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ObjectivesThis study explores the use of a nonlinear adaptive inertia weight particle swarm optimization (PSO) algorithm to realize the optimal design of the path and arrangement of pipelines in the nuclear power primary loop systems of ships. MethodsAccording to the pipeline layout design characteristics, the constraints, evaluation functions and spatial model of the primary loop system are established. Based on the number of pipeline nodes, a new fixed-length coding method for the PSO algorithm is proposed, along with a direction guidance mechanism. As the standard PSO algorithm has such shortcomings as a slow convergence speed and susceptibility to falling into the local optimal solution, an improved nonlinear adaptive inertia weight PSO algorithm supplemented by a linearly changing learning factor is proposed. The improved PSO algorithm is combined with a co-evolutionary algorithm to form a co-evolutionary PSO algorithm for solving branch pipeline problems. The improved algorithm is then applied to the pipeline layout optimization problem of the nuclear power primary loop systems of ships. ResultsThe simulation results show that the convergence speed of the proposed algorithm is increased by 40% –50% compared with that of the standard algorithm. The improved algorithm can not only obtain higher quality pipeline layouts, but also solve the problem in which the standard PSO algorithm can easily fall into the local optimal solution. Conclusions The results of this study can provide useful references for the pipeline layout optimization of the nuclear power primary loop systems of ships.

[Objectives] The purpose of this paper is to solve the main steam pipeline whipping protection problem from a ship's steam generator(SG) to the cabin wall.[Methods] Therefore, a finite element model of the inverted L-shaped pipeline and U-bolts is established using LS-DYNA software to simulate the collision dynamic process. Under two layout schemes,the stress-strain distribution and restraint rejection force time history curves of the U-bolts are analyzed.[Results] In collisions caused by the imaginary welding seam break of the SG oblique steam exit,the horizontal pipeline displacement is even greater than the vertical,requiring the installation of another group of U-bolts to restrain lateral pipeline movement. With regard to such limiting factors as cabin spatial dimensions and seam break collision protection for the right-angle elbow at both ends,one set of 45-degree obliquely installed U-bolts located at the inverted L-shaped pipeline elbow can replace two sets of horizontally and vertically installed U-bolts.[Conclusions] The results of this study can have guiding significance for the whipping protection design of the main nuclear power steam pipelines of ships.