ML12079A180

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Response to Information Request Pursuant to 10 CFR 50.54(f) Related to Estimated Effect on Peak Cladding Temperature Resulting from Thermal Conductivity Degradation in Westinghouse-Furnished Realistic..
ML12079A180
Person / Time
Site: Mcguire, Catawba, McGuire  Duke Energy icon.png
Issue date: 03/16/2012
From: Culp D
Duke Energy Carolinas
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
TAC M99899
Download: ML12079A180 (17)
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Text

David C. Culp Duke 10 CFR 50.54(f) Acting Vice President r* Energy. 10 CFR 50.46(a)(3)(ii) Nuclear Engineering Duke Energy Corporation 526 South ChurchStreet Charlotte, NC 28202 MailingAddress:

ECO8H / P. 0. Box 1006 Charlotte, NC 28201-1006 March 16, 2012 704 382 8833 704 382 7852 fax U. S. Nuclear Regulatory Commission David.Culp@duke-energy.com Attn: Document Control Desk Washington, DC 20555-0001

Subject:

Duke Energy Carolinas, LLC (Duke Energy)

Catawba Nuclear Station, Units 1 and 2, Docket Nos. 50-413, 50-414 McGuire Nuclear Station, Units 1 and 2, Docket Nos. 50-369, 50-370 Response to Information Request Pursuant to 10 CFR 50.54(f) Related to the Estimated Effect on Peak Cladding Temperature Resulting from Thermal Conductivity Degradation in the Westinghouse-Furnished Realistic Emergency Core Cooling System Evaluation and 30-Day Report Pursuant to 10 CFR 50.46, Changes to or Errors in an Evaluation Model

References:

1. Letter, M. G. Evans (NRC) to J. R. Morris (Duke Energy), "Catawba Nuclear Station, Units 1 and 2 - Information Request Pursuant to 10 CFR 50.54(f) Related to the Estimated Effect on Peak Cladding Temperature Resulting from Thermal Conductivity Degradation in the Westinghouse-Furnished Realistic Emergency Core Cooling System Evaluation (TAC NO. M99899)," February 16, 2012
2. Letter, M. G. Evans (NRC) to Regis T. Repko (Duke Energy), "McGuire Nuclear Station, Units 1 and 2 - Information Request Pursuant to 10 CFR 50.54(f) Related to the Estimated Effect on Peak Cladding Temperature Resulting from Thermal Conductivity Degradation in the Westinghouse-Furnished Realistic Emergency Core Cooling System Evaluation (TAC NO. M99899)," February 16, 2012
3. Letter, J. A. Gresham (Westinghouse) to USNRC Document Control Desk, "Westinghouse Input Supporting Licensee Response to NRC 10 CFR 50.54(f) Letter Regarding Nuclear Fuel Thermal Conductivity Degradation (Proprietary/Non-Proprietary)," LTR-NRC-12-27, March 07, 2012 On February 16, 2012 (References 1 and 2), the U.S. Nuclear Regulatory Commission (NRC) issued 10 CFR 50.54(f) letters regarding the impact on peak cladding temperature (PCT) from thermal conductivity degradation (TCD). This information is specific to the application of the Westinghouse Electric Company, LLC (Westinghouse) realistic emergency core cooling system evaluation and the potentially significant error, as defined in 10 CFR 50.46(a)(3)(i). The purpose of the request is to verify continued compliance with the PCT acceptance criterion for loss-of-coolant accidents (LOCAs) promulgated in 10 CFR 50.46(b)(1). Specifically, the calculated maximum fuel element cladding temperature shall not exceed 22000 F.

www.duke-energy.corn SAcoD

U.S. Nuclear Regulatory Commission March 16, 2012 Page 2 The purpose of this letter is twofold:

1. Pursuant to 10 CFR 50.54(f), Enclosure 1 contains Duke Energy's 30-day response for the requested information related to the Estimated Effect on Peak Cladding Temperature Resulting from Thermal Conductivity Degradation in the Westinghouse Furnished Realistic ECCS Evaluation for Catawba and McGuire Nuclear Stations;
2. Pursuant to 10 CFR 50.46(a)(3)(ii), Enclosure 2 contains a 30-day report required on the changes to or errors in the ECCS Evaluation Models. In support of Duke Energy's response, Westinghouse submitted directly to the NRC, a description of the methodology and assumptions used to determine the estimated PCT impact due to TCD.

References are found in Enclosure 3.

Commitments made by this letter:

Before December 15, 2016, Duke Energy will submit to the NRC for review and approval a LBLOCA analysis that applies an NRC-approved ECCS Evaluation Model that includes the effects of fuel thermal conductivity degradation.

Please address any comments or questions regarding this matter to Jeff Thomas at 704 382-3438 (Jeff.Thomas@duke-energy.com).

Sincerely, David 0. Culp : 10 CFR 50.54(f) Response : 10 CFR 50.46 Reporting Requirements : References

U.S. Nuclear Regulatory Commission March 16, 2012 Page 3 Oath or Affirmation David C. Culp affirms that he is the person who subscribed his name to matters in response to the 10 CFR 50.54(f) request as found in Enclosure 1 and that all the matters and facts set forth therein are true and correct to the best of his knowledge.

David C. Culp r Acting Vice President Nuclear Engineering Subscribed and sworn to me: /4, .O/ .1-cA_4, Date /

Notary Public ' /.: (,

My Commission Expires: c " (dpl.(e /

Date SEAL

U.S. Nuclear Regulatory Commission March 16, 2012 Page 4 xc:

V. M. McCree, Region II Administrator U.S. Nuclear Regulatory Commission Marquis One Tower 245 Peachtree Center Avenue NE, Suite 1200 Atlanta, Georgia 30303-1257 E. J. Leeds Director, Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 13-H16M Rockville, MD 20852-2738 J. H. Thompson, Project Manager U. S. Nuclear Regulatory Commission 11555 Rockville Pike Mail Stop 0-8 G9A Rockville, MD 20852-2738 J. Zeiler NRC Senior Resident Inspector McGuire Nuclear Station G. A. Hutto, III NRC Senior Resident Inspector Catawba Nuclear Station

U.S. Nuclear Regulatory Commission March 16, 2012 Page 1 of 6 Enclosure 1 10 CFR 50.54(f) Response The NRC has issued 10 CFR 50.54(f) letters to Catawba Nuclear Station and McGuire Nuclear Station [References 1 and 2] which request that, within 30 days of the letter date, Duke Energy provide information regarding the effect of a potentially significant error, as defined in 10 CFR 50.46(a)(3)(i), associated with fuel pellet thermal conductivity degradation (TCD), on peak cladding temperature (PCT) in the Westinghouse-furnished realistic emergency core cooling system (ECCS) evaluation model (EM). Specifically, the 10 CFR 50.54(f) letters indicated that the response shall address the following specific issues:

1) An estimation of the effect of the TCD erroron the peak fuel cladding temperature calculation for the emergency core cooling system evaluationsat Catawba 1 and 2/

McGuire I and 2.

2) A description of the methodology and assumptions used to determine the estimates. This description shall include consideration of experimental data relevant to TCD and specific information regardingany computer code model changes which were necessary to address these data.

Background

On December 13, 2011, the NRC held a conference call with Duke Energy and others in the industry to discuss the contents of Information Notice 2011-21 which would be issued on the same day. Duke Energy promptly entered the concerns raised by the NRC into the corrective action program and evaluated the potential impact of these concerns on continued safe operation of the plant. Westinghouse was contacted to evaluate the impact of these concerns.

The operability process was entered to evaluate the basis for continued operation by bounding the potential impacts with existing conservatism in the analysis of record.

Duke Energy Response to Question 1 The estimated impact on the Catawba / McGuire Best Estimate Large Break Loss of Coolant Accident (BELOCA) analysis of record PCT due to the effects of fuel pellet TCD represents a significant change or error in PCT for the limiting transient (reflood 2 for Catawba / McGuire), as defined in 10 CFR 50.46(a)(3)(i). This is due to the combination of:

1) a change in Westinghouse fuel performance code from PAD 3.4 to PAD 4.0 (both PAD versions are approved by NRC), resulting in a PCT change of -75 OF for both reflood 1 and reflood 2 (limiting PCT); and
2) an error estimating the effect of TCD using a fuel performance model labeled 'PAD 4.0 +

TCD', which has not been approved by the NRC, with peaking factor burndown, resulting in a PCT change of +114 OF for reflood 1, and a PCT change of +15 OF for reflood 2 (limiting PCT); and

3) Planned plant modification change associated with a proposed Measurement Uncertainty Recapture (MUR) power uprate analysis at McGuire. The effect on PCT of the MUR power uprate to 101.7% of 3411 MWt is +4 °F for reflood 1, and a PCT change of +16 OF for reflood 2 (limiting PCT).

U.S. Nuclear Regulatory Commission March 16, 2012 Page 2 of 6 Enclosure 1 The TCD assessment for impacts to Catawba / McGuire BELOCA PCT required usage of a separate ECCS model change which represents a change in fuel rod design input parameters from Westinghouse fuel performance code PAD 3.4 to PAD 4.0 without consideration of TCD.

In References 3 and 7, Westinghouse quantified a reflood phase PCT reduction of 75 0 F for the Catawba / McGuire BELOCA analysis when PAD 4.0 results for initial fuel temperatures were considered, as compared to the PAD 3.4 results. Specifically, the fuel temperature and rod internal pressure inputs from the PAD 3.4 data to PAD 4.0 were updated in the reference transient, and the 75 OF PCT reduction was assigned based on the plant-specific results. Then, the impact of TCD on PCT was evaluated separately, as a change from PAD 4.0 to "PAD 4.0 +

TCD" and peaking factor burndown, to provide an estimated effect from TCD that does not include unrelated PAD version differences. This evaluation resulted in an increase of 15°F for the Catawba / McGuire BELOCA analysis for reflood 2 (limiting PCT).

In addition, the effects of a proposed Measurement Uncertainty Recapture (MUR) power uprate are also included in the TCD evaluation because Duke Energy has recently submitted a License Amendment Request for an MUR power uprate at McGuire [Reference 4]. The effects are included herein for completeness because the TCD assessment performed by Westinghouse for Catawba / McGuire also addressed MUR conditions. Including the effects of the MUR resulted in a PCT increase of 16'F.

Table 1 summarizes the estimated effects of these changes on the Catawba / McGuire BELOCA limiting PCT. To date, an MUR power uprate License Amendment Request has not been submitted for Catawba, so the 160 F PCT impact is not included in PCT summary Table 1 below for Catawba.

Table I Composite Large Break LOCA PCT for Catawba / McGuire Including TCD PCT for Reflood 2 (OF)

Currently Reported Limiting PCT 2145 2012 ECCS Model Assessments Change from PAD 3.4 to PAD 4.0 -75 Change from PAD 4.0 to "PAD 4.0 + TCD" and Peaking Factor Burndown 15 Planned Plant Modification Evaluations McGuire MUR Uprate to 101.7% of 3411 MWt 16 Licensing Basis + PCT Assessments for McGuire 2101 Licensing Basis + PCT Assessments for Catawba 2085 Additional Information Supporting Duke Energy Response to Question I For Large Break Loss of Coolant Accidents, Catawba and McGuire are currently licensed to the Westinghouse "Code Qualification Document (CQD) for Best Estimate LOCA Analysis" Evaluation Model [Reference 5]. A composite BELOCA analysis of record is performed, which is bounding for Catawba Units 1 & 2 and McGuire Units 1 & 2. To characterize the BELOCA

U.S. Nuclear Regulatory Commission March 16, 2012 Page 3 of 6 Enclosure 1 event, the CQD EM develops PCT values for the blowdown, first reflood, and second reflood phases of the transient. The limiting PCT result for the composite BELOCA analysis of record occurs in the second reflood time period, as shown in Catawba / McGuire UFSAR Section 15.6.5. The limiting second reflood PCTs for Catawba / McGuire have historically been reported to the NRC under 10 CFR 50.46, while the non-limiting first reflood PCTs have not been reported. For the sake of completeness, Duke Energy's response to this information request pursuant to 10 CFR 50.54(f) addresses both reflood phases of the BELOCA transient.

The NRC-approved CQD ECCS evaluation model is based on the PAD 3.4 fuel performance code. PAD 3.4 was licensed without explicitly considering fuel pellet TCD with burnup. Explicit modeling of fuel pellet TCD in the fuel performance code leads directly to increased fuel pellet temperatures. Increases in fuel pellet temperatures increase the stored energy in the fuel at the beginning of the simulated BELOCA event. For BELOCA, increased in stored energy in the fuel can lead to an increase in PCT ifoff-setting effects such as peaking factor burndown are not modeled.

The TCD assessment performed by Westinghouse for Catawba / McGuire is consistent with the approach detailed in Westinghouse letter to NRC dated March 7, 2012 [Reference 6]. New PAD fuel performance data was generated with a model that includes explicit modeling of fuel pellet TCD. The fuel performance data was used as input to the Catawba Units 1 & 2 and McGuire Units 1 & 2 evaluation.

By letters to Duke Energy dated March 7, 2012, Westinghouse provided the formal results of the TCD assessment for the composite Catawba / McGuire BELOCA analysis [References 7 and 8].

Westinghouse provided burnup-dependent peaking factor burndown curves to ensure that the composite LBLOCA analysis of record PCT for Catawba / McGuire remains valid. The functional form of the peaking factor burndown curves are shown below in Table 2.

Table 2 Normalized Peaking Factor Burndown Curves for Catawba / McGuire BELOCA PCT Hot Rod Average Burnup Normalized Fa Normalized FAH, Pbar (MWD/MTU) 0 1.0 1.0 35,000 1.0 1.0 55,000 0.9 0.95 62,000 0.8 0.9 In Table 1, normalized Fa applies to transient FQ and steady-state FQ. The values are normalized to Fa(transient) = 2.7 (with uncertainties) for the bottom third of the core, FQ(transient) = 2.5 (with uncertainties) for the top two-thirds of the core, FQ(steady-state) = 2.1 (without uncertainties), FAH = 1.67 (with uncertainties), and Pbar = 1.67/1.04 (with uncertainties).

Clarification note on Allowed Transient FQ Peaking Factor in the BELOCA analysis When the BELOCA analysis of record for Catawba / McGuire was initially performed in 2000, a transient FQ value of 2.5 was assumed for all core elevations. In 2010,

U.S. Nuclear Regulatory Commission March 16, 2012 Page 4 of 6 Enclosure I Westinghouse performed an assessment to examine impacts to the BELOCA analysis of record when a transient Fa allowance of 2.7 was considered for the bottom one-third of the core, i.e. core elevations between 0 and 4 feet. Westinghouse confirmed that there was no adverse impact to the limiting PCT in the reflood 2 time period [Reference 3]. This axial power shape PCT assessment (APCT = 28 OF for reflood 1 and a APCT = 0 °F for reflood 2) will be included in this response, as well as the Catawba / McGuire 10 CFR 50.46 annual report for the year 2011.

As noted earlier, the current composite Catawba / McGuire Best-Estimate Large Break LOCA analysis of record is based on fuel temperature predictions obtained from Westinghouse PAD computer code version 3.4. In 2000, Westinghouse received NRC approval for the PAD code version 4.0 [Reference 9]. For consistent inputs (e.g. same local linear heat rate and fuel type),

PAD 4.0 will predict lower fuel average temperatures than PAD 3.4. Lower initial fuel temperatures corresponds to lower stored energy in the core, and translates to lower PCT values during a postulated LBLOCA transient. At the time of PAD 4.0 approval by the NRC, Westinghouse indicated that its usage would be on a forward-fit basis, per Reference 9. The Catawba / McGuire Best-Estimate Large Break LOCA analysis of record was performed in 2000, and it has not been formally updated to reflect the newer PAD 4.0 results for initial fuel temperatures.

For the TCD assessments performed by Westinghouse, the PAD 4.0 code was modified to include TCD effects, as described by Westinghouse letter to the NRC dated March 7, 2012

[Reference 6]. As a result, the TCD assessment for Catawba / McGuire PCT required usage of a separate ECCS model change, which represents a change in fuel rod design input parameters from Westinghouse fuel performance code PAD 3.4 to PAD 4.0 without consideration of TCD.

In References 3 and 7, Westinghouse quantified a reflood phase PCT reduction of 75°F for the Catawba / McGuire BELOCA analysis when PAD 4.0 results for initial fuel temperatures were considered, versus the PAD 3.4 results. Specifically, the fuel temperature and rod internal pressure inputs from the PAD 3.4 data to PAD 4.0 were updated in the reference transient, and the 75 OF PCT benefit was assigned based on the plant-specific results. Then, the impact of TCD on PCT was evaluated separately, as a change from PAD 4.0 to "PAD 4.0 + TCD" and peaking factor burndown, to provide an estimated effect from TCD that does not include unrelated PAD version differences.

The results of the TCD assessment for Catawba / McGuire PCT are shown below in Table 3.

The effects of a proposed Measurement Uncertainty Recapture (MUR) power uprate are also included, as Duke Energy has recently submitted a License Amendment Request for an MUR power uprate at McGuire [Reference 4]. It is included herein for completeness, because the TCD assessment performed by Westinghouse for Catawba / McGuire also addressed MUR conditions. Including the effects of MUR resulted in a PCT increase of 16*F for McGuire. To date, an MUR power uprate License Amendment Request has not been submitted for Catawba, so the 160 F PCT impact is not included in PCT summary Table 3 below for Catawba.

U.S. Nuclear Regulatory Commission March 16, 2012 Page 5 of 6 Enclosure 1 Table 3 Catawba and McGuire Best Estimate LBLOCA Peak Cladding Temperatures Composite BELOCA PCT for Catawba / McGuire PCT for PCT for Reflood 1 (OF) Reflood 2 (OF)

Licensing Basis Analysis of Record PCT, as described in the UFSAR 1692 2028 Prior ECCS Model Assessments MONTECF Decay Heat Uncertainty Error 4 8 MONTECF Power Uncertainty Correction 8 20 Input Error Resulting in Incomplete Solution Matrix 1 25 Revised Blowdown Heatup Uncertainty Distribution 5 5 Plant Input / Modification Evaluations Safety Injection Temperature Range Evaluation 0 59 Currently Reported Limiting PCT 1710 2145

[Values below have not been previously reported]

2011 ECCS Model Assessments Axial Power Shape Evaluation 28 0 2012 ECCS Model Assessments Change from PAD 3.4 to PAD 4.0 -75 -75 Change from PAD 4.0 to "PAD 4.0 + TCD" and Peaking 114 15 Factor Burndown Planned Plant Modification Evaluations McGuire MUR Uprate to 101.7% of 3411 MWt 4 16 Licensing Basis + PCT Assessments for McGuire 1781 2101 Licensing Basis + PCT Assessments for Catawba 1777 2085 Plant-Specific Validation of Peaking Factor Burndown Curves used for TCD Assessment Cycle-specific analyses were performed by Duke Energy for all operating cores for Catawba and McGuire. Additionally, Catawba Unit 2 Cycle 19 (Catawba Unit 2 Cycle 18 shutdown on March 10, 2012, and Cycle 19 is scheduled to start operation in April of 2012) to verify the acceptability of the peaking factor burndown curves used in the TCD assessment. The cycle-specific analyses also confirmed the acceptability of LOCA operational Axial Flux Difference (AFD) limits and Monitoring Factors specified in the applicable Core Operating Limits Report (COLR). Steady-state FQ limits were verified by comparing code predictions of steady-state peaking factors from nominal rated thermal power conditions against the steady-state FQ peaking factor burndown curve shown in Table 2. Transient FQ, FAH, and Pbar limits were verified by comparing power distributions that could be produced from normal operational transients against applicable limits specified in Table 2. Transient power distributions were generated based on the methodology described in Reference 10, and were generated to span operational AFD limits and rod insertion limits. All calculations were performed with the NRC-approved CASMO-4/SIMULATE-3 methodology [Reference 11]. Cycle-specific confirmation of BELOCA initial condition assumptions and transient FQ, FAH, and Pbar limits are performed in Duke Energy calculations referred to as "maneuvering analysis".

U.S. Nuclear Regulatory Commission March 16, 2012 Page 6 of 6 Enclosure 1 The following cycle-specific core maneuvering analyses were revised to evaluate the acceptability of the revised BELOCA peaking factor burndown limits in Table 2:

Catawba 1 Cycle 20, Catawba 2 Cycle 18, Catawba 2 Cycle 19 McGuire 1 Cycle 22, McGuire 2 Cycle 21 Results from the cycle-specific core maneuvering analysis calculations confirmed the acceptability of steady-state FQ, transient FQ, Pbar and FAH initial condition input assumptions assumed in TCD assessment. The revised core maneuvering analyses also showed no change in the limiting transient FQ margins, verifying that fuel at burnups where TCD is a concern is non-limiting. This later result is important because it confirms the acceptability of the operational AFD limits and F0 Monitoring Factors specified in the COLR. Fuel at burnups where TCD is a concern is non-limiting because the reactivity, and therefore the power producing capability of the fuel, decreases with increasing burnup at a rate sufficient to offset the effects of the TCD peaking factor burndown curves. For the reactor cores analyzed, more peaking factor margin exists to the transient FAH and FQ limits at burnups where TCD starts becoming important (> 30 GWD/MTU) relative to the limiting FAH and FQ peaking factor margins in the core for burnups < 30 GWD/MTU.

In summary, it has been analytically demonstrated that limiting locations with respect to BELOCA peaking limits are not occurring in high burnup fuel, and the natural reduction in achievable local rod powers as a function of burnup is enough to satisfy the peaking factor burndown curves utilized in the TCD assessment. Therefore, the FQ(x,y,z) power distribution measurements required by Technical Specification 3.2.1 coupled with continuous global power distribution monitoring through Technical Specification 3.2.3 (Axial Flux Difference), Technical Specification 3.2.4 (Quadrant Power Tilt) and Technical Specification 3.1.6 (Control Bank Insertion Limits) will continue to provide assurance that the Catawba / McGuire reactor cores are operating as designed, and provide continued verification of the acceptability of the BELOCA analysis.

The peaking factor bumdown limits shown in Table 2 will be incorporated into Duke Energy's core reload design process for Catawba / McGuire, to ensure adequate verification of the bumup-dependent peaking factor limits used in the TCD assessment for future core designs.

Duke Energy Response to Question 2 Describing the methodologies and assumptions used to estimate PCT and to determine the effect of TCD as a function of burnup, Westinghouse submitted information to the NRC by letter dated March 7, 2012 [Reference 6]. This description includes consideration of experimental data relevant to TCD and specific information regarding any computer code model changes which were necessary to address these data.

As discussed in the response to Question 1, the TCD assessment for Catawba / McGuire required a separate step in which PCT impacts were quantified for an ECCS model change from PAD 3.4 to PAD 4.0. Both of these versions of PAD are approved by the NRC. The TCD impacts were then separately assessed using the "PAD 4.0 + TCD" version, which is described by Westinghouse in Reference 6.

U.S. Nuclear Regulatory Commission March 16, 2012 Page 1 of 5 Enclosure 2 10 CFR 50.46 Reporting Requirements The estimated impact on the Catawba / McGuire BELOCA analysis of record PCT due to the effects of fuel pellet TCD represents a significant change in PCT for the limiting transient (reflood 2 for Catawba / McGuire), as defined in 10 CFR 50.46(a)(3)(i). This is due to the combination of:

1 ) a change in Westinghouse fuel performance inputs from PAD 3.4 to PAD 4.0 (both PAD versions are approved by NRC), resulting in a PCT change of -75 OF for both reflood 1 and reflood 2, and

2) an error estimating the effect of TCD using a fuel performance model labeled 'PAD 4.0 +

TCD', which has not been approved by the NRC, with peaking factor burndown, resulting in a PCT change of +114 °F for reflood 1, and a PCT change of +15 OF for reflood 2 (limiting PCT).

The sum of the absolute value of these changes to PCT is greater than 50 OF, and is therefore considered to be significant. 10 CFR 50.46(a)(3)(ii) requires the licensee to provide a report within 30 days, including a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with 10 CFR 50.46. Duke Energy has reviewed the information provided by Westinghouse and determined that the adjusted BELOCA PCT values and the manner in which they were derived continue to conform to the requirements of 10 CFR 50.46. Duke Energy has evaluated the requirement for reanalysis specified in 10 CFR 50.46(a)(3)(ii) and proposes the following schedule for reanalysis.

Before December 15, 2016, Duke Energy will submit to the NRC for review and approval a LBLOCA analysis for Catawba and McGuire that apply NRC-approved fuel thermal performance methods which will include the effects of fuel pellet TCD. The date for the LBLOCA reanalysis submittal is contingent on the following licensing actions that are needed to perform a LBLOCA analysis with an NRC-approved ECCS Evaluation Model that explicitly models TCD, in compliance with 10 CFR 50.46(a)(1)(i):

1) Prior NRC approval of a fuel performance analysis methodology that includes the effects of fuel pellet TCD. The new fuel performance methodology would replace the current licensing basis methodology for Catawba / McGuire that is described in WCAP-1 2945-P-A for PAD 3.4, and WCAP-1 5063-P-A, Rev. 1 for PAD 4.0.
2) Prior NRC approval of a LBLOCA Evaluation Model that includes the effects of fuel pellet TCD, and accommodates the ongoing 10 CFR 50.46(c) rulemaking process. Per Reference 12, Catawba / McGuire are considered to be on implementation track number 2 for the 10 CFR 50.46(c) rulemaking, with compliance demonstrated no later than 48 months from the effective date of the rule. The new NRC-approved LBLOCA evaluation model would replace the current licensing basis methodology for Catawba / McGuire that is described in WCAP-12945-P-A, Volume 1, Rev. 2, and Volumes 2-5, Rev. 1.

This information satisfies the 30-day reporting requirement and required proposal for a reanalysis schedule as governed by 10 CFR 50.46(a)(3)(ii).

As part of the TCD assessment that was performed by Westinghouse for Catawba / McGuire, other 10 CFR 50.46 acceptance criteria were addressed in addition to PCT. Impacts to

U.S. Nuclear Regulatory Commission March 16, 2012 Page 2 of 5 Enclosure 2 maximum local oxidation, criteria (b)(2), maximum hydrogen generation, criteria (bX3), and coolable geometry, criteria (bX4) were also evaluated by Westinghouse for Catawba / McGuire, considering the effects of TCD.

Westinghouse confirmed that the current analysis of record results for maximum local oxidation, maximum hydrogen generation, and coolable geometry remain bounding, when the effects of TCD are considered [Reference 8]. The increased stored energy in the fuel due to higher fuel pellet temperatures with TCD is a short term effect that does not persist into the long-term cooling phase of ECCS performance evaluations. Therefore, impacts to long-term core cooling are considered insignificant when the effects of TCD are considered.

A summary of the PCT changes for McGuire Units 1 and 2 and Catawba Unit 1 and 2 are provided in the following Tables 4, 5, and 6.

U.S. Nuclear Regulatory Commission March 16, 2012 Page 3 of 5 Enclosure 2 Table 4 Peak Cladding Temperature Summary - McGuire Units 1 & 2 LBLOCA Cladding Temp Comments (OF)

Evaluation model: WCOBRA/TRAC, CQD 1996 MNS/CNS Analysis of record PCT (Reflood 2) 2028 Composite Model Prior errors (APCT)

1. Decay heat in Monte Carlo calculations 8 Reference A
2. MONTECF power uncertainty correction 20 Reference B
3. Safety Injection temperature range 59 Reference C
4. Input error resulting in an incomplete solution matrix 25 Reference D
5. Revised Blowdown Heatup Uncertainty Distribution 5 Reference E
6. Vessel Unheated Conductor Noding 0 Reference F Prior evaluation model changes (APCT)
1. Revised Algorithm for Average Fuel Temperature 0 Reference F Errors (APCT)
1. Thermal Conductivity Degradation with Peaking 15 Factor Burndown Evaluation model changes (APCT)
1. PAD 3.4 to PAD 4.0 -75
2. MUR Uprate to 101.7% of 3411 MWt 16
3. Peak FQ = 2.7 in bottom third of core 0 Absolute value of errors/changes for this report (APCT) 106 Net change in PCT for this report -44 Final PCT 2101 SBLOCA Evaluation model: NOTRUMP Analysis of record PCT 1323 2 inch break Prior errors (APCT)
1. None 0 Prior evaluation model changes (APCT)
1. None 0 Errors (APCT)
1. None 0 Evaluation model changes (APCT)
1. None 0 Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0 Final PCT 1323

U.S. Nuclear Regulatory Commission March 16, 2012 Page 4 of 5 Enclosure 2 Table 5 Peak Cladding Temperature Summary - Catawba Unit I LBLOCA Cladding Temp Comments (OF)

Evaluation model : WCOBRA/TRAC, CQD 1996 MNS/CNS Analysis of record PCT (Reflood 2) 2028 Composite Model Prior errors (APCT)

1. Decay heat in Monte Carlo calculations 8 Reference A
2. MONTECF power uncertainty correction 20 Reference B
3. Safety Injection temperature range 59 Reference C
4. Input error resulting in an incomplete solution matrix 25 Reference D
5. Revised Blowdown Heatup Uncertainty Distribution 5 Reference E
6. Vessel Unheated Conductor Noding 0 Reference F Prior evaluation model changes (APCT)
1. Revised Algorithm for Average Fuel Temperature 0 Reference F Errors (APCT)
1. Thermal Conductivity Degradation with Peaking 15 Factor Burndown Evaluation model changes (APCT)
1. PAD 3.4 to PAD 4.0 -75
2. Peak FQ = 2.7 in bottom third of core 0 Absolute value of errors/changes for this report (APCT) 90 Net change in PCT for this report -60 Final PCT 2085 SBLOCA Evaluation model: NOTRUMP Analysis of record PCT 1323 2 inch break Prior errors (APCT)
1. None 0 Prior evaluation model changes (APCT)
1. None 0 Errors (APCT)
1. None 0 Evaluation model changes (APCT)
1. None 0 Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0 Final PCT 1323

U.S. Nuclear Regulatory Commission March 16, 2012 Page 5 of 5 Enclosure 2 Table 6 Peak Cladding Temperature Summary - Catawba Unit 2 LBLOCA Cladding Temp Comments (OF)

Evaluation model: WCOBRA/TRAC, CQD 1996 MNS/CNS Analysis of record PCT (Reflood 2) 2028 Composite Model Prior errors (APCT)

1. Decay heat in Monte Carlo calculations 8 Reference A
2. MONTECF power uncertainty correction 20 Reference B
3. Safety Injection temperature range 59 Reference C
4. Input error resulting in an incomplete solution matrix 25 Reference D
5. Revised Blowdown Heatup Uncertainty Distribution 5 Reference E
6. Vessel Unheated Conductor Noding 0 Reference F Prior evaluation model changes (APCT)
1. Revised Algorithm for Average Fuel Temperature 0 Reference F Errors (APCT)
1. Thermal Conductivity Degradation with Peaking 15 Factor Burndown Evaluation model changes (APCT)
1. PAD 3.4 to PAD 4.0 -75
2. Peak FQ = 2.7 in bottom third of core 0 Absolute value of errors/changes for this report (APCT) 90 Net change in PCT for this report -60 Final PCT 2085 SBLOCA Evaluation model: NOTRUMP Analysis of record PCT 1243 4 inch break Prior errors (APCT)
1. None 0 Prior evaluation model changes (APCT)
1. None 0 Errors (APCT)
1. None 0 Evaluation model changes (APCT)
1. None 0 Absolute value of errors/changes for this report (APCT) 0 Net change in PCT for this report 0 Final PCT 1243

U.S. Nuclear Regulatory Commission March 16, 2012 Page 1 of 2 Enclosure 3 REFERENCES References for Tables 4, 5. and 6 A. Letter, M. S. Tuckman (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," May 3, 2001 B. Letter, M. S. Tuckman (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," April 3, 2002 C. Letter, W. R. McCollum, Jr. (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," July 29, 2003 D. Letter, W. R. McCollum, Jr. (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," May 26, 2004 E. Letter, J. R. Morris (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," June 21, 2005 F. Letter, T. C. Geer (Duke) to USNRC, "Report Pursuant to 10 CFR 50.46, Changes to or Errors in an ECCS Evaluation Model," March 13, 2007 References for Enclosures 1 and 2

1. NRC letter (M. Evans) to Duke Energy (J. R. Morris), "Catawba Nuclear Station, Units 1 and 2 - Information Request Pursuant to 10 CFR 50.54(f) Related to the Estimated Effect on Peak Cladding Temperature Resulting from Thermal Conductivity Degradation in the Westinghouse Furnished Realistic Emergency Core Cooling System Evaluation (TAC No. M99899)," February 16, 2012. [ADAMS Accession No. ML12044A018]
2. NRC letter (M. Evans) to Duke Energy (R. T. Repko), "McGuire Nuclear Station, Units 1 and 2 - Information Request Pursuant to 10 CFR 50.54(f) Related to the Estimated Effect on Peak Cladding Temperature Resulting from Thermal Conductivity Degradation in the Westinghouse Furnished Realistic Emergency Core Cooling System Evaluation (TAC No. M99899)," February 16, 2012. [ADAMS Accession No. ML12044A019]
3. Westinghouse letter from D. Warren to Duke Energy (Robert Harvey), DPC-1 0-21,

Subject:

Catawba and McGuire Nuclear Stations Transmittal of Duke LOCA Axial Power Shape, FAH, and PAD 4.0 Evaluations (Proprietary), dated May 19, 2010.

4. Duke Energy Letter from R. Repko to US NRC,

Subject:

McGuire Nuclear Station License Amendment Request for Measurement Uncertainty Recapture Power Uprate, dated March 5, 2012.

5. Westinghouse WCAP-12945-P-A, Volume 1, Rev. 2, and Volumes 2-5, Rev. 1 (Proprietary),

Code Qualification Document for Best Estimate LOCA Analysis, March 1998.

U.S. Nuclear Regulatory Commission March 16, 2012 Page 2 of 2 Enclosure 3

6. Westinghouse letter from J. A. Gresham to U.S. NRC, LTR-NRC-12-27,

Subject:

Westinghouse Input Supporting Licensee Response to NRC 10 CFR 50.54(f) Letter Regarding Nuclear Fuel Thermal Conductivity Degradation (Proprietary / Non-Proprietary),

dated March 7, 2012.

7. Westinghouse letter from C. Trunick to Duke Energy (S. Thomas), DPC-1 2-35,

Subject:

Information Regarding the McGuire Units 1 & 2 and Catawba Units 1 & 2 Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown Including Design Input Changes (Non-Proprietary), dated March 7, 2012.

8. Westinghouse letter from C. Trunick to Duke Energy (S. Thomas), DPC-12-36,

Subject:

Additional Information for Duke Energy Regarding the Evaluation of Pellet Thermal Conductivity Degradation (TCD) for McGuire Units 1 & 2 and Catawba Units 1 & 2 (Proprietary / Non-Proprietary), dated March 7, 2012.

9. NRC letter (S. Richards) to Westinghouse Electric Co. (H. A. Sepp), Safety Evaluation Related to Topical Report WCAP-1 5063, Revision 1, "Westinghouse Improved Performance Analysis and Design Model (PAD 4.0)" (TAC No. MA2086), dated April 24, 2000. [ADAMS Accession No. ML003706392]
10. Duke Energy Methodology Report DPC-NE-201 1-PA, Rev. la, Nuclear Design Methodology Report for Core Operating Limits of Westinghouse Reactors, June 2009.
11. Duke Energy Methodology Report DPC-NE-1005-PA, Rev. 1, Nuclear Design Methodology Using CASMO-4/SIMULATE-3 MOX, November 2008.
12. Preliminary Draft of Federal Register Notice on the 10 CFR 50.46c Performance-Based Emergency Core Cooling System (ECCS) Cladding Acceptance Criteria, January 10, 2012.

[ADAMS Accession No. ML12005A004]

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