| A nuclear reaction begins with a Neutron hitting a Uranium-235 atom. The Uranium atom splits resulting in, what are called, fission products, which include gamma rays, Neutrons and new elements such as Krypton-92 and Barium-141. A critical reaction is where three Neutrons hit three Uranium atoms resulting in the release of three more Neutrons, a one to one ration. A subcritical reaction is where three Neutrons hit three Uranium atoms resulting in the release of two or less Neutrons, a three to two ratio. A supercritical reaction is where three Neutrons hit three Uranium atoms resulting in the release of four or more Neutrons, a three to four ratio. When a Nuclear Reactor is starting up, a supercritical reaction is used until the maximum number of Neutrons are being released and then the reactor is maintained with a critical reaction. The reactor is shut down by inserting special rods and chemicals, which absorb Neutrons, resulting in a subcritical reaction. |
