Reference : UMR5821-CHRVEL-120
Workplace : GRENOBLE
Date of publication : Wednesday, June 22, 2022
Scientific Responsible name : The thesis supervisor will be Elsa Merle (CNRS/Grenoble INP) and he/she will be co-supervised by Gérald Senentz and Léa Tillard (ORANO), and Axel Laureau (CNRS).
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 20 October 2022
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Molten salt nuclear reactors (MSRs) have great potential in terms of safety and flexibility. These are reactors in which the fuel is dissolved in a mixture of molten salts (liquid), acting also as the coolant. The salt circulates in the fuel circuit through an area called the "core" where it is made critical by geometry, producing heat, which it extracted by passing through a heat exchanger, thus allowing the energy produced to be used, either in the form of heat (heat-generating role) or electricity (power-generating role). This type of reactor is characterized by its intrinsically core stable behavior, and its versatility (choice of cycle, choice of neutron spectrum, choice of salt composition, etc.) and therefore the versatility of its applications (power reactor on a range from very small to very large power, burner of high activity and long-life waste by transmutation, etc.). As these qualities are sought after in the current nuclear context, it is attracting renewed interest in France, in Europe and in the world.
For about twenty years, the CNRS, through the MSFR (Molten Salt Fast Reactor) team of LPSC (Laboratoire de Physique Subatomique et de Cosmologie), has been studying this type of reactor in various forms, and in particular the so-called reference MSFR, a large power breeder reactor operating in the Thorium cycle and with a fluoride salt, as well as a new version of regenerative reactor this time in the U/Pu cycle and chloride salt studied within the framework of the European project SAMOSAFER in progress and subject of the PhD thesis of Hugo Pitois. Finally, the LPSC MSFR team has been working in collaboration with ORANO on molten salt reactors as actinides converter for 4 years, in particular via the current PhD thesis of Laura Mesthiviers.
Given the clear renewed interest in this promising technology, new collaborations have been set up, and new studies are in progress, in particular those around MSR concepts in chloride salts converting actinides, including the ARAMIS (Advanced Reactor for Actinides Management in Salt) reactor led by the CEA and studied within the framework of the national ISAC (Innovative System for Actinides Conversion) project which began in the first half of 2022 and whose partners are: CEA, CNRS, ORANO, EDF, FRAMATOME. The ISAC project aims to study the ability of a breakthrough technology, here MSRs, to reduce the inventory of actinides from the existing fleet via the transmutation of minor actinides, and this by carrying out an outline study (evaluation of design options, performance of the concept, analysis of operation and safety for both the reactor and its fuel cycle) and by associating it with the first small-scale experiments on the main locks in this sector: the chemistry of salts, treatment/recycling, the prevention of corrosion applied to materials components of the primary circuit. Scenario studies will be associated in order to assess the final impact on the inventory and the type of waste to be stored according to different hypotheses.
Molten salt reactors are also at the heart of the new European project MIMOSA (MultI-recycling strategies of LWR SNF focusing on MOlten SAlt technology) led by ORANO, starting in June 2022 and of which CNRS is partner, implied in particular in the Working Groups 1 ( Multi-recycling scenarios analysis) and 3 (Molten Salt composition evolution in reactor). The MIMOSA project considers the impact of the introduction of molten salt reactors (preferably using chloride salt) on the fuel cycle at European level, with both breeder and actinide converter concepts in symbiosis with the current fleet of nuclear reactors under operation.
The subject of the PhD thesis proposed here will include contributions half to the national ISAC project and half to the European project MIMOSA, on calculations in neutronics, reactor physics and safety, as well as fuel cycle studies of MSR deployment in different reactor fleets needing the development of a scenario code. The beginning of the thesis work will relate to the development of a new version of the SDF/ISF scenario code developed and used in the LPSC MSFR team for twenty years, then if necessary, to the introduction of molten salts reactors in a simplified form in an existing dynamic fuel cycle simulation tool. Deployment studies will then be carried out with these codes, in parallel with neutronic evolutionary calculations carried out with the REM code (reference to date for evolution calculations of molten salt reactors) in order to characterize and optimize cores of MSR in connection with their deployment. The PhD student may also contribute to other studies, depending on the progress of the thesis and the MIMOSA and ISAC projects, in particular in connection with the design and safety studies of these reactors: behavior of the core in normal and accident situations, analyses of reactor starting and shut down phases, participation in the risk analysis in collaboration with EDF and Framatome.
The thesis supervisor will be Elsa Merle (CNRS/Grenoble INP) and he/she will be co-supervised by Gérald Senentz and Léa Tillard (ORANO), and Axel Laureau (CNRS).
The candidate must have a Master's degree in nuclear or reactor physics or equivalent. He or she must:
- Have a good knowledge of reactor physics (neutronics, thermal-hydraulics, safety, fuel chemistry...)
- Have a good knowledge of the use of evolving neutronic codes and scenarios codes
- Be able to work in a team in the context of a wide range of collaborations
- Be used to developing computer code, especially in Python, C++ and Java
- Ability to produce large amounts of data
- Fluency in French and scientific English, both spoken and written
- Be rigorous: know how to report, respect deadlines.
The doctoral student under CNRS contract will be based at the LPSC in Grenoble with occasional missions at Orano in Châtillon. The research work will be multidisciplinary, from reactor physics and scenarios to safety analysis.
The Laboratory of Subatomic Physics and Cosmology of Grenoble (LPSC) (http://lpsc.in2p3.fr) is a joint research unit associating CNRS-IN2P3, the University of Grenoble Alpes (UGA) and Grenoble INP, for an average staff of about 230 people.
The PhD student will be assigned́(e) to the MSFR Team composed of 3 LPSC staff (1 professor, 1 research fellow and 1 research director emeritus) and will be placed under the direct hierarchical authority of the team leader (E. Merle).
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