SYMPOSIA PAPER Published: 01 January 2000

An Analysis of Baffle/Former Bolt Cracking in French PWRs


Irradiation-assisted stress corrosion cracking (IASCC) has been observed in various highly irradiated, stainless steel core components of both Boiling Water and Pressurized Water nuclear reactors. This phenomenon is believed to be responsible for cracking detected by ultrasonic nondestructive examination of some Type 316L stainless steel baffle/former bolts in six first generation CP0 series PWRs operating in France. Similar bolt failures in PWR core structures have been confirmed more recently in other countries. This paper describes a statistical analysis of the French observations. The objective was to determine whether any of the known fabrication and operating characteristics of the baffle/former bolts could be identified as having an important influence on the extent of bolt cracking. This information has been used to aid decisions concerning inspection frequency, possible replacement of cracked bolts, and selection of more resistant materials.

Author Information

Scott, PM
Framatome, Paris La Défense, France
Meunier, MC
Framatome, Paris La Défense, France
Deydier, D
SEPTEN, Electricité de France, Villeurbanne, France
Silvestre, S
SEPTEN, Electricité de France, Villeurbanne, France
Trenty, A
DPN, Electricité de France, Saint-Denis, France
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Developed by Committee: G01
Pages: 210–223
DOI: 10.1520/STP10220S
ISBN-EB: 978-0-8031-5447-6
ISBN-13: 978-0-8031-2874-3