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), Ontario Hydro (now Ontario Power Generation) and the US Atomic Energy Commission (AEC), 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.