The Fukushima Disaster
How it happened according to Austin
We all remember the nuclear meltdown at the nuclear plant in Fukushima last year right? Nuclear materials released into the atmosphere, whole sections of the city being evacuated, and even meat being called out of markets due to the radiated cows.
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Recent studies have even shown that the radioactive materials have blown all the way over to the shores of California. This will no doubt mutate the sea life and fish that will be eaten, infect us humans, and no doubt start the long awaited zombie apocalypse. While the undead are probably growing in number and forming an unstoppable army, I decided to take some free time in between stockpiling bacon and waiting for the downfall of humanity to explain how this event could have possibly occurred.
Before I can explain what went wrong, we need to know what goes on in nuclear plants, namely nuclear fission. Nuclear fission is the splitting of a nucleus into smaller fragments. The only known fissionable atoms are Uranium-235 and Plutonium-239. In this example, we're going to say that a group of uranium-235 is just sitting there, minding their own business when suddenly a slow moving neutron flies into the group. This neutron is absorbed by one of the uranium, raising its atomic mass to 236. Unfortunatly, by raising the atomic mass and throwing off the proton-to-neutron ratio, the atom has become very, very unstable. After shaking around for a bit it will finally erupt producing the following three things:
1. two similarly sized atoms like Krypton-91 and Barium-142
2. an unholy amount of energy
and 3. a few freely moving neutrons
The process looks something like this.
nuclear-energy-fission-300x171.jpg
The free moving neutrons can be absorbed by the neighboring uranium, creating a chain reaction and releasing a massive amount of energy. And when I say massive I mean massive. 1 kilogram of uranium-235 creates energy equal to about twenty- thousand tons of dynamite.
Now the smart people in labs can choose to have the chain reaction controlled or uncontrolled. You may know of the uncontrolled nuclear fission by this.
Atomic_Bomb.gif

The controlled fission is what is used in nuclear plants. Certain steps are taken so that there are only a few amounts of slow moving electrons that are absorbed to cause the fission so that it doesn't get out of control. Most of the energy produced in fission is heat so a coolant such as water is placed in the nuclear core to remove heat; the water is evaporated into steam by the heat and is driven through a turbine which generates the electricity that is produced in the plant. It is a very strict setup and any missing parts would be disastrous. Namely, if the coolant wasn't in the reactor core, the heat from the fissions would start to melt things and could cause mechanical failures. You can probably tell that this is where things started to go wrong down in Fukushima.


During the earthquake that shook Japan of March 11, the operational reactors were disconnected from the main power and had to rely on the emergency generator to maintain coolant distribution. But then the tsunami hit and the water flooded the emergency generator and the coolant pumps stopped working. Workers were unable to get in due to the flooding and earthquake damage and reactors 1,2, and 3 started to overheat and melt important machinery as the water level in the core reduced. Finally, in one last coup de grace, the reactors went into meltdown and the nuclear materials were scattered into the atmosphere. Food grown in the area was banned due to radioactive materials getting into the water and soil, multiple workers were exposed to dangerous amounts of radiation, and the materials traveled here to the states where they are bringing about the end of times. Most likely. Probably. Maybe.
That+s+fine+until+you+encounter+a+small+floating+group+of+_3d007d1dba5a3b55e9ed60800249271c.jpg
Now that the accident has been explained, I need to get back to building that bunker.
Austin, if said accident was to occur except worldwide rather than just in Japan, how would the life of humans be altered? What would the possibilty of the world recovering from that? -Brett
Chances are that the human population would be moved to pockets of unirradiated areas and those that were radiated would either die off due to radiation sickness or mutate and start to diverge off the evolutionary path of humans to better suit the enviornment. While the survival of humans wouldn't be for sure, life would still continue on earth just going along a different line of evolution. - Austin

Hey Austin, so apparently Japan is scared of a zombie apacolypse too because according to this article, they've shut all of their nuclear power plants down. -Maren
http://www.cnbc.com/id/47290577

Austin, you said that the only known fissionable atoms are Uranium-235 and Plutonium-239. Do these isotopes of these elements have any specific chemical properties that other elements do not that allow them to undergo nuclear fission? - Nishtha

The nuclear force saturates due to its short range, meaning that heavier nuclei have protons that don't attract each other via the nuclear force but still repel each other electrostatically. This is why heavier nuclei tend to have more neutrons in relation to the number of protons - the neutrons only attract. The binding energy per nucleon, a measure of how tightly a nucleus is bound, peaks at about 60 nucleons. (There's also a sharp peak at 4; the alpha particle, which is a He-4 nucleus, is very tightly bound) So light nuclei require energy to split apart and would release energy only if you can fuse them together. You might expect that anything heavier than 120 nucleons would fission, but these nuclei are still bound together, so the two parts you would get in fission aren't likely to fly apart. It's not until you get into the elements heavier than lead that you find nuclei whose binding energy per nucleon is low enough that the fission fragments could tunnel apart - Austin


Resources
http://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disaster
http://fukushimaupdate.com/
http://www.world-nuclear.org/info/fukushima_accident_inf129.html