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On the morning of April 22, 2004, a shift … On the morning of April 22, 2004, a shift turnover walkdown was in progress in the Unit 1 control room. At 0540 EDT, the Unit Shift Supervisor (USS) found the Control Room Normal HVAC Outside Air Damper, AHV-12153, closed. The pressure differential between control room air and the outside atmosphere was checked and found to be zero. This condition stops flow past the control room air intake radioactive gas monitors, rendering them inoperable. After verifying that there was no valid reason for maintaining AHV-12153 closed, it was re-opened, restoring the control room differential pressure. It was determined that AHV-12153 was closed the previous day, during switchgear maintenance. Because the Technical Specifications (TS) require the control room emergency filtration system (CREFS) to be placed in the emergency operating mode if the control room air intake radioactive gas monitors are inoperable for more than one hour, and this was not done, the units operated in a condition prohibited by the TS.</br></br>An investigation found that maintenance was performed on de-energized switchgear, exercising a cell switch which closed the outside air damper. Therefore, the cause of this event was a failure of the work planning process to recognize the impact of the planned maintenance. Changes to this process are in progress.. Changes to this process are in progress. +
April 22, 2004 +
On the morning of April 22, 2004, a shift … On the morning of April 22, 2004, a shift turnover walkdown was in progress in the Unit 1 control room. At 0540 EDT, the Unit Shift Supervisor (USS) found the Control Room Normal HVAC Outside Air Damper, AHV-12153, closed. The pressure differential between control room air and the outside atmosphere was checked and found to be zero. This condition stops flow past the control room air intake radioactive gas monitors, rendering them inoperable. After verifying that there was no valid reason for maintaining AHV-12153 closed, it was re-opened, restoring the control room differential pressure. It was determined that AHV-12153 was closed the previous day, during switchgear maintenance. Because the Technical Specifications (TS) require the control room emergency filtration system (CREFS) to be placed in the emergency operating mode if the control room air intake radioactive gas monitors are inoperable for more than one hour, and this was not done, the units operated in a condition prohibited by the TS.</br></br>An investigation found that maintenance was performed on de-energized switchgear, exercising a cell switch which closed the outside air damper. Therefore, the cause of this event was a failure of the work planning process to recognize the impact of the planned maintenance. Changes to this process are in progress.. Changes to this process are in progress. +
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2 +
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>.
04:41:59, 1 December 2017 +
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June 17, 2004 +
April 22, 2004 +
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