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

We have recently performed a probabilistic risk assessment of filtered-vented containment system design concepts for a Mark I containment boiling water reactor. Our objectives were to identify the most promising accident mitigation strategies and design options from among several candidates, to identify the factors that could limit their effectiveness, to estimate the net risk reduction potential, to elucidate certain reliability objectives and performance requirements, and to help the NRC to prioritize research needs. In addition to meeting these objectives, an important accomplishment of the study was the development of a risk assessment methodology to assess accident mitigation alternatives. The results indicate that some venting strategies will achieve significant risk reductions (factors of 40 to 400) for the Mark I BWR if certain design provisions are included to circumvent potential problem areas