The second report was shorter. It recommended that Halban and Kowarski should move to the US where there were plans to make heavy water on a large scale. Plutonium might be more suitable than uranium-235, and plutonium research should continue in Britain. It concluded that the controlled fission of uranium could be used to generate heat energy for use in machines, and provide large quantities of radioisotopes which could be used as substitutes for radium. Heavy water or possibly graphite might serve as a moderator for the fast neutrons. In conclusion though, while the nuclear reactor had considerable promise for future peaceful uses, the committee felt that it was not worth considering during the present war.