05000250/FIN-2017007-10
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Finding | |
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| Title | Potential failure of 125 Vdc Bus 3B Class 1E components |
| Description | UFSAR Section 8.2.2.3.1 stated that the emergency power for vital instrumentation and controls is supplied by a station DC power system which contains five safety related 125Vdc batteries and four DC distribution panels. 125 Vdc distribution panel 3B supplies safety related power to several safety-related equipment including sequencers, reactor trip switchgear, inverter 3Y06, and control power to 480Vac load centers 3B and 3D and 4160 Vac switchgears 3AB01 and 4AB20. UFSAR Section 7.2 stated that the reactor protection system was designed in accordance with IEEE 279- 1968. Section 4.5 of IEEE 279-1968, Channel Integrity, requires all protection system channels be designed to maintain necessary functional capability under extremes of conditions relating to malfunctions. During the review of calculation 5177-265-EG-22, Circuit Breaker/Fuse Coordination Study, Rev. 8, the team questioned if there were instances where class 1E cables associated with DC Bus 3B (3D23) would not be adequately protected given a short circuit on the load side of the breakers. The failure to ensure the Class 1E protective devices would not allow the maximum available short circuit to permanently damage cabling to safety-related equipment associated with DC Bus 3B could result in additional loss of Class 1E equipment. Unresolved Item (URI)05000250/2017007-01 and 05000251/2017007-01, Potential failure of 125 Vdc Bus 3B Class 1E components,) is opened for additional review to determine if the Class 1E cables on DC Bus 3B can withstand the maximum possible short circuit and to determine if a performance deficiency exists. |
| Site: | Turkey Point  |
|---|---|
| Report | IR 05000250/2017007 Section 1R21 |
| Date counted | Sep 30, 2017 (2017Q3) |
| Type: | URI: |
| cornerstone | Initiating Events |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21M |
| Inspectors (proximate) | T Fanelli S Bussey M Riley N Morgan M Jones H Leake R Bywater J Bartley |
| INPO aspect | |
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Finding - Turkey Point - IR 05000250/2017007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Turkey Point) @ 2017Q3
Self-Identified List (Turkey Point)
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