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

NameVTT Technology
PublisherVTT
Number107
ISSN (Print)2242-1211
ISSN (Electronic)2242-122X

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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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).