PNO-IV-98-065, on 981217,licensee Commenced Shutdown of Diablo Canyon,Unit 1 Because of 0.21 Gallons Per Minute Weld Leak.Failure Analysis Revealed,Weld Failure Resulted from Vibration Induced High Cycle Fatigue
| ML16342A614 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/21/1998 |
| From: | Pick P, David Proulx NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-IV-98-065, PNO-IV-98-65, NUDOCS 9812240018 | |
| Download: ML16342A614 (4) | |
L 'A.'INUUKX J.
REGULA '
INFORMATION DISTRIBUTIO SYSTEM (RIDS)
ACCESSION NBR:9812240018 DOC.DATE: 98/12/21 NOTARIZED: NO DOCKET FACIL:50-275 Diablo Canyon Nuclear Power Plant, Unit 1, Pacific Ga 05000275 AUTH.NAME,
~
AUTHOR AFFILIATION PICK,P.
Region 4 (Post 820201)
PROULX,D.
Region 4
(Post 820201)
RECIP. NAME RECIPIENT AFFILIATION
SUBJECT:
PNO-IV-98-065:on 981217,licensee commenced shutdown of Diablo Canyon, Unit 1 because of 0.21 gallons'er minute weld leak. Failure analysis revealed, weld failure resulted from vibration induced high cycle fatigue.
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December 21, 1998 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-IV-98-065 This pi'.Iiminery 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 Region IV staff in Arlington, Texas on this date.
Facilltar Pacific Gas & Electric Co.
Diablo Canyon 1
Avila Beach, California Dockets: 50-275 Licensee Emer enc Classification Notification of Unusual Event Alert Site Area Emergency General Emergency X Not Applicable
Subject:
'REACTOR SHUTDOWN GREATER THAN 72 HOURS On December 17, 1998, the licensee commenced shutdown of Diablo Canyon Unit 1 because of a 0.21 gallons per minute weld leak on the component cooling water side of the Reactor Coolant Pump 1-3 upper bearing lube oil cooler. At 6:11 a.m. (PST) the licensee completed the shutdown to Hot Standby. Failure analysis revealed that the weld failure resulted from vibration induced high cycle fatigue. The licensee identified that the vibration of the lube oil cooler for Reactor Coolant Pump 1-3 was significantly higher than the other three Unit 1 reactor coolant pumps. The licensee replaced the cooler with a spare.
On December 18, at 6 p.m, during routine inspections of the Reactor Coolant Pump 1-3 work area, a buildup of boric acid on the pump was identified. The licensee determined that the leakage was reactor coolant system pressure boundary leakage from the Reactor Coolant Pump 1-3 lower radial bearing resistance temperature. detector thermowell.
Following identification of this pressure boundary leakage the licensee cooled down the plant and at 7:12 p.m. on December 19, entered Cold Shutdown as required by the Technical Specifications. The licensee completed repairs of the leak on December 20.
Following the leak repair the licensee consulted with the vendor as to the effects of the boric acid on Reactor Coolant Pump 1-3. The vendor noted that, Westinghouse plants had previously experienced problems with boric acid wastage of the reactor coolant pump niotor stand base bolts. The licensee inspected these bolts on December 20, and noted that 6 of 24 bolts exhibited significant wastage. The licensee plans to examine a sample of the bolts exhibiting wastage to determine iffurther action is required.
Assuming a rapid resolution of the reactor coolant pump motor stand base bolts issue, the licensee plans to heatup on December 21, then enter Mode 2 (Startup) on December 23.
The NRC, Region IV, will review the adequacy of the licensee's resolution to the issues associated with Reactor Coolant Pump 1-3.
The state of California will be informed.
Region IV received notification of this occurrence by phone call from the Senior Resident Inspector at 12:30 a.m. on December
- 17. 1998. Region IV has informed the EDO, NRR, arid Pj 98i22400i8 98122k PDR XGE PNO-XV-98-065 PDR This intormauon nas oeen aiscussea witn tne iicensee and is current as of 2:30 p.m. on December 21, 1998.
Contact:
Gregory Pick (817)860-8270 David Proulx (805)595-2354
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