ML20056C367
| ML20056C367 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 05/12/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20056C346 | List: |
| References | |
| NUDOCS 9305200269 | |
| Download: ML20056C367 (1) | |
Text
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f 2.0 LIMITING CONDITIONS FOR OPERATION 2.7 Electrical Systems (Continued)
I k.
Island buses IB3A-4 A, IB3B-4B, and IB3C-4C may be inoperable for up
'i to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> provided there are no inoperable safeguards components which are redundant to components on the inoperable bus (es).
1.
Either one of the 125V d-c buses No.1 or 2 (Panels EE-8F or EE-8G)
{
may be inoperable for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
Either one of the 125V d-c distribution panels Al-41 A or AI-41B may be
[
m.
inoperable for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
l Either one of the 120V a-c instrument panels AI-42A or AI-42B may be n.
inoperable for up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
j Basis The electrical system equipment is arranged so that no single failure can inactivate enough engineered safeguards to jeopardize the plant safety. The 480 V safeguards are arranged on nine bus sections. The 4.16 kV safeguards are supplied from two buses.
The normal scurce of auxiliary power with the plant at power for the safeguards buses is from the house service power transformers being fed from the 161 Kv incoming line with on-site emergency power from either one of two diesel generators and off-site standby power via the unit auxiliary transformers.m The loss of the 161kV incoming line j
renders the house service transformers (TIA-3 and TIA-4) inoperable in that the transformers cannot supply power to the 4.16kV safeguards buses IA3 and 1A4.
Inoperability of the house senice transformer (s) or loss of the 161kV incoming line is not reportable pursuant to 10 CFR 50.72 criteria; however, the NRC will be promptly
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notified of these events via the NRC Operations Center.
The two emergency diesel generators on site do not require outside power for start up or operation.
Upon less of normal and standby power sources, the 4.16 Kv buses IA3 and IA4 are energized from the diesel generators. Bus load shedding, transfer to the diesel generator and pickup of critical loads are carried out automatically."
When the turbine generator is out of service for an extended period, the generator can be isolated by opening motor operated disconnect switch DS-Tl in the bus between the generator and the main transformer, allowing the main transformer and the unit auxiliary power transformers (Tl A-1 and TI A-2) to be returned to service.* The auxiliary power transformers are not considered inoperable during these normal plant startup/ shutdown realignments.
P 2-35 Amendment No. MrMh150 9305200269 930512 PDR ADOCK 05000285 i
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