FIDES-II meeting participants in Mol, Belgium. Photo courtesy of SCK CEN
Members of the NEA’s Second Framework for Irradiation Experiments (FIDES-II) joint undertaking gathered on 20-24 April in Mol, Belgium, for the Technical Advisory Group and Governing Board meetings hosted by the Belgian Nuclear Research Centre SCK CEN. 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 Programmes, JEEPs. The latest FIDES-II meeting gathered 70 on-site and 15 online participants, with members of the consortium coming from 14 countries and the European Commission.
Marking its fifth anniversary, FIDES-II has delivered high-impact experimental results, underpinned by a strong suite of supporting activities - spanning state-of-the-art modelling and simulation, advanced instrumentation, and aiming for rigorous data management and quality assurance systems - ensuring both scientific depth and operational reliability. Throughout the five years, FIDES-II has provided a platform for experts in fuel and materials development, with momentum continuing to build as the FIDES-II Governing Board approved an expanding portfolio of experiments for the second term of the Framework and a growing network of research reactors joins the initiative.
The main focus of the meeting was the review of the progress 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;
- ATOMIC to investigate various novel fuel forms;
- INCREASE phases 1 and 2 to irradiate light water reactor structural materials; and
- HITEC to irradiate advanced reactor structural materials.
First irradiations of cladding materials and reactivity tests for fuel have been performed in previous years, and during 2025 several in-reactor experiments have been concluded. The online results of the second high-burnup test performed at TREAT reactor were presented in the meeting, as well as those of several other recently conducted experiments, including P2M instrumentation qualification test and recently finished first batch of ATOMIC irradiation.
In addition to the review of ongoing projects, participants discussed the programme of work for the next term of FIDES-II, starting in April 2027. The review of Technical Advisory Group had produced a ranked list of proposals, which had been molded into several alternative scenarios for future programme of work. These scenarios were discussed and decided on by the Governing Board.
The Framework has several cross-cutting activities that are carried out concurrently to the experiments. One major collaborative action has been working on experiments’ instrumentation, as experts from different reactors have gathered to share experiences and support each other on solving challenges relating to instrumenting nuclear experiments. An instrumentation workshop focusing on thermocouples was held on the margins of the FIDES-II meeting.
The week included a technical visit at SCK CEN, where the participants toured various sites including the BR2 reactor, LHMA hot cells, and experiment manufacturing workshop.
FIDES-II Governing Board Chair Peter Ungelenk hands to SCK CEN Director General Peter Baeten the FIDES plaque commemorating the value of BR2 research reactor to international nuclear community. Photo courtesy of SCK CEN
