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
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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.",
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author = "Ulla Ehrnst{\'e}n and Petri Kyt{\"o}m{\"a}ki and Ossi Hietanen",
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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

TY - GEN

T1 - Investigations on core basket bolts from a VVER 440 power plant

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

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DO - 10.1002/9781118456835.ch227

M3 - Conference article in proceedings

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.

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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