ML20084E084
| ML20084E084 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 12/20/1974 |
| From: | White L ROCHESTER GAS & ELECTRIC CORP. |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| Shared Package | |
| ML20084E086 | List: |
| References | |
| AO-50-244-74-21, NUDOCS 8304140064 | |
| Download: ML20084E084 (3) | |
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ROCHESTER GAS AND ELECTRIC CORPORATIOtt e89 EAST AVEtlUE, POCilESTER, N.Y.14649 LFON D WHITE. Ja v at rest s.or %r
..u e e,,. s.:,,.m oo December 20, 1974
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_9 Mr. James P. O'Reilly, Director
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U. S. Atomic Energy Commission NObpk([F N.
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i 631 Park Avenue King of Prussia, Pennsylvania 19406 i
Subject:
Abnormal Occurrerice 74-21, Failure of a Boric Acid Tank k
Level Transmitter R. E. Ginna Nuclear Power Plant, Unit No.1 l
Docket No. 50-244 i
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Dear Mr. O'Rellly:
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In accordance with Technical Specifications, Article 6. 6.2a, the 4
attached report of Abnormal Cccurrence 74-21 is hereby submitted.
Very truly yours, i
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L. D. Whit,Jr.
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lj Report Number:
50-244/74-21 2a.
Report Date:
December 20, 1974 2b.
Occurrence Date:
December 11, 1974 3.
Facility:
R. E. Ginna Nuclear Power Plant, Unit No.1 4.
Identification of Occurrence:
This abnormal occurrence is defined by Technical Specification Article
- 1. 9d: Failure of one or more components of an engineered safety feature or plant protection system that causes or threatens to cause the feature or system to be incapable of performing its intended function.
5.
Conditions Prior to Cccurrence:
The unit was at full licensed power.
6.
Description of the Occurrence:
Control room annunciator " Boric Acid Tank Low Low Level 10%" annunciated.
Operations verified zero level indication on Boric Acid Tank "A" level channel LC 171.
7.
Desicnation of Apparent Cause of Occurrence:
The Beric Acid Tank "A" level channel LC 171 power supply module failed.
8.
Analysis of Cccurrence:
Two boric acid tanks together, contain a minimum of 2,000 gallons of 12 to 13% weight solution. This fluid is the initial preferred suction supply for the Safety Injection pumps upon receipt of a safety injection signal.
Each tank is equipped with two level sensing channels. The output signals of these channels operate auxiliary relays associated with the opening circuitry of the boric acid tank outlet to safety injection valves 826 A, B, C and D.
Downscale failure of a level channel in any one tank would cause the associated relay contacts for the open circuitry of these valves to be open; however, the redu'ndant level channel of that tank would still permit proper operability of all boric acid tank discharge valves.
Both level channels of the same tank would have to fail downscale to prevent these valves from permitting flow from the boric acid tanks for safety injection.
It is considered that no hazard was presented to the general public as a result of the single channel failure.
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AOR 50-244/74(~') cont'd.
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9.. t. Con ective Action:
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l In accordance with recommendations from the PORC, the failed power supply module was replaced with a spare which was bench tested prior to its installation.
10.
Failure Data:
a.
This is the firs: power supply failure in this system although similar electronic component losses have occurred randomly throughout the plant life.
b.
Equipment identification:
Manufacturer:
Foxboro Model No.:
610 AR-O Style:
A Cutput:
63-95 Volts DC, 50-10 milliamps l
1 a
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