ML19274D153

Requests Formal Approval of Encl Final Diagram & Mod Re Replacement of Flow Restricting Orifices W/Manual Globe Throttling Valves

ML19274D153
Person / Time
Site:	Arkansas Nuclear
Issue date:	01/03/1979
From:	David Williams ARKANSAS POWER & LIGHT CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
1-019-1, 1-19-1, NUDOCS 7901150105
Download: ML19274D153 (3)

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ARKANSAS POWER & LIGHT COMPANY POST OFFICE BOX 551 UTTLE ROCK. ARKANSAS 72203 (501) 371-4000 January 3, 1979 1-019-1 Director of Nuclear Reactor Regulation Attn: Mr. R. W. Reid, Chief Operating Reactor Branch #4 U. S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Arkansas Nuclear One-Unit 1 Docket No. 50-313 License No. DPR-51 ECCS Small Break A Long-Term Modification -

(File: 1510)

Gentlemen:

Our letter of October 27, 1978, provided you with a conceptual design of our proposed ECCS Small Break Long-Term Modification. Subsequent to that letter,. we discussed with the staff (telecon December 1, 1978, between G. Vissing, et a l .. , and Ted Enos) replacing the flow restricting ,

orifices with manual globe throttling valves. The staff agreed with the use of the globe valves.

The staff stated that the design appeared sound but a flow test to verify the required 70/30 flow split would be necessary. We verbally committed to performing a flow test in a December 2, 1978 telecon between G. Vissing and Ted Enos.

While completing final engineering on this modification, certain minor modifications'became necessary. A diagram of the final design is attached.

The globe (throttling) valves were chosen, as opposed to flow orifices as the throttling capability provides for better

" fine tuning" of the system. These valves will be locked in the correct position.

790115 N 6 ME.MBEA MiOOLE GOUTH UTILIT:ES SYSTEM

- Page.2

. January 3, 1979 Four inch cross connect piping will be used instead of three inch as it results in a reduced head loss.

The gate valves added in piping sections 8-10 and 9-11 are to be installed for isolation of the check valves for ASME Section XI testing and will normally be locked open.

The flow orifices in piping sections 4-6 and 5-7 are to be installed to preclude pump runout and to assist the throttling valves. The orifices in piping sectivns 6-9 and 7-11 are to be installed to equalize head loss in the injection legs as two of the legs are longer than the other two and have more head loss associated with them.

Equalizing the head loss in the four legs will help achieve a 70/30 flow split. -

We understand that this modification is acceptable to the staff". However, we request your formal approval as soon as possible as work is scheduled to begin almost immediately.

Very truly yours,

/ -]v W- -

Daniel H. Williams Manager, Licensing DHW/dt Attachments 9

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