Fuel Route Risk Assessment Framework and Pilot Plant Application

Abstract

Damage to fuel assemblies and the release of radioactive substance may occur during fuel lifting and storage in nuclear power plant. For the purpose of quantitatively evaluate internal events, internal and external hazards induced risk of spent fuel pool and related fuel lifting facilities, to identify weaknesses of the fuel route design and provide corresponding risk insights, the methodology of fuel route probabilistic safety assessment (PSA) is systematically summarized in this study, and based on the design characteristics of a specific pressurized water reactor nuclear power plant, fuel damage frequencies and radioactive substance release frequencies in the fuel route are assessed, some possible further safety improvements for the fuel route are identified. The results of analysis case show that the fuel building ventilation system failure has the largest contribution to the overall fuel thermal damage frequency, while the spent fuel crane failure has the largest contribution to the overall fuel mechanical damage frequency. The drop of the spent fuel cask full of spent fuels in loading pit has a prominent contribution to the risk of radioactive substances release due to the mechanical damage. The safety risk in the fuel route can be effectively reduced by the diversified design of local cooling unit fans in fuel building ventilation system and type modification of the spent fuel pool crane.