1.  Nuclear fission occurs when the nucleus of an unstable uranium absorbs a slow moving         neutron and splits into two smaller nuclei, roughly equal in size and 2 or 3 neutrons.     2.  The neutrons released from a nuclear fission create a chain reaction, they are absorbed by         the unstable uranium and the process repeats itself as long as there are enough uranium atoms.                                                3. The missing words are:        The most common fuel used in a nuclear power station is uranium.        Chain reaction is controlled by the use of control rods.        The radioactive waste from nuclear power stations remain active for thousands of years.        A coolant takes heat away from the nuclear reactor to a boiler where steam is made.    4. Table about the disposal of different types of nuclear waste: Low level Intermediate level High level  Packed in drums  and dumped in a   lined landfill site.  Mixed with  concrete and  stored in stainless  steel containers.  Very difficult to  store as the  radiation damages  the container.