HANFORD
K Basins
Nearly 80 percent (2,100 metric tons) of the DOE's nationwide inventory of spent nuclear fuel is in the K Basins, located adjacent to the K East and K West Plutonium Production Reactors, which were shut down in 1970 and 1971. The function of the K Basins is the safe storage of irradiated reactor fuel until it can be disposed or transferred to a safer location. The fuel in the K West Basin is encapsulated; the fuel in K East Basin is not. Some laboratory processes, such as qualitative analyses, are conducted in the laboratory area, but only to identify radioisotopes. The only ongoing processes are treatment of the water and water filtration that occurs in the basin filtration system. Periodically, radioactive sludge from the basin floor is moved from one section of the basin to the other to concentrate this material.
The indoor basins, located in the 100-K Area, were built in 1951 and designed for a 20-year life. They were not designed for long term storage of spent reactor fuel, and they do not meet commercial nuclear or DOE safety and quality standards. The rectangular, reinforced concrete basins are 125 feet long, 67 feet wide, 21 feet deep and are divided into three sections. Each basin holds almost 1.2 million gallons of water. Nominal water depth above the fuel is 16 feet. The water provides a radiation shield for facility workers. A closed water treatment system maintains water purity. The water treatment system withdraws water from one end of each basin section, circulates it through filters and an ion exchange system to remove impurities, and discharges it back into the basin at the opposite end.
Beginning in 1975, the basins were used for spent nuclear fuel storage. PUREX was shutdown during the 1970s, but N Reactor continued to operate. The spent fuel assemblies from N Reactor each weigh about 52 pounds. The 26-inch long, 2.5-inch diameter fuel assemblies consist of metallic uranium within a zirconium cladding. The fuel was not designed for long term storage. It was to be stored for a short period of time (a maximum of 180 days) before being transported to PUREX, dissolved, and reprocessed to extract uranium and plutonium. The K West basin was drained, cleaned, and given an epoxy coating before spent fuel from N Reactor was placed there. The 1,000 metric tons of fuel in the K West basin were encapsulated in leak-proof canisters. Less than 1 percent of the spent fuel in K Basins is old aluminum-clad, single-pass reactor fuel slugs 6 inches long and 1.5 inches in diameter.
Of greater concern is the 1,100 metric tons of spent N Reactor fuel in the K East basin. K East basin was not refurbished, and the fuel in K East basin is stored in open canisters. Some of the fuel has been stored at the K East basin since 1975. Thousands of the spent fuel assemblies have broken cladding, allowing the basin water to reach the uranium metal fuel, which contains plutonium and highly radioactive fission products. Water corrodes the fuel, and the corrosion products are released into the basin water. Many corrosion products have been distributed around the K East basin as sediment. Enough sediment has accumulated over the years to form a sludge on the basin floor.
Between 1974 and 1979, an estimated 15 million gallons of contaminated water from K East basin leaked into the soil through a construction joint in the discharge chute area of the basin. The construction joint was repaired in 1980. Another leak of about 50 gallons per hour occurred in February 1993. It continued for several months and leaked an estimated 94,000 gallons of water before it stopped on its own.
The basins were not designed for either long- term spent reactor fuel storage or to maintain their integrity during a seismic event. The K Basins have, however, been qualified to current seismic standards. (During the winter and spring of 1995, barrier doors were installed between the discharge chutes and the basins in both the K East and K West basins.) The fuel continues to corrode and be deposited as sludge across the floor of the K East basin. The basins are located 1/4 mile from the Columbia River. The potential release of radioactive material to the environment is a serious concern. RL received permission to place this fuel in dry storage in the Canister Storage Buildin
Full-scale construction on the Canister Storage Building (CSB), a facility designed to provide interim storage of 2,300 tons of spent nuclear fuel, was underway in the late 1990s. On March 25, 1996, DOE Richland Operations Office manager John Wagoner signed the documentation formally granting substructure design approval and authorizing construction of the below ground portion of the building. The CSB, a 42,000-square foot, steel structure on a concrete operating deck, ins the east in the 200 East Area provides interim storage for SNF removed the K-basins. The CSB houses Step 3, the final step, in the Spent Nuclear Fuel Project. The CSB and its support facilities cost $157-million to build.
The K Basins Closure (KBC) Project was established in 2004, to remediate the two K Basins after they were emptied of approximately 2,300 tons (2,100 metric tons) of spent nuclear fuel. The fuel was removed between December 2000 and October 2004, by Hanford's Spent Nuclear Fuel Project.Following fuel removal, the basins still contained almost 70 cubic yards (54 cubic meters) of sludge, 2.4 million gallons of water, and hundreds of tons of solid waste. Most of the sludge had formed in the KE Basin.
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