A scenario analysis was performed for microbial effect on the performance assessment (PA) of the high-level radioactive waste disposal system. Based on review of recent literature on PA and some results of our experiment, possible scenario of microbial effects on the Japanese high-level radioactive waste disposal system were analyzed. The result of the analysis shows that the microbial effect on groundwater evolution, which is caused by the microbial redox reaction, is one of the most important issues in assessing PA. The evolution not only affects radionuclide migration but also the life-time of metal overpack corrosion.To assess the microbial effect on groundwater evolution, a numerical estimation code is required, with reliable parameters for analysis of microbial activities used in the code. A biological parameter database has been developed to give the growth and metabolism of the six typical microbial groups to be used in the estimation code. For this purpose, about 573 data from 95 papers were examined to obtain effective data for disposal. The database is composed of significant data like specific growth rate, maximum growth rate, constant decay rate, and experimental condition for model assessment.
Fabricated stainless steel structures are susceptible to stress corrosion cracking (SCC), despite being placed in chloride-containing natural water or humid atmospheres. The present paper describes a model that can define the conditions under which SCC is initiated and propagated, based on analyses of actual SCC incidents induced at welded flanges of cylindrical stainless steel structures.Whenever the vitrified radioactive waste canister storage conditions deviate from normal and appropriate conditions due to earthquakes or tsunamis, the exposed canisters are expected to suffer SCC within 400 hours to 7 years, according to the analytical results obtained such as degree of sensitization, residual stress distribution, chloride ion concentration, and temperature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.