NOC-AE-16003422, CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes and Annual Report

CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes and Annual Report

ML16336A637
Person / Time
Site:	South Texas
Issue date:	11/22/2016
From:	Dunn R South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-16003422
Download: ML16336A637 (8)

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Nuclear Operating Company South Texas Project Electric Generating Statio11 l!O. Box 289 Wadsworth. Tex.1s 77483 November 22, 2016 NOC-AE-16003422 10 CFR 50.46 (a)(3)(i) 10 CFR 50.46 (a)(3)(ii)

U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 South Texas Project Units 1&2 Docket Nos. STN 50-498, STN 50-499 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes and Annual Report

References:

1. Letter from R. F. Dunn to NRC, 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes, dated February 24, 2016, NOC-AE-16003341 (ML16103A512)

2. Letter from R. F. Dunn to NRC, Thirty-Day Report of Significant ECCS Model Changes and Annual Report, dated June 9, 2015, NOC-AE-15003249 (ML15177A012)

In accordance with the requirements of 10 CFR 50.46 (a)(3)(i), STP Nuclear Operating Company (STPNOC) is submitting a 30-day report for a significant change in the South Texas Unit 2 Emergency Core Cooling Model. In addition, the annual report for South Texas Project Units 1 and 2 is also provided in the attachment in accordance with 10 CFR 50.46 (a)(3)(ii).

In Reference 1, STPNOC notified the NRC that for Unit 1Cycle20 there was no peak clad temperature (PCT) penalty due to gamma energy deposition model (GEDM) violation, and the Large Break loss-of-coolant accident (LOCA) PCT was reduced from 2120°F back to 21l7°F.

Therefore, there is no change to the Unit 1 Large Break LOCA PCT. Also, there is no change to the PCT for Small Break LOCA. -

In Reference 2, STPNOC notified the NRC that the Unit 2 Cycle 18 Large Break LOCA PCT had increased by 8°F due to an increase of the hot assembly average rod GEDM and hot rod calculated values. As a result, the Unit 2 Cycle 18 PCT had increased from 21l7°F to 2125°F.

For the current Unit 2 Cycle 19, there is no GEDM PCT~penalty, so the PCT is reduced by 8°F from 2125°F back to 21l7°F. Since the absolute value of PCT changes to the Analysis of Record exceeds 50°F, the change is considered significant in accordance with 10 CFR 50.46 (a)(3)(i). The PCT value for the Small Break LOCA is not changed.

STl34402484

NOC-AE-16003422 Page 2 of3 No schedule for reanalysis is proposed since both the Unit 1 and Unit 2 PCTs remain below the 10 CPR 50.46 (b)(l) limit of2200°F.

There are no commitments in this letter.

If there are any questions regarding this information, please contact Safdar Hafeez at 361-972-8906.

Roland F. Dunn Manager Nuclear Fuel and Analysis

Attachment:

Unit 1 & Unit 2 Annual Report (PCT Assessment)

NOC-AE-16003422 Page 3of3 CC:

(Paper Copy) (Electronic Copy)

Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Morgan, Lewis & Bockius LLP 1600 East Lamar Boulevard Steve Frantz, Esquire Arlington, TX 76011-4511 U.S. Nuclear Regulatory Commission Lisa M. Regner Lisa M. Regner Senior Project Manager U.S. Nuclear Regulatory Commission NRG South Texas LP One White Flint North (08H04) Chris O'Hara 11555 Rockville Pike Jim von Suskil Rockville, MD 20852 Skip Zahn NRC Resident Inspector CPS Energy U.S. Nuclear Regulatory Commission Kevin Pollo P. 0. Box 289, Mail Code: MNl 16 Cris Eugster Wadsworth, TX 77483 L. D. Blaylock City of Austin Elaina Ball John Wester Texas Dept. of State Health Services Helen Watkins Robert Free

Attachment NOC-AE-16003422 Page 1of5 Unit 1 & Unit 2 Annual Report (PCT Assessment)

GENERAL CODE MAINTENANCE

Background

Various changes have been made to enhance the usability of codes and to streamline future analyses. Examples of these changes include modifying input variable definitions, units and defaults; improving the input diagnostic checks; enhancing the code output; optimizing active coding; and eliminating inactive coding. These changes represent Discretionary Changes that will be implemented on a forward-fit basis in accordance with Section 4.1.1 ofWCAP-13451.

Affected Evaluation Model(s) 1981 Westinghouse Large-Break LOCA Evaluation with BASH 1985 Westinghouse Small Break LOCA Evaluation Model with NOTRUMP Estimated Effect The nature of these changes leads to an estimated Peak Cladding Temperature (PCT) impact of 0°F.

Attachment NOC-AE-16003422 Page 2of5 Unit 1 & Unit 2 Annual Report (PCT Assessment)

Westinghouse LOCA Peak Clad Temperature Summary for Appendix K Large Break Plant Name: South Texas Unit 1 Utility Name: STPNOC Analysislnformation EM: BASH Analysis Date: 7/1/1998 Limiting Break Size: Cd=0.8 FQ: 2.55 FdH: 1.62 Fuel: RFA I Vantage 5H SGTP(%): 10 Notes: 1. RFA Re-analysis - FdH = 1.55 for Once Burned Standard Fuel

2. Limiting Break run was performed with Min SI, Hi Tav, and IFBA Clad Temp {°F)

LICENSING BASIS Analysis-Of-Record PCT 2090 PCT Assessments (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. IMP Database Error Corrections 0

2. PAD Version 4.0 Implementation -30

3. LOCBART Pellet Volumetric Heat Generation Rate 6

4. PWROG TCD Evaluation - Rebaseline of AOR 5

5. PWROG TCD Evaluation- Effect ofTCD and Assembly o*

Power/Peaking Factor Bumdown B. PLANNED PLANT MODIFICATION EVALUATIONS

1. None 0 C. 2015 ECCS MODEL ASSESSMENTS

1. None 0 D. OTHER

1. Rebaseline of AOR 46 LICENSING BASIS PCT +PCT ASSESSMENTS 2117

Attachment NOC-AE-16003422 Page 3of5 Unit 1 & Unit 2 Annual Report (PCT Assessment)

Westinghouse LOCA Peak Clad Temperature Summary for Appendix K Small Break Plant Name: South Texas Unit 1 Utility Name: STPNOC Analysisinformation EM: NOTRUMP Analysis Date: 6/1/2000 Limiting Break 2 inch FQ: 2.7 FdH: 1.62 Fuel: RFA I Vantage SH SGTP (%): 10 Notes: 1. Delta 94 Replacement Steam Generator

2. Limiting Break run was performed with Hi Tavg, Hi Tmfw, and S2 Clad Temp (°F)

LICENSING BASIS Analysis-Of-Record PCT 1578 PCT Assessments (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. IMP Database Error Corrections 0

2. NOTRUMP Version 38.0 Namelist Error Correction 0

3. NOTRUMP Bubble Rise I Drift Flux Model Inconsistency 34 Corrections B. PLANNED PLANT MODIFICATION EVALUATIONS

1. None 0 C. 2015 ECCS MODEL ASSESSMENTS

1. None 0 D. OTHER

1. Burst and Blockage/Time in Life 0 LICENSING BASIS PCT +PCT ASSESSMENTS 1612

Attachment NOC-AE-16003422 Page 4of5 Unit 1 & Unit 2 Annual Report (PCT Assessment)

Westinghouse LOCA Peak Clad Temperature Summary for Appendix KLarge Break Plant Name: South Texas Unit 2 Utility Name: STPNOC Analysislnformation EM: BASH Analysis Date: 7/1/1998 Limiting Break Size: Cd=0.8 FQ: 2.55 FdH: 1.62 Fuel: RFA IVantage SH SGTP(%): 10 Notes: 1. RFA Re-analysis -FdH = 1.55 for Once Burned Standard Fuel

2. Limiting Break run was performed with Min SI, Hi-Tav, and IFBA Clad Temp (0 F)

LICENSING BASIS Analysis-Of-Record PCT 209U PCT Assessments (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. IMP Database Error Corrections 0 2 PAD Version 4.0 Implementation -30

3. LOCBART Pellet Volumetric Heat Generation Rate 6

4. PWROG TCD Evaluation - Rebaseline of AOR 5.

5. PWROG TCD Evaluation - Effect of TCD and Assembly 0 Power/Peaking Factor Bumdown B. PLANNED PLANT MODIFICATION EVALUATIONS

1. GEDM & Hot Rod Violation Evaluation 0 C. 2015 ECCS MODEL ASSESSMENTS

1. None 0 D. OTHER

1. Rebaseline of AOR 46 LICENSING BASIS PCT +PCT ASSESSMENTS 2117

Attachment NOC-AE-16003422 Page 5of5 Unit 1 & Unit 2 Annual Report (PCT Assessment)

Westinghouse LOCA Peak Clad Temperature Summary for Appendix K Small Break Plant Name: South Texas Unit 2 Utility Name: STPNOC Analysisinformation EM: NOTRUMP Analysis Date: 10/1/2000 Limiting Break 2 inch FQ: 2.7 FdH: 1.62 Fuel: RFA I Vantage SH SGTP (%): 10 Notes: 1. Delta 94 Replacement Steam Generator

2. Limiting Break run was performed with Hi Tavg, Hi Tmfw, and S2 Clad Temp (0 F)

LICENSING BASIS Analysis-Of-Record PCT 1578 PCT Assessments (Delta PCT)

A. PRIOR ECCS MODEL ASSESSMENTS

1. IMP Database Error Corrections 0

2. NOTRUMP Version 38.0 Namelist Error Correction 0

3. NOTRUMP Bubble Rise I Drift Flux Model Inconsistency 34 Corrections B. PLANNED PLANT MODIFICATION EVALUATIONS

1. None 0 C. 2015 ECCS MODEL ASSESSMENTS

1. None 0 D. OTHER

1. Burst and Blockage/Time in Life 0 LICENSING BASIS PCT+ PCT ASSESSMENTS 1612