Six nuclear reactor concepts – referred to as Generation IV - are being developed internationally, all of which operate at higher temperatures than today’s reactors and make significant advances in the sustainability, economics, safety, reliability and proliferation-resistance of nuclear technology.
The six reactor concepts currently being developed are gas-cooled fast reactor (GFR), lead-cooled fast reactor (LFR), molten salt reactor (MSR), sodium-cooled fast reactor (SFR), supercritical water-cooled reactor (SCWR), and high-temperature gas-cooled reactor (HTR). Most of the six systems employ a closed fuel cycle to maximise the resource base and minimise the high-level waste produced. SFR, LFR, GFR and MSR are fast neutron reactors (FNR), and HTR and SCWR operate with slow neutrons like the plants currently in operation.1
To coordinate this work in the European Union, the Sustainable Nuclear Energy Technology Platform (SNETP) set up a taskforce comprising research organisations and interested industrial partners as the basis of the European Sustainable Nuclear Industrial Initiative (ESNII), the aim of which is to address the need for demonstration of Generation IV FNR technologies, together with the supporting research infrastructures, fuel facilities and R&D work. ESNII was officially launched at the SET-Plan Conference in Brussels in November 2010, with the aim of promoting Europe’s leadership in the development of Generation IV FNR technology in support of the energy system decarbonisation targets set in the EU’s Strategic Energy Technology Plan (SET-Plan).
The safety of nuclear fission technologies, together with the management of spent fuel and radioactive waste, are the key short and medium term issues to be addressed in achieving the 2020 objectives for nuclear energy. Fast spectrum reactors with closed fuel cycles, involving partitioning and transmutation of Pu and minor actinides (Np, Am, Cm), allow a significant reduction in high-level nuclear waste radiotoxicity and volume, while at the same time extracting up to 50-100 times more energy than current technology from the same quantity of natural uranium. One of the goals for fast neutron reactors is to demonstrate that they are at least as safe, if not outperforming in safety terms, the last-generation of pressurized water reactors. In this respect the technical issues linked to the behaviour of fuel and structural materials under harsh operational conditions (temperature, mechanical loading, irradiation, coolant environment) are central for the development of the fast nuclear reactors.
In its Strategic Research and Innovation Agenda (SRIA)2, published in 2013, SNETP identified the key R&D activities needed to develop the FNR technologies for commercial deployment by 2040. In ESNII three priority technologies were identified: sodium-cooled fast reactors are viewed as the reference technology, as they have had more substantial technological and reactor operational feed-back; the SRIA also acknowledged that, as lead(-bismuth)-cooled fast reactor technology has significantly extended its technological base it can be considered a shorter-term alternative technology; finally, in terms of its current stage of technological development, gas-cooled fast reactor technology is considered a longer-term alternative. Based on these priorities, SNETP has set ESNII the specific goal of designing, licensing, building and commissioning the sodium-cooled fast reactor prototype ASTRID and the lead-bismuth-cooled flexible fast spectrum irradiation facility MYRRHA before 2025.
The ASTRID SFR in France will allow Europe to demonstrate its capability to master mature sodium technology with improved safety characteristics. In order to respond to societal demands for the highest safety and lowest waste, the ASTRID design is focusing on improved waste management and resource utilisation and achieving a safety level compatible with Western European Nuclear Regulators' Association (WENRA) standards for new nuclear builds. The associated R&D programme will increase the robustness of the ASTRID technology and make it possible to achieve the Generation IV goals of sustainability, safety, reliability, economics and proliferation resistance. The MYRRHA project, being implemented by the Belgian Nuclear Research Centre SCK-CEN, will operate a flexible fast spectrum irradiation facility for development of accelerator-driven systems (ADS) that can "burn" waste, and to support the development of technology for the three fast reactor systems (sodium, lead and gas). This project will also offer a wide range of interesting irradiation conditions for fusion material research.
In parallel with those two projects, SNETP emphasises in its ESNII Implementation Plan 2013-20153 that activities should be continued around LFR and GFR technologies. As regards LFR, the Advanced Lead Fast Reactor European Demonstrator (ALFRED) will focus on design activities typical for a critical power reactor connected to the grid, and research into lead as a coolant, addressing specific differences from lead-bismuth technology. Maximum synergies will be sought with the MYRRHA project to optimise resources and planning. For GFR, the V4G4 centre of excellence has been established to develop and implement an R&D effort into helium-cooled fast reactors, with a view to developing the technical capability to launch the gas-cooled demonstrator ALLEGRO. All FNR reactors will need dedicated experimental facilities to simulate operational conditions. To this end a dedicated project, ADRIANA (Advanced Reactor Initiative and Network Arrangement), has undertaken a comprehensive mapping and gap analysis of research infrastructures including proposals for new experimental facilities.
The performance of fuel and structural materials under harsh conditions (temperature, mechanical loading, irradiation, coolant environment) is central for the development of the fast nuclear reactors. A joint programme for nuclear materials (JPNM) under the auspices of the European Energy Research Alliance (EERA) has therefore been developed in support of ESNII. The EERA JPNM is developing methods to assess candidate materials’ behaviour under operating conditions (predictive capability), and innovative materials with superior performance and reliability in those demanding environments.
Internationally, this effort is supported by the Generation IV International Forum (GIF), a cooperative endeavour organized to carry out the R&D work needed for the next generation nuclear energy systems. The EU, represented by Euratom, with the European Commission’s in-house science service, the Joint Research Centre (JRC), acting as its implementing agent, is working with other GIF partners to perform pre-competitive R&D on key technologies likely to be implemented in future nuclear systems. The JRC also carries out experimental research, numerical modelling and simulation, and feasibility and engineering studies on innovative nuclear reactor systems in support of the JPNM, ESNII and Euratom contribution to the GIF.
This research includes materials and fuel performance assessment for innovative reactor systems, including advanced thermo-mechanical, corrosion resistance, and irradiation and environmental performance assessment of candidate materials. The JRC also works on design codes and standards, contributes to the development of codes-of-practice for advanced testing techniques, and provides the data management tools applied in Europe. In collaboration with European and international partners, often in the frame of Euratom Framework Programme projects such as SARGEN_IV, CP ESFR, LEADER, and ESNII+, the JRC has participated in and actively contributes to the development of tools and methods for the safety assessment of these future systems to achieve high safety standards in nuclear reactors and in the nuclear fuel cycle, for instance, through integrated reactor accident modelling in support of EU nuclear safety policy. Another key aim is to provide a scientific basis for the protection of European citizens against risks associated with the handling and storage of highly radioactive materials and the development of advanced fuel for innovative reactors. Activities in this area are divided into four core competences: basic actinide science and applications; safety of the nuclear fuel cycle; safeguards and nuclear forensics; and education and user facilities. By conducting this work, the JRC’s prime objectives are to serve as a reference centre for basic actinide research, to contribute to an effective safety and safeguards system for the nuclear fuel cycle, and to study the technological and medical applications of radionuclides/actinides.
This and other work carried out under the ESNII umbrella is expected to result in a significant increase in the sustainability and safety of nuclear energy by demonstrating the technical, industrial and economic viability of Generation IV fast neutron reactors. Consequently, this work is essential to ensure that nuclear energy will continue to make a significant contribution to the decarbonisation of Europe’s energy sector.
For more information:
1 Generation IV Nuclear Reactors
2 Strategic Research and Innovation Agenda
3 ESNII European Sustainable Nuclear Industrial Initiative Implementation Plan 2013-15