ML20095E077

Proposed Tech Specs Bases Page B2-2,including GE11 GEXL Correlation Axial Power Profile & R-factor Ranges & Correcting Error in GE11 GEXL Correlation Mass Flux Range in GE Design ref,NEDE-31152-P, GE Fuel Bundle Designs

ML20095E077
Person / Time
Site:	Pilgrim
Issue date:	12/08/1995
From:	BOSTON EDISON CO.
To:
Shared Package
ML20095E076	List: BECO-LTR-95-121, Forwards Revised Bases Page B2-2 to 950714 Proposed TS Change to Section 2.1 Bases,Safety Limits,Section 3.3.C, Scram Insertion Times & Section 4.11.C,MCPR,including GE11 GEXL Correlation Axial Power Profile & R-factor Ranges ML20095E077
References
NUDOCS 9512140176
Download: ML20095E077 (1)

Text

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. c BASES:

2.0 SAFETY LIMITS (Cont)

FUEL' CLADDING Since the pressure drop in the bypass region is essentially all j INTEGRITY (2.1.1) elevation head, the core pressure drop at low power and flows will -

(Cont) always be greater than 4.5 psi. Analyses show that with a bundle  ;

flow of 28 x 103 lbs/hr, bundle pressure drop is nearly 1 independent of bundle power and has a value of 3.5 psi. Thus, the j bundle flow with a 4.5 psi driving head will be greater than 28 x 108 lbs/hr. Full scale ATLAS test data taken at pressures from 14.7 psia to 800 psia indicate that the fuel assembly critical power at this flow is approximately 3.35 MWt. With the design ,

peaking factors, this corresponds to a THERMAL POWER of more than )

50% of RATED THERMAL POWER. Thus, a THERMAL POWER limit of 25% of l RATED THERHAL POWER for reactor pressure below 785 psig is conservative.

The Safety Limit MCPR is determined using the General Electric Thermal Analysis Basis, GETAB (1), which is a statistical model that combines all of the uncertainties in operating parameters and the procedures used to calculate critical power. The probability  !

of the occurrence of boiling transition is determined using the I

General Electric Critical Quality (X) - Boiling Length (L), GEXL, correlation. l I

The GEXL correlation is valid over the range of conditions used in '

the tests of the data used to develop the correlation. These I

conditions are-Pressure: 800 to 1300 psia Mass Flux: 0.1 to 1.5 M1b/hr-ft2 Inlet Subcooling: 0 to 70 Btu /lb Axial Profile: 1.5 chopped cosine 1.7 inlet peaked 1.7 outlet peaked R-Factor 0.95 to 1.20 Rod Array 9X9 GE 11 array MINIMUM CRITICAL The fuel cladding integrity Safety Limit is set such that no fuel POWER RATIO damage is calculated to occur if the limit is not violated. Since (2.1.2) the parameters which result in fuel damage are not directly observable during reactor operation, the thermal and hydraulic conditions resulting in a departure from nucleate boiling have been used to mark the beginning of the region where fuel damage could occur. Although it is recognized that a departure from nucleate boiling would not result in damage to BWR fuel rods, the critical power at (Cont)

Amendment No. 15;-42;-722-195;-129;-133 B2-2

' 95121401'76 951208 PDR ADOCK 05000293 p PDR

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