Performance of copper overpack for repository canisters

    Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

    Abstract

    The final disposal of the canisters containing spent nuclear fuel involves long term storage in a deep geological repository. The canisters include a 50 mm overpack (top layer) of oxygen free phosphorus doped (OFP) copper for corrosion protection. In storage the canister is subjected to some heating by the residual activity of the contents, requiring reliable prediction of safe creep life from the available rupture and strain properties of the overpack that includes electron beam (EB) or friction stir welds (FSW) for sealing. Assessments of creep strain and rupture at relevant service conditions are inevitably susceptible to any bias in the applied material models, the underlying material data and predictive tools. FSW appears to generally produce stronger welds, although significant creep weakening has been indicated in case of small scale root defects. In EB welds large grains and characteristic patterns of solidification result in some anisotropic mismatch to reduce creep strength and increase strain localisation of welds. In this paper FSW and EB cross weld test results are assessed and compared for creep response. The models have been converted to comply with the requirements for in-house Finite Element Assessment (FEA) code and used for simulating the FSW behaviour. The simulated strain response is compared with corresponding measurements in long term creep testing. The results of the simulations and material models are discussed in the view of targeted life span of the canister overpack. Observations are presented regarding the expected stress, strain and multi-axial constraint in the welded structure.
    Original languageEnglish
    Title of host publicationBaltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts
    EditorsPertti Auerkari, Juha Veivo
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Pages56
    ISBN (Electronic)978-951-38-8030-9
    ISBN (Print)978-951-38-8029-3
    Publication statusPublished - 2013
    MoE publication typeNot Eligible
    EventBALTICA IX - International Conference on Life Management and Maintenance for Power Plants - Helsinki-Stockholm, Finland
    Duration: 11 Jun 201313 Jun 2013

    Publication series

    SeriesVTT Technology
    Number107
    ISSN2242-1211

    Conference

    ConferenceBALTICA IX - International Conference on Life Management and Maintenance for Power Plants
    CountryFinland
    CityHelsinki-Stockholm
    Period11/06/1313/06/13

    Fingerprint

    Welds
    Copper
    Creep
    Friction
    Electron beams
    Geological repositories
    Creep testing
    Spent fuels
    Nuclear fuels
    Corrosion protection
    Solidification
    Phosphorus
    Heating
    Defects
    Oxygen

    Cite this

    Rantala, J., Auerkari, P., Holmström, S., Laukkanen, A., & Andersson, T. (2013). Performance of copper overpack for repository canisters. In P. Auerkari, & J. Veivo (Eds.), Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts (pp. 56). Espoo: VTT Technical Research Centre of Finland. VTT Technology, No. 107
    Rantala, Juhani ; Auerkari, Pertti ; Holmström, Stefan ; Laukkanen, Anssi ; Andersson, Tom. / Performance of copper overpack for repository canisters. Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. editor / Pertti Auerkari ; Juha Veivo. Espoo : VTT Technical Research Centre of Finland, 2013. pp. 56 (VTT Technology; No. 107).
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    abstract = "The final disposal of the canisters containing spent nuclear fuel involves long term storage in a deep geological repository. The canisters include a 50 mm overpack (top layer) of oxygen free phosphorus doped (OFP) copper for corrosion protection. In storage the canister is subjected to some heating by the residual activity of the contents, requiring reliable prediction of safe creep life from the available rupture and strain properties of the overpack that includes electron beam (EB) or friction stir welds (FSW) for sealing. Assessments of creep strain and rupture at relevant service conditions are inevitably susceptible to any bias in the applied material models, the underlying material data and predictive tools. FSW appears to generally produce stronger welds, although significant creep weakening has been indicated in case of small scale root defects. In EB welds large grains and characteristic patterns of solidification result in some anisotropic mismatch to reduce creep strength and increase strain localisation of welds. In this paper FSW and EB cross weld test results are assessed and compared for creep response. The models have been converted to comply with the requirements for in-house Finite Element Assessment (FEA) code and used for simulating the FSW behaviour. The simulated strain response is compared with corresponding measurements in long term creep testing. The results of the simulations and material models are discussed in the view of targeted life span of the canister overpack. Observations are presented regarding the expected stress, strain and multi-axial constraint in the welded structure.",
    author = "Juhani Rantala and Pertti Auerkari and Stefan Holmstr{\"o}m and Anssi Laukkanen and Tom Andersson",
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    Rantala, J, Auerkari, P, Holmström, S, Laukkanen, A & Andersson, T 2013, Performance of copper overpack for repository canisters. in P Auerkari & J Veivo (eds), Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. VTT Technical Research Centre of Finland, Espoo, VTT Technology, no. 107, pp. 56, BALTICA IX - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 11/06/13.

    Performance of copper overpack for repository canisters. / Rantala, Juhani; Auerkari, Pertti; Holmström, Stefan; Laukkanen, Anssi; Andersson, Tom.

    Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. ed. / Pertti Auerkari; Juha Veivo. Espoo : VTT Technical Research Centre of Finland, 2013. p. 56 (VTT Technology; No. 107).

    Research output: Chapter in Book/Report/Conference proceedingConference abstract in proceedingsScientific

    TY - CHAP

    T1 - Performance of copper overpack for repository canisters

    AU - Rantala, Juhani

    AU - Auerkari, Pertti

    AU - Holmström, Stefan

    AU - Laukkanen, Anssi

    AU - Andersson, Tom

    PY - 2013

    Y1 - 2013

    N2 - The final disposal of the canisters containing spent nuclear fuel involves long term storage in a deep geological repository. The canisters include a 50 mm overpack (top layer) of oxygen free phosphorus doped (OFP) copper for corrosion protection. In storage the canister is subjected to some heating by the residual activity of the contents, requiring reliable prediction of safe creep life from the available rupture and strain properties of the overpack that includes electron beam (EB) or friction stir welds (FSW) for sealing. Assessments of creep strain and rupture at relevant service conditions are inevitably susceptible to any bias in the applied material models, the underlying material data and predictive tools. FSW appears to generally produce stronger welds, although significant creep weakening has been indicated in case of small scale root defects. In EB welds large grains and characteristic patterns of solidification result in some anisotropic mismatch to reduce creep strength and increase strain localisation of welds. In this paper FSW and EB cross weld test results are assessed and compared for creep response. The models have been converted to comply with the requirements for in-house Finite Element Assessment (FEA) code and used for simulating the FSW behaviour. The simulated strain response is compared with corresponding measurements in long term creep testing. The results of the simulations and material models are discussed in the view of targeted life span of the canister overpack. Observations are presented regarding the expected stress, strain and multi-axial constraint in the welded structure.

    AB - The final disposal of the canisters containing spent nuclear fuel involves long term storage in a deep geological repository. The canisters include a 50 mm overpack (top layer) of oxygen free phosphorus doped (OFP) copper for corrosion protection. In storage the canister is subjected to some heating by the residual activity of the contents, requiring reliable prediction of safe creep life from the available rupture and strain properties of the overpack that includes electron beam (EB) or friction stir welds (FSW) for sealing. Assessments of creep strain and rupture at relevant service conditions are inevitably susceptible to any bias in the applied material models, the underlying material data and predictive tools. FSW appears to generally produce stronger welds, although significant creep weakening has been indicated in case of small scale root defects. In EB welds large grains and characteristic patterns of solidification result in some anisotropic mismatch to reduce creep strength and increase strain localisation of welds. In this paper FSW and EB cross weld test results are assessed and compared for creep response. The models have been converted to comply with the requirements for in-house Finite Element Assessment (FEA) code and used for simulating the FSW behaviour. The simulated strain response is compared with corresponding measurements in long term creep testing. The results of the simulations and material models are discussed in the view of targeted life span of the canister overpack. Observations are presented regarding the expected stress, strain and multi-axial constraint in the welded structure.

    M3 - Conference abstract in proceedings

    SN - 978-951-38-8029-3

    T3 - VTT Technology

    SP - 56

    BT - Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts

    A2 - Auerkari, Pertti

    A2 - Veivo, Juha

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

    ER -

    Rantala J, Auerkari P, Holmström S, Laukkanen A, Andersson T. Performance of copper overpack for repository canisters. In Auerkari P, Veivo J, editors, Baltica IX. International Conference on Life Management and Maintenance for Power Plants - Abstracts. Espoo: VTT Technical Research Centre of Finland. 2013. p. 56. (VTT Technology; No. 107).