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The licensee was performing maintenance on … The licensee was performing maintenance on "D" Steam Generator Low Level bistables when 4 (four) out of 8 (eight) trip control breakers opened possibly due to a 24 V DC power supply transient to 2 (two) of 4 (four) logic matrix relays. The reactor trip logic was verified to be functional and capable of processing valid reactor trip signals. The actuation was invalid as no plant transient occurred and no process variable was exceeded which would otherwise have required a reactor trip. </br>The licensee notified the State and the NRC Resident Inspector.</br>* * * RETRACTION ON 08/14/06 AT 0947 ET BY M. EWER TO MACKINNON * * *</br>Upon further review, the initial notification of this event is determined to have been conservative. A review of NUREG 1022, Rev. 2, 'Event Reporting Guidelines, 10 CFR 50.72 and 50.73,' as well as the supporting comments in the notice of final rulemaking for changes to 10 CFR Parts 50 and 72 contained in the Federal Register on October 25, 2000, indicates that these documents stress the need for reporting of system actuations. As stated in NUREG 1022, 'actuation of multichannel actuation systems is defined as actuation of enough channels to complete the minimum actuation logic. Therefore, single channel actuation logic,' Per the final rulemaking, 'the principal reason for reporting an actuation of one of these systems is that it is indicative of an unplanned plant transient that the NRC needs to evaluate to determine if action is necessary to address a safety problem.'</br>In the event described in CR-06-06880, a portion of the RPS actuation sufficiently to cause four of the eight TCBs to open (i.e, a half trip), but not enough channels actuated to complete the minimum actuation logic for RPS (i.e, insufficient channels to fulfill the safety function of the RPS to deenergized the control rod drive mechanisms to shutdown the reactor). There was no unplanned plant transient as a result of the half trip.</br>Determination</br>Based on the above assessment, this condition in NOT reportable per 10 CFR 50.73(a)(2)(iv)(A) as an actuation of any of the systems listed in paragraph 10 CFR 50.73(a)(2)(iv)(B).</br>Accordingly, the report of a 4 hour non-emergency event under 10 CFR 50.72(b)(2)(iv)(b) for a half RPS trip actuation should be withdrawn.</br>R1DO (Lorson) notified.</br>The NRC Resident Inspector will be notified by the licensee of this retraction.tified by the licensee of this retraction.
13:45:00, 25 July 2006 +
42,725 +
11:41:00, 25 July 2006 +
13:45:00, 25 July 2006 +
The licensee was performing maintenance on … The licensee was performing maintenance on "D" Steam Generator Low Level bistables when 4 (four) out of 8 (eight) trip control breakers opened possibly due to a 24 V DC power supply transient to 2 (two) of 4 (four) logic matrix relays. The reactor trip logic was verified to be functional and capable of processing valid reactor trip signals. The actuation was invalid as no plant transient occurred and no process variable was exceeded which would otherwise have required a reactor trip. </br>The licensee notified the State and the NRC Resident Inspector.</br>* * * RETRACTION ON 08/14/06 AT 0947 ET BY M. EWER TO MACKINNON * * *</br>Upon further review, the initial notification of this event is determined to have been conservative. A review of NUREG 1022, Rev. 2, 'Event Reporting Guidelines, 10 CFR 50.72 and 50.73,' as well as the supporting comments in the notice of final rulemaking for changes to 10 CFR Parts 50 and 72 contained in the Federal Register on October 25, 2000, indicates that these documents stress the need for reporting of system actuations. As stated in NUREG 1022, 'actuation of multichannel actuation systems is defined as actuation of enough channels to complete the minimum actuation logic. Therefore, single channel actuation logic,' Per the final rulemaking, 'the principal reason for reporting an actuation of one of these systems is that it is indicative of an unplanned plant transient that the NRC needs to evaluate to determine if action is necessary to address a safety problem.'</br>In the event described in CR-06-06880, a portion of the RPS actuation sufficiently to cause four of the eight TCBs to open (i.e, a half trip), but not enough channels actuated to complete the minimum actuation logic for RPS (i.e, insufficient channels to fulfill the safety function of the RPS to deenergized the control rod drive mechanisms to shutdown the reactor). There was no unplanned plant transient as a result of the half trip.</br>Determination</br>Based on the above assessment, this condition in NOT reportable per 10 CFR 50.73(a)(2)(iv)(A) as an actuation of any of the systems listed in paragraph 10 CFR 50.73(a)(2)(iv)(B).</br>Accordingly, the report of a 4 hour non-emergency event under 10 CFR 50.72(b)(2)(iv)(b) for a half RPS trip actuation should be withdrawn.</br>R1DO (Lorson) notified.</br>The NRC Resident Inspector will be notified by the licensee of this retraction.tified by the licensee of this retraction.
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100 +
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