18 janvier 2018
La centrale de Callaway vient de découvrir et déclarer ce problème 39 ans après l’installation d’une vanne ! Tous les Etats-Unis sont concernés par ce problème grave qui fait que les vannes concernées pourraient rester ouvertes. Le défaut fait suite à l’augmentation de l’épaisseur du disque d’un clapet anti-retour.(*)
Les vannes defectueuses ont été fabriquées durant 7 ans à partir de 1979 jusqu’à ce que le corps de vanne soit modifié, mais les registres de suivi des vannes ne remontent qu’à 1982. Depuis cette date, 157 disques équipant les vannes ont été expédiés aux centrales atomiques américaines ainsi qu’à d’autres destinations.
(*) L’objectif de cette augmentation était d’augmenter la tenue des vannes à une pression supérieure.
Note : la liste de ventilation des 157 vannes est disponible ici : https://www.nrc.gov/docs/ML1802/ML18024A003.pdf
▸ Type : PWR - Puissance : 3 565 MWth - Première divergence : 10 / 1984 -
Available in english only
Event Number : 53177
Rep Org / Licensee : VELAN INC. -
City : Montreal State : County : Quebec, Canada
Notification Date : 01/18/2018
Notification Time : 16:06 [ET] - Event Date : 11/01/2017
Event Time : [EST] Last Update Date : 01/18/2018 Emergency Class : NON EMERGENCY 10 CFR Section : 21.21(d)(3)(i) - DEFECTS AND NONCOMPLIANCE
Event Text
PART 21 NOTIFICATION - CHECK VALVE DISC THICKNESS COULD CAUSE VALVE TO STICK OPEN
The following is a summary of the information received from Velan Inc. via facsimile :
Affected item : Velan Inc. Disc (part number 8205-012) in 4NPS Class 150 through 900 Swing Check Valve
Callaway Nuclear Plant discovered that a Velan check valve installed in 1999 was stuck open. Velan investigated and determined that in 1979, a design change increased the thickness of the disc to allow the check valve to be used in higher pressure applications than the original design. In 1985, the valve body cavity was enlarged which would preclude the disc from sticking. Therefore, the only affected valves are the valves manufactured between 1979 and 1985.
Velan’s records only go back to 1982 for purchase orders of this valve. Their records indicate 157 discs of this part number were shipped to U.S. utilities.
The following actions are being taken with respect to the disc :
▸ Cancel disc part number 8502-012
▸ Create a new disc part number to fit the body geometry of 1985 and before
▸ Create another disc part number to fit the current body geometry.
All affected utilities will be notified within a week, for information and to determine a course of action. As a minimum, Velan will recall all discs of the aforementioned part number in inventory at these utilities.
For any additional information on this matter please contact Victor Apostolescu at 514-748-7748 x 2134 or at victor.apostolescu@velan.com.
This disc has been purchased by nuclear plants in all four USNRC regions.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180119en.html
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