Oak Ridge National Laboratory was completed, later renamed to "Oak Ridge National Laboratory". The site was chosen for the X-10 Graphite Reactor, used to show that plutonium can be created from enriched uranium. Enrico Fermi and his colleagues developed the world's second self-sustaining nuclear reactor after Fermi's previous experiment, the Chicago Pile-1. The X-10 was the first reactor designed for continuous operation. After the end of World War II the demand for weapons-grade plutonium fell and the reactor and the laboratory's 1000 employees were no longer involved in nuclear weapons. Instead, it was used for scientific research. In 1946 the first medical isotopes were
R4 nuclear reactor R4 nuclear reactor R4 nuclear reactor was a nuclear reactor built at Marviken and the fourth nuclear reactor built in Sweden. It was heavy water moderated and intended for the dual role of 130MWe of power generation as well as plutonium production. It had a central role in the Swedish nuclear weapon programme. During the mid 1960s, the social democratic government officially abandoned the project of designing Swedish nuclear weapons and the Marviken-plant became derelict. It was never loaded with fuel, and the project was cancelled in 1970. The turbine hall was subsequently used for an oil-fired power station, and