Originally posted by IncognitoGhostman
reply to post by Stunspot
Plus you gotta think that it's Plutonium that is releasing and it's range is 4x farther and it's effect on humans is 10x more hazardous.
Far worse when inhaled with usually between 20 and 60 percent depending upon such things as the size of the particles, is retained in the lung. The rest is eliminated from the body within several days. Of that which remains in the lungs, about half will be removed each year, some to be excreted, some to lodge in the lymph nodes, and a very small amount will be deposited in other organs, mainly bone.
You're completely right, but plutonium isn't what is being released, it's only the fuel.
Quick lesson for those willing to learn:
Plutonium is used as the fuel, as it is capable of undergoing Fission, the splitting of an atom when disrupted by a Neutron. When struck by a fast moving (or slow, I can't recall that bit) neutron, the energy in the Plutonium atom is disrupted and the opposing charges of the protons in the nucleus force the nucleus to split in to two separate elements, as well as a further 2-3 neutrons which can then strike more atoms and react again. When this happens, an incredible amount of energy is released, which is then used to heat water to steam, and turn generators.
But what of the Fission fragments from the splitting? These are random, and can become one of many elements, but are usually radioactive themselves. It's the fission fragments that made it out during the earlier explosions, which as far as I know was the scientists venting pressure in the cores. The plutonium is certain to stay in the reactor, as it has no way of escaping.
You may hear phrases such as sub-critical, critical or supercritical. If the reactor becomes Sub-critical, this means it is no longer functional and is not producing energy. Critical is what every reactor is always at, it is the stable state, and it produces a steady stream of energy and means that power can be produced.
Supercritical is the one to fear, as this means that every neutron released by a fission is going on to cause another. This would in turn cause a build-up of energy over a short period of time, followed by a rather large explosion. This is how a Nuke works.
Having said this, the shape of the plutonium is critical (no pun intended) to how it reacts. In a reactor, it is kept in thin sheets, so that only one neutron at a time is causing a fission and the other two are sent out the sides of the sheet, where they don't react with anything unless they hit another sheet. (Control rods stop this when lowered)
When kept in a sphere however, the probability of every neutron hitting an atom becomes incredible, as it can go in any direction and still cause a fission, the amount of energy tripling each time (1 reaction releases 3 neutrons, those 3 cause 3 more fissions, which each release their own 3 etc). Essentially, if you have a large chunk of Plutonium, it'll blow up at some point.
The lowering of the control rods greatly reduces the energy produced, as they stop the stray neutrons from creating more energy. The problem in Japan is that the flow of the coolant stopped due to the power outage and the backup generators not working, this means that the energy has no escape and is heating up which, left unchecked, could result in what is called a 'meltdown', which is when the metal shielding around the core melts away due to the heat, providing less protection against the radioactive core and fission fragments.
The point is that the reactors aren't something to fear unless some idiot goes and builds one on a fault line. They can't explode like a nuke does, but they do remain dangerous to the immediate area for a long time if they go into meltdown. Chernobyl is only now dropping to levels that could be called safe, but the rest of the world is fine.
Admittedly, I'm not an expert, but this is how it works in basic terms. Hopefully I helped and didn't just scare more people.
edit on 1/4/2011 by roswell1 because: Clarity.