ENS Event | |
|---|---|
15:58 Jan 26, 2026 | |
| Title | Part 21 - Incorrect Tension Spring Used for 600V Breakers |
| Event Description | The following information was provided by the licensee via phone and email:
This is an initial report notification pursuant to 10 CFR Part 21.21. On January 26, 2026, Cook Nuclear Plant completed a Part 21 evaluation concerning an issue with the refurbishment kit used for K-Line series 600V Breakers supplied by ABB, Inc. An incorrect tension spring was supplied in one of the refurbishment kits. The refurbishment kits should be supplied with two tension springs: P/N 650216A00 and P/N 650216E00. The kit received was missing P/N 650216A00 and had two of P/N 650216E00. The incorrect 650216E00 spring could have been installed into a K-Line series 600V breaker in the location intended to accept the 650216A00 spring. The 650216E00 is a lighter spring and may not be capable of providing the tensioning force required to prevent an aged breaker from slow closing. A breaker's failure to charge and close properly could result in an arc fault condition. The breakers were inspected for the correct spring, which is visible from the front of the breaker between a gap in the mechanism cover and the charging handle. All breakers installed appear to have the correct springs installed. One spare breaker, not installed in the plant, appears to have had the incorrect spring installed. A written notification will be provided within 30 days. Affected Plants: Cook Nuclear Power Plant. The NRC Resident has been notified. The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance: The wrong part numbers were identified in the refurbishment kits on December 1, 2025. A site engineer noted the wrong spring installed in a spare breaker as part of the Part 21 evaluation. Corrective actions included notifying the vendor and returning the unused refurbishment kits. |
| Where | |
|---|---|
Cook  Michigan (NRC Region 3) | |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+214.2 h8.925 days <br />1.275 weeks <br />0.293 months <br />) | |
| Opened: | Amanda Schnipke 14:10 Feb 4, 2026 |
| NRC Officer: | Eric Simpson |
| Last Updated: | Feb 4, 2026 |
| 58150 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 581502026-01-26T15:58:00026 January 2026 15:58:00
[Table view]10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 - Incorrect Tension Spring Used for 600V Breakers ENS 578362025-06-06T16:00:0006 June 2025 16:00:00 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect Part 21 - Thermal Overload of Voltage Regulators 2026-01-26T15:58:00 | |