ML20205A836
| ML20205A836 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 04/19/1985 |
| From: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| To: | John Miller Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8504260130 | |
| Download: ML20205A836 (1) | |
Text
BALTIM ORE GAS AND ELECTRIC CHARLES CENTER P. O. BOX 1476 BALTIMORE, MARYLAND 21203 ARTHUR E. LUNDVALL JR.
VICE PRESIDENT SUPPLY Director of Nuclear Reactor Regulation Attention: Mr. 3. R. Miller, Chief Operating Reactors Branch #3 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Calvert Cliffs Nuclear Power Plant Units Nos.1 & 2; Dockets Nos. 50-317 and 50-318 Damping Factors for Seismic Stress Analysis
Reference:
American Society of Mechanical Engineers ASME Code Case N-411 Gentlemen:
Baltimore Gas and Electric hereby requests permission to use the damping values given in the referenced code case. This code case applies to stress analysis for both operating basis and safe shutdown earthquakes, and approves the use of damping factors of five percent of critical damping up to 10 hertz, a linear decrease to two percent of critical damping at 20 hertz, and a constant two percent damping above 20 hertz.
This change would apply to all reanalyses and to the analyses of additional piping systems. It would result in a reduced number of supports, thus increasing piping flexibility and, usually, reducing thermal stresses. It is expected that the reduction in the number of supports will reduce the exposure accumulated by maintenance workers over the remaining operating life of the plant. We recognize that the elimination of some supports may increase the calculated movement of pipes, and we will ensure that such displacements do not cause adverse interaction with adjacent structures, components, and equipment.
Very truly yours,
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AEL/DTW/vf cc: D. A. Brune, Esq.
G. F. Trowbridge, Esq.
0gk Mr. D. H. Jaffe, NRC Mr. T. Foley, NRC 0
8504260130 850419 PDR ADOCK 05000317 p
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