ML20083P820
| ML20083P820 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 03/05/1984 |
| From: | Ullrich W PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 8404200188 | |
| Download: ML20083P820 (3) | |
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PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 (215)841-4000 March 5, 1984 Dr. Thomas E. Murley Of fice of Inspection & Enforcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19046
SUBJECT:
Peach Bottom Unit 2 Recirculation Piping - Moisture Monitoring System REFERENCE : J.S. Kemper, Philadelphia Electric Company, to Dr. T. E. Murley, USNRC, letter dated September 15, 1983.
Dear Dr. Murley:
This letter is submitted in accordance with Philadelphia Electric Company's commitment to report moisture detection system problems as stated in letter, J. S. Kemper, PECo, to Dr. T. E. Murley, USNRC, dated September 15, 1983.
Four such occurrences in 1983 which were previously reported as orts (LER's): 2-83-26/3L; 3-83-16/3L; 3 Licensee Event Rep /3L.
As a result of the LER rule (10 CFR 50.73) 21/3L and 3-83-24 which became effective January 1, 1984, we have re-evaluated the use of the LER system for reporting moisture monitoring system-Since these occurrences are not s,ignificant to plant problems.
it is safety nor pose a threat to public safety, we believe that inappropriate to continue to submit these occurrences as LER's.
the information contained in this type of LER will Furthermore, not provide a data base to NRC suitable for trending or pattern analysis of operational occurrences across the industry.
8404200188 840305 PDR ADOCK 05000277 S
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Dr. T. E. Murley
' March 5, 1984 Page 2 of 3 In accordance with this evaluation, Philadelphia Electric Company is submitting the following report regarding moisture monitoring system inoperability.
REFERENCE:
Docket No. 50-277 EVENT DATE:
January 25, 1984 i
REPORT DATE:
March 1, 1984 FACILITY:
Peach Bottom Atomic Power Station RD #1, Box 208,-Delta, PA 17314 This report is being submitted later than our 30 day commitment due to our evaluation of the applicability of submitting moisture monitoring system problems under. the new LER rule.
Abstract While Unit 2 was operating at power during routine surveillance j
l testing a moisture sensor in the recirculation system' moisture monitoring system was functioning improperly and the system was i
declared inoperable.
Hourly monitoring of the drywell sump pump out rates was initiated to determine drywell leakage rates.
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Cause of the event was determined to be a failed sensor circuit card assembly.
The sensor was replaced, successfully tested and returned to service.
Description of the Event:
On January 25, 1984, Peach Bottom Unit 2'was operating at 95%
power.
While conducting a routine surveillance test (ST 13.40
^
' Checkout of Moisture Monitoring System') to verify the operability of the moisture ' monitoring system, Point 7 appeared to be functioning improperly.
Point 7 is installed on weld A-AM-i 4/AHG in the
'A' recirculation loop 22 inch? manifold.
Instrument and control technicians investigated and successfuly tested Point 7, however, the sensor failed shortly thereafter and' the moisture monitoring system was declared, inoperable ~at'6:00 p.m. on January 25, 1984.
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RDr. T. E. Murley March 5, 1984 Pcga 3 of 3 Consequences of the Event:
After the system was declared inoperable, enhanced surveillance requirements (ST 13.41 ' Hourly Drywell Leak Detection') were initiated and continued until January 28, 1984 when Unit 2 was removed from service.
The purpose of ST 13.41 is to provide early. warning of reactor coolant leakage via the drywell sump collection system when the moisture monitoring system is inoperable and reactor temperature is above 212 degrees.
These surveillance requirements ensured that drywell leakage rates did not exceed the limits of Technical Specification 3.6.C.1 prior to unit shutdown.
Therefore, the safety consequences of this event are considered minimal.
Cause of the Event:
The cause of the event was a failed Techmark Limited moisture sensor circuit card.
Corrective Actions:
Hourly monitoring of the drywell sump collection system was performed until the unit was shutdown on January.28, 1984.
The inoperable sensor assembly was replaced, tested and returned to service at 4:00 p.m. on January 29, 1984.
Previous Similar Occurrences LER 2-83-26/3L, 3-83-16/3L, 3-83-21/3L, 3-83-24/3L.
Very truly yours, N'$d/f W. T. Ullrich Superintendent Nuclear. Generation Division RCB:lm Attachment cc:
A.
R. Blough, Site Inspector-J. F. Stolz, Operating Reactors Branch No. 4
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