Risk assessment of filtered-vented containment options for a BWR Mark III containment

The risk reduction achievable in a Mark III containment boiling water reactor (Grand Gulf) by incorporating various types of containment venting systems, as well as other severe accident safety systems, is evaluated. Risk reduction factors of up to 100 were calculated for certain containment venting options. Achievement of this risk reduction potential was found to be dependent upon several factors, including: (1) availability of a service water tie-in to replenish water supplies; (2) ability of the venting system to handle ATWS accidents; (3) ability to eliminate hydrogen burns after significant risk reduction has already taken place; and (4) assumptions made regarding phenomenological uncertainties. The use of high-efficiency filtering media was found to be unnecessary