Investigations on core basket bolts from a VVER 440 power plant

Ulla Ehrnstén, Petri Kytömäki, Ossi Hietanen

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

    3 Citations (Scopus)

    Abstract

    NDE investigations using ultrasonic inspections were performed on core basket bolts at a VVER 440 unit. Bolts with indications were replaced. Destructive investigations were performed on three bolts with indications. These investigations comprised of microstructural investigations using optical microscopy, hardness measurements and scanning electron microscopy of fracture surfaces. The bolts are M12 bolt manufactured from solution annealed Ti-stabilized stainless steel. Only one bolt had suffered from cracking. The washer of this bolt had been welded to the shielding plate, which had resulted in unintentionally high stresses. The observed cracking is regarded to be a result of intergranular stress corrosion cracking, enhanced by irradiation. The reason for the NDE indications in the other bolts were incomplete filling of the flat slot of the bolt head when the bolt was welded to the washer to prevent unscrewing of the bolt during operation.
    Original languageEnglish
    Title of host publicationProceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors
    EditorsJeremy T. Busby, Gabriel Ilevbare, Peter L. Andresen
    PublisherWiley
    Pages2067-2078
    ISBN (Electronic)978-1-1184-5683-5
    ISBN (Print)978-1-1181-3241-8
    DOIs
    Publication statusPublished - 2011
    MoE publication typeA4 Article in a conference publication
    Event15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors - Colorado Springs, CO, United States
    Duration: 7 Aug 201111 Aug 2011

    Conference

    Conference15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors
    CountryUnited States
    CityColorado Springs, CO
    Period7/08/1111/08/11

    Fingerprint

    baskets
    bolts
    power plants
    washers
    indication
    intergranular corrosion
    stress corrosion cracking
    slots
    shielding
    inspection
    stainless steels
    hardness

    Keywords

    • stainless steel
    • irradiated assisted stress corrosion cracking
    • failure analysis

    Cite this

    Ehrnstén, U., Kytömäki, P., & Hietanen, O. (2011). Investigations on core basket bolts from a VVER 440 power plant. In J. T. Busby, G. Ilevbare, & P. L. Andresen (Eds.), Proceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors (pp. 2067-2078). Wiley. https://doi.org/10.1002/9781118456835.ch227
    Ehrnstén, Ulla ; Kytömäki, Petri ; Hietanen, Ossi. / Investigations on core basket bolts from a VVER 440 power plant. Proceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors. editor / Jeremy T. Busby ; Gabriel Ilevbare ; Peter L. Andresen. Wiley, 2011. pp. 2067-2078
    @inproceedings{6650980a2f6a4bd3a5bb7d6131fb7887,
    title = "Investigations on core basket bolts from a VVER 440 power plant",
    abstract = "NDE investigations using ultrasonic inspections were performed on core basket bolts at a VVER 440 unit. Bolts with indications were replaced. Destructive investigations were performed on three bolts with indications. These investigations comprised of microstructural investigations using optical microscopy, hardness measurements and scanning electron microscopy of fracture surfaces. The bolts are M12 bolt manufactured from solution annealed Ti-stabilized stainless steel. Only one bolt had suffered from cracking. The washer of this bolt had been welded to the shielding plate, which had resulted in unintentionally high stresses. The observed cracking is regarded to be a result of intergranular stress corrosion cracking, enhanced by irradiation. The reason for the NDE indications in the other bolts were incomplete filling of the flat slot of the bolt head when the bolt was welded to the washer to prevent unscrewing of the bolt during operation.",
    keywords = "stainless steel, irradiated assisted stress corrosion cracking, failure analysis",
    author = "Ulla Ehrnst{\'e}n and Petri Kyt{\"o}m{\"a}ki and Ossi Hietanen",
    note = "Project code: 39065",
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    Ehrnstén, U, Kytömäki, P & Hietanen, O 2011, Investigations on core basket bolts from a VVER 440 power plant. in JT Busby, G Ilevbare & PL Andresen (eds), Proceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors. Wiley, pp. 2067-2078, 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors, Colorado Springs, CO, United States, 7/08/11. https://doi.org/10.1002/9781118456835.ch227

    Investigations on core basket bolts from a VVER 440 power plant. / Ehrnstén, Ulla; Kytömäki, Petri; Hietanen, Ossi.

    Proceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors. ed. / Jeremy T. Busby; Gabriel Ilevbare; Peter L. Andresen. Wiley, 2011. p. 2067-2078.

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

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    AU - Ehrnstén, Ulla

    AU - Kytömäki, Petri

    AU - Hietanen, Ossi

    N1 - Project code: 39065

    PY - 2011

    Y1 - 2011

    N2 - NDE investigations using ultrasonic inspections were performed on core basket bolts at a VVER 440 unit. Bolts with indications were replaced. Destructive investigations were performed on three bolts with indications. These investigations comprised of microstructural investigations using optical microscopy, hardness measurements and scanning electron microscopy of fracture surfaces. The bolts are M12 bolt manufactured from solution annealed Ti-stabilized stainless steel. Only one bolt had suffered from cracking. The washer of this bolt had been welded to the shielding plate, which had resulted in unintentionally high stresses. The observed cracking is regarded to be a result of intergranular stress corrosion cracking, enhanced by irradiation. The reason for the NDE indications in the other bolts were incomplete filling of the flat slot of the bolt head when the bolt was welded to the washer to prevent unscrewing of the bolt during operation.

    AB - NDE investigations using ultrasonic inspections were performed on core basket bolts at a VVER 440 unit. Bolts with indications were replaced. Destructive investigations were performed on three bolts with indications. These investigations comprised of microstructural investigations using optical microscopy, hardness measurements and scanning electron microscopy of fracture surfaces. The bolts are M12 bolt manufactured from solution annealed Ti-stabilized stainless steel. Only one bolt had suffered from cracking. The washer of this bolt had been welded to the shielding plate, which had resulted in unintentionally high stresses. The observed cracking is regarded to be a result of intergranular stress corrosion cracking, enhanced by irradiation. The reason for the NDE indications in the other bolts were incomplete filling of the flat slot of the bolt head when the bolt was welded to the washer to prevent unscrewing of the bolt during operation.

    KW - stainless steel

    KW - irradiated assisted stress corrosion cracking

    KW - failure analysis

    U2 - 10.1002/9781118456835.ch227

    DO - 10.1002/9781118456835.ch227

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    SN - 978-1-1181-3241-8

    SP - 2067

    EP - 2078

    BT - Proceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors

    A2 - Busby, Jeremy T.

    A2 - Ilevbare, Gabriel

    A2 - Andresen, Peter L.

    PB - Wiley

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    Ehrnstén U, Kytömäki P, Hietanen O. Investigations on core basket bolts from a VVER 440 power plant. In Busby JT, Ilevbare G, Andresen PL, editors, Proceedings of the 15th international Conference on Environmental Degradation of Materials in Nuclear power Systems - Water reactors. Wiley. 2011. p. 2067-2078 https://doi.org/10.1002/9781118456835.ch227