Posted by Guest Columnist on April 30th, 2010
Editor’s Note: This series of articles, “The Yellowcake Trail,” tracks all aspects of uranium in Canada from the mining and milling, to processing and use, throughout its eighty-year history. The series begins with the history of uranium in Canada.
At every stage in the nuclear chain, from extraction to processing and use, vast amounts of radioactive waste and other highly hazardous wastes are produced. Spills and leaks commonly occur, marking treacherous places in the yellowcake trail that remain deadly for hundreds of thousands of years.
Nuclear waste is the Achilles’ heel of the industry. The radioactive wastes resulting from mining and milling uranium are endemic, as is the nuclear waste (spent fuel) produced by reactors, which contains so many extremely dangerous radioisotopes, such as plutonium. There is no safe way to permanently store radioactive nuclear waste.
But mining and exploration for uranium are going on full steam ahead, and Bruce Power is marching westward, seeking opportunities in areas with better economies than a “have-not” Ontario.
Canada’s Uranium – A Travelogue
Canada’s uranium, as yellowcake and in other more purified forms.
From the mines and mills in Saskatchewan, casks of yellowcake are shipped about 3000 kilometres to Ontario.
The ore from the uranium mines is shipped by truck to the mills. Trucks bring the yellowcake from the mills to Saskatoon. The yellowcake travels most likely by truck from Saskatoon to the refinery in Blind River, Ontario. The Blind River refinery also gets shipments of yellowcake for processing from around the world. Most of the purified uranium is trucked from Blind River to Port Hope, 600 kilometres away. The rest is sent to the UK for enrichment. This is as much as we know.
Any road or rail travel must go through a number of towns en route. What emergency measures are in place in case of accidents or major spills? How is such transportation insured? To what degree are any incidents or accidents reported publicly? The trucks were on the way to the US enrichment plant in Kentucky.
On August 4, 2009, the Canadian Press reported an incident where two truckers were exposed to radiation in 2008 while hauling a radioactive device for six days across the country. Apparently, the device had not been securely locked in place before transit, causing it to shift from a shielded to an unshielded position en route. A preliminary investigation by the Canadian Nuclear Safety Commission (CNSC) found that the drivers received about 35% more radiation in their six-day trip than the regulated public dose limit for one full year.
How many more such incidents go unreported?
Churning Out the Yellowcake and the Waste
Mining and milling are at the forefront of the nuclear chain. As in any mining operation, they go hand-in-hand. Mining extracts the raw uranium ore from rock and milling processes the ore to produce yellowcake.
At the mill, usually located at or near mine sites, the ore is crushed, then treated with strong acids and other chemicals to selectively leach out the uranium from the ore and dry it to a fine sand-like powder, uranium oxide concentrate U3O8 – yellowcake (about 70% pure uranium). Finally, the yellowcake is packed into 55 US gallon steel drums, similar in size to oil barrels, each containing about 400 kilograms of yellowcake, ready to begin its long journey to be further refined.
Yellowcake is one product of the mills, the other is waste. Throughout all stages of processing, copious amounts of water are used, and numerous toxic chemicals used in processing are unleashed. Usually the liquid waste is about double the quantity of the solid waste. The leaching agent, typically sulphuric acid, extracts uranium from the ore and along with it, several other substances, including heavy metals, such as molybdenum, lead, arsenic, mercury, manganese and cadmium.
Since a relatively small fraction of uranium is actually contained in the ore, the rest of the ore is radioactive waste. The vast amounts of wastes, known as tailings, are discharged from the mills into ponds or piles nearby. The tailings contain all the original constituents of the ore, including long-living radionucleides, thorium-230 (half-life of 80,000 years) and radium-226 (half-life of 1600 years), which represent about 85% of the initial radioactivity of the ore. The tailings also contain about 5-10% of the uranium not extracted by the milling process.
The radium in waste rock and tailings continuously decays to the radioactive gas radon-222, which can readily escape from the interior of the tailings. Radon releases are a major hazard that continues after uranium mines and mills are shut down. Just to prevent seepage of radon gas from the interior of the tailings, the waste must be stabilized by at least two metres of cover soil. The mix of constituents in the tailings can undergo various reactions which contribute to additional hazards. The poisoning of fish and plants downstream from the mines and mills is due not only to radioactive substances that accumulate in the sediment but also to heavy metals and process chemicals, whose effects are noticed long before the effects of radioactivity.
From the Mills to Ontario… and Beyond
Because yellowcake is about 70% uranium, further processing is required to remove impurities before it can be used. From the mills in Saskatchewan, casks of yellowcake travel to Ontario, the only province in Canada where yellowcake is refined for further use.
Each load hauled by truck contains about 17 tonnes of yellowcake. Some of the yellowcake may also be shipped directly to the US and other locations overseas, but neither the destinations nor the means of transport are publicly known.
Anna Tilman has researched several toxic issues, especially mercury. She is a Board member of the International Institute of Concern for Public Health.
Read more:
http://www.ourbigearth.com/2010/04/30/shift-news-uranium-mining-in-canada-part-2/