Material Testing Reactors have been for many decades key research tools for fuel and material behaviour studies under neutron flux supporting nuclear industries, research institutes and regulators. Whatever the progress in simulation, MTRs will remain a necessity for the qualification of new fuels and materials under irradiation notably in support to safety demonstration. Currently, in response to this need, the Jules Horowitz Reactor (JHR) is under construction. The JHOP2040 proposal presents a Coordination and Support Action aiming to 1) bring together with the JHR consortium of key actors, all relevant European nuclear research associations and member states that are not represented in the JHR consortium and 2) to produce strategic research roadmaps for the operation of the JHR. These roadmaps will cover both the first 4-year programme period and the following 11 years of operation. The outcome of JHOP2040 will be financial and programme model for Euratom taking into account also the governance and cost breakdown of the programmes. JHOP2040 will strengthen and widen the JHR research network by bringing together relevant stakeholders and interest groups to identify and review their current and future needs for fuel, material and technology issues within and outside of the current JHR consortium. Extensive utilization of the JHR via Euratom access rights and full use of the planned JHR capacity by promoting and enhancing the collaboration between potential users is the ultimate goal. The main advantage of this proposal is that all European partners of the JHR consortium are behind the proposal and several EU member states outside the JHR consortium and European institutions have expressed already their interest in being involved in the roadmap work. Important part of the proposal will be the communication with EU member states via JRC. JHOP2040 will have a close connection to the NFRP-08 CSA in this same call.

While the scientific understanding of the dissolution of standard spent uranium oxide fuel has reached a certain mature state, new types of fuels with additives (“doped fuels”) have been developed. These fuels are already in use in some reactors, and their use is foreseen to be expanded. Dissolution data is now required to confirm that the dissolution behaviour of such fuels in a geological repository environment is similar to that of standard fuel. Similarly, there is a dearth of dissolution data from MOX fuels, which are also currently in use in several reactors. This project is therefore targeting oxide fuels containing additives, including Cr, Gd and Pu, in order to ensure that relevant characteristics are understood to a level commensurate with standard fuels. This project aims to expand the database on spent fuel dissolution with results from dissolution studies performed in truly reducing conditions, with hydrogen present. The effects of dopants will be investigated through experiments using both spent nuclear fuel and synthetic materials specifically designed for the project. In addition, chemical modelling will be employed to improve the understanding and description of the dissolution process relevant to the expected chemical conditions inside a failed waste container in a deep geological repository environment.