ML20198P407
| ML20198P407 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Oyster Creek |
| Issue date: | 01/23/1984 |
| From: | Turovlin B NRC |
| To: | NRC |
| Shared Package | |
| ML20151H203 | List:
|
| References | |
| FOIA-86-26 NUDOCS 8606060305 | |
| Download: ML20198P407 (3) | |
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3 RESPtNSE T4 NRC MEMS SF JULY 27. 1934 ATTAQMENT 1 e
1.
Convernence of the Solution The seismic response of rack F (Fig. 2.1 of the Licensing Report) has
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1 been studied using a series of time increments.
As susunarized in the FRC report (by R. C. Herrick, FRC Project C5506), the computed peak displacement of.843" (coefficient of friction.8. horizontal acceleration aligned with the narrow direction).00002 sec. time increment solution could not be further refined due to round-off errors.
To obtain the l
c'onverged value and to demonstrate convergence, Det ran the problem on a 4
14 degree-of-freedom model.
The results are summarized below.
1 Cat File No.
Time Step (sec)
Maximum Displacement (inch)
I DGPT60
.0003
.6631 DGPT61 0002 6631 DGPT62
.5991 6631 The successful convergence of the 14 D.0.F. model results is attributed to the elimination of rotary inertia terms from the equations of motion.
The equations of motion are deri.ved in the published paper,
" Seismic Response of Free Standing Fuel Rack Construction to 3-D Floor Motion", by A. I. Soler and K. P. Singh, Nuclear Engineering and Design, American Nuclear Society (c.1984).
I The displacements reported in the foregoing are upper bound solutions in view of tie fact that several simplifying assumptions, which render the i
analysis conservative, have been employed in obtaining the results.
Lower than permitted values of system damping, no credit for additional damping i
in the fuel assemblies, and synchronized impact of all fuel as=emblies in a module, are among the many assumptions which make the computed values t
i i
quite conservative.
2.
Equivalent Cap The licensee defers to the MAC position on the subject cf the use of the minimum gap, instead of the equivalent gap, in assessing the potential i
of inter-rack impact.
It is noted that the Commission's own guidelines provide for ar, Sit $$ combination of the computer Lak responses.
Therefore, the peak displacements of proximate' modules should be, combined by the SR$$ method and the resulting quantity compared with the available minimum cap.
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3.
Coupling Mass The fuel tassembly is modelled as a blunt square body inside a square cross section. container. The hydrodynamic coupling mass utilizes Fritz's well known correlations for infinitesimal motions.
Inclusion of finite amplitude motions.(which is the case for a rattling fuel assembly) is known to significantly reduce the peak rack seismic response (vide,
" Dynamic Coupling in a Closely Spaced Two Body System Vibrating in a Liquid Medium". by A. I. Soler and K. F. Singh, Proc. of the Third International Conference on Vibration in Nuclear Plant, Keswick, D.K.
1982). Therefore, Fritz's equation used in the analysis lead to an upper bound on the solution.
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