ML20151W121
| ML20151W121 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 09/08/1998 |
| From: | Von Suskil J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 50-352-98-05, 50-352-98-5, 50-353-98-05, 50-353-98-5, NUDOCS 9809150185 | |
| Download: ML20151W121 (4) | |
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1 1
James D. von Suskil Vee President e---
Umerick Generating Station PECO NUCLEAR mco m,g,com,an, A Unit of PECO Energy
$ jij" Sanatoga, PA 19464-0920 610 718 3000 / Fax 610 718 3008 Pager 1800 672 2285 #0271 Intemet address: jvonsuskil@ peco-energycom 10 CFR 2.201 September 8,1998 Docket Nos. 50-352 50-353 License Nos. NPF-39 NPF-85 U.S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555
SUBJECT:
Limerick Generating Station, Units 1 and 2 Reply to a Notice of Violation i
NRC Inspection Report 50-352/98-05 and 50-353/98-05 Attached is PECO Nuclear's reply to a Notice of Vioiation for Limerick Generating Station (LGS) Unit 1, that was contained in your letter dated August 7,1998. The Notice identified one violation, with two examples, where conditions adverse to quality were not promptly identified and corrected. The attachment to this letter provides a restatement of the violations followed by our reply.
If you have any questions or require additionalinformation, please contact us.
Very truly yours, W
Enclosure Attachments cc:
H.'J. Miller, Administrator, Region I, USNRC w/ attachments
/
A. L. Burritt, USNRC Senior Resident inspector, LGS h
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9809150185 980908F ADOCK 0 gDR
Att" chm:nt Docket Nos. 50-352 and 50-353 September 8,1998 Page 1 of 3 REPLY TO A NOTICE OF VIOLATION Restatement of the Violations During an NRC inspection conducted between June 1,1998, and June 24,1998, a violation of NRC requirements was identified. In accordance with the General Statement of Policy and Procedure for NRC Enforcement Actions, NUREG-1600, the violation is listed below:
A.
10 CFR 50, Appendix B, Criterion XVI, requires, in part, that: Measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment and nonconformances are promptly identified and corrected."
Contrary to the above, the following conditions adverse to quality were not promptly identified and corrected.
1.
Defective equipment (an incorrectly wired current transformer) in the supply circuit breaker of load center 124B was not identified and corrected, and on March 22,1998 the breaker tripped unexpectedly and de-energized all the loads supplied by the load center. PECO was aware of potential wiring errors affecting the circuit breakers used at Limerick since November 1996 bas d on industry operating experience. PECO had failed to revise the periodic calibration procedure, which could have identified the incorrectly wired current transformers and prevented the event.
2.
Deficiencies (age-related failures) in Agastat relays in three panels (OA, OB, and OC-C124) were not identified and corrected. Due to higher panel temperatures, the continued use of these Agastat relays beyond their appropriate service life led to higher age-related failures, including the April 4,1998, event in which the B train of the control room emergency fresh air supply (CREFAS) system did not actuate. On June 19,1998, several such relays remained in service, considerably beyond their calculated service lives.
This is a Severity Level IV Violation (Supplement I).
i
Attachm:nt' Docket Nos. 50-352 and 50-353 4
September 8,1998 Page 2 of 3 Reciv to Violation A Admission of the Violation PECO Energy acknowledges the violation.
Reasons for the Violations Both examples cited in the_ violation were caused by untimely completion of corrective actions for self-identified problems.
The reason for example (1) of the violation, as stated in Licensee Event Report 1-98-005, Rev.
O, for Limerick Generating Station (LGS), Unit 1, is d9 scribed below.
The 124B load center tripped due to improper wiring of the current transformer (CT) circuit for one of the load center feeder breaker's protective relays. This improper i
configuration caused the feeder breaker (124B-62) to trip prematurely under normal plant loading. The improperly wired CT circuit was supplied in that configuration by the manufacturer, however, station calibration procedures were less than adequate to identify this situation. An Operating Experience item, related to CT configuration causing a premature breaker trip, was reviewed in November 1996, determined to be t
applicable, and the procedure revision action item was created. The CT configuration issue was reviewed again in 1997 when the vendor issued a 10CFR Part 21 notice for the same concern. The target breaker calibration procedure had not been revised when it was used during breaker maintenance four days prior to this event.
The reason for example (2) was work prioritization such that the review of Agastat relay service conditions and the planned relay replacements in the OA, OB, and OC-C124 panels were not completed in a timely manner. The OA, OB, and OC-C124 panels are designated as a mild environment in design documents. Relay replacement dates were therefore established, using PECON procedures, commensurate with the safety significance of the relays and the expected service environment. In 1997, failure data indicated that the service environment in the OA, OB, and OC-C124 panels may be contributing to a higher than expected failure rate. A service environment and relay failure study was initiated for the subject panels and other panels. This resulted in a recommendation that Agastat relays be established as a Maintenance Rule Program (a)(1) system. Corrective actions were initiated that included accelerated replacement of certain relays, including specific relays in the OA, OB, and OC-C124 panels.
The data analysis revealed that the higher than expected Agastat relay failure rate in these j
panels was caused by localized heating effects. The majority of relays that failed were either at the top of the panel (highest temperature in the panel) or were near energized instrument power supplies.
t Corrective Actions Taken and Results Achieved t
The corrective actions for the load center breaker issue (example (1)) are described in LER 1-98-005. An Engineering analysis was completed on March 26,1998, that determined that there was no adverse impact on the operability of load center breakers susceptible to the same
- Attrchm:nt'
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Docket Nos. 50-352 and 50-353 September 8,1998 Page 3 of 3 CT ' configuration concem. The load center breaker calibration procedure (M-C-700-230) was revised on April 4,1998. No additional load center breaker trips, due to CT configuration, have occurred since March 22,1998.
Completed corrective actions for the Agastat relay issues (example (2)) are described below.
To date,85 % of the Unit 1 and Common (oldest) Agastat relays in the subject panels (OA,08, and OC-C124) have been replaced. All of the remaining normally energized relays (including Unit 2) are scheduled for replacement prior to the end of 1998. An Engineering analysis was completed on August 4,1998, and documented the acceptability of continued use of Agastat i
relays in the OA, OB, and OC-C124 panels up to the time of their scheduled replacement.
l Engineering has evaluated the status of the Limerick Agastat relay failure analysis and replacement program, including an assessment of the technical issues raised during the June 1998 NRC inspection. Corrective actions include appropriately adjusting relay replacement due dates and frequencies, maximizing the planning and execution effort for all relays, and applying lessons leamed to the Unit 2 panels with normally energized relays. Engineering provided a presentation to station management in August,1998 on the status of the Agastat relay evaluation and replacement program.
1 Corrective Actions to Avoid Future Noncompliance As of August 28,1998, all but three (3) load center breakers had been tested with the revised test. The remaining three (3) are scheduled to be completed by December 1,1998.
Agastat relay failures and service life estimates are being tracked and evaluated on an ongoing basis and the relays are replaced on an ongoing basis. The results of the in-plant data analysis are being incorporated into the Preventive Maintenance program for each Q-listed Agastat relay. Expected service lives are being adjusted based on service environment effects, such as localized heating. The Agastat relay system Maintenance Rule Program (a)(1) action plan will be used to restore performance to (a)(2) status.
Date When Full Compliance was Achieved Full compliance was achieved on August 4,1998, when Engineering analyses were completed that supported continued operation in light of the identified load center breaker CT configuration and Agastat relay service life issues.
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