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While trouble shooting, it was discovered … While trouble shooting, it was discovered that fuses for a remote switch to start the 'B' Class 1E air conditioning unit were installed in series and therefore not installed per design. Drawings show these fuses wired in parallel, rather than in series. In the series configuration, if an electrical short occurs on the Control Room side of the circuit and blew the fuse, the 'isolated' portion of the circuit, fed from the next fuse, would also loose power. Therefore, the circuit could not be re-energized and the unit could not be started in the event of a Control Room Fire.</br>The Class 1E electrical equipment air conditioning units are included in the post fire safe shutdown design to ensure adequate room cooling for the operating train of safety related electrical equipment. The air conditioning units provide a support function for Class 1E electrical equipment required for safe shutdown. The loss of the Class 1E air conditioning units does not directly result in loss of capability to achieve and maintain safe shutdown in the event of a fire. Rather, room heating beyond design limits could reduce the life of electrical components within the switchgear. </br>Qualification data exists to show that some components within the switchgear will survive the expected room temperatures and be functional following a loss of room cooling. Data does not exist for each and every component within the switchgear, so a conclusive argument cannot be made regarding equipment functionality following a loss of room cooling. Therefore, this condition resulted in an unanalyzed condition that could potentially affect post-fire safe shutdown equipment availability.</br>There are no compensatory measures required since the unit is not operating. The configuration will be corrected prior to changing to mode 4.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
18:18:00, 26 April 2008 +
44,172 +
15:41:00, 26 April 2008 +
18:18:00, 26 April 2008 +
While trouble shooting, it was discovered … While trouble shooting, it was discovered that fuses for a remote switch to start the 'B' Class 1E air conditioning unit were installed in series and therefore not installed per design. Drawings show these fuses wired in parallel, rather than in series. In the series configuration, if an electrical short occurs on the Control Room side of the circuit and blew the fuse, the 'isolated' portion of the circuit, fed from the next fuse, would also loose power. Therefore, the circuit could not be re-energized and the unit could not be started in the event of a Control Room Fire.</br>The Class 1E electrical equipment air conditioning units are included in the post fire safe shutdown design to ensure adequate room cooling for the operating train of safety related electrical equipment. The air conditioning units provide a support function for Class 1E electrical equipment required for safe shutdown. The loss of the Class 1E air conditioning units does not directly result in loss of capability to achieve and maintain safe shutdown in the event of a fire. Rather, room heating beyond design limits could reduce the life of electrical components within the switchgear. </br>Qualification data exists to show that some components within the switchgear will survive the expected room temperatures and be functional following a loss of room cooling. Data does not exist for each and every component within the switchgear, so a conclusive argument cannot be made regarding equipment functionality following a loss of room cooling. Therefore, this condition resulted in an unanalyzed condition that could potentially affect post-fire safe shutdown equipment availability.</br>There are no compensatory measures required since the unit is not operating. The configuration will be corrected prior to changing to mode 4.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector. +
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00:00:00, 26 April 2008 +
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Unanalyzed Condition Discovered Due to Improperly Installed Fuse Wiring in Class 1E Air Conditioning Unit +
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