Participants of the IRPhE Project meeting and the ICSBEP meeting
The annual technical review group and task force meetings of key NEA experimental data evaluation and preservation projects, the International Criticality Safety Benchmarks Evaluation Project (ICSBEP), the International Reactor Physics Experiments Evaluation Project (IRPhE) Technical Review Group (TRG), the Shielding Integral Benchmark Archive and Database Task Force (SINBAD TF) and the TRG for the International Assay Data of Spent Nuclear Fuel Database (SFCOMPO) were held on 14-18 April 2025 in Ljubljana, Slovenia. The meetings brought together over 100 experts – experimentalists, practitioners, and modellers – from sixteen countries to review candidate evaluations, discuss emerging issues, and enhance data accessibility. Meeting participants also had the opportunity to visit the TRIGA reactor at the Jožef Stefan Institute (JSI), which hosted the meetings.
Holding these meetings back to back has contributed to fruitful exchanges across communities and sectors for the mutual benefit of all ongoing NEA experimental data evaluation and preservation efforts in nuclear science. The next NEA benchmark evaluation meetings will take place in the second quarter of 2026.
Criticality and reactor physics
The ICSBEP approved eight new criticality benchmark evaluations for inclusion in the next edition of the ICSBEP Handbook. Approved experimental benchmarks included high Pu240 content fast spectrum experiments reflected by ead and opper; antalum experiments in a water reflected array; sodium chloride absorbers in thermal and fast spectra; highly enriched uranium reflected by opper in a fast spectrum; along with shielding experiments involving polytetrafluoroethylene (PTFE) and aluminum, and fundamental physics measurements of subcritical systems.
During the IRPhE Project meeting a new benchmark was approved for the next edition of the IRPhE Handbook on intra-pin reaction rate experiments at the CROCUS facility, which aim to provide much needed data to validate high-fidelity neutronics simulations of pin powers.
Shielding, used fuel, decay heat data
The SINBAD TF welcomed the approval of two new shielding evaluations and considered eleven experimental proposals or numerical intercomparisons — either in the proposal phase or approaching completion — representing a notable step forward in this area after over 15 years of limited development. Meanwhile, the SFCOMPO-TRG approved a new used fuel inventory benchmark for the Beznau BM1 MOX fuel sample experimental data from the ARIANE project. SFCOMPO has four additional entries close to finalisation. While the focus was on spent fuel covering PWR and BWR technologies, discussions were initiated on including available decay heat data for fast spectrum systems.
Participants of the SINBAD Meeting
Over the past two years, the SINBAD Task Force (TF) successfully migrated its database to the NEA GitLab system, significantly improving the traceability and transparency of the maintenance process. At the same time, SINBAD’s license conditions were revised. Licensees now can open issues and propose direct improvements to evaluations within the GitLab platform — an approach inspired by successful open-source software development models, encouraging user contributions through a crowd-sourcing framework. Following SINBAD’s example, the SFCOMPO-TRG has decided to adopt a similar approach, which will also streamline the integration of decay heat data into its database and will enable an efficient framework for better collaboration.
Both the SINBAD TF and the SFCOMPO-TRG also discussed the standardisation of machine-readable data formats and the development of Application Programming Interfaces (APIs) to align with the FAIR (Findable, Accessible, Interoperable, Reusable) data principles.
The SFCOMPO and SINBAD expert communities reaffirmed their commitment to maintaining the highest quality standards for their mandated missions to collect, evaluate, and disseminate high-quality experimental data and benchmarks that address the needs and interests for nuclear science and engineering applications. Through robust oversight and quality processes, they ensure the continuous availability of highquality, FAIR-compliant data, supporting the growing application of SFCOMPO and SINBAD datasets in machine learning and other advanced research fields.
JSI TRIGA reactor deck
JSI TRIGA reactor hot cell
