View source for PNO-IV-04-003, Southern California Edison, Unit 3 Shutdown to Repair a Letdown System Piping Leak

{{Adams
| number = ML040270293
| issue date = 01/27/2004
| title = PNO-IV-04-003: Southern California Edison, Unit 3 Shutdown to Repair a Letdown System Piping Leak
| author name = Kennedy K
| author affiliation = NRC/RGN-IV
| addressee name = 
| addressee affiliation = 
| docket = 05000362
| license number = NPF-015
| contact person = 
| document report number = PNO-IV-04-003
| document type = NRC Preliminary Notification of Event/Occurrence
| page count = 1
}}
{{#Wiki_filter:January 27, 2004 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-IV-04-003 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region IV, Arlington, Texas, staff on this date.
Facility                                              Licensee Emergency Classification Southern California Edison                                Notification of Unusual Event San Onofre, Unit 3                                        Alert Docket: 50-362                                            Site Area Emergency License: NPF-15                                           General Emergency X Not Applicable

==SUBJECT:==
UNIT 3 SHUTDOWN TO REPAIR A LETDOWN SYSTEM PIPING LEAK DESCRIPTION:
On January 24, 2004, at approximately 12:30 p.m. PST, Southern California Edison Company (SCE) began a shutdown of San Onofre Nuclear Generating Station, Unit 3, from 100 percent power. The shutdown was prompted by discovery of an approximately .09 gallon per minute leak from a weld on a section of pipe in the letdown piping inside containment. SCE identified a slight increase in reactor coolant system leakage on January 23, 2004, during the performance of a Technical Specification required reactor coolant system leakrate calculation.
SCE has determined that the leak is from a small crack in the letdown piping at the outlet of the regenerative heat exchanger, which is part of the system used to control the chemistry and volume of the reactor coolant. The crack is located in the heat affected zone adjacent to a weld. The licensees investigation and root cause analysis are ongoing. SCE identified a higher than expected vibration of the regenerative heat exchanger and piping in the vicinity of the crack and also identified a preliminary cause for the crack as high frequency vibration. SCE plans to determine and correct the cause of the crack, inspect the piping for additional cracks, and repair the existing crack. The licensee also plans to conduct similar inspections on Unit 2. Region IV inspectors will continue to monitor the licensees activities.
Region IV received notification of the intended shutdown through the NRC senior resident inspector on January 23 at 8 p.m. CST. Region IV has informed EDO, NRR, and PA. The state of California Energy Commission has been notified by e-mail.
This information has been discussed with the licensee and is current as of January 27, 2004, at 9 a.m.
PST.
This preliminary notification is issued for information only and no further action by the staff is anticipated.
ADAMS ACCESSION NUMBER: ML040270293 CONTACTS: Kriss Kennedy 817/860-8144 kmk@nrc.gov}}

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