nuclear

What does the layman know about nuclear power generation? Here's a wiki link to get a clearer picture. To derive nuclear energy, the nuclear fuel needs to be 'consumed' by fission or fusion to get nuclear energy. Fuel rods are the physical object of this nuclear fuel mixed with structural, neutron reflecting materials. Here's a link to explain what is nuclear fission. In short, it is a chain reaction where nucleus of atoms are split into smaller parts. Imagine 1 object knocks into another object and splits into 2, and the new 2 knocks into another 2 to produce 4 objects, and so on and so forth. In a nuclear plant, this chain reaction is at a controlled rate, while in a nuclear weapon, it is uncontrolled.

The most common fissile nuclear fuels are Uranium 235 (²³⁵U) and Plutonium 239 (²³⁹Pu). From the newspaper, we have read that fuel rods need to be kept cooled to prevent its uranium from heating up. When it is heated up, it emits radiation. Here is a link to Today's that describes the hazards of these elements. Note that Plutonium and Uranium are heavy elements that are not easily dispersed in air. It was stated that the other by products of nuclear power generation (radioactive cessasium and iodine) pose a higher danger  as these are more prone to be spread. These substances have half-life.

Half-life is how long the substance takes to decay or decrease by half. Take a look at the higher danger elements such as Iodine-131 and Cesium-137. Iodine-131 has a half-life of 8 days while Cesium-137 has a half-life of 30 years. The not so easily dispersed elements Plutonium-239 has a half-life of 25,000 years, and Uranium-235 has a half-life of 700 million years.