Nuclear power is touted by many scientists as a clean sustainable energy source, but the waste produced by these nuclear power plants is hazardous to human health and the environment.
Several sources produce nuclear waste, including nuclear power plants. Production of new fuel cells also generates nuclear waste as does some medical, industrial and research activities.
Did you know? Nuclear power produces about 15 percent of Canada’s electricity. Currently there are 17 nuclear power reactors operating in Canada – one in Quebec, one in New Brunswick, and the rest in Ontario.
What’s the harm in nuclear waste?
Nuclear waste contains radioisotopes which are unstable configurations of elements that emit ionizing radiation as they decay and move towards stability (the point where they stop radiating). Common types of ionizing radiation are alpha, beta and gamma. While a sheet of paper can be used to block alpha particles, denser materials such as lead are required to block beta and gamma radiation.
An important property of a decaying radioactive material is the time it takes for this material to decay by half—this is called its half-life. Some materials such as lithium-8 (8Li) or nobelium-253 (253No) have half-lives of seconds or minutes; while others such as those in nuclear fuels have half-lives ranging from thousands to millions of years.
Did you know? Most nuclear waste comes from nuclear fuel that cannot be further used in a reactor to produce electricity.
The disposal challenge.
Nuclear waste can be divided into two categories based on its radioactivity: low-level and high-level. Low-level waste includes medical and research equipment such as gloves and lab coats used in the handling of radioactive materials. The risk to human health and the environment when disposing of these materials is considered low. This type of waste is typically burned and the ashes buried in special sites.
Did you know? Two common radioactive elements used in nuclear fuel are uranium 235 (235U) and plutonium 239 (239Pu). 235U has a half-life of 700 million years while 239Pu has a half-life of 24,200 years.
Disposal of high-level waste such as used fuel cells from a nuclear reactor pose a much more significant challenge. Most commonly, this nuclear waste is cooled in large pools and then encased in steel and concrete to shield the outside world from harmful radiation produced by the waste. These cases are then placed in long-term storage facilities.
Several countries including France, Sweden, and Finland are considering or already in the process of building long-term disposal facilities for nuclear waste. The design usually involves drilling a shaft, up to a kilometre in length, into a geologically stable formation (such as the Canadian Shield) and then depositing the cases into that shaft for long-term storage. This solution remains controversial as it doesn’t solve the waste problem, but merely forces current waste issues on future generations.
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Article first published October 22, 2011