ML20070W051

Responds to 830103 Request for Addl Info Re Boron Concentration Reduction in Boron Injection Tank Per Util .Existing Emergency Operating Procedure for Small Break LOCA Not Impacted by Proposed Change in Concentration

ML20070W051
Person / Time
Site:	Farley
Issue date:	02/11/1983
From:	Clayton F ALABAMA POWER CO.
To:	Varga S Office of Nuclear Reactor Regulation
References
TAC-49234, TAC-49323, NUDOCS 8302180247
Download: ML20070W051 (11)

Text

Mailing Address Alabama Pow;r Comp:ny

• 600 North 18th Street Post Offica Box 2641 Birmingham, Alabama 35291 Telephone 205 783-6081 F. L Clayton, Jr.

R$$';2fg"' AlabamaPbwer the southem electic system February 11, 1983 Docket Nos. 50-348 50-364 Director, Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Mr. S. A. Varga Joseph M. Farley Nuclear Plant - Units 1 and 2 Boron Concentration Reduction in the Boron Injection Tank Gentlemen:

On January 3, 1983, Messrs. E. A. Reeves and R. Barrett of the NRC verbally requested some additional information and clarification regarding boron concentration reduction in-the boron injection tanks (BIT) at the Farley Nuclear Plant as proposed in the Alabama Power Company letter of December 30, 1982. A restatement of the NRC requests and the Alabama Power Company responses are as follows:

1. Request Explain why the variation of Keff with core temperature is shown to be less severe in the December 30, 1982 submittal (Figure III.A-1) compared to the assumption used in the original FSAR analysis (Figure 15.2-40).

Response

The difference in the figures is due to the use of different computer codes. The original FSAR curve (Figure 15.2-40) was the result of the MAPVEL code while the December 30, 1982 submittal curve (Figure III. A-1) was the result of the LOFTRAN code. The same initial conditions were used in both codes such that the difference reflects / 1 actual improvements in analytical techniques. The LOFTRAN f;(>b I analysis is verified to be conservative by checking the reactivity and power results at the limiting conditions as discussed in Section III.B.1 of the December 30, 1982 submittal.

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e Mr. S. A. Varga February 11, 1983 Nuclear Reactor Regulation Page 2 U.S. Nuclear Regulatory Commission

2. Request Explain why the December 30, 1982 submittal assumes an initial core average temperature of approximately 550 F (Figure III.A-13) compared to the assumption used in the FSAR of approximately 580 F (Table 15.4-22).

Response

The actual value used for the initial core average temperature was 547"F for both the December 30, 1982 submittal and the FSAR. The value in FSAR Table 15.4-22 was mistakenly listed as 574 F (a typographical error).

This error will be corrected in the annual FSAR update.

FSAR Figures 15.4-29 and 15.4-30 show the correct initial core average t_mperature of 547 F. Therefore, the December 30, 1982 submittal assumption is consistent with the original FSAR assumption.

3. Rf quest P ovide a copy of the DNBR curve for the Dacember 30, 1982 submittal analysis results.

Response

A DNBR curve was not generated as a product of the analysis effort. The evaluation of the DNBR was done on a state-point basis. The DNBR was not calculated during the transient calculations, nor was it calculated using the LOFTRAN code. Based on previous results, the minimum DNBR has been found to occur near the point of maximum return to power, therefore only a few state-points were evaluated in the range of the peak heat flux. The state-points evaluated show the same general trend as the plot of DNBR versus time in WCAP-9226, the steamline break topical report. As shown in the topical, only for a small power range does the DNBR approach a minimum value. For all other power levels the DNBR is much greater than 1.3.

Therefore, an evaluation of a larger number of state-points is not necessary and the evaluation presented in the December 30, 1982 submittal should be sufficient to demonstrate that the DNBR remains above the design criterion.

4. Request Document the impact of the boron concentration reduction in the BIT on the plant operating procedures for a small break LOCA.

Mr. S. A. Varga February 11, 1983 Nuclear Reactor Regulation Page 3 U.S. Nuclear Regulatory Commission

Response

The existing Farley Nuclear Plant procedures covering action associated with a small break LOCA do not assume credit for the boron injection from the BIT. The procedure requires that operator action be taken, as necessary, to achieve a boron concentration sufficient for safe shutdown. This is accomplished by adjusting the volume control tank blended flow from the boric acid tank (BAT) for the safe shutdown boron concentration. This action remains the same whether the BIT boron concentration is 20,000 ppm or 0 ppm. Therefore, the existing emergency operating procedure covering action associated with a small break LOCA is not impacted by the proposed change in the BIT boron concentration.

If there are any additional questions or requests for clarification, please advise.

Yours very tru ,

Y dW' F. L. Clayton, Jr. i FLCJr/GGY:jc-D34 cc: Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. J. P. O'Reilly Mr. E. A. Reeves Mr. W. H. Bradford l

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