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At 1620 EDT on April 6, 2017, a Main Contr … At 1620 EDT on April 6, 2017, a Main Control Room (MCR) door was found ajar. At that time, both control room ventilation filtrations trains (CREVS) were declared inoperable in accordance with Technical Specification 3.7.10, condition B, due to the inoperability of the Control Room Envelope (CRE). At 1623 EDT, the door was closed, CREVS was declared operable and LCO 3.7.10, Condition B was exited. </br>The safety function of the CRE boundary is to ensure the in-leakage of unfiltered air into the CRE will not exceed the in-leakage assumed in the licensing basis analysis of Design Basis Accident (DBA) consequences to CRE occupants. Additionally, it ensures that the occupants are protected from hazardous chemicals and smoke.</br>This event is being reported pursuant to 10 CFR 50.72(b)(3)(v)(D).</br>NRC Resident Inspector has been notified.</br>* * * RETRACTION FROM DAVID ALLEN TO S. SANDIN ON 5/18/17 AT 1459 EDT * * *</br>Event Notification EN 52669, made on 4/06/2017, is being retracted because additional reviews have been performed supporting that a loss of safety function did not occur.</br>Watts Bar Unit 2 has concluded that there was no loss of safety function, because when the door was found open it was capable of being closed and able to support the control room envelope function. A simulation performed on 04/07/17 also showed that with the door in question opened 1-2 inches that the control room pressure would have remained above the TS required positive pressure of 0.125 inches of water.</br>The control room envelope is designed such that the door is expected to be opened to allow personnel entry and exit, and thus positive pressures in the control room will fluctuate. The event that occurred is similar to a number of individuals entering and exiting the control room in series. Since the control room envelope function was not lost, this event is not reportable and NRC Event Number 52669 is being retracted. The basis for this conclusion will be provided to the NRC Resident Inspector." </br>The licensee informed the NRC Resident Inspector. </br>Notified R2DO (Blamey).ident Inspector.
Notified R2DO (Blamey).
20:20:00, 6 April 2017 +
52,669 +
22:40:00, 6 April 2017 +
20:20:00, 6 April 2017 +
At 1620 EDT on April 6, 2017, a Main Contr … At 1620 EDT on April 6, 2017, a Main Control Room (MCR) door was found ajar. At that time, both control room ventilation filtrations trains (CREVS) were declared inoperable in accordance with Technical Specification 3.7.10, condition B, due to the inoperability of the Control Room Envelope (CRE). At 1623 EDT, the door was closed, CREVS was declared operable and LCO 3.7.10, Condition B was exited. </br>The safety function of the CRE boundary is to ensure the in-leakage of unfiltered air into the CRE will not exceed the in-leakage assumed in the licensing basis analysis of Design Basis Accident (DBA) consequences to CRE occupants. Additionally, it ensures that the occupants are protected from hazardous chemicals and smoke.</br>This event is being reported pursuant to 10 CFR 50.72(b)(3)(v)(D).</br>NRC Resident Inspector has been notified.</br>* * * RETRACTION FROM DAVID ALLEN TO S. SANDIN ON 5/18/17 AT 1459 EDT * * *</br>Event Notification EN 52669, made on 4/06/2017, is being retracted because additional reviews have been performed supporting that a loss of safety function did not occur.</br>Watts Bar Unit 2 has concluded that there was no loss of safety function, because when the door was found open it was capable of being closed and able to support the control room envelope function. A simulation performed on 04/07/17 also showed that with the door in question opened 1-2 inches that the control room pressure would have remained above the TS required positive pressure of 0.125 inches of water.</br>The control room envelope is designed such that the door is expected to be opened to allow personnel entry and exit, and thus positive pressures in the control room will fluctuate. The event that occurred is similar to a number of individuals entering and exiting the control room in series. Since the control room envelope function was not lost, this event is not reportable and NRC Event Number 52669 is being retracted. The basis for this conclusion will be provided to the NRC Resident Inspector." </br>The licensee informed the NRC Resident Inspector. </br>Notified R2DO (Blamey).ident Inspector.
Notified R2DO (Blamey).
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00:00:00, 18 May 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>.
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