APPLICATION OF ADVANCED NEUTRON ABSORBING MATERIALS TO STRUCTURAL MATERIAL OF INNER BASKET OF STORAGE CASKS FOR HIGH BURNUP AND MOX SPENT FUELS

For transport and storage of high burnup and MOX spent, fuel, developm ent of inner baskets becomes very important in terms of subcriticality , and heat removal. Advanced neutron absorbing structural materials, w hich contain high concentration of boron or enriched boron, such as (1 ) Berated stainless steel, (2) Berated aluminum alloy, (3) Berated com posite (three layered clad plate composed of berated stainless steel/c opper/borated stainless steel structure) were considered suitable for the structural material of the inner baskets. Improvements of thermal conductivity and mechanical strength as well as neutron absorbing char acteristics of these materials were studied at first. Then requirement s of heat removal and subcriticality of the baskets using above neutro n absorbing structural materials are investigated. As the result, simp le and effective basket structure with appropriate boron and enriched boron contents required was obtained. In conclusion, highly performanc e inner baskets and casks were designed, which can store high burnup a nd MOX spent fuel effectively. Applications of advanced neutron absorb ing structural materials to the inner basket were shown very useful in order to contain highly radioactive and heat generating spent fuel.