Rationalization of Radiation Shielding Design for Spent Nuclear Fuel Storage Building

A spent nuclear fuel storage building is generally a structure provided with heat removal, radiation shielding functions, and a seismic design. The facility has air supply ducts and a chimney exhaust duct for removing heat through natural cooling, with the structural shapes determined by the demands of the above functions. In radiation protection design, radiation levels must be kept below acceptable levels for the general public. The radiation dose can be lowered by increasing the concrete thickness, as typically applied in radiation shielding design, or by increasing the distance. The setting of additional shielding plates also helps reduce the scattered radiation escaping from the air supply and exhaust ducts. However, such protective structures against the scattered radiation challenges in effective heat removal and seismic design. Therefore, determining a building structure that can satisfy all safety demands requires a great deal of time. This study aims to effectively achieve radiation shielding. The height and width of the exhaust duct were considered, and the correlation of these parameters was studied. In the calculation, two-dimensional Sn code (DORT) was used to examine the validity of the results. Monte Carlo N-Particle Transport Code (MCNP) calculations were also made for comparison with the DORT results. The cross-section libraries of JENDL3.3 and DLC23F were used in this calculation, with the difference being clarified.