Do fast breeders violates thermodynamic laws?

Question

Do fast breeders reactors violates thermodynamic laws?
It is said that they create more fuel than they use to start with, dosen't this violate the first rule saying energy and matter cannot be created and destroyed?

Answer 1

Of course not. Here's the deal. Natural uranium is mostly U-238 with a tiny bit of U-235. Enriched uranium has more U-235. U-235 has a higher cross section for neutron capture than U-238, so it is easier to get fission started with it. But ultimately, the U-238 has about the same amount of energy.

What a breeder reactor does is produce plutonium as a by-product of the reaction. You can mix that with natural (or even depleted) uranium to give you a usable fuel mixture. The reaction makes enough plutonium to replace what you used (or even more if you want some extra to make nukes out of). So effectively, the breeder reactor runs on sub-fuel-grade uranium. It doesn't violate conservation of energy--it just saves you the trouble of refining the uranium.

Answer 2

No. Natural Uranium is mostly U238 (238 neutrons and protons), but only U235 undergoes fission when impacted by a neutron, releasing more neutrons to make a chain reaction. U238 has a comparable energy content, but must be transmuted into Pu(something) by neutron absorption to become fissile. This normally only occurs to a small degree in reactors (from the fission neutrons). A breeder simply "bakes" U238 for a prolonged period with a U235 or Pu reactor to transmute a larger percentage.

Answer 3

No.

They do not create additional energy. They create additional fissile material in the form of plutonium. The energy released when plutonium undergoes fission comes from the binding energy in the nucleus.