ENS 43031
ENS Event | |
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18:25 Dec 4, 2006 | |
Title | Potential Defective Woodward Governor for Fairbanks Morse Edg |
Event Description | South Carolina Electric & Gas Company makes the following notification under 10 CFR 21.21(d)(3)(i) of a defect found during pre-installation testing of a Fairbanks Morse Woodward 2301 A/DRU governor. This governor was not installed on the Virgil C. Summer Nuclear Station Emergency Diesel Generators (EDG).
The Fairbanks failure mode effect analysis (FMEA) states that when 125 VDC power is lost to the governor Digital Reference Unit (DRU), the speed reference signal goes to 0 VDC and that the Control Module will respond to drive the EDG to rated speed of 514 rpm. When this failure mode was tested, removal of the 125 VDC power resulted in a speed reference signal of -4 VDC. This would result in the governor Control Module driving the EDG to the low speed set point of 300 rpm. The failure to achieve rated speed would prevent the EDG from performing its safety function. Following a loss of 125 VDC power, the DRU must be manually reset in order for the Control Module to drive the EDG to rated speed. Users of this governor, that are not aware of this failure mode, may be unaware that the in-service EDG would be unable to meet the Technical Specification requirements unless surveillance tests were performed following the loss of power. The licensee will notify the NRC Resident Inspector. |
Where | |
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Summer South Carolina (NRC Region 2) | |
Reporting | |
10 CFR 21.21 | |
Time - Person (Reporting Time:+19.45 h0.81 days <br />0.116 weeks <br />0.0266 months <br />) | |
Opened: | Charles Mckinney 13:52 Dec 5, 2006 |
NRC Officer: | Joe O'Hara |
Last Updated: | Dec 5, 2006 |
43031 - NRC Website
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Unit 1 | |
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Reactor critical | Critical |
Scram | No |
Before | Power Operation (100 %) |
After | Power Operation (100 %) |
WEEKMONTHYEARENS 469972011-06-27T20:11:00027 June 2011 20:11:00
[Table view]10 CFR 21.21 Appendix R Analyses Fails to Recognize Hot-Short Failure Resulting in the Loss of an Essential Electrical Bus ENS 430312006-12-04T18:25:0004 December 2006 18:25:00 10 CFR 21.21 Potential Defective Woodward Governor for Fairbanks Morse Edg 2011-06-27T20:11:00 | |