Radioactive waste is waste from various activities, including nuclear power plants, nuclear medicine, mining, nuclear weapons reprocessing and nuclear research, that is radioactive. Low-level radioactive waste, such as rags, gloves, paper, tools and clothing that have been exposed to radioactive materials, contains small amounts of mostly short-lived radioactivity. Intermediate-level radioactive waste contains higher levels of radioactivity and requires some shielding.
High-level radioactive waste includes spent (i.e., used up) uranium fuel that was used in a nuclear power reactor that is no longer used to generate electricity. It is highly radioactive and also hot, due to heat from its radioactive decay, and thus requires cooling and extensive shielding. The volume of such waste is continuing to increase rapidly as a result of the continued large-scale use of nuclear power and the difficulty of disposing of it.
Radioactive waste can be extremely hazardous for humans and other organisms because of the radioactive particles that it emits. Radiation exposure can cause cancer, genetic damage and birth defects, and death, depending on its intensity, the length of exposure, and the decay mechanism. Depending on the type of waste, this danger can persist for decades and even centuries and millennia into the future.
Although the currently used fission nuclear power can offer some advantages over other power sources, one of its biggest unsolved problems is the safe and economical disposal of its wastes. Because this is largely a very long-term situation, it has been common to ignore or minimize it when considering the construction of new nuclear power plants and to just assume, or pretend, that the problems will be solved in the next few years or decades. In the meantime, the amount of radioactive waste continues to grow rapidly year after year.
Various technologies have been developed to reduce the volume of nuclear waste. Depending on the type of waste, they can include burning, concentration of the most hazardous components, and recycling. Disposal methods for the most highly radioactive and long-lived wastes include encasing in concrete and stainless steel, converting into a highly stable glass, and burying deep underground in seemingly stable geological formations. However, all of these technologies have problems, including high costs and public resistance to storage and burial sites, and thus more and more waste continues to be stored temporarily adjacent to nuclear power facilities.
Moreover, keeping the waste secure will become increasingly difficult because of the extremely long time that some nuclear waste remains hazardous, the ever-increasing volume of such waste, and the growing geographical dispersal of nuclear facilities and their waste. Among the various types of dangers are leakage from improper storage and transportation, including into underground water supplies, scavenging by people unaware of or unconcerned about the extreme hazards, terrorism, and armed conflict.
Whenever any of these situations does occur, there is often no simple or inexpensive way to clean up the leaked or dispersed radioactive material. It can take years to ensure that a contaminated area is again safe to live in or even to visit, and, in the case of very serious accidents, it can take decades.