An investigation of the strength of branch areas in the piping of nuclear power installations

A three-dimensional shell finite-element method and a computer code have been developed in RRC ‘Kurchatov Institute’ for the strength analysis of branch pipe (nozzle) areas, which are among the most critical as regards strength components of pipes in both reactors and other systems. According to the method, the structure under study is broken up into eight-node isoparametric shell-type finite elements, each with eight or 18 integration points. The program was tested with the help of experimental results. The strength analyses of equal and unequal T-pipes were performed. Consideration was given to the variants with loading by pressure and moments (symmetric and asymmetric cases). The effects of fillet wall thickness and radius on the stressed state of the T-pipes were investigated.