Application of risk-informed approach to the in-service inspection programme of Unit 1 of Loviisa NPP

Veijo Nikula, Ossi Hietanen, Pentti Kauppinen

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

Abstract

The pre-service and in-service inspections (ISI) of the primary circuit components and piping of Loviisa NPP (VVER440) have been carried out since the start-up of the plant following the ISI-programme which is based on the requirements presented in the ASME Code Section XI. The latest 10 years' ISI programme was completed in 2007 and the preparation of the new ISI programme for following years was started in 2005. The basis for this new ISI programme is the new YVL-guideline issued in 2003 by the Finnish Radiation and Nuclear Safety Authority STUK. The guideline requires that utilities shall utilize risk-informed methodology when planning new ISI-programmes for safety class 1, 2, 3 and 4 as well as for non nuclear safety class classified piping systems. The approach applied in drafting the ISI-programme was in principle the same as in ASME XI Supplement R, Method B but the approach was applied for the whole plant. The consequence assessment was based on the re-sults of existing extensive probabilistic safety assessment (PSA) analysis according to the values for Conditional Core Damage Probability (CCDP) and Conditional Large Early Release Probability (CLERP). The failure assessment was performed on a qualitative basis by a group of Fortum's experts familiar with Loviisa NPP associated materials integrity and in-service activities. The selection of elements for inspection was based on the risk categorization and identified degradation mechanisms of the piping section in concern. In addition plant specific failure types and experience with their locations were taken into account. The operational history of the plant since 1977 and the experience gained through in-service inspections and maintenance work during the years passed gave valuable additional information for the selection of items to be inspected. The new approach has brought several new features compared to the existing ISI programme. New systems, system portions and small diameter instrumentation piping of the primary systems were included in the programme.
Original languageEnglish
Title of host publicationBaltica VIII
Subtitle of host publicationLife Management and Maintenance for Power Plants
Place of PublicationEspoo
PublisherVTT Technical Research Centre of Finland
Pages271-279
Volume1
ISBN (Electronic)978-951-38-7592-3
ISBN (Print)978-951-38-7591-6
Publication statusPublished - 2010
MoE publication typeB3 Non-refereed article in conference proceedings
EventBALTICA VIII - International Conference on Life Management and Maintenance for Power Plants - Helsinki-Stockholm, Finland
Duration: 18 May 201020 May 2010

Publication series

SeriesVTT Symposium
Number264
ISSN0357-9387

Conference

ConferenceBALTICA VIII - International Conference on Life Management and Maintenance for Power Plants
CountryFinland
CityHelsinki-Stockholm
Period18/05/1020/05/10

Fingerprint

Inspection
Piping systems
Radiation
Planning
Degradation
Networks (circuits)

Cite this

Nikula, V., Hietanen, O., & Kauppinen, P. (2010). Application of risk-informed approach to the in-service inspection programme of Unit 1 of Loviisa NPP. In Baltica VIII: Life Management and Maintenance for Power Plants (Vol. 1, pp. 271-279). Espoo: VTT Technical Research Centre of Finland. VTT Symposium, No. 264
Nikula, Veijo ; Hietanen, Ossi ; Kauppinen, Pentti. / Application of risk-informed approach to the in-service inspection programme of Unit 1 of Loviisa NPP. Baltica VIII: Life Management and Maintenance for Power Plants. Vol. 1 Espoo : VTT Technical Research Centre of Finland, 2010. pp. 271-279 (VTT Symposium; No. 264).
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Nikula, V, Hietanen, O & Kauppinen, P 2010, Application of risk-informed approach to the in-service inspection programme of Unit 1 of Loviisa NPP. in Baltica VIII: Life Management and Maintenance for Power Plants. vol. 1, VTT Technical Research Centre of Finland, Espoo, VTT Symposium, no. 264, pp. 271-279, BALTICA VIII - International Conference on Life Management and Maintenance for Power Plants, Helsinki-Stockholm, Finland, 18/05/10.

Application of risk-informed approach to the in-service inspection programme of Unit 1 of Loviisa NPP. / Nikula, Veijo; Hietanen, Ossi; Kauppinen, Pentti.

Baltica VIII: Life Management and Maintenance for Power Plants. Vol. 1 Espoo : VTT Technical Research Centre of Finland, 2010. p. 271-279 (VTT Symposium; No. 264).

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

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AB - The pre-service and in-service inspections (ISI) of the primary circuit components and piping of Loviisa NPP (VVER440) have been carried out since the start-up of the plant following the ISI-programme which is based on the requirements presented in the ASME Code Section XI. The latest 10 years' ISI programme was completed in 2007 and the preparation of the new ISI programme for following years was started in 2005. The basis for this new ISI programme is the new YVL-guideline issued in 2003 by the Finnish Radiation and Nuclear Safety Authority STUK. The guideline requires that utilities shall utilize risk-informed methodology when planning new ISI-programmes for safety class 1, 2, 3 and 4 as well as for non nuclear safety class classified piping systems. The approach applied in drafting the ISI-programme was in principle the same as in ASME XI Supplement R, Method B but the approach was applied for the whole plant. The consequence assessment was based on the re-sults of existing extensive probabilistic safety assessment (PSA) analysis according to the values for Conditional Core Damage Probability (CCDP) and Conditional Large Early Release Probability (CLERP). The failure assessment was performed on a qualitative basis by a group of Fortum's experts familiar with Loviisa NPP associated materials integrity and in-service activities. The selection of elements for inspection was based on the risk categorization and identified degradation mechanisms of the piping section in concern. In addition plant specific failure types and experience with their locations were taken into account. The operational history of the plant since 1977 and the experience gained through in-service inspections and maintenance work during the years passed gave valuable additional information for the selection of items to be inspected. The new approach has brought several new features compared to the existing ISI programme. New systems, system portions and small diameter instrumentation piping of the primary systems were included in the programme.

M3 - Conference article in proceedings

SN - 978-951-38-7591-6

VL - 1

T3 - VTT Symposium

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BT - Baltica VIII

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Nikula V, Hietanen O, Kauppinen P. Application of risk-informed approach to the in-service inspection programme of Unit 1 of Loviisa NPP. In Baltica VIII: Life Management and Maintenance for Power Plants. Vol. 1. Espoo: VTT Technical Research Centre of Finland. 2010. p. 271-279. (VTT Symposium; No. 264).