Given the concerns surrounding recent uranium exploration in Eastern Ontario and Western Quebec, this Fact Sheet is intended to serve as an educational document to put these activities in a wider context and to allow for greater transparency in the political decision-making process.
Uranium is widely found in trace quantities in rocks in Canada and elsewhere in the world. A few places, such as Australia and northern Saskatchewan, have large quantities of high grade uranium ore, that is, large amounts of rock with very high concentrations of uranium (as high as 20%). Uranium found in rock on both sides of the Ottawa River is somewhere between 0.1 and 0.2%.
Uranium as a pure element exists naturally in three forms: uranium-238, uranium-235, and uranium-234. Each of these forms, called isotopes, acts chemically similar for the most part, but has a different number of neutrons in the nucleus of the atom.
Uranium-235 and Plutonium-239 Fission
Besides emitting particles and transforming itself into a series of isotopes, uranium also has the ability to split itself into two lighter fragments when bombarded with neutrons. This splitting of the uranium atom releases energy. Uranium-235 can sustain a fission chain reaction, that is, enable split atoms to produce enough neutrons to trigger additional reactions so that this process is maintained without any external source of neutrons.
Uranium-238 cannot sustain a chain reaction, but it can be converted to Plutonium-239, which can. This ability to split atoms and release energy makes uranium important for nuclear weapons and nuclear power.
Health Risks
Uranium ore usually contains only a small percentage of pure uranium. As long as it remains outside the body, lower grades of this ore pose little health risk. However, if uranium is inhaled or ingested, its radioactivity can trigger the development of lung cancer and bone cancer. Rock and mineral collectors are generally urged to exercise extreme caution in handling, carrying and storing radioactive specimens, and to avoid letting children handle them.
Uranium at low concentrations is also chemically toxic and can cause damage to internal organs, notably the kidneys. The term cytotoxic refers to its ability to inhibit cell division. Animal studies suggest that uranium may affect reproduction and the developing fetus. The term tetratological refers to gross deformities in such infants. Its carcinogenic nature increases the risk of leukemia and soft tissue cancers, such as bowel cancer. Its mutagenic properties cause changes in the DNA genetic code and/or chromosomal damage.
Polonium-210 is the second last element in this decay series. It is also a left over from uranium mining. It is dumped into the tailing piles in quantities where its radioactivity is equal to that of uranium itself. The deadliness of Polonium-210 was revealed through the gruesome murder of Alexander Litvinenko in London, England in 2006. It is thousands of times more toxic than cyanide. It attaches itself to the red blood cells and
targets all the soft tissues of the body.
Uranium Exploration
Exploration includes activities such as clear cutting, surface stripping, trenching, drilling and blasting. The current Ontario Mining Act allows for surface stripping of large areas and the removal 1,000 tonnes of rock without requiring the mining company to restore the land. In Ontario exploration can begin with as little as 24 hours notice to landowners. After drilling, core samples are analyzed by geologists. It is worth noting that in the run-up to the 2007 provincial election, which Dalton McGuinty’s Liberal Party won, the Premier promised a full review of Ontario’s Mining Act.
In Quebec consent is required by the private landowner before exploration can proceed. If consent is not given, provision is given in the Mining Act for expropriation. The Ministry has verbally indicated that it will not support such expropriation procedures, however, this has not been tested in court.
Exploration of uranium can cause health risks to communities, especially those that already have high background levels of radiation. Taking rock samples can disturb uranium ore and release uranium into the biosphere. Once exposed to air and moisture, the composition changes – radioactive dust particles can spread by water and air. When drilling occurs, the exploration may disturb underground uranium deposits, which then can leach out into underground water reservoirs, potentially contaminating drinking water aquifers. At this point in time there is no requirement by federal or provincial legislation to monitor exploration for uranium in Ontario.
Mining, Milling and Refining
Crushing
Uranium ore is either dug out of the ground or the uranium is leached from the ore in the mine. Typically these mines are built to last in the order of 15 years. Drilling and blasting are used in either open pit (strip-mining) or underground mines. Because uranium is generally found in such low concentrations, huge amounts of rock must be mined. For every one tonne of uranium ore produced, there are 55 tonnes of tailings produced, when there is a concentration of 1.8 percent (1 tonne equals 1,000 kilograms). The uranium content of the ore is often between only 0.1 percent and 0.2 percent.
Before the uranium metal is extracted, the ore must be crushed into finer and finer fragments. After primary crushing, the ore is passed into a rotating ball mill, which grinds the rock into a fine powder. This powder is then treated to remove the uranium. The powder left over from the extraction of the uranium is called tailings. The minute size of these particles makes it impossible to keep them completely isolated from workers and the surrounding environment. In addition, the release of decay products of uranium into the biosphere is greatly accelerated.
While uranium deposits in Ontario generally have low concentrations of uranium, some of the ore bodies in Saskatchewan have more than 20 percent uranium. Lung cancer risks for miners in such ore bodies are so high that mining has been done by robots.
Milling
The ore is typically milled near the mine to reduce shipping costs. Huge amounts of water and chemicals are added to the pulverized ore. The uranium chemically bonds with a strong acid (sulfuric acid) or a strong base (caustic soda, also called sodium hydroxide) and, through a series of steps, about 90 percent of the uranium is separated from the host rock.
Refining
The last stage of drying, separating (centrifuging) and chemical precipitation, results in a product called yellowcake, which is a yellow to brown powder that contains 90 percent uranium oxide (U3O8). Once it is milled into yellowcake (U3O8), uranium in Canada is then sent to a refinery owned by Cameco Inc. at Blind River, Ontario, where it is further processed into uranium trioxide (UO3). The UO3 is then sent to Cameco’s Port Hope, Ontario facility, where it is processed into uranium hexafluoride (UF6) and uranium dioxide (UO2). The UF6 is treated to enrich the Uranium-235 to higher and higher concentrations. Uranium dioxide pellets are also made at a Zircatec plant at Port Hope for fuel rods for units of the Bruce nuclear power generating station. Uranium dioxide is also formed into pellets at the GE-Hitachi Nuclear Plant at 1025 Landsdowne Avenue in Toronto. These uranium dioxide pellets are then assembled into nuclear reactor fuel rods at Peterborough’s GE-Hitachi Nuclear Energy Canada Inc. facility.
Tailings Waste Tailings are the left-over sludge after the uranium metal is extracted from the uranium ore. The half-lives of the principal radioactive components of mill tailings, Thorium-230 and Radium-226 are long, 75,000 and 1,600 years respectively. These tailings are pumped into tailings ponds and covered with water to reduce radioactive emissions and to prevent oxidation of sulfide-bearing rock. Some tailings are covered in clay for long-term storage. The clay sill keeps oxygen out of the tailings and reduces the amount of ground water moving through the radioactive area. In addition to the radioactive hazards, tailings may contain chemically hazardous substances including cyanide, arsenic, lead and mercury, which are able to get into the environment by seepage, leaching and blown dust.
Uranium in eastern Ontario is estimated to be between 0.1 percent and 0.2 percent. This means that for every kilogram of eastern Ontario uranium oxide produced, about one million (1,000,000) kilograms of ground up rock will be dumped into manmade lakes, also called tailing ponds.
Occupational Health Hazards
Uranium mine workers are exposed to the highest radiation doses of any workers in the nuclear industry. The most serious health hazard associated with uranium mining is lung cancer due to inhaling uranium decay products. Uranium mill tailings contain radioactive materials, notably Radium-226 and heavy metals, for example, manganese and molybdenum, which can leach into the ground water.
According to the Ontario Workplace Safety and Insurance Act, “primary cancers of the trachea, bronchus and lung among workers previously exposed in uranium mining in Ontario are recognized as occupational diseases under the Workplace Safety and Insurance Act. They are characteristic of uranium mining and result from exposure to ionizing radiation relating to the uranium mining industry.”
It is fair to say that public health risks are greater with proximity to the mine and milling sites. However, those living downwind and/or downstream may directly be affected.
Waste Rock and Tailings Storage Sites
Uranium waste rock and tailings storage sites have been identified as significant sources of radon gas released into the environment.
Uranium tailings can retain as much as 85 percent or more of the original radiological elements.
Financial provisions for long-term funding of waste rock and tailings management are a concern. Bonds are usually posted by mining companies for long-term waste management, but are they sufficient for the duration of the hazard?
http://www.ccamu.ca/
