ENS 46434
ENS Event | |
|---|---|
03:56 Oct 27, 2010 | |
| Title | Invalid Actuation Of High Consequence Limiting Safeguards And Safety Injection Systems |
| Event Description | This telephone notification is being made for an invalid actuation under 10 CFR 50.73(a)(2)(iv)(A) following the reporting guidance of 10 CFR 50.73(a)(1).
With Unit 1 at cold shutdown (about 105 degrees Fahrenheight and depressurized), an invalid actuation of the Unit 1 'A' train of the High Consequence Limiting Safeguards (HI CLS) system and Unit 1 'A' train of the Safety Injection (SI) system occurred at 23:56 during setup for 'H' Bus Logic Testing. Plant systems and components responding to the HI CLS and SI 'A' train signals started and functioned successfully as designed (with the exception of those systems and components procedurally rendered inoperable due to the RCS being below 350 degrees Fahrenheight and 450 psig). The HI CLS and SI 'A' trains were reset and the affected systems were restored to their pre-event configurations. Specific trains and systems that actuated for the 'A' train of HI CLS and SI are described below: - With the unit at cold shutdown, one high head pump was running (the two redundant pump controls were in the pull to lock position in compliance with Technical Specifications). The 'A' train High Head Safety Injection motor operated valves re-aligned such that the running high head pump provided flow to the RCS cold legs from the Refueling Water Storage Tank (RWST). During this time the pressurizer level increased from approximately 23 percent to about 42 percent. - Auxiliary Feedwater (AFW) Pump motor operated valves opened but no flow was delivered to the steam generators since the AFW pumps were in pull to lock. - The 'A' train containment isolation valves closed, isolating the 'A' Residual Heat Removal (RHR) heat exchanger. However, shutdown cooling was previously aligned to the 'B' train RHR and therefore shutdown cooling was uninterrupted. Containment isolation valves were later restored to a normal alignment. - One train of Auxiliary Ventilation actuated and was restored to normal after the Safety Injection signal was reset. - Emergency Diesel Generator (EDG) No. 1 started but did not load since its associated Emergency Bus remained energized by offsite power. The EDG was stopped and returned to automatic. An apparent cause evaluation is in progress. The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Surry  Virginia (NRC Region 2) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+658.58 h27.441 days <br />3.92 weeks <br />0.902 months <br />) | |
| Opened: | Jerry Ashley 15:31 Nov 23, 2010 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Nov 23, 2010 |
| 46434 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Not Critical |
| Scram | No |
| Before | Cold Shutdown (0 %) |
| After | Cold Shutdown (0 %) |
WEEKMONTHYEARENS 486622012-11-30T03:00:00030 November 2012 03:00:00
[Table view]10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid System Actuation ENS 486612012-11-29T04:05:00029 November 2012 04:05:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification of Invalid System Actuation ENS 464342010-10-27T03:56:00027 October 2010 03:56:00 10 CFR 50.73(a)(1), Submit an LER Invalid Actuation of High Consequence Limiting Safeguards and Safety Injection Systems ENS 447292008-10-29T23:04:00029 October 2008 23:04:00 10 CFR 50.73(a)(1), Submit an LER 60 Day Report - Invalid System Actuation 2012-11-30T03:00:00 | |