L-2012-355, Nuclear Fuel Pellet Thermal Conductivity Degradation Impact on Current Cycle 26 Be LBLOCA Analysis Using the 1996 Cqd Methodology 10 CFR 50.46 30-Day Special Report

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Nuclear Fuel Pellet Thermal Conductivity Degradation Impact on Current Cycle 26 Be LBLOCA Analysis Using the 1996 Cqd Methodology 10 CFR 50.46 30-Day Special Report
ML12292A570
Person / Time
Site: Turkey Point NextEra Energy icon.png
Issue date: 10/03/2012
From: Kiley M
Florida Power & Light Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2012-355
Download: ML12292A570 (14)
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Florida Power & Light Company, 9760 S.W. 344 Street, Florida City, FL 33035 0 October 3, 2012 FPL L-2012-355 POWERING TODAY. 10 CFR 50.46 EMPOWERING TOMORROW.

U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re: Turkey Point Unit 4 Docket No. 50-251 Nuclear Fuel Pellet Thermal Conductivity Degradation Impact on current Turkey Point Unit 4 Cycle 26 BE LBLOCA Analysis using the 1996 CQD Methodology 10 CFR 50.46 30-Day Special Report

References:

1. Letter from M. Kiley (FPL)to U.S. Nuclear Regulatory Commission (L-2012-204), "Turkey Point Units 3 and 4, Docket Nos. 50-250 and 50-251, "10CFR 50.46 'Acceptance Criteria for Emergency Core Cooling Systems in Light Water Nuclear Power Reactors,' - 2011 Annual Report," April 30, 2012.
2. NRC Information Notice 2011-21, "Realistic Emergency Core Cooling System Evaluation Model Effects Resulting From Nuclear Fuel Thermal Conductivity Degradation," December 13, 2011.
3. WCAP-14159 Rev. 0, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for Turkey Point Units 3 & 4 Nuclear Power Plant for Power Uprate," October 1996.
4. NRC Letter from J. C. Paige (NRC) to M. Nazar, "Turkey Point Units 3 and 4 - Issuance of Amendments Regarding Extended Power Uprate (Tac Nos. ME4907 and ME4908),"

Amendments 249 and 245, June 15, 2012.

Florida Power & Light Company (FPL) letter L-2012-204 (Reference 1), documented the 2011 Annual Report of Peak Clad Temperature (PCT) for the Small Break Loss of Coolant Accident (SBLOCA) and the Large Break Loss of Coolant Accident (LBLOCA) for Turkey Point Units 3 and 4. The reported LBLOCA PCT and cumulative change were 1998 OF and 283 OF, respectively.

Nuclear Regulatory Commission (NRC) Information Notice 2011-21 (Reference 2) notified addressees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted peak clad temperature (PCT) results in realistic emergency core cooling system (ECCS) evaluation models.

Turkey Point Unit 4 Cycle 26 is currently operating and will continue to operate at pre-EPU (Extended Power Uprate) conditions until the start of the refueling outage, currently scheduled in November 2012. Turkey Point Unit 4 Cycle 26 pre-EPU operation is licensed under the LBLOCA 1996 Code Qualification Document (CQD) methodology (Reference 3). Fuel pellet thermal conductivity degradation (TCD) was not explicitly considered in the pre-EPU Turkey Point Unit 4 LBLOCA Analysis of Record (AOR).

A,oc2 an FPL Group company

L-2012-355 Page 2 of 2 Westinghouse Electric Company, LCC letter NF-FP-12-182 dated September 4, 2012, provided FPL the results of the evaluation performed to address the impact of the TCD effects on the Turkey Point Unit 4 Cycle 26 LBLOCA EM.

10 CFR 50.46(a)(3)(ii) requires that changes to the LBLOCA Evaluation Model (EM) and SBLOCA EM PCT exceeding 50 OF have to be reported to the NRC within 30 days. This letter documents the impact of the nuclear fuel pellet TCD effects on the Turkey Point Unit 4 Cycle 26 LBLOCA EM and fulfills the 30-day reporting requirement. summarizes the evaluations and assessments made to the CQD LBLOCA EM for Unit 4 Cycle 26 to account for TCD effects. Table 2 in Enclosure 1 provides a summary of the PCT assessments for Unit 4 Cycle 26 which includes TCD effects with power peaking burndown, margin recovery changes, necessary code version changes and an error in the containment backpressure spilling assumption. Enclosure 2 provides a more detailed description of the above evaluations and assessments. The new LBLOCA predicted values for Unit 4 Cycle 26 PCT and the cumulative change are 1917 OF and 811 OF, respectively.

10 CFR 50.46(a) (3) (ii) also requires that a schedule for reanalysis be provided or compliance with the requirements of the regulation be shown. Continued compliance with 10 CFR 50.46 requirements is demonstrated by the total estimated new PCT value of 1917 OF being well below the limit of 2200 OF. However, a new LBLOCA analysis for both Turkey Point Units operating at EPU conditions which explicitly accounts for the effects of TCD has already been reviewed and approved by the NRC in Reference 4. Unit 4 is scheduled to start the next cycle (Cycle 27) at EPU conditions in early 2013 and Unit 3 is already operating on its first cycle (Cycle 26) at EPU conditions.

Should there be any questions, please contact Robert Tomonto, Licensing Manager, at 305-246-7327.

Very truly yours, Michael Kiley U Vice President Turkey Point Nuclear Plant Enclosures cc: Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant

L-2012-355 Enclosure 1 Page 1 of 7 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 1.0 Introduction The latest 10 CFR 50.46 ECCS Annual Report for Turkey Point Units 3 and 4 in Reference 1 documented the Best Estimate Large Break Loss of Coolant Accident (BE LBLOCA) PCT value for both Turkey Point Units at pre-EPU conditions based on the Westinghouse 1996 Code Qualification Document (CQD) Methodology (Reference 2). Unit 3 was shutdown for a refueling outage in early 2012 and the new cycle is operating at the Extended Power Uprate (EPU) conditions. The BE LBLOCA analyses at EPU conditions for both Turkey Point Units have been performed with the Westinghouse Automated Statistical Treatment of Uncertainty Method (ASTRUM) explicitly accounting for the effect of fuel pellet thermal conductivity degradation (TCD) as approved by the NRC in Reference 3. Unit 4 is still operating Cycle 26 at pre-EPU conditions and is scheduled to shutdown in November 2012 and start Cycle 27 at EPU conditions in the spring of 2013. The U.S. Nuclear Regulatory Commission (NRC) issued Information Notice (IN) 2011-21 (Reference 4) to notify licensees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity, and its potential to cause errors (specifically, higher predicted peak clad temperature (PCT) results) in realistic emergency core cooling system (ECCS) evaluation models. In response to NRC IN 2011-21, this report addresses the impact of TCD on the current pre-EPU Unit 4 Cycle 26 LBLOCA analysis.

1.1. References

1. Letter from M. Kiley (FPL) to U.S. Nuclear Regulatory Commission (L-2012-204), "Turkey Point Units 3 and 4, Docket Nos. 50-250 and 50-251, 10CFR 50.46, Acceptance Criteria for Emergency Core Cooling Systems in Light Water Nuclear Power Reactors," - 2011 Annual Report.
2. WCAP-14159 Rev. 0, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for Turkey Point Units 3 & 4 Nuclear Power Plant for Power Uprate," October 1996.
3. NRC Letter from J. C. Paige (NRC) to M. Nazar, "Turkey Point Units 3 and 4 - Issuance of Amendments Regarding Extended Power Uprate (Tac Nos. ME4907 and ME4908),"

Amendments 249 and 245, June 15, 2012.

4. NRC Information Notice 2011-21, "Realistic Emergency Core Cooling System Evaluation Model Effects Resulting from Nuclear Fuel Thermal Conductivity Degradation", December 13, 2011.

L-2012-355 Enclosure 1 Page 2 of 7 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 2.0 Assessments This section describes the ECCS BE LBLOCA changes to the pre-EPU CQD evaluation model to account for TCD effects and an error identified during the process of evaluating these effects.

The assessments account for TCD effects with power peaking burndown, margin recovery changes, necessary code version changes and an error in the containment backpressure spilling assumption.

Affected Evaluation Model 1996 Westinghouse Best Estimate Large Break LOCA Code Qualification Document (CQD)

Evaluation Model 2.1. Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown 2.1.1. Background Fuel pellet thermal conductivity degradation (TCD) and peaking factor burndown were not explicitly considered in the pre-EPU (Extended Power Uprate) Turkey Point Unit 4 Large Break Loss-of-Coolant Accident (LBLOCA) Analysis of Record (AOR). Nuclear Regulatory Commission (NRC) Information Notice 2011-21 (Reference 1) notified addressees of recent information obtained concerning the impact of irradiation on fuel thermal conductivity and its potential to cause significantly higher predicted peak clad temperature (PCT) results in realistic emergency core cooling system (ECCS) evaluation models. This evaluation provides an estimated effect of TCD and peaking factor burndown on the PCT calculation for the ECCS at Turkey Point Unit 4. This change represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-1 3451 (Reference 2).

2.1.2. Estimated Effect A quantitative evaluation using a method similar to that described in Reference 3 was performed to assess the PCT effect of TCD and peaking factor burndown with other considerations of burnup on the Turkey Point Unit 4 LBLOCA analysis and concluded that the estimated PCT impact is a penalty of 60'F for Reflood 1 and a penalty of 270°F for Reflood 2 for 10 CFR 50.46 reporting purposes. The evaluation herein differs from that in Reference 3 because it utilizes a different burnup selection and the code version changes are more extensive. The peaking factor burndown included in the evaluation is provided in Table 1. FPL and Westinghouse Electric Company LLC utilize processes which ensure that the Loss-of-Coolant Accident (LOCA) analysis input values conservatively bound the as-operated plant values for those parameters.

L-2012-355 Enclosure 1 Page 3 of 7 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 Table 1: Peaking Factors Assumed in the Evaluation of TCD Rod Burnup FdH (1),(2) FQ Transient (1) FQ Steady-State (MWd/MTU) 0 1.63 2.47 1.94 30,000 1.63 2.47 1.94 49,000 1.30 1.785 1.40 62,000 1.30 1.785 1.40 (1) Includes uncertainties.

(2) Hot assembly average power follows the same burndown, since it is a function of FdH.

2.1.3. References

1. NRC Information Notice 2011-21, "Realistic Emergency Core Cooling System Evaluation Model Effects Resulting From Nuclear Fuel Thermal Conductivity Degradation," December 13, 2011.
2. WCAP-1 3451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting," October 1992.
3. LTR-NRC-12-27, Letter from J. A. Gresham (Westinghouse) to NRC, 'Westinghouse Input Supporting Licensee Response to NRC 10 CFR 50.54(f) Letter Regarding Nuclear Fuel Thermal Conductivity Degradation (Proprietary/Non-Proprietary)," March 7, 2012.

L-2012-355 Enclosure 1 Page 4 of 7 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 2.2. Evaluation of Design Input Changes with Respect to Plant Operation 2.2.1. Background To provide more margin to the 10 CFR 50.46(b)(1) acceptance criterion concerning peak cladding temperature (PCT) when explicitly considering fuel pellet thermal conductivity degradation (TCD) and peaking factor burndown in the Turkey Point Unit 4 Large Break Loss-of-Coolant Accident (LBLOCA) analysis, design input values were revised to more closely represent current plant operation. These input changes are not changes to the approved 1996 Westinghouse Best Estimate Large Break LOCA Evaluation Model, but represent changes in plant configuration, distinguished from evaluation model changes in Section 4 of WCAP-1 3451 (Reference 2). The updated inputs for Turkey Point Unit 4 include:

" Reduction in FdH

  • Reduction in hot assembly average power

" Reduction in Steady-State FQ

  • Increase in high head safety injection (HHSI) flow by crediting two HHSI pumps instead of one in the AOR. This is consistent with plant Technical Specifications and Emergency Operating Procedures.

FPL and Westinghouse Electric Company LLC utilize processes which ensure that the LOCA analysis input values conservatively bound the as-operated plant values for those parameters.

2.2.2. Estimated Effect A quantitative evaluation as discussed in Reference 1 was performed to estimate an overall PCT change due to changes in design input parameters. The evaluation concluded that the estimated PCT benefit of these design input changes is -34 0 F for Reflood 1 and -69 0 F for Reflood 2 for 10 CFR 50.46 reporting purposes.

2.2.3. References

1. LTR-NRC-12-27, Letter from J. A. Gresham (Westinghouse) to NRC, "Westinghouse Input Supporting Licensee Response to NRC 10 CFR 50.54(f) Letter Regarding Nuclear Fuel Thermal Conductivity Degradation (Proprietary/Non-Proprietary)," March 7, 2012.
2. WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting," October 1992.

L-2012-355 Enclosure 1 Page 5 of 7 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 2.3. Evaluation of Code Version Changes 2.3.1. Background Based on the methodology in Reference 1, WCOBRA/TRAC Version Mod 7A, Rev. 7 and HOTSPOT Version 6.1 are required to adequately model fuel thermal conductivity degradation (TCD). The Turkey Point Unit 4 Large Break Loss-of-Coolant Accident (LBLOCA) Analysis of Record (AOR) was performed using WCOBRA/TRAC Version Mod 7A, Rev. 1 and HOTSPOT Version 1.0. Individual code changes have been previously reported against the Turkey Point Unit 4 AOR; however, given the number of code changes, it was determined that the analysis should be rebaselined to the code versions used in the assessment of TCD. This change represents a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-1 3451 (Reference 2).

2.3.2. Estimated Effect A quantitative evaluation was performed to estimate an overall peak cladding temperature (PCT) change due to changes in code version. The evaluation concluded that the estimated PCT impacts of these changes are benefits of -201 OF for Reflood 1 and -151 OF for Reflood 2 for 10 CFR 50.46 reporting purposes.

2.3.3. References

1. LTR-NRC-1 2-27, Letter from J. A. Gresham (Westinghouse) to NRC, 'Westinghouse Input Supporting Licensee Response to NRC 10 CFR 50.54(f) Letter Regarding Nuclear Fuel Thermal Conductivity Degradation (Proprietary/Non-Proprietary)," March 7, 2012.
2. WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting," October 1992.

L-2012-355 Enclosure 1 Page 6 of 7 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 2.4. Evaluation of the Error in the Containment Backpressure Spilling Assumption 2.4.1. Background A potential inconsistency was discovered in the containment backpressure spilling assumption used for the residual heat removal (RHR) flows in the Turkey Point Unit 4 Analysis of Record (AOR). To demonstrate acceptability, the containment model was updated, taking credit for several margin sources which more accurately represent plant configuration. A new containment backpressure curve was calculated with the updated inputs.

These containment model input changes are not changes to the approved 1996 Westinghouse Best Estimate (BE) Large Break Loss-of-Coolant Accident (LBLOCA)

Evaluation Model, but represent changes in plant configuration, distinguished from evaluation model changes in Section 4 of WCAP-1 3451 (Reference 1).

2.4.2. Estimated Effect The calculated containment pressure with the revised inputs confirms that the analyzed RHR flows are acceptable. The analyzed containment pressure remains less than the calculated pressure using the revised inputs. As such, the estimated PCT impact of these containment model input changes is 0 OF for both Reflood 1 and Reflood 2 for 10 CFR 50.46 reporting purposes.

2.4.3. References

1. WCAP-13451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting," October 1992.

3.0 Conclusion These assessments result in the limiting PCT shifting from Reflood 1 to Reflood 2. Table 2 presents the limiting Reflood 2 PCT and the related assessments. The previously reported assessments are also shown in Table 2. Several assessments differ from that reported in the previous Turkey Point Units 3 & 4 - 10 CFR 50.46 reports due to the limiting PCT shifting from Reflood 1 to Reflood 2 as a result of the TCD & Peaking Factor Burndown assessment. Also, several previously reported individual assessments are included in the code rebaseline item.

The magnitude of the individual assessments have been removed from the code rebaseline item such that it represents only the net effect of handling these individual assessments integrally as well as the effects of all other code changes between the Analysis of Record (AOR) code versions and those required for the TCD evaluation. provides additional information regarding the assessments discussed in Section 2.0, above.

L-2012-355 Enclosure 1 Page 7 of 7 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 TABLE 2 TURKEY POINT UNIT 4 CYCLE 26 BE LBLOCA PCT Peak Cladding Cumulative Temperature Change EVALUATION MODELU1 )

Analysis of Record 2040 OF PREVIOUSLY REPORTED ERRORS AND CHANGES(a)

Vessel Channel DX Error -4 OF 4 OF MONTECAF Decay Heat Uncertainty Error 8 OF 8 OF RCP Reference Conditions Error -93 OF 93 OF Revised Blowdown Heatup Uncertainty Distribution 5 OF 5 OF HOTSPOT Fuel Relocation Error 0 OF 0 OF Upgrade from PAD 3.4 to PAD 4.0 -118 OF 118 OF ZIRLO Cladding Evaluation 22 OF 22 OF Axial Power Distribution Range (PBOT/PMID) Evaluation -4 OF 4 OF Axial Power Distribution Range (PMID) Evaluation -28 OF 28 OF Effect of Containment Purging 27 OF 27 OF Transition Core (to Upgrade Fuel) 12 OF 12 OF 2012 ASSESSMENTS Code Version Rebaseline(b) -151 OF 151 OF Plant Operational Design Input Changes -69 OF 69 OF Evaluation of TCD & Peaking Factor Burndown 270 OF 270 OF Containment Backpressure Spilling Assumption Error 0 OF 0 OF 1917 OF 811 OF Notes a) Several assessments differ from that reported in the previous Turkey Point Units 3 & 4 - 10 CFR 50.46 Reports due to the limiting PCT shifting from Reflood 1 to Reflood 2 as a result of the TCD

& Peaking Factor Bumdown assessment.

b) The Code Version Rebaseline line item reflects the net effect of treating several previously reported assessments integrally, as well as the effects of all other code changes between the Analysis of Record (AOR) code versions and those required for the TCD evaluation.

References

1. WCAP-14159 Rev. 0, "Best Estimate Analysis of the Large Break Loss of Coolant Accident for Turkey Point Units 3 & 4 Nuclear Power Plant for Power Uprate," October 1996.

L-2012-355 Enclosure 2 Page 1 of 5 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 SUPPLEMENTARY INFORMATION 1.0 Background The Nuclear Regulatory Commission (NRC) approved 1996 Westinghouse Best Estimate Large Break Loss-of-Coolant Accident (LOCA) Evaluation Model (Reference 1) is based on the PAD 3.4 fuel performance code (Reference 2). Upon NRC approval of PAD 4.0 (Reference 3), its usage was extended to the 1996 Westinghouse Best Estimate Large Break LOCA Evaluation Model, as reported to the NRC in Reference 4. The Turkey Point Unit 4 Large-Break LOCA (LBLOCA) analysis utilized fuel rod design input from PAD 3.4, and an evaluation was later performed for PAD 4.0. PAD 3.4 and 4.0 were licensed without explicitly considering fuel pellet thermal conductivity degradation (TCD) with burnup. Explicit modeling of fuel pellet TCD in the fuel performance code leads to changes in the fuel rod design parameters beyond beginning-of-life which are input to the LBLOCA analysis. The effects of explicitly modeling fuel pellet TCD on the Turkey Point Unit 4 LBLOCA analysis (Reference 5) have been considered. The modeling of fuel pellet TCD is considered a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-1 3451 (Reference 6).

Fuel performance data that accounts for fuel pellet TCD (using an unlicensed model) was used as input to the Turkey Point Unit 4 evaluation. The new PAD fuel performance data was generated with a representative model that includes explicit modeling of fuel pellet TCD.

Therefore, the evaluations performed consider the fuel pellet TCD effects cited in NRC Information Notice 2011-21 (Reference 7).

2.0 Large Break LOCA Input Parameters and Assumptions The evaluation of Design Input Changes considered the following input parameter changes to the LBLOCA analysis:

  • Reduction in FdH (including uncertainties) from 1.733 to 1.63
  • Reduction in hot assembly average power (including uncertainties) consistent with reduction in FdH

" Reduction in Transient FQ (including uncertainties) from 2.5 to 2.47

  • Reduction in Steady-State FQ from 2.1 to 1.94
  • Increased high head safety injection (HHSI) flows The evaluation of Containment Model Input Changes considered the following input parameter changes to the LBLOCA analysis:

" Initial containment pressure increased from 12.7 psia to 14.7 psia

  • Maximum containment net free volume increase from 1,550,000 ft3 to 1,600,000 ft3

" Maximum number of fan coolers decreased from 3 to 2

" The containment purge modeling was updated consistent with the Extended Power Uprate (EPU) ASTRUM analysis treatment and inputs

  • Heat sink data was updated consistent with that used in the EPU ASTRUM analysis

L-2012-355 Enclosure 2 Page 2 of 5 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 SUPPLEMENTARY INFORMATION The evaluation of fuel TCD and peaking factor burndown considered the following input parameter changes to the LBLOCA analysis:

  • Fuel rod design data with PAD 4.0 + TCD
  • Peaking factor burndown shown in Table 1 Table 1: Peaking Factors Assumed in the Evaluation of TCD Rod Burnup FdH (1),(2) FQ Transient (1) FQ Steady State (MWd/MTU)________

0 1.63 2.47 1.94 30,000 1.63 2.47 1.94 49,000 1.30 1.785 1.40 62,000 1.30 1.785 1.40 (1) Includes uncertainties.

(2) Hot assembly average power follows the same burndown, since it is a function of FDH.

The input changes described above have been confirmed to bound the current operation of Turkey Point Unit 4, Cycle 26.

3.0 Large Break LOCA Description of Evaluation An explicit calculation was performed to assess the impact of rebaselining to updated code versions appropriate for the evaluation of fuel pellet TCD on the Turkey Point Unit 4 LBLOCA analysis. Specifically, the reference transient was rerun using the code versions required for the TCD evaluation, and a peak cladding temperature (PCT) impact was assigned based on the plant-specific run results. The magnitude of the benefit was adjusted to remove the existing assessments for the separate effects of the Vessel Channel DX Error, Revised Blowdown Heatup Uncertainty Distribution, and HOTSPOT Fuel Relocation Error line items. As such, the Code Version Rebaseline line item reflects the net effect of treating the Vessel Channel DX Error, Revised Blowdown Heatup Uncertainty Distribution, and HOTSPOT Fuel Relocation Error integrally, as well as the effects of all other code changes between the Analysis of Record (AOR) code versions and those required for the TCD evaluation.

Starting from the rebaselined case with the required code versions, the evaluation method described in Reference 8 for the calculation of the margin peak cladding temperature (PCT) was used to assess the impact of the reduction in maximum peaking factors and increased high head safety injection (HHSI) flows on the Turkey Point Unit 4 LBLOCA analysis. Specifically, the rebaseline reference transient was rerun at beginning-of-life (BOL) conditions with the reduced peaking factors, increased HHSI flows, PAD 4.0 fuel performance data, and ZIRLO1 cladding, and a PCT benefit was assigned based on the plant-specific run results. The magnitude of the benefit was adjusted to remove the existing assessments for the separate 1ZIRLO is a registered trademark in the United States of Westinghouse Electric Company LLC, its subsidiaries and/or its affiliates. This mark may be used and/or registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited.

L-2012-355 Enclosure 2 Page 3 of 5 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 SUPPLEMENTARY INFORMATION effects of the Upgrade from PAD Version 3.4 to PAD Version 4.0 and the ZIRLO Cladding Evaluation line items. As such, the Evaluation of Design Input Changes with Respect to Plant Operation line item reflects the net effect of treating the Upgrade from PAD Version 3.4 to PAD Version 4.0 and the ZIRLO Cladding integrally, in addition to reduced BOL peaking factor margin and increased HHSI flows.

Starting from the margin evaluation case with the required code versions, a quantitative evaluation using a method similar to that described in Reference 8 was performed to assess the PCT effect of TCD and peaking factor burndown with other considerations of burnup on the Turkey Point Unit 4 LBLOCA analysis. The evaluation herein differs from that in Reference 8 because it utilizes a different burnup selection and the code version changes are more extensive.

While calculating the total safety injection (SI) flows taking credit for the additional HHSI flows, it was discovered that the residual heat removal (RHR) flows used in the analysis of record (AOR) were based on a potentially unacceptable containment backpressure spilling assumption. As a result, the containment model was updated with several margin sources, which more accurately represent plant configuration. A new containment backpressure curve was calculated with the updated inputs. The calculated containment pressure with the revised inputs confirms that the analyzed RHR flows are acceptable. The analyzed containment pressure remains less than the calculated pressure using the revised inputs. As such, the estimated PCT impact of these containment model input changes is 0 OF for both Reflood 1 and Reflood 2.

4.0 Large Break LOCA Results The results of the evaluation of plant and containment input changes, fuel pellet thermal conductivity degradation and peaking factor burndown, and the rebaseline to newer code versions are presented in Table 2.

Table 2: Fuel Pellet TCD and Code Version Evaluation Results Evaluation Reflood 1 APCT Reflood 2 APCT (OF) (OF)

TCD (including burndown) 60 270 BOL Peaking Factors and -34 -69 Increased HHSI Containment Backpressure Spilling 0 0 Assumption Error Code Version Rebaseline -201 -151

L-2012-355 Enclosure 2 Page 4 of 5 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 SUPPLEMENTARY INFORMATION With these new evaluations, acceptance criterion 10 CFR 50.46(b)(1) is met as follows:

  • Calculated Peak Clad Temperature (PCT) = 1917 OF < 2200 OF A qualitative evaluation was performed and determined that the existing Maximum Local Oxidation (MLO) and Calculated Core Wide Oxidation (CWO) results remain bounding of the results considering TCD and the other modeling updates herein. As such, acceptance criteria 10 CFR 50.46(b)(2) and (b)(3) are met as follows:

" Calculated Maximum Local Oxidation (MLO) = 13.6% < 17%

" Calculated Core Wide Oxidation (CWO) = 0.98% < 1%

Based on the PCT and oxidation results herein, and the existing grid crush calculations, it was determined that acceptance criterion 10 CFR 50.46(b)(4) continues to be met.

Based on the demonstration of coolable geometry, and because long term core cooling continues to be maintained with the evaluation and input changes herein, it was determined that acceptance criterion 10 CFR 50.46(b)(5) continues to be met.

As a result, all of the 10 CFR 50.46 acceptance criteria are met for the Turkey Point Unit 4 LBLOCA analysis when considering the code version changes, modeling changes with respect to plant operation, containment backpressure spilling assumption error, and changes for TCD evaluated herein.

5.0 References

1. WCAP-12945-P-A, Volume 1, Revision 2, and Volumes 2 through 5, Revision 1, "Code Qualification Document for Best Estimate LOCA Analysis," March 1998.
2. WCAP-10851-P-A, "Improved Fuel Performance Models for Westinghouse Fuel Rod Design and Safety Evaluations," August 1988.
3. WCAP-1 5063-P-A with Errata, Revision 1, "Westinghouse Improved Performance Analysis and Design Model (PAD 4.0)," July 2000.
4. LTR-NRC-01-6, "10 CFR 50.46 Annual Notification and Reporting for 2000," March 13, 2001.
5. WCAP-14159, Rev. 0, "Best-Estimate Analysis of the Large Break Loss of Coolant Accident for Turkey Point Units 3 & 4 Nuclear Plant for Power Uprate," October 1996.
6. WCAP-1 3451, "Westinghouse Methodology for Implementation of 10 CFR 50.46 Reporting,"

October 1992.

L-2012-355 Enclosure 2 Page 5 of 5 10 CFR 50.46 30-DAY REPORT ON IMPACT OF TCD ON THE TURKEY POINT UNIT 4 CYCLE 26 SUPPLEMENTARY INFORMATION

7. NRC Information Notice 2011-21, "Realistic Emergency Core Cooling System Evaluation Model Effects Resulting From Nuclear Fuel Thermal Conductivity Degradation," December 13, 2011.
8. LTR-NRC-12-27, "Westinghouse Input Supporting Licensee Response to NRC 10 CFR 50.54(f) Letter Regarding Nuclear Fuel Thermal Conductivity Degradation (Proprietary/Non-Proprietary)," March 7, 2012.
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