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At 1000 EDT on September 9, 2017, the Divi … At 1000 EDT on September 9, 2017, the Division 2 Mechanical Draft Cooling Tower (MDCT) fans were declared inoperable due to failure of the over speed fan brake inverter. The brakes prevent fan over speed from a design basis tornado. The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS). The UHS is required to support operability of the Division 2 Emergency Equipment Cooling Water (EECW) system. The EECW system cools various safety related components, including the High Pressure Coolant Injection (HPCI) system room cooler. An unplanned HPCI inoperability occurred based on a loss of the HPCI Room Cooler. Investigation into why the Division 2 MDCT fan over speed brake inverter failed is in progress. This report is being made pursuant to 10CFR50.72(b)(3)(v)(D) as a condition that at the time of discovery could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident based on a loss of a single train safety system.</br>The licensee entered two (2) LCO Action Statements (AS); 14-day LCO AS 3.5.1 for ECCS (HPCI Inoperable) and 72-hour AS 3.7.2 for UHS. The licensee has two spare inverters on-site. After replacement and successful post-maintenance testing the licensee expects to exit both AS before 72-hours. </br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified. +
14:00:00, 9 September 2017 +
15:04:00, 9 September 2017 +
14:00:00, 9 September 2017 +
At 1000 EDT on September 9, 2017, the Divi … At 1000 EDT on September 9, 2017, the Division 2 Mechanical Draft Cooling Tower (MDCT) fans were declared inoperable due to failure of the over speed fan brake inverter. The brakes prevent fan over speed from a design basis tornado. The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS). The UHS is required to support operability of the Division 2 Emergency Equipment Cooling Water (EECW) system. The EECW system cools various safety related components, including the High Pressure Coolant Injection (HPCI) system room cooler. An unplanned HPCI inoperability occurred based on a loss of the HPCI Room Cooler. Investigation into why the Division 2 MDCT fan over speed brake inverter failed is in progress. This report is being made pursuant to 10CFR50.72(b)(3)(v)(D) as a condition that at the time of discovery could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident based on a loss of a single train safety system.</br>The licensee entered two (2) LCO Action Statements (AS); 14-day LCO AS 3.5.1 for ECCS (HPCI Inoperable) and 72-hour AS 3.7.2 for UHS. The licensee has two spare inverters on-site. After replacement and successful post-maintenance testing the licensee expects to exit both AS before 72-hours. </br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified. +
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100 +
00:00:00, 9 September 2017 +
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>.
00:32:31, 1 October 2017 +
15:04:00, 9 September 2017 +
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false +
0.0446 d (1.07 hours, 0.00637 weeks, 0.00147 months) +
14:00:00, 9 September 2017 +
URL"URL" is a <a href="/Special:Types/URL" title="Special:Types/URL">type</a> and predefined property provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a> to represent URI/URL values.