The main mission of the Working Group on Fuel Safety (WGFS) is to advance the current understanding and address cross-cutting issues related to fuel behaviour in accident conditions, including work on associated aspects of thermal-hydraulics, oxidation, chemistry, mechanical behaviour and reactor physics.
Specifically, the WGFS:
The Working Group aims at facilitating international convergence in fuel safety issues, including experimental approaches, interpretation and use of the experimental data or of other relevant information.
Co-operation with other NEA bodies is actively pursued, as appropriate, e.g. with the Working Group on the Analysis and Management of Accidents (WGAMA) on issues involving thermal hydraulics and/or fuel damage, with the Working Group on Fuel Cycle Safety (WGFCS) on fuel-storage issues and with subsidiary bodies of the Nuclear Science Committee (NSC) working on fuel issues. This results in optimisation of both the resources mobilised by member countries for NEA activities and the quality of the work produced.
The Working Group performs its activities mainly through organising topical meetings on specific subjects or through task forces dedicated to covering specific programme items.
The expert group provided advice to the Working Party on Scientific Issues of Reactor Systems (WPRS) on the scientific development needs (data and methods, validation experiments, scenario studies) of sensitivity and uncertainty methodology for modelling of different reactor systems and scenarios. It was completed in 2020 and the topic is currently addressed in the Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS).
The Working Group on the Analysis and Management of Accidents (WGAMA) is responsible for activities related to potential accidental situations in nuclear power plants, including the following technical areas: reactor coolant system thermal-hydraulics; design-basis accidents; pre-core melt conditions and progression of accidents and in-vessel phenomena; coolability of over-heated cores; ex-vessel corium interaction with coolant and structures; in-containment combustible gas generation, distribution and potential combustion; physical-chemical behaviour of radioactive species in the primary circuit and the containment; and source term. The activities mainly focus on existing reactors, but also have application for some advanced reactor designs. Priority setting is based on established CSNI criteria and in particular on safety significance and risk and uncertainty considerations.
The objective of the Working Group on Fuel Cycle Safety (WGFCS) is to advance the understanding of relevant aspects of nuclear fuel cycle safety, including: uranium mining and milling; uranium refining and conversion to uranium hexafluoride; uranium enrichment; fuel fabrication and storage (including MOX fuel); spent fuel storage; spent fuel reprocessing; decommissioning of nuclear facilities; radioactive waste management and disposal options (including for spent fuel) and the research and demonstration facilities that support these activities.
This working group's objective was to advance the current understanding and to address safety issues related to fuel safety margins, in particular to systematically assess the technical basis for current safety criteria and their applicability to high burn-up and to the new fuel designs and materials being introduced in nuclear power plants.