Extension of the theory of vibrating plate-type nuclear reactor fuel elements

Abstract

The phenomenon of structural-coolant interaction is often observed in nuclear reactor plants. The moving coolant provides an almost inexhaustible supply of energy for the induction and sustaining of internal reactor vibrations. This, coupled with component designs unique to nuclear reactors, leads to the possibility of a myriad of vibration problems associated with control rod blades, fuel plates, fuel rods, thermal shields, and heat exchanger components. Of the areas cited above, the problems associated with vibration of fuel plates assembled in a unit (subassembly) have been observed and investigated because of the importance in maintaining fuel element integrity. This investigation extends the analysis of previous investigations in two major directions. First, since little attention has been given the response of the subassembly, a numerical model based on the method of characteristics was formulated to predict plate-coolant response during transients. Second, the stability analysis of previous investigations was extended to include several previously unconsidered effects. The effect on system stability of "second-order" terms as fluid compressibility, rotary inertia and shear deformation was determined. The importance of the internal plate dissipation model was determined, and the effect on stability of using a solid damping model for internal plate dissipation rather than the linear viscous damping model was determined. Finally, the stability analysis of previous investigations was extended to treat the fuel plate subassembly as a finite array of coupled plates rather than an infinite array of plates. ...