05000244/LER-2021-001, Service Water Pump a Declared Inoperable Due to Winding Failure Following Replacement Resulting in Violation of Technical Specifications LCO 3.7.8.A (One Service Water Pump Inoperable Greater
| ML21323A150 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 11/19/2021 |
| From: | Swift P Exelon Generation Co LLC |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 2021-001-00 | |
| Download: ML21323A150 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| 2442021001R00 - NRC Website | |
text
Exelon Generation November 18, 2021 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 RE. Ginna Nuclear Power Plant Renewed Facility Operating License No. DPR-18 NRC Docket No. 50-244 Paul M. Swift Site Vice President R.E. Ginna Nuclear Power Plant 1503 Lake Rd.
Ontario. NY 14519 315-791-5200 Office www.exeloncorp.com
Subject:
LER 2021-001, Service Water Pump "A" declared inoperable due to winding failure following replacement resulting in violation of Technical Specifications LCO 3.7.8.A (one Service Water pump inoperable greater than 14 days)
The attached Licensee Event Report (LER) 2021-001 is submitted under the provisions of NUREG-1022, Event Reporting Guidelines. There are no new commitments contained in this submittal. This submittal is for revision 0 of the LER.
Should you have any questions regarding this submittal, please contact Chris Bradshaw at (315) 791-3246.
Sincerely,
~OJ),(.~
Paul Swift Attachment: LER 2021-001 cc:
NRC Regional Administrator, Region 1 NRC Project Manager, Ginna NRC Resident Inspector, Ginna (e-mail)
Attachment LER 2021-001, Revision 0
Abstract
R.E. Ginna Nuclear Power Plant, Unit 1 244 4
Service Water Pump "A" declared inoperable due to winding failure following replacement resulting in violation of Technical Specifications LCO 3.7.8.A (one Service Water pump inoperable greater than 14 days) 06 02 2021 2021 001 00 11 19 2021 1
100 Chris Bradshaw, Regulatory Assurance Manager 3157913246 B
BI MO US Motors Y
On 5/17/2021, the Service Water Pump "A" motor was removed from service for planned maintenance. Following maintenance, the pump was tested, declared operable, and secured. On 06/02/2021, the pump was placed into service. At 1825, after 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> of operation, the Control Room received alarms due to failure of the motor. The circuit breaker had tripped on instantaneous overcurrent. A standby Service Water Pump was started at 1826 to restore full flow. Locally there was evidence of motor overheating. The primary plant remained stable throughout the event. The motor was replaced, and Service Water Pump "A" was restored to operable on 06/05/2021.
It was later determined that the stator had experienced a turn-to-turn short that eventually shorted the coil to ground through the stator core and to an adjacent phase causing a phase to phase short circuit and subsequent breaker trip. The most likely cause of the turn-to turn short was a defect in the magnet wire insulation used in the coils during a motor rewind in 2006. The exact type of latent defect could not be determined; therefore, reasonable assurance of operability of Service Water Pump "A" could not be established. As a result, the Service Water Pump was inoperable for a duration longer than allowed by Technical Specifications Limiting Condition for Operation 3.7.8 Condition (A) - 14 days. This condition is reportable under 10 CFR 50.73(a)
(2)(i)(B) for a condition prohibited by Technical Specifications. Page of 05000-
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
IV. ASSESSMENT OF THE SAFETY CONSEQUENCES OF THE EVENT:
At 1825, the motor failure caused a loss of one of the two running Service Water Pumps. Flow was restored by manually starting the Service Water Pump "B" at 1826 per the appropriate response procedure which restored SW header pressure to pre event pressure (70 psig). Service Water loops are normally cross-tied, and the one (1) running Service Water Pump maintained flow through both loops.
Based on the above considerations and the rapid response by Operations to start and restore normal service water flow to both loops, this event is not considered to have had any significant effect on the health and safety of the public.
V. CORRECTIVE ACTIONS
The failed motor was removed and replaced to restore operability of Service Water Pump "A" on 06/05/2021.
Procurement and repair strategies will be evaluated for both site processes and vendor oversight of refurbishment. For the windings, enamel thickness and resin application methods will be optimized to increase motor lifespans. The current rewind schedule will also be evaluated, and changes made as required. Cold/Hot start strategies will be added to maintenance and operations procedures, and training enhancements will be made based on learnings from the event.
Lastly, motor heater energization will be added to the storage strategy for Service Water Pump motors and other similarly stored motors.
VI. ADDITIONAL INFORMATION
None A. FAILED COMPONENTS:
Motor for Service Water Pump A B. PREVIOUS LERs ON SIMILAR EVENTS:
A search of all Ginna LERs submitted to the NRC determined there have been no prior LERs reporting similar motor failure.
C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:
COMPONENT - Motor IEEE 803 FUNCTION NUMBER - MO IEEE 805 SYSTEM IDENTIFICATION - BI 4
4 R.E. Ginna Nuclear Power Plant, Unit 1 244 2021 001 00