05000336/FIN-2013004-04
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Finding | |
|---|---|
| Title | Licensee-Identified Violation |
| Description | TS 3.8.2.1 requires, in part, that when 480V Emergency Load Center 22E is inoperable, it must be restored to operable status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or be in COLD SHUTDOWN within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Contrary to the above, from initial construction until June 8, 2012, the bus 22E was inoperable due to a gap in the HELB barrier. This gap would allow high energy steam to enter the switchgear rooms, causing the electrical equipment inside to potentially fail. The inspectors determined that there was a performance deficiency in that Dominion did not recognize the inoperability of the 22E bus as a result of the historical gap and take the appropriate actions as required by TS. This finding is of very low safety significance as determined by a detailed risk assessment using SAPHIRE 8 and a modified main steam line break outside of containment event tree from the Millstone 2 SPAR model. Specifically, the risk analysis reviewed three possible main steam line break sources in the turbine building near the West 480V Switchgear Room. The assumed one year exposure period was broken down into a period of 66 days when alternate cooling was in effect for the West 480V Switchgear Room and two days when it was in effect for the East 480V Switchgear Room. The frequencies of the associated steam line breaks were determined from a recent EPRI steam line break technical report, given the assumed leak location and the estimated length of associated piping. With the gaps in the HELB barrier and assuming a steam line break, the West 480V switchgear was assumed to fail. When alternate cooling was used for the West 480V Switchgear Room, if the steam line was not isolated, both trains of DC switchgear were also assumed to fail due to high temperature/humidity. When the East Switchgear alternate cooling was used, it was assumed that failure of all safety-related 480V power would have occurred due to high temperature/humidity. Dominion sealed the gap upon discovery in June 2012 and has entered this issue into the CAP (CR478194). |
| Site: | Millstone  |
|---|---|
| Report | IR 05000336/2013004 Section 4OA7 |
| Date counted | Sep 30, 2013 (2013Q3) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | M Patel M Modes B Haagensen J Krafty R Mckinley J Nicholson R Rolph S Chaudhary J Ambrosini T Hedigan D Lawyer |
| Violation of: | Technical Specification |
| INPO aspect | |
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Finding - Millstone - IR 05000336/2013004 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Millstone) @ 2013Q3
Self-Identified List (Millstone)
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