ML063110435

Report of Emergency Core Cooling System (ECCS) Evaluation Model Changes

ML063110435
Person / Time
Site:	Browns Ferry
Issue date:	11/07/2006
From:	Crouch W Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML063110435 (4)

Text

November 07, 2006 10 CFR 50.46 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop OWFN, P1-35 Washington, D. C. 20555-0001 Gentlemen:

In the Matter of

)

Docket Nos. 50-259 Tennessee Valley Authority )

50-260

)

50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - UNITS 1, 2, AND 3 - REPORT OF EMERGENCY CORE COOLING SYSTEM (ECCS) EVALUATION MODEL CHANGES The purpose of this letter is to report, in accordance with 10 CFR 50.46(a)(3)(ii), changes in the modeling used to determine compliance with ECCS requirements.

General Electric (GE) has recently provided TVA with an updated loss-of-coolant accident (LOCA) evaluation, which is associated with a sensitivity to the assumed axial power shape (top-peaked versus mid-peaked) for small break LOCA cases. For BFN, the GE evaluation affects the licensing basis peak clad temperature (PCT) for GE13 fuel. BFN Unit 1 will restart in Spring 2007 with a mixed core of GE13 and GE14 fuel. The current Unit 2 core also has GE13 fuel, although all GE13 fuel will be discharged during the upcoming Spring 2007 Unit 2 refuel outage. Unit 3 contains no GE13 fuel.

The estimated impact of the GE evaluation for GE13 fuel in terms of licensing basis PCT at a power level of 3458 megawatts thermal (MWt) and at 3952 MWt (Extended Power Uprate (EPU))

U.S. Nuclear Regulatory Commission Page 2 November 07, 2006 is presented in the below table. Changes from the previously reported GE13 licensing basis PCT values are shown in parentheses. The licensing basis PCT for GE14 fuel was not changed.

The AREVA ATRIUM-10 PCT analyses results provided in the table are based on EPU conditions (3952 MWt) and are bounding for operation at current licensed thermal power (3458 MWt) for Units 2 and 3. The small reduction in PCT for ATRIUM-10 (-5°F) fuel since the previous ECCS model report is a result of a correction of an error in bypass inlet reverse loss.

BFN continues to retain significant margin (nearly 200°F) to the maximum allowable PCT of 2200°F specified in 10 CFR 50.46(b)(1).

Peak Clad Temperatures for Fuel Types used at BFN Fuel Vendor BFN Unit Fuel Type PCT at 3458 MWt PCT at 3952 MWt GNF U1, U2 GE13 1845°F(+35°F) 1805°F(+25°F)

GNF U1, U2, U3 GE14 1760°F 1830°F AREVA U2, U3 ATRIUM-10 2002°F(-5°F)

No new regulatory commitments have been made in this submittal.

If you have any questions regarding this letter, please contact me at (256)729-2636.

Sincerely, William D. Crouch Manager of Licensing and Industry Affairs cc: See page 3

U.S. Nuclear Regulatory Commission Page 3 November 07, 2006 cc: State Health Officer Alabama State Department of Public Health RSA Tower - Administration Suite 1552 P.O. Box 303017 Montgomery, Alabama 36130-3017 U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-8931 Mr. Malcolm T. Widmann, Branch Chief U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-8931 NRC Unit 1 Restart Senior Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611-6970 Eva Brown, Project manager U.S. Nuclear Regulatory Commission (MS 08G9)

One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 Margaret Chernoff, Project Manager U.S. Nuclear Regulatory Commission (MS 08G9)

One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739

U.S. Nuclear Regulatory Commission Page 2 November 07, 2006 DTL:BCM:BAB cc: B. M. Aukland, POB 2C-BFN M. Bajestani, NAB 1A-BFN A. S. Bhatnagar, LP 6A-C R. H. Bryan, BR 4X-C R. A. DeLong, SAB 1A-BFN R. G. Jones, POB 2C-BFN G. V. Little, NAB 1D-BFN B. J. OGrady, PAB 1E-BFN K. W. Singer, LP 6A-C P. D. Swafford, LP 6A-C E. J. Vigluicci, WT 6A-K NSRB Support, LP 5M-C EDMS WT CA-K s:lic/submit/subs/November 2006 50.46 Letter