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This 60-day report, as allowed by 10 CFR 5 … This 60-day report, as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10CFR50.73(a)(2)(iv)(A) to describe an unplanned, invalid actuation of specified systems, specifically the Unit 2 Primary Containment Isolation System (PCIS). On 3/13/12, at approximately 1604 hours, Unit 2 experienced an invalid PCIS partial isolation. An equipment operator was in the process of making an adjustment to the Reactor Protection System (RPS) MG Set output voltage during daily rounds. As the rheostat was beginning to be rotated to increase the voltage, output voltage quickly dropped below the MG Set undervoltage trip setpoint. The BC757B and BC757D MG Set output breakers opened, resulting in the loss of the 2B RPS bus causing a half scram. The half scram signal resulted in closure of the instrument nitrogen primary containment isolation valve, secondary containment normal ventilation isolation valves and start of the 'B' Standby Gas Treatment supply fan.</br>The invalid PCIS isolation was a result of the failure of the voltage adjustment rheostat for the MG Set output voltage.</br>This issue has been entered into the site Corrective Action Program (AR 1340452) for evaluation and implementation of further corrective actions. The NRC Resident Inspector has been informed of this notification.or has been informed of this notification. +
20:04:00, 13 March 2012 +
47,907 +
12:33:00, 8 May 2012 +
20:04:00, 13 March 2012 +
This 60-day report, as allowed by 10 CFR 5 … This 60-day report, as allowed by 10 CFR 50.73(a)(1), is being made under the reporting requirement in 10CFR50.73(a)(2)(iv)(A) to describe an unplanned, invalid actuation of specified systems, specifically the Unit 2 Primary Containment Isolation System (PCIS). On 3/13/12, at approximately 1604 hours, Unit 2 experienced an invalid PCIS partial isolation. An equipment operator was in the process of making an adjustment to the Reactor Protection System (RPS) MG Set output voltage during daily rounds. As the rheostat was beginning to be rotated to increase the voltage, output voltage quickly dropped below the MG Set undervoltage trip setpoint. The BC757B and BC757D MG Set output breakers opened, resulting in the loss of the 2B RPS bus causing a half scram. The half scram signal resulted in closure of the instrument nitrogen primary containment isolation valve, secondary containment normal ventilation isolation valves and start of the 'B' Standby Gas Treatment supply fan.</br>The invalid PCIS isolation was a result of the failure of the voltage adjustment rheostat for the MG Set output voltage.</br>This issue has been entered into the site Corrective Action Program (AR 1340452) for evaluation and implementation of further corrective actions. The NRC Resident Inspector has been informed of this notification.or has been informed of this notification. +
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100 +
00:00:00, 8 May 2012 +
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22:25:21, 24 September 2017 +
12:33:00, 8 May 2012 +
true +
false +
55.687 d (1,336.48 hours, 7.955 weeks, 1.831 months) +
20:04:00, 13 March 2012 +
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