NL-12-1957, 10 CFR 50.46 ECCS Evaluation Model, Annual Report for 2011 and Significant Change/Error Report

10 CFR 50.46 ECCS Evaluation Model, Annual Report for 2011 and Significant Change/Error Report

ML12293A092
Person / Time
Site:	Vogtle
Issue date:	10/18/2012
From:	Ajluni M Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-12-1957
Download: ML12293A092 (10)

Text

Mark J. Ajluni, P.E. Southern Nuclear Nuclear Licensing Director Operating Company, Inc.

40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.7673 Fax 205 992.7885 SOUTHERN ' \ '

COMPANY October 18, 2012 Docket Nos.: 50-424 NL-12-1957 50-425 U. S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant 10 CFR 50.46 ECCS Evaluation Model Annual Report for 2011 and Significant Change/Error Report Ladies and Gentlemen:

In accordance with the requirements of 10 CFR 50.46(a)(3)(ii), Southern Nuclear Operating Company (SNC) is submitting the enclosed Vogtle Electric Generating Plant Units 1 & 2 (VEGP) emergency core cooling system (ECCS) evaluation model significant change/error report.

On September 20, 2012, SNC received notification from its fuel vendor, Westinghouse Electric Company LLC (Westinghouse), of a change/error report which included the estimated effect on the VEGP limiting ECCS analysis fuel peak cladding temperature (PCT) for the large-break loss-of-coolant accident (LBLOCA) evaluation model. The estimated effect of this change/error report has been added to the estimated effects of the changes/errors previously reported in the annual report. The resultant accumulation of the absolute magnitudes of the applicable change/error estimated effects is greater than 50°F. This accumulation constitutes a significant change/error requiring a 30 day report, which is provided in Enclosure 1. Details of this change/error report are provided in Enclosure 2.

The resulting VEGP PCT continues to meet the criterion of 10 CFR 50.46(b)(1)

(i.e., ~ 2200 OF) with sufficient margin such that no reanalysis is required .

The requirements of 10 CFR 50.46(a)(3)(ii) also include an annual report by licensees of changes to, or errors in, acceptable ECCS models that affect the temperature calculation and the estimated effect of changes or errors on the limiting ECCS analysis. Accordingly, Enclosure 1 also includes a summary of changes/errors for 2011 for both the VEGP LBLOCA and the VEGP small-break loss-of-coolant accident (SBLOCA).

U. S. Nuclear Commission NL-12-1957 Page 2 This letter contains no NRC commitments. If you any questions, please contact Ken McElroy (205) 992-7369.

Respectfully submitted, M. J. Ajluni Nuclear Licensing MJAlRMJ/lac

Enclosure:

1. Generating Plant 10 CFR 50.46 ECCS Evaluation Annual Report for 2011 & Change/Error

2. Evaluation of Fuel Thermal Conductivity and Peaking cc: Southern Nuclear Operating Company Mr. S. Kuczynski, Chairman, President &

Mr. D. Vice President & Nuclear Officer Mr. T. E. Tynan, President - Vogtle Mr. B. L. Ivey, Vice President - Regulatory Mr. B. J. Adams, Vice President - Fleet RType: CVC7000 Senior Project

...."".,,1"\ .. Resident Inspector

Vogtle Electric Generating Plant 10 CFR 50.46 ECCS Evaluation Model Annual Reports for 2011 and Signi'ficant Change/Error Report Enclosure 1 Electric Generating Annual Report for to NL-12-1957 Vogtle Electric Generating Plant 10 CFR 50.46 ECCS Evaluation Model Annual Report for 2011 & Significant Change/Error Report Vogtle Electric Generating Plant - Unit 1 BASH Large Break LOCA Evaluation Table 1-1a - Current Changes/Errors Estimated Description Effect (Ll PCT)

Westinghouse Notification Letter LTR-LlS-12-514 documents the effects of fuel pellet thermal conductivity degradation (TCD) and assembly power/peaking factor burndown in the Vogtle Units 1 and 2 Appendix K large-break loss-of-coolant accident (LBLOCA) analysis. The evaluation incorporated the approved loss of 22 coolant best estimate analysis of reflood transients (LOCBART)

Transient Extension Method (TEM). The effects of updates to the codes and methods (denoted as a "rebaseline" of the analysis of record (AOR)), combined with the effects of the combined pellet TCD and assembly power/peaking factor burndown, was 22°F.

Table 1-1 b - Summary of Changes/Errors (2011)

Estimated Description Effect (Ll PCT)

None affecting PCT N/A Table 1-1c - Cumulative Impact of Changes/Errors LljPCTI Description (OF)

• Changes/Errors Previously Reported (Reference 1) 40

• Summary of Changes/Errors (2011) (Reference 2) 0

• Current Changes/Errors (Reference 3) 22 Cumulative Total 62 E1-1

Enclosure to NL-12-1957 Vogtle Electric Generating Plant 10 CFR 50.46 ECCS Evaluation Model Significant VogUe Electric Generating Plant - Unit 1 Appendix K Small lOCA Table 1-1d - Summary of Changes/Errors (2011)

Estimated Description Effect (f1 PCT)

None affecting PCT N/A Table 1-1e - Cumulative Description

• Changes/Errors Previously Reported 1) o

• Changes/Errors 2011 o Cumulative 'Total I o E1

50.46 ECCS Evaluation Model Significant Change/Error Report Generating Plant Unit 2 Break lOCA Evaluation

- Current Changes/Errors Estimated Description Effect (Ll PCT)

Westinghouse Notification 4 documents of fuel pellet (TCD)

~C!c:,onr.h power/peaking Vogtle Units 1 and 2 Appendix K loss-of-coolant accident (LBLOCA) analysis. The evaluation incorporated the approved loss of 22 coolant best estimate analysis of reflood transients (LOCBART)

Transient Extension Method (TEM). The of updates to and methods (denoted as a "rebaseline" the analysis of record (AOR>>, combined with the effects of combined pellet assembly power/peaking factor was Table 1-2b - Summary of Changes/Errors (2011)

Estimated Description Effect (Ll PCT)

None ing PCT N/A Table 1-2c - Cumulative Impact of Changes/Errors

• Changes/Errors Previously Reported 40

• Summary of Changes/Errors (2011) (Reference o

• Changes/Errors (Reference 3) 22 Cumulative 62 E1-3 to NL-12-1 Vogtle Generating 10 50.46 ECCS Evaluation Model Significant Change/Error Report Vogtle Generating Plant - Unit 2 Appendix K Small Break LOCA Evaluation Table 1 - Summary of Changes/Errors (2011)

II lien"""",

Description Effect (t,. PCT)

None affecting PCT N/A Table - Cumulative Impact Changes/Errors t,.IPCTI Description (OF)

• Changes/Errors Previously Reported [R~ft:r t:r rl,;t: 1) 0

• Summary of Changes/Errors (2011) (Reference 0 Cumulative Total 0

-4 to 2-1957 Vogtle Electric Generating Plant 10 CFR ECCS Evaluation Model Significant Change/Error Report

References:

1. from Mark J. Ajluni to USNRC (NL-11-2402), "Edwin I. Hatch'll""""';""

Plant, M. Farley Nuclear Vogtle Electric Generating Plant 10 CFR 50.46 Evaluation Model Annual Reports for 2010," dated December 21,

2. Westinghouse Letter LTR-LlS-12-90, "A. W. Vogtle Units 1 and 10 CFR 50.46 Annual Notification and Reporting for 2011 ," dated February 22, 2 Westinghouse Notification Letter LTR-LlS-1 "Vogtle Units 1 and 2 10 CFR Notification and Reporting for Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown," dated September 2 E1-5

Vogtle Generating Plant 10 CFR 50.46 ECCS Evaluation Model Annual Reports for 2011 and Significant Report Enclosure 2 BASH-EM Evaluation of Pellet Thermal Conductivity Degradation and Peaking Factor Burndown to I\IL-12-1957 BASH-EM Evaluation of Fuel Pellet Thermal Conductivity Degradation and Peaking Factor Burndown

Background

Evaluations have been completed to estimate the effect of fuel pellet thermal conductivity degradation (TCD) on peak cladding temperature (PCT) for analyses using the 1981 Westinghouse large-break loss-of-coolant accident (LBLOCA) evaluation model with BASH [BART and System Hydraulics] (BASH-EM) with the loss of coolant best estimate analysis of reflood transients (LOCBART) Transient Extension Method. These evaluations utilized fuel rod performance input from a version of the Performance Analysis and Design (PAD) code that accounts for pellet TCD and that considered the beneficial effects of assembly power and peaking factor burndown resulting from the depletion of fissionable isotopes.

Affected Evaluation Model(s) 1981 Westinghouse Large-Break LOCA Evaluation Model with BASH Estimated Effect The estimated effect was determined on a plant-specific basis. The effects of updates to the codes and methods (denoted as a "rebaseline" of the analysis of record (AOR)) was 22°F, while the effects of the combined pellet TCD and assembly power/peaking factor burndown was OaF. The peaking factor burndown used in the evaluation is provided in Table 1; it is conservative for the current cycle and will be validated as part of the reload design process. SI\IC and Westinghouse utilize processes which ensure that the corresponding LOCA analysis input parameters conservatively bound the as-operated plant values.

Table 1: Peaking Factors Assumed in the Evaluation of TCD Rod Burnup FlIH (1 ,~) Fa (1)

(GWD/MTU) 0 1.65 2.50 30 1.65 2.50 60 1.40 2.00 62 1.40 2.00

1. Includes uncertainties

2. Hot assembly average power (P HA ) follows the same burndown since it is a function of FllH FlIH == l\Iuclear Enthalpy Rise Hot Channel Factor Fa  ::: Heat Flux Hot Channel Factor E2-1