Regarding the supply of Canadian uranium to the Manhattan Project in the 1940s, its important to understand that it was not uranium ore, but rather material refined at the Port Hope refinery in Ontario.
It also helps to know that the quantity involved was relatively small, compared to the other resources available to the US at the time.
While Canadian uranium supply to the U.S. Manhattan bomb project totalled 700 tons, the U.S. already had 1,200 tons from Belgian Congo in 1942 and a further 3,700 tons were delivered by the end of 1944, one year before the Hiroshima blast. The U.S. also produced 800 tons from its own sources by 1944, and in April of 1945 the U.S. got another 1,100 tons of Congo ore from a Strassfurt factory in defeated Germany, for a total of some 7,500 tons.
That makes the Canadian contribution some nine percent (if anyone is aware of the details on how this material was distributed & used within the Manhattan Project, please let me know).
An earlier post suggested that US U-metal production at the time may have been as high as 90 tons a month. That would imply seven years of operation, assuming all 7500 tons were converted to metal (which of course it wasn't -- some early reactors, including CP-1, used large quantities of UO2 in addition to metal, and lots (majority ?) of the uranium was also converted to Hex for use in enrichment plants).
As for any potential health impact in the Niagara region due to the Electromet plant, its useful to read about the Health Canada study in Port Hope, where ore refining actually took place, over many years:
June 17, 2002
STUDY SHOWS NO CANCER EFFECTS IN PORT HOPE
The Canadian Nuclear Safety Commission released a medical study on June 17 that found that overall cancer rates in Port Hope, Ontario were comparable to cancer rates throughout the province of Ontario.
The study was subjected to scientific and independent peer review before publication.
The study, carried out by Health Canada, reviewed the incidence of cancer, particularly those types of cancer most prone to radiation propagation, for the years 1956-1997. Its finding of no excess of cancer in Port Hope was consistent with earlier studies of the town.
Cancer studies have been of interest in the Port Hope and surrounding communities because of concerns regarding the long term presence of low level waste from the radium and uranium refineries dating back to the 1930s.
CNSC, 06/17/02
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Copies of the Port Hope Cancer effects report from Health Canada can be requested via phone or email from the CNSC at:
http://www.nuclearsafety.gc.ca/eng/media/press/news_release.cfm?news_release_id=36
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Also interesting is this editorial, from a local newspaper, published at the time of the release of the above study:
Radiation risk in Port Hope appears to be negligible
Port Hope Evening Guide Fri 05 Jul 2002
Brian Parr
Brian Parr is a member of the Evening Guide's Community Editorial Board. Columns from editorial board members appear every Friday.
The long-running debate over low-level radioactive waste would be redundant if all the facts were known.
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The Port Hope Area Initiative Workshop on "alternate means" on June 26 was well-attended, and discussion was lively, if not always positive. As is often the case, those who seemed least knowledgeable about health, physics and radiation issues were loudest in their opposition, although a small minority of informed people also elected to paint an alarmist picture.
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In Port Hope, there has been irresponsibility and carelessness in the past. On a tour of Cameco last year I saw photographs of handling methods for radium from the 1930s or 1940s that made me shudder, but today things are tightly controlled, and Cameco represents less of a hazard to the environment than many other industries whose activities are less closely monitored.
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How serious is the radiation problem in Port Hope? The clean-up criterion for gamma radiation is 100 microRoentgens/hour, approximating to 1 microSievert/hour. The Federal Assessment of Waste Sites (1994) lists gamma radiation levels of over 100 microRoentgens/hour at the Alexander Street ravine, in the Waterworks area and between the railway viaducts, and less than 100 microRoentgens/hour at the Fire Fighters Museum site. At the Pine Street extension site there is sufficient soil cover to shield direct gamma radiation and to prevent upward radon migration with the exception of one very small localize dare. The highest calculated annual radiation dose for normal usage at the clean-up sites was 48 microSieverts above background, in the area between the viaducts. This compares with the proposed allowable annual dose to the public from nuclear facilities of 1,000 microSieverts and normal exposure in Port Hope, which is about 1,700 microSieverts.
Statistically, it has been calculated that exposure to an additional 5 rem/year (50,000 microSieverts/year) for 30 years will reduce average life expectancy by 150 days. For comparison, smoking a pack of cigarettes a day will reduce average life expectancy by 2,370 days (6.5 years).
The risk from radiation in our town therefore appears to be negligible. This is supported by the Report on Cancer and General Mortality in Port Hope, 1956-1997, which confirms that cancer deaths in Port Hope are in line with provincial averages. The absence of excess leukemia rates in children reinforces this view, because risk coefficients for childhood leukemia are relatively high, making it an early indicator of problems.
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Jaro