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.

Radon Gas

During uranium exploration and mining, huge quantities of Radon gas are released into the air and dissolved in surface waters. The US Surgeon General has determined that radon is the second leading cause of lung cancer after cigarette smoking. In fact, thousands of Canadians die every year from exposure to radon gas.

When Radon-222 gas is released from a uranium mine, it deposits solid radioactive dust on the ground for hundreds of miles downwind from the mine site. The Radon-222 and all of its radioactive decay chain products release twelve times as much radiation as is in the Uranium-238 itself. These solid particles that form when Radon-222 decays quickly become Lead-210, which has a half-life of 22.3 years. This results in radioactivity that will be measurable in the area for more than 100 years after the mine is closed.

Radioactivity

Radioactivity is commonly measured in becquels (Bq). This unit of measure is named for the French physicist, Henri Becquerel, who together with Marie Curie, pioneered research on radioactive elements and their decay. One Bq is equal to the decay of about one radioactive nucleus per second.

Because the level of radioactivity is directly related to the number and type of radioactive atoms present, radon and all other radioactive atoms are measured in becquels. For instance, a house having 200 becquels of radon per cubic meter of air (200 Bq/m3) has 200 atoms of radon decaying every second in every cubic meter of air inside the house. A 1,000-square-foot house with 200 Bq/m3 of radon has nearly 3 million radon atoms decaying in it every minute, each releasing ionizing radiation. The Canadian Radon Guideline recommends that, when 200 Bq/m3 is measured inside a home, the air should be ventilated to minimize the concentration.

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?

Uranium Enrichment for Reactors and/or Weapons
Uranium is generally used in reactors in the form of uranium dioxide (UO2) or uranium metal. Nuclear weapons use the metallic form. Production of uranium dioxide or metal requires chemical processing of yellowcake.

Present Canadian CANDU reactors were designated to use natural uranium, which is 99 percent Uranium-238. Most other reactor designs require higher percentages of Uranium-235 than are present in natural uranium, namely they use 3 to 5 percent Uranium-235. The process used to increase the concentration of Uranium-235 is known are uranium enrichment. More recently, CANDUs may be fueled with “slightly enriched” uranium (1 to 2 percent Uranium-235) to improve their economic efficiency. Nuclear weapons use “highly enriched” uranium, which is over 85 percent Uranium-235, although as low as 20 percent is considered “weapons-useable,” though with less reliability and effectiveness.

To enrich uranium, it must first be converted into the chemical form, uranium hexafluoride (UF6). Uranium hexafluoride is chemically toxic as well as radioactive. Also, it reacts with moisture, releasing highly toxic hydrofluoric acid.

After enrichment, UF6 is chemically converted into uranium dioxide or metal. The bulk of waste from the enrichment process is termed depleted uranium. It is depleted because most of the Uranium-235 has been extracted from it. Depleted uranium has been used by the United States military to fabricate armour-piercing conventional weapons and tank armour plating.

The enrichment process can also be reversed. Highly enriched uranium can be diluted or “blended down” with depleted, natural, or very low enriched uranium to produce 3 to 5 percent low-enriched reactor fuel.

Summary
The mining, processing and use of uranium produce large quantities of wastes, including the decay products Thorium-230 and Radium-226, which are hazardous for thousands of years.

Uranium waste rock and tailings storage sites have been identified as significant sources of radon gas released into the environment.

Open pit mines, mill waste rock and tailings infrastructures create large land footprints, that is, they physically take up a great deal of space. For example, the average surface lease agreement of eight mine sites in Canada is over 1,700 hectares per mine. Surface areas involved in lower grade ore deposits are even larger.

Uranium mining releases large amounts of radioactive radon gas, which is much heavier than air. The radon will follow the path of prevailing winds, depositing solid radioactive fallout (mainly radioactive lead and polonium). This natural pathway for water-borne and air-borne radioactive materials ends up in the food chain and in our drinking water. Such radioactive deposits pose a health risk to the population.

Prepared and endorsed by the Ottawa Coalition Against Uranium Mining (OCAMU), which is a group of Ottawa citizens acting to ensure the Ottawa water, air and surrounding ecosystem remain free of the byproducts of uranium mining. Uranium mining would poison these basic elements irreversibly. The goal of OCAMU is to raise awareness and request a moratorium on uranium mineral prospecting, exploration and mining in the Ottawa watershed.

ACT NOW

What you can do
Organize letter writing campaigns around potlucks or tea parties with friends and neighbours. Hand written letters are most effective.

Write your Member of Parliament and your member of the provincial legislature asking for a moratorium on exploration and development of uranium mines.

To find your MP’s contact information call 1-800-622-6232. To find your MPP’s contact information go to www.ontla.on.ca and click on Members and then MPP Addresses.

Write your city councilor and state how strongly you feel about having your city request the Ontario and Quebec Legislatures for a moratorium on uranium mineral prospecting, exploration and mining in the Ottawa watershed.

The Community Coalition Against Mining Uranium (CCAMA) has a website www.ccamu.ca. Under the “How You Can Help” tab, there is a “Letter Writing” sub tab.

Excerpts from this site on letter writing include:

* Explain that the proposed exploration site is at the headwaters of the Mississippi River watershed in Eastern Ontario, which provides drinking water to hundreds of thousands of people and is used for recreation and tourism.

* Explain that the site is in Algonquin territory, which was never surrendered or sold to the Crown.

* Call for a permanent moratorium of uranium mining in Ontario.

* Request that this issue be given top priority as Donna Dillman is on a hunger strike at the protest site since October 8th and we all would like to see her return home safely.