Our research
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IRESNE is targeting part of its research on the development of small modular reactors.​

Our research for the NUWARDTM industrial-scale project
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Under our collaboration on the NUWARDTM project with EDF, Naval Group and TechnicAtome, scientists at the Research Institute for Nuclear Systems for Low-Carbon Energy Production (IRESNE) are pooling their expertise and knowledge in various fields of research that concern the project.

  • Core neutronic studies:
    Scientists tasked with researching SMRs are particularly focusing on neutron studies and developing calculation code packages specifically for SMRs. For instance, the control rods play an important role in SMRs because this reactor design uses no soluble boron. This is why we must investigate their characteristics and interactions during reactor operation and shutdown. The teams are able to develop images of the core, loading plans and reactor control diagrams that meet the requirements of the NUWARDTM nuclear steam supply system (NSSS).

  • Pre-conceptual design of the passive systems’ architecture:
    An advantage of the small modular reactor design is that passive safety systems can be integrated with greater ease owing to their small size and their lower level of decay heat. For this reason, our teams are studying and developing smart architectures that can easily integrate innovative systems within the reactor block, thereby ensuring several days of autonomous operation in accident conditions.

  • Severe accident scenario studies:
    Strengthened by our studies on higher-power reactor units, our scientists already have expertise in modelling severe accidents and calculating source terms. These computer models can be used to study corium retention in the reactor vessel and the transport of fission products. The teams at the institute are now taking these previous studies further to adapt them to SMR conditions.

  • New test facilities for SMR research:
    Research on this new reactor type - more specifically NUWARDTM - calls for new experimental means to test and qualify the innovative components comprising the key systems that make this technology so advanced. This means that part of our test platforms meet our experimental requirements while we work on designing and developing new experimental loops to test innovative technical improvements such as compact steam generators and passive core cooling systems. Specific new tests that are highly instrumented have also been designed by our experts to study the physical mechanisms that lead to natural convection in single- or two-phase conditions.

  • The most recent versions of our scientific computing tools:​
    Tests in the experimental loops are used to validate scientific computing tools such as the CATHARE-3 thermohydraulic code developed by experts at the CEA. More specifically, new targeted and highly instrumented tests have been designed by our experts to study the physical mechanisms that lead to natural convection in single- or two-phase conditions. These refined characterisation tests focus on the phenomenology of passive systems, which should improve and validate the CATHARE-3 models needed for the NUWARDTM safety case. At the same time, studies are gradually turning towards the new reference tool for neutronic studies called APOLLO3 This computing tool is currently undergoing digital validation so it can be used to better describe the specific behaviour of the core without soluble boron but with significant quantities of burnable poisons and control rods present in the core during operation. ​​

​Sunrise in Greece

Research on SMRs for purposes other than electricity generation
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SMRs can be used for applications that fall outside the scope of electricity generation. They are capable of providing electricity and heat to produce hydrogen, fresh water; the heat they generate can also be exploited for industrial purposes, or to power domestic heating systems, etc. These new applications are the subject of exploratory research carried out by our scientists.

  • Pre-conceptual designs for low-power heat-producing SMRs:
    In response to these new demands, our teams are working on pre-conceptual designs for low-power heat-producing SMR concepts that can operate at low temperature and pressure, thereby greatly simplifying the nuclear components needed for the reactor systems. Three pre-conceptual designs are currently under development; they differ by their architecture, the resulting water temperatures, their core sizes, and their cycle lengths. These design processes include both technical and economic studies to make sure they are capable of meeting heat production needs while being economically feasible.

  • Optional studies on heat storage:
    To further improve their cost-effectiveness, power SMRs could be connected to heat storage systems to provide district heating upon demand, for instance, while prioritising operation at nominal power.

  • SMRs and high-temperature electrolysis:
    A proven method could be exploited to produce hydrogen, i.e. water electrolysis. A process developed by the CEA’s LITEN laboratory, which operates at high temperature, has been shown to provide a higher energy efficiency that conventional electrolysis processes performed at low temperature.
    Together with the LITEN, our teams are investigating power conversion systems that couple SMRs operating in combined heat and power (CHP) mode with high-temperature steam electrolysis (HTSE). This process necessitates both electricity and heat. Different direct and indirect methods of coupling are being considered, as well as different heat extraction methods on the SMR side and methods of recovering residual heat on the HTSE side. These studies show that SMR-HTSE coupling concepts can improve the overall efficiency of the facility.

  • Modelling power conversion system (PCS):
    To assess the technical performance of hybrid systems combining SMR power, heat storage and HTSE, our experts are developing a tool to model the multi-source energy conversion system. When coupled with already proven computing packaging, this modelling tool will allow us to study the operation of hybrid systems taking into account the intermittency of electricity grids and heat distribution systems.​​