The CANDU 600 Fuelling Machine is a complex mechanism which must run in safety conditions and with high reliability in the CANDU Reactor. The testing and commissioning process of this nuclear equipment meets the high standards of NPP’s requirements using special technological facilities, modern measurement instruments as well as appropriate IT resources for data acquisition and processing. The paper presents the experience of the Institute for Nuclear Research Piteşti, Romania, in testing CANDU 600 Fuelling Machines, including the implied facilities, and in development of four simulators: two dedicated to training the CANDU 600 Fuelling Machine Operators, and another two to simulate some process signals and actions.