Worldwide electricity consumption is constantly increasing, regardless of progress in efficiency of transmission or reduction of energy needs in industry. Even though the global role of nuclear energy is decreasing in the electricity mix, it continues to have an important share: from 2000 to 2019Statistical Review of World Energy
https://www.bp.com/en/global/corporate/energy-economics/statistical-review-of-world-energy.html the worldwide percentage of nuclear electricity dropped from 14.6% to 10.4%, while the total electricity increased by 75% and the nuclear electricity production increased by 8.7%. The strategic objectives in nuclear energy are safety aspects, spent fuel and high-level waste management and disposal, developing next generation reactors with more efficient fuel use (less waste), preparing the experimental phase of ITER, and continuing the engineering design of a fusion DEMOnstration reactor.

The strategic objectives in nuclear energy are safety aspects, spent fuel and high-level waste management and disposal, developing next generation reactors with more efficient fuel use (less waste), preparing the experimental phase of ITER, and continuing the engineering design of a fusion DEMOnstration reactor.

Current Status

NUCLEAR FISSION Nuclear fission plays an important role to provide a stable, base load electricity in the EU (about 25% in 2018Nuclear Power in the European Union – World Nuclear Association
https://www.world-nuclear.org/information-library/country-profiles/others/european-union.aspx). The main strategic objectives are safety aspects and long-term waste disposal. In the field of Accelerator Driven Systems which could be used for transmutation of long-lived actinides, a staged approach was adopted by MYRRHA, leading to the full realisation of the facility by 2036. MYRRHA is part of an overall approach18Hamid Aït Abderrahim et al. Partitioning and transmutation contribution of MYRRHA to an EU strategy for HLW management and main achievements of MYRRHA related FP7 and H2020 projects: MYRTE, MARISA, MAXSIMA, SEARCH, MAX, FREYA, ARCA. EPJ Nuclear Sci. Technol. 6, 33 (2020)
https://www.epj-n.org/articles/epjn/pdf/2020/01/epjn190057.pdf – Partitioning & Transmutation (P&T) – to reduce the amount of waste that requires geological repository. Moreover, by recycling and reusing the fissile materials and minor actinides contained in the spent fuel, P&T decreases the need of fresh raw materials. While recognizing the high scientific value of the project, the Forum decided not to award to MYRRHA the status of Landmark in 2021, expecting in the next few years a stronger case for implementation, especially since the creation of an AISBL – International non-profit Association under Belgian Law – in September 2021. While the approach rests on the two legs, Partitioning and Transmutation, the field of Partitioninge.g. partitioning of spent fuel from the Experimental Breeder Reactor was performed at Idaho National Laboratory using pyro-processing method
https://inldigitallibrary.inl.gov/sites/sti/sti/5411188.pdf is more mature. Therefore, the MYRRHA infrastructure, the scientific quality of which was fully recognized by the SWG evaluation, is needed in closing the fuel cycle as an approach to the problem of radioactive waste.

In many countries, lifetime extensions of existing Nuclear Power Plants (NPPs) need experiments on materials under ionising radiation. Here, the ESFRI Landmark JHR plays a significant role. High-performance computing (HPC) of material properties is also needed, which has great potential for a cross-fertilisation with other materials science in general and, in particular, in the field of nuclear fusion (see below).

In view of the ageing of NPPs, as well as the nuclear phase-out by some, decommissioning and radioactive waste management – with the related safety, economic and environmental aspects – are increasing in European, and several countries are accumulating experience. This is a field that, in the future, could benefit from a dedicated RI.

In the Sustainable Nuclear Energy Technology Platform (SNETP)Sustainable Nuclear Energy Technology Platform (SNETP)
https://snetp.eu/ , within its ESNII branch, the use of process heat and cogeneration are relevant topics (NC2I branch). Therefore, the GEMINI initiativeGemini Initiative
http://www.gemini-initiative.com/ was dedicated to this topic. Small Modular Reactors (SMR), delivering up to about 300 MWe, are a new field of developmentExelon completes SMR feasibility study for Polish programme – World Nuclear News
https://www.world-nuclear-news.org/Articles/Exelon-completes-SMR-feasibility-study-for-Polish. Besides improved safety features, SMR are getting serious attention for district heating, where a major impact on CO2 emissions can be expectedGood riddance to fossil fuels! VTT develops a Small Modular Reactor for district heating
https://www.vttresearch.com/en/news-and-ideas/good-riddance-fossil-fuels-vtt-develops-small-modular-reactor-district-heating. Hydrogen production is another subject of R&D, with an interconnection with Concentrating Solar Power. This is clearly a development with great potential for new business opportunities for the nuclear industry. The role of nuclear energy is greatly affected by public perception of related risks and benefits. Therefore, more cooperation with Social Sciences is needed, offering a clear interconnection with this other ESFRI domain.

Therefore, it can be seen how the fission field can give a contribution to the goals of CO2 emissions reduction. Moreover, it has clear interconnections with HPC and material studies, as well as with Social Sciences, features that it shares with the fusion field.

NUCLEAR FUSION The European fusion programmeThe EUROfusion programme – EUROfusion
https://www.euro-fusion.org/programme/ has two main objectives, to prepare for the successful operation of ITERITER
https://www.iter.org, the first fusion device to create net energy, and to design the first power-producing facility, so-called DEMO, scheduled to be operational by the mid of the 21st century. Construction of ITER is in full speed, with a first plasma by 2025 and the D-T operation by the end of 2035. In addition, EUROfusion coordinates the use of all the main European fusion research facilities.

Within EUROfusion, two different reactor concepts are explored: tokamaks and stellarators. The tokamak-line of research has in the past produced superior plasmas and, thus, five tokamaksASDEX-Upgrade (Max Planck institute, Garching, Germany), JET and MAST (CCFE, Culham, U.K.), TCV (EPFL, Lausanne, Switzerland) and WEST (CEA, Cadarache, France) are currently in operation. The JET tokamak in the UK, the only one with the ability to operate with D-T mixture and, thus, pivotal in the scientific preparation of ITER, will remain at disposal of the EU community, as the UK will stay in Euratom. In the framework of the Broader Approach (BA) AgreementThe Broader Approach agreement between Japan and EURATOM covers many other activities.
https://www.ba-fusion.org/ba/, EU and Japan have completed the construction of JT-60SAAdvanced Superconducting Tomawak JT-60SA
https://www.jt60sa.org, a superconducting JET size tokamak with some novel technologies (e.g. the 500 keV negative neutral beam). It will be jointly exploited starting this year and will contribute to the many key physics issues of interest for ITER. In addition, to study the crucial issue of power and particle exhaust in a reactor, a dedicated device, the Divertor Tokamak Test (DTT)DTT DIVERTOR TOKAMAK TEST facility
https://www.dtt-project.it/ facility will be constructed in Frascati, Italy, with first experimental plasma expected in 2026. EU is hosting and exploiting jointly with ITER the Neutral Beam Test Facility (NBTF) in Padua, ItalyNeutral Beam Test Facility (NBTF)
https://www.iter.org/construction/NBTF.

The stellarators are attractive since they have intrinsically a steady state plasma. However, the confinement properties of stellarators have been inferior to those in tokamaks. HPC optimization of the magnetic configuration led to the construction of the Wendelstein 7-X (W7-X)Wendelstein 7-X
https://www.ipp.mpg.de/w7x stellarator in Greifswald (Max Planck institute for Plasma Physics). The first experimental campaigns, started in 2016, have even exceeded many of the initial goals, sparking hopes. Thus, even in the DEMO design, the option for a stellarator device is kept open.

The ongoing EUROfusion in Horizon Europe (2021-2025) has a strong component on the DEMO design with two main goals: i) to produce a substantial amount of electricity, and ii) to be self-sufficient in tritiumTritium, a « fuel » of the fusion reactor does not exist in nature and must be produced by the fusion reactor itself, if one considers an industrial deployment of fusion electricity.. For the operation of ITER, a flight simulator is under preparation. A strong emphasis is on theoretical/numerical work for extrapolation to DEMO through the E-TASC initiative (EUROfusion Theory and Advanced Simulation Coordination), opening up new possibilities for fusion plasma simulation and for related materials science.

A fusion reactor requires materials that tolerate neutron irradiation. Within the BA, commissioning of the first components of the neutron source prototype IFMIF-EVEDA LIPAc installed in Rokkasho, Japan is under wayFMIF/EVIDA
https://www.ifmif.org/. The EUROfusion programme supports IFMIF and proposes the ESFRI Project IFMIF-DONES as an interim step.

Therefore, the fusion program is based on an international collaboration and competition, involving several countries outside of the EU, and is based on a solid roadmap with well-defined objectives and clear interconnections with HPC and material studies.

CROSS-CUTTING ISSUES BETWEEN FISSION AND FUSION Materials research is the most prominent common topic to fission and fusion. For fission it is a key element for the prolongation of NPP operation. For fusion, it is crucial for the construction of a fusion reactor. The field of experimental investigation and numerical simulation are cross-cutting fields, while another is the development of accelerators to be used in ADS for fission and in a neutron source for fusion material irradiation. Both fusion and fission need to involve specialists in Social Sciences and Humanities to create good contacts and paths of communication with society. Collaboration with social sciences is important to understand the public opinion towards a highly complex and emotional topic such as nuclear energy. The role of nuclear power in transitioning from the fossil fuels should be analyzed by socio-economic approaches combined with technological ones.

GAPS, CHALLENGES AND FUTURE NEEDS

Several gaps have been identified: i) decommissioning and waste disposal of aging NPPs would benefit from a dedicated RI; ii) experimental effort on SMR should be intensified; iii) for fusion, the issue of material development requires to go from the Preparatory Phase to the Implementation Phase of the ESFRI Project IFMIF-DONES. A clear future need concerns disposal of nuclear waste produced in power plants. This concerns both countries abandoning and countries continuing with nuclear power. So far only Finland is constructing geological deposition, and there is an obvious need for reducing the amount of long-term radioactive waste EU-wide. The MYRRHA infrastructure could address this need but, at the time of writing of this report, is still working to procure the necessary financial commitments from additional partners for its full implementation.

In general, it may be advantageous for the EU to enhance international cooperation and to make a stronger effort to attract private financial resources into energy R&D&I.

Research on nuclear energy for deep space exploration is another sector worth of consideration for the EU. So are various applications of nuclear technologies with cross-cutting aspects with PSE, like for instance antineutrino detectors sensitive to reactor power and fuel changes.

While the role of renewable sources will be crucial in the long-term, during the transition period it will be necessary to support a broad range of R&D&I covering different ways of energy production including nuclear.

As research on nuclear energy is linked to national policies on the use of nuclear generated electricity, the above considerations of the research goals in this area do not engage, in any ways, national financial or political commitments.