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On Friday April 2, 2010, Unit 1 refueling … On Friday April 2, 2010, Unit 1 refueling outage activities were in progress and the 1A RPS/UPS Static Inverter was being removed from service. At 2156 hours, the inverter static transfer switch was placed in 'Bypass' which transferred the load from the inverter to the secondary alternate source. The manual bypass switch was then placed in 'Bypass' which was followed by the RPS/UPS series breakers tripping on an overvoltage condition. The actuation caused a loss of power to the IA RPS/UPS power distribution panel loads which provides power to the Division 1A and IIA RPS relays and Division IA and IIA NS4 relays. This caused primary containment isolation valves (PCIVs) to automatically close on more than one system. The IB and IIB channels were unaffected.</br>Troubleshooting determined that the secondary, alternate source voltage was 132 VAC which exceeded the overvoltage setpoint of 126 VAC. During outages, the 13kV bus voltages are higher than on-line voltages due to low operating equipment loading on the buses. The secondary alternate source to the inverter is not regulated which can result in greater than normal voltage to the RPS/UPS loads.</br>The portion of the primary containment isolation system that received an actuation signal functioned successfully. All of the affected open isolation valves automatically closed. The isolation was a partial actuation.</br>This 60-day ENS report is being made per 10CFR 50.73(a)(2)(iv)(A) and 10CFR 50.73(a)(1) to report invalid automatic actuation of systems listed in paragraph (a)(2)(iv)(B). The listed system that actuated was general containment isolation signals affecting containment isolation valves in more than one system. Primary containment isolation valves (PCIVs) closed on drywell chilled water (DWCW), reactor enclosure cooling water (RECW), primary containment instrument gas (PCIG), and suppression pool cleanup.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
01:56:00, 3 April 2010 +
45,962 +
14:53:00, 28 May 2010 +
01:56:00, 3 April 2010 +
On Friday April 2, 2010, Unit 1 refueling … On Friday April 2, 2010, Unit 1 refueling outage activities were in progress and the 1A RPS/UPS Static Inverter was being removed from service. At 2156 hours, the inverter static transfer switch was placed in 'Bypass' which transferred the load from the inverter to the secondary alternate source. The manual bypass switch was then placed in 'Bypass' which was followed by the RPS/UPS series breakers tripping on an overvoltage condition. The actuation caused a loss of power to the IA RPS/UPS power distribution panel loads which provides power to the Division 1A and IIA RPS relays and Division IA and IIA NS4 relays. This caused primary containment isolation valves (PCIVs) to automatically close on more than one system. The IB and IIB channels were unaffected.</br>Troubleshooting determined that the secondary, alternate source voltage was 132 VAC which exceeded the overvoltage setpoint of 126 VAC. During outages, the 13kV bus voltages are higher than on-line voltages due to low operating equipment loading on the buses. The secondary alternate source to the inverter is not regulated which can result in greater than normal voltage to the RPS/UPS loads.</br>The portion of the primary containment isolation system that received an actuation signal functioned successfully. All of the affected open isolation valves automatically closed. The isolation was a partial actuation.</br>This 60-day ENS report is being made per 10CFR 50.73(a)(2)(iv)(A) and 10CFR 50.73(a)(1) to report invalid automatic actuation of systems listed in paragraph (a)(2)(iv)(B). The listed system that actuated was general containment isolation signals affecting containment isolation valves in more than one system. Primary containment isolation valves (PCIVs) closed on drywell chilled water (DWCW), reactor enclosure cooling water (RECW), primary containment instrument gas (PCIG), and suppression pool cleanup.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
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00:00:00, 28 May 2010 +
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