Development of Fuel Route/Dropped Load PSA for UK ABWR

Abstract

Generic Design Assessment (GDA) of Hitachi-GE’s United Kingdom (UK) Advanced Boiling Water Reactor (ABWR) was completed in December 2017. Various Probabilistic Safety Assessment/Analyses (PSAs) are utilized to provide the risk insights for design of UK ABWR. This paper provides the characteristics of “Fuel Route/Dropped Load” PSA which is included in the scope of UK ABWR PSA and focuses on the effects of dropped load. “Fuel Route” means the all areas where the new or spent fuels are moved or stored. Shutdown PSA and Spent Fuel Storage Pool (SFP) PSA cover large parts of risk assessment for the fuel route. However, large number of lifting operation such as refueling with fuel handling machine or heavy equipment lifting operation including cask operation by reactor building crane should be considered separately from Shutdown PSA and SFP PSA. That is because dropped loads potentially caused by such lifting operation may not always cause initiating events considered in the Shutdown PSA or SFP PSA but potentially cause a mechanical failure of the spent fuels and subsequent radiological consequences. “Fuel Route/Dropped Load PSA” is additionally developed and quantified to address the potential radiological release due to the lifting operation.