Nuclear Power Demonstration (or NPD) was the first Canadian nuclear power reactor, and the prototype for the CANDU reactor design. Built by Canadian General Electric (now GE Canada), in partnership with Atomic Energy of Canada Limited (AECL) and the Hydro Electric Power Commission of Ontario (later Ontario Hydro, now Ontario Power Generation) it consisted of a single 22 MWe pressurized heavy water reactor (PHWR) unit located in Rolphton, Ontario, not far from AECL's Chalk River Laboratories. NPD was owned by AECL and operated by Ontario Hydro. The NPD was the prototype and proving ground for research and development that led to commercial application of the CANDU system for generating electric power from a nuclear plant using natural uranium fuel, heavy water moderator and coolant in a pressure tube configuration with on-power refuelling. Description The NPD station was located on the west bank of the Ottawa River about upstream from the City of Ottawa. It was situated close by the AECL research establishment at Chalk River and the HEPC hydro generating station at Des Joachims, Ontario. It had a maximum continuous output of 22 MW(e), which gave a net station output of 19.5 MW(e). The reactor was fueled with of UO2 in the form of ceramic pellets sheathed in Zircaloy-2 tubes. The fuel was subdivided into nine bundles per channel, and fuel changing was designed to be carried out on power by remotely operated machines which push a fresh bundle in one end of the channel and remove the spent bundle from the other end, a design feature that carried through to the later CANDU products. The primary role of NPD was as a prototype for CANDU engineering. Over the years it served as a test bed for new fuels, materials, components, and instruments. Equally important, NPD was the training and simulation center for generations of Canadian and off-shore CANDU operations staff. This role began shortly after the start of operation, when a training program was set up by Ontario Hydro. History In December 1961, the major construction phase was concluded and system testing was in full swing. Criticality was first attained on April 11, 1962, and first steam of nuclear origin was produced on May 8. The first electrical power was fed to the system on June 4, and on June 28 first full-power generation of 20 MW(e) gross was attained. NPD began operation in 1962 and was operational until