how to ensure some idiot does not get hold of the spent fuel and make a dirty bomb
how to de commission the site when the reactor reaches end of life
This can vary depending on the type of material and its isotope. These are the largest problems presented with nuclear power.
1. Waste
Nuclear waste is usually a problem with conventional forms of power using radioactive materials. When you put these elements through nuclear fission, it results in one or more byproducts which may be environmental liabilities. Some of them have extremely long half lives and need to be properly contained (or in some cases, disposed of) which also leads to an extremely political problem with illegal dumping of these toxic substances. Another problem is that some of said materials / substances can be used in production of nuclear weapons.
2. Core Overload
When the material in a standard reactor is not cooled to a constant temperature capable of lowering the immense heat produced, it can result in the fissile material overheating and causing immense damage, perhaps in the form of an explosion. It would have devastating environmental implications, and one overload can have global effects.
Sounds like there is supposed to be a list to choose from, but I think everybody would agree that the longterm hazardous waste products are it. Used fuel rods, and chemicals; all needing secure storage.
Nuclear explosion I suppose.
