Japan U-235

As most of the faithful readers here know, I’m not much good at prayer and mumbo-jumbo. I take great comfort in knowing the facts. Yep, there is nothing like having a solid grip on reality for me. So, I keep hearing about this nuclear cloud coming to our shores from Japan’s failed nuclear power plants. Not being very reassured by the governmental agencies reassurance that “everything is okay folks”. I decided to look into a few things myself. Of course, I only looked into the things that are so real that you could hit them with a hammer.

It seems that at least two of the power plants are under control because they are keeping them cool by pumping seawater into the reactor core. There is this little thing called “critical mass” that can cause uranium 235 fuel rods to burn ferociously when allowed to become too close together. They can keep the critical mass from being reached by keeping the fuel rods separated by “heavy water”. If anything happens to allow the rods to interact with each other and start ”reacting” they will melt down, hit the bottom of the reactor vessel, where they will start reacting uncontrollably. The Uraniun 235 reaction isn’t in danger of exploding because it isn’t contained tightly enough. (layman terms) It starts to heat up and burn uncontrollably, and melt through the bottom of the vessel. When that happens, the hot melting uranium will melt through the rock underneath and keep boring it’s way toward the center of the earth. Uranium 235 is heavier than the surrounding rock , so it will have a tendency to stay together and keep boring.

Eventually, the uranium will become diluted and lose it’s critical mass and stop heating. Unfortunately, while it is boring beneath the reactor vessel it will be spewing great masses of radioactive steam and other radioactive particles, that are very, very dangerous to breathe. Some people think that Iodine tablets may save them, but it’s not a very good cure for radioactive poisoning, in fact, there is speculation that it only works for children.

While it is comforting to know that the seawater that they are pumping will keep the reaction under control, it occurs to me to wonder what the next step will be. Those that think the problem will eventually go away are right, but the half life of uranium 235 is 700 million years! So, 700 million years from now, the uranium will be half gone. Sadly, the way half lives works, is that it will take another 700 million years to get rid of HALF the remaining u-235. That’s a long wait folks. I wonder how many times that they will be pumping the worlds supply of seawater past the reactor cores. Not a very comforting thought. Now I know why people just pray for miracles. It’s easier, and much more productive.