ML20138R944
| ML20138R944 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 11/06/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8511190286 | |
| Download: ML20138R944 (2) | |
Text
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DUKE POWER GOMPANY P.O. ISOK 33180 CitAHLOTTE. N.C. 28242 HALH. TUCKER rzternoxz TRES perSIDSWT -
(704) 373-4531 mannaa enopverson November 6, 1985 Dr. J. Nelson Grace, Regional Administrator 5
U. S. Nuclear Regulatory Commission y
Region II 101 Marietta Street, NW, Suite 2900 Atlanta,-Georgia 30323 o
Subject:
McGuire Nuclear Station C.c IE Inspection Report 50-369/84-28 and 50-370/84-25
.t.
Dear Dr. Grace:
Duke would like to clarify a statement made in a letter dated August 8, 1985 from NRC to Duke relative to subject inspection report. On page 3 of this letter, the NRC states that,:
"The RHR Isolation valves are made inoperable during normal operation by opening their respective power breakers" Duke Power takes credit for the number and location of the valve control circuit interlocks tc' preclude spurious operation (Attachment I).
Valve
-FW27A, which provides one of the open inhibit interlocks to ND1B and ND2A, is locked open during plant operation. Additionally, since these valves are maintained in the required shutdown position during plant operation and motive power is not required, the valves are not affected by lack of breaker coordin-ation on the associated busses.
These circuits were reviewed in detail during the NRC onsite audit as addressed in the subject inspection report.
Unless informed to the contrary, Duke considers that the discussion provided herin by Duke is acceptable to the NRC.
Very truly yours,
(.
Hal B. Tucker f'
RLG/hrp -
cc:
Mr. Darl Hood, Project Manager Mr. W. T. Orders Division of Licensing NRC Resident Inspector Office of Nuclear", Regulatory Commission McGuire Nuclear Station Washington, D. C.'20555 i
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J Valves 1CA161C and 1CA162C (i.e., Unit 1 only) and portions of associated cabling are physically located in fire areas 4 (Auxiliary Building 716+0) and 14 (Auxiliary Building 733+0), i.e., the same fire areas as redundant, safe shutdown components and cabling of the normal shutdown systems (e.g.,
Centrifugal Charging Pumps 1A and 18).
ICA161C and ICA162C are provided to align the Turbine Driven Auxiliary Feedwater Pump to an assured source of RN water during SSS operation and must be maintained free from fire damage.
These design nonconformances were initially reported to the NRC on July 18, 1984, as documented in Non-Routine Event Report #1-84-34.
Subsequently, Duke Power has committed to wrap the valves and associated cabling in a three hour fire insulating blanket, to i'nsure SSS shutdown capability in fire areas 4 and 14.
Fire Areas 22 and 23:
Cabling associated with SSS-related steam generator C level instrumenta-tion is located in fire areas 22 (Unit 1) and 23 (Unit 2).
Each SSS dedicated transmitter is separately fused at amp with a Bussman FNA type fuse and the 24VDC power supply has a current limiting device rated at 13 amps.
Thus, fuse coordination will insure the integrity of the power Steam' generator level monitoring for three steam generators and source.
SSS shutdown capability for fire areas 22 and 23 is assured.
3.
Results:
Spurious Component Operation Review 3.1 RCS/RHR Boundary Valves Of concern is whether a fire in one of the subject plant areas (e.g.,
Control Complex) could cause the RCS/RHR boundary valves to spurious-ly open prior to RCS depressurization to 350 PSIG.
Once aligned for standby shutdown system operation, the controls and power for one RHR suction valve are fully isolated from the control room to preclude spurious operation.
Spurious operation of both valves prior to SSS alignment is considered an incredible event by virtue of the location and number of control circuit interlocks.
The open circuit for each RHR suction valve contains in series a control switch contact, a pressure interlock contact, and valve position interlock contacts.
The pressure interlock and valve position interlocks both inhibit opening of the valve under normal operation.
The control switch location, pressure interlock cabinets, and valve limit switches are spatially separate.
The valve position interlocks originate from outside the control room and cannot be bypassed by a short in the control room.
a 3.2 RCS Boundary Valves & Centrifugal Charging Of concern is whether a fire in one of the subject plant areas could, within the first ten minutes prior to SSF alignment, cause RCS bounda-ry valves to spuriously open and also damage power cables to both of the Centrifugal Charging Pumps (Train A & B).
EL40119A/38