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The Unit-2 AMSAC (Anticipated Transient Without Scram Mitigation Actuation Circuitry) actuation generated a Unit-2 turbine trip signal. The Unit-2 turbine was already tripped, but the 2A and 2B Auxiliary Feedwater and 2B Nuclear Service Water pump started. AMSAC actuation occurred during calibration of AMSAC actuation pressure switches. The licensee notified the NRC Resident Inspector.

• * * UPDATE FROM TIM JOHNSON TO VINCE KLCO ON 12/11/12 AT 1550 EST * * *

This notification retracts an eight (8) hour notification per 10CFR50.72(b)(3)(iv)(A) which was made December 2, 2012 and documented as NRC Event Notification (EN) # 48550. The December 2, 2012 actuation of the Auxiliary Feedwater System was initially reported under 10CFR 50.72(b)(3)(iv)(A), valid actuation of the Auxiliary Feedwater system as listed in paragraph 10CFR50.72(b)(3)(iv)(B)(6). McGuire Nuclear Station (MNS) has subsequently determined that the actuation signal, which was caused by a test signal during calibration of the AMSAC (Anticipated Transient Without Scram Mitigation Actuation Circuitry) actuation pressure switches, constitutes an invalid actuation as described in Revision 2 of NUREG-1022 (Event Reporting Guidelines 10CFR50.72 and 50.73). Specifically, valid actuations result from signals initiated in response to actual plant conditions or parameters satisfying the requirements for initiation of the safety function of the system. A test signal is not representative of an actual plant condition and was therefore an invalid actuation signal and does not meet the NRC 8-hour reporting criteria under paragraph 10 CFR50.72(b)(3)(iv)(B)(6). In addition to retracting the 10CFR50.72(b)(3)(iv)(B)(6) notification, MNS is notifying the NRC Operations Center that the December 2, 2012 event met the reporting criteria specified in 10CFR50.73(a)(2)(iv)(A). Specifically, an invalid actuation of the auxiliary feed water system occurred while the systems was in service. The event did not involve an actuation of the reactor protection system (RPS) when the reactor was critical; therefore, MNS is opting to notify the NRC Operations Center within 60 days in lieu of a 60 day written licensee Event Report (LER), as allowed by 10CFR 50.73(a)(1) and 10CFR50.73(a)(2)(iv)(A). This notification satisfies 10CFR50.73(a)(2)(iv)(A) reporting requirements in lieu of a written LER. The 2A and 2B trains of the auxiliary feed water were actuated by an invalid signal. Each train's actuation was complete and systems operated as designed. The licensee notified the NRC Resident Inspector. Notified the R2DO (Sykes).