Some effects of water flow on the behaviour and safety of PWR internals

The vibration effects are studied on a mockup, effected by the coolant flow on the reactor internals. The theoretical relations are given describing the response of the bodies of cylindrical shells to random excitation by the liquid flow. The mockups of the support cylinder for the WWER reactor core were exposed to excitation forces of a harmonic character. The measurements of the spectrum of the vibration eigenfrequency and the damping coefficient were carried out using the system with electromagnetic vibrators modified for the water medium and the system developed by Prodera Co. for observing the generalized coefficient of damping. The results of the computations and experiments on mockups for air and calm water are tabulated. (Oy)