, it is considered that the status of the site, such as
the distribution of rubble, will be revealed. Therefore, it is necessary to make steady progress inthe work step by step based on the onsite information.
In addition, from the viewpoint of effects on the surrounding environment, removal of rubble on
the operating floor and manipulation of the well plugs need to be carried out with measures such43

as the prevention of radioactive dust dispersion and radiation dose monitoring, due to possible
effect of sky-shine radiation caused by a gap of well plugs.
<Unit 2>In Unit 2, so far both plans have been studied, which are to share containers for fuel removalfrom SFP with containers for fuel debris retrieval and to install a cover for fuel removal from SFP
respectively for the purpose of dismantling the upper part of the operating floor in the reactor
building. In addition to this, another plan has also been studied, which includes a method to
reduce risk of radioactive dust dispersion during dismantlement of the buildings and to accessfrom the south side of the reactor building without dismantling the upper part of the operating
floor as much as possible from viewpoints of advancing construction in a safer and more securemanner.
In regard to determination of removal plan for fuel in SFP, it is necessary to comprehensively
study radioactive dust dispersion control, securing safety for surrounding environment andworkers’ radiation exposure, rainwater control and feasibility with other works to be performed inparallel.
<Unit 3>
In Unit 3, there was a malfunction with the fuel removal device, the start of the removal was
significantly delayed from the original plan. Of fuel in SFP, and twenty-eight new fuel were removed
from the pool in April 2019, completing the transfer to the common spent fuel storage pool. It isnecessary to continue working steadily toward completing the removal of the remaining fuel in SFP
in FY2020.
(2) Proper storage of removed fuelFor systematic transportation of fuel in SFP possessed by the entire site to the common spent
fuel storage pool, a fuel transportation plan needs to be developed, taking the fuel stored in Units
5 and 6 into account as well, and dry cask temporary custody facility needs to be added accordingly.
(3) Decision of future treatment/storage method
R&D on the long-term integrity of the fuel in SFP which has contacted with seawater or fallen
rubble has indicated that removed fuel can be stored safely under the environment of common
spent fuel storage pool for a long period. Also, it was confirmed that the effect of seawater andscratches by fallen rubble on the fuel is limited for integrity of stored fuel in the dry cask.
Furthermore, another R&D showed a perspective that the impact of seawater and scratches byfallen rubble on the fuel is very limited on the treatment of the fuel removed from SFP.
In the future, it is necessary to check the fuel removed from Unit 3 and determine whether or not
it needs to be considered for long-term storage.
Technical issues and future plans described in this article is summarized in Fig. 10.

44

Fiscal Year

2019

2020

2021

2022

Milestone
Unit 1
Unit 2

2023

2024

2025

Start of fuel removal from Unit 1 (by FY2023)
Start of fuel removal from Unit 2 (by FY2023)

Cover installation, etc.

Rubble removal, etc.
Investigation ofoperating floor, etc.

Fuel removal

Dismantlement and modificationof upper part of the building, etc.

Fuel removal
Construction, etc.

(Selection of retrieval
plan for Unit 2)
Unit 3

Selection and examination
Submit/Approval request to
implementation plan/Preparation work

Fuel removal
On-site work

Disassembly of upper part of
exhaust stack for Units 1/2

Surrounding environment

Proper storage ofremoved fuelTechnical studies for on-site constructionin each item

Measures to preventsea contamination, etc

Procurement of dry cask
Transfer of dry casks from the common spent fuel storage poolto the dry cask temporary custody facility

Fuel removal from Units 5 and 6
Implemented to the extent not affectthe operations on Units 1 to 3
Installation of additional dry cask temporary custody facility

Determination of future treatment and storing
method of removed spent fuel (around FY 2020)

Study on future
treatment and storage
methods

Study on long-term integrity inconsideration of fuel of Unit 3
Study on treatment and storing methods

Fig.10 Technical issues and further plan on removing fuel from spent fuel pool (Process chart)

455) Other specific measuresi.

Sustaining of reactor cold shutdown status
As for the plant conditions of Units 1 to 3, it is judged that a stable state of cold shutdown ismaintained based on the internal plant data on PCVs, such as radiation dose, temperature,hydrogen concentration, pressure, radioactive substance concentration, etc. To maintain the stablestate in the future, it should be continued to monitor parameters in PCVs and seal nitrogen to
reduce a risk of a hydrogen explosion, while maintaining and improving reliability throughmaintenance and management. In light of the fact that the decay heat of fuel debris is thought tohave decreased significantly, a flow rate reduction test for fuel debris cooling at Unit 2 wasconducted in April 2019, and a temporary shutdown test for cooling was conducted in May. With
this, the actual condition of the cooling condition of fuel debris is grasped, and improvements suchas the optimization of the emergency response procedures are expected to be made.
ii.

Radiation dose reduction and contamination expansion prevention all over the power
station(1) Prevention of sea contamination expansion
The concentration of radioactive materials in the port is below the concentration limit defined in
the notification because of the removal of highly concentrated contaminated water in the trench,
installation of the sea-side impermeable wall, covering of the seabed soil, etc. Measures to reducethe concentration of radioactive materials in the drainage channels that flow into the port, including
measures to manage rainwater flowing in from the rooftops of buildings and paving around thebuildings, should be continued.
Regarding contamination of the soil in the vicinity of the harbor, assessing the impact on theocean from a long-term perspective and future environmental restoration, R&D should be
conducted such as to clarify the near-surface nuclide migration mechanism and refine the analyticalmodels.
(2) Management of gas and liquid waste
Monitoring of gas and liquid waste should be continued and its emission should be closely
controlled to ensure that the concentration limits defined in the Notification is strictly observed. With
this view, proper countermeasures should be taken as their concentrations are made as low as
possible based on a reasonable methods.
(3) Radiation dose reduction through site decontamination
In March 2014, TEPCO formulated “Implementation Policy of Radiation Dose Reduction on the
Site of the Fukushima Daiichi NPS" and set target radiation dose rates in stages for each area inthe sites to reduce the radiation dose. As a result of these efforts, the target radiation dose
equivalent rate of 5 μSv/h was achieved at the end of FY 2015 in the area where lots of workers

46

work, except for the zones surrounding Units 1 to 4 and the waste storage area. The areas where
working in general work clothes is permitted have currently increased to approx.96% of the entire
site. The average radiation dose equivalent rate should be maintained below 5 μSv/h, and thetarget radiation dose equivalent rate should be gradually lowered to bring it as close as possible tothe state before the accident.
(4) Reduction of environmental impact
Regarding the evaluation of the radiation dose at the site boundary including additional emissions
from the entire site, the value to less than 1 mSv/year is continued to maintain after the goal toreduce the value to less than 1 mSv/year has been achieved at the end of 2015 in the result of theefforts stated in the previous clauses and purification of highly contaminated water.
(5) Comprehensive risk review
TEPCO conducted a comprehensive inspection of risk sources that may affect the outside of thesite and announced it in April 2015. In addition, for the radiation sources requiring additional
measures, specific measures were discussed while taking priorities into consideration. They werereviewed as appropriate reflecting environmental changes, and have been explained andannounced at places such as the local adjustment meeting for decommissioning and contaminatedwater management.
Also, the Nuclear Regulation Authority created a target map for reducing the mid-term risk of the
Fukushima Daiichi NPS in February 2015. This target map for reducing the mid-term risk ofFukushima Daiichi NPS, which has been updated from time to time, is characterized by a risk
reduction work process of about three years, while focusing on the presentation of residual risk. In
regard to this, TEPCO reported the current approach, issues and responding status according to
the further schedule in May 2018.
It is important to continue to reduce and comprehensively grasp the risk sources like this, while
taking the positioning and priority in the entire decommissioning project into consideration for
implementing each measure.
iii. Plan for decommissioning measures for nuclear reactor facilities
In the Mid-and-Long-term Roadmap, TEPCO should formulate a decommissioning plan of the
Fukushima Daiichi NPS in phase 3 after commencing fuel debris retrieval work, after starting debris
retrieval operations. NDF should provide multifaceted and expert advice and guidance based on
the progress and forecast of the decommissioning, the situation of the reactor buildings, and thetrends of R&D with wisdom and knowledge from around the world.
Based on the need to take prompt and efficient measures for reducing risks of the whole facility
in Fukushima Daiichi NPS, NRA is examining a review to regulate entire Fukushima Daiichi NPS
integrally mainly with the implementation plan, in order to put more effective regulation to47

decommissioning work into practice. Therefore, the provisions of “Plan for decommissioning
measures” are not to apply to Fukushima Daiichi NPS.
iv. Concrete efforts toward securing safety(1) Efforts to ensure work safety
For the work plans that require workers to intervene in a high radiation dose environment, it isimportant to evaluate the environment according to input resources from the viewpoint of"justification and optimization", aiming to ensure the safety of the working environment as well as
suppressing personal radiation dose. Particularly when the work is “for the first time,” “changed,”or “for the first time in a long time,” it is essential to fully implement work training using a mockup
in order to develop, implement and verify effective work procedures and test methods.
Moreover, it is necessary to formulate a detailed work plan for each work step, to take preventive
measures concerning troubles that may occur, and to consider ways to cope with unexpected
situations.
In line with the Mid-and-Long-term Roadmap, it is stated that measures for industrial accident
prevention will be taken and reviewed continuously, medical preparedness will be planned in
anticipation of industrial accidents, and measures will be taken to reduce occupational risk ofradiation exposure as much as possible. It is important to ensure a perfect system of work safety
by continuing these efforts.
(2) Efforts for facility safety
In the Fukushima Daiichi NPS where there are various kinds of work and safety facilities, special
attention to the safety of facilities is also essential. For this reason, measures are implemented tomaintain and improve equipment reliability based on the maintenance plan for every piece ofequipment. Particularly, for equipment vital to securing safety for cooling fuel debris, it is important
to continue thorough measures that will be taken to prevent their important function from stopping,
not just from the standpoint of equipment but from management and operation standpoints as well.
In the last fiscal year, there was a malfunction with the fuel removal device when fuel was
removed from Unit 3 SFP. As a result, the start of the removal was significantly delayed from theoriginal plan. This malfunction was directly caused by insufficient quality control of products
procured from overseas. Therefore, TEPCO is taking measures to strengthen quality control toprevent recurrence.
While this response is of course necessary, we believe that this case should not be viewed asmerely a matter of quality control, but rather as an indication of the existence of an organizational
problem, i.e., a lack of broad technical response skills necessary to promote the project.
Considering that more difficult work such as fuel debris retrieval is expected in the future, this caseshould be utilized in order to strengthen technical response skills as a decommissioning
organization in the future.

48

(3) Security enhancement
A great quantity of nuclear fuel material is stored in the Fukushima Daiichi NPS. Accordingly, it
requires particular attention to be paid for its security same as a normal nuclear plant, measures toconfirm the reliability of each individual, enhance nuclear security training, prevent unauthorized
intrusion into the sites, etc. are being implemented. Continuing with these efforts, it is necessary to
implement appropriate measures for operation to allow accepting the visits of inspectors.

496) Comprehensive efforts for the decommissioning project of the Fukushima
Daiichi NPS
In the decommissioning project of the Fukushima Daiichi NPS in the future, more complex andgreatly uncertain challenges, such as fuel debris retrieval, must be coped with over a long term.
For this reason, it is necessary to make efforts to solve problems in a systematic manner whilelooking ahead and ensuring a lead time for making sufficient preparations.
Decommissioning of the Fukushima Daiichi NPS is a complex and multi-layered large-scale
project, various efforts are carried out concurrently and in parallel and in a mutually related manner.
In particular, when fuel debris retrieval is started in the future, the relevance of the work in various
fields such as the treatment of cooling water used for cooling debris, the installation of debris
storage facilities, and the sharing of space with various other works will be strengthened. To
proceed with the overall decommissioning project in a stable manner over the mid- to long-term, it
is important to optimize the allocation of limited resources (people, goods, money, time, and space)
while ensuring the consistency and feasibility of these many related efforts as a whole.
From the viewpoint of the necessity of the systematic work with a forward-looking perspective
and the necessity of coordinating the complicatedly related work as a whole, in order to proceedwith the decommissioning project steadily and efficiently in the future, it is necessary to formulate
a consistent long-term plan for entire decommissioning from the current state to the short-, mid-tolong-term, so that various efforts can be managed comprehensively in accordance with this plan.
Even if a long-term plan is drawn up, it is virtually impossible to develop a plan into the future withhigh accuracy at this point because there are still significant uncertainties in the status ofdecommissioning and the work to be required in the distant future. Therefore, as a long-term plan,
it is considered to be practical to optimize the work plan for the time being within the long-term
range as long as possible where the work can be embodied to a certain extent, from the viewpointof showing the path of decommissioning inside and outside, though there are restrictions in termsof how much detail the embodiment can be made.
As to the decommissioning of the Fukushima Daiichi NPS, we do not have any previous
experience, and it is a project that needs to be carried out in a severe environment and with limited
information, while accumulating experiences and results. To safely and stably proceed with adecommissioning project, it is important to draw up a plan based on the information currently
obtained and assumptions, to incorporate new information and various knowledge gained as work
progresses in a timely manner, and to review the plan flexibly according to the situation that
becomes clear. It should also be noted that over-adherence to a plan after it has been developed
may reduce the scope for selecting an optimum or a safest approach under the situation, thereby
impeding the progress of safe and steady work.
For such a concrete use of the long-term plan, it is more important to set judgment points inadvance at an appropriate time so that new knowledge can be obtained, evaluate the progress of50

work at that time and knowledge, consider how to proceed thereafter, and flexibly revise andoperate the long-term plan based on that.

51

4 Handling critical enablers for smooth operation of the project1) Actions toward improvement of working environment and conditions
The working environment of the Fukushima Daiichi NPS has now been steadily improved. A goodworking environment is the basis for ensuring safe and steady progress of the decommissioning
project of the NPS, which will be carried out over the long term. For example, TEPCO is improving
the working environment infrastructure by consolidating and removing existing rest stations andsetting up alternative rest stations, etc. Moreover, a variety of measures are taken such as
management for safety and sanitation, preventing heatstroke, radiation exposure management andradiation dose reduction measures in the site.
It is necessary, in the future, to make appropriate and ongoing efforts to improve the working
environment and working conditions.

2) Enforced

management

structureforsteadymid-and-long-term

decommissioning
Since the Fukushima Daiichi D&D Engineering Company was established, TEPCO has put inplace a project framework for decommissioning. However, there is a challenge that responsibility
and authority are not apparent; for example, line operation management and project operation
coexist in actual management. To clarify the responsibilities and the authority for project toward
FY2020 and to support overall optimization of project management, TEPCO has established a
Program Management Office (PMO) made efforts to strengthen project management. NDF has
also established a Program Supervision and Support Office to supervise and support TEPCO'sefforts. In addition, it is necessary to strengthen the management mechanism for the long-term
decommissioning project, deepen the technical understanding of the individual works actually
carried out in the project, and make this mechanism function effectively under the appropriate work
management.

3) Developing and securing human resourcesi.

Developing and securing operators and engineers
The decommissioning project of the Fukushima Daiichi NPS requires completely different skills

from the technologies related to the construction and operation of NPSs that TEPCO has
accumulated to date as well. Accordingly, a draft technology map has been developed to grasp theoverview of necessary technologies and decommissioning personnel, and this map is expected tobe utilized for developing and securing human resources in the future. In addition, NDF is preparing
to provide opportunities for engineers and others working at the Fukushima Daiichi NPS to learncommon technologies required for decommissioning work.
In handling a complex large-scale project like the decommissioning of the Fukushima Daiichi
NPS that involves many related factors , it requires specialized personnel with the ability to manage

52

projects from a comprehensive perspective, including the consideration of the relationship between
the projects based on the overview of the entire decommissioning process.
ii.

Fostering the next generation to play roles the decommissioning of the Fukushima
Daiichi NPS in the future
To continue decommissioning of the Fukushima Daiichi NPS as well as research anddevelopment activities for a long period of time in a sustainable manner, it is essential to train andsecure future researchers and engineers. For this purpose, it is important for industrial-academicgovernmental institutions relating to nuclear power, as a whole, to steadily promote making efforts.
Specifically, the industry and educational institutions should cooperatively continue the activities
to enhance students' understanding of the nuclear power industry and show the attractiveness of
the industry. They should also convey to students that the decommissioning of the Fukushima
Daiichi NPS is an extreme technological challenge unprecedented in the world, as well as building
and showing a variety of career paths for researchers and engineers to take part.
In addition, the stable development of researchers and engineers is of paramount importance.
From this perspective as well, the Ministry of Education, Culture, Sports, Science and Technology(MEXT)’s the Center of World Intelligence Project for Nuclear S&T and Human Resource
Development (hereinafter referred to as “the World Intelligence Project”) has started in 2015. It
develops framework of common core nuclear research program designed to foster young peopleat universities and colleges especially since FY 2018. It is also essential, in the future, to encourage
and enhance the measures aiming to secure human resources among universities and colleges.
Furthermore, in long-term and large-scale projects such as the Fukushima Daiichi NPS
decommissioning, it is essential to develop core personnel for research and development who can
perform scientific and engineering investigations from an academic perspective and personnel witha panoramic perspective (system integrators) who can integrate individual technology seeds into asystem with practical functionality. This activity is being implemented by Essential R&D themes
described later in Chapter 5.

53

5 R&D Initiatives
1) Basic policy for R&D
i.

Basic policy
NDF has developed an R&D duties implementation policy based on the NDF Act, and has been

managing a wide range of R&D to support the steady implementation of initiatives technicallyaccording to the Mid-and-Long-term Roadmap.
As detailed processes towards the decommissioning will be clarified, the roles of each R&D
player should be more clarified. In doing so, it is necessary for the government and business
operators to appropriately divide their roles and steadily promote the application of research anddevelopment outcomes to the work front. As the progress of engineering is expected to lead to theextraction of R&D tasks for on-site application, TEPCO is required to make efforts to put moreweights on their own technological development that are directly linked to applicability on site formaterializing decommissioning work.
ii.

Entire perspective of R&D
Various problems exist in the decommissioning of the Fukushima Daiichi NPS, and R&D activities

for solving these problems are being conducted by a variety of industrial-academic-governmental
institutions engaged with the Fukushima Daiichi NPS decommissioning R&D project through theareas of basic/fundamental research, applied research, and development/utilization Fig.11. Toorganically link these activities and efficiently solve the on-site problems through R&D, NDF
regularly holds meetings of “the Decommissioning R&D Partnership Council” according to thedecisions made by the Team for Countermeasures for Decommissioning and Contaminated Water
Management.

54

METI

MEXT

The Government-led R&D※８

SupportSupport

Program on Decommissioning
and Contaminated Water
Management

Center of World Intelligence
Project for Nuclear S&T and
Human Resource Development※９

Cooperation

Management
Expenses Grant
Funding※７

Assignment

Sector of Fukushima R&D

Fund Establishment Organization

Decommissioning Strategy Committee

SupportProject
Management Office(Member） NDF,JAEA,TEPCO, IRID, Plant Makers,
Related Experts, METI, MEXT

Cooperation

Decommissioning※１
R&D Partnership Council

Assignment

Foreign
Governmental
Agencies

Project
Management
OfficeCLADSFund for Decommissioning andContaminated Water Management

Funding

Funding

JAEA

NDF

Naraha Center for Remote
Control Technology
Development

Contract/
collaborative
Research

Okuma Analysis andResearch Center

Cooperative
relationship※６

Fukushima Environmental
Safety Center

Administering
Administering

Request for study and Support

Commissioned Research Institutes

TEPCO

Platform of Basic
Research for
Decommissioning
Participation

Commission

Exchange of researchneeds/seeds

IRID
National R&D Agency
Plant makers
Electric power Companies, etc.

Domestic / Foreign Enterprises※１※２

Project
Management
Operation

Information
sharing

Subsidized Project Operating Entities

Other
makers, etc.
(including
foreignenterprises)

Sharing/planning
R&D information

Human Resource
Development andResearch
Program for
Decommissioningof
Fukushima
Daiichi NPS
Adopteduniversities, etc.

Domestic
universities,
Research
institutes, etc.

Acceleration
Program for
Reactor
Decommission
ing
Adopteduniversities,
etc.

Foreign
Universities/
Research
Institutes
Joint
Research

Decommissioning R&D Partnership was established in NDF according to a decision of Team for Countermeasures for Decommissioning and Contaminated Water Treatment.
Bold solid arrows mean supplies of R&D and management expenses (except for facilities expense).Light solid arrow means cooperation. Dotted line arrow means participation in
Decommissioning R&D Partnership Council.
※３ Some institutions including JAEA are at the multiple positions.
※４ Each institution has their own cooperation with foreign institution based on MOU, etc.
※５ R&D activities by other institutions including Central Research Institute of Electric Power Industry are abbreviated.
※６ Among the promotion projects of nuclear energy science technology/human resource development that require collective know-how, the adopted projects up to 2017
were entrusted by MEXT to the trustee, which are not shown in this figure.
※７ Subsidies for the promotion projects of nuclear energy science technology/human resource development that require collective know-how are delivered to JAEA, but expressed
as being delivered to CLADS for the sake of clarity here.
※８ For Decommissioning and Contaminated water treatment subsidy project, NDF drafts the next R&D plan and METI determines it based on the policies on Roadmap and the Strategic Plan and R&D progress.
※９ NDF participates in the steering committee of human resource development promotion project of Nuclear Science Technology that gathers wisdom and intelligence, as a constituent.

Fig.11 Whole picture of R&D structure of the decommissioning of Fukushima Daiichi NPS(As of FY 2019)2) R&D of decommissioning required for on-site work/engineeringi.

Promotion of effective research and development
There are two types of R&D activities towards practical use for successfully implementing thedecommissioning of the Fukushima Daiichi NPS: the engineering activities including technologicaldevelopment implemented by TEPCO and the Government-led R&D program on Decommissioning
and Contaminated Water Management carried out by selected subsidiary companies. In particular,
management of R&D is required to be carried out in a project-base manner in the future. In otherwords, R&D tasks that have been deemed necessary through engineering studies should be
carried out in a timely and accurate manner by appropriate implementing institutions, and theresults should be provided to the work front timely and accurately. To this end, TEPCO and NDF
should organize the details of R&D currently in progress, and R&D tasks required in the future
under the project management system in relation to the engineering schedule, that is, clarifying
when the problem must be solved and which project needs it.
In this regard, the implementation of R&D tasks, including implementing the tasks in the
Government-led R&D Program, should be considered in line with the basic concept of an
appropriate division of roles between the government and TEPCO according to the details of thetasks. Specifically, R&D activities that require government support are deemed highly difficult, andin this regard, TEPCO is required to carry out R&D tasks that have many engineering elements.

55Based on this concept, TEPCO is required to: (1) position necessary R&D tasks in theengineering schedule, including the Government-led R&D Program; (2) actively commit to the
management of overall processes in this Government-led R&D Program, mainly in the stage
leading to engineering by TEPCO; and (3) extract R&D tasks from engineering studies and steadily
advance research and development.
ii.

Future approach to research and development
As a result of the research and development conducted through the Government-led R&D

Program, there has been certain accomplishments such as the situation of the inside of PCVs havebeen clarified by degrees, by implementing elemental technology development and developing
research devices. As mentioned above, as the concrete process for full-blown decommissioning
has become clearer, the research and development directly related to the on-site application torealize decommissioning work will be required in the future. For this purpose, TEPCO, while
performing actual work on site, shall plan out and manage R&D, based on their own operations
and measures for securing safety, as well as the overall picture of decommissioning. Accordingly,
TEPCO needs to make efforts to put more weights on the research and development directly
related to on-site application to effectively conduct, while establishing a system as own planningand management of research and development. As mentioned above, regarding R&D activities
including fundamental ones, the governmental support should be provided, which require an
approach on a mid- to long-term basis with high degree of technical difficulty and thus, are difficult
for TEPCO to implement and the government should support.

3) Enhancement of basic study and R&D infrastructure for the success of thedecommissioning projecti.

Essential R&D Themes and its strategic promotion derived from the needs
While universities and public research institutes in charge of basic research are expected tomaintain and develop human resources, knowledge, and infrastructure that can promptly respondto technical issues requiring science and engineering knowledge when they arise in the future, it isalso important for them to share their awareness for the issues that the decommissioning sites arefacing.
To facilitate the Fukushima Daiichi NPS decommissioning project in a safe, steady and effective
manner, it is essential to plan out mid- and long-term R&D strategies including scientific andtechnological studies based on understandings of the principles and the theories. For this purpose,
NDF has built a task force on research collaboration and specified the 6 Essential R&D Themesthat should be preferentially and strategically targeted based on the discussions at theDecommissioning R&D Partnership Council.

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ii.

Building R&D infrastructure based on mid-and-long-term vision
To make the decommissioning work proceed steadily in terms of technology, it is essential towork on developing R&D infrastructure and accumulating technological knowledge, developing
generic technologies and collecting basic data, including the Essential R&D Themes, building up
research centers, facilities and equipment, and human resource development.
The building for international research collaboration of JAEA/CLADS has opened in April 2017
in Tomioka-machi, Fukushima prefecture. According to a proposition by NDF, the Center of WorldIntelligence Project for Nuclear S&T and Human Resource Development by the Ministry of
Education, Culture, Sports, Science and Technology (MEXT) is implemented under the structure
centered on JAEA/CLADS from the newly adopted issues since FY2018.
It is also important to develop research infrastructure of hardware. JAEA put the Naraha Remote
Technology Development Center (Naraha-machi, Fukushima Prefecture) in service in April 2016,
Fukushima Prefectural Centre for Environmental Creation where Fukushima Prefecture, JAEA, andthe National Institute for Environmental Studies have their offices (Miharu-machi, Fukushima
Prefecture) opened in July 2016, and JAEA opened the facility management building of the Okuma
Analysis and Research Center (radioactive material analysis and research facility) (Okuma-machi,
Fukushima Prefecture) in march 2018. R&D infrastructures aiming at the mid-and-long-term vision
are being set up mainly in Fukushima Prefecture.

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6 Enhancement of international cooperation
1) Significance of international cooperation
In recent years, nuclear reactors and nuclear fuel cycle facilities, constructed in the development
age of nuclear power, are coming to the end of operating life and these decommissioning havealready been progressing in the world. There are three major nuclear reactors caused severe
accidents: Windscale Unit 1 in UK, Three Mile Island Unit 2 in the US, Chernobyl Unit 4 in Ukraine.
These facilities have taken stabilization and safety measures for a long time. Furthermore, there issignificant uncertainty in the management of various radioactive substances in past nuclear
facilities called “legacy sites” where are located in the UK, US and France etc. In these sites, there
are implemented decommissioning and environmental remediation for a long time. These countries
have continued to be challenging to issues such as technological difficulties called “unknown
unknowns” (don’t know what is unknown), project management over several decades, and securingof large amount of funds.
As a risk reduction strategy, it is important to learn the lessons of decommission experience from
accident reactors and legacy sites in the world and to utilize it into the actual decommissioning aswell as good use of excellent technologies and personnel resources that have been cultivated ineach countries, in order to make steady progress on decommissioning of the Fukushima Daiichi
NPS that engineering challenges are addressed. In addition, it is also important to engage inmutually beneficial decommissioning with open to international societies, while giving back to theknowledge and the like obtained from Fukushima Daiichi accident and decommissioning actively
and strategically through international cooperative activities on decommissioning, to maintain anddevelop continuous understanding and interest or cooperation of international communities on
decommissioning.
In regards to the international cooperation, it is important to utilize a multilateral cooperation
framework through the international institutions such as IAEA, Organization for Economic Cooperation and Development/Nuclear Energy Agency (hereinafter referred to as “OECD/NEA”), in
addition to proceed with bilateral cooperation in harmony with the circumstance in each country.
These international institutions have a role of contribution to designing the international standard,share the knowledge and experience among nations, and form the international common
perceptions for decommissioning. To proceed with the decommissioning of the Fukushima Daiichi
NPS in an open manner on the international basis, it is important to participate in the activities ofthese institutions. At the same time, Japan participates in the discussion for design the international
standard, based on the experience of the Fukushima Daiichi decommissioning, it leads to sharethe experience with memberships of the institutions. It is also expected to fulfill the responsibility to
the international society.

582) Facilitation of international cooperation activities
i.

Enhancement of partnership with overseas decommissioning agency
As the decommissioning of the Fukushima Daiichi NPS is delivered over a long period of time, itis necessary to establish a long-term and continuous partnership with overseas decommissioning
agencies.
Especially, the decommissioning of legacy sites will serve, as a model for approach preceding to
the Fukushima Daiichi NPS decommissioning, in many knowledge in accordance with technology
and management. Decommissioning for legacy sites is promoted by decommissioning institutions
that is established officially by each country because it requires the expertise, concept and newtechnologies, etc. that differ from the operation/maintenance for nuclear reactor or nuclear fuelcycle facility. Therefore, it is important for NDF to establish and reinforce a long-term partnershipwith these institutions such as Nuclear Decommissioning Authority (NDA), Commissariat a l’energie
atomique (CEA), United States Department of Energy, Office of Environmental Management(DOE/EM) under government-level framework. TEPCO should establish a long-term partnershipwith overseas decommissioning operators, and these should be broad cooperation-based.
ii.

Integrating and utilizing wisdom and knowledge from around the world
In regard to decommissioning of the Fukushima Daiichi NPS, wisdom and knowledge fromaround the world that our country should obtain are implemented with a variety of approaches suchas system/policy, providing strategy, project plan/operation, ensuring security, regional
communications, and so forth, not only in technical aspect but operational aspect. On the other
hand, there are tendencies to support decommissioning of the Fukushima Daiichi NPS byinternational society, and several kinds of supports have been given by overseas governmental
institutions and experts including DAROD project led by IAEA and collaboration projects promoted
by OECD/NEA.
Decommissioning is implemented by many companies and decommissioning operators under
the contract in both domestically and internationally. The decommissioning market is expanding
worldwide. In order to use the excellent technologies and human resources in the world effectively,
it is essential to update the latest status.
iii. Dissemination to global society
It is essential to promote decommissioning in an open manner to international society forprevention of reputational damages as stated in the Chapter 7 and it should strengthen to distribute
easily understandable information, for helping accurate comprehension from international society.
For this reason, NDF takes dissemination of information about the situation of the Fukushima
Daiichi NPS decommissioning globally through holding side events of IAEA General Meeting andgiving speeches at key international meeting. Furthermore, NDF holds the International Forum on

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the Decommissioning of the Fukushima Daiichi NPS in order to report information about thesituation of the Fukushima Daiichi NPS decommissioning to the world and to take effort tocommunicate with local communities.
iv. Taking part in international collaborative activities
Eight years have passed since the Fukushima Daiichi accident occurred, there is somemovement to apply knowledge acquired from the accident to other issues in abroad.
Decommissioning as a risk reduction strategy is an issue with the highest priority for our country,
it is important to continue to maintain high overseas interest in the Fukushima Daiichi NPS accident
from the viewpoint of gathering knowledge from the world for advancing decommissioning. In
addition, it is also significant to give knowledge acquired through decommissioning back tocollaborative organizations in the world appropriately. Consequently, NDF proactively participatesin international collaborative activities hosted by OECD/NEA and others and provides information
about the Fukushima Daiichi NPS accident to respond to such new interest from the world in apositive manner. It should be continued in cooperation with relevant organizations.

3) Close cooperation with relevant domestic organizations
As stated in Chapter 2, concerning international cooperation, it is promoted that relevant
domestic organizations build and strengthen partnership with foreign organizations in accordancewith the role of each organization. It should be shared the knowledge and human connections
obtained through these activities to ensure consistency of international cooperative activities inJapan and implement effective international cooperation. Therefore, the relationship of relevant
domestic organizations should be further enhanced.

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7 Local community engagement
1) Approaches for local community engagement
In order to implement decommissioning of the Fukushima Daiichi NPS steadily that spans long
periods of time, it must to be seeking for decommissioning developed with the restoration in local
communities under the recognition of “Decommissioning and the reconstruction of Fukushima as
an indispensable pair”.
On that account, understanding and cooperation of the region are essential as it is the first priority
to proceed with efforts toward decommissioning in a safe and steady manner, accurate information
concerning decommissioning should be disseminated at the right time and appropriately. In addition,
it is important to respond to their voices by communicating carefully through dialogues to listen to
the voice of anxieties or questions from the local communities and various standpoints sincerely.
Moreover, we believe that decommissioning can be trusted by the community and co-exist withthe regions, while effectively utilizing the local resources and developing decommissioning or avariety of its relevant activities along with the restoration of the region.

2) Actual effort for better communication
As decommissioning operation proceeds, it is necessary to put into practice information providing
or interactive communication in a further well thought-out manner, under proper collaboration of therelevant organizations including government, NDF and TEPCO.
For instance, NDF hosts International Forum on the Decommissioning of the Fukushima Daiichi
NPS annually and vigorous dialogue about decommissioning with the local citizens and the future
generations who are to face to decommissioning. NDF continues vigorously to promote interactive
communication activities like these and to take all of the local voice sincerely. TEPCO promotes to
accept observers into the Fukushima Daiichi NPS, as well as opened “TEPCO Decommissioning
Archive Center” in November 2018.

3) Measures to reputational damages
There is a possibility that a reputational damage may be caused by being anxious even if the risk
does not become obvious. When delays in responding to reputational damages or troubles on
decommissioning work occur, it may produce a vicious cycle such as downgrading evaluation fromsociety for addressing decommissioning then it causes the further delay of decommissioning
approaches. In order to prevent from a vicious cycle like this, it is the extremely important topromptly reduce existing risks as top priority while making efforts for proper safety management.
Besides, it is crucial to establish trust relationship by communicating regularly with local residents,
as disseminating information on decommissioning should be made at the right time and accurately.

4) Decommissioning that moves forward together with the recovery of thecommunity
Under the recognition of “Decommissioning and the reconstruction of Fukushima as an
indispensable pair”, it is important to address to develop local human resources that will engage
decommissioning and to integrate its relevant industries in conjunction with “Fukushima Innovation

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Coast Framework”, to recover the industry in Hamadori region of Fukushima prefecture where waslost by The Great East Japan Earthquake and nuclear disaster.
For proceeding with decommissioning along with the local reconstruction, it needs to increase
contact with the region, for instance, TEPCO procures materials and services associated withdecommissioning from the local vendors and employs the local workers. On the other hand, it isrequired to balance decommissioning in a safe and steady manner with priority given to the regionin light of the demand to safely promote prompt decommissioning as soon as possible. In order torealize the efforts like these, it is strongly expected that the Fukushima Revitalization Headquarterand Fukushima Daiichi Decontamination and Decommissioning Engineering Company address
various issues by working together in TEPCO, while the relevant organizations including thegovernment, NDF and the local government will coordinate each other. Moreover, an environment
should be improved, of which enables many of the local companies to participate indecommissioning work through using of resources and knowhow that related organizations
obtained and technological and business supports.

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