Miniature neutron source reactor(MNSR)is a typical pool-tank reactor,in which the natural convection is the major heat transfer method.In order to study the safety of MNSR,the transient thermal-hydraulic parameters under the rated power condition and accident condition were simulated.As to the rated power condition,the CFD software was used to conduct three-dimensional transient thermal-hydraulic numerical simulation while the RELAP5 code was used to calculate one-dimensional transient thermal-hydraulic par...