Accelerating VVER-440 decommissioning by shortening spent-fuel cooling time for dry-cask storage

This study focuses on optimizing the cooling time of spent nuclear fuel in the spent nuclear fuel pool before its placement into a dual-purpose dry cask to reduce the overall cooling duration required to safely store fuel discharged from the VVER-440 reactor. The feasibility of reducing the cooling time is assessed based on the analysis of decay heat and the evaluation of the dose rate equivalent on the cask surface and at a standardized distance of 2 m from the cask. To reduce the cooling time, the peripheral layer of spent nuclear fuel in the cask, consisting of 30 storage positions, is replaced with hexagonal fuel dummies made of polyethylene, steel, or their combination. The results obtained apply to standard spent nuclear fuel management practices, particularly in the context of nuclear power plant decommissioning or other scenarios where minimizing the residence time of fuel in the pool is of critical importance.