ML20093P171

Responds to Request for Addl Info Re 840619 Application for Amend to Tech Specs,Changing Measurement Uncertainty for RCS Flow Rate & Defined Allowable Power Levels for Flow Rate Less than 100% Thermal Design Flow

ML20093P171
Person / Time
Site:	Summer
Issue date:	10/30/1984
From:	Dixon O SOUTH CAROLINA ELECTRIC & GAS CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 8411060167
Download: ML20093P171 (2)

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P SOUTH CAROLINA ELECTRIC & GAS COMPANY p POST CareCE 764 COLuusiA. South C AmoumA 292t8 O. W Omose. Ja.

October 30, 1984

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Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Virgil C. Summer Nuclear Station Docket No. 50/395 Operating License No. NPF-12 Reactor Coolant System Flow

Dear Mr. Denton:

On June 19, 1984, South Carolina Electric and Gas Company (SCE&G) submitted a request to amend the Technical Specifications for the Virgil C. Summer Nuclear Station.

This request involved changes in the measurement uncertainty for the Reactor Coolant System (RCS) flow rate and defined allowable power levels for an RCS During the flow rate less than 100% of Thermal Design flow.

review of this submittal, the Staf f had several questions about This letter is the proposed Technical Specification changes..

provided in response to those questions.

The first question requested the value for the thermal design flow rate in gallons per minute (GPM) . The design flow rate for the Virgil C. Summer Nuclear Station is 98,000 GPM per loop, or 294,000 GPM total.

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The second question concerns the values calculated for the I digital voltmeter (DvM) elbow tap indication uncertainty for one loop and correspondingly for three loops as stated in Table 4 of f the June 19, 1984 letter. In re-verifying these values, it has been determined that the uncertainties, as listed at theusing The correct uncertainties, bottomthe i

of Table 4, are incorrect.

1 input values and the statistical summation formethod found the total in channel loop Table 4, are i 1.555% as opposed to i 1.535%

uncertainty with 1 tap and 1 0.898% as opposed to 1 0.886% for the total RCS channel uncertainty with 3 loops.

The third question requests confirmation of the value in Table 5 of the July 19, 1984 letter for the total RCS elbow tap channel uncertainty utilizing DVM readings. The correct value for the total RCS elbow tap channel uncertainty utilizing DVM readings is This value has been increased slightly f rom the value i 2.00%.

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Mr. Harold R. Denton, Director Reactor Coolant System Flow October 30, 1984 Page 92 of 11.994 as a resultHowever, of the changes noted in response to the this increase does not change the previous question. As stated in Table 5, total RCS flow measurement uncertainty.

the total RCS uncertainty is i 2.04.

The fourth question addresses the possibility of crud buildup and its associated uncertainty factor. SCE6G is scheduled to perform a modification during the present refueling outage toThis install inspection ports at the feedwater venturi nozzles.

modification will allow for visual inspection and cleaning of the nozzles. These nozzles will be cleaned with a high pressure water spray at each refueling to mitigate crud buildup. It is SCEEG's position that the installation of this modification and the cleaning to be conducted prior to startup of each cycle obviates the need for including additional uncertainty in the total calorimetric uncertainty to account for crud buildup.

In re-examining the July 19, 1984 submittal, an error was discovered on the marked up Technical Specification Figure 3.2-3, "RCS Flow Rate Versus R." The RCS total flowrate for a 984 power level should be 29.69 x 104 GPM as opposed to the 29.67 x 104 GPM indicated on the marked up figure. Flowrates for all other indicated power levels have been reverified and are correctly stated in the July 19, 1984 letter.

If you have any further questions, please advise.

Very trul yours,

~'

, L' j O. W.'Dixo J AMM/OWD/gj cc: V. C. Summer C. A. Price T. C. Nichols, Jr./O. W. Dixon, Jr. C. L. Ligon (NSRC)

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