Assessment of radiological safety of Wolsung site at site boundary considering crack impact

摘要

The number of spent fuel storage facilities in the world continues to increase because of "Wait and See" policies and delay of a permanent disposal plan. The temporary spent fuel storage concept is changing to a pre-disposal storage concept. Strengthened safety concepts are required for expanded spent fuel storage facilities and sites. The Korea Hydro and Nuclear Power Company is planning to construct a reinforced concrete MACSTOR-400 facility at Wolsung. In concrete dry spent fuel storage structures, cracks can occur due to radiant heat and environmental chloride. The likelihood of cracking increases over time. Research on changes in shielding performance from one collinear crack in the surface of a concrete facility has been carried out. However there is no research about public radiological safety which considers the potential radiological impact from multiple cracks. Additionally, in cases where several nuclear facilities are operating at the same site, the total dose rate from the entire complex has to be maintained under dose rate criteria.rnThis paper estimates the radiological safety of the Wolsung site, measured at the perimeter, considering crack impacts. The effects of cracks on dose rate from previous experiments, combined dose rate from all facilities at Wolsung and additional dose rate due to future expansion plans were considered. If the real geometry of the cask storage area (mutual shielding) is considered, the total dose rate expected at the site perimeter is reduced by about forty percent. It is estimated that regardless of crack formation the dose rate can be maintained within dose limits throughout the lifetime of the facility.