Fuel fabrication

The enriched UFg is converted into UO2 at the fuel fabrication plants. The IT6 is reacted with water to produce a solution of U02F2 and HF  

Ammonium hydroxide is added to the uranyl fluoride solution to quantitatively precipitate ammonium diuranate 

This product is collected, calcined in air to produce U3Og, and heated with hydrogen to make U02 powder. The U02 powder is pressed into pellets, which are sintered, 

Plutonium Storage Study, i4. Uriarte Hueda, F Rufz Sinchez (Junta de Energia Nuclear-Spain) 

This documoit contains a study on the storage of the plutonium that will be produced in Spain by nuclear power plants, as a previous step before deciding Its subsequent utilization. 

A study of this type must take several factors into account, such as evaluation of the plutonium produced in terms of the installed nuclear electrical power, and of the e and characteristics of planned nuclear reactors, diemical form, and isotopic composition of the plutonium to be stored, possible storage systems, and safety standards to be adopted (criticality, fire protection, shielding, flooding, heat elimination, earthquakes, etc.). The e q ectations of the Spanish Electricity Plan have been used as a basis for this study, which assumes an. installed nuclear electrical power of 23,500 MW(e) by the year 1985. 

Taking into account the number, type, and characteristics of the planned nuclear reactors, for an average production of irradiated fuels of 35 MTU/yr per 1000 installed MW(e), it has been estimated thsU the total amount of plutonium recovered in the treatment of irradiated fuels will be S7 MT up to 1990. For this study, the following isotopic composition has been taken 1.8% ( Pu) 59.2% ( Pu) 23.2% ( Pu) 12.0% ( Pu), and 3.8% ( Pu). 

With the Purex process used in the treatment of the irradiated fuels, the final product will be a concentrated solution of plutonium nitrate (100 to 250 g Pu/liter). However, plutonium oxide (PuOa) has been adopted as the material for storage with a view to safety standards because of its characteristics (chemical stability, physical state, etc.) from the viewpoints of preparation, shipping, and storage.  

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As the recycled fuel composition approaches steady state after approximately four cycles (1), the heat and radiation associated with and Pu require more elaborate conversion and fuel fabrication facihties than are needed for virgin fuel. The storage, solidification, packaging, shipping, and disposal considerations associated with wastes that result from this approach are primarily concerned with the relatively short-Hved fission products. The transuranic... 

Uranium oxide [1344-57-6] from mills is converted into uranium hexafluoride [7783-81-5] FJF, for use in gaseous diffusion isotope separation plants (see Diffusion separation methods). The wastes from these operations are only slightly radioactive. Both uranium-235 and uranium-238 have long half-Hves, 7.08 x 10 and 4.46 x 10 yr, respectively. Uranium enriched to around 3 wt % is shipped to a reactor fuel fabrication plant (see Nuclear REACTORS, NUCLEAR FUEL reserves). There conversion to uranium dioxide is foUowed by peUet formation, sintering, and placement in tubes to form fuel rods. The rods are put in bundles to form fuel assembHes. Despite active recycling (qv), some low activity wastes are produced. 

A. B. Shuck and R. M. Mayfield, The Process Equipment and Protective Enclosures Designedfor the Fuel Fabrication Facility, Facility No. 350, ANL-5499, Argonne National Laboratory, Argonne, lU., 1956. 

The most important role of UO3 is in the production of UF4 [10049-14-6] and UF [7783-81-5], which are used in the isotopic enrichment of uranium for use in nuclear fuels (119—121). The trioxide also plays a part in the production of UO2 for fuel peUets (122). In addition to these important synthetic appHcations, microspheres of UO3 can themselves be used as nuclear fuel. Fabrication of UO3 microspheres has been accompHshed using sol-gel or internal gelation processes (19,123—125). FinaHy, UO3 is also a support for destmctive oxidation catalysts of organics (126,127). 

Plutonium compounds, 19 687-691 protection against, 19 702 Plutonium dioxide, 19 688—689 Plutonium fuel fabrication facilities, 17 547 Plutonium-gallium alloys, 19 683-684 Plutonium halides, 19 689-690 Plutonium hexafluoride, 19 689 Plutonium hydrides, 19 690 Plutonium ions... 

DeNeal, D.L., Historical Events Single Pass Reactors and Fuels Fabrication, DUN-6888, Douglas United Nuclear Inc., Richland, WA, 1970. 

AECL has evaluated some of the basic information and development requirements in some detail (24, 25) and has outlined the type of fuel recycle development program which would be required. It would involve research and development of thorium fuels and fuel fabrication methods, reprocessing, demonstration of fuel management techniques and physics characteristics in existing CANDU reactors and demonstration of technology in health, safety, environmental, security and economics aspects of fuel recycle. 

Enriched UF6 is processed into U02 powder at fuel fabrication facilities using one of several methods. In one process uranium hexafluoride is vaporized and then absorbed by water to produce uranyl fluoride, U02F2, solution. Ammonium hydroxide is added to this solution and ammonium diuranate is precipitated. Ammonium diuranate is dried, reduced, and milled to make uranium dioxide powder. The powder is pressed into fuel pellets for nuclear reactors. 

The tests on the detoxification and reclamation method have demonstrated the following advantages in reprocessing metal-bearing spent acids from nuclear fuel fabrication ... 

Stewart, T. L., and J. N. Hartley. 1985. Evaluation of Improved Chemical Waste Disposal and Recovery Methods for N Reactor Fuel Fabrication Operations 1984 Annual Report. PNL-5294 and UNI-3204, Pacific Northwest Laboratory, Richland, Washington. 

As discussed earlier, natural uranium is 0.72 atom % 235U, and the fuel used in light-water reactors is typically 3% 235U. This means the refined uranium must be enriched in the lighter 235 isotope prior to fuel fabrication. This can be done by a... 

Transuranic Waste Transuranic waste (TRU) results from fuel reprocessing and fuel fabrication facilities, the production of nuclear weapons, and the decommissioning of nuclear reactors or fuel cycle facilities. TRU includes clothing,... 

The uranium and thorium ore concentrates received by fuel fabrication plants still contain a variety of impurities, some of which may be quite effective neutron absorbers. Such impurities must be almost completely removed if they are not seriously to impair reactor performance. The thermal neutron capture cross sections of the more important contaminants, along with some typical maximum concentrations acceptable for fuel fabrication, are given in Table 9. The removal of these unwanted elements may be effected either by precipitation and fractional crystallization methods, or by solvent extraction. The former methods have been historically important but have now been superseded by solvent extraction with TBP. The thorium or uranium salts so produced are then of sufficient purity to be accepted for fuel preparation or uranium enrichment. Solvent extraction by TBP also forms the basis of the Purex process for separating uranium and plutonium, and the Thorex process for separating uranium and thorium, in irradiated fuels. These processes and the principles of solvent extraction are described in more detail in Section 65.2.4, but the chemistry of U022+ and Th4+ extraction by TBP is considered here. 

About two-thirds of the separated Pu are used in mixed oxide (MOX) fuel fabrication. 

After a peak at 2010, the amount of Pu stored is supposed to start decreasing due to the expected increase in MOX fuel fabrication and its usage in Light Water Reactors (LWRs). Obviously, the utilization of MOX fuel by LWRs would gradually reach a balance in which the fissile Pu in the LWR fuel is ca. 5% of the total fuels. Consequently, the utilization of U resources would not be drastically improved. The ultimate utilization will be attained in the Fast Breeder Reactor (FBR) fuel cycle, in which a conversion of fertile 238U to 239Pu overwhelms the consumption of the 239Pu. 

The contamination due to 232U in the recovered 233U product leads to intense gamma radiation, which requires specially designed shielded facilities during fuel reprocessing and fuel fabrication. 

After feed acidity adjustment, plutonium and neptunium are recovered in the NPEX process, with high yields and sufficiently low impurity levels to make them suitable for MOX fuel fabrication. 

In the past ten years the number of chemistry-related research problems in the nuclear industry has increased dramatically. Many of these are related to surface or interfacial chemistry. Some applications are reviewed in the areas of waste management, activity transport in coolants, fuel fabrication, component development, reactor safety studies, and fuel reprocessing. Three recent studies in surface analysis are discussed in further detail in this paper. The first concerns the initial corrosion mechanisms of borosilicate glass used in high level waste encapsulation. The second deals with the effects of residual chloride contamination on nuclear reactor contaminants. Finally, some surface studies of the high temperature oxidation of Alloys 600 and 800 are outlined such characterizations are part of the effort to develop more protective surface films for nuclear reactor applications. ... 

Radioactive wastes of concern include wastes that result from operation of the nuclear fuel cycle (mining, fuel fabrication, reactor operation, spent fuel reprocessing, and waste storage), from nuclear weapons testing, and from medical and research activities. In recent years, the emphasis has been on predicting the behavior of disposed high-level wastes in deep geologic... 

The United States will probably need three fuel cycle centers. Each would include a reprocessing plant, an advanced fuel fabrication facility, and a waste glassification and storage facility. 

One kilogram of fuel provides 360 mWh of electrical energy (1.22 gBtu). To obtain 1 kilo of fuel requires 9 kilos of uranium. The cost of conversion, enrichment, and fuel fabrication results in a total cost of about 4,000/kg. Therefore, the fuel cost is 1.1c/kWh or 3.22/mBtu. 

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