Studies on the seismic buckling design guideline of FBR primary coolant systems. 1. Dynamic buckling experiments on liquid containing cantilever cylindrical shells under horizontal excitation

Dynamic bucking experiments on thin cylindrical shells placed inside a rigid liquid container were carried out using a shaking table. These shells and container represent the thermal baffles and the reactor vessel of a fast breeder reactor, respectively. The fluid pressure caused by the horizontal excitation distributes non-uniformly around the cylinders and causes external pressure buckling deformation on them. The buckling pressure was measured with various types of test cylinders under various seismic waves, and it was confirmed to be higher than that predicted by static buckling analyses. It was also found that sub-harmonic vibration occurs under a certain sinusoidal wave excitation and the response displacement increases suddenly at a lower pressure level than the buckling pressure obtained by seismic wave excitation tests. Based on the test results, it was pointed out that, in the seismic design to prevent the buckling of the thermal baffles the static buckling analyses can be used as long as the sub-harmonic vibration does not occur. (author)