ML20084A156
| ML20084A156 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 03/30/1984 |
| From: | Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 107, NUDOCS 8404240428 | |
| Download: ML20084A156 (4) | |
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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699 PHILADELPHIA. PA.19101 (2151841-4502 VICE PNESIDENT ENGtNEtneNG AND NESE ARCH March 30, 1984 Mr. Thomas E. Murley, Director United States Nuclear Regulatory Commission Office of Inspection and nforcement, Region 1 631 Park Ave.
King of Prussia, PA 19406
SUBJECT:
Significant Deficiency Report #107 Interim Report on Defective Agastat Relays Limerick Generating Station, Units 1 and 2 NRC Construction Permits Nos. CPPR-106 & 107
REFERENCES:
(1) Telecc,n of November 29, 1983 P. K. Pavlides (PECO) to Walter Baunack (USNRC)
(2)
Significant Deficiency Report #107, Interim Report of December 28, 1983 FILE:
Qual 2-10-2 (SDR #107)
Dear Mr. Murley:
The enclosure to this letter is provided as a second interim report concerning defective Agastat GP relays at the Limerick Generating Station (LGS).
Previous information was forwarded to the USNRC via the references.
The Agastat GP relays at Limerick were tested and analyzed.
The attachment documents the results of this investigation.
We are currently evaluating a course of corrective action.
We expect to 8404240428 840330 PDR ADOCK 05000352 8
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i notify the Comission of the corrective action to be taken, within 30 days. This information will be submitted in the final report.
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i Sincerely, f-i MHH:nel-p nel-p03298411100 Attachment Copy to Director of Inspection and Enforcement i
United Gtates Nuclear Regulatory Commission Washington, D.C.
20555 i-S. K. Chaudhary, Resident NRC Inspector (Limerick)
MHilsnel-p nel-p03298411100 Copy to:
W. C. McDaniel (Bechtel)
J. M. Corcoran E. R. F.lossin (Bechtel)
R. L. itarper II. R. Walters (c/o Bechtel)
J. P. Evans V. S. Boyer G. R. Hutt/ Local File J. S. Kemper E. F. Sproat E. J. Bradley M. H.*Ilaag G. T. Brecht, Jr.
DAC (NG-8)
R. A. Mulford 3
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- Limerick Generating Station Units 1 and 2 Significant Deficiency Report #107 Defective Agastat Relays Second Interim Report March 29, 1984 1.0 Introduction This is a second interim report concerning defective Agastat GI relays at the Limerick Generating Station (LGS).
The USNRC was previously notified of this 10CFR 50.55(e) reportable condition in an interim report, dated December 28, 1983.
2.0 Description of Problem Several Agastat GP relays in the Cote Spray, Residual Heat Removal, and Reactor Protection Systems misoperated during pre-operational testing.
The normally closed contacts of these relays failed to close when the relay was de-energized.
During further testing, it was discovered that the relay contact failure is intermittent.
These defective relays were utilized in normally energized applications.
This failure has occurred in 40 relays out of several hundred tested.
The failed relays were all manufactured prior to August, 1977.
3.0 Analysis of Relay Failure A number of the defective Agastat GP relays were tested and inspected to determines (1) the exact cause of relay misoperations (2) if the relay is defective or improperly adjusted: and (3) if all of the Agastat GP relays at LGS have the potential for this problem.
Our investigation indicates that the failure is limited to normally closed contacts on relays which are normally energized. The failures occur predominantly on relays with 24VDC coils which operate at higher temperatures than the 120VAC and 125VDC coil relays.
In many cases, the failed contacts were actually closed but did not provide electrical continuity. We have determined that this condition results from two causes: 1) -inadequate spring tension on the movable contact arm, and 2) corrosion build up on the contact surfaces. Cause 1) may be the result of either improper factory adjustment or relaxation of spring tension due to heat. As this problem has become more severe u
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the longer the relays are energized, we believe the spring tension is l
relaxing as the relay ages. As for cauce 2) corrosion begins naturally on the contact surface. 'Because the failed relays were in storage for approximately seven years, we believe that the contact surface corrosion has had ample time to develop.
In addition, we believe this corrosion is accelerated in the normally energized relays because of the heat generated by the coil.
The relay design also contributes to i
this condition by failing to provide any significant wiping action for the normally closed contacts.
Our investigation to confirm these initial observations is continuing.
4.0 Safety Implicaticas The defective Agastat GP relays were discovered during pre-operational testing of the RHR, RPS and Core Spray systems at LGS.
A defective relay could adversely affect the operation of safety related equipment in these systems and other systems in which Agastat GP relays are provided.
5.0 Corrective Action We are currently evaluating a course of corrective action. A decision is expected within 30 days.
We will notify the Cormission of the corrective action to be taken in the final report. Corrective action will be completed and the final report submitted prior'to fuel lead.
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