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QUALITY ASSURANCE ASPECTS OF WASTE EMPLACEMENT AND BACKFILLING IN ILW AND LLW REPOSITORIES

Objective

THE OBJECTIVES OF THE STUDY ARE :

- TO CRITICALLY EXAMINE EXISTING CONCEPTUAL DESIGN PROPOSALS FOR THE DEEP UNDERGROUND DISPOSAL OF ILW AND LLW IN WATER-BEARING (NON-SALIFEROUS) HOST ROCKS, WITH PARTICULAR REFERENCE TO THE QUALITY CONTROL/QUALITY ASSURANCE ASPECTS OF WASTE EMPLACEMENT AND BACKFILLING.

- TO EXAMINE THE EXTENT TO WHICH EXISTING PROPOSALS ENABLE EFFECTIVE MONITORING AND REMEDIAL ACTION TO BE ACHIEVED

- TO IDENTIFY THE PARAMETERS WHICH ARE MOST EFFECTIVE IN DESCRIBING BACKFILL MATERIAL PROPERTIES AND WASTE UNIT CHARACTERISTICS, BOTH BEFORE AND AFTER PLACEMENT.

- TO IDENTIFY APPROPRIATE MEASUREMENT TECHNIQUES AND THE MEANS OF APPLICATION OF SUCH MEASUREMENTS IN THE DEVELOPMENT OF A COHERENT QUALITY CONTROL SYSTEM.

- TO EXAMINE THE WAYS IN WHICH REPOSITORY DESIGN DETAILS, METHODS OF WASTE UNIT/BACKFILL PLACEMENT AND THE SEQUENCE OF OPERATIONS INVOLVED MAY BE ADAPTED TO ENSURE THAT AN EFFECTIVE QUALITY ASSURANCE SYSTEM CAN BE ESTABLISHED.

1. PHASE 1.

WILL COMPRISE A BRIEF REVIEW OF THE FOLLOWING ASPECTS OF THE ILW AND LLW DISPOSAL CONCEPTS DEVELOPED IN MEMBER STATES OF THE EUROPEAN COMMUNITY:
- THE TYPES OF WASTE UNITS ENVISAGED FOR DEEP UNDERGROUND DISPOSAL AND THE QUALITY CONTROL/QUALITY ASSURANCE SYSTEMS CURRENTLY ADOPTED OR ENVISAGED FOR THE PRE-DISPOSAL STAGES.
- THE WASTE EMPLACEMENT SYSTEMS CURRENTLY PROPOSED AND THE EXTENT TO WHICH QUALITY CONTROL/QUALITY ASSURANCE PROCEDURES HAVE BEEN SPECIFIED.
- THE RANGE OF BACKFILL MATERIALS UNDER CONSIDERATION, AND THE PROPERTIES WHICH RELATE MOST EFFECTIVELY TO THEIR INTENTED FUNCTIONS.

2. PHASE 2.

WILL CONCENTRATE UPON THE GENERIC DEEP-LEVEL REPOSITORY DESIGN CONCEPTS FOR ILW AND LLW DISPOSAL (INCLUDING PLUTONIUM-CONTAMINATED WASTES) WHICH ARE INCORPORATED WITHIN THE CURRENT UK WASTE DISPOSAL STRATEGY.

CONSIDERATION WILL GIVEN TO A RANGE OF BACKFILL MATERIALS, REFLECTING THE SCOPE OF CURRENT COMMUNITY RESEARCH AND DEVELOPMENT.

FOR THESE REFERENCE CONDITIONS, MORE DETAILED EVALUATION OF QUALITY CONTROL/QUALITY ASSURANCE MEASURES WILL BE CARRIED OUT, ITEMISING THE PROCEDURES AND MEASUREMENTS REQUIRED AT EACH STAGE OF DEVELOPMENT.

WHERE APPROPRIATE, THE NEED FOR REPOSITORY DESIGN MODIFICATIONS IS TO BE CONSIDERED AS A MEANS OF IMPROVING THE EXERCISE OF QUALITY CONTROL IN THE WASTE EMPLACEMENT/BACKFILLING PROCESSES.

THE FOLLOWING ARE AMONG THE FACTORS TO BE CONSIDERED :
- THE EXTENT TO WHICH BACKFILL MATERIALS CAN BE PREPARED IN SOLID 'FILL BLOCK' FROM OR AS PRE-BATCHED 'FLUID FORM' FILLS AT OFF-SITE PRODUCTION CENTRES, OR AT AN ADJACENT SURFACE FACILITY.
- THE SCOPE FOR PALLETISING WASTE UNITS IN APPROPRIATE SPATIAL ARRAYS, WITH PARTIAL INTERSTITIAL FILLING, PRIOR TO EMPLACEMENT AND FINAL SEALING.
- THE SCOPE FOR EXERCISING CONTROL OVER THE GEOMETRY OF WASTE UNIT ARRAYS SUCH THAT REQUIRED FILL VOLUMES ARE ACCURATELY KNOWN AND DIRECTLY COMPARABLE WITH VOLUMES ACTUALLY EMPLACED.
- MEANS OF SEPARATED MONITORING FOR GROUPS OR 'CELLS' OF EMPLACED WASTE UNITS/BACKFILL, SUCH THAT THE ORIGIN OF DEFECTS MAY BE IDENTIFIED, AND RECOVERY OR APPROPRIATE REMEDIAL ACTION ACHIEVED.
- THE EXTENT TO WHICH THE EMPLACEMENT PROCESSES FOR DIFFERENT CATEGORIES OF WASTE (INCORPORATED IN A SINGLE REPOSITORY) MAY REQUIRE DIFFERENT APPROACHES IN EXERCISING A CONSISTENT LEVEL OF CONTROL.

3. THE STUDY WILL INCLUDE RECOMMENDATIONS CONCERNING THE DEVELOPMENT OF QUALITY CONTROL/QUALITY ASSURANCE PROCEDURES FOR WASTE EMPLACEMENT, BACKFILLING AND MONITORING TO COMPLEMENT AND EXTENT THOSE WHICH ARE BEING (OR HAVE BEEN) DEVELOPED IN RELATION TO THE PRE-DISPOSAL STAGES. SUPPLEMENTARY RECOMMANDATIONS CONCERNING THE CORRELATION OF READILY MEASURED QUALITY CONTROL PARAMETERS AND SPECIFIED PERFORMANCE PROPERTIES WILL BE PROVIDED.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Bullen and Partners, Consulting Engineers
Address

CR9 1PT Croydon
United Kingdom

Participants (1)

Nirex Ltd
United Kingdom