Assessment on Accident and Mitigation of Spent Fuel Pool in a Typical PWR

Abstract

In consideration of low power rate and large water inventory in spent fuel pool (SFP), the accident progression may be very slow and the fuel melt accident was considered to be very unlikely in SFP. However, the accident in Fukushima Dai-ichi Nuclear Power Plant implies the possibility of severe accident in SFP and highlights the importance of accident management of SFP. As the fuel building has no three-barriers containing radioactive products like the reactor building and SFP has significantly larger fuel inventory, the potential consequences of severe accident (radioactive materials release and hydrogen production) could be far beyond the capability of practical mitigation measures in design. Since Fukushima accident, lots of efforts related to SFP simulation are made by developers of several severe accident simulation codes. For ASTEC code, models about radiative heat transfer and Zircaloy oxidation are added in V2.1 which makes it possible to have a better prediction of severe accident in SFP. In this paper, representative scenarios (loss of coolant, loss of cooling) in SFP of a typical pressurized water reactor (PWR) design are simulated with ASTEC code. Accident progression and phenomena are presented. The influence of potential mitigation measures is studied. Suggestions to the design of SFP and accident mitigation strategies are provided according to the analysis results.