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Hanford 100-Area (USDOE)

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Site Summary

A cloud of sludge forms as the lid is removed from a cannister of spent fuel in the Hanford K-Basins. A thick layer of sludge has been deposited on the bottom of the basins.

The Hanford 100 Area is a 26-square-mile piece of land along the Columbia River where nine water-cooled plutonium reactors were constructed between 1943-1963. There are six reactor areas (three of which contain two reactors each and three that contain one reactor each) in the 100 Area. All nine reactors were operating at one point during the early 1960s, but only N Reactor (which produced both plutonium and electricity) remained in operation after 1971.

One of the major cleanup priorities in the 100 Area is the K Basins, located adjacent to the K West and K East reactors. More than 2,315 tons of spent nuclear fuel, or nearly 80 percent of USDOE’s nationwide reserve, was stored in these concrete basins. Located a few hundred meters from the Columbia River, the 40-year-old basins do not meet current safety standards, and one has leaked several times in the past. All of the fuel has been removed and sent to the Central Plateau for storage.


The fuel resided in the basins for decades and deteriorated. Some of the material formed a sludge on the bottom of the basins. Sludge removal is ongoing and the basins are expected to be drained in the next several years.


Hide details for Click directly on the triangle to the left for more Site HistoryClick directly on the triangle to the left for more Site History

    The 100 Area is a 67.4 square-kilometer (26-square-mile) piece of land along the Columbia River where nine water-cooled plutonium reactors were constructed between 1943-1963. There are six reactor areas (three of which contain two reactors each and three that contain one reactor each) in the 100 Area. All nine reactors were operating at one point during the early 1960s, but only N Reactor (which produced both plutonium and electricity) remained in operation after 1971. The N Reactor began weapons production operations in December 1963. In 1966, the Washington Public Power Supply (now Energy Northwest) built a power generating facility to harness steam from the reactor to generate electricity.

    Producing over 65 billion kilowatts in 24 years, N Reactor was the largest producer of electric power in the country in its early years. The other eight reactors are B Reactor (1944-1967); F Reactor (1945-1965); D Reactor (1944-1967); F Reactor (1945-1965); DR Reactor (1950-1964); H Reactor (1949-1965); C Reactor (1952-1969); KW Reactor (1955-1970); and KE Reactor (1955-1971).

    While in operation, the reactors disposed of cooling water and solid wastes in over 400 waste sites, trenches, cribs (underground drain fields), ponds, and burial grounds in the 100 Area. Also, leaks in the reactors’ wastewater piping and retention systems led to soil and groundwater (which ultimately flows into the Columbia River) contamination. The 100 Area has approximately 28.5 square kilometers (11 square miles) of contaminated groundwater and waste disposal locations.

    Remediation of soil waste sites in the 100 Area began in the mid-1990s. Since then, over 5.45 million metric tons (6 million tons) of contaminated soil have been retrieved and moved to the Environmental Restoration Disposal Facility (ERDF) in the Central Plateau. ERDF is a lined landfill that meets the technical design requirements of a hazardous waste landfill. Soil cleanup operations in the 100 Area are predicted to last until at least 2012 and involve removing an estimated 9.1 metric tons (10 million tons) of waste from the 100 and 300 areas. Additionally, “pump and treat” systems and other in-place treatment systems are in use to reduce levels of contaminants in 100 Area groundwater sites.

    Much of the groundwater is being treated, but there is still slow seepage of some contaminants to the Columbia River through groundwater. Monitoring results show that concentrations of radionuclides identified in the river, however, are within the drinking water standards set by the EPA and Washington State. Active pump and treat systems address chromium contamination to protect aquatic organisms, specifically salmonids.

    The 100 Area reactors are being remediated through a part of the Interim Safe Storage Project known as “cocooning.” Beginning in late 1996, all of the wings were torn off each reactor building; hundreds of metric tons of asbestos, steel, copper, and contaminated soil were removed, and the old pumphouse, pumps, tunnels and other parts of the structure were demolished. The core and the surrounding shields are all that were left. They were then sealed up and given a new aluminum and zinc-coated roof slanted to allow for rain run-off. The first Interim Safe Storage Project was completed in October 1998. Presently, interim safe storage projects are completed at C, F, D, DR and H. Interim safe storage projects in the future will address KE, KW, and N reactors. The B Reactor is being studied for use as a museum and still retains all of its original structures.

    One of the major cleanup priorities in the 100 Area is the K Basins, located adjacent to the K West and K East reactors. More than 2,100 metric tons (2,315 tons) of spent nuclear fuel, or nearly 80 percent of USDOE’s nationwide reserve, was stored in these concrete basins. Located a few hundred meters from the Columbia River, the 40-year-old basins do not meet current safety standards, and one has leaked several times in the past. All of the fuel has been removed and sent to the Central Plateau for storage. The fuel resided in the basins for decades and deteriorated. Some of the material formed a sludge on the bottom of the basins. Sludge removal is ongoing and the basins are expected to be drained in the next several years.


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