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STRATEGY FOR SAFETY CASE DEVELOPMENT:IMPACT OF A VOLUNTEER APPROACH TO

SITING A JAPANESE HLW REPOSITORY

K. Kitayama, K. Ishiguro, M. Takeuchi, H. Tsuchi, T. Kato, Y. Sakabe, K. Wakasugi

Nuclear Waste Management Organization of Japan (NUMO)

SAFETY CASE FOR THE DEEP DISPOSAL OF RADIOACTIVE WASTE: WHERE DO WE STAND?

23-25 JANUARY 2007

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Development of the Japanese HLW Disposal ProgramDevelopment of the Japanese HLW Disposal Program

1976

1992

20102020

20302040

Start of R&D Program

Second Progress Report (H12)(Technical Reliability)

"Specified Radioactive Waste Final Disposal Act" (June. 2000)

Establishment of NUMO as the Implementing Organization (Oct. 2000)

Selection of Disposal Site(around 2025)

Repository Operation(around 2035)

20022002

Commencement of Open Solicitation (Dec. 2002)

2005

R&D Program of supporting Organizations

First Progress Report (H3)(Technical Feasibility)

R&D

Implementation

20002000

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Three Stages of the Site Selection ProcessThree Stages of the Site Selection Process

Investigation areas:Volunteer areas and their surroundings

Investigation methods:Literature surveys

Investigation areas:PIAs

Investigation methods:Initial surface exploration;boreholes, geophysics, etc.

Selection of DIAsInvestigation areas:

DIAsInvestigation methods:

Detailed surface exploration plus characterisation in underground facilities

Selection of repository site

Volunteers

Selection of PIAs

PIAs DIAs Repository Site

PIAs: Preliminary Investigation AreasDIAs: Detailed Investigation Areas

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Practical ConstraintsPractical Constraints2002 2007? Solicitation

All municipalities LSAll volunteers PI

around 2025 DI

2 DIAs

Up to 5 PIAs

Decision point- for LS, geological stability (EFQ)- for PIA, ease of making basic safety case- for DIA, provisional safety case- for Site, safety case for licensing

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Level 1

Level 2

Level 3

Other Supporting Documents

Development of repository concepts for volunteer

siting environments

Scientific background and practical application of NUMO’s

repository siting factors

Siting Factors

Outreach Scheme

- JSCE reports- Catalogue of Quaternary Volcanoes in Japan

- H12 report, etc

- H12 report- Study on Implemen-tation Techniques forHLW Disposal(by utilities), etc

Repository Concepts

Video

Booklet

Instructions for Application

Structure of Information Package for Open SolicitationStructure of Information Package for Open Solicitation

Open Solicitation of Candidate Sites for Safe Disposal of High-Level Radioactive Waste

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Outline of Literature Survey (LS) ScheduleLS stage PI stage

Collection, Summarization and Assessmentof Literature Information

Feasibility Study of System Designand Performance Assessment

Assessment for Selection of PIAs

Siting Factors for PIAs

LS Plan

Siting Factors for DIAs

PI Plan

RC Development Report

PIA Selection Report

Surface-Based Investigations

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Key Elements for assembling a Safety Case

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Earthquake / fault activity Igneous activityUplift / erosionUnconsolidated Quaternary depositsMineral resources

Factors to assess characteristics of PIA comprehensively (and comparatively) for areas where compliance to the legal requirements has been confirmed, which are relevant to:

Favourable Factors (FF)

Evaluation Factors for Qualification (EFQ)

Factors to assess compliance with legal requirements for PIAs, which are relevant to:

Legal requirements of DIA selection and repository site selection Practicality of repository construction and operation

Siting Factors for PIAs Selection (LS stage)

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Requirements for Requirements for NUMONUMO’’ss Safety EvaluationSafety EvaluationDeal with a range of repository

concepts and a variety of volunteer sites

Major extension from H12:- Evaluate pre-closure safetyand engineering practicality- Evaluate post-closure safety more realistically and develop relevant tools - Develop tools enable more rigid coupling of siting, design and PA- Develop supporting management tools

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The NSA: Application to RC DevelopmentThe NSA: Application to RC Development

The NUMO Structured Approach The NUMO Structured Approach (NSA) is a methodology for (NSA) is a methodology for developing designs which:developing designs which:

Tailors repository concepts Tailors repository concepts to sites in a transparent to sites in a transparent mannermanner

Responds to increasing site Responds to increasing site understandingunderstanding

Allows for developments in Allows for developments in science & technologyscience & technology

Accepts potential changes to Accepts potential changes to sociosocio--political boundary political boundary conditions over the long conditions over the long implementation periodimplementation period

Feedback provides identification Feedback provides identification and prioritisation of and prioritisation of

Site characterisation goalsSite characterisation goals

R&D to support design & PAR&D to support design & PA

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Stepwise Development of Safety CaseStepwise Development of Safety CaseLS Stage

- Data source: literature information for the site, complemented by generic and international experience

- The largest uncertainties with the geological environment- EBS or near-field processes provide a robust safety case- Qualitative arguments may provide strategy and guidance for

the development of the RC and safety case at later stage. PI Stage

- More quantitative evaluations based on surface geological investigations and modelling

- Detailed coupling between site investigation, design and PA are critical for repository development.

- An emphasis may still be placed on EBS performance in siteswith limited geological information.

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Stepwise Development of Safety CaseStepwise Development of Safety Case (continued) (continued) DI Stage

- Site specific data from investigations in the underground characterization facility available, with additional boreholes and detailed geophysical surveys

- Safety case required to be more convincing and completeto justify the construction of a repository at a selected DIA,and to demonstrate compliance with regulations

- All relevant interactions between the EBS and natural barriersconsidered in design optimization

- All safety relevant information from diverse sources integrated into the entire safety case Stages after licensing (construction/operation/closure)

- Safety case evolves to maintain state-of-the-art, with input from characterization during construction and experience gained during operation, and monitoring.

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ConclusionsConclusionsNUMO`s strategy for safety case development is constrained by staged siting and the volunteering approach.NUMONUMO’’ss safety casesafety case is developed iteratively in the framework of the NUMO Structured Approach.At early stages of siting, major components of the safety case will be regularly documented in technical reports. Discussion of later safety case documentation continues. Items important for safety case development include :- Linkages between site investigation, repository design and performance assessment- Emphasis on near-field processes / robust EBS at early stages- Integration of operational phase safety and engineering system practicality into the total safety case

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Further Information on:Further Information on:www.numo.or.jp/englishwww.numo.or.jp/english//