05000269/LER-1980-040, Forwards LER 80-040/01T-0.Detailed Event Analysis Encl
| ML20005A420 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 03/10/1981 |
| From: | Parker W DUKE POWER CO. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20005A421 | List:
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| References | |
| NUDOCS 8106300306 | |
| Download: ML20005A420 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| 2691980040R00 - NRC Website | |
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' DUKE POWER' COMPANY Powsm Buttonwo 4a2 Socin Cacacu Srazzi CuAntorTE. N.C. asa4a w, w A,.
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Mr. James P. O'Reilly, Director
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Region II 3
101 Marietta Street, Suite 3100 jj q ;i,'. 9
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.j Re: Oconee Nuclear Station
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Docket No. 50-269
Dear Mr. O'Reilly:
Please find attached Reportable Occurrence Report R0-269/80
. This report is submitted pursuant to Oconee Nuclear Station Technical Specification 6.6.2.1.a(3), which concerns abnormal de.tradation of the RCS pressure boundary and describes an incident which is considered to be of no significance with respect.to its effect on the health and safety of the public.
My letter of January 8, 1981' addressed the delay in the preparation of this report.
Ve truly yours,
/
p.u _ t0. lWilliamO. Parker,Jrhl*
<. Lt L JLJ:pw Attachment Mr. Bill Lavallee cc; Director Office of Management & Program Analysis Nuclear Safety Analysis Center U. S. Nuclesr Regulatory Commission P. O. Box 10412 Washington, D. C.
20555 Palo Alto, California 94303 i
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DUKE POWER COMPANY OCONEE UNIT 1
- - Report Number: R0-269/80-40 Report Date: March 10, 1981 Occurrence Date: December 26, 1980 Facility: Oconee Unit 1 Seneca, South Carolina Identification of Occurrence:
1A OTSG Primary to Secondary Leak Conditions Prior. to Occurrence:
100: FP Description of Occurrence: At 0015 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> on December 26, 1980, the radiation l
monitor RIA-40 count rate increased apparently because of an OTSG tube leak.
l Grab samples indicated an approximate leak rate of 0.25 gpm. The reactor l
power was reduced to 90% FP.
This reduced the indicated leak to 0.13 gpm.
The unit was operated with the leak until February 8, 1981, when the unit incurred a turbine trip and an anticipatory reactor trip. A bubble test coaducted at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on February 13, 1981, quickly found tube 78-2 to have a leak. Eddy Current tests found tube 78-2 to have a through-wall indication at the upper edge of the 15th tube support plate. A tube stabiliter was installed in the upper tube sheet at 0430 on February 16, 1981, and the lower end was explosively plugged at 0945 the same day.
j Apparent Cause of Occurrence: During the 1979 refueling outage ISI, tube 78-2 indicated no discernable indication near the 15th tube support plate.
l However, small indications were found at the upper and lower tube sheets.
l The leak of a tube in the lane region in less than one fuel cycle has been experienced numerous times and is thought to be caused by high cycle fatigue.
l l
Analysis of Occurrence: Although this leak was an abnormal degradation of the RCS pressure boundary, removing the tube from service restored boundary l
integrity.
An operations procedure, " Control of Secondary Contamination,"
l was implemented af ter the leak was discovered. No contaminated liquids beyond the limits of 10 CFR 20 ' scaped to the environment from this leak.
This procedure was ef fective in limiting the escape of contaminated liquids from the secondary system. Gaseous activity released through the air ejectors were within the Technical Specification limits for gaseous activity released.
Therefore, the health and safety of the public were not affected.
Corrective Action
Upon discovering the leak, the Operations procedure, f
" Control of Secondary Side Contamination", was implemented. The Unit reactor i
power was reduced to keep the leakage rate below 0.20 gallons per minute.
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\\ After the unit was shutdown and the system opened, the entire lane region was Eddy Current tested. Tube 78-2, having indicated leaking during the leak test and having exibited a through-wall defect at the 15th tube sup-port place, was removed from service by installing a welded stabilizer rod in the top tube sheet and explosively plugging the bottom end of the tube.
Other tubes found to have indica: ions:
75-6, 30% @ 15th; 75-21, 30% @ 15th; 75-29, 25% @ 15th; 77-32, 25% 3 15th; 78-23, 25% 0 15th; and 78-25, 30% 0 15th.
Not any were over the pluggable limit of 40% chrough-wall indication.
l