ML19224D569
| ML19224D569 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 06/25/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| References | |
| NUDOCS 7907120627 | |
| Download: ML19224D569 (1) | |
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NUCLEAR REGULATORY COMMISSION HEG!ON V g %')
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SUITE 202, WALP UT CRE E K PL AZA June 25, 1979 Docket tio. 50-312 Sac.amento Mu.licipal Utility District P. O. Box 15830 Sacramento, California 95813 Attention: Mr. John J. Mattimoe Assistant General Manager Gentl emen:
Enclosed is IE Bulletin 79-13 which requires action by you with regard to your power reactor facility (ies) with an operating license.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this office.
Sincerely, (lC( 'S. ~c, G.-
R. H. Engelken Director
Enclosures:
1.
IE Bulletin flo. 79-13 2.
List of IE Bulletins Issued in last 12 Months cc w/encicsures:
R. J. Rodriguez, SMUD L. G. Schwieger, SMUD 7cr s.a ;
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 June 25, 1979 IE Bulletin No. 79-13 CRACKING IN FEEDWATER SYSTEM PIPING Description of Circumstances:
On May 20, 1979, Indiana and Michigan Power Company notified the NRC of cracking in two feedwater lines at their D. C. Cook Unit 2 facility. The cracking was discovered following a shutdown on May 19 to investigate leakage inside containment.
Leaking circunferential cracks were identified in the 16-inch feedwater elbows adjacent to two steam generator nozzle elbow welds.
Subsequent radiographic examination revealed crack indications in all eight stec: generator feedwater lines at this location on both Units 1 and 2.
On May 25, 1979, a letter was sent to all PWR licensees by the Office of Nuclear Reactor Regulation which infomed licensees of the D. C. Cook failures and requested specific information on feedwater system design, fabrication, inspectian and operating histories. To further explore the generic nature of the cracking problem, the Office of Inspection and Enforcerent requested licensees of PWR plants in current outages to immediately conduct volumetric examination of certain feedwater piping welds.
As a result of these actions, several other licensees with Westinghouse steam generators reported crack indications.
Southern California Edison reported on June 5,1979, that radiographic examination revealed indications of cracking in feedwater nozzle-to-piping welds on two of three steam generators of San Onofre Unit 1.
On June 15, 1979, Carc lina Power and t.ight reparted that radiography showed crack indications in sinilar locations at their H. B. Robinson Unit 2.
Duquesne Power and Light confirmec on June 18, 1979, that radiography has shown cracking in their Beaver Valley Unit 1 feedwater pipin, to vessel nozzle weld.
Public Service Electric and Gas Company reported on June 20, 1979 that Salem Unit I also has crack indications. Wisconsin Public Service company decided on June 20, 1979 to cut out a feedwater nozzle-to-pipe weld which contained questionable indication, for metallurgical examination. As of June 22, 1979 and since May 25, 1979 seven other PWR facilities have inspected the feedwater nozzle-to-pipe welds without finding cracking indications.
The feedwater nozzle-to-pipe configurations for D.C. Cook and for San Onofre are shown on the attached figures 1 and 2.
A typical feedwater pipe-to-nozzle weid joint detail showing the principal crack locations for D.C. Cook and San Onofre are shown on the attached figure 7 7 - ~ ~ ~ y.. m._ _. _ _ _ _.,,
i On March 17, 1977, during heat,t1p DUPLICATE DOCUMENT Unit 1, a leak was discovered in 7 ',
the 16-inch diameter feedwater nondestructive examination of a,into system under-9 i
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