ML20116D360

Proposed Tech Spec 15.3.10 Re Basis for Control Rod & Power Distribution Limits

ML20116D360
Person / Time
Site:	Point Beach
Issue date:	10/30/1992
From:	WISCONSIN ELECTRIC POWER CO.
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ML20116D358	List: ML20116D353 ML20116D360
References
NUDOCS 9211050336
Download: ML20116D360 (2)

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anomalies which would, otherwise, aff9ct these bases.

Axial Power Distribution The limits on axial flux difference (AFD) assure that the axial power distribution is maintaintd such that the F,(Z) upper bound envelope of FA'""

times the normalizcd axial peaking factor [K(Z)) is not exceeded during either normal operation or in the event of xenon redistribution following power changes.

This ensures that the power distributions assumed in the large and small break LOCA analyses will bound those that occur during plant operation.

Provisions for monitoring the AFD on an automatic basis are derived from the plant process computar through the AFD monitor alarm. The computer determines the AFD for each of the operable excore channels and provides a computer alarm if the AFD for at least 2 of 4 or 2 of 3 uperable excore channels are outside the AFD limits and the reactor power is greater than 50 percent of Rated Power.

9211050336 9D1070 PDR ADOCK 05000266 P

PDR SER 92-070 15.3.10-12 October 30, 1992

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b An upper bound envelope of 2.50 times the normalized peaking factor axial l

depenoence of Figure 15.3.10-3 consistent with the Technical Specifications on power distribution control as given in Section 15.3.10 eas used in the large

.and small break LOCA analyses.

The envelope was determined based on allowable power dentity distributions at full power restricted to axial flux difference.

(41) values consistent with those in Specification 15.3.10.B.2.

The results of the analyses based on this upper bound envelope indicate a peak clad temperature of less than the 2200'F limit. When an F measurement is taken, both e gerimental g

error and manufacturing tolerance must ce allowed for.

Five percent is the

)

appropriato allowance for a full core map +aken '. tith the seveable incere detector 1

flux mapping system and three percent is the appropriate allowance for manufac-turing tolerance.

InthedesignilmitofFfg.thereiseightpercentallowance for uncertainties which means that normal operatit.n of the core is expected to result in a design F H $ 1.70/1.08.

The logic behind the larger uncertainty in l

this case is that (a) normal perturbations in the radial power shape (i.e., rod misalignment) affect F g, in most cases without necessarily affecting F, (b) g while the operator has a direct influence on F through movement of rods, and g

canlimitittotheoesiredvalue,hehasnodirectcontroloverFfg and(c)an g

error in the predictions for radial power shape which may be detected owing startup physics tests can be compensated for in F by tighter axial control; but g

compensathn for F is less readily available. When a measurement of Ffg is H

taken, experimental error must be allowed for and four percent is the appropriate allowance for a full core c.ap taken with the moveable incore detector flux mapping system.

Nessuren,ents of the iwt t.hannel factors are required as part of startup physics tests, at least each full pewer month operation, and whenever abnormal power distribution conditions require a reduction of core power to a level based upon measured hot channel factors. The incore map taken following initial loading provides confirmation of the basic nuclear. design bases including proper fuel loading patterns. The periodic monthly incore mapping provides additional assurance that the nuclear design bases remain inviolate and identify operational Unit 1 - Amendment No.120 15.3.10-11 May 8, 1989 Unit 2 - Amendment No. 123 November 1, 1989

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