Meeting participants gather in Idaho. (Photo: OECD NEA)
Members of the OECD Nuclear Energy Agency’s Second Framework for Irradiation Experiments (FIDES-II) joint undertaking gathered from September 29 to October 3 in Ketchum, Idaho, for the technical advisory group and governing board meetings hosted by Idaho National Laboratory. The FIDES-II Framework aims to ensure and foster competences in experimental nuclear fuel and structural materials in-reactor experiments through a diverse set of Joint Experimental Programs (JEEPs).
On the agenda: First irradiations of cladding materials and reactivity tests for fuel have been performed in previous years, and several in-reactor experiments took place in 2025. The online results of the first high-burnup test performed at INL’s TREAT reactor were presented to about 100 meeting participants from 14 countries and the European Commission. Participants also discussed several other recently conducted experiments.
The focus of the meeting was the review of the process of the ongoing JEEPs. The second three-year term of the framework, which started in April 2024, has nine ongoing JEEPs:
- P2M—aiming to perform power ramp experiments.
- HERA and LOC-HBU—performing accident simulations.
- INCA and MCA-ATF— studying irradiation creep with cladding irradiations.
- ATOMIC—investigating various novel fuel forms.
- INCREASE phases 1 and 2—irradiating light water reactor structural materials.
- HITEC—irradiating advanced reactor structural materials.
The FIDES-II meeting also included discussions of the program of work for the next term of FIDES-II, which will start in April 2027. The proposals for the third term were discussed, and a competitive process to review and rank them during the next half-year was decided on.
Additional testing: The framework has several cross-cutting activities that are carried out concurrent with the experiments. Modeling and simulation activities are actively pursued within projects, with the exercises using nonproprietary data also open to participants outside of FIDES-II community. Simulation exercises on ramp tests, reactivity insertion transients, and loss of coolant experiments under JEEPs P2M, HERA, and LOC-HBU have been recently finalized. More than 10 organizations have been involved in each of these exercises, and these represent significant additional value to the experimental work, according to the NEA.
The week finished with a technical visit to Idaho National Laboratory, where the participants visited the Experimental Breeder Reactor-I and Advanced Test Reactor complex.
