[en] Despite the good performance of CANDU reactors to date, there is a need for more operating experience for some critical components. The importance of primary heavy water pumps has induced Ontario Hydro to construct a facility capable of testing the large pumps for the 750 MW reactors. The test loop is designed to accommodate pumps with motors up to 8952 kW, i.e., the Bruce pump size. Details are given of the initial test program, the test loop, and building. (U.K.)