Nuclear grade pump qualification test loop system

The invention relates to a nuclear grade pump qualification test loop system. The loop system mainly consists of a main test loop section and a water charging system, wherein the main test loop section comprises a test pump, an extension-type cooler, pipeline exterior electrical heaters, a water storage tank provided with an electrical heating element, a pressure stabilizing tank, a venturimeter, two electric ball valves QV2 and QV3, an electrical control ball valve BV1 and a tee coupling pneumatic ball valve TV1; and the water charging system is composed of a water replenishing pipe, and the water replenishing pipe is divided into three branches which are connected with the test pump, the inlet of a circulating pump and the bottom of the pressure stabilizing tank. In the loop system provided by the invention, the main test loop and a heating cycle loop are matched together so as to finish the performance test, thermal shock test, impurity test and long duration test of the test pump, thereby realizing the localization of nuclear grade pumps.