The OECD NEA Working Party on Nuclear Criticality Safety Recent outcome, work in progress and outlook

The Working Party on Nuclear Criticality Safety (WPNCS) was established in 1996 at the Nuclear Energy Agency (NEA) of the Organisation for Economic Cooperation and Development (OECD), following previous criticality-related investigations at the NEA, notably a series of benchmarks on criticality calculations, the International Criticality Safety Benchmark Experiments Project (ICSBEP) and an expert group on needs for critical experiments. With a wide range of activities covering fundamental aspects related to modelling and simulation, including bias and uncertainties estimates, to more application-oriented aspects, leading e.g. to the application of burn up credit approaches, and finally providing reference experimental data through dedicated preservation efforts, the WPNCS spans numerous aspects of criticality safety. Its work relies on the contribution from recognized high level experts from across the NEA member countries, focusing on topics of common interest and mutually beneficial efforts. The WPNCS is thus a unique venue to address criticality safety challenges at the global level. Over the 25 years of its existence, the WPNCS has contributed with developing methods and approaches now widely used in the nuclear sector for improved safety and design or operational solutions. This paper provides an overview of the methods of work of the WPNCS, recent outcome of its activities, as well as work in progress and future perspectives.