ENS 57483
ENS Event | |
|---|---|
05:00 Oct 29, 2024 | |
| Title | Part 21 - Interim Report for Regulating Transformer |
| Event Description | The following is a synopsis of information provided by AMETEK Solidstate Controls Inc. (AMETEK) via email:
During regulating transformer system operations, the transformer may be experiencing short circuiting between coils to ground. Visual inspection for severe darkening or charring of coils, magnetic shunts, or core, and/or the use of thermal probes or infrared guns monitoring for excessive temperatures greater than 180 degrees Celsius or 355 degrees Fahrenheit may detect affected regulating transformer systems. Affected systems exhibit signs of transformer insulation system deterioration, increased audible noise from the units, blackening on any areas of the transformer, or signs of electrical shorting between windings or coil to core. The cause of the short circuiting is unknown. Component failure impact analysis and regulating transformer system electrical testing are in progress. Recommend all units currently in service with internal components, which include but are not limited to capacitors, wire harnesses, and transformer materials, with temperatures in excess of 180 degrees Celsius or 355 degrees Fahrenheit be removed from service. COMPONENT DESCRIPTION: The AMETEK SCI model numbers listed are for regulating transformers that are intended to take in AC power at 460 VAC plus or minus 10 percent and output AC power at 120 VAC plus or minus 2 percent with low harmonic distortion. Models: 85-IS0075-12 and 85-IS0150-14 AFFECTED PLANTS: Southern Nuclear Company - Vogtle Constellation Energy - Ginna
The following is a synopsis of the information provided from Ametek: Test were performed on both models (85-IS0075-14 and 85-IS0075-12). Model 85-IS0075-12 was found to be functioning as expected during testing and did not present a failure mode. Therefore, Ginna is not affected by this component. Regarding model 85-IS0075-14, dielectric testing was performed and the apparent source of the failure was a short-circuit between the secondary coil of the transformer and the magnetic shunts and center leg of the transformer core. The suspected cause of this short circuit is the design of the magnetic shunt. Various actions are being reviewed to enhance model 85-IS0150-14 specifically regarding the insulation system of the transformer around the coils and magnetic shunts. An updated report is expected to be completed in May/June. Notified R1DO (Schussler), R2DO (Pearson), Part 21 Group (email)
The following is a synopsis of the information provided from Ametek: AMETEK is submitting the final report on the potential defect. A design change is being implemented to enhance the insulation system of the transformer used in model 85-IS0150-14. This design change is expected to be released by August 31, 2025. Additionally, an alternative regulating transformer design is available that can replace the existing design. AFFECTED PLANTS: Southern Nuclear Company - Vogtle Notified R1DO (Dimitriadis), R2DO (Bacon), Part 21 Group (email) |
| Where | |
|---|---|
| Ametek Solidstate Controls Columbus, Ohio (NRC Region 3) | |
| Organization: | Ametek Solidstate Controls |
| Reporting | |
| 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
| Time - Person (Reporting Time:+1445.02 h60.209 days <br />8.601 weeks <br />1.979 months <br />) | |
| Opened: | Zachary Rumora 11:01 Dec 28, 2024 |
| NRC Officer: | Bill Nytko |
| Last Updated: | Aug 20, 2025 |
| 57483 - NRC Website | |
AMETEK with 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component | |
WEEKMONTHYEARENS 574832024-10-29T05:00:00029 October 2024 05:00:00
[Table view]10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 - Interim Report for Regulating Transformer ENS 569582023-12-13T00:00:00013 December 2023 00:00:00 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect, 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 - Interim Report for Oil Filled Capacitors ENS 551672021-04-01T04:00:0001 April 2021 04:00:00 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect, 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 Interim Report - Failure of Ametek 300V, 250A Clamp Diodes ENS 545202020-02-11T05:00:00011 February 2020 05:00:00 10 CFR 21.21(a)(2), Interim Report for Comply or Defect in Component Part 21 Report - Ametek 85-Rp2675-01 Power Supply Mounting Hardware 2024-10-29T05:00:00 | |