ENS 48661
ENS Event | |
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04:05 Nov 29, 2012 | |
Title | 60-Day Optional Telephonic Notification of Invalid System Actuation |
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) and is not considered a Licensee Event Report.
With Unit 2 at Cold Shutdown (about 105?F and depressurized), an invalid actuation of the Unit 2 'A' train of the High High Consequence Limiting Safeguards (Hi-Hi CLS) system occurred at 2305 [EST] during reinstallation of fuses in preparation for return to service testing. The fuses were pulled to implement a design modification to replace existing relays with a new design. The 'A' train of the High High CLS actuated as soon as the fuses were installed. Plant systems and components responding to the Hi-Hi CLS '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?F and 450 psig. Shutdown cooling was not lost due to safety injection leads being tagged out. The signal could not be reset from the Main Control Room due to system design in this configuration requiring manual local manipulations to address affected components. The relays on both trains were replaced with the original design and the fuses reinstalled. The affected systems were restored to their pre-event configuration. Specific trains and systems that actuated as a result of the "A" train of Hi-Hi CLS signal are described below: -- Component Cooling from the A Reactor Coolant Pump isolated. -- Containment Spray realigned and gravity flowed the Refueling Water Storage Tank and Caustic Addition Tank to the Containment Sump. The level did not reach the point where any components in the containment basement were affected. -- Service Water flowed to the A and C Recirculation Spray Heat Exchangers. -- Containment Instrument Air isolated. -- Emergency Diesel Generator (EDG) No.2 started but did not load since its associated Emergency Bus remained energized by offsite power. The EDG was stopped and returned to automatic. A root cause evaluation is in progress. The licensee notified the NRC Resident Inspector |
Where | |
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Surry Virginia (NRC Region 2) | |
Reporting | |
10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
Time - Person (Reporting Time:+1014.88 h42.287 days <br />6.041 weeks <br />1.39 months <br />) | |
Opened: | Barry Garber 10:58 Jan 10, 2013 |
NRC Officer: | Donald Norwood |
Last Updated: | Jan 10, 2013 |
48661 - NRC Website
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Unit 2 | |
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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 | |