05000289/FIN-2012007-05
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Finding | |
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| Title | Licensee-Identified Violation |
| Description | 10 CFR Part 50, Appendix B, Criterion lll, Design Control, requires in part, that design control measures provide for verifying or checking the adequacy of design, Contrary to this, design control measures had not ensured and verified that connected Class 1E loads are not damaged or become unavailable for a design basis event concurrent with a degraded voltage condition between the 4kV degraded voltage dropout setting and the loss-of-voltage setting, prior to and following transfer to the EDG onsite source. Exelon had previously identified in early 2009, within AR 838100, that actions were required to review their design at TMI with respect to the selection and sizing of TOLs which were not bypassed on an accident signal. This included proposed actions to review the long time trip of protective relays and the impact of extended duration of locked rotor current on potential motor damage from additional heating. Additionally, Exelon identified in December 2011 within AR 1276061, the need to review the design to verify the allowable degraded voltage relay (DVR) time duration would not result in failure of safety-related systems or components. The finding was of very low safety significance (Green) because the finding did not represent the loss of a system salety function, an actual loss of safety function of a single train for greater than the TS allowed outage time, or screen as potentially risk significant due to a seismic, flooding, or severe weather initiating event. Exelon initiated AR 1347885 to ensure all aspects of the design issue will be resolved based on additional comments from the inspection team. |
| Site: | Three Mile Island  |
|---|---|
| Report | IR 05000289/2012007 Section 4OA7 |
| Date counted | Mar 31, 2012 (2012Q1) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | J Lilliendahl J Schoppy F Arner J Brand J Nicely L Doerflein C Edwards |
| INPO aspect | |
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Finding - Three Mile Island - IR 05000289/2012007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Three Mile Island) @ 2012Q1
Self-Identified List (Three Mile Island)
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