ML20084L189
| ML20084L189 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/08/1984 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8405140375 | |
| Download: ML20084L189 (3) | |
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DUKE POWER GOMPANY P.O. HOX 33180 CHARLOTTE N.C. 28242 HALB. TUCKER reternoxe vua ram nermy (704) 373-4531
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- May 8, 1984
- Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4 t-Re: Catawba Nuclear Station Docket Nos. 50-413 and 50-414
Dear Mr. Denton:
My letter of April 11, 1984 transmitted a review of associated circuits pursuant to Appendix R for the Catawba Nuclear Station. The attached information supple-ments this previous' submittal.
Very truly yours, sl'/$/e r
Hal B. Tucker ROS/php Attachment cc: Mr. James P. O'Reilly Palmetto Alliance Regional Administrator 21351 Devine Street U. S. Nuclear Regulatory Commission Colurabia, South Carolina 29205 Region II
. 101 Marietta Street, NW, Suite 2900 Mr. Jesse L. Riley Atlanta, Georgia 30303 Carolina Environmental Study Group 854 Henley Place NRC Resident Inspector Charlotte, North Carolina 28207 Catawba Nuclear Station Mr. Robert Guild, Esq.
Attornoy-at-Law P. O. Box 12097 5
Charleston, South Carolina 29412 8405140375 e4050s fDRADOCK 05000413 PDR g
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1 CATAWBA NUCLEAR STATION Additional Infonnation Pursuant to Appendix R Analysis I.
Objective To provide assurance that the high pressure / low pressure interface,
between the Reactor Coolant System and the Residual Heat Removal System is not breached due to spurious valve operation resulting from a fire.
Approach Duke Power will maintain the motor control center breaker tripped to one of the two series valves in each of the two parallel RHR suction lines during normal power operation.
II.
Scenario Assuming a fire in a fire area containing cables of all three shutdown divisions, is it possible to experience concurrent faults on the available shutdown division cables which would not trip the individual feeder breakers, but whose total combined current could trip upstream incoming breakers which also provide power to other needed shutdown equipment outside the fire area.
Approach Breaker / fuse coordination was analyzed on the available shutdown division using the following assumptions and methodology.
A.
600 VAC Power System-
- 1) Electric Motor Operated (EM0) Valve Circuits a)
Each EM0 valve power circuit routed in the fire area was assumed to operate at a value equal to locked rotor current on the motor.
This approach'is very conservative since:
l
- 1) The power cable from the motor starter to the valve motor is not normally energized, i.e., power is applied only when the valve is j
cycling.
- 2) The contrcl circuit was assumed to fail such that
-The valve was called on to cycle, and
-The power circuit was not opened when the valve completed its' L
travel, thus the motor would be subjected to locked rotor current.
This condition would cause motor failure in a very short time and should result in tripping the associated feeder breaker.
b)
Each EM0 valve power circuit not in the fire area was assumed to be de-energized since power is applied only during valve cycling.
~ _ -
c.
. J'
- 2) All Non-EM0 Valve 1.oad Circuits a)
Each non-EM0 valve power circuit routed in the fire area was assumed to have a high impedance fault equal to its feeder breaker continuous current rating. This approach is very conservative as the overload heaters in motor starter circuits would initiate tripping for values considerably below the assumed values.
~
b)
Each non-EMO valve power circuit not routed within the fire area l
was assumed to be supplying power to the connected load.
The total assumed current associated with eaci, available shutdown division Motor Control Center (l1CC) bus (the sum of 1 and 2 above) was used to verify the MCC would not trip for the postulated conditions.
B.
120 VAC/125 VDC Power System
- 1) All of the ~ circuits in the affected fire area were assumed to have f
concurrent high-impedance faults with currents drawn being just
~ below the trip point of the protective device.
- 2) The upstream protective device was assumed to supply the above described fault current plus other normal connected full load currents of circuits unaffected by the fire.
-3) The duration of the faults was analyzed for five minutes which was the maximum time covered by the available fuse curves.
Conclusion We have reviewed breaker / fuse coordination for the available shutdown divisions using the above approach and verified the buses providing power to other shut-down equipment outside the fire area will not be tripped for the postulated conditions.
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