• Organisation: European Commission
  • Institute: Directorate for Nuclear Safety and Security (Karlsruhe)
    JRC.G.I.3 Nuclear Fuel Safety Unit
  • Location: Karlsruhe, Germany
  • Contract: Trainee
  • Duration: 5 months
  • Deadline: 07/01/2018 23:59 Brussels time

As the science and knowledge service of the Commission, the mission of DG Joint Research Centre is to support EU policies with independent evidence throughout the whole policy cycle.

A traineeship is proposed to perform and analyse original experimental measurements of radiance emission spectra from laser-heated corium crust simulants.

In the past years, there has been growing interest for in-vessel corium retention (IVR) as a severe accident management strategy, in order to meet the stringent safety requirements for Generation III nuclear power plants as well as to enhance the safety features of currently operating Gen-II reactors in the wake of the Fukushima accident.

Demonstrating the feasibility of in-vessel retention requires knowledge of the heat fluxes at the boundary of the melt pool. There is, however, very little data available on the radiative properties of the upper solid/liquid layer. In particular, the emissivity of the corium crust has a direct influence on the heat diffusion mechanisms leading to the so-called “focusing effect”. Although the latter is an essential phenomenon determining the viability of IVR, there have not been any measurements of this emissivity under an oxidizing atmosphere, and the impact of the presence of uranium, zirconium or oxygen on the emissivity has not been studied yet.

The proposed traineeship project aims at providing new data on the emissivity of the upper corium layer under different atmospheres. An already well-established laser-heating technique coupled with fast multi-wavelength pyrometry will be used for the first time in this challenging research field. Experimental data obtained on selected prototypical compositions will be analysed and interpreted with the help of additional material characterisation techniques, such as X-ray diffraction, electron microscopy and Raman spectroscopy. They will be used in the light of broader severe accident research activities, involving also large international projects such as SAFEST and TCOFF.

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