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COLLOIDS RELATED TO LLW AND MLW .

Objective

THE PRIMARY AIM OF THIS WORK IS TO DEVELOP RESEARCH MODELS WHICH EXAMINE IN DETAIL THE APPROXIMATIONS AND ASSUMPTIONS IMPLICIT IN THE ASSESSMENT MODELS THAT ARE USED TO ANALYSE REPOSITORY BEHAVIOUR. THE ASSESSMENTS MODELS ARE NECESSARILY RELATIVELY SIMPLE. THEY MUST MAKE ASSUMPTIONS IN MANY AREAS INCLUDING THE TIME EVOLUTION OF THE REPOSITORY CHEMISTRY, THE INFLUENCE OF CORROSION PRODUCTS ON LOCAL CHEMISTRY ETC. THE RESEARCH MODELS USE DATA FROM EXPERIMENTAL PROGRAMMES TO STUDY THESE POINTS IN DETAIL.

THE NEAR FIELD HAS A COMPLEX CHEMISTRY WHICH DETERMINE THE SOLUBILITY OF RADIONUCLIDES. THIS CHEMICAL ENVIRONMENT CHANGES BOTH WITH TIME AND SPATIALLY THROUGHOUT THE NEAR-FIELD REGION. THE ENGINEERED BARRIERS ARE VERY DIFFERENT CHEMICALLY TO THE SURROUNDING GEOLOGY AND SO WILL NOT ONLY DEGRADE WITH TIME BUT MAY ALSO CAUSE A FRONT OF PERTURBED CHEMISTRY HAVE LARGELY BEEN NEGLECTED. YET THESE PROCESSES UNDERLIE MOST OF THE ASSUMPTIONS IN THE SIMPLE NEAR-FIELD MODELS. THE CONDITIONS OF PRIMARY INTEREST TO OUR PROGRAMME CONCERN THE WASTE CONTAINED IN A STEEL CANISTER AND BURIED IN A CONCRETE ENVIRONMENT.

B1. DEVELOPMENT OF THE CHEQMATE COMPUTER PROGRAM WHICH COUPLES CHEMICAL EQUILIBRIA (VIA. THE PHEEQE CODE) WITH IONIC DIFFUSION AND ELECTROMIGRATION.

B2. INCORPORATION OF IONIC ADVECTION IN FLOWING SYSTEMS IN THE CHEQMATE CODE.

B3. INCORPORATION OF IONIC ACTIVITIES IN THE TRANSPORT PART OF CHEQMATE FOR APPLICATIONS BEYOND THE DILUTE SOLUTION LIMIT.

B4. APPLICATION OF CHEQMATE TO COUPLED CHEMISTRY AND TRANSPORT PROBLEMS RELEVANT TO THE NEAR FIELD OF A REPOSITORY, FOR EXAMPLE THE TIME AND SPACE DISTRIBUTION OF THE OXIDATION POTENTIAL IN THE BACKFILL PORE WATER, THE EXTERNAL CHEMISTRY ON THE NEAR-FIELD COMPONENTS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

United Kingdom Atomic Energy Authority
Address
353,Harwell
OX11 0RA Didcot - Oxfordshire
United Kingdom