Second Framework for Irradiation Experiments (FIDES‑II)
Joint project

The NEA Second Framework for Irradiation Experiments (FIDES-II) supports the fuel and material experimental needs of nuclear safety regulators, technical support organisations, research institutions and industry and safeguards experimental knowledge for future generations. FIDES-II connects a global network of research facilities to perform high-priority experiments through Joint ExpErimental Programmes (JEEPs).

Eight Joint ExpErimental Programmes (JEEPs) are included in the 2024–2027 FIDES-II programme of work, which cover a wide range of research needs:

  • Fast power transients (HERA and LOC-HBu), slow power transients (P2M) and steady-state conditions (INCA, MCA-ATF and ATOMIC);
  • Fuel performance testing of accident tolerant fuel (ATF) designs including coated claddings (INCA, MCA-ATF and HERA), high burnup fuel (HERA and LOC-HBu) and fuels for generation four (GenIV) reactors (ATOMIC)
  • Mechanical properties of structural materials for LWR (INCREASE Phase 1 and 2) and GenIV Reactors (HITEC);
  • Co-ordinated modelling efforts to complement experimental interpretation underway (P2M and HERA) and under discussion for additional JEEPs.



The safe, reliable and efficient operation of nuclear power plants requires nuclear fuel and materials (F&M) technology to evolve and for their performances to be optimised. Achieving this requires solid experimental evidence, which can only be obtained from test facilities with the ability to perform neutron irradiation under representative steady state or transient conditions. F&M test facilities are essential for:

  • validating safety margins, simulation tools, and demonstrating operational performance;
  • assessing material behaviour in the context of the long-term operation programmes;
  • developing advanced F&M.

However, the number of available test facilities around the world are in significant decline. In the past five years, several major research reactors that provided testing services for the nuclear community were shut down after over fifty years of service. These included the Halden reactor in Norway, the OSIRIS in France, the JMTR in Japan, the NRU in Canada, among others.

Regulators and their technical support organisations, research organisations, and the industry all require F&M testing capacities on an ongoing basis. Some recent experience of test facilities attempting to re-establish prior capabilities has shown that the process can be extremely costly and time-consuming, further emphasising the importance of preserving experimental know-how through on-going research activity. In particular, the know-how and availability of test facilities for loss-of-coolant accidents, reactivity-initiated accidents and power ramps, is crucial.


FIDES is a project that truly arose from the needs of the community. As early as 2018, the international community had identified an emerging need to strengthen the network of international research facilities capable of meeting the unique and challenging needs for nuclear fuel and material development. The permanent closure of the Halden Reactor in Norway in June 2018, a key research facility in the area of nuclear fuel and materials research, brought new urgency to the conversation. A series of meetings with international experts and decision makers was organised to discuss the needs and define a solution. It was through these meetings that the FIDES framework emerged.

  • “Workshop on Enhancing Experimental Support for Advancements in Nuclear Fuels and Materials”, Paris, France, 8-10 January 2018
  • “Workshop on Building Multinational Fuels and Materials Testing Capacities for Science, Safety and Industry”, Boulogne-Billancourt, France, 4-5 October 2018
  • “Workshop on Introduction to the Multinational NEA Framework for In-pile Fuel and Material Testing”, Boulogne-Billancourt, France, 4-5 March 2019
  • “Preparing the Kick-off of FIDES Joint ExpErimental Programmes”, Boulogne-Billancourt, France, 3-5 September 2019

Member Area (password protected)


Belgium, Czechia, Finland, France, Germany, Hungary, Japan, Korea, Netherlands, Spain, Sweden, Switzerland, United Kingdom, United States, European Commission (EC)

Project period



Member contributions to FIDES fees: EUR 13 Million

Work scope value: Approximately EUR 30 Million