Analysis of whipping effect on high energy pipe in a nuclear power plant

Abstract

The sudden rupture and further whip of high energy pipe is one of the safety-related problems in nuclear power plants. It has been widely investigated by a large number of researchers. In this paper, the dynamical behaviour of a whipping high energy pipe under the assumption of postulated ruptures is investigated. For this reason, a three-dimensional finite element model of the piping and U-bolt restraint has been created and the theoretical behavior has been compared with experiments. Then, the variation tendency of the various mechanical property has been analyzed with the time lapse. Finally, results were obtained for the root-mean-square displacement and the maximum of restraint force from the variation of overhang length, friction coefficient and initial clearance. The result shows that the pipe oscillates with a small amplitude after impacting on the U-bolt restraint, the impact velocity increases suddenly to a maximum value and then decreases rapidly to zero, and the restraint force undergoes periodic oscillation. The maximum restraint force and the root-mean-square (RMS) displacement are influenced by the number of U-bolts, overhang length and initial clearance.