ML20010A382

Submits Justification of Licensing/Engineering Dept Determination That Mod of Main Feedwater Valve Circuits Is Not Necessary.Diagrams Encl

ML20010A382
Person / Time
Site:	Beaver Valley
Issue date:	08/06/1981
From:	Carey J DUQUESNE LIGHT CO.
To:	Varga S Office of Nuclear Reactor Regulation
References
DCP-451, TAC-42722, TAC-44830, NUDOCS 8108110378
Download: ML20010A382 (5)

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August 6, 1981 15219 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission

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Mr. Steven A. Varga, Chief 4

j Operating Reactors Branch No. 1

@1 Division of Licensing Washington, DC 20555 2g F-at

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Reference:

Beaver Valley Power Station, Unit No. 1

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Docket No. 50-334 DCP 451 e

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Centlemen:

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In our letter dated February 23, 1981, we committed to modifying the thin Feedwater Valve circuits to preclude opening of these valves upon reset of the Safety Injection Signal.

During review of the proposed design change, our Licensing and Engineering Departments determined that this change was not necessary and consequently request to be relieved of che requirement to modify these circuits.

Our justification is based upon the following inherent design features of the existing system:

t 1.

The Main Feedwater Valves will not automatically reposition upon reset of the SIS signal since a separate and redundant trip on the valves still exists. This signal is developed by a low Tave (less than 554F) coincident with a reactor trip signal (P4). Refer to the attached diagrams which depict this additional trip on the valves and to FSAR Figure 7.2-1 instrumentation and control system fer additional information.

NOTE: The K601 relay contact is dropped out by an SIS signal and the K620 relay contact is operated by either a high-hig a steam generator level or the P4 and 554F logic.

2.

The SlS signal causes a full reactor trip automatically and isolates the main feedwater header by closing: the. containment isolation valves, main and bypass regulating valves, and tripping the Main Feedpumps.

I 3.

A trip of a Main Feedpump also closes its respective discharge valve which is powered from the Emergency 480V Bus.

These valves are in a series arrangement with the Main Feedwater Regulating Valves.

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.i-Beaver Valley Power Station, Unit No. 1 Docket No. 50-334 DCP 451 Page 2 i

4.

The Feedwater Isolation Signal effects isolation of the individual l'

feedwater headers at four points:

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• l.

Closure of the Containment Isolation Valves.

• 2.

Closure of the Main Feedwater Regulating and Bypass Regulating Valves.

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• 3.

Trip of the Main Feed Pumps.

4.

Closure of the Main Feed Pump discharge valve upon tripping of the pump.

1 If you have any questions in this regard, please contact my office.

Very truly yours, O

J.

Carey i

Vice President, Nuclear

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• The Feedwater Isolation Signal is diversified with Train "A" and Train l-

"B" redundancy.

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e Beaver Valley Power Station, Unit No.1 Docket No. 50-334 DCP 451 Page 3 cc:

Mr. D. A. Beckman, Resident Inspector U.S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA' 15077 4

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United States Nuclear Regulatory Conunission Operating Reactors Branch No. 1 Division of I.icensing Washington, DC 20555 i-i l

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