ABSTRACT
Conventional Probabilistic Risk Assessment (PRA) methodologies and software tools developed for a variety of risk-informed applications are also characterized as ‘static’, referring to the fact that temporal and phenomenological aspects of risk scenarios are at best implicit in the models and results. For instance, typical core melt cut sets are essentially logical combinations of contributing events, without consideration of possible effects of different time ordering of the constituent events, and timing of event initiation or termination. Over the past three decades a small community of researchers have directed toward developing and exploring possible benefits of dynamic PRA methods and tools. Dynamic methodologies provide a natural framework to include physical models, mechanistic models of hardware failure or human operator behavior models. In this paper, the capabilities to link conventional PRA platforms with dynamic PRA tools are described and the concept of cut set diffraction is introduced. This facilitates the use of newer risk analysis methods while still using the existing probabilistic information that, at least in the U.S., is available for every Nuclear Power Plant (NPP).
