High Quality Content by WIKIPEDIA articles! NRX was a heavy water moderated, light water cooled, nuclear research reactor at the Canadian Chalk River Laboratories, which came into operation in 1947 at a design power rating of 10 MW (thermal), increasing to 42 MW by 1954. At the time of its construction it was Canada`s most expensive science facility and the world`s most powerful nuclear research reactor. Although nuclear reactors would not generate electricity until 1951, NRX was remarkable both in terms of its heat output and the number of neutrons it generated. When a nuclear reactor is operating its nuclear chain reaction generates many billions of free neutrons, and in the late 1940s NRX was the most intense neutron source in the world. As a result it opened up whole new areas of science that had not been possible before: Radiation therapy for treating cancer, neutron scattering for researching advances in materials from steel to semiconductors, production of radioisotopes for medical purposes, and R D essential for the birth of nuclear power: generating electricity from a nuclear reaction.