Aerial view of the Environmental Restoration Disposal Faciltiy, or ERDF, which receives wastes from Hanford Cleanup. (click photo for larger view)
The 200 Area, located on Hanford’s Central Plateau, is where chemical processing, plutonium finishing, and defense waste management activities took place. Beginning in 1944, fuel irradiated in the 100 Area reactors was taken to the 200 Area and chemically treated to remove and refine plutonium and uranium.
These chemical separations took place in both the eastern and western portions of the 200 Area NPL site. These portions of Hanford are called 200 East and 200 West.
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These processes produced radioactive, hazardous, and mixed (meaning both radioactive and hazardous) wastes, all of which have been stored or disposed in the 200 Areas. The 200 Areas contain 149 underground, single-shell storage tanks and 28 double-shell tanks capable of storing up to 3.79 million liters (one million gallons) each. These tanks store more than 200 million liters (53 million gallons) of high-level radioactive waste. Up to 67 of the single-shell tanks are known or suspected to have leaked between 3.79 and 7.58 million liters (1 and 2 million gallons) of waste, with some contaminants reaching groundwater.
Over the years, low-level radioactive liquid wastes from 200 and 300 Area facilities were discharged to Hanford Site soils through various trenches, drains, and cribs. A total of about 1.67 trillion liters (440 billion gallons) were disposed of onto site soils (not counting reactor cooling water that went to the Columbia River). Since 1995, when the Liquid Effluent Retention Facility began operations, discharging untreated liquid wastes to Hanford Site soils no longer occurs. The facility, along with two treated effluent disposal facilities built in the early 1990s, treats all contaminated discharges to remove radioactive chemicals before liquids are discharged to the soil.
Groundwater samples taken in the 200 Area show concentrations of many radioisotopes including tritium, uranium, strontium-90, cesium-137, and iodine-129. Chemicals including cyanide, carbon tetrachloride, and nitrate are also present in 200 Area groundwater. Cyanide is an organic compound that was used during uranium recovery, and carbon tetrachloride is a solvent that was used in the plutonium extraction process in the Plutonium Finishing Plant. Nitrate is also left over from chemical separations for plutonium extraction. Contaminants spread out in groundwater from the point of disposal into large fans known as plumes. Spreading from Hanford's 200 Area, the tritium plume is the largest and extends east to the Columbia River. In total, the 200 Area contains over 800 waste sites. Some of these sites have contaminated the groundwater.
Cleanup in the 200 Area has focused primarily on groundwater pump-and-treat facilities and transuranic waste retrieval. Approximately 96,000 kilograms (212,000 pounds) of carbon tetrachloride has been extracted from 200 West Area soils so far. Pump-and-treat and vapor extraction systems are in place in the 200 West Area and are capturing carbon tetrachloride, uranium, and technetium-99 from the groundwater. Thus far, over 1.14 trillion liters (300 million gallons) of contaminated groundwater has been pumped out, treated, and released as clean water. Approximately 13,100 kg (29,000 pounds) of carbon tetrachloride and over 250 kg (550 pounds) of uranium has been removed from the water.
The Plutonium Finishing Plant is undergoing decontamination and demolition. The plutonium has been stabilized and is ready for shipment offsite. The facility has been cleaned out and auxiliary facilities have been removed. DOE is currently retrieving transuranic waste and shipping the waste to the Waste Isolation Pilot Plant in New Mexico.
Over 32,100 drum-equivalents (covers both drums and boxes) have been removed from burial grounds in the 200 Area out of an estimated total of 75,000 drum-equivalents. About half of those drums contained transuranic waste. So far, over 11,400 drums have been packaged and sent to the Waste Isolation Pilot Plant in New Mexico for disposal.
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