Advanced flaw production method for in-service inspection qualification mock-ups

Mika Kemppainen (Corresponding Author), Iikka Virkkunen, Jorma Pitkänen, Raimo Paussu, Hannu Hänninen

Research output: Contribution to journalArticleScientificpeer-review

15 Citations (Scopus)

Abstract

One of the key issues in in-service inspection qualification is the representativeness of the defects used in qualification specimens. The best representativeness is achieved with realistic defects. However, present specimen production techniques have some significant weaknesses, such as unrealistic defects or additional alterations induced in the surrounding material. Specimens manufactured, for example, by weld implantation or with weld solidification defects always result in one or more extra weld interfaces. These interfaces can be detected by NDT. To overcome problems with the current specimens, a new defect manufacturing technique was developed. The new technique produces natural, representative defects without introducing additional weld metal or other unwanted alterations to the specimen.

The new method enables artificial production of single, separate fatigue cracks by thermal loading. The method is based on a natural thermal fatigue damage mechanism and enables production of real cracks directly into the samples. Cracks are produced without welding or machining and without any preliminary surface treatment or artificial initiator such as a notch or a precrack. Single crack or a network of cracks can be induced into the base material, welded areas, HAZ, weld claddings, threaded areas, T-joints, etc. The location, orientation and size of produced cracks can be accurately controlled. Produced cracks can be used to simulate different types of service-induced cracks such as thermal fatigue, mechanical fatigue and stress corrosion cracks. It is shown that artificially produced thermal fatigue cracks correspond well with the real, service-induced cracks and overcome the problems of traditional qualification specimen manufacturing techniques.
Original languageEnglish
Pages (from-to)105-117
Number of pages13
JournalNuclear Engineering and Design
Volume224
Issue number1
DOIs
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed

Fingerprint

Mockups
production engineering
qualifications
inspection
crack
cracks
Inspection
Cracks
Defects
defects
defect
Welds
fatigue
Thermal fatigue
thermal fatigue
inspection service
method
manufacturing
stress corrosion
Fatigue damage

Keywords

  • nuclear power plants
  • nuclear reactor safety
  • nuclear safety
  • thermal fatigue
  • fatique
  • crack initiation
  • crack propagation
  • cracking
  • pipes
  • ultrasonic inspection
  • ultrasonic tests

Cite this

Kemppainen, Mika ; Virkkunen, Iikka ; Pitkänen, Jorma ; Paussu, Raimo ; Hänninen, Hannu. / Advanced flaw production method for in-service inspection qualification mock-ups. In: Nuclear Engineering and Design. 2003 ; Vol. 224, No. 1. pp. 105-117.
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author = "Mika Kemppainen and Iikka Virkkunen and Jorma Pitk{\"a}nen and Raimo Paussu and Hannu H{\"a}nninen",
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Kemppainen, M, Virkkunen, I, Pitkänen, J, Paussu, R & Hänninen, H 2003, 'Advanced flaw production method for in-service inspection qualification mock-ups', Nuclear Engineering and Design, vol. 224, no. 1, pp. 105-117. https://doi.org/10.1016/S0029-5493(03)00078-5

Advanced flaw production method for in-service inspection qualification mock-ups. / Kemppainen, Mika (Corresponding Author); Virkkunen, Iikka; Pitkänen, Jorma; Paussu, Raimo; Hänninen, Hannu.

In: Nuclear Engineering and Design, Vol. 224, No. 1, 2003, p. 105-117.

Research output: Contribution to journalArticleScientificpeer-review

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T1 - Advanced flaw production method for in-service inspection qualification mock-ups

AU - Kemppainen, Mika

AU - Virkkunen, Iikka

AU - Pitkänen, Jorma

AU - Paussu, Raimo

AU - Hänninen, Hannu

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AB - One of the key issues in in-service inspection qualification is the representativeness of the defects used in qualification specimens. The best representativeness is achieved with realistic defects. However, present specimen production techniques have some significant weaknesses, such as unrealistic defects or additional alterations induced in the surrounding material. Specimens manufactured, for example, by weld implantation or with weld solidification defects always result in one or more extra weld interfaces. These interfaces can be detected by NDT. To overcome problems with the current specimens, a new defect manufacturing technique was developed. The new technique produces natural, representative defects without introducing additional weld metal or other unwanted alterations to the specimen.The new method enables artificial production of single, separate fatigue cracks by thermal loading. The method is based on a natural thermal fatigue damage mechanism and enables production of real cracks directly into the samples. Cracks are produced without welding or machining and without any preliminary surface treatment or artificial initiator such as a notch or a precrack. Single crack or a network of cracks can be induced into the base material, welded areas, HAZ, weld claddings, threaded areas, T-joints, etc. The location, orientation and size of produced cracks can be accurately controlled. Produced cracks can be used to simulate different types of service-induced cracks such as thermal fatigue, mechanical fatigue and stress corrosion cracks. It is shown that artificially produced thermal fatigue cracks correspond well with the real, service-induced cracks and overcome the problems of traditional qualification specimen manufacturing techniques.

KW - nuclear power plants

KW - nuclear reactor safety

KW - nuclear safety

KW - thermal fatigue

KW - fatique

KW - crack initiation

KW - crack propagation

KW - cracking

KW - pipes

KW - ultrasonic inspection

KW - ultrasonic tests

U2 - 10.1016/S0029-5493(03)00078-5

DO - 10.1016/S0029-5493(03)00078-5

M3 - Article

VL - 224

SP - 105

EP - 117

JO - Nuclear Engineering and Design

JF - Nuclear Engineering and Design

SN - 0029-5493

IS - 1

ER -