The BEPU Challenge in Current Licensing of Nuclear Power Reactors

Several ways can be adopted to define BEPU, one of this being “BEPU connection between SYS TH code development and V&V, Scaling, Uncertainty on the one side and licensing process on the other side.” Then, “BEPU is the application of SYS TH codes.” The BEPU process shall be associated with the licensing process. The licensing process noticeably includes the PSA together with a number of methods not discussed in the present book; those methods including PSA need a cross-link with BEPU. AA is part of the licensing process. Among the general attributes of AA, the first one shall be the compliance with the established regulatory requirements. The second attribute deals with the adequacy and the completeness of the selected spectrum of events. The achievement of the spectrum of events (or envelope) shall be the result of the combined applications of deterministic and probabilistic methods. The third attribute is connected with the knowledge base including that captured by the qualified computational tools and analytical procedures suitable for the analysis of transient conditions envisaged for individual (concerned) NPP. The complexity of a NPP and/or the accident scenarios may prove challenging for a conservative analysis, thus justifying the choice for a BEPU approach. This implies two main needs for nuclear thermal-hydraulics: (a) to adopt the current computational tools, proving (to the regulatory authority) an adequate quality via suitable V&V and (b) to adopt a qualified uncertainty method.