A small number of fission products
also have very long half-lives, notably technetium-99 (212,000 years) and iodine-129 (16 million years.
The criticality event tends to scatter the fissile material and fission products
in the area of the accident, and the dispersal of the fissile material normally prevents a prolonged chain reaction.
Inside these, spent nuclear fuel or solid uranium and fission products
would be stacked like poker chips within metal tubes.
In the latter the fission products
are invariably of telocentric appearance.
Development of Glass Compositions to Immobilize Alkali, Alkaline Earth, Lanthanide and Transition Metal Fission Products
from Nuclear Fuel Reprocessing
The prevention of risks to the general public will be studied by looking into the escape of radioactive materials including fission products
and heavy volatile elements as Po and Hg into the environment.
Calculations conducted at Oak Ridge National Laboratory showed that georeactor fission products
would include helium in precisely the range of compositions observed exiting Earth in volcanic lava.
Even though the plant is now shut down, fission products
such as uranium continue to generate heat, and therefore require cooling.
A modest fraction of radioactivity comes from fission products
that remain radioactive for decades, and a very small fraction from radioactive isotopes--primarily heavy elements such as plutonium created by neutron capture, as well as some of their radioactive decay products--that persist for tens to hundreds of millennia.
131]I), an isotope present in nuclear fission products
I participated in studies at Battelle in the 1970's that showed that the fuel can be reprocessed in such a way that the vast majority of the long-lived fission products
, including the transuranic materials, such as plutonium, can be recycled and successfully used as a new reactor fuel material.
In conventional reprocessing, uranium and plutonium are separated from the fission products
and other actinides in the spent fuel.