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.
NRX was remarkable both in terms of its heat output and the number of free neutrons it generated. When a nuclear reactor such as NRX is operating, its nuclear chain reaction generates many free neutrons. In the late 1940s, NRX was the most intense neutron source in the world.
NRX and Zeep buildings 1945
Research reactors are nuclear fission-based nuclear reactors that serve primarily as a neutron source. They are also called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or maritime propulsion.
The CROCUS research reactor of the École polytechnique fédérale de Lausanne, in Switzerland.