General information
Organisation
The French Alternative Energies and Atomic Energy Commission (CEA) is a key player in research, development and innovation in four main areas :
• defence and security,
• nuclear energy (fission and fusion),
• technological research for industry,
• fundamental research in the physical sciences and life sciences.
Drawing on its widely acknowledged expertise, and thanks to its 16000 technicians, engineers, researchers and staff, the CEA actively participates in collaborative projects with a large number of academic and industrial partners.
The CEA is established in ten centers spread throughout France
Reference
2025-35545
Description de l'unité
Laboratory in charge of carrying out experimental R&D on the PLINIUS platform to simulate nuclear reactor severe accident materials. 20+ staff including 7 young researchers (MSc, PhDs, post-docs).
Position description
Category
Materials, solid state physics
Contract
Postdoc
Job title
Aerosol generation and transformation mechanisms during the fuel debris cutting at Fukushima Daiichi H/F
Subject
During Fukushima Daiichi nuclear reactor accident, several hundred tons of fuel debris (the mixture generated by the reactor core melting and its interaction with structural materials) have been formed. CEA is part to several projects sponsored by Japanese organizations aiming at mastering the risks due to aerosols generated by fuel debris cutting for the future Fukushima Daiichi dismantling.
The post-doctoral work objective is to exploit the large experimental database created thanks to these projects in order to study the generation and transformation mechanisms of these aerosols for both thermal and mechanical cutting. An important source of aerosol seems to be partial evaporation/condensation. A thermodynamic modelling shall be proposed, coupled with some kinetic effects. For mechanical cutting, aerosol analyses shall be compared to fuel debris block microstructure to quantify a preferential release of some phases.
Contract duration (months)
12
Job description
During Fukushima Daiichi nuclear reactor accident, several hundred tons of fuel debris (the mixture generated by the reactor core melting and its interaction with structural materials) have been formed. Japanese government plans to dismantle within 30 to 40 years Fukushima Daiichi nuclear power station, which implies recovering the fuel debris that were formed during these accidents.
CEA is participating within an ONET Technologies/ASNR/CEA consortium to several projects aiming at developing fuel debris cutting. Mastering the risks due to radioactive aerosols generated during these operations is one important aspect of this R&D. In this framework, CEA has fabricated fuel debris prototypes corresponding to chemical compositions that have been estimated for these severe accidents. The French consortium has collected and analysed aerosols produced during mechanical cutting as well as during high temperature heating simulating thermal cutting.
The aim of this postdoctoral research is to exploit this large experimental database to study aerosol generation and transformation mechanisms for both thermal and mechanical cutting. For thermal cutting, an important source of aerosol seems to be partial evaporation/condensation, close to fractional distillation, of many chemical species that are present in the fuel debris. A thermodynamic modelling shall be proposed, using the NUCLEA or TAF-ID databases, coupled with some kinetic effects.
For mechanical cutting, relations between the phases observed on the bulk samples and the observed aerosols will be considered in view of determining a phenomenological understand and in a second stage modelling it. Then, the observed of the cutting atmosphere (humidity, air vs. nitrogen) should be explained and its mechanisms could be quantified.
This postdoctoral work will start with a bibliographical study. In addition to the state of the art on aerosols produced by mechanical and thermal cutting, there shall be a comparison with the literature dedicated to radioactive aerosol release during severe accidents.
Then, a critical synthesis of the experimental results achieved by this French consortium will be carried out. The experimental database encompasses several fuel debris simulant block compositions (in- and ex-vessel fuel debris, with or without depleted uranium). It includes characterization of samples before the cutting processes as well as size and chemical characterization of released aerosols. This experimental database can be completed if needed by the chemical or crystallographic analyses of samples already in the laboratory but not yet analysed.
A last phase of this work would consist in developing a model of fuel debris aerosols generation and transformation phenomena, in particular, evaporation/condensation during thermal processes and/or agglomeration of aerosol particles.
Methods / Means
Large experimental database - Microstructural Analysis - ThermoCalc thermodynamic software - aerosol
Applicant Profile
PhD requested in material engineering, aerosol science, applied chemical thermodynamics or nuclear engineering.
Position location
Site
Cadarache
Job location
France, Provence-Côte d'Azur, Bouches du Rhône (13)
Location
Saint Paul lez Durance
Candidate criteria
Recommended training
Doctorat (Sciences de Matériaux, Science des Aérosols, Génie Nucléaire)
PhD opportunity
Non
Requester
Position start date
01/09/2025