05000333/LER-2023-004, For James A. Ftizpatrick Nuclear Power Plant, Misaligned Spacer Prevented Tie Breaker Closing Coil Armature Operation on a Magne-Blast for EDG a Subsystem
| ML23335A068 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 12/01/2023 |
| From: | Sterio A Constellation Energy Company |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| JAFP-23-0066 LER 2023-004-00 | |
| Download: ML23335A068 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor |
| 3332023004R00 - NRC Website | |
text
Constellation.
JAFP-23-0066 December 1, 2023 United States Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555-0001 James A. FitzPatrick NPP P.O. Box 110 Lycoming, NY 13093 Alexander Sterio Site Vice President-JAF James A. FitzPatrick Nuclear Power Plant Renewed Facility Operating License No. DPR-059 NRC Docket No. 50-333
Subject:
Dear Sir or Madam:
LER: 2023-004, Misaligned Spacer Prevented Tie Breaker Closing Coil Armature Operation on a Magne-Blast for EOG A Subsystem This report is being submitted pursuant to 1 O CFR 50.73(a)(2)(i)(B) and 10 CFR
- 50. 73(a)(2)(v)(A).
There are no new regulatory commitments contained in this report.
Questions concerning this report may be addressed to Mr. Mark Hawes, Regulatory Assurance, at (315) 349-6659.
Sincerely,
~ ~~ Jt:::-
Alexander Sterio Site Vice President ADS/MH
Enclosure:
LER: 2023-004, Misaligned Spacer Prevented Tie Breaker Closing Coil Armature Operation on a Magne-Blast for EOG A Subsystem cc:
USNRC, Region I Administrator USNRC, Project Manager USNRC, Resident Inspector INPO Records Center (IRIS)
Abstract
On April 12, 2023, with James FitzPatrick Nuclear Power Plant (JAF) was at 100% power the Emergency Diesel Generator (EDG) A and C tie breaker (71-10504) did not close during a performance of monthly full load surveillance test (ST-9BA). This was caused by binding of the closing coil armature of the breaker due to a misaligned spacer installed in June 2021. The cause of this condition is inadequate procedural guidance to ensure proper orientation/alignment of the close coil sleeve and spacers.
Tie breaker failure to close rendered the A Emergency Diesel Generator (EDG) subsystem inoperable. It was determined that this deficiency began after the last successful test/actuation on March 13, 2023. This condition was prohibited by Technical Specifications (TS), which is reportable per 10 CFR 50.73(a)(2)(i)(B) and 10 CFR 50.73(a)(2)(v)(A).
The condition was corrected when the 71-10504 Tie Breaker was replaced on April 13, 2023. A corrective action was completed to revise MP-054.01 and MP-054.03 to improve spacer installation process and ensure proper breaker actuation.
(See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
(See Page 2 for required number of digits/characters for each block)
LICENSEE EVENT REPORT (LER)
=
Background===
The Emergency Onsite Power Supply System [EIIS identifier: EK] consists of two redundant Emergency Diesel Generator (EDG) subsystems. Each EDG subsystem consists of two EDG units. The capability of the two units in the subsystem to start, force parallel, and attain rated voltage and frequency together within 10 seconds, and run the necessary engineered safeguard loads, meets the requirements for the Emergency AC Power System.
The EDG logic system utilizes a force parallel design. This allows two EDG units to parallel onto the respective Emergency AC bus together to provide a combined load. The A subsystem tie breaker (71-10504) force parallels the A and C EDG units.
Event Description
On April 12, 2023, with James FitzPatrick Nuclear Power Plant (JAF) at 100% power the EDG A and C tie breaker (71-10504) did not close during a performance of monthly full load surveillance test (ST-9BA). The B EDG subsystem was verified to be operable. Troubleshooting identified that the issue was internal to the breaker. On April 13, the 71-10504 Magne-Blast circuit breaker was replaced and at 23:00 the A EDG subsystem was restored to service. Total out of service time was approximately 43 hours4.976852e-4 days <br />0.0119 hours <br />7.109788e-5 weeks <br />1.63615e-5 months <br />.
Event Analysis
The removed Magne-Blast circuit breaker was sent to General Electric (GE) for evaluation. The GE investigation identified that intermittent binding of the close coil armature occurred, which prevented the full stroke required to close the circuit breaker. The binding was repeated multiple times during the investigation.
Visual inspection confirmed the closing coil appeared to be askew in the assembly and the spacers were not aligned correctly.
The misaligned spacer did not allow the closing coil sleeve to seat properly in the cutout of the support. This decreased the clearance required for the closing coil armature to move freely inside the full length of the assembly. The decreased clearance caused the armature to bind against the spacer and the inside of the sleeve. The armature does not experience binding in all positions of the armature. The armature was rotated and then it was identified that it only became bound in certain positions. A properly installed coil assembly will not become loose, and closing coil will be able to operate without binding.
It was determined that the misaligned spacer was installed in June 2021 when 71-10504 was replaced. All subsequent surveillance tests were successful from June 2021 until the failure on April 12, 2023. On October 19, 2023, JAF performed tests of the removed breaker closing coil armature to demonstrate how the armature rotates during each breaker actuation. It rotates at a regular fix quantity during each actuation; therefore, the specific position which caused binding was rotated to that position during the last test on March 13, 2023. Based on this evaluation, the A EDG subsystem tie breaker 71-10504 would not have closed between March 13 and April 12, a condition which would have caused the A EDG subsystem to be inoperable. U.S. NUCLEAR REGULATORY COMMISSION (10-01-2023)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2024
- 1. FACILITY NAME 050
- 2. DOCKET NUMBER
- 3. LER NUMBER James A. FitzPatrick Nuclear Power Plant 05000333 YEAR SEQUENTIAL NUMBER REV NO.
052 2023
- - 004
- - 00 Page 3 of 4 (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
When A EDG subsystem is inoperable, Technical Specifications (TS) 3.8.1, Condition B requires it be restored to operable status within 14 days. Condition F states that if the Completion Time of Condition B cannot be met, then the unit shall be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. This condition was prohibited by TS, which is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B).
Concurrent with this condition, as reported by LER-23-003, the 7-day fuel oil supply [DE] was not met between March 27, 2023, and April 25, 2023. In addition, ST-9BB testing of the B EDG subsystem on March 27, 2023, rendered the subsystem inoperable. TS 3.8.1 Condition E applies when two EDG subsystems are inoperable.
When A and B subsystems were inoperable at the same time, between March 27 to April 13, this circumstance is reportable in accordance with 10 CFR 50.73(a)(2)(v)(A) as a condition which could have prevented the fulfillment of the EDG system safety function.
Cause
Emergency Diesel Generator A subsystem tie breaker 71-10504 failed to close due to binding of the closing coil armature due to a misaligned spacer. The cause of this event is inadequate procedural guidance, to ensure proper orientation/alignment of the close coil sleeve and spacers.
Similar Events
No previous similar events.
FAILED COMPONENT IDENTIFICATION:
Manufacturer:
General Electric Manufacturer Model Number:
AMH-4.76-250-1D Manufacturer Code:
G080 Component Code:
BKR FitzPatrick Component ID:
71-10504
Corrective Actions
Completed Actions Replaced 71-10504 Tie Breaker.
Revised procedures MP-054.01, 4.16 KV Magne-Blast Breaker and MP-054.03, 4.16 KV Magne-Blast Breaker Overhaul, for improved guidance to ensure the proper alignment of the closing coil spacers and brass sleeve or post installation force measurement of the push button actuation to verify the closing assembly operated without binding.
Planned Actions None. U.S. NUCLEAR REGULATORY COMMISSION (10-01-2023)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET APPROVED BY OMB: NO. 3150-0104 EXPIRES: 03/31/2024
- 1. FACILITY NAME 050
- 2. DOCKET NUMBER
- 3. LER NUMBER James A. FitzPatrick Nuclear Power Plant 05000333 YEAR SEQUENTIAL NUMBER REV NO.
052 2023
- - 004
- - 00 Page 4 of 4 (See NUREG-1022, R.3 for instruction and guidance for completing this form http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
Safety Significance
Nuclear safety - There were no actual nuclear consequences. This tie breaker deficiency is limited to the A EDG subsystem and to the 30 day period between March 13 and April 13. The ability of the individual EDG units A and C to start automatically was not impacted. If the appropriate checks are not achieved, the units will not force parallel; however, the first EDG unit to reach 90% of rated voltage would close onto the emergency power bus while preventing the other unit from closing on the bus. Engineered safeguard loads are automatically connected to the emergency bus in a prescribed sequence. In the case, the load expected during a loss of offsite power (LOOP) event would not challenge a single EDG unit but the worst case Design Basis Accident load for the load sequence may result in stalling that unit.
For a low fuel oil condition as reported by LER-23-003 concurrent with this tie breaker deficiency, it was concluded that there was sufficient fuel oil onsite in all four fuel oil storage tanks and that it could be transferred as needed to run all four EDGs for the required 7 day mission time. The calculation for a 7 day fuel supply assumes full load operation amongst other high standards for performance. This requirement, in conjunction with an ability to obtain replacement supplies within 7 days, supports the availability of EDGs required to shut down the reactor and to maintain it in a safe condition for an abnormal operational transient or a postulated Design Bases Accident with loss of power. The potential effect on nuclear safety related to this report is confined to the period March 27 and April 13, only for the B subsystem and only for postulated run times greater than 6 days.
Offsite Power supply remained Operable during the affected period.
References Issue Report - IR 04669409, ST-9BA Failed Level 1 Acceptance Criteria, dated April 12, 2023 Issue Report - IR 04707644, NRC idd evaluate potential failure to report, dated October 6, 2023 Issue Report - IR 04711358, PI&R Inspection NRC identified late LER, dated October 20, 2023 Issue Report - IR 04715939, Receipt of finding, dated November 7, 2023 JAF LER - LER: 2023-003, Procedure Error in Emergency Diesel Generator Fuel Oil Supply B Subsystem, JAFP-23-0032, dated June 23, 2023