Research reactor CABRI restarts after an important upgrade

The CABRI research reactor has once again achieved criticality after several years of renovation and modification work. Operational preparation for the CABRI International Program (CIP) for the study of reactivity accidents can now go ahead. Led by IRSN under the aegis of the NEA, CIP involves 18 partners from 12 countries.

The divergence of the CABRI research reactor in October 2015 is the culmination of several years of renovation and modification of the facility. This achievement was the last technical step prior to the operational implementation of the Cabri International Program (CIP), an international research program led by IRSN under the aegis of the OECD NEA and devoted to reactivity initiated accident experiments.

During a reactivity accident, some of the fuel assemblies making up the reactor core can be subject to a significant power surge for a few milliseconds, exposing the fuel elements to extreme loads, which may cause their destruction. It is therefore essential to verify experimentally the effects of such loads on fuel elements, in order to understand safety margins and adapt regulatory safety criteria where necessary. This is the goal of the fuel tests conducted in CABRI, a reactor with outstanding characteristics which make it unlike any other facility in the world.

CABRI is designed to produce rapid power transients. Its new water loop reproduces the pressure (155 bar) and temperature (280°C) conditions observed in a pressurized water reactor, so it can be used to study all the physical phenomena(7) involved in a reactivity accident, along with their interactions. The CIP program consists of ten tests on different types of fuel (UO2 or MOX) at different burnups, using different cladding materials. Among other things, the program will provide a fuller understanding of thermal and mechanical processes that are observed in the fuel rods and that can impair their integrity, in particular during the advanced phase of the accident.

Learn more: summary of the CABRI research program