An assessment of radiological source terms for loss of cooling and coolant accidents of a PWR spent fuel pool

摘要

This paper presents the MELCOR code simulation study regarding how a dedicated severe accident mitigation (SAM) measure the release of radiological FPs to the environment in the spent fuel pool (SFP) of a reference pressurized water reactor (PWR) plant. To draw up relevant insights, a series of accident scenarios have been investigated, taking into account a combination of two initiating events (loss-of-cooling and loss-of-coolant accidents), two SFP operating modes (normal and refueling), and three external water makeup strategies through an external cooling water injection as one of dedicated SAM strategies for a long-term cooling of the SFP. For the analysis, relevant code modeling has been made for a broad spectrum of severe accident-related phenomena being expected during the SFP accidents. As a result, the evolution of relevant physical phenomena has been investigated and discussed in light of the release of FPs, and several points of uncertain issues, which need to address more carefully (a) either when implementing a cross-comparison for different code predictions (such as MELCOR and MAAP) for SFP accident progression or (b) when assessing radiological risk and/or developing dedicated SAM strategies for the SFP of PWR plant, have been drawn up.