Nuclear Damage Compensation and Decommissioning Facilitation Corporation

The 5 thInternational Forum on the Decommissioning of
the Fukushima Daiichi Nuclear Power Station

Safety and Risk
‐from a perspective of technical strategy‐
November 1, 2021
Kosuke Ono
Program Supervision & Support Office
Nuclear Damage Compensation and Decommissioning Facilitation Corporation (NDF)
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The Organizational Structure Addressing 1F Decommissioning
MOF

The Nuclear Emergency Response Headquarters

Government bondState-backed financial guarantee

Government responsibility for disaster response

NDF

Inter-Ministerial Council•Legally authorized organization under thejurisdiction of METI and MEXT
•Shareholder of TEPCO by a majority of voting
rightsCompensation facilitation•Loan to TEPCO to facilitate compensation•Oversight of corporation management

METI•Mid & long-term technical strategy for D&D•Decommissioning Fund management•Program and project oversight•R&D strategy and planning•Public outreachSupervision of R&D

Decommissioning
fund management
Financial assistancefor compensation
Special charge

NRA
Safety regulation
for specified facility

D&D policy(Roadmap)

Supervision andguidance

TEPCO・HD

Program oversight

D&D facilitation

METI
MEXT

Strategic proposal

Responsible for
Ensuring stable electricity supply
Compensation to the victims
D&D of 1F site as the licensee
Ensuring finance for D&D and compensation
Technical support through R&D

R&D fundPrivate sectors/JAEA/Universities

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NDF’s Activities
Incorporate various proposition focusing on risk reduction into
technical strategic plan and carry out activities to promote
understandings from international community and local regions
through information dissemination and dialogue

 Prepare technical strategic plan
 Risk Evaluation
 Technical Investigation
 Collecting information and research on overseas cases
 Research and Development
 Committees (e.g. Expert Committee on Fuel Debris, Expert Committee on Waste
Management）

 Dialogue and information exchange with relevant parties(TEPCO, ANRE, NRA, Local Governments, Experts, Overseas organizations etc.)
e.g. prepare report on “The way engineering ought to be from the safety andoperator’sperspectives” submitted to TEPCO, ANRE, NRA etc. for their opinions

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Technical Strategic Plan 2021
1. Introduction
2. Concept for reducing risks and ensuring safety
in the decommissioning of 1F
2.1 Basic policy for the decommissioning of 1F
2.2 Concept of reducing risks caused byradioactive materials
2.3 Approach to ensuring safety duringdecommissioning

NDF Web page to get Technical Strategic Plan PDF
https://www.dd.ndf.go.jp/strategic- plan/index2020.html

3. Technological strategies toward decommissioning of 1F（Fuel debris retrieval, Waste management, Contaminated and treated water management,
Fuel removal from spent fuel pools)

4. Analysis strategy for promoting decommissioning
5. Efforts to facilitate R&D

6.

Activities to support our technical stratecy

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Risk Reduction Strategy
Basic Policy for the Decommissioning of Fukushima Daiichi NPS
Continuously and quickly reduce the risks arising from the radioactive materialcaused by the accident that do not exist in a normal NPS

 Five (5) Guiding Principles
・Safe
・Proven・Efficient・Timely・Field-oriented

Risk Level

 Technical Strategic Plan is “Design of Risk Reduction Strategy” inthe middle-long term
Unacceptable area②
Safety First① RiskArea where judgment is madeReduction
whetherArea
wherethe risk level isjudgement
is madeacceptable
or not with close
whethertheriskoflevel
isexaminationdifficultyof risk
acceptable or not with close
reduction
examination of difficulty of risk reduction

Area where risk level
cannot be allowed
when taking a longview of the future.

Broadly acceptable area

Time

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Fig.Nuclear
A5-1 Damage
Changein risk overtime1
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and Decommissioning
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①Concept of Risk Reduction caused by radioactive material (1)SED(Safety and Environmental Detriment) Method expressing the magnitude of risk
level for radioactive materials by“Hazard Potential” x “Safety Management”
 Developed by UK Nuclear Decommissioning
Authority (NDA）and customized by NDF
for 1F

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①Concept of Risk Reduction caused by radioactive material (2)Material Flow
Process to bring major risk sources into the “sufficiently
stable management” region as the immediate goal and thedecommissioning work progress accordingly

Spent fuelstored in SFP

Fuel transported to Common
Spent Fuel Storage Pool after
the accident*New fuel not included(b) Number of spent fuel (units 1 to 4)
Stagnant waterin buildings

Environmental
discharge

AttenuatedContaminatedStructures inbuildings, etc.

Solid waste
storage facility
Adsorption
Vessels, etc.

Zeolite sandbags, etc.

(a) Risk reduction process(C) Cs-137 released at the time of the accident (units 1 to 3) 6
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②Approach to ensuing safety during decommissioning For the unprecedented and technically difficult tasks such as fuel debris
retrieval, in addition to designing/manufacturing method or equipment,
 “safety perspective” as the operator handling potentially hazardous
material, and “field-oriented (operation, maintenance, radiation control,
instrumentation, analysis etc.) perspective” (“operator’s perspective”)
needs to be sufficiently reflected into such method or equipment.

 To achieve the above purpose, these perspectives have to be fullyreflected in the process (project) leading up to the use of method orequipment in the field. Without these perspectives being adequatelyreflected in the project, consequently results (method, equipment etc.)
may be brought which is not suitable for use in the fields, obstructing
safe and stable decommissioning.
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②Approach to ensuing safety during decommissioning – Peculiarity of 1F• A large amount of radioactive material (including α-nuclides that have asignificant impact in internal exposure) is in an unsealed state, as well as inunusual (atypical) and various forms• Barriers for containing radioactive materials, such as reactor buildings andPCVs, are incomplete• Significant uncertainties exist regarding the state of these radioactive materials
and containment barriers, etc.

• Difficulty in accessing the site and installing instrumentation devices to obtain
on-site information due to constraints such as high radiation levels on site
• Since the current level of radiation is high and further degradation ofcontainment barriers is a concern, it is necessary to take measures inconsideration of the time axis without prolonging the decommissioning
activities

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②Approach to ensuing safety during decommissioning – Safety perspective

For unprecedented 1F
decommissioning withsignificant uncertainties,
deliberated safety
evaluation has to be thebasis for making decisions
regarding safetymeasures (concept of“Safety first”). As a result,the decisions will not besignificantly unstable(without excessive or too
little measures) due tovarious elements otherthan safety.

Concept of “Safety first” (conceptual diagram)
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②Approach to ensuing safety during decommissioning –Operator perspective
As 1F decommissioning is unprecedented works, views and feelings ofindividuals engaged in the field works (operation, maintenance,
radiation control, instrumentation, analysis etc.) are important(“operator perspective”).
▶ Complementation of design by operations, including operating controls
Since it is difficult to ensure safety only by design, ensuring safety by both design and operations
together such as “lead & learn” should be effective measures.
▶

Utilization of information in design obtained through monitoring, analysis
To cope with significant uncertainties, it is important to “make a comprehensive use of monitoring(instrumentation monitoring, visual observation, simulation etc.) and analysis.

▶ Handling an abnormality
Assuming also the case of failing procurement of design function (product quality) such as
1F-3FHM malfunction, measures for abnormality (including unexpected events at the timeof designing) shall be prepared with backup of operation in the field.

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②Approach to ensuing safety during decommissioning –ALARPFor safety, there is a minimum level of safety
standards that must be met before the relevant
method or equipment can be used.



At levels above the level that meets this minimum level,
there is a range of choices and, within this range,
methods and equipment to be adopted will be
determined based on trade-off between the safetylevel to be achieved and project cost and duration, akind of “ALARP” (As Low As Reasonably
Practicable) . There is also an issue as to whether
such methods and equipment are feasible in the field.

Based on the above, deciding methods and equipment
to be deployed needs judgment in three areas, whichare “defining the safety standards”, “indicating thefeasibility on-site”, and “examining and discussing
at projects”.

3 regions concerning
safety risk acceptance11

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②Approach to ensuing safety during decommissioning –ALARP① Define the safety standards
to be achieved(Legal/regulatory requirements)

Set management
standards from theoperator’s perspective,
with a margin to safety
standards.
(Operator’s perspective)

Inform retrieval methods andequipment proposals② Examine and discuss
methods and equipment
to be adopted in the
project (ALARP)③ Examine feasibility onsite (by experts).
(Operator’s perspective)

Provide retrieval method andequipment options to meetproject operator’s targets.

④ Determine retrieval methods
and equipment at the project.
Inform availability(if possible)(Safety perspective)

Inform availability(if not possible)
Review management targets in some cases.

ALARP centered on safety（conceptual diagram）

ALARP judgment requires social consensus !

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Dialogue and information exchange with relevant parties
Investigation on cases in UK

Sellafield

Overview of Sellafield Site
(Source: “A Revised Strategy for the Regulation of Sellafield Site” Mina Golshan at RIC 2018)13
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Dialogue and information exchange with relevant parties
Investigation on cases in UK – Regulation at Sellafield
History・Background Despite significant amount was invested by Government during 2000～2013, hazard/risk reduction did not show progress
at Sellafield.
 ONR put the highest priority on hazard reduction at Sellafield as 2014 regulatory issue. To achieve this objective:Regulatory approach on Sellafield shall be fundamentally reviewed and new regulatory strategy shall be formulated
and implemented.

Organization and regulatory method of ONR Sellafield Div. shall be reviewed toward consistent, effective and efficientregulation.

G6（Collaboration with relevant organizations）

G6

ONR, SL, NDA, Department of Energy and Climate Change, Shareholder Executive and Environment Agency… starting at 2014 led by ONRDecide strategy and direction toward acceleration of hazard and risk reductionWhile sharing strategy and direction, each organization plays its individual role (role of ONR as an independent
regulator remains unchanged)

 ONR and operators needs to be understood in the context of liabilities under the regulations
 Independence of ONR as decision maker is indispensable
 ONR continues execution procedures properly Constructive approach shall be adopted, together with operators and relevant parties.
 Innovation shall be promoted to achieve the best safety improvement based on good regulatory practice.

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Dialogue and information exchange with relevant parties
Investigation on cases in UK“How to enable the projects to be moved forward ?” is most difficult for regulator.
– Stop or delay progress is easy !
8 themes/Regulators’ CodeFlexible Permissioning• Sellafield regulatory strategy: prioritization,
eliminating obstacles, finding fit-for-purpose
solution (not 100% perfect solution), riskbalance (long term, short term) etc.
• How regulation should be• Arrangements including regulatory
involvement is agreed by both ONR andoperator (regulation fit for characteristics
of facilities or projects)

Early Engagements• ONR internal process supporting critical orcomplicated regulatory judgement such as
long or short term risk balance (third parties’
opinion on sufficiency of judgement)• Regulatory involvement prior to official application• Promote ONR’s understandings and close arecognition gap between operator and ONR

Enhanced Decision Making Process

Internal Regulator• Support or enforce operator’s self regulation
process• Operator’s ownership of its own liabilities• Merit brought both operator and ONR

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Dialogue and information exchange with relevant parties
Investigation on cases in UK
Status on facilities, Work process

Extract and evaluate event scenario

Special arrangements fit forcharacteristics of facilities or projects

Select event evaluation scenario

Assume protection
measures

Safety evaluation

Judgement criteria

Hazard Management Strategy,
Philosophy & Principles

Scenario
evaluation

Approach for ensuring safety
Lead & Learn Approach

Holistic view Tolerability evaluationof the whole facilities(Intolerable)

Risk Level

Safety ALARP judgment

Unacceptable area

Area where risk level
cannot be allowed
when taking a longview of the future.

Area where judgment is madewhether the risk level is
acceptable or not with close
examination of difficulty of risk
reduction

Broadly acceptable area

Time
Fig. A5-1 Change in risk over time1

Reflect knowledge obtained by preceding projects into later projects: reducing significant
uncertainties systematically and step by step

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Dialogue and information exchange with relevant parties
 How to evaluate and make a judgment on safety for thedecommissioning of reactor damaged by the accident
accompanied by significant uncertainties is both important anddifficult issue to the operator (TEPCO) as well as all parties
involved in the decommissioning.

 NDF plays a leading role to implement the decommissioning of 1F
safely, steadily and quickly with sharing various safety related
issues with parties involved in the decommissioning including
Nuclear Regulation Authority (NRA) and exchanging views of eachparty in a straightforward and sincere manner.
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