Job offer

European Commission; France; Sur place; EUR 30 000 - 45 000; Plein temps

Résumé du poste

Une commission de recherche en physique en France est à la recherche d'un chercheur pour développer des méthodes de mesure des sections efficaces nucléaires, spécifiquement axées sur le plutonium 240. Le poste est à plein temps, basé à Bordeaux, et impliquera des expériences novatrices au laboratoire JRC-Geel en Belgique, en collaboration avec une équipe d'experts.

Qualifications

• Expérience dans la recherche en physique nucléaire.
• Capacité à effectuer des études de sensibilité et des préparations expérimentales.
• Connaissance des isotopes et de la physique des réacteurs.

Responsabilités

• Appréhender les codes de simulation et d'analyse.
• Participer aux activités du groupe ACEN et réaliser des expériences.
• Évaluer les incertitudes des données nucléaires sur le 240Pu.

Connaissances

Analyse

Simulation

Physique nucléaire

Formation

Diplôme en physique ou domaine similaire

Description du poste

Organisation/Company CNRS Department Laboratoire de Physique des 2 infinis - Bordeaux Research Field Physics Researcher Profile First Stage Researcher (R1) Country France Application Deadline 3 Jul 2025 - 23:59 (UTC) Type of Contract Temporary Job Status Full-time Hours Per Week 35 Offer Starting Date 1 Oct 2025 Is the job funded through the EU Research Framework Programme? Not funded by a EU programme Is the Job related to staff position within a Research Infrastructure? No

Offer Description

The student will be based at LP2i. A first part of the work will consist in the appropriation of the simulation and analysis codes, as well as the preparation of the experiment. He/she will also participate in the activities of the ACEN group: other experiments, instrumental developments, etc.

Sensitivity analysis studies [1, 2, 3] have been performed for different types of advanced nuclear systems, in particular for Generation-IV fast reactors. These studies indicate that an important reduction of the uncertainties on nuclear data is needed for many actinides, such as heavier mass Pu isotopes.

The 240Pu isotope is produced in the nuclear fuel of thermal or fast reactors by successive neutron captures and or decays. This isotope is the second most present Pu isotope (behind 239Pu), but the first non-fissile one. The 240Pu isotope is particularly unsuited for recycling in a thermal reactor, due to its non-fissile property. A more efficient burning via the fission process would occur in a fast reactor, where the harder fission neutron spectrum would better match the fission threshold. Sensitivity studies performed in recent years have shown the need to reduce the uncertainties in the fission cross-section for 240Pu in the fast region. Existing nuclear data on 240Pu(n,f) show discrepancies between databases and experiments up to 10% between 1 and 2 MeV. It is then very important to reduce this uncertainty to around 3-4%.

A fission cross section measurement is usually performed relative to a well known cross section like 235U(n,f) or 238U(n,f). This process induces very strong correlation with these cross section, and with all actinides cross sections measured in the same way. On the contrary, the proton recoil technic consists in performing measurement relatively to the 1H(n,n) cross section. This cross section is a primary standard, very well known, structureless, and which can be calculated with ab-initio calculations. In this technic the 235U or 238U target used as reference is replaced by a H-film (usually a plastic foil). The neutrons will scatter on H nuclei, and recoil protons will be emitted and easily detected. This technic has been used several times in the past by the ACEN group of the LP2i lab [4, 5]. It led to totally uncorrelated results with uncertainties around 3-4% (more or less the same order of magnitude than standard fission measurement).

One of the Challenge of such experiment is the availability of the fissile target, as actinide target with suitable properties are quite rare. Hopefully, several 240Pu targets have been manufactured in the JRC-Geel lab (Belgium) in 2010. One of these targets is still available in this lab. Preliminary calculations will have to be made to adapt the experiment to the properties of this specific target.
The experiment will be carried out in the MONNET facility in the JRC-Geel lab, which presents several advantages:
- can produce neutron in the 1-2 MeV energy range thanks to the use of tritium targets
- availability of the 240Pu target in the same lab, negating the paperwork and delays of radioactive target transportation
- expertise of the MONNET team on cross section measurement