31. Neutron temperature # Fast neutrons . talk ) 23 : 41, 25 April 2011 ( UTC) 32. We have international collaboration with other banana breeding centres where gamma rays and fast neutrons are used. 33. The plutonium-uranium ratio in the ash may even approximate the composition needed for fast neutron reactor fuel. 34. Finally, tritium and deuterium produces fast neutrons which means any reactor burning it would require heavy shielding. 35. This enables fast neutrons to dominate, which can effectively be used to constantly replenish the fuel supply. 36. When a fast neutron collides with a light nucleus, it loses a large fraction of its energy. 37. The cross section for interaction with nuclei is much larger for slow neutrons than for fast neutrons . 38. Fast neutrons are needed to make plutonium, the nuclear fuel that the breeder was meant to produce.39. In some designs, the coolant is the moderator and turns the useless fast neutrons into slow ones. 40. Moltex Energy based in the UK proposes to build a fast neutron reactor called the Stable Salt Reactor.