ML063400346
| ML063400346 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/04/2006 |
| From: | Crouch W Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML063400346 (7) | |
Text
December 4, 2006 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
)
BROWNS FERRY NUCLEAR PLANT (BFN) - UNIT 1 TURBINE BUILDING SEISMIC RUGGEDNESS COMPLETION OF LICENSE CONDITION 2.C(15)
The purpose of this letter is to notify NRC that TVA has performed the necessary Unit 1 calculations which confirm the conclusions of the turbine building seismic ruggedness evaluation made in TVA's September 17, 2004, letter (Reference 1) in support of TVA's Alternative Source Term (AST) application. In a July 31, 2002 submittal (Reference 2), TVA requested an amendment to BFN Units 1, 2, and 3 that supported a full scope application of an Alternate Source Term (AST) methodology. In a September 27, 2004 (Reference 3) letter, NRC issued a Safety Evaluation (SE) approving implementation of a full AST for BFN Units 1, 2, and 3. The amendment modified the licensing and design basis to reflect the application of AST methodologies for Units 1, 2, and 3.
U.S. Nuclear regulatory Commission Page 2 December 4, 2006 As part of the approval of the AST license amendment, NRC requested that TVA confirm the seismic ruggedness of the Unit 1 turbine building and issued Unit 1 License Condition 2.C(15). This license condition was also referenced in NRC's September 27, 2006 (Reference 4), SE for the increased main steam isolation valve (MSIV) leakage License Amendment for Unit 1. The license condition states:
2.C(15)
The licensee is required to confirm that the conclusions made in TVA's letter dated September 17, 2004, for the turbine building remain acceptable using seismic demand accelerations based on dynamic seismic analysis prior to the restart of Unit 1.
In the September 27, 2006 letter, NRC stated that TVA must complete the actions necessary to establish the seismic ruggedness of the MSIV leakage alternative drain path for Unit 1 before the Unit 1 loss-of-coolant accident analysis becomes effective. In doing so, TVA is required to confirm the conclusions made in the September 17, 2004 (Reference 1), letter for the Turbine Building using dynamic seismic demand analysis prior to the restart of Unit 1.
TVA has performed the calculations that confirm the conclusions made in the September 17, 2004, letter. The calculation results, which are summarized below, are available for review at BFN:
The seismic II/I verification of the BFN Turbine Building, in support of the Unit 1 MSIV seismic ruggedness verification program and Amendment No. 261 for Unit 1 MSIV leak rate increases was performed based on approximate seismic spectral acceleration values for the Unit 1 Turbine Building. The evaluation (TVA calculation CDN0 303 2004 0233, "Seismic II/II Verification of Turbine Building") concluded that the Turbine Building would remain intact following a design basis earthquake (DBE).
Dynamic seismic analyses were performed for the Turbine Building (TVA Calculation CDN1 303 2006 0146, "Seismic Soil-Structure-Interaction Analysis of Turbine Building"). Detailed 3-dimensional (3D) SAP2000 finite element (FE) models were developed for the three parts of the Turbine Building addressed in the seismic II/I verification. Part 1 is the rectangular part adjacent to the Unit 1 Reactor Building. Part 2 is the Unit 1 turbine pedestal. Part 3 is the U-shaped portion of the building that surrounds the Unit 1 turbine pedestal. The 3D FE models include all of the major structural elements, i.e., walls, slabs, structural beams, and columns.
The detailed 3D FE models were used to develop a set of stick models to represent both the static and dynamic behavior for each of the 3 parts of the building. The stick models were then used for the DBE seismic response
U.S. Nuclear regulatory Commission Page 3 December 4, 2006 analyses, which included rigorous soil structure interaction (SSI) dynamic seismic analyses. Both best-estimate and upper-bound soil-property cases were investigated. The DBE ground motion time-history used as input for the dynamic seismic response analyses was the artificial acceleration time-history specified in the BFN seismic design criteria. Ground motion time history for the analysis of structures was previously reviewed and approved by NRC in the Section 2.2.1 of NUREG-1232 Volume 3, Supplement 1 SE (Reference 5).
The maximum horizontal seismic response accelerations were calculated at selected nodal points and compared with the acceleration values used in the previous seismic II/I verification of the Turbine Building as shown in the table below.
Maximum Acceleration (g)
(Envelope of E-W & N-S Directions)
Values Used in Previous II/I Analysis Best Estimate SSI Dynamic Analysis Upper Bound SSI Dynamic Analysis Portion of Building Elevation (ft)
(g)
(g)
(g) 632 0.48 0.17 0.34 617 0.48 0.17 0.34 586 0.48 0.17 0.30 Rectangular Portion at South End Lines J to M (Part 1) 563.5 0.32 0.16 0.24 617 0.32 0.16 0.27 Turbine Pedestal (Part 2) 555.5 0.32 0.19 0.26 680 1.01 N-S 0.68 E-W 0.17 0.28 617 0.48 0.20 0.28 604 0.48 0.20 0.28 586 0.48 0.20 0.28 Remaining U-Shaped Portion Lines A to H (Excluding Turbine Pedestal)
(Part 3) 555.5 0.32 0.16 0.24 In all cases, the dynamic seismic analysis results validate the previous seismic II/I verification of the BFN Turbine Building as follows:
Part-1 lower reinforced concrete frame and shear wall structure. The maximum DBE horizontal acceleration value from the dynamic response
U.S. Nuclear regulatory Commission Page 4 December 4, 2006 analysis ranges from 0.24g at grade level up to 0.34g at the operating deck elevation. The approximate value used in the previous II/I seismic verification of the building is 0.48g which is greater than 0.34g.
Therefore, the seismic verification for Part 1 of the building is conservative and valid.
Part-2 turbine pedestal. The maximum DBE horizontal acceleration value from the dynamic response analysis for the top of the Turbine pedestal is 0.27g. The approximate value used in the previous II/I seismic verification of the building is 0.32g which is greater than 0.27g.
Therefore, the seismic verification for Part 2 of the building is conservative and valid.
Part-3 steel superstructure. The maximum DBE horizontal acceleration value from the dynamic response analysis for the top of the roof of the Turbine Building is 0.28g. The approximate value used in the previous II/I seismic verification of the building is 0.68g in the east-west direction, and 1.01g in the north-south direction both are greater than 0.28g.
Therefore, the seismic verification for Part 3 of the building is conservative and valid.
In all cases, the conclusions made in TVAs letter dated September 17, 2004 (Reference 1) for the Turbine Building seismic II/I verification remain acceptable using the seismic demand accelerations. The results of the two calculations demonstrate the Unit 1 Turbine Building will remain intact following a DBE.
There are no new regulatory commitments contained within this submittal. If you have any questions, please telephone me at 256 729-2636. I declare under penalty of perjury that the foregoing is true and correct. Executed on this 4th day of December 2006.
Original signed by:
William D. Crouch Manager of Licensing and Industry Affairs
U.S. Nuclear regulatory Commission Page 5 December 4, 2006
References:
Plant - Units 1, 2, and 3 - response to Request for Additional Information (RAI) Related to Technical Specifications (TS) Change No. TS-405 -
Alternative Source Term (AST).
Units 1, 2, and 3 - License Amendment - Alternative Source Term.
- 3. NRC Letter to TVA dated September 27, 2004: Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Issuance of Amendments Regarding Full-Scope Implementation of Alternative Source Term.
- 4. NRC Letter to TVA dated September 27, 2006: Browns Ferry Nuclear Plant, Unit 1 - Issuance of Amendment Regarding Limits on Main Steam Isolation Valve Leakage.
- 5. NRC letter to TVA dated October 24, 1989: Supplement 1 to the Safety Evaluation Report on Browns Ferry Nuclear Performance Plan - NUREG -
1232, Volume 3.
cc: See page 6
U.S. Nuclear regulatory Commission Page 6 December 4, 2006 cc: State Health Officer Alabama Dept. of Public Health RSA Tower - Administration Suite 1552 P.O. Box 303017 Montgomery, AL 36130-3017 Ms. Eva A. Brown, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North (MS 08G9) 11555 Rockville Pike Rockville, Maryland 20852-2739 Ms. Margaret Chernoff, Senior Project Manager U.S. Nuclear Regulatory Commission (MS 08G9)
One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852-2739 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 Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611-6970
U.S. Nuclear regulatory Commission Page 7 December 4, 2006 DTL:SWA: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. G. Jones, POB 2C-BFN G. V. Little, NAB 1D-BFN R. A. DeLong, SAB 1A-BFN B. J. O'Grady, 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/alternate source seismic.doc