ML19308B108
| ML19308B108 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/01/1974 |
| From: | DUKE POWER CO. |
| To: | |
| Shared Package | |
| ML19308B104 | List: |
| References | |
| NUDOCS 7912120831 | |
| Download: ML19308B108 (1) | |
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DUKE POWER COMPANY OCONEE UNIT 1 Report No.:
A0-269/74-ll Report Date: July 1, 1974 Occurrence Date:
June 20, 1974 Facility: Oconee Unit 1, Seneca, South Carolina Identification of Occurrence: Failure to provide redundant boric acid sources Conditions Prior to Occurrence: Units 1 and 2 at 100 percent full power Description of Occurrence:
Oconee Technical Specification 3.2.2 requires that at least one source per unit of concentrated boric acid, in addition to the borated water storage tank,be available and operable prior to critical operation.
On June 20 and June 21, 1974, maintenance personnel mistakenly disassembled Valve 1C5-68 resulting in the isolation of the concentrated boric acid storage tank (CBAST) for a total of 55 minutes.
This resulted in Unit 1 being i
critical with only the borated water storage tank as a source of concentrated boric acid.
Designation of Apparent Cause:
Personnel inadvertently performed maintenance on Valve CS-68, Unit 1 supply from CBAST, thus isolating Unit 1 from its backup supply of concentrated boric acid for 55 minutes. The error was discovered at 1430 on June 21, 1974 at which time the correct valve was repaired.
Analysis of Occurrence:
The result of performing a maintenance action on the wrong valve resulted in the loss of a redundant source of concentrated boric acid to ensure the ability to borate Unit 1 to a suberitical margin in the cold condition at the end of core life.
The borated water storage tank has sufficient capacity to effect the required action and was available for the entire time the reactor was critical.
This incident resulted in the loss of a standby backup source for 55 minutes, and it is concluded that the health and safety of the public was not affected.
Corrective ~ Action:
To prevent recurrence of similar incidents, procedures will require independent verification, where appropriate, to assure proper isolation and tagging has been accomplished.
This verification will involve both operations and maintenance personnel.
7 912120 h3/
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