Nuclear Power Demonstration was the first Canadian nuclear power reactor, and the prototype for the CANDU reactor design. Built by Canadian General Electric, in partnership with Atomic Energy of Canada Limited (AECL) and the Hydro Electric Power Commission of Ontario 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.