Radioactive wave: Will tsunami lead to meltdown? What are fuel rods? These are long meta llic tubes conta in ing the uranium or plutonium fuel pellets that sustain the nuclear reaction these rods are loaded into the reactor core. In Fukushima the reactors use uranium oxide fuel pellets conta ined in zirconium alloy tubes Because they become so hot during nuclear fission, and because zirconium reacts th steam producing more heat fuel rods must be covered by a coolant such as ater or they may overheat. How is the reactor shut down? Control rods(of ten graph ite) are lowered into the reactor core beside the fuel rods Control rods are designed to absorb the neutrons generated by nuclear fission so that the chain reactions within the core can be slowed down or stopped When the March 11 earthquake struck control rods were automatically lowered into the Fukushima reactors, stopping the chain reactions What is a 'meltdown? If they are not covered by water the fuel rods will heat up because of the fission process. This heat can melt the fuel rods In Fukus hima the fuel rods were exposed to air because the water in the core boiled of f but more water couldnt be pumped in because of the pressure of the steam The rods heated up, and the zirconium casings were damaged because of the steam leaking radioactive gases and hydrogen. Hydrogen build-up almost certainly caused the explosions at the reactorsRadioactive wave: Will tsunami lead to meltdown? What are fuel rods? These are long metallic tubes containing the uranium or plutonium fuel pellets that sustain the nuclear reaction. These rods are loaded into the reactor core. In Fukushima the reactors use uranium oxide fuel pellets contained in zirconium alloy tubes. Because they become so hot during nuclear fission, and because zirconium reacts with steam producing more heat, fuel rods must be covered by a coolant such as water or they may overheat. How is the reactor shut down? Control rods (of ten graphite) are lowered into the reactor core beside the fuel rods. Control rods are designed to absorb the neutrons generated by nuclear fission so that the chain reactions within the core can be slowed down or stopped. When the March 11 earthquake struck, control rods were automatically lowered into the Fukushima reactors, stopping the chain reactions. What is a ‘meltdown’? If they are not covered by water the fuel rods will heat up because of the fission process. This heat can melt the fuel rods. In Fukushima the fuel rods were exposed to air because the water in the core boiled of f but more water couldn’t be pumped in because of the pressure of the steam. The rods heated up, and the zirconium casings were damaged because of the steam, leaking radioactive gases and hydrogen. Hydrogen build-up almost certainly caused the explosions at the reactors