Gamma Radiation Shielding Assessment Using Stochastic, Deterministic, and Experimental Methods for RBMK-1500 SNF Storage Cask

This paper presents an evaluation of the gamma-radiation shielding capabilities of the CONSTOR® RBMK-1500/M2 cask dedicated for the storage of spent nuclear fuel at the Ignalina Nuclear Power Plant in Lithuania. This cask is of a new design with increased capacity compared to the older CONSTOR RBMK-1500 and CASTOR RBMK-1500 casks and new facility for their interim storage has been installed. “Hot tests” conducted at this new interim storage facility included dose rate measurements of the CONSTOR RBMK-1500/M2 casks that were loaded with particular sets of spent nuclear fuel half-assemblies and transferred to the facility for subsequent interim storage. Having actual data on the spent nuclear fuel half-assemblies that were loaded into a particular cask, gamma dose rate modeling of that CONSTOR RBMK-1500/M2 cask (namely, cask ID 153) was performed. Modeling was performed using the MCNP (based on the stochastic mathematical method) and the VISIPLAN and MicroShield (both based on the deterministic mathematical method) computer codes. The obtained modeling results were compared between the different codes and with the measurement results. The performed analysis revealed that modeled gamma dose rates are in good agreement for all analyzed codes, although agreement with the measurements is to some extent less.