Release of radioactive materials from a degrading core (RADECO): RADECO summary report

Riitta Zilliacus, Tommi Kekki, Ilona Lindholm, Atso Suopajärvi

    Research output: Chapter in Book/Report/Conference proceedingChapter or book articleProfessional

    Abstract

    The formation of organic iodine on painted surface in water and in N2 was studied with and without radiation. The water pH in the experiment was 9.3 or 7. In neutral solution small amount of volatile organic iodide was detected. In high pH all volatile iodine was very small amount of inorganic iodine. Experiments performed in gas phase show some formation of volatile compounds, but most of these were rapidly adsorbed on other surfaces and only a negligible amount of organic iodine was detected. The severe accidents during shutdown conditions were examined with MELCOR code. Olkiluoto 1 was selected for the reference plant. Two accident scenarios starting during shutdown conditions with pressure vessel upper head opened were studied: a station blackout with initially intact pressure vessel (RPV) and a LOCA starting with a break in the bottom head of the RPV. The results of the calculation suggest that even a small hole in the RPV Bottom Head may allow some air ingress to the core region. If the Lower Head is intact no air ingress to the RPV would take place. Station blackout scenario resulted in high zirconium oxidation fraction, about 60%. The oxidation fraction in the Bottom Head LOCA case was 14%. In the calculated cases Ru release from the core equaled to 8-23% of the initial core inventory. The highest Ru release was obtained in the station blackout scenario.
    Original languageEnglish
    Title of host publicationSAFIR2010: The Finnish Research Programme on Nuclear Power Plant Safety 2007-2010
    Subtitle of host publicationInterim Report
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages261-275
    ISBN (Electronic)978-951-38-7267-0
    ISBN (Print)978-951-38-7266-3
    Publication statusPublished - 2009
    MoE publication typeNot Eligible

    Publication series

    SeriesVTT Tiedotteita - Research Notes
    Number2466
    ISSN1235-0605

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  • Cite this

    Zilliacus, R., Kekki, T., Lindholm, I., & Suopajärvi, A. (2009). Release of radioactive materials from a degrading core (RADECO): RADECO summary report. In SAFIR2010: The Finnish Research Programme on Nuclear Power Plant Safety 2007-2010 : Interim Report (pp. 261-275). VTT Technical Research Centre of Finland. VTT Tiedotteita - Research Notes, No. 2466 http://www.vtt.fi/inf/pdf/tiedotteet/2009/T2466.pdf