ML19319A870
| ML19319A870 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/22/1967 |
| From: | Danielle Sullivan US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Long C US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7912191047 | |
| Download: ML19319A870 (2) | |
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2/femorandum C. G. Long, Chief DATE: IMY ? ' 1%/
Reactor Pro g ranch #3, DRL TilRU:
V. A.-
Chief, Instrumentation and Power Technology Branch, DRL 4,h od N
D. F. Sullivan.
Instrumentation ana Power Technology Branch, DRL
$UBJECT: DOCKET NO.. 50-269/270:
UCONZE (DUKE) NUCLEAR STATION,
.ON-SITE ENERGENCY POWEP UNITS #1 AND #2 3
I&PTB:DRL:DFS RT-20 On May 8, 1967, R. L. Ferguson, H. Denton, and I tet
...a represet.scives of the Duke Power Company and Babcock and Wilcox te discuss the safety aspects of off-site and on-site emergency power at the proposed Oconce station, Units 1 and 2.
This memo deals only with the on-site power.
Up-to-date full size drawings of " Electrical Power Systems - Singic Line Diagram" (Fig. 6-1, PSAR), and "125/250 VDC System and 120 VAC Vital Pouer System" (Fig. 8-3, PSAR) were r.:ade availabic to us.
In addition, we also received a draft copy of revised answers to several staff questions pertaining to the emergency electrical systems.
Units #1 and #2 will share four 125 VDC batterica and six outtery chargers.
One pair of batteries will feed one three-wire aus (250/125/0), and the other pair will feed a second three-wire bus.
In general, control and instrumentatica loads will be supplied at 125 volts de, with tue heavier loads such as motors supplied at 230 volts dc.
The de system is ungroundeu.
Six separate 125 volt de control power panelboards will be provided.
1:.ach panclboard will be supplied by redundant feeders from dif farent 123/250 volt de bus sections through diodes to isolate Ony faults which might occur on one of the feeders.
Mr. C. Wylie, of Duke Pouec, assured us that a method will be devised for testing the diodes during reactor operation.
detailed failure analysis of the three-wire de system has been presented A
in Supplement 2 of-the PSAR, and is presently being rcvfewed.
All of the ac power sources will supply power through transformers to the redundant 4160 volt main feeder busces and tie circuit breakers whica supply power to the redundant 4160 volt switchgear bus sections that serve the engineered safeguard auxiliaries and reactor protection systems.
The engineered safeguard l auxiliaries and reactor protection systems will be arranged so that a failure of any single bus sectien will not prevent tne respective systems from fulfilling their protection functions. The emer-gency' power sources will be automatically switched onto the 4160 volt main c =,
-feeder buses of a'unic.in the preferential sequence as follows:
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the startup transformer bus b) the other unit's auxiliary electrical systcm c) the 100 Kv transmission line d)~ the Keowce Hydro station The control schemes will be designed to prevent the paralleling of two sources during the above switching operations.
k'e expressed concern over the possibility of failure of this switching system.
There were no circuit diagrams available te ut. and no fault analysis of the system has been submitted.
- .'e we rc.
,.d that the system will be designed to tneet tae single failure cr_erion.
Shedding of nonessential loads will be accomplished via circuit braab rs with duplicate trip coils energized from different de buses.
Presuncbly.
those feeder breakers whose closing is essential to plant safety uncer accident conditions are arranged to meet the single faibire criterien, whether the f ailure is electrical or mechanical. This is being cvaluated by us at present.
Four redundant 120 volt ac vital instrument power buses will be provided to supply power to essential instrumentation and control loads under all operating conditions.
Each bus will be supplied separately from a static inverter connected to one of the six 125 de control power panelboarus.
In addition.. sources of 120 volts ac (regulate :) cnd 120 y 208 volt ac (unregulated)will be available.
IIr. h'ylie agreed to provide in-service testin? capability to determine if a battery (er batteries) has become disconnected.
cc:
S. Levine, Asst. Dir., DRL V. A. Moore, DRL D. Grines, DRL D. F. Sullivan 9
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