ML19282B829

Forwards Formal Calculation Supporting Previously Submitted Abbreviated Analysis Demonstrating Acceptable Small Break ECCS Results W/O Allowing Credit for Charging Pump Flow,Dtd 790216

ML19282B829
Person / Time
Site:	Calvert Cliffs
Issue date:	03/13/1979
From:	Lundvall A BALTIMORE GAS & ELECTRIC CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 7903160237
Download: ML19282B829 (15)

Text

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BALT;MORE GAS AN D ELECTRIC COM PANY GAS AN D ELCCTRIC DUILDING D ALTI M O R E, M ARYL A N D 212 03 March 13, 1979 ARTH UR E. LUN OVA LL,JR.

Vic t Amt sio E = f ss-s Office of tiuclear Reactor Eeculation U. S. !iuclear Regulatory Cc= mission Washington, D. C. 20555 Attn: Mr. Robert W. Reid, Chief Operating Reactors Branch #h Division of Operating Reactors Subj ect: Calvert Cliffs Iluelear Pover Plant Units !!cs. 1 L 2, Docket !ios. 50-317 & 50-318 ECCG Smil Ereak LOCA Analysis

Reference:

EGLE letter dated 2/16/79 frcm Mr. A. E. Lundvall, Jr.

to Mr. R. W. Reid, same subject.

Centlemen:

The referenced letter sub?.itted an abbreviated er.alysis demonstrating acceptable small break ECCS results without taking credit for charging pump flov. Enclosure (1) provides a formal calculation performed by Ccnbustion Engineering which confirms those acceptable results.

Very truly yours, (M ,O  % .

%IC%/  %

cc - J. A. Biddison, Esquire G. F. Trowbridge, Esquire Me s sr s . E. L. Conner , Jr . - IIRC P. W. Kruse - CE (letter only) 7903160237

, .- ENCLOSURE (1) 1.0 Introduction and Summary The small break LOCA ECCS performance for Calvert Cliffs Units 1 and 2 presented herein demonstrates appropriate confomance with 10CFR50.46 which presents the Acceptance Criteria for Emergency Core Cooling Systems for Light Water Cooled Reactors (I) . This evaluation demonstrates acceptable ECCS perfomance for Calvert Cliffs Units 1 and 2 at a peak linear heat generation rate (PLHGR) of 16.0 kw/ft and a reactor power level of 2754 Mwt (102% of 2700 Mwt). The method of analysis and results are presented in the following section. In this analysis, it was conservatively assumed that no injection flow is available from the charging pumps.

2.0 Method of Analysis Reference 3 presents the Calvert Cliffs small break LOCA ECCS perfomance at a reactor power level of 2611 Mwt (1.02% of 2560 Mwt) and a PLHGR of 15.8 kw/ft. In reference 3, the 0.1 ft 2cold leg break in the pump discharge was identified as the worst small break with a calculated peak clad temperature of 1855 F and a peak local clad oxidation percentage of 4.1%. The evaluation presented herein pertains to a re-analysis of the perfomance for the 0.1 ft2 break at a reactor power level of 2754 Mwt and a PLHGR of 16.0 kw/ft.

The evaluation was performed using Combustion Engineering's Small Break Evaluation Model which is described in References 2 and 3.

The evaluation of the small break LOCA perfomance invcived the use of the following computer codes. Blowdown hydraulics are calculated using the CEFLASH-4AS(4) code. Fuel rod temperatures and clad oxidation percentages are calculated using the STRIKIN-II(5) and PARCH (6) codes.

Details of the interfacing of these codes are discussed in Reference 2.

3.0 Results 2

The analysis of the 0.1 ft small break at 2754 Mwt and a PLHGR of 16.0 kw/ft resulted in a peak clad temperature and peak zirconium oxidation percentage of 1940 F and 7.96 %, respectively. The analysis confirms the preliminary evaluation presented in Reference 7, which demonstrated the

peak clad temperature would be less than 1975UF and peak zirconium oxidation would be less than 11.0% at the reactor power level of 2754 Mwt and a PLHGR of 16.0 kw/ft.

The transient values of parameters which most directly affect fuel rod performance are shown in Figure 1 (A through H). The following F.arameters are graphically presented:

(A) Normalized Total Core Power (B) Inner Vessel Pressure (C) Break Flow Rate (D) Inner Vessel Inlet Flow Rate (E) Inner Vessel Two-Phase Mixture Volume (F) Hot Spot Heat Transfer Coefficient (G) Channel Coolant Temperature at Hot Spot (H) Hot Spot Clad Surface Temperature The times at which significant events in the performance of the ECCS and a summary of the hot rod fuel performance are provided in Table 2.

This analysis also demonstrates that the peak clad temperature for the worst small break at 2754 Mwt is much less than that for the limiting large break. Consequently, the limiting break for Units 1 and 2 remains the 0.8 double ended slot break in the cold leg at the pump discharge reported in Reference 8, in which the peak clad temperature was calculated to be 2123 F with the peak local clad oxidation percentage of 15.53% at the PLHGR of 15.5 kw/ft. .

4.0 Conclusion A reanalysis of the ECCS perfomance for the worst small break LOCA for Calvert Cliffs at a reactor power level of 2754 t'wt and a PLHGR of 16.0 kw/ft has been performed. The analysis demonstrated a peak clad temperature of 1940 F and a peak local clad oxidation percentage of 7.96%

thereby demonstrating appreciable margin relative to the Acceptance CriteriaII) for the worst small break LOCA. It can therefore be concluded that operation of Calvert Cliffs Units 1 and 2 at the reactor power level of 2754 Mwt is acceptable. .

5.0 References

.l. Acceptance Criteria for Emergency Core Cooling Systems for Light-Water Cooled Reactors, Federal Register, Vol. 39, No. 3 -

Friday, January 4,1974.

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

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

4. CENPD-133, Supplement 1. "CEFLASH-4AS, A Computer Program for Reactor Blowdown Analysis of Small Break Loss-of-Coolant Accident",

August, 1974 (Proprietary).

CENPD-133, Supplement 3, "CEFLASH-4AS, A Computer Program for Reactor Blowdown Analysis of the Small Break Loss-of-Coolant Accident", January 1977 (Proprietary).

5. CENPD-135, "STRIKIN-II, A Cylindrical Geometry Fuel Rod Heat Transfer Program", April,1974 (Proprietary).

CENPD-135, Supplement 2-P, "STRIKIN-II A Cylindrical Geonetry Fuel Rod Heat Transfer Program (Modification)", February,1975 (Proprietary).

CENPD-135, Supplement 4-P, "STRIKIN-II, A Cylindrical Geometry Fuel Rod Heat Transfer Program", August,1976 (Proprietary).

CENPD-135, Supplement 5-P, "STRIKIN-II, A Cylindrical Geometry Fuel Rod Heat Transfer Program", April,1977 (Proprietary).

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

CENPD-138, Supplement 1, " PARCH, A FORTRAN-IV Digital Program to Evaluate Pool Boiling, Axial Rod and Coolant Heatup" (Modification),

February 1975 (Proprietary).

CENPD-138, Supplement 2, " PARCH, A FORTRAN-IV Digital Program to Evaluate Pool Boiling, Axial Rod and Coolant Heatup" (Modification),

January 1977 (Proprietary).

7. Letter from BG&E to the NRC transmitting Calvert Cliffs Units l&2 Small Break ECCS Expected Performance at 2754 Mwt.

8. Letter from BG&E to the NRC transmitting the Calvert Cliffs Unit 2, Cycle 2, ECCS Analysis.

Table 1 ,

General System Parameters Calvert Cliffs ,

Quanti ty .

Value Reactorpowerlevel(102%offlominal) 2754 !!Wt Averagelinearheatrate(102%of.flominal) 6.5205 kw/ft Peak linear heat rate 16.0 kw/ft Gap conductance at peak linear heat rate 1882 . BTU /hr-ft OF Fuel centerline temperature at peak linear heat rate 3755. F Fuel average temperature at peak linear heat rate 2286.UF Hot rod gas pressure 1026 psia Moderator temperature coefficient at initial density 0.3x10~4 4/ F 0

System flow rate (total) 139.1x10 1um,%

Core flow rate 135,3x10 6 lbm/hr Inner vessel initial pressure 2250 psia Reactor vessel inlet temperature 550 F Reactor vessel outlet temperature 601 F Active core height 11. 39 f t Fuel rod OD 0.44 in Number of cold legs .;

Number of hot legs 2 Cold leg diameter . 30 in Hot leg diameter 42 in Low pressurizer pressure scram setpoint 1728 psia

. Safety injection actuation signal setpoint 1578 psia Safety injection tank pressure 215 psia High pressure safety injection pump shutoff head 1225 psia Low pressure safety injection pump shutoff head 209 psia HPSI pump flow delivered to reactor vessel 0.75 pump LPSI pump flow delivered to reactor vessel 0.5 pump Safety injection tank flow delivered to reactor vessel 3 9

9

Table 2 Times of Interest and Fuel Rod Performance Summary for 0.1 f t 2 Break Time for HPSI pump on 58 sec Time for LPSI pump and SI tanks on a Time for SI H2 O level to reach bottom of fuel b Hot spot peak clad temperature occurs 1584 sec Maximum clad surface temperature 1940 F Elevation of hot spot (from bottom of core) 9.7 Ft Corewide zirconium oxidation <0. 84%

Peak percent zirconium oxidation 7.96%

a. Calculation terminated before LPSI pump or SI tank actuation

b. Core never totally uncovers

FIGURE 1-A 0'.1FTgALVERTCLIFFSUNITSIAt1DII COLD LEG BREAK AT PUMP DISCHARGE  ;

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FIGURE 1-B

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CALVERT CLIFFS UtilTS 1 Af1D II 0.1 FT2 COLD LEG BREAK AT PUMP DISCHARGE IfillER VESSEL PRESSURE ,

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s 1600 .

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FIGURE 1-D - '

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(SMALL BREAK Af!ALYSIS) .

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FIGURE l-G CALVERT CLIFFS UNITS I AND II 0.1 FT2 COLD LEG BREAK AT PUMP DISCHARGE COOLANT TEMPERATURE AT HOT SPOT ,

(SMALL BREAK ANALYSIS) .

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FIGURE 1-H CALVERT CLIFFS Ui4ITS I Ai'D II 0.1 FT2 COLD LEG BREAK AT PUMP DISCHARGE CLAD SURFACE TEMPERATURE AT HOT SPOT ,

(SMALL BREAK A!!ALYSIS) 2200 1900 ,

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g 1600 -

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w g -

LS 1300 M .

u 1000 / ~

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400 0 500 1000 1500 2000 2500 TIME, SEC e