Characterization of local multi-physics phenomena in the CABRI research reactor

The IRESNE R&D institute at CEA Cadarache invites applications for a post-doctoral position whose aim is first to develop a coupling between the APOLLO3®/THEDI core model at the pin-scale and the CATHARE model of the 3He depressurization system. Then, with the support of this simulation tool, the second objective will be to define core configurations of interest and measurements for characterizing local multi-physics phenomena in CABRI.
The CABRI pool-type research reactor located at CEA Cadarache is dedicated to the analysis of nuclear fuel behavior during Reactivity-Injection Accident (RIA) in Pressurized Water Reactors. The reactor experimentally simulates power pulse transients in the driver zone, which induces a RIA-representative energy deposition in the fuel sample of a water-loop at the core center. The power transients in the CABRI core are initiated by the depressurization of transient rods containing a strong neutron absorber, 3He.
Two models have been recently developed to simulate CABRI power transients. The first model at the assembly scale is a tool called PALANTIR, based on the CATHARE2 system thermal-hydraulics code with additional surrogate models to take into account the reactivity injected by 3He depressurization. The CATHARE2 code includes a neutron point kinetics module, a heat equation solver module and simplified thermomechanical models for fuel pins. In addition to the core, the depressurization circuit is modeled, providing access to 3He density in the transient rods.
The second model, at the pin-scale level, is based on a APOLLO3®/THEDI coupling via the C3PO platform. APOLLO3® solves the simplified transport equation. THEDI is used to model an unsteady 1D two-phase hydraulics flow in the core. It also solves the 1D heat equation for fuel thermics. For the simulation of each power transient in CABRI, PALANTIR provides the 3He density evolution versus time; these data are imposed as boundary condition in the APOLLO3®/THEDI coupling.

Innovative strategies for minor actinides using molten salt reactors

Within the framework of the ISAC (Innovative System for Actinides Conversion) project of the France Relance initiative, preliminary concepts of molten salt reactor capable of incinerating minor actinides have to be proposed in connection with prospective évolutions of the French nuclear fleet (stabilisation or reduction of the plutonium and americium inventory, minimization of the deep storage footprint, …) and contraints linked to the nuclear fuel cycle (plutonium and minor actinides inventories). The specificities of molten salt reactors will be exploited to design innovative transmutation strategies.
The postdoctoral fellow will be based in the reactor and fuel cycle physics unit of the IRESNE R&D institute at CEA Cadarache. He/she will develop expertise in neutronics, fuel physics, and in the design of Generation-IV reactors of the molten salt type.

Development of multiphysics tools dedicated to the modeling of FSR and associated studies.

The sodium group of DM2S (department of CEA Saclay) develops numerical coupling tools in order to realize accidental case studies (fast transient). The physical domains concerned are neutronics, thermo-hydraulics and mechanics. The subject of this post-doc deals within this framework.
The aim is to carry out several studies: the integration of a coupling within the CORPUS platform, to carry out studies in order to test (and introduce) in the coupling the impact of the deformation of the assemblies by the Temperature on the flow of liquid sodium, the use of the neutronic cross sections generated by the code APOLLO3, the study of other accidental cases, and extend the modeling to the subchannel and pin scales.

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