A Vault Model for the Assessment of Used Fuel Disposal in Canada

Abstract

AbstractThe environmental assessment of the geological disposal of used nuclear fuel involves the assimilation of experimental results to produce an estimate of the potential impact of a disposal vault on man and the environment. In this paper we briefly outline the assessment methodology and expand upon one aspect of the data assimilation process, namely, the incorporation of research results on the performance of engineered barriers into assessment models.The model to be discussed represents (i) failure modes for titaniumbased containers, including short-term failures due to undetected manufacturing defects and long-term failures due to uniform and local corrosion; (ii) release of radionuclides from used fuel, including relatively fast release of soluble fission products from gap and grain boundaries and slow, congruent release controlled by the dissolution of the fuel matrix itself; and (iii) mass transport of released radionuclides through the clay-based sealing materials surrounding the waste container, including diffusion, convection and radionuclide storage (sorption or retardation) effects.