05000498/FIN-2007007-07
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Finding | |
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| Title | Effect of Standby Diesel Generator Technical Specification Voltage Variation on Supplied Equipment |
| Description | The team identified an unresolved item associated with the steady state output voltage supplied by the standby diesel generators is allowed to vary by Technical Specification 3/4.8.1 from 3744 V to 4576 V (+/- 10%) during a loss of offsite power event. Specifically, the licensee has not analyzed for the effect of this full variation. The design analysis assumed maximum supplied voltage variations based upon offsite power supplies which were analyzed to vary less than the technical specification allowed steady state variation for the standby diesel generators. Components throughout the plant would be adversely affected by either an undervoltage or overvoltage condition. Since this is a very broad issue that encompasses components powered from the standby diesel generator during a design basis event, the licensee will require significant time to evaluate its effects. Although available safety margins will be less, the degree of this effect is not yet known since the effect of the variation varies upon the analyzed parameter and currently analyzed margins vary significantly. The actual safety function of equipment is not expected to be compromised since the standby diesel generators are presently controlled to a tighter band of voltage operation than allowed by technical specifications and review of the surveillance testing of the standby diesel generators confirms this tighter band is currently being maintained. Once the licensee has evaluated the effect of the allowed steady state voltage variation and determined the degree of safety margin impact throughout the plant, the NRC can complete the inspection of that analysis in order to close this issue. The licensee has documented this issue in Condition Record 07-15554 and the item is unresolved pending the licensees completion of its analysis and NRC review: URI05000498; 499/2007007- 07, Effect of Standby Diesel Generator Technical Specification Voltage Variation on Supplied Equipment. |
| Site: | South Texas  |
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| Report | IR 05000498/2007007 Section 4OA5 |
| Date counted | Mar 31, 2008 (2008Q1) |
| Type: | URI: |
| cornerstone | No Cornerstone |
| Identified by: | NRC identified |
| Inspection Procedure: | |
| Inspectors (proximate) | P Goldberg J Dixon G Werner R Latta B Correll W Schaupj Dixonb Tharakan S Graves J Adams W Walker W Sifre B Larson C Ryanh Andersonb Henderson S Rutenkroger W Sifre R Bywater J Chiloyan M Chambers G Apger S Makor |
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Finding - South Texas - IR 05000498/2007007 | |||||||||||||||||||||||||||||||||||||||||
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Finding List (South Texas) @ 2008Q1
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