ML20247P620

Safety Evaluation Supporting Util SAFER/GESTR-LOCA Analysis

ML20247P620
Person / Time
Site:	Brunswick
Issue date:	06/01/1989
From:	Office of Nuclear Reactor Regulation
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ML20247P618	List: ML20247P612 ML20247P620
References
NUDOCS 8906060217
Download: ML20247P620 (4)

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1. $%g . . UNITED STATES

, j ,g NUCLEAR REGULATORY COMMISSION

.E j _WASHINGTON, D. C. 20555

.....f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO SAFER /GESTR-LOCA ANALYSIS CAROLINA POWER & LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 DOCKET NOS. 50-325 AND 50-324

1.0 INTRODUCTION

By letter dated March 29, 1989, as supplemented May 17, 1989, the Carolina-

' Power & Light Company.(CP&L) requested approval to use SAFER /GESTR-LOCA h

application methodology for analysis of postulated loss-of-coolant accidents for the Brunswick Steam Electric Plant, Units 1 and 2 (Brunswick). The methodology was generically accepted for referencing.by the staff in a June 1,1984 letter from C.O. . Thomas (NRC) to J. F. Quick' (GE) entitled, " Acceptance for Referencing of Licensing Topical Report NEDE-237ES, Revision 1 Volume'III (P), 'The GESTR-LOCA and SAFER Models:

for. Evaluation of the Loss-of-Coolant Accident'." CP&L submitted a General Electric prepared document entitled, " Brunswick Steam Electric Plant, Units 1 and 2 SAFER /GESTR-LOCA, Loss-of-Coolant Accident Analysis" (NEDC-31624P), dated September 1988,'as the technical justification for-use of. the methodology at Brunswick. The staff acceptance of the methodology for use at Brunswick will enable CP&L to reference its applicability for future technical specification changes, and will serve as a revision to the BSEP LOCA licensing basis.

2.0 EVALUATION In order to approve the use of the subject methodology at Brunswick, the  !

staff evaluated whether the plant specific methodology is consistent with.. '

and bounded by, the generically approved methodology and whether or not it .  !

is. applied by qualified personnel. Since General Electric performed the analysis on behalf of CP&L, and General Electric is qualified in this ,

' technical area, the staff concludes that qualified personnel performed the i analysis and the only further evaluation that is necessary is to ensure i that the Brunswick plant specific use of the methodology is consistent i with and bounded by the staff generically approved methodology.

The staff has specified the necessary conditions for demonstrating plant .]

specific applicability of the SAFER /GESTR-LOCA methodology. These conditions are:

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).. 1. Calculation of a sufficient number of plant speciffe Peak Cladding Temperature (PCT) points, based on both nominal input values and

. Appendix K values, to verify the shape of the PCT curve versus break size.

2. . Confirmation that plant specific operating parameters have been L bounded by the models and inputs used in the generic calculation.

3. Confirmation that the plant specific Emergency Core Cooling System-o (ECCS) configuration is consistent with the referenced plant class B ECCS configuration.

H CP&L,.through the General Electric prepared analysis (the GE report),

reported the results.of those analyses that are required to meet these conditions.. The analyses addressed both Brunswick units.

L . The ' analyses for Unit 2 includgd break sizes ranging from 'a recirculation dischargelinebreakof0.05ft.totheDesjgnBasisAccident(DBA) recirculation suction line break of 4.26ft . Different break sizes were L analyzed in conjunction with ECCS failure combinations. The cases were' evaluated to establish the trend of PCT curves (nominal and Appendix K)

=versus break size. Fourteen Unit 2 recirculation line break cases were summarized in Table 5-3 of the GE report. The staff concludes for Unit 2 i that a-sufficient number of plant specific PCT points based on both nominal input values and Appendix K values to verify the shape of the PCT curve versus break size were used.

The analysis for Unit 1 included five recirculation line break cases, as i summarized in Table 5-2 of the GE report. Four of these Unit I cases ,

were also analyzed for Unit 2. The staff compared the results of like - '!

cases of both units, and they are similar. If additional cases were analyzed for Unit 1, as was done for Unit 2, the staff would expect similar results.. Thus, the staff concludes for Unit I that a sufficient number of plant specific PCT points based on both nominal input values and  !

Appendix K values to verify the shape of the PCT curve versus break size- l were used.  :

The analysis for. Unit 2 also included five non-recirculation line break cases. The cases were summarized in Table 5-4 of the GE report. The j

. results demonstrate that these postulated non-recirculation line breaks are significantly less limiting than the postulated recirculation line breaks. No cases were presented for Unit I non-recirculation line breaks.

m However, if the Unit I cases were analyzed, the staff would expect results similar to Unit 2. In addition, the staff would expect the Unit 1  !

non-recirculation line breaks to be significantly less limiting than the '

postulated recirculation line breaks. Thus, the staff concludes that .)

condition 1 for non-recirculation line breaks for both units is met. '

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.e The input parameters for both the nominal and Appendix K cases are within p those used in the approved generic analysis. Table 4.1 of the GE report shows the plant operating conditions and the fuel parameters used in the Brunswick LOCA evaluation. Table 4.2 of the GE report identifies the ECCS parameters utilized for each Brunswick unit. The staff concludes that condition 2 is met.

The staff notes that some plant specific input parameters have been increased beyond present analysis of record values and TS values. For example, the Diesel Generator start time was increased from 10 seconds to 15 seconds. The table provided in the May 17, 1989 submittal contains a summary. The GE report concludes that the changes in PCT are significantly small compared to safety margin available, considering the specified ECCS parameters' relaxations. The GE report conclusion appears reasonable and is acceptable.

Lastly, the staff notes that significant system or component assumptions included no offsite power, no high pressure coolant injection system, two SRV/ ADS valves out of service and a SRV setpoint tolerance of 3%. These assumptions are acceptable.

The EECS. configuration used in Brunswick plant specific analysis is bounded by that used in the generic analyses. The generic calculations for the BWR 3/4 plant class used an ECCS configuration typical of that plant type. For a DC power failure, the systems . remaining for the generic BWR 3/4 include one Low Pressure Core Spray (LPCS) system and two Low PressureCoolantInjection(LPCI) systems. The dual unit Brunswick plant has two.potentially limiting DC power failures as shown in Table 4-3 of-the GE report. One failure, termed DC Power (1), results in one LPCS and three LPCI systems remaining. The other failure, termed DC Power (j), has two LPCS and two LPCI systems remaining. For either failure, four ECCS systems remain available, as compared to the those available systems for the generic analysis. Thus, the staff concludes that the Brunswick ECCS configuration is bounded by the generic analysis, and condition 3 is met.

The GE report presented the Brunswick limiting PCT sumary for each unit in Table 5-1. The nominal PCT value, Appendix K PCT value, licensing basis PCT value, and upper bound PCT value for each Brunswick unit was given. All values are well below the 2200*F limit (upper bound PCT less than 1600'F), appear reasonable, meet the staff's acceptance criteria, and are acceptable. Similarly, the peak local oxidation and core wide metal-water reaction values are well below acceptance values of 17% and 1%, respectively, appear reasonable, and are acceptable.

The staff reviewed whether the TS Maximum Average Planar Linear Heat Generation Rate (MAPLHGR) limits are set by the LOCA calculations, or by the thermal-mechanical design calculations. Section 5.4 of the GE report addresses this. The MAPLHGR limits'for the Brunswick LOCA analysis reflect only fuel thermal mechanical constraints and are unaffected by LOCA considerations. This approach is reasonable, and is acceptable.

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3.0 CONCLUSION

1 The staff has reviewed and evaluated the General Electric report, NEDC-31624P, in support of CP&L's request to use SAFER /GESTR LOCA methodology at Brunswick. The staff confirmed plant specific use of the methodology is consistent with and bounded by the staff's generically-approved use of the methodology. The staff concluded that the PCT values, peak local oxidation values, and core wide metal-water reaction values are well below staff acceptance values. Thus, the analyses and results are in accordance with NRC requirements and conformance with the ECCS acceptance criteria of 10 CFR 50.46 and Appendix K has been demonstrated.

On this basis, the analysis contained in the GE report can be used to provide a revised LOCA licensing basis for both Brunswick units, and can be referenced in future licensing submittals.

Principal Contributors: E. Tourigny Dated: June 1, 1989 1

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