ML20211D404

Forwards Response to Ds Hood 870112 Request for Addl Info Re Surveillance Requirements for Cold Leg Accumulator Isolation Valves

ML20211D404
Person / Time
Site:	McGuire, Mcguire
Issue date:	02/13/1987
From:	Tucker H DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 8702200414
Download: ML20211D404 (6)

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DUKE POWER GOMPANY P.O. nox 33180 CHARLOTTE, N.O. 28242 HALH. TUCKER TELEPHONE vms ensamsar (704) 373-4531 wousam reonverms February 13, 1987 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C.

20555

Subject:

McGuire Nuclear Station Docket Nos. 50-369, 50-370 Gentlemen:

In response to Mr. D.S. Hood's request for additional information regarding surveillance requirements for the cold leg' accumulator isolation valves dated January 12, 1987, please find attached responses to the inquiries.

We believe this information is sufficient to complete review of the proposed amendment, however, if additional information is needed, please contact us through normal licensing channels.

As this submittal is in response to an NRC request and supplements an earlier proposal, no fees are enclosed.

Very truly yours, Hal B. Tucker JBD/173/j gm Attachment xc:

Mr. W.T. Orders NRC Resident Inspector McGuire Nuclear Station Mr. Darl Hood Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Dr. J. Nelson Grace, Regional Administrator U.S. Nuclear Regulatory Commission g

Region II 30 L 101 Marietta St. NW, Suite 2900 Atlanta, Georgia 30323 N\\\\

8702200414 870213 PDR ADOCK 05000369 P

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r DUKE POWER COMPANY McGUIRE NUCLEAR STATION RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION SURVEILLANCE REQUIREMENTS FOR COLD LEG ACCUMULATOR ISOLATION VALVES 1.

You state (incorrectly) that the proposed TS change is to allow the imple-mentation of planned modifications (i.e., installation of a power disconnect switch on the control board for the cold leg accumulator discharge isolation valves). We find.that the effect of the proposed TS change would be to provide for use of the design modification as the basis.for verifying that power to the isolation valve operator is disconnected, without additionally verifying removal of the breaker from the circuit. Provide a technical justification for your proposed request accordingly. Explain how the veri-fication required by the TS, as modified, would be accomplished.

Include in this discussion the conformance of the design modification to NRC Branch Technical Positions ICSB-4(PSB) and ICSB-18 (PSB).

Include electrical drawings and schematics as appropriate to support your technical discussion.

RESPONSE

Referring to MCEE-151-00.15, (attached) when the NI54/Close pushbutton is pressed contacts B5 and B6 close applying 120VAC control power to coil M/C.

This closes a set of contacts (M/C) in the 600VAC motor control center. If the valve does not cove to close position, this will signal that power disconnect circuit is in

. effect. Valve position can be confirmed by observing the green indicator light on E30JY5 control switch.

Conformance with NRC Branch Technical Position ICSB-4 (PSB) is assured as power is removed and the isolation valve is open. The position of the valve may be veri-fled from the control room as described above. Power is removed from the operator and would require deliberate operator action to restore power and move the valve, and no bypass is used for any testing as the valve is not required to move when the reactor coolant system is at pressure.

Conformance with NRC Branch Technical Position ICSB-18 (PSB) is assured as power is disconnected from the valve operator. With power removed from the operator and the valve in the proper (open) position, precludes any function of the valve, and, renders it a non-active valve.

As the valves are no longer active, no failure to function or undesirable function may occur. No operator action is required to assure desired performance of these valves under accident conditions.

The surveillance itself would be accomplished by depressing the power disconnect button, then pressing the close pushbutton. As discussed above, the valve would not move to the closed position with the power disconnect is in effect. Valve position is confirmed by an indicator light.

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2.

You state that the proposed change would not involve a significant increase in the probability or consequences of an accident previously evaluated because the installation of a power disconnect switch on the control board for the isolation valves would allow operators an alternative means of ensuring the operability of the accumulators.

Explain why the alternative means would not involve a significant increase in the probability or conse-l quences of an accident previously evaluated.

RESPONSE

i The surveillance requirement for the accumulators is intended to ensure the i

operability of the accumulators. The accumulators are part of the emergency core cooling system and will actuate only in the event of an accident. To mitigate the consequences of the accident, thus the operability of the accumulators does not affect the probability of an accident.

j To mitigate the consequences of an accident, the accumulators deliver a specified volume of borated water into the reactor coolant system to provide cooling water to the reactor core. The consequences of an accident would be unaffected as long as the volume of water delivered to the system is unaffected and the time for delivery is not increased. The power disconnect switch provides an alternate i

i s:eans to verify the operability of the system by assuring that the isolation i

valves are open with the power removed. The proposed change to-the Technical Specifications continues to require that power to the isolation valve operator is I

disconnected, but no longer specifies that it shall be done by removal of the

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breaker from the circuit, thus allowing the operators to make use of the new twitch, while assuring the valve is operable (open with power removed).

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3.

You state that the proposed change would not create the possibility of a new l

or different kind of accident from any accident previously evaluated because l

the only hardware change is to allow operators an alternative means of carrying out a surveillance that is presently required to ensure safety l

system operability. Explain why the alternative means would not create the possibility of a new or different kind of accident from any accident pre-l viously evaluated.

RESPONSE

The proposed change to the surveillance requirements would not affect the opera-l bility of the system. The isolation valves will continue to be verified open at least once per twelve hours in accordance with Specification 4.5.1.1.1.a.2 and 4.5.1.2.1.a.2.

The change would allow an alternative method of verifying that power to the isolation valve operator is disconnected.

U der the proposal, the n

isolation valve would be open with power removed from the operator, which forms part of the basis of system operability. No functional changes to the system are cade that would affect system operability.

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. 4.

You state that the proposed change would not involve a significant reduction in a margin of safety because the installation of a power disconnect switch on the control board for the isolation valves would allow an alternate means for meeting a required surveillance and would not affect any safety margins.

Explain why the alternate means would not affect any safety margins.

RESPONSE

The proposed change would not affect the surveillance requirement requiring the isolation valve to be open, and neither would it affect the requirement that power be removed from the valve operator, merely allowing a different method for veri-fying that power is removed from the valve operator.

Therefore, there is no increased chance that coolant flow from the accumulator into the Reactor Coolant system will be impeded by this change. Margins assumed in terms of coolant volume and time to deliver are unaffected.

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