Characterization measurements of fluental and graphite in FiR1 TRIGA research reactor decommissioning waste

Antti Räty (Corresponding Author), Tiina Lavonen, Anumaija Leskinen, Jari Likonen, Cristian Postolache, Viorel Fugaru, George Bubueanu, Cristian Lungu, Adrian Bucsa

    Research output: Contribution to journalArticleScientificpeer-review

    Abstract

    The objective of this article is to study the activities and special characteristics of graphite and Fluental neutron moderator material in FiR1 TRIGA Mark II type research reactor in Finland. Quantifying the nuclide vector and total activities of decommissioning waste is a legal requirement and provides input to many other aspect of decommissioning project. Because earlier calculations of decommissioning waste nuclide inventories used partially assumed input data e.g. material compositions, measurement data is needed to validate the calculated results. Graphite and Fluental are especially important in long term final disposal of the waste, because graphite contains volatile radionuclides (14C, 3H, 36Cl) that spread rapidly in final disposal conditions and the corrosion of aluminium in Fluental will result in hydrogen pressure generation, which can accelerate the diffusion of radionuclides in the bedrock. Moreover, these types of materials are not used in Finnish power reactors and their behaviour in final disposal conditions have not been studied so thoroughly earlier. This study reports composition and activity measurements from graphite, activation and leakage of tritium in Fluental and reviews main phenomena that could occur in final disposal environment. Measured activities were compared to estimates calculated with a point-depletion code modelling the reactor irradiation history. Results are used to validate the calculated estimates of total activities and the scaling matrix method that will be used to classify the packed decommissioning waste. Due to limited number of samples, numerical results still contain variations. However, developed methods are still valuable in future analyses and measured data also rules out unexpected activities.

    Original languageEnglish
    Article number110198
    Number of pages9
    JournalNuclear Engineering and Design
    Volume353
    DOIs
    Publication statusPublished - Nov 2019
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    Decommissioning (nuclear reactors)
    decommissioning
    Research reactors
    Graphite
    graphite
    disposal
    reactors
    Radioisotopes
    Isotopes
    radionuclide
    nuclides
    radioactive isotopes
    Moderators
    Tritium
    tritium
    Aluminum
    Chemical analysis
    Waste disposal
    leakage
    power reactors

    Cite this

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    title = "Characterization measurements of fluental and graphite in FiR1 TRIGA research reactor decommissioning waste",
    abstract = "The objective of this article is to study the activities and special characteristics of graphite and Fluental neutron moderator material in FiR1 TRIGA Mark II type research reactor in Finland. Quantifying the nuclide vector and total activities of decommissioning waste is a legal requirement and provides input to many other aspect of decommissioning project. Because earlier calculations of decommissioning waste nuclide inventories used partially assumed input data e.g. material compositions, measurement data is needed to validate the calculated results. Graphite and Fluental are especially important in long term final disposal of the waste, because graphite contains volatile radionuclides (14C, 3H, 36Cl) that spread rapidly in final disposal conditions and the corrosion of aluminium in Fluental will result in hydrogen pressure generation, which can accelerate the diffusion of radionuclides in the bedrock. Moreover, these types of materials are not used in Finnish power reactors and their behaviour in final disposal conditions have not been studied so thoroughly earlier. This study reports composition and activity measurements from graphite, activation and leakage of tritium in Fluental and reviews main phenomena that could occur in final disposal environment. Measured activities were compared to estimates calculated with a point-depletion code modelling the reactor irradiation history. Results are used to validate the calculated estimates of total activities and the scaling matrix method that will be used to classify the packed decommissioning waste. Due to limited number of samples, numerical results still contain variations. However, developed methods are still valuable in future analyses and measured data also rules out unexpected activities.",
    author = "Antti R{\"a}ty and Tiina Lavonen and Anumaija Leskinen and Jari Likonen and Cristian Postolache and Viorel Fugaru and George Bubueanu and Cristian Lungu and Adrian Bucsa",
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    Characterization measurements of fluental and graphite in FiR1 TRIGA research reactor decommissioning waste. / Räty, Antti (Corresponding Author); Lavonen, Tiina; Leskinen, Anumaija; Likonen, Jari; Postolache, Cristian; Fugaru, Viorel; Bubueanu, George; Lungu, Cristian; Bucsa, Adrian.

    In: Nuclear Engineering and Design, Vol. 353, 110198, 11.2019.

    Research output: Contribution to journalArticleScientificpeer-review

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    AU - Räty, Antti

    AU - Lavonen, Tiina

    AU - Leskinen, Anumaija

    AU - Likonen, Jari

    AU - Postolache, Cristian

    AU - Fugaru, Viorel

    AU - Bubueanu, George

    AU - Lungu, Cristian

    AU - Bucsa, Adrian

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