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Sources of Contamination

During the years of plutonium production at Hanford from World War II until the early 1970s three different kinds of pollutants were discharged into the Columbia River: heat, chemicals and radioactive materials. There were five different radionuclides that contributed the most to the contamination of the Columbia River. These were phosphorus-32, zinc-65, arsenic-76, neptunium-239 and sodium-24. While there were other radioactive materials released into the river, it is estimated that these five radionuclides accounted for more than 94 percent of the contamination.

The routine operations of Hanford's first eight plutonium reactors were the main cause of the radioactive contamination of the Columbia River. The first three were built as part of the Manhattan project during World War II. The process of creating plutonium in theses reactors produced large amounts of heat. Water from the Columbia River was used in the cooling system. After it ran through the pipes in the core of the rector it was sent back into the Columbia. The intense radiation field of the reactor core caused chemicals in the water to become radioactive. Some of these chemicals were natural and others were added to clean the cooling system pipes. After leaving the core, the cooling water was near 2000 degrees F. To allow time for it to cool off it went into retention basins. This also allowed for short lived radiation to decay. The water was in the retention basins for two to six hours before being discharged back into the Columbia River.

Between 1949 and 1955, five more reactors were constructed at Hanford. In addition, the power levels were increased on all eight of the reactors to provide more plutonium for the country's nuclear arsenal during the Cold War. This required a significant increase in the amount of cooling water. The greater flow of cooling water reduced the time it spent in the retention basins down to as short as 20 minutes. Since the retention time was shorter the amount of radioactivity that was still present in the water when it went back into the Columbia increased. The Columbia River contamination levels were highest from 1957 to 1964. The ninth reactor built at Hanford, also the last, had a different cooling system. The N Reactor had two cooling systems and was designed so that the cooling water exposed inside the reactor was not released back into the Columbia but instead went to trenches along the banks.

Besides the cooling waters, fuel element failures and reactor purges contributed to the radioactive contamination of the Columbia River. Hanford's nuclear fuel was made up of fuel elements which were less than two feet long and encased in metal. Each reactor had thousands of fuel elements. When there was an increase in power levels more stress was put on the fuel elements. This caused splits to occur in the metal covering which allowed small chunks of radioactive fuel to be discharged into the river with the cooling water. The largest of these chunks weighed more than a pound. Hanford experienced almost 2,000 of these fuel element failures.

Contamination of the Columbia was also caused by purging the reactor piping. The water used to cool the reactors contained impurities. This caused a radioactive film to build up inside the cooling pipes within the reactor. This build up increased the radiation exposure to the workers in the reactor buildings. The piping system was routinely flushed with chemicals to remove the film, a process known as a reactor purge. When these reactor purges would occur, the radioactive film went through the retention basins and then into the Columbia River.

Roots of Exposure

People could have been exposed to the radiation from the Columbia River if they drank contaminated water, ate contaminated food such as fish, shellfish and waterfowl, or spent time along the shoreline or swam in the contaminated stretches of the Columbia River.

A person would have received the highest exposure from drinking contaminated water. People who drank from the Columbia River downstream from Hanford would have been exposed to radiation. The city of Richland originally used the Yakima River as a water source, but began using the Columbia in October 1963. Some people drank untreated water f,rom the Columbia. It was common practice for workers on barges to drop a bucket into the river to get their drinking water. In 1956, Hanford officials aware of the river's contamination considered issuing warnings about drinking untreated water from the river. They decided that restrictions were not essential and it might cause public relations to suffer.

The consumption of contaminated food was another source of exposure from the radiation of the Columbia. The fish of the Columbia River were contaminated. The radiation in the Columbia reached the Pacific Ocean and contaminated shellfish along the Washington and Oregon Coasts. Beginning in 1959 the levels of zinc-65 were monitored in the oysters of Willapa Bay. In 1959, the levels of zinc-65 were over 300 times higher the levels in oysters from the Japanese or Atlantic coasts. Ducks and geese that nested or fed along the Columbia River became contaminated. Waterfowl became radioactive from Hanford's waste ponds. In the early 1970's, ducks collected from the waste ponds near the reactors were found to have high levels of radiation. Consumption of one half pound of the most contaminated duck would have been four times higher than the annual accepted dose of radiation. Shoreline roots and berries would have also been a source of contaminated food.

Anyone spending time along the shore, swimming or boating downstream from the Hanford reactors would have received some exposure. People of the area recall that in the 1950s and 1960s, swimmers preferred being near Hanford because the water felt warmer there than further downstream.


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