Skip to comments.Fantastic information on how nuclear reactors actually work and are fueled and maintained
Posted on 12/02/2011 10:08:30 AM PST by lefty-lie-spy
Nuclear reactors are powered by fuel containing fissile material. The fission process releases large amounts of useful energy and for this reason the fissioning components U-235 and/or Pu- 239 must be held in a robust physical form capable of enduring high operating temperatures and an intense radiation environment. Fuel structures need to maintain their shape and integrity over a period of several years within the reactor core, thereby preventing the leakage of fission products into the reactor coolant.
The standard fuel form comprises a column of ceramic pellets of uranium oxide, clad and sealed into zirconium alloy tubes. For light water reactor (LWR) fuel, the uranium is enriched to various levels up to about 4.8% U-235. Pressurised heavy water reactor (PHWR) fuel is usually unenriched natural uranium (0.7% U-235), although slightly-enriched uranium is also used.
The fabrication of fuel structures called assemblies or bundles is the last stage of the front end of the nuclear cycle shown in Figure 1. The process for uranium-plutonium mixed oxide (MOX) fuel fabrication is essentially the same notwithstanding some specific features associated with handling the plutonium component.
(Excerpt) Read more at world-nuclear.org ...
Thank you. I’ve seen this too. My knowledge of nuclear physics has grown 1000 times from what I used to know before our Fukushima incident. I was particularly interested in radioactivity of pellets and fuel bundles before fission and decay takes place, and what physical processes and nuclide creation occurs during a meltdown, and this information has been the best I’ve found in months. If you know of any similar scientific articles or papers, I would love to read them.
Bookmarked for my Physics classes.
For a bomb, you just take a sufficient amount of fissionable material and slam it together...and Kablooey.
For a nuclear reactor you have enough of this material in rods that are close enough together that they heat each other up. It is separated by carbon rods that prevent this process. The carbon rods are raised and lowered between the nuclear rods to increase or decrease the heat, making steam that turns a regular steam turbine.
In a ‘scram’ the carbon rods are lowered quickly to cut off the reaction.
The safety problems come from trying to get too much efficiency. A nuclear plant could be 100% safe if the material was NEVER close enough to heat up too much. But you would lose efficiency and not get all the heat you could.
There is a company in Texas that is making nuclear reactors small enough to power a small city. It comes in a fully contained box that you bury- when 20 years are up the fuel is spent and they dig up and replace the entire box.
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