ASNR Work on the Nuclear Criticality Safety of TRISO Fuel

The French nuclear energy landscape is currently experiencing a renewal, including innovative reactor designs. Among innovative reactor concepts, some use TRi-structural ISOtropic (TRISO) particle fuel. The implementation of such new fuel presents a challenge for nuclear criticality safety (NCS) assessment during operations in nuclear power plants, in manufacturing and reprocessing facilities, as well as during transportation. To support future NCS assessments, the newly established French nuclear safety authority (ASNR), resulting from the merging of the former authority and its technical support organization (IRSN), needs to compute its own criticality safety standard values for TRISO fuel. These values, as well as sensitivities to various physical parameters relative to TRISO fuel, will be necessary to perform NCS assessments and to define the NCS parameters to be ensured during fuel fabrication. This paper presents a summary of the main studies performed at the ASNR regarding the NCS assessment of TRISO fuel throughout 2025.