A Separate Effect Study of the Influence of Molybdenum on Iodine and Caesium Transport in the Primary Circuit in Nuclear Severe Accident Conditions

    Research output: Contribution to conferenceConference articleScientificpeer-review

    Abstract

    In case of a severe accident on a Light Water Reactor (LWR), iodine may be released into the environment, impacting significantly the source term. The understanding of the iodine release from the damaged reactor core and its transport in the different parts of the reactor up to the reactor containment, is thus a major issue. The analysis of the Phébus-FP tests brought the hypothesis that iodine keeps a gaseous form up to the containment due to some processes that limit the formation of caesium iodide in the reactor coolant system (RCS). The formation of caesium iodide, which is assumed to be the dominant form of iodine in the RCS, would be notably limited due to the presence of other elements reacting with caesium.
    An experimental study has been launched at VTT investigating the behaviour of iodine on primary circuit surfaces during a severe nuclear accident. Caesium iodide and molybdenum trioxide were used as a nonradioactive precursor materials in order to highlight the effects of carrier gas composition and oxygen partial pressure on the chemistry and transport. Aerosols and gaseous species released from the reaction crucible were sampled at 150°C on filters and liquid scrubbers and analysed with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). Aerosol number size distributions were measured with Scanning Mobility Particle Sizer (SMPS), with series 3080 platform, series 3081 Differential Mobility Analyzer (DMA) and series 3775 Condensation Particle Counter (CPC) as well as with Electric Low Pressure Impactor (ELPI).
    The study investigated, first, the influence of molybdenum presence on the caesium iodide behaviour under two atmospheres: Ar/H2O and Ar/Air. Experiments showed that the transport of gaseous iodine was enhanced by the presence of molybdenum, explained by the formation of a caesium molybdates in the crucible. This suggests that a reaction between condensed caesium iodide and molybdenum is possible at the surface of primary circuit in these conditions. In addition, the oxygen partial pressure prevailing in the studied conditions was determined as an influential parameter in the reaction. The effect of molybdenum on the release of gaseous iodine from CsI-MoO3 precursor mixtures with different Mo/Cs molar ratios and atmosphere compositions was investigated
    Original languageEnglish
    Number of pages8
    Publication statusPublished - 2019
    MoE publication typeNot Eligible
    Event28th International Conference Nuclear Energy for New Europe, NENE 2019 - Grand Hotel Bernardin, Portorož, Slovenia
    Duration: 9 Sep 201912 Sep 2019
    Conference number: 28
    http://www.nss.si/nene2019/

    Conference

    Conference28th International Conference Nuclear Energy for New Europe, NENE 2019
    Abbreviated titleNENE 2019
    CountrySlovenia
    CityPortorož
    Period9/09/1912/09/19
    Internet address

    Fingerprint

    Cesium
    Molybdenum
    Iodine
    Accidents
    Networks (circuits)
    Crucibles
    Aerosols
    Partial pressure
    Coolants
    Oxygen
    Inductively coupled plasma mass spectrometry
    Light water reactors
    Radiation counters
    Scrubbers
    Reactor cores
    Chemical analysis
    Condensation
    Gases
    cesium iodide
    Scanning

    Keywords

    • Caesium Iodide
    • Molybdenum

    Cite this

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    title = "A Separate Effect Study of the Influence of Molybdenum on Iodine and Caesium Transport in the Primary Circuit in Nuclear Severe Accident Conditions",
    abstract = "In case of a severe accident on a Light Water Reactor (LWR), iodine may be released into the environment, impacting significantly the source term. The understanding of the iodine release from the damaged reactor core and its transport in the different parts of the reactor up to the reactor containment, is thus a major issue. The analysis of the Ph{\'e}bus-FP tests brought the hypothesis that iodine keeps a gaseous form up to the containment due to some processes that limit the formation of caesium iodide in the reactor coolant system (RCS). The formation of caesium iodide, which is assumed to be the dominant form of iodine in the RCS, would be notably limited due to the presence of other elements reacting with caesium.An experimental study has been launched at VTT investigating the behaviour of iodine on primary circuit surfaces during a severe nuclear accident. Caesium iodide and molybdenum trioxide were used as a nonradioactive precursor materials in order to highlight the effects of carrier gas composition and oxygen partial pressure on the chemistry and transport. Aerosols and gaseous species released from the reaction crucible were sampled at 150°C on filters and liquid scrubbers and analysed with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). Aerosol number size distributions were measured with Scanning Mobility Particle Sizer (SMPS), with series 3080 platform, series 3081 Differential Mobility Analyzer (DMA) and series 3775 Condensation Particle Counter (CPC) as well as with Electric Low Pressure Impactor (ELPI).The study investigated, first, the influence of molybdenum presence on the caesium iodide behaviour under two atmospheres: Ar/H2O and Ar/Air. Experiments showed that the transport of gaseous iodine was enhanced by the presence of molybdenum, explained by the formation of a caesium molybdates in the crucible. This suggests that a reaction between condensed caesium iodide and molybdenum is possible at the surface of primary circuit in these conditions. In addition, the oxygen partial pressure prevailing in the studied conditions was determined as an influential parameter in the reaction. The effect of molybdenum on the release of gaseous iodine from CsI-MoO3 precursor mixtures with different Mo/Cs molar ratios and atmosphere compositions was investigated",
    keywords = "Caesium Iodide, Molybdenum",
    author = "Melany Gouello and Jouni Hokkinen and Teemu K{\"a}rkel{\"a}",
    note = "{"}The Proceedings containing full-length papers presented at the conference and accepted after peer review, will be published on the USB key after the conference and sent to the participants. {"}; 28th International Conference Nuclear Energy for New Europe, NENE 2019, NENE 2019 ; Conference date: 09-09-2019 Through 12-09-2019",
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    Gouello, M, Hokkinen, J & Kärkelä, T 2019, 'A Separate Effect Study of the Influence of Molybdenum on Iodine and Caesium Transport in the Primary Circuit in Nuclear Severe Accident Conditions', Paper presented at 28th International Conference Nuclear Energy for New Europe, NENE 2019, Portorož, Slovenia, 9/09/19 - 12/09/19.

    A Separate Effect Study of the Influence of Molybdenum on Iodine and Caesium Transport in the Primary Circuit in Nuclear Severe Accident Conditions. / Gouello, Melany; Hokkinen, Jouni; Kärkelä, Teemu.

    2019. Paper presented at 28th International Conference Nuclear Energy for New Europe, NENE 2019, Portorož, Slovenia.

    Research output: Contribution to conferenceConference articleScientificpeer-review

    TY - CONF

    T1 - A Separate Effect Study of the Influence of Molybdenum on Iodine and Caesium Transport in the Primary Circuit in Nuclear Severe Accident Conditions

    AU - Gouello, Melany

    AU - Hokkinen, Jouni

    AU - Kärkelä, Teemu

    N1 - "The Proceedings containing full-length papers presented at the conference and accepted after peer review, will be published on the USB key after the conference and sent to the participants. "

    PY - 2019

    Y1 - 2019

    N2 - In case of a severe accident on a Light Water Reactor (LWR), iodine may be released into the environment, impacting significantly the source term. The understanding of the iodine release from the damaged reactor core and its transport in the different parts of the reactor up to the reactor containment, is thus a major issue. The analysis of the Phébus-FP tests brought the hypothesis that iodine keeps a gaseous form up to the containment due to some processes that limit the formation of caesium iodide in the reactor coolant system (RCS). The formation of caesium iodide, which is assumed to be the dominant form of iodine in the RCS, would be notably limited due to the presence of other elements reacting with caesium.An experimental study has been launched at VTT investigating the behaviour of iodine on primary circuit surfaces during a severe nuclear accident. Caesium iodide and molybdenum trioxide were used as a nonradioactive precursor materials in order to highlight the effects of carrier gas composition and oxygen partial pressure on the chemistry and transport. Aerosols and gaseous species released from the reaction crucible were sampled at 150°C on filters and liquid scrubbers and analysed with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). Aerosol number size distributions were measured with Scanning Mobility Particle Sizer (SMPS), with series 3080 platform, series 3081 Differential Mobility Analyzer (DMA) and series 3775 Condensation Particle Counter (CPC) as well as with Electric Low Pressure Impactor (ELPI).The study investigated, first, the influence of molybdenum presence on the caesium iodide behaviour under two atmospheres: Ar/H2O and Ar/Air. Experiments showed that the transport of gaseous iodine was enhanced by the presence of molybdenum, explained by the formation of a caesium molybdates in the crucible. This suggests that a reaction between condensed caesium iodide and molybdenum is possible at the surface of primary circuit in these conditions. In addition, the oxygen partial pressure prevailing in the studied conditions was determined as an influential parameter in the reaction. The effect of molybdenum on the release of gaseous iodine from CsI-MoO3 precursor mixtures with different Mo/Cs molar ratios and atmosphere compositions was investigated

    AB - In case of a severe accident on a Light Water Reactor (LWR), iodine may be released into the environment, impacting significantly the source term. The understanding of the iodine release from the damaged reactor core and its transport in the different parts of the reactor up to the reactor containment, is thus a major issue. The analysis of the Phébus-FP tests brought the hypothesis that iodine keeps a gaseous form up to the containment due to some processes that limit the formation of caesium iodide in the reactor coolant system (RCS). The formation of caesium iodide, which is assumed to be the dominant form of iodine in the RCS, would be notably limited due to the presence of other elements reacting with caesium.An experimental study has been launched at VTT investigating the behaviour of iodine on primary circuit surfaces during a severe nuclear accident. Caesium iodide and molybdenum trioxide were used as a nonradioactive precursor materials in order to highlight the effects of carrier gas composition and oxygen partial pressure on the chemistry and transport. Aerosols and gaseous species released from the reaction crucible were sampled at 150°C on filters and liquid scrubbers and analysed with High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). Aerosol number size distributions were measured with Scanning Mobility Particle Sizer (SMPS), with series 3080 platform, series 3081 Differential Mobility Analyzer (DMA) and series 3775 Condensation Particle Counter (CPC) as well as with Electric Low Pressure Impactor (ELPI).The study investigated, first, the influence of molybdenum presence on the caesium iodide behaviour under two atmospheres: Ar/H2O and Ar/Air. Experiments showed that the transport of gaseous iodine was enhanced by the presence of molybdenum, explained by the formation of a caesium molybdates in the crucible. This suggests that a reaction between condensed caesium iodide and molybdenum is possible at the surface of primary circuit in these conditions. In addition, the oxygen partial pressure prevailing in the studied conditions was determined as an influential parameter in the reaction. The effect of molybdenum on the release of gaseous iodine from CsI-MoO3 precursor mixtures with different Mo/Cs molar ratios and atmosphere compositions was investigated

    KW - Caesium Iodide

    KW - Molybdenum

    UR - http://www.nss.si/nene2019/wp-content/uploads/NENE2019-BOA-2019-09-29-web.pdf

    M3 - Conference article

    ER -

    Gouello M, Hokkinen J, Kärkelä T. A Separate Effect Study of the Influence of Molybdenum on Iodine and Caesium Transport in the Primary Circuit in Nuclear Severe Accident Conditions. 2019. Paper presented at 28th International Conference Nuclear Energy for New Europe, NENE 2019, Portorož, Slovenia.