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Hanford radiation releases

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Air Releases

Most of Hanford's air releases came from the chemical process used to separate plutonium and uranium from fuel rods. Some of the air releases came from the nuclear reactors. The major radioactive releases occurred between 1944 and 1957. The largest ones were from December 1944 through 1947 when there were no filters on the stacks of the separations plants. Radioactive materials in the form of gases, vapors, and particles went up the stacks. Left picture B-reactor.

Current Estimates of Radiation Released into the Air by Hanford, 1944-1972

Iodine-131 - 739,000 curies
Ruthenium-103 - 1,160 curies
Ruthenium-106 - 388 curies
Strontium-90 - 64.3 curies
Plutonium-239 - 1.78 curies
Cerium-144 - 3,770 curies

Columbia River Contamination

The first eight nuclear reactors at Hanford used large amounts of Columbia River water to cool the reactor cores. The water went through the reactors once before being returned to the Columbia River, even though the water contained radioactive materials. Radioactive materials that built-up inside the reactors were also regularly flushed loose and entered the Columbia River.

These eight reactors were operating at highest power between the late-1950s and mid-1960s. Contamination of the Columbia River was greatest during this time. The last of the eight reactors was shut down in January 1971.

HEDR now estimates that five radioactive substances account for most of the dose received from exposure to the Columbia River. They are arsenic-76, neptunium-239, phosphorus-32, sodium-24, and zinc-65.

People received exposure from the Columbia River by: eating contaminated fish and seafood; drinking contaminated water; swimming in or boating on the Columbia River; standing along the river shoreline or on a lawn irrigated with river water; and breathing dust blowing off exposed beaches or land irrigated with river water. Eating fish and seafood and drinking water were the main ways people were exposed to radiation from Hanford's reactors.

Current Estimates of Radiation Released into the Columbia River by Hanford, 1944-1971

Arsenic-76 - 2,500,000 curies
Neptunium-239 - 6,300,000 curies
Phosphorus-32 - 230,000 curies
Sodium-24 - 12,000,000 curies
Zinc-65 - 490,000 curies


The Release of Radioactive Material From Hanford: 1944-1972 - DOH

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