ML19345C947
| ML19345C947 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 11/17/1980 |
| From: | Sylvia B VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 910, IEB-79-02, IEB-79-2, NUDOCS 8012080652 | |
| Download: ML19345C947 (3) | |
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kt-NOV 19 bou VrworxrA ELECTnIC AND Pownn COMPANY Excmnsow2),VamornzA 20261 November 17, 1980 Mr. James P. O'Reilly, Director Serial No. 910 Office of Nuclear Reactor Regulation N0/RMB U. S. Nuclear Regulatory Commission Docket,No. 5 38 r.
Region II Licensd No.
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g 101 Marietta Street, Suite 3100 E
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Atlanta, Georgia 30303 M
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Dear Mr. O'Reilly:
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WM REQUEST FOR ADDITIONAL INFORMATION E
F3 Ed NRC I.E. BULLETIN 79-02 5
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NORTH ANNA UNIT NO. 1 G)
This letter is written in response to your request for additional information concerning our reply to NRC I.E.
Bulletin 79-02, " Pipe Support Baseplate Designs Using Concrete Expansion Anchor Bolts" for North Anna Unit No. 1.
You requested that we provide a more complete description of the finite element modeling techniques used in the evaluation at North Anna along with sample calculations for typical baseplates.
As stated in our letter Serial No. 545 dated July 6,1979, Stone and Webster Engineering Document 11715 E&DCR P 1922 G, and supplement revisions were used as the basis for designing, reviewing, and modifying baseplates to assure baseplate flexibility was considered for determination of anchor bolt loads.
To determine curves and values used in E&DCR P 1922 G, a public domain program titled "ANSYS" developed by Swanson Analysis System, Inc. of Houston, Pa. was used.
A technical description of the finite element procedures utilized to develop the basis for the baseplate evaluation criteria is included in Attach-ment I to this letter.
The results of the "ANSYS" program were given in our letter Serial No. 545.
i Sample calculations for typical baseplates are being assembled and will be forwarded for your review by separate letter as soon as possible.
If you have any questions or require any additional information, please contact us.
Very truly yours,
,AD B. R,. Sylvia Manager - Nuclear Operations and Maintenance sav:SL1 cc:
Mr. Victor _Stello, Director Office of Inspection and Enforcement Washington, D. C.
20555 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation Washington, D. C. 20555 801208e
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Attechm nt 1 Overview of ANSYS*
The ANSYS (Engineering Analysis System ) computer program is a large scale general purpose structural program that utilizes finite element technology for the solution of several classes of engineering analysis problems.
ANSYS uses the matrix displacement method of analysis. The structure to be analyzed is mathematically modeled as a system of finite elements representing plate and spring segments interconnected at node points. Nodal degrees of freedom characterize the response of the structure. The interconnecting finite elements are assigned stiffnesses to represent those of the actual structure.
The ANSYS program uses the wave front or " frontal" direct solution method for solving the system of simultaneous linear equations developed by the matrix displacement method. A static analysis is L;ed to solve for forces, dis-placements, stresses, and strains in the structure under the action of applied loads.
- ANSYS Engineering Analysis System, by Swanson Analysis System, Elizabeth, Pennsylvania,1975 via Control Data Corporation, Waltham, Massachusetts.
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Finite Element Modeling Techniques' Finite element models were developed to simulate moment resistant baseplate behavior.
The baseplate is idealized as a mesh of plate elements connected at the corner nodal points. The concrete is represented by nonlinear spring elements attached to the nodal points and ground. These spring elements have the capability of resisting compressive forces only. Since the element cannot resist tension, the nodal points are free to translate in the +2 direction. Because of the nonlinear force displacement relationship, the analysis requires an iterative solution procedure. The ANSYS STIF 40 combination element was used for these springs. The same element type was used to represent the anchor bolts. In this case, however, the element is input such that it will resist tension only.
The ANSYS STIF 46 two-dimensional rectangular plate elements were used for the baseplate. This element has pure bending capabilities. The element has three degrees of freedom at each of the four nodal points:
one displacement normal to the plate and a rotation about each of the two orthogonal axes in the plane of the plate.
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