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APPENDIX C. FACILITY AND PROCESS DESCRIPTIONS

This appendix describes the principal facilities associated with the nuclear materials described in this environmental impact statement. The operations described are historic; the descriptions do not indicate how DOE would implement the alternatives discussed in this EIS. Figure C-1 shows the historic cycle and facilities used to produce, process, and store nuclear materials at the Savannah River Site. Chapter 2 describes the operations that would be associated with the alternatives, and includes short descriptions of proposed facilities or major modifications of SRS structures that would affect the alternatives, and of waste management facilities that would process wastes associated with stabilizing nuclear materials.

C.1 Fuel and Target Fabrication (M-Area)

M-Area (see Figure C-2) contains facilities used historically to fabricate fuel, special targets, and components for SRS production reactors. The facilities contain conventional equipment for melting, casting, and shaping metal, including furnaces, extrusion presses, lathes, handling equipment, and storage racks.

Buildings 313-M, 321-M, and 320-M contain the equipment used to fabricate depleted uranium targets, reactor fuel, and tritium targets, respectively. Building 321-M also contains the extrusion presses and finishing equipment that DOE used to extrude neptunium-237 oxide billets into neptunium targets, which were irradiated to produce plutonium-238. "Deinventory" of the facility (i.e., packaging unused nuclear materials and placing them in storage at the SRS or returning them to their sources) is underway. Buildings 313-M, 320-M, and 322-M (the Metallurgical Laboratory) have been deinventoried. Building 321-M is being deinventoried at present.

The SRS received raw aluminum, uranium, lithium, etc., at Building 315-M from commercial vendors and other DOE sites. The raw materials were cast, extruded, and machined into long cylindrical tubes or short cylindrical slugs of metal, depending on whether the reactor component was fuel or target. After fabrication, the fuel and targets were shipped to a reactor area (C, K, L, P, or R) for irradiation.

C.2 Reactors

Of the five production reactors constructed at the SRS in the early 1950s, four (C, L, P, and R) have been permanently shut down, and one (K-Reactor) is in indefinite "cold standby," (Figure C-3). R-Reactor is scheduled for decontamination and decommissioning.

Figure C-1.

Figure C-2.

Figure C-3.

Each reactor has an assembly area for the receipt, handling, and storage of new (i.e., unirradiated) fuel and targets. Racks and vaults store new fuel and targets. Similarly, each reactor has a disassembly area for the storage, handling, and shipment of irradiated fuel and targets that have been removed from the reactor. The disassembly area consists primarily of water-filled basins with metal racks designed for vertical or horizontal storage of fuel tubes, and metal buckets for storing targets. The disassembly basins are about 49 meters (160 feet) wide, 67 meters (220 feet) long and 5 to 9 meters (17 to 30 feet) deep. The volume of water in the basins ranges from 12,800,000 to 18,200,000 liters (3,380,000 to 4,800,000 gallons). The K- and L-Reactor disassembly basins are identical; the P-Reactor basin is the largest. The basins are constructed of unlined concrete coated with vinyl paint. Each has systems for circulating, filtering, and deionizing the water to maintain proper chemistry. Cranes, rigging, and handling equipment in the disassembly area can move or load fuel in casks for shipment to other areas on the Site.

Fuel and targets from M-Area were placed in storage racks or concrete vaults, then were grouped into assemblies and placed in a reactor core. The irradiation of the targets and fuel produced special isotopes. The irradiation time depended on the isotope to be produced. After their removal from the reactor core, the targets and fuel were placed in the water-filled basin to cool the fuel and targets and to allow the decay of short-lived radioactive products. The water also provided radiation shielding to operating personnel. After the targets or fuel had cooled for a brief period (12 to 18 months), they were disassembled and loaded in heavily shielded casks on rail cars (see Figure C-4), which were transferred to F- or H-Area for further processing.

C.3 Chemical Separations (F-Canyon and H-Canyon)

The similar F- and H-Canyon facilities use radiochemical processes for the separation and recovery of plutonium, neptunium, and uranium isotopes. The F-Canyon separated plutonium, irradiated natural or depleted uranium, and radioactive decay products. H-Canyon recovered uranium, highly enriched uranium-235, neptunium-237, and plutonium-238 from irradiated reactor fuels and targets. The following paragraphs apply to both canyons unless noted.

The F- and H-Canyons (see Figures C-5 and C-6; Figure C-6 also shows the Defense Waste Processing Facility in the adjoining S-Area) are reinforced concrete structures, 255 meters (836.6 feet) long, 37 meters (308 feet) wide, and 20 meters (121.4 feet) high. They are named for the two areas ("canyons") in each structure that house the large equipment (tanks, process vessels, evaporators, etc.) used in the chemical separations processes performed in each facility. The canyons are long (170 meters or 557.7 feet), narrow (an average of 6 meters or 19.7 feet), and deep

Figure C-4.

Figure C-5.

Figure C-6.

(20 meters or 65.6 feet). The "hot" and "warm" canyons in each facility are parallel and open from floor to roof. A center section, which has four floors or levels, separates the canyons. The center section contains office space, the control room for all facility operations, and support equipment such as ventilation fans. Figure C-7 is a cross-section view of a canyon facility. Processing operations involving high radiation levels (dissolution, fission product separation, and high-level radioactive waste evaporation) would occur in the hot canyon, which has thick concrete walls to shield people outside the facility and in the center section from radiation. The final steps of the chemical separations process, which generally involve lower radiation levels, would occur in the warm canyon.

Figure C-7. F-Canyon building sections.

Services typical for a large industrial chemical facility are required to support F- and H-Canyon operations. For example, steam heats process vessels and is the motive force for transferring solutions through process cycles; lights, motors, control systems, etc., use electricity; compressed air provides pressure needed for various process monitoring systems (e.g., liquid level indicators) and powers some control systems; and a ventilation system provides conditioned air for the comfort of facility workers and for environmental control for the operation of sensitive equipment.

A separate ventilation system serves portions of the facility, such as the hot and warm canyons, that contain the radioactive process equipment. This system ensures the air pressure in such areas is below the pressure of the air outside the facility and the area occupied by workers. This design helps prevent the release of radioactive material outside the facility by ensuring that air always flows from outside to inside the process areas. Air in the process areas is exhausted from the facility through a large sand filter that removes 99.5 percent of any airborne radioactive material. A 61-meter (200-foot)-tall stack behind each canyon discharges this filtered air to the atmosphere and serves as the pathway for airborne emissions associated with the normal operation of the canyons.

There are two primary pathways for liquid effluents from the canyons:

• Condensates from secondary evaporators at the A-Line Outside Facilities containing low levels of radionuclides flow to the Effluent Treatment Facility (ETF) for further decontamination, if necessary, before their discharge to surface waters.
• A water system cools the hot and warm canyon process vessels. Underground pipes carry water to the canyons and distribute it. The water passes through coils inside the vessels (Figure C-8 shows a standard canyon process vessel) and flows back out of the canyon. Constant monitoring detects radioactivity in the water. If radioactivity is detected, the water is diverted to a treatment facility where the radioactivity is reduced below applicable limits before the water is discharged.

The equipment and processing stages in the canyons have been configured to separate and recover uranium and plutonium from irradiated fuel or targets, as described for each canyon in the following paragraphs.

C.3.1 F-Canyon (PUREX) Process

The PUREX process consists of several major operations, referred to as "unit operations," which recover plutonium and uranium from irradiated reactor targets. The targets normally would be fabricated from uranium depleted in a uranium-235 isotopic (e.g., at a level below the naturally occurring 0.711 weight percent). The irradiation process is designed to produce weapons-grade plutonium [i.e., plutonium that is greater than 93 percent plutonium-239, with the remainder of the plutonium isotopes similar to plutonium-240 and -241 (NAS 1994)]. The major unit operations are dissolution, head end, first cycle, second uranium cycle, and second plutonium cycle (see Figure C-9). Unit operations that support the product recovery operations are high-activity waste,

Figure C-8.

Figure C-9. Historic PUREX process flow.

low-activity waste, solvent recovery, laboratory waste evaporation, etc. The F-Canyon process also has recovered neptunium-237 that results from PUREX process waste; this activity, which is no longer performed, is not part of this evaluation. Processes within the inner box are conducted in F-Canyon.

The following paragraphs describe major and support unit operations in F-Canyon:

• Dissolution - Irradiated targets on a rail car through an air lock are brought into the south end of the hot canyon. Each target consists of a cylinder of depleted uranium clad in aluminum. The targets have been irradiated in an SRS reactor to transform a portion of the depleted uranium into plutonium. Large water-filled casks on rail cars transfer the targets. The targets are removed from the casks and loaded into a large tank called a dissolver. Sodium hydroxide removes the aluminum cladding from the targets. The cladding solution is transferred to the high-level waste tanks. Heated nitric acid in the tank dissolves the target, resulting in a solution containing depleted uranium, plutonium, and radioactive decay products from the reactor irradiation process.
• Head End - This process occurs in two steps to prepare the target solution for uranium and plutonium separation. First, gelatin is added to precipitate silica and other impurities. Then the solution is transferred to a centrifuge where silica and other impurities are removed as waste. The clarified product solution is adjusted with nitric acid and water in preparation for the first cycle unit operation. The waste stream generated from the process is chemically neutralized and sent to the F-Area high-level waste tanks. The major components for this operation are a gelatin "strike" tank, a centrifuge feed tank, and a centrifuge.
• First Cycle - First cycle operation, which occurs in the hot canyon, has two functions: (1) to remove fission products and other chemical impurities, and (2) to separate the solution into two product streams (uranium and plutonium) for further processing. This separation process occurs as the product solution passes through a series of equipment consisting of a centrifugal contactor and mixer-settler banks. Before the introduction of the feed solution from the head end process, flows of solvent and acid solution are established in the equipment. When an equilibrium is established, the feed solution is introduced. The chemical properties of the acid/solvent/feed solutions in contact with each other cause radioactive decay products to separate from the uranium and plutonium. Later in the first cycle process, the plutonium is separated from the uranium in a similar manner. The first cycle produces four process streams: plutonium (with some residual radioactive decay products), which goes to the second plutonium cycle; a uranium solution (with some residual radioactive decay products), which goes to the second uranium cycle; a solvent stream, which goes to the solvent recovery cycle; and an aqueous acid stream, which goes to the high-level waste tanks. The acid stream contains most of the radioactive decay products. The equipment for this operation consists of a centrifugal contactor, mixer-settler banks, decanter tanks, and hold tanks.
• Second Uranium Cycle - The second uranium cycle (in the warm canyon) purifies the uranium solution from the first cycle and prepares the uranium for transfer to the FA-Line. The purification process is a separation process that occurs in a manner similar to that described for the first cycle. The uranium product solution, which contains a low concentration of radioactive decay products, is transferred from the warm canyon to storage tanks in the FA-Line facility, which is adjacent to the F-Canyon.
• Second Plutonium Cycle - The second plutonium cycle (in the warm canyon) purifies the plutonium solution from the first cycle by removing residual radioactive decay products, and prepares the plutonium for transfer to FB-Line. The purification process is a separation process that occurs in a manner similar to that described for the first cycle. The impurities are removed in an aqueous stream that goes to the low-activity waste unit operation for processing. The plutonium product solution, which contains a low concentration of radioactive decay products, is transferred to hold tanks for use as FB-Line feed material.
• High- and Low-Activity Waste - These unit operations reduce the volumes of the aqueous streams that contain radioactive decay products by using a series of evaporators in the hot and warm canyons. The feed to the evaporators originates with the primary separation process unit operations, such as the first cycle. The evaporator overheads, which contain most of the water and acid and very little of the radioactive decay product and chemicals used in solvent extraction, are transferred to tanks outside the building for acid recovery and recycling. The radioactive decay products and chemicals in the evaporator concentrate are neutralized and sent to the F-Area high-level waste tanks.
• Solvent Recovery - The primary purpose of this unit operation is to wash the solvent to remove impurities, and to recover the solvent and recycle it to solvent extraction cycles for reuse. This operation reconditions and removes impurities from the solvent. The impurities are transferred to low-activity waste for processing. A separate solvent recovery is used with each extraction cycle.
• Laboratory Waste Evaporation - The waste handling facilities receive high-level laboratory wastes from F-Area and the Savannah River Technology Center (SRTC) laboratories (see Section C.6.6) and transfer them to the warm canyon for evaporation. These wastes are evaporated and the recovered water is returned to the Outside Facilities for recycling and reuse. The concentrated waste is discharged to the F-Area high-level waste tanks.

C.3.2 H-Canyon Process

The H-Canyon process consists of the recovery of highly enriched uranium (HEU) from reactor fuel and the recovery of neptunium-237 and plutonium-238 from targets. This EIS evaluates the highly enriched uranium, but not the neptunium-237 and plutonium-238 processing. The major unit operations associated with highly enriched uranium are dissolution, head end, first solvent extraction cycle, second uranium solvent extraction cycle, and second neptunium (or second actinide) solvent extraction cycle (see Figure C-10). Unit operations that support the product recovery operations are high-activity waste, low-activity waste, and solvent recovery.

Figure C-10. Historic H-Canyon process flow.

The following paragraphs discuss major and support unit operations in H-Canyon:

• Dissolution - Irradiated reactor fuel on a rail car through an air lock is brought into the south end of the hot canyon. The fuel consists of highly enriched uranium fuel tubes clad in aluminum. As a result of the irradiation process, some of the material in the fuel was converted into radioactive decay products and other isotopes such as neptunium-237. Large water-filled casks on rail cars transport the fuel. The fuel is removed from the casks and loaded into a dissolver tank. Heated nitric acid and mercuric nitrates in the tank dissolves the fuel, resulting in a solution containing highly enriched uranium, neptunium, small quantities of plutonium, radioactive decay products from the reactor irradiation process, and the aluminum cladding.
• Head End - This process occurs in two steps to prepare the target solution for uranium and neptunium separation. First, gelatin is added to precipitate silica and other impurities. Then the solution is transferred to a centrifuge, where silica and other impurities are removed as waste. The clarified product solution is adjusted with nitric acid and water in preparation for the first cycle unit operation. The waste stream generated from the head end process is chemically neutralized and sent to the H-Area high-level waste tanks. The major components for this operation are a gelatin "strike" tank, a centrifuge feed tank, and a centrifuge.
• First Cycle - This operation, which occurs in the hot canyon, has two functions: (1) to remove radioactive decay products and other chemical impurities, and (2) to separate the solution into two product streams (highly enriched uranium and neptunium if recovery is scheduled) for further processing. During the solvent extraction process, the product solution passes through a series of mixer-settler banks. Before the introduction of the highly enriched uranium and neptunium feed solution, flows of solvent and acid (including nitric acid, as discussed for F-Area) solution start through the equipment. When equilibrium has been established, the feed solution from the head end is introduced. The chemical properties of the acid/solvent/feed solutions in contact with each other cause the radioactive decay products, the uranium, and the neptunium to separate. The first cycle produces four process streams: a highly enriched uranium solution with most of the radioactive decay product removed, which goes to the second uranium cycle; a neptunium solution with most of the radioactive decay products removed, which goes to the second neptunium cycle; a solvent stream, which goes to the solvent recovery system; and an aqueous acid stream containing most of the radioactive decay products and chemical salts used in the process, which goes to the high-level waste evaporators. If neptunium recovery is not desired, the solvent extraction cycle is revised and the neptunium is discarded with the aqueous acid stream. The equipment for this unit operation consists of mixer-settler banks, decanter tanks, and hold tanks.
• Second Uranium Cycle - The second uranium cycle (in the warm canyon) further purifies the highly enriched uranium solution from the first cycle and prepares it for transfer to the A-Line. The purification process is a solvent extraction process that occurs in a manner similar to that described for the first cycle. The highly enriched uranium product solution is transferred from the warm canyon to storage tanks in the A-Line facility, which is adjacent to the H-Canyon.
• Second Neptunium (Second Product) Cycle - The second neptunium cycle (in the warm canyon) purifies the neptunium solution from the first cycle if neptunium recovery is required by removing most of the residual radioactive decay products, and prepares the neptunium for transfer to HB-Line. The purification process is a solvent extraction process that occurs in a manner similar to that for the first cycle. The impurities are removed in an aqueous stream that goes to the low-activity waste unit operation for processing. The neptunium product solution is transferred to hold tanks for use as HB-Line feed material.
• High- and Low-Activity Waste - These unit operations reduce the volumes of the aqueous streams that contain radioactive decay products by using a series of evaporators in the hot and warm canyons. The feed to the evaporators originates with the primary separation process operations (e.g., the first cycle). The evaporator overheads, which contain most of the water and acid and very little of the radioactive decay product and chemicals used in solvent extraction, are transferred to tanks outside the building for acid recovery and recycling. The fission products and chemicals in the evaporator concentrate are neutralized and sent to the H-Area high-level waste tanks.
• Solvent Recovery - The primary purpose of this unit operation is to wash the solvent to remove impurities, and to recover and recycle the solvent extraction for reuse. The impurities are transferred to low-activity waste for processing. Solvent recovery is used with each extraction cycle.

C.4 FB-Line

The FB-Line is located on the top of the F-Canyon structure (see Figure C-11). Its exterior walls and roof are poured reinforced concrete. The portion of the structure that contains process equipment is approximately 39 meters (130 feet) long by 20 meters (67 feet) wide. The single-story extension to the north is about 11 meters (35 feet) wide by 6 meters (20 feet) long. Tanks and reaction vessels are enclosed in engineered cabinets or gloveboxes to minimize the spread of contamination and to provide shielding from radiation (see Figure C-12).

The FB-Line process includes purification and concentration of plutonium by cation exchange, precipitation of plutonium as a trifluoride, recovery of the trifluoride by filtration, drying of the trifluoride in an oxygen atmosphere, and reduction with calcium metal to form plutonium metal buttons. Figure C-13 shows the typical process flow through the line.