ML20115J066

Small Break Loca/Eccs Performance Analysis W/Axial Shape Index of -0.10

ML20115J066
Person / Time
Site:	Millstone
Issue date:	04/30/1985
From:	NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20115J053	List: B11486, Forwards Small Break Loca/Eccs Performance Analysis W/Axial Shape Index of -0.10. Encl Analysis Amends Loca/Eccs Analysis Provided in Per 10CFR50,App K-II.1.b. Previous Reviews Re Effects of Reloads Remain Valid ML20115J066
References
TAC-56814, NUDOCS 8504230361
Download: ML20115J066 (7)

Text

o Docket No. 50-336 Attachment 1 Millstone Nuclear Power Station, Unit No. 2 Small Break LOCA ECCS Performance Analysis with an Axial Shape Index of -0.10 8504230361 850411 April,1985 POR ADOCK 05000336 P PDR

o O

Page 1 of 6 Millstone Nuclear Power Station, Unit No. 2 Small Break LOCA ECCS Performance Analysis with an Axial Shape Index of -0.10 Introduction A small break LOCA ECCS performance analysis was performed for Millstone Unit No. 2 Cycle 3 to demonstrate compliance with the emergency core cooling system acceptance criteria of 10CFR50.46 (Reference 1). The purpose of the analysis was to justify Cycle 3 operation with an axial shape index (ASI) negative limit of -0.10. The analysis method and results are presented below.

Method of Analysis The original Millstone Unit No. 2 Cycle 3 small break analysis (Reference 2),

herein called the reference analysis, used an axial power shape based on a negative ASI limit of -0.08. The present analysis reanalyzed the limiting small break of the reference analysis using an axial shape based on an ASI of -0.10. All other inputs and assumptions of the reference analysis remained unchanged.

The present analysis was performed using the NRC approved CE small break LOCA ECCS evaluation model (Reference 3). The analysis consisted of the calculation of'the cladding temperature for the 0.1 ft.2 cold leg break during the pool boiling portion of the transient. The analysis used the PARCH computer code (Reference 4).

The hydraulic transient calculation of the reference analysis was not reanalyzed.

It conservatively applies to the present analysis since the effect of decreasing the negative limit on ASI in the hydraulic analysis of a small break LOCA is to increase the calculated two-phase mixture level in the core. The forced convection portion of the cladding temperature calculation remains applicable since both the reference analysis and the present analysis were performed at the same peak linear heat rate and the hot rod was predicted to remain in nucleate boiling during that ortion of the transient.

Results Table 1 presents the results of the present analysis of the 0.1 ft.2 break for an axial power shape based on an ASI of -0.10. Figures 1 through 3 present the transient results for cladding temperature, coolant temperature and heat transfer coefficient, respectively, at the location of peak cladding temperature.

The present analysis demonstrates acceptable ECCS performance for the small break LOCA for Millstone Unit No. 2 Cycle 3 for a negative ASI limit of -0.10.

The peak clad temperature was calculated to be 20350F as compared to the acceptance criterion of 22000F. The peak local and core wide cladding oxidation percentages were calculated to be less than 10.4% and less than 0.34%,

respectively, as compared to the acceptance criteria of 17 % and 1 %,

respectively.

T-Page 2 of 6 References

1. Acceptance Criteria for Emergency Core Cooling Systems for Light Water Cooled Nuclear Power Reactors, Federal Register, Vol. 39, No. 3, January 4, 1974.

2. W. G.- Counsit letter to R. Reid, dated March 22,1979.

3. CENPD-137, " Calculative Methods for the CE Small Break LOCA Evaluation Model," August 1974 (CE Proprietary).

CENPD-137, Supplement 1, " Calculative Methods for the CE Small Break LOCA Evaluation Model," January 1977 (CE Proprietary).

4. . CENPD-138, " PARCH, A FORTRAN-IV Digital Program to Evaluate Pool Boiling, Axial Rod and Coolant Heat-up," August 1974 (CE Proprietary).

CENPD-133, Supplement 1, " PARCH, A FORTRAN-IV Digital Program to Evaluate Pool Boiling, Axial Rod and Coolant Heat-up (Modifications),"

February 1975 (CE Proprietary).

CENPD-138, Supplement 2, " PARCH, A FORTRAN-IV Digital Program to Evaluate Pool Bolling, Axial Rod and Coolant Heat-up," 3anuary 1977 (CE Proprietary).

F .i Paam 3 of 6 Table 1 Result of Analysis Parameter Value Break Size / Location 0.1 ftr/RCP discharge leg Peak Linear Heat Rate 16.0 kw/ft Axial Shape Index -0.16 fl)

Peak Cladding Temperature 2035*F Peak Local Cladding Oxidation <10.4% ,

Core Wide Cladding Oxidation <0.34%

Location of Peak Cladding Temperature 10.8 ft (1) Value includes an uncertainty allowance of 0.06 . j O

o Pace 4 of 6 FIGURE 1 MILLSTONE POINT UNIT 2 CYCLE 3 0,1 FT2 RCP DISCHARGE LEG BREAK CLAD TEliPERATURE AT HOT SPOT 2400 -

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i Page 5 of 6

- f!GURE 2 MILLSTONE POINT UNIT 2 CYCLE 3 0.1 FT2 RCP DISCHARGE LEG BREAK COOLANT TEMPERATURE AT HOT SPOT

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7' Page 6 of 6 FIGURE 3 MILLSTONE POINT UNIT 2 CYCLE 3 0.1 FT2 RCP DISCHARGE LEG BREAK HEAT TRANSFER COEFFICIENT AT HOT SPOT t

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