A three-dimensional model of radionuclide migration from a canister of spent nuclear fuel

António J. de C. Pereira

Abstract


The development of a three-dimensional model of the near-field of ageological repository for spent nuclear fuel is described. The near-fieldcomprises a canister where the spent fuel is enclosed, a layer of bentoniteclay around the canister, a backfilled tunnel over the canister’s depositionhole and finally, the fractured rock adjacent to the bentonite and the tunnel.The main transport processes are diffusion, sorption, radioactive decayand groundwater flow. A mathematical model attempts to couple thewater flow to the mass transport. This model has been simplified to reduceits computational complexity. Our results are compared with the results ofa compartment model obtained from the literature. It is concluded from theagreement between our 3D model and the compartment model, that theresistance approach used in one-dimensional compartment models isrobust enough for use in models for probabilistic risk analysis of long-termperformance of a geological repository.The development of a three-dimensional model of the near-field of ageological repository for spent nuclear fuel is described. The near-fieldcomprises a canister where the spent fuel is enclosed, a layer of bentoniteclay around the canister, a backfilled tunnel over the canister’s depositionhole and finally, the fractured rock adjacent to the bentonite and the tunnel.The main transport processes are diffusion, sorption, radioactive decayand groundwater flow. A mathematical model attempts to couple thewater flow to the mass transport. This model has been simplified to reduceits computational complexity. Our results are compared with the results ofa compartment model obtained from the literature. It is concluded from theagreement between our 3D model and the compartment model, that theresistance approach used in one-dimensional compartment models isrobust enough for use in models for probabilistic risk analysis of long-termperformance of a geological repository.

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References


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DOI: http://dx.doi.org/10.1260/175095407781421630

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