05000390/FIN-2016011-05
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Finding | |
|---|---|
| Title | Common Service Station Transformers A and B General Design Criteria 17 Analyses |
| Description | The team identified an unresolved item (URI) related to the licensees analyses done to evaluate the use of common service station transformers (CSST) A and B as qualified offsite circuits that satisfy general design criteria (GDC) 17. This URI is to determine if a performance deficiency exists. The Class 1E power system is normally supplied from offsite power through CSST C and D. Watts Bar applied for and was issued a license amendment to, in part, add an allowance to use CSST A or B as qualified offsite circuits that satisfy GDC 17. During the review of the license amendment, the NRC requested additional information about when CSST A or B is being used as a GDC 17 source and the auxiliary systems for both units are powered from the main generator. By letter dated January 29, 2015, the licensee replied by stating, in part, that their analysis evaluated: a.) A dual unit trip as a result of abnormal operational occurrence; and c.) Accident in one unit and spurious ESF actuation in the other unit. The team has requested the licensees analyses for scenarios a.) and c.) from the licensees response and has questions about how the licensee accounted for the voltage drop due to fast transfer of loads from the main generator to CSST A or B. This issue will remain open pending the licensees response to the teams questions and subsequent review in order to determine if a PD exits. This URI is identified as 05000390, 391/2016011-05 Common Service Station Transformers A and B General Design Criteria 17 Analyses. |
| Site: | Watts Bar  |
|---|---|
| Report | IR 05000390/2016011 Section 1R21 |
| Date counted | Sep 30, 2016 (2016Q3) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | C Franklin C Smith H Leake J Bartley J Eargle M Greenleaf M Yeminy |
| INPO aspect | |
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Finding - Watts Bar - IR 05000390/2016011 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Watts Bar) @ 2016Q3
Self-Identified List (Watts Bar)
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