ML12024A391

CFR 50.46 30-day Report for Changes to the Emergency Core Cooling System Performance Analysis

ML12024A391
Person / Time
Site:	Calvert Cliffs
Issue date:	01/19/2012
From:	John Stanley Calvert Cliffs, Constellation Energy Group, EDF Group
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML12024A391 (3)

Text

VI Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 CENG.

a joint venture of 0% ConstellatIon tEnergy eDF CALVERT CLIFFS NUCLEAR POWER PLANT January 19, 2012 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Document Control Desk

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit No. 2; Docket No. 50-318 10 CFR 50.46 30-day Report for Changes to the Emergency Core Cooling System Performance Analysis This letter is submitted pursuant to 10 CFR 50.46(a)(3)(ii) to provide notification of a significant change to the peak cladding temperature analysis result for the small break loss-of-coolant accident (SB LOCA) analysis. Because the effect on the peak cladding temperature of the analysis error is greater than 50'F from the temperature calculated for the limiting transient using the last acceptable model, the analysis error qualifies as significant as defined in 10 CFR50.46(a)(3)(i) and, consequently, is provided in Attachment (1).

The results of the SB LOCA analysis conforms to the Emergency Core Cooling System acceptance criteria of 10 CFR 50.46(b). The analysis vendor, AREVA, informed Calvert Cliffs of an error in the approved methodology which results in this reportable condition on December 20, 2011. Attachment (1) contains the results of the change in the peak cladding temperature based on the analysis for Unit 2.

Should you have questions regarding this matter, please contact Mr. Douglas E. Lauver at (410) 495-5219.

Manager-Engineering Services JJS/PSF/bjd

Attachment:

(1) 10 CFR 50.46 - 30 Day Report cc: D. V. Pickett, NRC Resident Inspector, NRC W. M. Dean, NRC S. Gray, DNR

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IL ATTACHMENT (1) 10 CFR 50.46 - 30 DAY REPORT Calvert Cliffs Nuclear Power Plant, LLC January 19, 2012

ATTACHMENT (1) 10 CFR 50.46 - 30 DAY REPORT INTRODUCTION This letter is submitted pursuant to 10 CFR 50.46(a)(3)(ii) to provide notification of a significant change to the peak cladding temperature analysis result for the small break loss-of-coolant accident (SB LOCA) analyses. Because the effect on the peak cladding temperature of the analysis error is greater than 50'F from the temperature calculated for the limiting transients using the last acceptable model, the analysis error qualifies as significant as defined in 10 CFR 50.46(a)(3)(i) and, consequently, is provided below.

SB LOCA AREVA performed a complete SB LOCA analysis for Calvert Cliffs. The analysis was performed with the AREVA evaluation method approved in Reference 1. Subsequently, AREVA determined that an error existed in the analytical model for S-RELAP5.

Specifically, the Sleicher-Rouse heat transfer correlation is used in S-RELAP5 for predicting heat transfer to single-phase vapor. The error was the result of an incorrect translation of an ambiguous equation in the correlation. This resulted in a heat transfer enhancement between the wall and the coolant instead of the expected heat transfer degradation. Correction of this error resulted in an absolute change in peak clad temperature from the prior analysis of record of greater than 50'F. The peak clad temperature results are provided in Table 1.

Note that the Calvert Cliffs SB LOCA analysis of record has significant margin to the peak centerline temperature limit of 2200'F.

Table 1, Calvert Cliffs SB LOCA Peak Clad Temperature Analysis Results Peak Clad Delta Peak Clad Temperature, *F Temperature, VF AREVA Fuel Analysis of Record 1626 March 2011 S-RELAP5 Sleicher-

+69 12/20/2011 error Rouse correlation Total change +69 Total 1695 SCHEDULE The approved method for performing SB LOCA analyses is EMF-2328, Revision 0. AREVA is updating this topical report and expects to submit EMF-2328, Revision 0, Supplement 1 to the NRC in February 2012 with an expected NRC approval date of September 2012. The Calvert Cliffs SB LOCA could be reanalyzed following that approval with a target schedule approximately 6 months later.

REFERENCE

1. Letter from Mr. D. V. Pickett (NRC) to Mr. G. H. Gellrich (CCNPP), dated February 18, 2011, Amendment re: Transition from Westinghouse Nuclear Fuel to AREVA Nuclear Fuel (TAC Nos.

ME2831 and ME2832)

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