BVY 05-061, Vermont Yankee Nuclear Power Station, Technical Specification Proposed Change No. 263 - Supplement No. 29 Extended Power Uprate - Steam Dryer Computational Fluid Dynamics

Vermont Yankee Nuclear Power Station, Technical Specification Proposed Change No. 263 - Supplement No. 29 Extended Power Uprate - Steam Dryer Computational Fluid Dynamics

ML051580370
Person / Time
Site:	Vermont Yankee
Issue date:	06/02/2005
From:	Thayer J Entergy Nuclear Northeast, Entergy Nuclear Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BVY 05-061, TAC MC0761
Download: ML051580370 (5)

Text

Entergy Nuclear Northeast Ank wm mm Entergy Nuclear Operations, Inc.

Vermont Yankee

= 11 tamp185 eg A--En y P.O.

Old Ferry Rd.

Box 500 Brattleboro, Vr 05302 Tel 802-257-5271 June 2, 2005 Docket No. 50-271 BVY 05-061 TAC No. MC0761 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Vermont Yankee Nuclear Power Station Technical Specification Proposed Change No. 263 - Supplement No. 29 Extended Power Uprate - Steam Dryer Computational Fluid Dynamics

References:

1) Entergy letter to U.S. Nuclear Regulatory Commission, "Vermont Yankee Nuclear Power Station, License No. DPR-28 (Docket No. 50-271), Technical Specification Proposed Change No. 263, Extended Power Uprate," BVY 03-80, September 10, 2003

2) Entergy letter to U.S. Nuclear Regulatory Commission, "Vermont Yankee Nuclear Power Station, License No. DPR-28 (Docket No. 50-271), Technical Specification Proposed Change No. 263, Supplement No. 26 - Steam Dryer Analyses and Monitoring," BVY 05-034, March 31, 2005 This letter provides additional information regarding the application by Entergy Nuclear Vermont Yankee, LLC and Entergy Nuclear Operations, Inc. (Entergy) for a license amendment (Reference 1) to increase the maximum authorized power level of the Vermont Yankee Nuclear Power Station (VYNPS) from 1593 megawatts thermal (MWt) to 1912 MWt.

In Reference 2, Entergy submitted the VYNPS steam dryer analysis, including an assessment of flow induced vibration derived by conservatively combining hydrodynamic loads with acoustic loads from the VYNPS acoustic circuit model. The basis for the hydrodynamic loads was a computational fluid dynamics (CFD) analysis performed at 100% of currently licensed thermal power (CLTP) and summarized in Reference 2.

The CFD analysis is a compressible large eddy simulation (LES) that is a state-of-the-art tool.

The CFD model provides additional insight into the fluid dynamics in the reactor dome. As requested by the staff, Attachment 1 to this letter provides the details of the CFD methodology used in the analysis of the VYNPS steam dryer. Attachment 1 contains additional analyses, beyond those reported in Reference 2, that were subsequently performed to simulate hydrodynamic loads at 120% of CLTP.

ALL' Ic~

BVY 05-061 Docket No. 50-271 Page 2 of 3 The following aspects of the analysis are noteworthy:

• Hydrodynamic pressure fluctuations on the steam dryer face adjacent to the steam nozzles have a frequency less than 30 Hz. Complex flow structures and vortices in the plenum near the main steam nozzles account for these pressure fluctuations.

. The CFD model time step and modeling parameters were developed to accurately simulate hydrodynamic effects. Because the LES simulation included compressibility, acoustic effects are also captured. It was found that pressure fluctuations with frequencies greater than 30 Hz are dominated by acoustic effects.

• A comparison of the CFD flow simulation for CLTP and extended power uprate (EPU) does not show significant changes in the flow characteristics or dryer loading that would structurally challenge the modified VYNPS dryer.

The results of the analyses performed to evaluate pressure loads on the steam dryer, together with steam dryer monitoring, provide reasonable assurance that the steam dryer will maintain its structural integrity at EPU conditions.

There are no new regulatory commitments contained in this submittal.

This supplement to the license amendment request provides additional information to clarify Entergy's application for a license amendment and does not change the scope or conclusions in the original application, nor does it change Entergy's determination of no significant hazards consideration.

If you have any questions or require additional information, please contact Mr. James DeVincentis at (802) 2584236.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on June __ , 2005.

Sincerely,

,May/K. 'hayer ite Vice President Vermont Yankee Nuclear Power Station Attachment (1) cc: (see next page)

BVY 05-061 Docket No. 50-271 Page 3of3 cc: Mr. Richard B. Ennis, Project Manager Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0 8 B1 Washington, DC 20555 Mr. Samuel J. Collins Regional Administrator, Region 1 U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406-1415 USNRC Resident Inspector Entergy Nuclear Vermont Yankee, LLC P.O. Box 157 Vernon, Vermont 05354 Mr. David O'Brien, Commissioner VT Department of Public Service 112 State Street - Drawer 20 Montpelier, Vermont 05620-2601

BVY 05-061 Docket No. 50-271 Attachment 1 Vermont Yankee Nuclear Power Station Proposed Technical Specification Change No. 263 - Supplement No. 29 Extended Power Uprate Steam Dryer Computational Fluid Dynamics Total number of pages in Attachment I (excludina this cover sheet) is 98.

BVY 05-061 Docket No. 50-271 EXTENDED POWER UPRATE VERMONT YANKEE NUCLEAR POWER STATION ACRONYMS Ap/DP differential pressure CFD computational fluid dynamics EPU extended power uprate FFT fast Fourier transform ITA iterative time-advancing LES large-eddy simulation NIST National Institute of Standards and Technology NITA non-iterative time advancing p pressure PSD power spectral density RANS Reynolds-averaged Navier-Stokes sg/SG strain gage UFD user-defined function URANS unsteady Reynolds-averaged Navier-Stokes VY Vermont Yankee Nuclear Power Station