Rational Shielding Ability Evaluation for a Modular Type Interim Storage Facility

Abstract

This paper discusses a rational methodology to evaluate dose rate at the boundary of the interim storage facility using two methods; 1) a method taking into account``shade eŠect'' which represents the self-shielding eŠect of interim storage containers, 2) utilization of a newly developed simpliˆed code. It was proved that the method of the shade eŠect is applicable to the secondary gamma-ray, which dominates approximately 50 of the total eŠective dose rate. Thus, the eŠective dose rate attributed to the secondary gamma-ray depends on both the number of containers in the facility and the shade coe‹cient which represents the factor of the shade eŠect. Using this shade coe‹cient, the dose rate was estimated for the facility that stored 8 or 16 containers around the boundary of the facility and the results were consistent with that of the Monte Carlo calculation. In the present study, a simple neutron transport code, MCNP-ANISN_W, was newly developed aiming at the simpliˆcation of large-scale calculation. The results of the dose rate agreed well with that of the Monte Carlo calculation. The results of the present study show that the simple evaluation technique and the code developed in this study would be useful for the evaluation of dose rate around the boundary of the interim storage facility.

Monte Carlo Shielding Calculations for a Spent Fuel Transport Cask with Automated Monte Carlo Variance Reduction

“…The transport calculation is performed by ANISN-W 13) code. (2) to (8). (10) The process of the adjoint flux calculation in a certain mesh from (2) to (9) is iterated by the number of particle histories.…”

“…The purpose of the present study is to perform, compare and analyze the shielding calculations for a transport cask in detail with the variance reduction technique based on the Consistent Adjoint Driven Importance Sampling (CADIS) methodology [5][6][7][8][9] and the empirical formula. 10) CADIS methodology makes use of the adjoint function that is associated with particle importance which is the contribution of a particle with respect to the objective.…”