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The following information was provided by … The following information was provided by the licensee via phone and email:</br>At 1051 CDT on 8/30/2024, during transfer of 4KV shutdown bus 1 to support Unit 1 shutdown activities, the alternate feeder breaker failed to close resulting in 4KV shutdown boards 'A' and 'B' experiencing an under voltage condition. This resulted in 'A' and 'B' diesel generators automatically starting and tying to their respective boards. This condition also caused a loss of reactor protection system (RPS) channel 'A' on Units 1 and 2, resulting in invalid actuation of primary containment isolation system Groups 2, 3, 6, and 8. The failure of the board to transfer was identified during preparation for the evolution, contingency actions were prepared and implemented as planned. The breaker failure to close has been corrected and 4KV shutdown bus 1 is energized on alternate. 4KV shutdown boards 'A' and 'B' have been restored to offsite power supplies and the diesel generators are secured. </br>All systems responded as expected for the loss of voltage. This event requires an 8-hour report per 10 CFR 50.72(b)(3)(iv)(A). There was no impact to the health and safety of the public or plant personnel. The NRC resident has been notified.</br>The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:</br>The change in reactor power from 70 percent to 40 percent was not as a result of the failed breaker, rather Browns Ferry Unit 1's change in reactor power was due to a scheduled reactor shutdown which was in progress. In regards to the Unit 2 loss of channel 'A' RPS, this was not a specified system actuation. The actuation of the 'A' and 'B' diesel generators were the specified system actuation. Although the 'A' and 'B' diesels are common to both Units 1 and 2, only Unit 1 credits these specific diesel generators for accident mitigation. As such, this event is only reportable from Unit 1. Unit 2 did not experience a specified system actuation.t experience a specified system actuation.
15:51:00, 30 August 2024 +
18:30:00, 30 August 2024 +
15:51:00, 30 August 2024 +
The following information was provided by … The following information was provided by the licensee via phone and email:</br>At 1051 CDT on 8/30/2024, during transfer of 4KV shutdown bus 1 to support Unit 1 shutdown activities, the alternate feeder breaker failed to close resulting in 4KV shutdown boards 'A' and 'B' experiencing an under voltage condition. This resulted in 'A' and 'B' diesel generators automatically starting and tying to their respective boards. This condition also caused a loss of reactor protection system (RPS) channel 'A' on Units 1 and 2, resulting in invalid actuation of primary containment isolation system Groups 2, 3, 6, and 8. The failure of the board to transfer was identified during preparation for the evolution, contingency actions were prepared and implemented as planned. The breaker failure to close has been corrected and 4KV shutdown bus 1 is energized on alternate. 4KV shutdown boards 'A' and 'B' have been restored to offsite power supplies and the diesel generators are secured. </br>All systems responded as expected for the loss of voltage. This event requires an 8-hour report per 10 CFR 50.72(b)(3)(iv)(A). There was no impact to the health and safety of the public or plant personnel. The NRC resident has been notified.</br>The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:</br>The change in reactor power from 70 percent to 40 percent was not as a result of the failed breaker, rather Browns Ferry Unit 1's change in reactor power was due to a scheduled reactor shutdown which was in progress. In regards to the Unit 2 loss of channel 'A' RPS, this was not a specified system actuation. The actuation of the 'A' and 'B' diesel generators were the specified system actuation. Although the 'A' and 'B' diesels are common to both Units 1 and 2, only Unit 1 credits these specific diesel generators for accident mitigation. As such, this event is only reportable from Unit 1. Unit 2 did not experience a specified system actuation.t experience a specified system actuation.
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00:00:00, 30 August 2024 +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
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0.11 d (2.65 hours, 0.0158 weeks, 0.00363 months) +
15:51:00, 30 August 2024 +
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