Why can't used nuclear fuel rods be put back where they came from?

Answer 1

Uranium can be reused after the separation from the other products of the nuclear fission: uranium enriched with the isotope 235 as fissile material and depleted uranium (mainly the isotpoe 238) as fertile material.

Answer 2

New reactor fuel is uranium (oxide) which has had the U-235 isotope increased from 0.7 percent, which is how it now exists in nature on earth, to around 4 percent. The rest is non-fissile U-238. During reactor operation the U-235 is used up, and when the fuel is discharged it has fallen to somewhere near the natural percentage. At the same time during operation some of the U-238 is turned into plutonium by neutron capture. Pu-239 is the first isotope to be formed, and this is fissile so starts to contribute thermal energy to the reactor output. By the end of fuel life the fuel thermal output is partly from U-235 and partly from plutonium. It also contains highly active fission products, so it has to be stored under water for some time to allow the activity to decrease.

In the UK and France the fuel is then sent to a chemical processing plant where the uranium and plutonium can be separated. This is potentially a dangerous process and has to be designed and operated very carefully, but at the end depleted uranium and plutonium are available.

Technology has been developed to allow the mixing of plutonium with partly enriched uranium to form what is called Mixed Oxide Fuel (MOX) and this is now being produced in the UK and France.

In the US all spent fuel from commercial plants has been stored on site, and not processed at all. This has been justified I think on the basis that new fuel from freshly mined uranium is readily available and not expensive. There is also I believe a ban on transporting used fuel and processing it, placed by the Federal Government, so it's a political matter whether this policy will be changed in the future. See link below

Answer 3

no where thats why so shut up and dont ask another question ever again

Answer 4

because you cant