Study On The Merging And Substitution Of Piping Specifications In The Design Stage Of Passive Nuclear Power Plants

Nuclear power piping commodity materials refer to the piping materials with characteristics of bulk commodity that used in the projects of nuclear plants.At the design stage of nuclear plants,the overall coordination of the selection of piping specifications could be carried out so that the reasonable design modification and commodity merging could be realized to reduce the number of purchase items,improving the efficiency of purchase works and brining convenience to the material management of the construction site.The 3D plant design software plays an important role in the merging and substitution of piping specifications.The background database of the software could be taken as the statistical data source of the of the amount of material usage,and the purchase amount precisely estimated from it could be used to form the feedback from purchase to the selection of specifications,helping to find the unreasonable selections and to raise the solutions of merging and substitution.On the basis of the CAP1400 nuclear plant project,this article analyses the method of selecting piping material specifications as well as the method of forming the purchase statistics in detail.It is found that those methods significantly impact the formation of purchase items,and the potential of merging and substitution of piping specifications exists.The reliability analysis model of nuclear plant pipes is built by combining the calculation formulas of nuclear plant pipes from ASME codes and the mature reliability analysis methods,and the quantitative index of assessing the design safety margins of the pipes is established.The example solutions of the merging and substitution of some part of piping specifications are raised by comprehensively considering the purchase amount estimations and the calculation results of reliability analysis.It is proved that the merging and substitution of piping specifications in the design stage of nuclear plants could be realized to help improving the efficiency of purchase and material management works.