Experimental study of the effect of molybdenum on iodine transport in the primary circuit during a severe nuclear power plant accident

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    Abstract

    In case of a severe accident in Light Water Reactor (LWR), radioactive iodine may be released into the environment, impacting significantly to the source term. Determination of the amount released, and of the physical state of iodine (gaseous form or solid aerosol form), is thus a major issue, regarding the improvement of the accident management and mitigation measures The experimental EXSI-PC facility has been specifically designed and built to investigate the behaviour of iodine containing fission product deposits on primary circuit surfaces during a severe nuclear accident. Studies were conducted with two mixtures of caesium iodide and molybdenum oxide (Mo/Cs=1.6 and Mo/Cs=5) in order to assess the possible chemical reactions and the effect on the transport of chemical species through the primary circuit. In addition, two carrier gas compositions (Ar/H2O versus Ar/Air) were studied to highlight the effect of oxygen partial pressure. In this work, the influence of molybdenum presence on the caesium iodide behaviour under two atmospheres: Ar/H2O and Ar/Air (86.7/13.3 vol.%) was studied. The release of gaseous iodine was higher when the oxygen partial pressure was higher (i.e. for Ar/Air atmosphere). In addition, the results showed that an initial Mo/Cs molar ratio of 1.6 produced about 1.5 times higher amount of gaseous iodine than a ratio of 5. The formation of caesium molybdates was identified in the crucible after the experiments, confirming that the reaction between caesium and molybdenum is the reason for the observed formation of gaseous iodine. The experimental results are mostly in accordance with the equilibrium calculations performed with FactSage.

    Original languageEnglish
    Title of host publicationProceedings of the 2018 International Congress on Advances in Nuclear Power Plants, ICAPP 2018
    PublisherAmerican Nuclear Society ANS
    Pages293-301
    Number of pages9
    Volume1
    ISBN (Print)9781510861206
    Publication statusPublished - 1 Jan 2018
    MoE publication typeNot Eligible
    Event2018 International Congress on Advances in Nuclear Power Plants, ICAPP 2018 - Charlotte, United States
    Duration: 8 Apr 201811 Apr 2018

    Conference

    Conference2018 International Congress on Advances in Nuclear Power Plants, ICAPP 2018
    CountryUnited States
    CityCharlotte
    Period8/04/1811/04/18

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  • Cite this

    Gouëllo, M., Hokkinen, J., & Kärkelä, T. (2018). Experimental study of the effect of molybdenum on iodine transport in the primary circuit during a severe nuclear power plant accident. In Proceedings of the 2018 International Congress on Advances in Nuclear Power Plants, ICAPP 2018 (Vol. 1, pp. 293-301). American Nuclear Society ANS.