The 2026 edition of the NEA Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS) Benchmarks Workshops gathered more than 280 experts from the international reactor physics community to advance international benchmarking activities and collaboration in modelling and simulation from 11 to 15 May 2026 in Hamilton, Ontario, Canada. Organised by the NEA and hosted by McMaster University, the event  highlighted the importance of WPRS activities in developing rigorous verification, validation and uncertainty quantification (VVUQ) practices for nuclear reactor analysis.
Over five days, experts met in parallel technical sessions to exchange results and discuss ongoing and future benchmark activities in the areas of neutronics, thermal-hydraulics, fuel performance and multiphysics simulations. Discussions covered a wide spectrum of reactor technologies, including light-water reactors (LWRs), high-temperature gas-cooled reactors (HTGRs), sodium- and lead-cooled fast reactors (SFRs and LFRs), and molten-salt reactors (MSRs). Highlights of the event included the launch of a new heat-pipe microreactor benchmark and two topical sessions focusing on modelling and VVUQ of microreactors and molten-salt reactors.
The hands-on part of the fourth edition of the International School on Simulation of Nuclear Reactor Systems (SINUS) was held as a parallel track of the workshop. Twenty-six students received training on novel modelling and simulation tools for multiphysics and VVUQ procedures. The course offers students the opportunity to participate in some of the workshops and exchange with the WPRS participants, connecting the reactor physics experts with their successors.
The WPRS Benchmarks Workshops play a central role in strengthening international collaboration and enhancing the reliability of reactor modelling and simulation. By enabling organisations and countries to compare methods and share data, these activities build confidence in the tools used for reactor design and safety analysis. Their relevance is growing as the nuclear sector advances towards innovative and small modular reactor technologies.
The event was hosted by McMaster University’s Nuclear Operations & Facilities and Department of Engineering Physics, with support from Conexus Nuclear Inc. (formerly CANDU Owners Group).
Workshop outcomes will inform ongoing and new benchmark activities under WPRS, supporting continued collaboration across the international community. Preparations for the next edition of the workshops are already under way.