ML021340157

10CFR50.46 30-Day Report for Changes to Emergency Core Cooling System Performance Analysis

ML021340157
Person / Time
Site:	Calvert Cliffs
Issue date:	05/09/2002
From:	Cruse C Constellation Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC MB2540, TAC MB2541
Download: ML021340157 (10)

Text

Charles H. Cruse 1650 Calvert Cliffs Parkway Vice President Lusby, Maryland 20657 Nuclear Energy 410 495-4455 0

Constellation Nuclear Calvert Cliffs Nuclear Power Plant A Member of the Constellation Energy Group May 9, 2002 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:

Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit Nos. 1 & 2; Docket Nos. 50-3 17 & 50-3 18 10 CFR 50.46 30-Day Report for Changes to the Calvert Cliffs Nuclear Power Plant Emergency Core Cooling System Performance Analysis

REFERENCES:

(a)

CENPD-132, Supplement 4-P-A, "Calculative Methods for the CE Nuclear Power Large Break LOCA Evaluation Model," March 2001 (b)

CENPD-137, Supplement 2-P-A, "Calculative Methods for the ABB CE Small Break LOCA Evaluation Model," April 1998 (c)

Letter from Mr. C. H. Cruse (CCNPP) to NRC Document Control Desk, dated July 27, 2001, "License Amendment Request:

Incorporate Methodology References for the Implementation of ZIRLOTM Clad Fuel Rods into the Technical Specifications" (d)

CENPD-404-P-A, Revision 0, "Implementation of ZIRLOTM Cladding Material in CE Nuclear Power Fuel Assembly Designs," November 2001 (e)

Letter from Ms. D. Skay (NRC) to Mr. C. H. Cruse (CCNPP), dated April 8, 2002, "Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 Amendment Re: Implementation of ZIRLO Clad Fuel Rods (TAC Nos.

MB2540 and MB2541)"

This letter is submitted pursuant to 10 CFR 50.46(a)(3)(ii) to provide notification of a significant change to the peak cladding temperature of the large break loss-of-coolant accident (LBLOCA) and small break loss-of-coolant accident (SBLOCA) analyses for Calvert Cliffs Nuclear Power Plant (CCNPP).

The analyses for the LBLOCA and SBLOCA Emergency Core Cooling System performance has been re-analyzed for the upcoming Unit 1 cycle (Cycle 16). The re-analyses were performed using the newest Nuclear Regulatory Commission (NRC)-accepted versions of the Westinghouse evaluation models for Combustion Engineering designed pressurized water reactors (References a and b). In addition, the new analyses explicitly model the replacement steam generators, which were installed prior to the startup of

Document Control Desk May 9, 2002 Page 2 Cycle 16, and the new fuel design being introduced in Cycle 16. The new fuel design implements ZIRLOTM cladding and mixing vane grids.

Calvert Cliffs Nuclear Power Plant requested an amendment to the CCNPP Unit 1 and Unit 2 operating license (Reference c) to add the methodology references for the new LBLOCA and SBLOCA evaluation models and for ZIRLOTM cladding (Reference d) to the list of approved core operating limits analytical methods in the Technical Specifications. The NRC approved this request on April 8, 2002 (Reference e).

The results of the new analyses and their compliance with 10 CFR 50.46 are summarized in Attachment (1).

As described in the attachment, the new LBLOCA and SBLOCA analyses constitute new licensing basis analyses (analyses-of-record) for Unit 1. A description of the analyses will be incorporated into a future revision of the CCNPP Updated Final Safety Analysis Report.

The results of the new LBLOCA and SBLOCA analyses conform to the Emergency Core Cooling System acceptance criteria of 10 CFR 50.46(b). Because the sum of the absolute magnitudes of the effects on peak cladding temperature due to the changes is greater than 50'F, the changes qualify as being significant as defined in 10 CFR 50.46(a)(3)(i). Consequently, the changes are being reported in this 30-day report. The new analyses will become the licensing basis analyses for Unit 1 upon startup of Cycle 16, which is currently scheduled for late May 2002. The new analyses will become the licensing basis analysis for Unit 2 upon startup of Cycle 15, which is currently scheduled for early May 2003.

Should you have questions regarding this matter, we will be pleased to discuss them with you.

Very truly yours, CHC/DJM/bjd

Attachment:

(1) 10 CFR 50.46 Thirty-Day Report for Changes to the Calvert Cliffs Nuclear Power Plant ECCS Performance Analysis cc:

R. S. Fleishman, Esquire H. J. Miller, NRC J. E. Silberg, Esquire Resident Inspector, NRC Director, Project Directorate I-1, NRC R. I. McLean, DNR D. M. Skay, NRC

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS Calvert Cliffs Nuclear Power Plant, Inc.

May 9, 2002

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS INTRODUCTION This 30-day report is provided for Calvert Cliffs Nuclear Power Plant (CCNPP) in accordance with the requirements of 10 CFR 50.46(a)(3)(ii) for reporting (1) changes in an acceptable evaluation model or the application of such a model and (2) the estimated effect of the changes on the limiting Emergency Core Cooling System (ECCS) analysis. Because the effect on the peak cladding temperature (PCT) of the changes described herein is greater than 50'F, the changes qualify as significant as defined in 10 CFR 50.46(a)(3)(i) and, consequently, are provided in this 30-day report. No errors are reported in this 30-day report.

Emergency Core Cooling System performance for both the large break loss-of-coolant accident (LBLOCA) and the small break loss-of-coolant accident (SBLOCA) have been re-analyzed for CCNPP Unit 1. The analyses were performed with the newest Nuclear Regulatory Commission (NRC)-accepted versions of the Westinghouse Appendix K evaluation models for Combustion Engineering designed pressurized water reactors (PWRs). In addition, the analyses explicitly modeled the replacement steam generators, which were installed prior to the startup of Cycle 16, and the new fuel design that is being introduced in Cycle 16. The new fuel design implements ZIRLOTM cladding and mixing vane grids.

The new LBLOCA and SBLOCA analyses are not assessments (i.e., they do not provide an estimate of the effect of the changes on the limiting ECCS analysis). Rather, they are complete re-analyses that use acceptable evaluation models that are applicable to CCNPP Unit 1. A summary description of the new analyses and their compliance with 10 CFR 50.46 are provided below.

LBLOCA ECCS PERFORMANCE ANALYSIS LBLOCA Evaluation Model The new LBLOCA ECCS performance analysis was performed with the 1999 Evaluation Model (EM) version of the Westinghouse LBLOCA evaluation model for Combustion Engineering designed PWRs (Reference 1). Additionally, the analysis used the ZIRLOTM cladding models described in Reference 2.

The 1999 EM and the ZIRLOTM cladding topical reports were generically accepted by the NRC in References 3 and 4 for licensing applications for Combustion Engineering designed PWRs.

The 1999 EM and the ZIRLOTM cladding topical reports are listed in Technical Specification 5.6.5.b of the CCNPP Technical Specifications as approved analytical methodologies that can be used to determine core operating limits in the Core Operating Limits Report. The license amendment request to add these methodologies to the Technical Specifications was submitted to the NRC in Reference 5 and was accepted by the NRC in Reference 6.

The analysis complies with the limitations/constraints imposed by the Safety Evaluation Reports (SERs) for the 1999 EM and the ZIRLOTM cladding topical reports as well as the applicable limitations/

constraints imposed by the SERs for earlier versions of the LBLOCA evaluation model.

The current CCNPP Unit 1 LBLOCA analysis uses the 1985 EM version of the Westinghouse LBLOCA evaluation model for Combustion Engineering designed PWRs (Reference 7).

Replacement Steam Generators Prior to the startup of Cycle 16, the CCNPP Unit 1 Original Steam Generators (OSGs) were replaced with Replacement Steam Generators (RSGs) that were manufactured by Babcock & Wilcox Canada. The 1

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS RSGs were designed to closely resemble the OSGs and were installed under the provisions of 10 CFR 50.59.

The new LBLOCA analysis explicitly models the RSGs. The analysis accounts for up to 10% tube plugging in each steam generator. In contrast, the current analysis, which models the OSGs, accounts for up to 2500 plugged tubes (approximately 30% tube plugging) per steam generator.

The new LBLOCA analysis also models the increase in minimum Reactor Coolant System (RCS) flow rate that resulted from the installation of the RSGs. Specifically, the analysis uses a minimum RCS flow rate of 370,000 gpm in contrast to 340,000 gpm used in the current analysis.

Fuel Design Changes The Batch V fuel assemblies being introduced in Cycle 16 use mixing vane grids (Turbo fuel assembly) and ZIRLOTM cladding. The new LBLOCA analysis explicitly analyzed the various fuel designs present in Cycle 16 in order to ensure that limiting fuel rod conditions were selected for the break spectrum analysis.

The hot rod heatup portion of the break spectrum analysis, which is performed with the STRIKIN-II computer code, analyzed a ZIRLOTM clad erbia rod in a Turbo fuel assembly. It used reflood heat transfer coefficients that were conservatively biased in order to bound the results of the more limiting fuel types present in Cycle 16, that will not be present in future cycles, and to bound the impact on PCT due to the mixed core effect of co-resident Turbo and non-Turbo fuel assemblies in Cycle 16.

Other Plant Parameter Changes In addition to the changes described above, the new LBLOCA analysis introduced several other changes to plant parameters used in the analysis. The most notable change was an increase in the Peak Linear Heat Generation Rate (PLHGR) from 13.9 kW/ft to 14.3 kW/ft.

The PLHGR was reduced from 14.3 kW/ft to 13.9 kW/ft during Cycle 15 in order to avoid the adverse impact on PCT that resulted from inconsistencies in the timing of cladding rupture calculated by CEFLASH-4A and STRIKIN-II at the higher PLHGR. The improvement made to the CEFLASH-4A fuel rod internal pressure model in the 1999 EM eliminated the inconsistency in the new LBLOCA analysis.

The new LBLOCA analysis also incorporated new bounding values for several physics parameters in order to bound larger cycle-to-cycle variations in the values of the parameters.

Results and Conclusion of the New LBLOCA Analysis Table 1 compares important inputs used in the current and the new LBLOCA analyses. Table 2 compares important results from the two analyses. A more detailed description of the new analysis, including tables and figures that present the results of the break spectrum analysis, will be incorporated into a future revision of the CCNPP Updated Final Safety Analysis Report.

2

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS As summarized below, the results of the new LBLOCA analysis conforms to the acceptance criteria of 10 CFR 50.46(b).

Parameter Criterion Result Peak Cladding Temperature

<22000 F 2026OF Maximum Cladding Oxidation

• 17 %

8.58 %

Maximum Core-Wide Oxidation

• 1 %

<0.99 %

Coolable Geometry Yes Yes The new LBLOCA analysis uses the 1999 EM, which is accepted by the NRC for licensing applications for Combustion Engineering designed PWRs such as CCNPP.

The analysis complies with the limitations/constraints imposed by all applicable SERs. The analysis uses values for plant design data that are either applicable to or bound the configuration of Unit 1 Cycle 16. Calvert Cliffs Nuclear Power Plant, Inc. and Westinghouse have ongoing processes that ensure that the as-operated plant values for PCT-sensitive parameters remain bounded by the values used in the analysis.

SBLOCA ECCS PERFORMANCE ANALYSIS SBLOCA Evaluation Model The new SBLOCA ECCS performance analysis was performed with the S2M (Supplement 2 to CENPD-137 Evaluation Model) version of the Westinghouse SBLOCA evaluation model for Combustion Engineering designed PWRs (Reference 8).

Additionally, the analysis used the ZIRLOTM cladding models described in Reference 2. The S2M and the ZIRLOTM cladding topical reports were generically accepted by the NRC in References 4 and 9 for licensing applications for Combustion Engineering designed PWRs.

The S2M and the ZIRLOTM cladding topical reports are listed in Technical Specification 5.6.5.b of the CCNPP Technical Specifications as approved analytical methodologies that can be used to determine core operating limits in the Core Operating Limits Report. The license amendment request to add these methodologies to the Technical Specifications was submitted to the NRC in Reference 5 and was accepted by the NRC in Reference 6.

The analysis complies with the limitations/constraints imposed by the SERs for the S2M and the ZIRLOTM cladding topical reports as well as the applicable limitations/constraints imposed by the SERs for earlier versions of the SBLOCA evaluation model.

The current CCNPP Unit 1 SBLOCA analysis uses the S1M (Supplement 1 to CENPD-137 Evaluation Model) version of the Westinghouse LBLOCA evaluation model for Combustion Engineering designed PWRs (Reference 10).

Replacement Steam Generators Like the new LBLOCA analysis, the new SBLOCA analysis explicitly models the RSGs with up to 10%

tube plugging per steam generator and the increased value of 370,000 gpm for the minimum RCS flow rate. The current SBLOCA analysis models the OSGs with up to 2,500 plugged tubes (approximately 30% tube plugging) per steam generator.

3

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS Fuel Design Changes The new SBLOCA analysis used limiting initial fuel rod conditions that bound the various fuel and cladding types present in Cycle 16, including U0 2 and erbia fuel rods and Zircaloy-4 and ZIRLOTM cladding.

Other Plant Parameter Changes In addition to the changes described above, the new SBLOCA analysis introduced several other changes to plant parameters used in the analysis. The changes include the following:

Reduction in the high pressure safety injection pump flow Elimination of credit for charging pump flow Increase of 10 psi in the opening pressure of the first bank of the main steam safety valves Change in the PLHGR to 14.3 kW/ft Results and Conclusion of the New SBLOCA Analysis Tables 3 and 4 compare important inputs and results from the new SBLOCA analysis to those of the current SBLOCA analysis. A more detailed description of the new analysis, including tables and figures that present the results of the break spectrum analysis, will be incorporated into a future revision of the CCNPP Updated Final Safety Analysis Report.

As summarized below, the results of the new SBLOCA analysis conform to the acceptance criteria of 10 CFR 50.46(b).

Parameter Criterion Result Peak Cladding Temperature

• <22000 F 1955 0F Maximum Cladding Oxidation

• 17 %

9.03 %

Maximum Core-Wide Oxidation

• 1 %

<0.81 %

Coolable Geometry Yes Yes The new SBLOCA analysis uses the S2M, which is accepted by the NRC for licensing applications for Combustion Engineering designed PWRs such as CCNPP.

The analysis complies with the limitations/constraints imposed by all applicable SERs. The analysis uses values for plant design data that are either applicable to or bound the configuration of Unit 1 Cycle 16. Calvert Cliffs Nuclear Power Plant, Inc. and Westinghouse have ongoing processes that ensure that the as-operated plant values for PCT-sensitive parameters remain bounded by the values used in the analysis.

Applicability of the New Analyses to Unit 2 The new LBLOCA and SBLOCA analyses were performed to be applicable to both Unit 1 and Unit 2 after the RSGs are installed. The RSGs are scheduled to be installed in Unit 2 in the spring of 2003 during the refueling outage prior to startup of Cycle 15. As part of the Unit 2 Cycle 15 reload analysis activities, CCNPP and Westinghouse will confirm the applicability of the new analyses to Unit 2 Cycle 15, by ensuring that the Cycle 15 values for PCT-sensitive parameters are bounded by the values used in the new analyses. When it is confirmed that the new analyses are applicable to Unit 2, CCNPP will incorporate the change into the Updated Final Safety Analysis Report. A separate 30-day report to the NRC detailing these same changes to the Unit 2 ECCS performance analysis will not be submitted 4

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS unless there are changes to Unit 2 analysis that cause it to differ from the analysis methods and results described in this letter.

Summary The new LBLOCA and SBLOCA analyses comply with 10 CFR 50.46 as follows:

The analyses were performed with acceptable evaluation models and included sensitivity studies that assured the limiting LBLOCA and SBLOCA were analyzed [10 CFR 50.46(a)(1)(i)].

The results of the new LBLOCA and SBLOCA analyses conform to the ECCS acceptance criteria

[10 CFR 50.46(b)].

This 30-day report provides NRC with notification of the change in the application of the evaluation models and their effect on the limiting ECCS analyses [10 CFR 50.46(a)(3)(ii)].

The new LBLOCA and SBLOCA analyses constitute new licensing basis analyses (analyses-of-record).

They will be used as the reference analyses to evaluate the impact on PCT of future changes to or errors in the 1999 EM and the S2M, and their application to CCNPP.

References

1.

CENPD-132, Supplement 4-P-A, "Calculative Methods for the CE Nuclear Power Large Break LOCA Evaluation Model," March 2001

2.

CENPD-404-P-A, Revision 0, "Implementation of ZIRLOTM Cladding Material in CE Nuclear Power Fuel Assembly Designs," November 2001

3.

Letter from Mr. S. A. Richards (NRC) to Mr. P. W. Richardson (Westinghouse), dated December 15, 2000, "Safety Evaluation of Topical Report CENPD-132, Supplement 4, Revision 1, 'Calculative Methods for the CE Nuclear Power Large Break LOCA Evaluation Model' (TAC No. MA5660)"

4.

Letter from Mr. S. A. Richards (NRC) to Mr. P. W. Richardson (Westinghouse), dated September 12,

2001, "Safety Evaluation of Topical Report CENPD-404-P, Revision 0,

'Implementation of ZIRLO Material Cladding in CE Nuclear Power Fuel Assembly Designs' (TAC No. MB 1035)"

5.

Letter from Mr. C. H. Cruse (CCNPP) to NRC Document Control Desk, dated July 27, 2001, "License Amendment Request:

Incorporate Methodology References for the Implementation of ZIRLO Clad Fuel Rods into the Technical Specifications"

6.

Letter from Ms. D. Skay (NRC) to Mr. C. H. Cruse (CCNPP), dated April 8, 2002, "Calvert Cliffs Nuclear Power Plant, Unit Nos. 1 and 2 Amendment Re: Implementation of ZIRLO Clad Fuel Rods (TAC Nos. MB2540 and MB2541)"

7.

CENPD-132, Supplement 3-P-A, "Calculative Methods for the C-E Large Break LOCA Evaluation Model for the Analysis of C-E and W Designed NSSS," June 1985

8.

CENPD-137, Supplement 2-P-A, "Calculative Methods for the ABB CE Small Break LOCA Evaluation Model," April 1998

9.

Letter from Mr. T. H. Essig (NRC) to Mr. I. C. Rickard (ABB Combustion Engineering), dated December 16, 1997, "Acceptance for Referencing of the Topical Report CENPD-137(P),

Supplement 2, 'Calculative Methods for the C-E Small Break LOCA Evaluation Model' (TAC No.

M95687)"

5

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS

10. CENPD-137, Supplement 1-P, "Calculative Methods for the C-E Small Break LOCA Evaluation Model," January 1977 Table 1 Comparison of Important Parameters Used in the Current and New CCNPP Unit 1 LBLOCA ECCS Performance Analysis Current New Analysis Parameter Analysis LBLOCA Evaluation Model 1985 EM 1999 EM Core Power Level, MWt (including power 2754 2754 measurement uncertainty)

Peak Linear Heat Generation Rate, kW/ft 13.9 14.3 Hot Rod Pin-to-Box Factor 1.03 1.025 RCS Flow Rate, gpm 340,000 370,000 RCS Pressure, psia 2250 2250 Cold Leg Temperature 546 546 Hot Leg Temperature 601 597 Steam Generators OSGs RSGs Steam Generator Tube Plugging, plugged tubes/SG 2500 847 Table 2 Comparison of Important Results of the Current and New CCNPP Unit 1 LBLOCA ECCS Performance Analysis Parameter Limiting Break Size Peak Cladding Temperature, OF Time of Peak Cladding Temperatu Maximum Cladding Oxidation, %

Maximum Core-Wide Cladding 0 Time of Cladding Rupture 6

re, seconds xidation, %

(a) DEG/PD = Double-Ended Guillotine Break in Pump Discharge Leg

ATTACHMENT (1) 10 CFR 50.46 THIRTY-DAY REPORT FOR CHANGES TO THE CALVERT CLIFFS NUCLEAR POWER PLANT EMERGENCY CORE COOLING SYSTEM PERFORMANCE ANALYSIS Table 3 Comparison of Important Parameters Used in the Current and New CCNPP Unit 1 SBLOCA ECCS Performance Analysis Current Parameter Analysis New Analysis SBLOCA Evaluation Model SiM S2M Core Power Level, MWt (including power 2754 2754 measurement uncertainty)

Peak Linear Heat Generation Rate, kW/ft 14.5 14.3 RCS Flow Rate, gpm 340,000 370,000 RCS Pressure, psia 2250 2250 Cold Leg Temperature 546 550 Hot Leg Temperature 601 601 Steam Generators OSGs RSGs Steam Generator Tube Plugging, plugged tubes/SG 2500 847 Table 4 Comparison of Important Results of the Current and New CCNPP Unit 1 SBLOCA ECCS Performance Analysis Parameter Current Analysis New Analysis Limiting Break Size(a) 0.1 ftf/PDcb) 0.08 ft2/PD Peak Cladding Temperature, 'F 1985 1955 Time of Peak Cladding Temperature, seconds 1403 1293 Maximum Cladding Oxidation, %

5.42 9.03(c)

Maximum Core-Wide Cladding Oxidation, %

<0.80

<0.81 Time of Cladding Rupture 1027 1125 7

(a) Break that resulted in the highest peak cladding temperature.

(b)

PD = Pump Discharge Leg (c) The 0.06 ft2/PD break produced the maximum cladding oxidation.