Figure 1. DOE's Hanford Site and Surrounding Area.
The Hanford Site lies within the semiarid Pasco Basin of the Columbia Plateau in southcentral Washington State (Figure 1). The Site occupies an area of about 1,450 square kilometers (approximately 560 square miles) located north of the city of Richland and the confluence of the Yakima River with the Columbia River. This large area has restricted public access and provides a buffer for the smaller areas onsite that historically were used for production of nuclear materials, waste storage, and waste disposal. Only about 6% of the land area has been disturbed and is actively used. The Columbia River flows eastward through the northern part of the Hanford Site and then turns south, forming part of the eastern boundary. The Yakima River flows along part of the southern boundary and joins the Columbia River downstream from Richland. Land in the surrounding environs is used for urban and industrial development, irrigated and dry-land farming, and grazing. The cities of Richland, Kennewick, and Pasco (Tri-Cities) constitute the nearest population center and are located southeast of the Site.
Figure 1. DOE's Hanford Site and Surrounding Area.
The Hanford Site was established in 1943 to use technology that was developed at the University of Chicago and the Clinton Laboratory in Oak Ridge, Tennessee to produce plutonium for some of the nuclear weapons tested and used in World War II. Hanford was the first plutonium production facility in the world. Nearly all technology was developed as it was needed. The Site was selected by the U.S. Army Corps of Engineers because it was remote from major populated areas and had ample electrical power from Grand Coulee Dam, a functional railroad, and clean water available from the nearby Columbia River. The Site also contained sand and gravel that could be used for constructing large concrete structures. For security, safety, and functional reasons the Site was divided into numbered "Areas" (Figure 1).
Hanford operations have resulted in the production of liquid, solid, and gaseous wastes. Most wastes resulting from Site operations have had at least the potential to contain radioactive materials. From an operational standpoint, radioactive wastes were originally categorized as "high-level," "intermediate-level," or "low-level," which referred to the level of radioactivity present. Some high-level solid waste, such as large pieces of machinery and equipment, were placed onto railroad flatcars and stored in underground tunnels. Both intermediate-level and low-level solid wastes consisting of tools, machinery, paper, wood, etc., were placed into covered trenches at storage disposal sites known as "burial grounds." Beginning in 1970, solid wastes were segregated according to the makeup of the waste material. Solids containing plutonium and other transuranium materials were packaged in special containers and stored in lined trenches covered with soil for possible later retrieval. High-level liquid wastes were stored in large underground tanks. Intermediate-level liquid waste streams were usually routed to underground structures of various types called "cribs." Occasionally, trenches were filled with the liquid waste and then covered with soil after the waste had soaked into the ground. Low-level liquid waste streams were usually routed to surface impoundments (ditches and ponds). Nonradioactive solid wastes were usually burned in "burning grounds." This practice was discontinued in the late 1960s in response to the Clean Air Act, and the materials were instead buried at sanitary landfill sites. These storage and disposal sites, with the exception of high-level waste tanks, are designated as "active" or "inactive" waste sites, depending on whether or not the site currently is receiving wastes.
From the early 1940s to the present, most research and development activities at the Hanford Site were carried out in the 300 Area, located just north of Richland. The 300 Area was also the location of nuclear fuel fabrication. Nuclear fuel in the form of pipe-like cylinders ("fuel slugs") was fabricated from metallic uranium shipped in from offsite production facilities. Metallic uranium was extruded into the proper shape and encapsulated in aluminum or zirconium cladding. Copper was an important material used in the extrusion process, and substantial amounts of copper, uranium, and other heavy metals ended up in 300 Area liquid waste streams. In more recent times, the low-level liquid wastes were shipped to a solar evaporation facility in the 100-H Area (100-H Area Basins).
The fabricated fuel slugs were shipped by rail from the 300 Area to the 100 Areas. The 100 Areas are located on the shore of the Columbia River, where up to nine nuclear reactors were in operation. The main part of the nuclear reactors consisted of a large stack ("pile") of graphite blocks that had tubes and pipes running through it. The tubes housed the fuel slugs while the pipes carried cooling water that was eventually returned to the Columbia River. The large collection of slightly radioactive uranium in the reactor piles resulted in an extensive radiation field and a radioactive chain reaction that caused some uranium atoms to be converted into plutonium atoms. Other uranium atoms were split into radioactive "fission products." The intense radiation field also caused atoms in the structure to become radioactive "activation products."
The first eight reactors, constructed between 1944 and 1955, used water from the Columbia River for direct cooling. Large quantities of water were pumped through the piles and discharged back into the river. The discharged cooling water contained small amounts of radioactive materials that escaped from the fuel slugs, tube walls, etc. during the irradiation process. The radiation field in the pile also caused some of the impurities in the river water to become radioactive ("neutron activation"). The ninth reactor, N Reactor, was completed in 1963 and was of a slightly different design. Purified water was recirculated through the reactor core in a closed-loop cooling system. Beginning in 1966, the heat from the closed-loop system was used to produce steam that was sold to the Washington Public Power Supply System to generate electricity at the adjacent Hanford Generating Plant.
When fresh fuel was pushed into the front face of a reactor's graphite pile, irradiated fuel slugs were forced out the rear into a deep pool of water called a "fuel storage basin." After a brief period of storage in the basin and further storage in special freight cars on a railroad siding, the irradiated fuel was transported by rail to the 200 Areas where the plutonium was recovered. Most of the irradiated fuel produced at N Reactor from the mid-1970s to late 1983 was transported by railcar to the 100-K East and 100-K West fuel basins for "temporary" storage, where it remains today.
The 200 East and 200 West Areas are located on a plateau about 11 kilometers and 8 kilometers (7 and 5 miles), respectively, south of the Columbia River. These areas housed facilities that received and dissolved irradiated fuel and then separated out the valuable plutonium. These facilities were called "separations plants." Three types of separations plants were used over the years to process irradiated fuel. Each of the plutonium production processes used a feed stock derived from the dissolution of the aluminum or zirconium cladding material in ammonium hydroxide followed by the dissolution of the irradiated fuel slugs in nitric acid. Each of the three separations plants therefore produced large quantities of waste nitric acid solutions containing high levels of radioactive materials. These wastes were neutralized and stored in large underground tanks. Fumes from the dissolution of cladding and fuel, and other plant processes, were discharged to the atmosphere from tall smokestacks, which were filtered after 1950.
Both B Plant and T Plant used the "bismuth phosphate" process to precipitate and separate plutonium from acid solutions during the early days of Hanford operations. Leftover uranium and high-level waste products were not separated and were stored together in large underground "single-shell" tanks (tanks constructed with a single wall of steel). The leftover uranium was later salvaged, purified into uranium oxide powder at the Uranium-TriOxide (UO-3) Plant, and transported to uranium production facilities in other parts of the country for reuse. This salvage process used a solvent extraction technique that resulted in radioactive liquid waste that was disposed to ground in covered trenches at the B-C Cribs Area south of the 200 East Area. Cooling water from B Plant went to B Pond, cooling water from T Plant went to T Pond, and cooling water from U Plant and the Uranium-TriOxide Plant was routed to U Pond.
After T Plant was used as a separations facility it was converted to a decontamination operation where large pieces of equipment and machinery could be cleaned up for reuse. B Plant was later converted into a facility to separate radioactive strontium and cesium from high-level waste. The strontium and cesium were then concentrated into a solid salt material, melted, and encapsulated at the adjacent Encapsulation Facility. Canisters of encapsulated strontium and cesium were stored in a water storage basin at the Encapsulation Facility.
The Reduction Oxidation Plant (REDOX) in the 200 West Area and the Plutonium-Uranium Extraction Plant in the 200 East Area used solvent extraction techniques to separate plutonium from leftover uranium and radioactive waste products. Most of the irradiated fuel produced at Hanford was processed at either of these two facilities. The solvent extraction method separates chemicals based on their differing solubilities in water and organic solvents, i.e., hexone at the Reduction Oxidation Plant and tributylphosphate at the Plutonium-Uranium Extraction Plant. High-level liquid wastes were neutralized and stored in single-shell tanks (Reduction Oxidation Plant) or double-shell tanks (Plutonium-Uranium Extraction Plant). Occasionally, organic materials such as solvents and resins ended up in high-level liquid waste streams sent to the tanks. Because the solutions discharged to these tanks were not acidic, various chemicals and radioactive materials precipitated and settled to the bottom of the tanks. This phenomenon was later used to advantage--the liquid waste was heated in special facilities ("evaporators") to remove excess water and concentrate the waste into salt cake and sludge, which remained in the tanks. The evaporated and condensed water contained radioactive tritium and was discharged to cribs. Intermediate and low-level liquid wastes discharged to ground from the Reduction Oxidation and Plutonium-Uranium Extraction Plants typically contained tritium and other radioactive fission products as well as nonradioactive nitrate. Intermediate-level liquid wastes discharged to cribs from the Reduction Oxidation Plant sometimes contained hexone used in the Reduction Oxidation process. Cooling water from the Reduction Oxidation Plant was discharged to the Reduction Oxidation Plant Ponds. Cooling water from the Plutonium-Uranium Extraction Plant was discharged to Gable Mountain Pond and B Pond.
The Reduction Oxidation and Plutonium-Uranium Extraction Plants produced uranium nitrate for recycle and plutonium nitrate for weapon component production. Uranium nitrate was shipped by tank truck to the Uranium-TriOxide Plant for processing. The Uranium-TriOxide Plant used specially designed machinery to heat the uranium nitrate solution and boil off the nitric acid, which was recovered and recycled to the separation plants. The product, uranium oxide, was packaged and shipped to other facilities in the United States for recycle. Plutonium nitrate was placed (in small quantities for safety reasons) into special shipping containers ("P-R cans") and hauled by truck to the Z Plant for further processing.
Plutonium was received at one of several buildings operated over the years that were collectively known as Z Plant, now called the Plutonium Finishing Plant. The purpose of Z Plant operations was to convert the plutonium nitrate into plutonium metal blanks ("buttons") that were manufactured into nuclear weapons components. The conversion processes used nitric acid, hydrofluoric acid, carbon tetrachloride, and various oils and degreasers. Varying amounts of all these materials ended up in the intermediate-level liquid wastes that were discharged to cribs. Cooling water from the Z Plant was discharged via open ditch to U Pond. High-level wastes containing plutonium were segregated and packaged for storage in special earth-covered trenches.
In addition to research and development activities in the 300 Area, the Hanford Site has supported several test facilities. The largest was the Fast Flux Test Facility (FFTF) located in the 400 Area, about 8 kilometers (5 miles) north-west of the 300 Area. This special nuclear reactor was designed to test various types of nuclear fuel. The facility operated for about 13 years and was shut down in 1993. The reactor was a unique design that used liquid metal sodium as the primary coolant. The heated liquid sodium was cooled with atmospheric air in heat exchangers. Spent fuel from the facility resides in the 400 Area, while other wastes were transported to the 200 Areas. With the exception of the spent fuel, no major amounts of radioactive wastes were disposed of at the Fast Flux Test Facility site.
This area includes all of the Hanford Site not occupied by the 100, 200, 300, 400, 700, 1100, and 3000 Areas.
Areas near the Site in north Richland provide Site support services. These include the 1100, 3000, and Richland North Areas. The 1100 Area is the location for general stores and transportation maintenance. The 3000 Area includes facilities for ICF Kaiser Hanford Company and Boeing Computer Services. In 1995, both Kaiser and Boeing were in the process of vacating this area so that it can be made available for other uses. DOE and DOE contractor facilities, mostly office buildings, located between the 300 Area and the city of Richland but outside the 1100 and 3000 Areas are located in the Richland North Area. The 700 Area includes federal facilities in downtown Richland.
Several areas of the Site have special designations. These areas total 665 square kilometers (257 square miles) and include the Fitzner/Eberhardt Arid Lands Ecology Reserve, the U.S. Fish and Wildlife Service Saddle Mountain National Wildlife Refuge, and the Washington State Department of Fish and Wildlife Game Reserve Area (Wahluke Slope Wildlife Recreation Area).
Non-DOE operations and activities include com-mercial power production by the Washington Public Power Supply System's WNP-2 Reactor (near the 400 Area) and commercial low-level radioactive waste burial at a site leased and licensed by the state of Washington and operated by US Ecology (near the 200 Areas). Near the southern boundary of the Site, Siemens Power Corporation operates a commercial nuclear fuel fabrication facility, and Allied Technology Group Corporation operates a low-level radioactive waste decontamination, super-compaction, and packaging disposal facility.
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