ENS 48113
ENS Event | |
|---|---|
14:20 May 24, 2012 | |
| Title | 60 - Day Optional Telephone Notification of an Invalid Division 2 Containment Isolation Signal |
| Event Description | This 60-day telephone notification is being made per the reporting requirements specified in 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(3)(1) to describe an invalid actuation signal affecting containment isolation valves in more than one system.
On May 24, 2012, Nine Mile Point Unit 2 (NMP2) received a Division 2 primary containment isolation signal which resulted in closure of Group 3, 8, and 9 primary containment isolation valves (PCIVs) in the following systems: Group 3 PCIVs: Traversing Incore Probe (TIP) ball valves (the TIPS were already withdrawn and the ball valves were already closed); nitrogen purge to TIP indexing mechanism. Group 8 PCIVs: Reactor building closed loop cooling system; drywell equipment drain system; drywell floor drain system; instrument air system; hydrogen recombiner system; containment monitoring system; reactor recirculation system flow control valve hydraulic system; containment leakage monitoring system. Group 9 PCIVs: Containment purge system (the containment purge valves were already closed). All affected PCIVs responded as designed. In addition, the Division 2 containment isolation signal resulted in isolation of the Reactor Building normal ventilation system, starting of the Division 1 and Division 2 standby gas treatment subsystems, starting of the Division 1 and Division 2 Reactor Building safety-related unit coolers, and starting of the Division 2 Control Room envelope filtration subsystem. The Division 2 isolation signal was generated during a maintenance activity involving the replacement of a relay in a main control room panel. During the activity, an installed jumper became dislodged from its point of origin, leading to a blown control power fuse and generation of the Division 2 isolation signal. Since the isolation signal was not initiated in response to actual plant conditions or parameters satisfying the requirements for initiation, the isolation signal was determined to be invalid. This event was entered into the corrective action program as Condition Report (CR) 2012-005128. There were no safety consequences or impact on the health and safety of the public as a result of this event. The Licensee has notified the NRC Resident Inspector. |
| Where | |
|---|---|
Nine Mile Point  New York (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1297.78 h54.074 days <br />7.725 weeks <br />1.778 months <br />) | |
| Opened: | Carl Crawford 16:07 Jul 17, 2012 |
| NRC Officer: | Bill Huffman |
| Last Updated: | Jul 17, 2012 |
| 48113 - NRC Website | |
Unit 2 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 535842018-03-19T04:00:00019 March 2018 04:00:00
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