VIBRATION ANALYSIS OF CANDU FUEL BUNDLES DURING ON-SITE TRANSPORTATION

A CANDU nuclear generating station is currently evaluating the transportation of irradiated spentfuel bundles, stored in Dry Storage Containers, from the spent fuel bays to an on-site storage facility. It is a requirement that the fuel bundles be transported in such a way that future retrieval of intact fuel will be possible. The fuel bundles are seated on trays which support the ends of the bundle at the bearing pads. Since the fuel trays and fuel bundles are subjected to vibration during transportation, an analysis is carried out in order to assess the possible fatigue damage. A finite element model of a stack of twenty-five loaded trays is subjected to an acceleration power spectra equivalent to a transport truck travelling at 20 km/h on a good-conditioned road. The results indicate that the fuel trays do not experience nns g-loads greater than 1. Hence there is no separation of fuel trays. It is shown that the stresses in the trays are below the endurance limit for 304L Stainless Steel The largest accelerations occur at the interface between the two top trays in the stack. The acceleration trace at this location is used as input for the vibration analysis of the fuel bundle, and is applied at the three supporting bearing pads on the outer fuel pencils. The maximum stress results from the fuel bundle vibration analysis are used to predict the fatigue damage of the fuel bundle during transportation. It is shown that the fuel bundles do not experience fatigue failure when subjected to this level of vibration.