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Appendix B The DOE Nuclear Weapons Complex: A Descriptive Overview Nuclear weapons are produced in the United States by the Office of Defense Programs (DP) of the Department of Energy (DOE). DP manages a large complex of facilities, including 17 major plants in 12 states, to carry out its mission. Its annual budget is about $10 billion, and DOE and its contractors employ about 80,000 people. For the purpose of description, we organize the facilities in the complex into three main types: the weapons laboratories, the materials production facilities, and the weapons production facilities. The weapons labs design the weapons providing the blueprints and technical specifi~cabons for their constructior~and test them. The materials production facilities provide the raw nuclear materials for fabrication into warheads. The weapons production facilities fabricate the required nuclear components, supply the hundreds of non-nuclear components, and assemble the warheads. In addition, DP manages He test facility and a waste repository for the operation, which is currently the Waste Isolation Pilot Plant in New Mexico. Figure B.1 presents a snapshot of the current status of the complex, which, over its Midyear history, has been configured in many different ways. It would be impractical to indicate all the previous rounngs. It can be seen that the complex has redundant capabilities for many processes, and in some cases, processes once required for stockpiles have been discontinued. WEAPONS LABORATORIES The three weapons laboratories are the Los Alamos National Laboratory (LANL) in Los Alamos, New Mexico; the Lawrence Liverrnore National 102
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APPENDIX B 103 Laboratory (LLNL) in Livermore, California; and the Sandia National Laboratory (SNL) in Albuquerque, New Mexico. Los Alamos National Laboratory and NIL are both large multipurpose complexes, and they both conduct many activities unrelated to nuclear weapons. Within the context of nuclear weapons production, however, these two labs have essentially the same missions: to design, develop, and test the nuclear components of the weapons. Both labs are operated under contract with the University of California Board of Regents. Between the two labs there is a vigorous competition, which has undoubtedly been beneficial to weapons design. Each lab has provided designs currently in the weapons stocl~ile, and each lab has several new designs under development. Sandia National Laboratory, like the other two labs, carries out many activities not associated with nuclear weapons. Part of its mission in the nuclear weapons complex is to design and engineer non-nuclear components associated with a nuclear weapon. Such components include electrical systems, fusing and hiring, neuron generators, tridum reservoirs, and delivery packages. SNL works closely with LANL and LLNL to incorporate the nuclear components of a new design into an operational.weapon. SNL also has responsibility for engineering modifications and upgrades to weapons already deployed and for monitoring the stockpile. MATERIALS PRODUCTION FACILITIES The materials production facilities include the gaseous diffusion plants at Oak Ridge in Tennessee, Paducah in Kentucky, and Piketon in Ohio; Herald, Ashtabula, Hanford; the Idaho Chemical Processing Plant, Y-12 at Oak Ridge, and the Savannah River Site. The mission of these facilities is to provide the nuclear materials used in nuclear weapons, particularly uranium-235, uraraum-23S, plutonium-239, lithium- 6, tritium, and deutenum. The first three are among the heaviest of elements, while the latter three are among the lightest Four of the six are produced by separation from naturally occurring ores and water. The other two, plutonium and tntium, are not available from natural sources but are produced in nuclear reactors by transmutation of other elements. Heavy Metal Production Uranium as found in the ground is mostly uranium-238 with 0.7 percent uranium-235 and 0.01 percent uranium-234. Uranium mills process the ores to produce a concentrated uranium oxide, U3O~, which then is commercially converted to gaseous uranium hexafluoride (UF: for enrichment processing in the gaseous diffusion plants (GDPs). There are three GDPs: the Oak Ridge GDP (K-25 Plant) in Tennessee, the Paducah GDP in Kentucky, and the Portsmouth GDP in Piketon, Ohio. The Oak Ridge GDP has been on standby since 1985. The purpose of these
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104 _ F SEU E DU _ R _ N t D · _·1 Uranium ~ ~ . ~nput ~ _ Gaseous diffusion Oak Ridge* _ . Paducah. _ _ . ~ Pc~ncmc,' nh _ H E U. Ingots SEU DU DU A S H T A B U L A. OAK RIDGE Y-12 Retired I _, wesponS ~ DU L~ _ DU scmp ~ r Spent Naval I ~ ~ HEU and research ! ~ Lithium bydroxide Li-6^ stockpile enrichment stockpile F etired weaponS=_| ~ Li~ _ D2O ~Not in operation at present APPE:NDIX B U03 Biliets HANFORD DU ~ N-Reactor. LEU nitrate ~ , HEU nitrate SAVANNAH RIVER HEU Fuel fabrication | Water _ Heavy water plant. r~ Heavy water rework ]! , Recycled D2O | D2O stockpile | SRS. IDU targets reactors | LL' targets FIGURF B.1 Plow of materials through the DOE Nuclear Weapons Complex. Diagram byP.Rapp 1989.
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APPENDIX B l U03 ~- ~ _ PUREX plant _ Plutonium Pu metal Finishing Plant I_ i Pu metal _ F-Canyon i Tritium facility : Filled reservoirs 1 ~ To deployed Tritium recycled weapons from weapons HEU 8 DU components ' Li~deuteride components Hasten, Tennessee (Army) Bulk explosive ROCKY FLATS Pu scrap Fission cores T3 reservoirs n ~ _ ~ ~ Kansas City Bendix Electronic, mechanical, plastic components Pinellas, Florida Neutron generators Retired weapons Mound, Ohio Actuators, igniters, detonators 105 PANTEX Recycled materials / V Nuclear weapons ~ _ V
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106 APPENDIX B plants is to concentrate the uranium-235. The mechanism for concentration is based on the fact that a UFO molecule containing uranium-235 is slightly lighter than a UFO molecule containing uranium-238; consequently, the former has a slightly higher thermal velocity. About two-thirds of the uranium-235 in the natural ore is removed in the concentration process, so that there are two product streams: enriched uranium and depleted uranium. Only the Portsmouth GDP is now operated to provide concentrations higher than 4 percent ~arnum-235. In general the enriched uranium may contain any percentage of uranium-235. Uranium containing more than 20 percent uranium-235 is called highly enriched uranium (HEU); enriched uranium with less than 20 percent uranium-235 is known as low enriched uranium (LEU). HEU production for weapons ceased in 1964. Before that iune, the gaseous HEU was shipped from Piketon to the Y-12 Plant, where it was converted to metal and stockpiled. The HEU metal is commonly known as "oralloy," where the first two letters indicate Oak Ridge. LEU was used for the fuelltarget rods at the Hanford N-Reactor, which is now on cold standby. For purposes of companson, the fuel in commercial power reactors is about 3 percent uranium-235, the driver fuel for the production reactors at SRS is typically 60 percent uranium-235, and naval reactor fuel is 97.3 percent uranium- 235. Depleted uranium (DU) is used both for SRS target rods and for components in weapons. There are two, almost independent' plutonium production streams. Bow streams start with enriched and depleted uranium in the gaseous state, and both streams provide plutonium metal to Rocky Flats. By far the largest effort in heavy metal production is devoted to the creation and processing of plutonium. The first stream to be described here flows through Fernald, Ashtabula, and Hanford. The second goes through INEL, Oak Ridge, and Savannah River. FernaldIAshtabula/~nford The LEU and Do products, still in the gaseous state, are shipped to the Feed Materials Production Center (FMPC) in Femald, Ohio. At the Fernald plant the UFO iS reduced to the "green salt," IJF4, and mixed with green salt produced from other inputs to the FMPC. The FMPC is a large and diverse facility containing 10 separate plants. Uranium input to the FbIPC enters in several forms, including ore concentrates, metal scraps and residues, uranyl nitrate (UNH) from SRS, and UO3 from Hanford. All these inputs are pr~ess~ ink uranium oxides, some of which may be shipped to the GDPs for enrichment. Most of the input, however, is processed into UO3 and hydrofluorinated into green salt, which is mixed with the green salt from reduction of UFO. I he green salt is reduced to metal and cast into ingots. Some of the DU is shipped to Y-12 for fabrication into weapons components. The LEU ingots, and the rest of the DU ingots, are machined and shipped to the `4shtabu~a Extrusion Plant in Ashtabula, Ohio. In Ashtabula the ingots are extruded into tubes and billets for later fabrication into reactor rods. The DU tubes are returned, first, to Femald for further machining, and then to
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APPENDIX B 107 SRS where they are usM as target rods for transmutation of uranium-238 into plutonium. The LEU billets go to Hanford to make fueVtarget rods for He N- Reactor, which is curmndy on cold standby. The DOE Modernization Report anticipates that the FMPC will be permanency closed in the near future. At the Fuel Fabrication Facility on the Hanford site, He LEU billets are fabricated into reactor elements by extrusion into rods clad with zirconium. These rods serve as both fuel and target in the N-Reactor. Neurons from fissioning uranium-235 conven some of the urarnum-238 to various isotopes of plutonium. The fissioning isotope, plumnium-239, is He one desired for both reactor fuel and weapons. As the uranium-235 is used up, the amount of plutonium increases, but the fraction of plutonium as plutonium-239 decreases as the relative abundance of plutonium-240 increases. "Weapons-grade" plutonium contains less than 7 percent plutonium-240, while '~fuel-grade" plutonium contains less than 13 percent plutonium-240. Other isotopes, plutonium-241 and plutonium- 242, are also produced by subsequent neutron capture. Consequently, the limit to the N-Reactor fuel cycle is determined not by the burn-up of uranium-235, but rather by the desired abundance of isotopes in the produced plutonium. Chemical processing of the irradiated reactor rods separates plutonium from the other elements. Chemical processing cannot' however, separate plutonium isotopes. Methods to do that are still under development. Chemical processing of the irradiated rods begins in the PUREX (plutonium- uranimn extraction) Plant on the Hanford site. The first step is the chemical removal of the fuel cladding in the head-end dissolver. Subsequently, the fuel is initially dissolved in an aqueous solution of nitric acid. An organic solvent is used to separate the nitrates of uranium, plutonium, and neptunium from the fission products. Further treatments with organic solvents and nitric acid solutions isolate the uranium, plutonium, and neptunium. The three major outputs from the PUREX Plant are IJNH, plutonium oxide (PuO2), and neptunium nitrate. The neptunium is shipped to SRS; the other two products are processed further at Hanford. The uranyl nitrate goes to the Uranium Oxide ((JO3) Plant, where it is calcined into uranium oxide powder. The powder is shipped either to the GDPs for enrichment or to the Fernald Plant for processing into metal. The plutonium oxide goes to the Plutonium Finishing Plant (PFP, or Z Plant). There the plutonium is precipitated as the oxalate, convened to PuO2 and fluorinated with gaseous hydrogen fluoride (HF). The resulting pink powder, PuF4, is reduced to metal with calcium (see Appendix D). The plutonium is shipped to Rocky Flats for fabrication into weapons components. PEP can also be used to recycle scrap plutonium from Hanford and Rocky Flats. - r - ICPP/Y-12/Savannah River The other heavy metal stream is somewhat newer, and it depends to some extent on heavy elements previously produced. An important input to this stream
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108 APPENDIX B is the spent naval fuel returned to the Idaho Chemical Processing Plant (ICPP), located on the site of the Idaho National Engineering Laboratory KNELT. Other inputs to ICPP include spent fuels from research and test reactors, both domestic and foreign. The main mission of IFPP is the recovery of highly enriched uranium for use in driver fuel in He SRS reactors. ICPP has extensive water- f~led storage and staging facilities, allowing fuel to be moved into head-end dissolution without exposure to air. The head-end facilities offer a variety of dissolution processes to accommodate the venous fuels and claddings. Subsequent processing is similar to He PUREX process, involving solvent extraction and purification. ICPP is distinguished by its capability for handling and recovering the highly enriched uranium of the returned naval fuels. Naval fuel returns are expected to increase rapidly, perhaps tripling over the next 10 years. The output product, powdered uranium oxide, is shipped to the Y-12 Plant at Oak Ridge for processing into SRS fuel. A secondary mission of ICPP is the recovery of krypton-85 from the spent fuels. The krypton-85 is shipped to Oak Ridge for commercial sale, largely for use in the detection of leaks. ICPP is the only source of krypton-85 outside the Soviet Union. The Y-12 Plant at Oak Ridge is a large multi-purpose facility with several different missions, both in materials production and in weapons production. One mission is to produce uranium metal of about 60 percent enrichment for use as SRS driver fuel. Because the several inputs to this metal production have varying enrichments, the process streams are carefully blended to produce the required enrichment. One input is the ICPP oxide, which may have originated with naval fuel or with reactor fuels. The other input is highly enriched uranyl nitrate from processing of spent fuels at SRS. To blend the product to the required enrichment' oralloy from the Y-12 stockpile is added to the mix, and the final uranium metal product is shipped to Savannah River. Unlike the Hanford N-Reactor, which uses reactor rods functioning simultaneously as fuel and target, the SRS reactors use independent fuel and target rods, made of different materials. At the SRS Fuel Fabrication Facility, the uranium metal from Y-12 is alloyed with aluminum and ex~uded into fuel rods with aluminum cladding. At the SRS Target Fabrication Facility, the hollow tubes of depleted uranium from Fernald are electroplated with nickel and bonded into aluminum cans to serve as target rods for transmutation into plutonium. The Target Fabrication Facility also assembles the lithium target rods for tritium production (see Light Element Production below). There are five production reactors at SRS, designated C, K, L, P. R. They were all designed with heavy water, D2O, as coolant and moderator, allowing great flexibility in the use of the reactors for production of various nuclear materials, including trivium and plutonium. The P. K, and L reactors are currently shut down because of safety concerns; the C-Reactor is being cannibalized, and the R- Reactor is permanently closed. Currently there is no plutonium production planned, at least in the near term, at SRS; the focus is on tritiurn production.
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APPENDIX B 109 After the rods are removed from a reactor, they are processed in different chemical separations facilities called '~canyons," because Hey are 30 feet wide by 60 feet high, and almost 900 feet long, heavily shielded in concrete and steel. Too radioactive for human occupation, the canyons are operated entirely by remote control. The PUREX Plant at Hanford is a similar canyon facility. At SRS, the H- canyon processes the discharged fuel rods to r~over the enriched uranium, while the F-canyon processes the irradiated DU target rods to recover the plutonium. Tritium is recovered from the lithium Beget rods in a separate Tritium Facility, where remote handling is not required (see Light Element Production below). The H canyon uses a modified PUREX process of dissolution and solvent extraction to recover He enriched uranium from the fuel rods. Highly enriched UNH is shipped to the Y-12 Plant to be recycled and blended back into new SRS driver fuel. LEU, also in the forth of UNH, is shipped to the Fernald Plant. The F
110 APPEND[X B contains more than 200 tons of it. To maintain its Purina, the D2O is periodically processed Trough the SRS Heavy Water Rework Unit and returned to the large SRS stocl$,ile. Supplies for weapons production are shipped from the SRS stockpile to Oak Ridge in the form of liquid heavy water. Li6 and Li6D Production at Y-12 At the Y-12 Plant the heavy water is processed together with metallic Li6 to produce lithium-6 deutende (Li6D). The Li6D is formed into weapons components and shipped to Pantex (see Weapons Production Facilities below). Li6, like heavy water, was extracted in large quantides at one time, but it is now drawn from existing stockpiles. Li6 is a stable isotope that makes up about 7.4 percent of natural lithium ores. Lithium itself is one of the most abundant elements. Dunng the l950s, thousands of tons of lithium hydroxide were purchased for the weapons program. Enrichment of Li6 was the mission of several large plants at Y-12. The basis of the enrichment process is the differential preference of li~ium-7 for mercury. With the introduction of mercury into aqueous lithium hydroxide, the lithium-7 will concentrate in the amalgam phase. Enrichment of Li6 required the use of very large amounts of mercury at Y-12. Production of Li6 stopped in 1963, after the accumulation of a large stockpile. Li6 components from retired weapons are resumed to Y-12 for recycling. In addition to its use in Li6D components, Li6 is also used for production of tritium in the SRS Factors. Enriched Li6 from Y-12 is shipped to the SRS Target Fabrication Facility, where it is alloyed with aluminum and canned as target rods for the reactors. Li6 is also used for control rods in the reactor cores, as well as for shielding around the core. The irradiated lithium is processed ire the SRS Tritium .,. . Any. Tritium Production at SRS The Tritium Facility is a"chemical separation facility," but the irradiated Li rods do not require remote-handling canyons for processing. The mission is T separation, p~f~cation, and loading. One input is the irradiated lithium-aluminum target rods. The targets are heated under vacuum, and the liberated gases include hydrogen, D, T. helium-3, and helium4. Palladium diffusion and cryogenic distillation are used to separate and purify He tritium. Another input to the Tritium Facility is the T recovered from deployed weapons which is contaminated with helium-3. ReseIvoirs filled with tritium are shipped from SRS to Pantex and to military installations. A new facility at SRS, the Replacement Tritium Facility, is almost complete and should begin to operate in 1990. The new facility is underground, and it uses new hydride technology that greatly reduces the amount of tritium in the filling plumbing, and is expected to reduce greatly the releases of T to the atmosphere. This facility will replace the gas handling and processing that is conducted in the existing tritium facility.
APPENDIX B 111 WEAPONS PRODUCTION FACILITIES Production of Weapons Components Of the six weapons production facilities—Kansas City, Mound, Pinellas, Y- 12, Rocky Flats, Pantex three are involved only with nonnuclear components. The Kansas City Bendix Plant supplies various electrical, mechanical, and plastic components; the Mound Facility manufactures igniters, detonators, and other small-scale pyrotechnic components; and the Pinellas General Electric Plant produces neutron generators and neutron detectors. The Y-12 Plant and the Rocky Flats Plant contain specialized machine shops that process raw nuclear materials into the finished components required by the warhead designs. The Y- 12 Plant bakes and machines Li6D into ceramic weapons components for shipment to Pantex. It also fabricates uranium components, from both enriched and depleted uranium. These components are shipped to Rocky Flats, where they are assembled, together with plutonium and beryllium components, into "pits," i.e., the shells of fissionable materials inside the high explosive of the weapons. The plutonium and beryllium components are fabricated at the Rocky Flats Plant. Many other metal components, including the stainless steel tritium reservoirs, are fabricated in the extensive metal-working facilities at Rocky Flats. The plutonium input comes pardy from Hanford and SRS, and partly from the retirement and scrap recycling operations at Rocky Flats itself. In line with its mission of pit assembly, Rocky Flats also has the mission of disassembling the pits from retired weapons. The recovered plutonium is chemically processed to remove americium, which is purified and shipped to Oak Ridge. Americium is removed either by molten-salt extraction or by dissolution in nitric acid, followed by ion exchange, peroxide precipitation, fluorination, and calcium reduction to metal. This process is also used for plutonium scrap recovery. Building 371 at Rocky Flats was added to the complex in 1981 to modernize and integram these operations, but it was closed after a short operational run because of design faults. Assembly and Disassembly of Weapons Finally, all the components are brought together for assembly at the Pantex Plant in Amarillo, Texas, and Mom there the devices are delivered to the Department of Defense. The Pantex Plant itself fabricates the chemical high explosives, which are assembled around the pits fabricated at Rocky Flats. Much of the recent work uses modern insensitive explosives, which come in bulk quantities from the Arrny facility in Holsten, Tennessee. At Pantex the high explosive (HE) is pressed into rough billets and machined to final shape. The HE components are prepared and assembled in special "bays," made of thick concrete and designed to vent an accidental explosion through the earth-covered r ~of. The bays are spaced to avoid sympathetic explosions.
112 APPENDIX B The find assembly of nuclear weapons takes pace in special assembly cells known as "Grave! Genies." Components going into the final assembly include the high explosives, the pits from Rocky Flats, He Li6D pans from Y-12, the Olled T reservoirs from SRS, and the many nonnuclear components from other facilities Scheduling and staging the shipment and inventor of these components is an indicate business. The completed warheads are staged oasis at Pantex before shipment to military installations. As a corollary ~ its mission of warhead assembly, Pantex is ~SQ responsible for disassembling rewed weapons. The nuclear components are returned to the plants that produce them for processing and recycling. Pantex is Be only Cecilia with He capability to disassemble nuclear weapons It is therefore the swing point for any maintenance or modification of weapons, excel for the replenishment of the trivium resenro~s. Pan tex also conducts quality assurance testing on components of deployed weapons.
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