ENS 49666
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ENS Event | |
|---|---|
04:33 Dec 20, 2013 | |
| Title | Valid Actuation of Main Steam Isolation Valves That Was Not Part of a Preplanned Sequence |
| Event Description | While in Mode 3 in preparing the Unit 2 secondary plant for startup, conditions occurred where it became necessary to break vacuum on the main condenser. Procedures directed closing of the main steam isolation valves. Instead of shutting each main steam isolation valve individually, a manual main steam isolation actuation was initiated through the solid state protection system (SSPS) to close the valves. This actuation of SSPS was a valid signal. The actuation was not part of a preplanned sequence.
This notification is supported by the guidance of NUREG-1022, Revision 3, 'Event Reporting Guidelines 10CFR50.72 and 50.73.' In part, the guidance states: 'The Commission is interested in both events in which a system was needed to mitigate the consequences of an event (whether or not the equipment performed properly) and events in which a system actuated unnecessarily.' The manual actuation was not initiated to mitigate the consequences of an actual event. However, the method of closing the main steam valves for this condition did not specifically require that the valves should be closed by initiating a main steam isolation signal and therefore, the safety system was unnecessarily actuated. Therefore, this notification is being made pursuant to 10 CFR 50.72(b)(3)(iv)(A) as an event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B) that was not part of preplanned sequence during testing or reactor operation. The system listed in paragraph (b)(3)(iv)(B) is (2) main steam isolation valves. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
South Texas  Texas (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+6.83 h0.285 days <br />0.0407 weeks <br />0.00936 months <br />) | |
| Opened: | Robert J. Lane 11:23 Dec 20, 2013 |
| NRC Officer: | Vince Klco |
| Last Updated: | Dec 20, 2013 |
| 49666 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Hot Standby (0 %) |
| After | Hot Standby (0 %) |
WEEKMONTHYEARENS 568772023-12-02T12:10:0002 December 2023 12:10:00
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