Radioactive materials play an important role in our lives. Some of the electricity you use comes from a nuclear power plant which uses them. Radio-isotopes are used in many medical applications. But did you know that once used, radioactive substances must be disposed off carefully?
The dangers of radioactivity
Exposure to even low levels of radioactivity is harmful to health. It can make you nauseated and feel like vomiting. It might even give you persistent fever and fatigue. Long-term exposure to radiation causes radiation sickness. Your bone marrow is damaged and cannot produce red blood cells anymore, leading to anaemia. Further, there is a big risk that you might just get cancer.
People working in nuclear power plants follow very strict safety procedures. Radioactive fuel rods and the wastes from the reactors are handled remotely, using robots. The walls of the reactors are coated thickly with lead, which absorbs all radiation. Workers must wear protective suits all the time, and get regular health check-ups done. In hospitals that use radio-isotopes, similar safety procedures are followed.
Long-term exposure to radiation damages the bone marrow and it cannot produce red blood cells anymore.
Disposing radioactive wastes
When disposing nuclear wastes, the most important thing is that the materials should not be released into the environment. Apart from causing radiation sickness and cancer, radioactive substances stay for a long time in the environment, causing damage to plants and animals as well.
All radioactive wastes are first pre-processed into a form that is chemically inert and does not leak into the surroundings. This is often done by melting the waste together with broken glass, pouring into a thick steel canister, and sealing the canister. The molten waste is turned into glass (vitrification), and becomes water and air proof. The cylinder absorbs all radiation.
Radioactive wastes are classified into low level (LLW), high level (HLW) and transuranic (TRUW) wastes. LLW mostly consists of radio-isotopes discarded by hospitals, as well as leftovers from material used to prepare nuclear fuel. It emits little radiation. LLW canisters are disposed of by burial at designated LLW disposal sites.
HLW consists of spent nuclear fuel (SNF) as well as certain material used in making nuclear weapons. SNF is often reprocessed to be used a second time in reactors. HLW canisters are first stored deep underground or underwater for about 20 years in special spent fuel pools. During this time, they slowly lose their high radioactivity and become LLWs.
TRUWs are the most dangerous, as they come from concentrated radioactive materials used to make nuclear weapons. They are disposed of in tightly-controlled facilities, in lead-lined canisters (as lead absorbs more radiation than steel). The canisters are buried 3000 feet below the earth’s surface, in a special location which has a thick layer of salt. TRUWs will take about 10,000 years before they become LLWs.