The fuel rods at all six reactors at the stricken Fukushima Daiichi complex contain plutonium - better known as fuel for nuclear weapons. While plutonium is more toxic than uranium, other radioactive elements leaking out are likely to be of greater danger to the general public.
Only 6% of the fuel rods at the plant's Unit 3 were a mixture of plutonium-239 and uranium-235 when first put into operation. The fuel in other reactors is only uranium, but even there, plutonium is created during the fission process.
This means the fuel in all of the stricken reactors and spent fuel pools contain plutonium. Plutonium is indeed nasty stuff, especially damaging to lungs and kidneys. It is also less stable than uranium and can more easily spark a dangerous nuclear chain reaction.
But plutonium, like uranium, is a heavy element that is not easily dispersed in the air. It is the other byproducts of nuclear power generation, such as radioactive forms of cesium and iodine, that are more prone to spread and cause widespread contamination.
Ed Lyman, a physicist, estimates the fuel in Unit 3 is 5% to 10% more dangerous than the fuel in the other crippled reactors. Still, it is very unlikely to become packed tightly enough to reach what is known as critical mass and start a chain reaction.
{{/usCountry}}Ed Lyman, a physicist, estimates the fuel in Unit 3 is 5% to 10% more dangerous than the fuel in the other crippled reactors. Still, it is very unlikely to become packed tightly enough to reach what is known as critical mass and start a chain reaction.
{{/usCountry}}The Fukushima Daiichi site has a considerable number of fuel rods on hand, according to information provided Thursday by Tokyo Electric Power Co, which owns the atomic complex: There are 3,400 tons of fuel in seven spent fuel pools within the six-reactor plant.
If plutonium did get out, it wouldn't disappear quickly. Plutonium-239 has a half-life of 25,000 years, meaning it takes that long to lose half of its radioactive potency.