Noob questions regarding fusion and fission

[RADboy]

fission typically uses U-235 and fusion titrium- deuterium for their reactions. which is more easily obtained and more plentiful? also I've heard of a new fission fuel called thorium which has a radioactive half-life under a 10 years and is plentiful so, any info on this stuff will be appreciated.

regarding fusion... i know fission reactions release more energy per reaction because they're "stacked" with U-235 fuel. why isn't it possible to "stack" tritium-deuterium to achieve more output energy for a fusion reaction?

 

[Astronuc]

fission typically uses U-235 and fusion titrium- deuterium for their reactions. which is more easily obtained and more plentiful? also I've heard of a new fission fuel called thorium which has a radioactive half-life under a 10 years and is plentiful so, any info on this stuff will be appreciated.

regarding fusion... i know fission reactions release more energy per reaction because they're "stacked" with U-235 fuel. why isn't it possible to "stack" tritium-deuterium to achieve more output energy for a fusion reaction?

I'm not sure what one means by 'stacked'. Nuclear fission, which typically occurs in certain heavy nuclei, e.g., U²³⁴* (= U²³³+n), U²³⁶*(= U²³⁵+n), or Pu²⁴⁰* (= Pu²³⁹ + n), releases about 200 MeV of energy in the form of kinetic energy of two lighter nuclei, the fission products, gamma-rays, and subsequent decays of the fission products, which includes beta and gamma emission.

d+t => He⁴ + n + 17.6 MeV.

One cannot change d or t, otherwise they'd be different elements/isotopes.

d = deuteron, or nucleus of a deuterium atom, and t = triton or nucleus of tritium atoms, both isotopes of hydrogen. Deuterum occurs in small quantities naturally, and tritum less so. Otherwise, deuterium and tritium are produced by artifical (manmade) nuclear reactions.

Thorium and uranium are naturally found and relatively abundant, but they are not infinite.

Thorium 232 has a half-live in the billions of years, but to useful as a fuel source, it is generally necessary to convert it to U-233, the fissile U-isotope. This is done in a thermal or epithermal breeder reactor, as opposed to a fast reactor, which is used to convert U-238 to Pu-239/240/241.

Look here for some basic notes on fission and fusion.
http://hyperphysics.phy-astr.gsu.edu/Hbase/nucene/nucbin.html#c5

 

[RADboy]

thankyou 'll try reading up more before i ask questions

i remember reading somewhere that thorium had a much shorter radioactive length.
what i mean is it does not take as long for thorium to stop emitting dangerous levels of radiation. or maybe it was toxicity? i just remember everybody was really psyched about this stuff... i also thought it was much more plentiful than U-235 even if it isn't infinite

 

[Drakkith]

fission typically uses U-235 and fusion titrium- deuterium for their reactions. which is more easily obtained and more plentiful?

Tritium is effectively NOT found in nature in quantities sufficient enough to use as a fuel source. The reason is that tritium has a very short halflife of about 15 years I believe. It just doesn't build up on Earth because of this.

Deuterium however is a stable isotope of hydrogen and while it only makes up 0.0156% of all hydrogen in the Earth's oceans, there are sufficient quantaties available to theoretically power Earth via fusion for a long, long time. (Long long time.) <---That's a real scientific number, I assure you.

regarding fusion... i know fission reactions release more energy per reaction because they're "stacked" with U-235 fuel. why isn't it possible to "stack" tritium-deuterium to achieve more output energy for a fusion reaction?

As Astronuc pointed out, this is incorrect. Fission produces more energy per reaction because the necleus of those atoms are bulging with positively charged protons. When it fission and the nucleus splits, the combined repulsive force between the pieces generates much more energy than a single reaction of Fusion. HOWEVER, a fission reaction with Uranium involves 1 atom with an atomic mass of about 235-238. The combined mass of Dueterium and Tritium in one fusion reaction has an atomic mass of only 5. That's 47 times less mass involved per fusion reaction. (Even less if you use Deuterium-Deuterium fuel) So per nucleon, or mass, fusion releases much more energy than fission does.