ML19317D824
| ML19317D824 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/09/1977 |
| From: | Parker W DUKE POWER CO. |
| To: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML19317D825 | List: |
| References | |
| NUDOCS 7912100561 | |
| Download: ML19317D824 (2) | |
Text
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NRC DISTRIBUTION FOn PART 50 DOCKET MATERI AL
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DATE Or ooCvutNT Duke Power Company 5/9/77 y
Mr. Norman C. Mosel ey Charlotte, North Caro 11na parc RgCg,vg o William O. Parker Jr.
6/13/77
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Licensee Event Report (50 269/77-13') on 4/9/77, 54/12/77 and 4/16/77 Concerning one,,
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instrumentetion inoperadie......
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PLANT NAME:
ACI OWLEDGED.
Oconee Unit No. 1 RJL 6/14/77 (1-P)
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n Dunn POWER COMPANY Powra Dc Lorso 422 Sorin Cntucar STurrT. CII.AnLOTTL. N. C. 28242
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May 9, 1977
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Mr. Norman C. Moseley, Director U. S. Nuclear Regulatory Commission
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230 Peachtree Street, Northwest p'N Atlanta, Georgia 30303 r
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Re: Oconee Unit 1
'3' Docket No. 50-269 Pursuant to Sections 6.2 atffqih.
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Dear Mr. Moseley:
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of the Oconee Nuclear Station Technical Specifications, please find attached Reportable Occurrence Report R0-269/
77-13.
Ve truly yours,
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William O. Parker, Jr.
<a LJB:ge Attachment cc:
Director, Office of Management Information and Program Control 7 ; i 6.t 00:32
DUKI. POWER COMPANY OCONEE UNTT 1 GF Report No.: R0-269/77-13 Report Date: May 9, 1977 Occurrence Date: April 9, 1977, April 12, 1977 and April 16, 1977 l
Facility: Oconee Unit 1. Seneca, South Carolina Identification of Occurrence: One channel of borated water storage tank level instrumentation inoperable Conditions Prior to Occurrence: Unit at 100 percent full power Description of Occurrence:
From April 9, 1977 to April 16, 1977, three incidents occurred during which one of the two redundant channels of the Oconee Unit 1 borated water storage tank (BWST) level instruments indicated a fluctuating tank water level. The remaining instrument in all three cases indicated that the level of borated water required by Tecnnical Specifications was being maintained. The BWST level indicator was inoperable for a total of 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> during the 8 day period.
In each incident, work requests were promptly issued and investigation revealed that the BWST level instrument process line was obstructed. The line was cleared and the level indicator declared operable in each case.
On April 18, 1977, during the on-going investigation of the incidents, it was discovered that the BWST level instrument process line heat trace i
thermostats on both channels were not installed under the process line insulation. This caused continuous heating of the water in the process line resulting in boiling of the borated water, bubbles of steam and postulated deposit of a residue of boric acid on the walls of the process line.
It is felt that in the first incident clogging of the process line was caused by deposits.
In the second and third incidents, the entrain-ment of bubbles in the line caused the faulty indications.
I Apparent Cause of Occurrence:
l It is postulated that the first incident was caused by clogging of the i
process line due to buildup of boric acid residue in the process line.
The second and third incident were caused by the entrainment of bubbles in the line pos.oly formed when the lines were overheated. An impro-perly placed thermostat had caused the overheating of the process line.
Analysis of Occurrence:
This condition is considered to be reportable since it constituted operation in a degraded mode permitted by a Limiting Condition for j
operation. Technical Specification 3.3.5 makes provision for the removal from service for test or monitoring of any component of high
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^ o pressure injection, low pressure injection or reactor building spray for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> provided not more than one train of each system is afflicted.
This occurrence resulted in the loss of one of two redundant channels of BWST level indication for two hours on April 9, 1977, for one hour on April 12, 1977 and for two hours on April 16, 1977.
During these periods, the redundant level transmitter properly indicated the true level of the BWST. The conditions of the BWST required by Technical Specification 3.2 were maintained and the emergency core cooling systems would have performed as required in the unlikely event they were needed.
It is concluded that the health and safety of the public were not affected by this incident.
Corrective Action:
The process line was initially bled in each incident and upon discovery of the improperly installed thermostats, the thermostats were reinstalled under the process line installation on both channels.
The heat tracing on Oconee Unit 2 and 3 will be checked for similar conditions by June 1, 1977.
It is felt that this corrective action will eliminate future occurrences of this type.
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