PNO-V-85-037A, initial Investigation Results Indicated Mode of Failure of High Point Vent Loop B Was Fatigue Cracking. Caused by Inadequate Class 2 Piping Support.Investigation Expanded to Include Walkdown,Per IE Bulletin 79-14

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PNO-V-85-037A:initial Investigation Results Indicated Mode of Failure of High Point Vent Loop B Was Fatigue Cracking. Caused by Inadequate Class 2 Piping Support.Investigation Expanded to Include Walkdown,Per IE Bulletin 79-14
ML20129B694
Person / Time
Site: Rancho Seco
Issue date: 06/28/1985
From: Eckhardt J, Myers C
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
IEB-79-14, PNO-V-85-037A, PNO-V-85-37A, NUDOCS 8507150571
Download: ML20129B694 (1)


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r PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-85-37A Date: 06/28/85 Thio preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public intsrest significance. The.information presented is as initially received without verification cr svaluation and is basically all-that is known by Region V staff on this date.

FACILITY: Sacramento Municipal Utility District Emergency Classification Rancho Seco Nuclear Power Plant Notification of Unusual Event Sacramento County, California Alert Docket No. 50-312 Site Area Emergency General Emergency Not Applicable

SUBJECT:

UNIS0LABLE REACTOR COOLANT LEAK - UPDATE Initial results of licensee investigation indicate tliat the mode of failure of the loop "B" high point vent was fatigue cracking due to inadequate class 2 piping support. The licensee

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found three instances of discrepancies between as-built class 2 piping configurations and tha design stress isometries which are considered to have contributed to the failure of the clets.l' pipe section. The licensee has expanded the scope of its investigation to include a w21kdown of all safety-related piping configurations modified since their previous walkdown in 1979 in response to Information Bulletin 79-14. This effort will utilize six, three-man ts as assisted by Bechtel stress analysis engineers.

Tha licensee expects to complete the walkdown of affected piping in the Reactor Building by 6/29 and evaluate the results prior to startup.

This information is current as of 11:00 am, (PDT) June 28, 1985.

CONTACT: J. Eckhardt C. Myers (209) 748-2791 FTS 463-3752 l

DISTRIBUTION-H St. l/ 2 MNBB Phillips G.'0'1E/W YlhWillste(l2Air Rights

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NMSS ADM:DMB Chtirman Pallidino EDO NRR IE DOT:Trans

-Comm..Zech PA OIA RES Comm. Bernthal MPA AEOD Only o A e ine Regions:$f- I? Ns A25~ 7 f?! X5 'T~ 2T

-SECY. INPO P / 2.NSAC ACRS Licensee: 11 Of CA (Reactor Licensees REGION V: FORM 211 PDR

' Resident In'specitor[) /2 (Revised 3/14/83) 71 71 850628 3 h Q {

PNO-V-85-037A PDR

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