Identifying Po-containing molecules in MYRRHA

  1. Identifying Po-containing molecules in MYRRHA

    15_MAT03 / Solid-state physics
    Promotor(en): S. Cottenier, A. Aerts / Begeleider(s): A. Van Yperen-De Deyne, M. Mertens

    At the Belgian nuclear research center SCK-CEN in Mol, the MYRRHA reactor is being developed (http://myrrha.sckcen.be). MYRRHA is a so-called “accelerator driven system” (ADS): a reactor that does require an external proton beam in order to sustain a fission reaction. This makes it impossible to have, for instance, a Fukushima-like meltdown: in case of problems the accelerator is turned off, and the fission reactions terminate spontaneously. An ADS can also be used for the transmutation of long-lived nuclear waste into short-lived waste.

    The nuclear fuel of MYRRHA will be cooled not by water, but by a liquid metal: a lead-bismuth eutectic (LBE). This coolant is simultaneously also the target material for the proton beam, which produces the additional neutrons to reach criticality.

    As an unwanted side effect, nuclear reactions in the coolant will also produce a small amount of polonium isotopes. Polonium Is highly radiotoxic, and it is therefore essential to know how polonium and polonium-containing molecules will behave in the reactor environment.

    The formation of polonium-containing molecules (and Te-containing variants as model systems) is being studied experimentally at the SCK-CEN and at the Paul Scherrer Institut in Villigen (Switzerland). An experimental technique called thermochromatography can identify the presence of Po-containing molecules and can determine their binding energy with several surfaces. When combined with mass spectrometry, the mass of these molecules can be measured as well. None of these methods, however, allows a full identification of the molecule. One needs to know the correct molecular species in order to design the proper filters to capture those noxious molecules. Therefore, in this master thesis project, ab initio simulations will be used to predict complementary information that will lead to an identification of the molecular species.

    Goal You will search the literature to find out which Te-containing molecules with elements available in the reactor environment are known to exist (Te is homologous to Po, and experiments often study Te instead of Po for safety reasons). You will use these known Te-molecules to build confidence in the validity of your ab initio predictions. In a second stage, you will consider the same molecular species, but now with Po instead of Te. You will predict their stability and will determine their adsorption energy on various surfaces. Comparison of your predictions with the data available from thermochromatography and mass spectrometry will allow you to identify which Po-containing molecules are likely to be present in the MYRRHA coolant.

  1. Study programme
    Master of Science in Engineering Physics [EMPHYS], Master of Science in Physics and Astronomy [CMFYST]
    Clusters
    For Engineering Physics students, this thesis is closely related to the cluster(s) modelling, nano, nuclear