ML17340B225

Nonproprietary Version of Safety Evaluation Supporting Proposed Tech Specs Changes Re Radial Burndown & Base Load Operation

ML17340B225
Person / Time
Site:	Turkey Point
Issue date:	05/14/1981
From:	Robert E. Uhrig FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17340B223	List: ML17340B222 ML17340B224 ML17340B225
References
NUDOCS 8105210116
Download: ML17340B225 (10)

Text

SAFETY EVALUATION Re: Turkey Point Units 3 & 4 Docket No. 50-250 and 50-251 Radial Buzndown and Base Load 0 eration I. Introduction The present Technical Specifications provide for axial power distribution controls, which are given in terms of flux difference limitations and control bank inser-tion limits. These controls are designed to minimize the effects of xenon redistribution on the axial during load-follow maneuvers by limiting power'istribution the power to a turnon power fraction, P . This turnon power fraction depends on the analytically predicted maximum [F }, generated by determining F (Z) for a series of load follow maneuvers consistent with axial offset control to a +58 band about the target flux difference.

This safety evaluation supports two alternative methods for determining an increase in the turnon power fraction to a redefined. maximum relative power. The first method, Radial Buzndown operation, is based upon utilizing a measured F<Y(Z) from a full core flux map in conjunction with the analytically determined F (Z). The F (Z) cal-culated by this method, with the appropriate uncertain-ties applied, is used to determine a maximum relative power, P~. The second method, Base Load operation, takes credit for the fact that, the severity of the shapes which need to be analyzed is significantly reduced relative to load follow operation. The F (Z) determined by this method also utilizes a full core flux map in the deter-mination of a maximum relative power, PBL.

II. Evaluation Radial Burndown 0 eration A multi-case elevation-dependent peaking factor analysis (approved by the NRC in Reference 1) or a several case subset analysis is performed to determine the turnon power fraction PT.

Before the relative power is permitted to increase the above P , the maximum relative power permitted under Radial Burndown operation, P~, is deter-mined from a full core flux map and the function FZ(Z) as defined below.

(a,c)

The above description constitutes a straightforward application of previously developed and approved Westinghouse methodology (Reference 2). The con-servative definition of F Z (Z) coupled with the re-quirements of the Radial Burndown Technical Specifi-cation ensures that [F (Z)] Meas conservatively bounds the power distributions that can occur under Radial Burndown operation.

2. Base Load 0 eration Similarly, as in the case of Radial Burndown opera-tion, the relative power is permitted to increase above PT if the following conditions are satisfied.

The indicated flux difference must be held to +2 or

+3%BI about the target axial offset and relative power must be between PT and PT/1.05 for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

The maximum relative power permitted under Base Load operation, PBL is then determined from a full core flux map and the function W(Z) as defined below.

Therefore, as a minimum, power swings between PT/1.05 and P must be considered in generating the function W(Z). For conservatism, power swings between [-

]

(a,' c) Table 1 provides a des-cription of the several cases used to generate W(Z).

Daily load follow is not permitted; however, to allow for some rod sha owi g the 85% EOL cases are based upon a [

is defined as:

] 'epletion. The function W(Z)

,c)

The above description constitutes a straightforward

application of previously developed and approved (W) methodology (Reference 2) to a tightly constrained operating regime. The conservative definition of W(Z) coupled with the restrictions required by Base Load Technical Specification ensures that [F (Z))+ conservatively bounds 0 .BL the power distributions that can occur under Base Load operation.

Reference 1: Vassallo to Eicheldinger letter 4/76.

Reference 2: NCAP-8385

lli. Conclusion Based on the considerations described above, (1) the proposed change does not increase the probability or consequences of accidents or malfunctions of equip-ment important to safety and does not reduce the margin of safety as defined in the basis for any technical specification, therefore, the change does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by opera-tion in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

TABLE 1

[ ) CASES 'EFINING BASE LOAD OPERATION (a,c)

STATE OF FLORlDA )

) ss.

COUNTY OF DADE )

Robert E. Uhrig, being first duly sworn, deposes and says:

That he is a Vice President of Florida Power 6 Light Company, the Licensee herein; That he has executed the foregoing document; that the state-ments made in this. said document are true and correct to the best of his knowledge, information, and belief, and that he is authorized to execute the document on behalf of said Licensee.

Robert, E. Uhrig Subscribed and sworn to before me this day or 19 g/

NOTARY PUBLXC, Florida i and for the county of Dade, State of Notary Put:iic, State of Florida at t.arge

'y My Commission Expires October 30, 1983 COmmiSSiOn eXpireS:~fMdf~~M~aard

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