Plutonium processing manufacture

Plutonium is manufactured in megagram quantities neptunium, americium, and curium in kilogram quantities californium in gram amounts berkelium in 100-milligram amounts and einsteinium in milligram quantities. Chemical separations play a key role in the manufacture of actinide elements, as well as in their recovery, and analysis in the nuclear fuel cycle. This collection of timely and state-of-the-art topics emphasizes the continuing importance of actinide separations processes. 

Thus, safety problems of the process of plutonium ceramics manufacture are exceptionally multifaceted. We have tried to consider them at two basic stages ... 

Liquid extraction is utilized by a wide variety of industries. Applications include the recovery of aromatics, decaffeination of coffee, recovery of homogeneous catalysts, manufacture of penicillin, recovery of uranium and plutonium, lubricating oil extraction, phenol removal from aqueous wastewater, and extraction of acids from aqueous streams. New applications or refinements of solvent extraction processes continue to be developed. 

Interest in the so-called sol-gel process for the remote-controlled manufacture of plutonium-containing fuel rods is increasing due to its high safety. In this process a filter cake of freshly precipitated uranium(IV) oxide is converted ultrasonically into a U02-gel, which after drying is fired at 1150°C. The resulting microspheres, 40 to 60 t,m in diameter, are then poured into casing tubes using vibratory techniques. 

In their manufacture uranium(IV) oxide is mixed with the appropriate quantity of plutonium(IV) oxide, the mixture pressed into pellets and then sintered (termed coprocessing in the USA). Uranium(IV) oxide is produced by one of the above-described processes and plutonium(IV) oxide from the aqueous nitrate solution produced during reprocessing by precipitating it as plutonium oxalate and calcining the oxalate. 

These mixed oxides can also be manufactured by mixing the uranium and nitrate solutions produeed during the reprocessing of spent nuclear fuels and converting these metal nitrate mixtures into a mixed oxide (coprecipitation). In this process the plutonium is first reoxidized, then gaseous ammonia and carbon dioxide are introduced into the aqueous nitrate mixture, whereupon ammonium uranyl-plutonyl carbonate is precipitated. This can be calcined to... 

In addition to uranium, only a few other actinides have commercial uses. Currently, thorium is used to manufacture portable gas lanterns. Thorium oxide is used to make high-quality glass and is also a catalyst in various industrial processes. Plutonium also has commercial uses in uranium reactors and as fuel in nuclear reactors. 

It is important also to note that the process of immobilization covers not only metal (weapons) plutonium, but also Pu-containing solutions and precipitates of complex chemical structure, accumulated as a result of manufacture of a nuclear weapon. 

In the case of melting, the reduction of the stages of ceramics manufacture seems an essential advantage in comparison with technologies of plutonium reextraction from the precipitates with a subsequent processing by a separate scheme. 

Thus, the production of ceramics is not now less safe than the manufacture of glass and can be considered as the most promising technology for immobilization of plutonium in the near future. It is necessary to take into account also that in itself ceramics are the safest and steadiest form for fixing of plutonium for a long period of time compared to the duration of geological processes. 

Manufacturing processes are implemented with sealed equipment— the first barrier. The cask (container) is the first barrier for the plutonium dioxide in storage ... 

Radioactive waste Waste material containing radioactive elements in amounts greater than those normally present in the environment. Such waste is generated in large amounts by nuclear reactors used for production of electric power or of plutonium for weapons manufacture. Much low-level waste also results from uranium and phosphate mining and milling, industrial processes, laboratory research, and discarded materials that were used in medical diagnosis and therapy. 

MOX fuel is a next-generation fuel material that is manufactured for use in LWRs using excess plutonium, either from weapons programs or as a recycled product from the reprocessing of LWR fuels. The primary difference in fabrication of MOX fuel from that of UO2 is the need for all operations to be carried out in a radiological-controlled hot-cell environment due to the toxicity of the reprocessed fuel. This adds considerable complexity to all processes involved, requiring automation, remote operations, and robotics. 

The operations and facilities include ore exploration (not included in NFCIS list), mining, ore processing, uranium recovery, chemical conversion to UO2, UO3, UF4, UFg, and uranium metal, isotope enrichment, reconversion of UF to UO2 (after enrichment), and fuel fabrication and assembly that are all part of the front end of the NFC. The central part of the NFC is the production of electric power in the nuclear reactor (fuel irradiation). The back end of the NFC includes facilities to deal with the spent nuclear fuel (SNF) after irradiation in a reactor and the disposal of the spent fuel (SF). The spent fuel first has to be stored for some period to allow decay of the short-lived fission products and activation products and then disposed at waste management facilities without, or after, reprocessing to separate the fission products from the useful actinides (uranium and plutonium). Note the relatively large number of facilities in Table 2.1 dedicated to dealing with the spent fuel. Also listed in Table 2.1 are related industrial activities that do not involve uranium, like heavy water (D2O) production, zirconium alloy manufacturing, and fabrication of fuel assembly components. 

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