Original sentence: Medium and high level wastes are strong emitters of radiation and will require shielding for thousands of years
Edited sentence: Because nuclear fuels have more than a million times as much energy for a given weight, quantities of nuclear waste are more than a million times less than the chemical wastes produced by fossil fuel plants.Some regions, including France and Japan, reprocess them into fuel.The longest lived radioactive elements in these have a half life of roughly 30 years, and decay to levels below natural Uranium in 300 years.The other class of radioactive waste consists of fission products, essentially nuclear ashes.The unused fuels remaining in medium and high level wastes strongly emit radiation.When wasted, they require shielding for thousands of years