NRC 2014-0012, Large Break Loss-of-Coolant Accident Margin Summary Sheet - 30-Day Report

Large Break Loss-of-Coolant Accident Margin Summary Sheet - 30-Day Report

ML14044A046
Person / Time
Site:	Point Beach
Issue date:	02/13/2014
From:	Millen M Point Beach
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC 2014-0012
Download: ML14044A046 (3)

Text

EXTera ENERGY&

POINT BEACH February 13, 2014 NRC 2014-0012 10 CFR 50.46(a)(3)(ii)

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units 1 and 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 Large Break Loss-of-Coolant Accident Margin Summary Sheet Day Report In accordance with 10CFR50.46(a)(3)(ii), NextEra Energy Point Beach (NextEra), LLC, is submitting this 30-day report for the Point Beach Nuclear Plant (PBNP) Units 1 and 2 for the emergency core cooling system (ECCS) analysis performed by Westinghouse Electric Company, LLC. The following 30-day report pertaining to the application of the Westinghouse large break loss of coolant accident (LBLOCA) evaluation model is provided pursuant to 10 CFR 50.46(a)(3)(ii).

The Enclosure describes the ECCS evaluation model changes and errors to the large break loss of coolant accident (LOCA). The Table provides the large break LOCA peak cladding temperatures margin summary.

This submittal contains no new commitments or revisions to existing commitments.

Very truly yours, NextEra Energy Point Beach, LLC

~~

Michael Millen Licensing Manager Point Beach Nuclear Plant Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241

ENCLOSURE NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Emergency core cooling system (ECCS) analyses for Point Beach Units 1 and 2 are performed by Westinghouse Electric Company, LLC. The following 30-day report pertaining to the application of the Westinghouse large break loss of coolant accident (LBLOCA) evaluation model is provided pursuant to 10 CFR 50.46(a)(3)(ii). A summary of the calculated peak cladding temperature (PCT) changes for LBLOCA is provided in the Table.

LARGE BREAK LOCA ECCS EVALUATION MODEL CHANGES AND ERRORS Error in Burst Strain Application in the HOTSPOT Code In the application of the burst strain in the HOTSPOT code, burst strain is incorrectly applied to the inner radius rather than the outer radius of the cladding, which impacts the resulting cladding geometry at the burst elevation after the burst occurs. Correction of this error results in thinner cladding at the burst location and more fuel relocation at the burst node, leading to an increase in the PCT at the burst node.

• The estimated impact of this error is +50 oF for Unit 1 and 0 oF for Unit 2.

Previous LBLOCA PCT changes are documented in Reference 3.1. Table 1 summarizes the estimated impact of the changes/errors on the Point Beach Units 1 and 2 LBLOCA PCT, along with the cumulative effect of absolute PCT changes for both Point Beach Units. The limiting LBLOCA PCT with the estimated effect of all the changes/errors is 2185 oF and 2056 oF for Units 1 and 2, respectively. With the impact of all changes/errors, Point Beach Units 1 and Unit 2 continue to comply with the 10 CFR 50.46 acceptance criterion for PCT of ~2200 °F.

Proposed Schedule The schedule for LBLOCA re-analyses is as provided previously in Reference 2.

References 1 NextEra Energy Point Beach, LLC letter to NRC, dated August 23, 2013, "Large Break Loss-of-Coolant Accident Margin Summary Sheet- 30-day Report" (ML13238A222).

2 NextEra Energy Point Beach, LLC letter to NRC, dated March 1, 2013, "Thermal Conductivity Degradation Impact on Large Break Loss of Coolant Accident Analyses with ASTRUM Response to Request for Additional Information" (ML13063A289)

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TABLE LARGE BREAK LOCA MARGIN

SUMMARY

SHEET- 30-DAY REPORT Plant Name: Point Beach Units 1 and 2 2115114 Utility Name: NextEra Energy Evaluation Model: Westinghouse Realistic Large Break LOCA Evaluation Model using ASTRUM.

Evaluation Model PCT (Unit 11Unit 2):

Absolute PCT Net PCT Effect Effect Unit 11Unit 2 Unit 11Unit 2 A Prior 10 CFR 50.46 Changes or Error ilPCT +160 OF I +246 OF 160 OF 1338 OF Corrections- up to Year 2013 B Prior 10 CFR 50.46 Changes or ilPCT ooF I ooF OoF I ooF Errors Corrections- Year 2014 c 10 CFR 50.46 Changes in Year 2014 ilPCT Since Item B HOTSPOT error in burst strain application +50 °F I 0 OF 50 OF I 0 OF D Absolute Sum of 10 CFR 50.46 ilPCT 210 °F 1338 °F Changes The sum of the PCT from the most recent analysis using an acceptable evaluation model and the estimates of PCT impact for changes and errors identified since this analysis Page 2 of 2