ENS 54760
ENS Event | |
|---|---|
05:00 Jun 1, 2020 | |
| Title | |
| Event Description | EN Revision Imported Date : 7/22/2020
PART 21 - FAILURE OF SIZE 1 AND 2 FREEDOM SERIES AUXILIARY CONTACTS The following is a summary of information received from Paragon Energy Solutions: DUKE Harris Nuclear Plant (HNP) has identified instances where Size 1 and 2 Eaton Freedom Series starters have failed to function as expected in assemblies that were originally supplied by NLI. The auxiliary contacts have degraded prematurely and have failed to change state when the starter was energized which has affected indication and other controlling actions within the circuit. The premature degradation of the auxiliary contacts with the old model NLI special coil, part number: 057018-COIL-1/2, has occurred on size 1 and 2 contactors that were continuously energized with significant run time after approximately 3 to 5 years of service time. HNP has provided information to manage the known degradation. The auxiliary contacts should be replaced at an increased frequency until new auxiliary contacts are installed along with the new design NLI special coil, part number: 057018-COIL-1/2-M. The nature of the defect is the pre-mature aging of the component within the auxiliary contact mechanism that is adjacent to the operating coil. The starter coil is potentially being subjected to voltages of a nature that elevates the temperature within the starter adjacent to the auxiliary contacts. It is recommended that the starters and coils be replaced in the applications where the units are being operated in a continuous duty application. It is also recommended that the control transformer be replaced with a true 4:1 ratio transformer. Paragon/NLI has developed a true 4:1 ratio transformer that will provide additional mitigation of this potential over-voltage condition. Replacing the transformer with a true 4:1 ratio reduces the control voltage that is being applied to the control circuit in a manner that will not prevent the unit from providing a sufficient voltage during a degraded voltage condition, and also will not subject the components to a voltage above the ratings when the supply voltage is operated above the nominal 480 VAC bus voltage. Paragon has no other recommendations as the accelerated aging of the components and the expected life based on the additional heat the units have been subjected to is unknown. Affected plants: Sharon Harris Oconee Turkey Point Columbia North Anna Waterford River Bend Beaver Valley Should you have any questions regarding this matter, please contact: Tracy Bolt Chief Nuclear Officer Paragon Energy Solutions 817-284-0077 tbolt@paragones.com
The following is the summary of an email received from Paragon Energy Solutions: The root cause of the degraded component is due to the increased voltage and the overall temperature of the starter coil at the elevated voltage. This elevated voltage and temperature has degraded the mechanism of the auxiliary contact operator to a point to which it has become separated from the parent component. Paragon/NLI has developed a new version of the special coil (part number: 057018-COIL-1/2-M) that operates at a lower temperature than the original special coil that is currently in use at HNP. When the new version of the special coil is subjected to the same voltages, the temperature is lower. The affected plants have been revised to: Sharon Harris Oconee Turkey Point Columbia North Anna Notified R1DO (Carfang), R2DO (Miller), R4DO (Drake), and Part 21 Reactors Group (email). |
| Where | |
|---|---|
| Paragon Energy Solutions Fort Worth, Texas (NRC Region 4) | |
| Organization: | Paragon Energy Solutions |
| Reporting | |
| 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
| Time - Person (Reporting Time:+708.68 h29.528 days <br />4.218 weeks <br />0.971 months <br />) | |
| Opened: | Tracy Bolt 17:41 Jun 30, 2020 |
| NRC Officer: | Brian Lin |
| Last Updated: | Jul 21, 2020 |
| 54760 - NRC Website | |
Paragon Energy Solutions with 10 CFR 21.21(d)(3)(i), Failure to Comply or Defect | |
WEEKMONTHYEARENS 571432024-05-09T04:00:0009 May 2024 04:00:00
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