ML20086N848
| ML20086N848 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 12/12/1991 |
| From: | Mcmeekin T DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9112240313 | |
| Download: ML20086N848 (3) | |
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IJcGuin Nactrar Generation i)<partment th e fusident liioollagers ferry Road (SIGGIA) tilH)SI!4h00 fluntersnile, NC Zb0iM9b5 (IU41!T4M9 Ik' DUKE POWEFl December 12, 1991 U.
S.
Nuclear Regulatory Commission Attention Document Control desk Washington, DC 20555
Subject:
McGuire Nuclear Station Docket Nos. 50-369, -370 EDSFI TEAM INSPECTION REPORT 91-09 Supplemental Response to Finding on EPL System Circuit Breaker Coordinaticn Gentlemen:
The above NRC Inspection Report found that the 125 VDC Vital Instrumentation and Control (EPL) system is not selectively coordinated above a certain level of fault current.
Since the system is shared between both McGuire Units 1 and 2, this could potentially result in a trip of both units if this specif1.c fault were to occur.
A September 27, 1991 letter to the NRC addressed plans and a schedule to resolve the finding.
Those plans and schedule included replacing the charger, battery, main and cross-tie circuit breakers with fusible and non-fusible switches.
Since then, review found it would not be necessary to
. replace the charger circuit breakers because of their internal current limiting feature.
As noted in the 9/27/91 letter, the feasibility of panelboard changes would be addressed in this succeeding letter.
It has been determined that the original plan with the above exception is appropriate and the best alternative.
As plannad, replacing the circuit breakers with fuses will allow the protective devices closest to the fault to clear before isolating the battery from the bus.
This will decrease the possibliity of a fault causing a loss of power which could trip both units.
In the cross-tied configuration, the fuses will help insure that the' bus without a battery will be cleared successfully under a fault condition without isolating the battery from the unfaulted bus.
F1122iU312 911212 f
PDR ADOCK 05000369
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Nuclear Regulatory Commission I
December 12, 1991 Page 2 Regarding the DC Panelboard, the FSAR postulates the consequences of a fault on a panelboard.
It states the panelboard will be isolated and the other train will be used for shutdown.
This modification will enhance that response by preventing a fault on j
the panelboard of one unit from propagating to effect *he other unit panelboard.
The original time schedule is not effected by this response.
If you have questions, please contact Kathloon Mullen at (704) 075-4302.
Very truly yours, ffoYY T. C. McMeekin xc:
S.
D.
Ebneter, Regional Administrator U.
S.
Nuclear Regulatory Commission, Region II 101 Marietta Street, NW Suite 2900 Atlanta, GA 30323 T.
A.
Reed, Projects Manager Office of Nuclear Reactor Regulation U.
S.
Nuclear Regulatory Commission Washington, D. C.
20555 P.
K. VanDoorn Sr. Resident Inspector Nuclear Regulatory Commission McGuire Nuclear Station
bcct A.
V. Carr-Counsel PB05E M. Sample-GO Safety Assurance R. L. Gill, Jr.-GO Safety Assura,nce D.
R. Bradshow-WC25A T. L. McConnell G. D. Gilbert P. R. Herran A..C.
Williams W. N. Matthews K.
D.- Thomas J.
E. Stoner K.
P. Mullen R. O. Sharpe MNS Master file 1.2.1, Ref. IE 91 09 MC-815.01-GO MC-015.01-MNS
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