ZEEP

The ZEEP (Zero Energy Experimental Pile) reactor was a nuclear reactor built at the Chalk River Laboratories near Chalk River, Ontario, Canada (which superseded the Montreal Laboratory for nuclear research in Canada).

ZEEP was the first operational nuclear reactor outside the United States.

[1] The reactor was designed by Canadian, British and French scientists as a part of an effort to produce plutonium for nuclear weapons during World War II.

[1][3][4][5][6] ZEEP was used to test reactivity effects and other physics parameters needed for reactor development at Chalk River Laboratories, including fuel lattices for the NRU reactor situated next door.

Its basic design was used by many other countries in initiating their own nuclear research programs.