ML19250C652
| ML19250C652 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 10/30/1979 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19250C651 | List: |
| References | |
| NUDOCS 7911280541 | |
| Download: ML19250C652 (1) | |
Text
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STAFF POSITION PEACH BOTTOM UNIT NOS. 2 AND 3 DEGRADED GRID VCLTAGE Our letter dated June 2,1977 included Staff Position 1 which states that the voltage monitors shall be designed to satisfy the requirements of IEEE 279-1971. The intent of this position is that the monitors provide undervoltage protection of the ESF load. The monitors are to be part of the Class IE distribution system.
The licensee proposed modification would monitor the 13 KV line as opposed to monitoring the 4160 V emergency bus. This proposal is considered to be monitoring of an indirect variable, does not directly monitor degraded voltage condition on the emergency bus and hence is not acceptable.
Degradation of the emergency bus voltage can occur due to a number of causes that would not necessarily be reflected on the 13 KV line. Therefore, direct monitoring of the' voltage on the emergency bus is required to protect ESF loads against degrading voltages.
The licensee should modify his scheme to meet all the staff positions stated in the NRC letter dated June 2, 1977.
1410 343 9
7911280 $ V /