The Back End of the Nuclear Fuel Cycle

When the spent fuel is removed from the reactor, it is hot and very radioactive. It must be cooled and shielded from people. It is put into storage ponds at the reactor site. The storage ponds are steel-lined concrete tanks, about 8 metres deep and filled with water. The water cools the spent fuel rods and acts as a shield. The heat and radioactivity decrease over time - after about 40 years they are down to about 1/1000 of what they were when taken from the reactor. The longer they are stored, the easier they are to deal with.

Sometimes the spent fuel is sent off to plants in the United Kingdom and France for reprocessing. This means that the most highly radioactive waste, about 3%, is separated, concentrated and made into a special glass (vitrification). The unused uranium and some plutonium are then recycled into fresh reactor fuel. Plutonium is formed from the U-238 in the reactor core.

Spent fuel is generally treated as a waste and not reprocessed. After long storage in the ponds it can be put into a waste repository in a geologically stable area.

Greater technical detail can be found on this topic by searching through the listed briefing papers and education resources at www.uic.com.au.