Uranium production

Domestic. Estimates of U.S. uranium resources for reasonably assured resources, estimated additional resources, and speculative resources at costs of 80, 130, and 260/kg of uranium are given in Table 1 (18). These estimates include only conventional uranium resources, which principally include sandstone deposits of the Colorado Plateaus, the Wyoming basins, and the Gulf Coastal Plain of Texas. Marine phosphorite deposits in central Elorida, the western United States, and other areas contain low grade uranium having 30—150 ppm U that can be recovered as a by-product from wet-process phosphoric acid. Because of relatively low uranium prices, on the order of 20.67/kg U (19), in situ leach and by-product plants accounted for 76% of total uranium production in 1992 (20). 

Uranium production in 1992 of 36,246 t U was only about 63% of world reactor requirements of 57,182 t U the remainder, 20,950 t U, was met from inventory drawdown. The worldwide production shortfall has developed since 1990 when production exceeded reactor requirements by about 1000 t U (27). 

World reactor-related requirements are expected to increase from 57,182 t U in 1992 to about 75,673 t U by the year 2010. Some utiUties are expected to continue to meet their requirements by purchasing or drawing on excess inventory. Annual uranium production should remain below actual requirements until some target level of stocks is reached (27). 

Supply Projections. Additional supphes are expected to be necessary to meet the projected production shortfall. A significant contribution is likely to come from uranium production centers such as Eastern Europe and Asia, which are not included in the capabihty projections (27). The remaining shortfall between fresh production and reactor requirements is expected to be filled by several alternative sources, including excess inventory drawdown. These shortfalls could also be met by the utili2ation of low cost resources that could become available as a result of technical developments or pohcy changes, production from either low or higher cost resources not identified in production capabihty projections, recycled material such as spent fuel, and low enriched uranium converted from the high enriched uranium (HEU) found in warheads (28). 

Once all technical and pohtical problems are resolved, reactor-grade uranium produced from HEU warhead material could contribute significantly to meeting the anticipated fresh uranium production shortfall. This source, however, is not expected to have a significant impact until the year 2000 or later. The discovery of new low cost resources is not expected to make a significant contribution to production until after the year 2005 because of the very low level of uranium exploration and the relatively long lead times required to develop new production centers (29). 

Uranium. The uranium product from the PUREX process is in the form of uranyl nitrate which must be converted to some other chemical depending on anticipated use. One route to MO fuel is to mix uranium and plutonium nitrates and perform a coprecipitation step. The precipitate is... 

About 9000 metric tons of sodium chlorate were used for uranium production during 1990 in North America. This usage was expected to decline sharply. Minor uses of sodium chlorate include the preparation of certain dyes and the processing of textiles (qv) and furs. 

The uses of Th are at present limited and only a few hundred tonnes are produced annually, about half of this still being devoted to the production of gas mantles (p. 1228). In view of its availability as a by-product of lanthanide and uranium production, output could be increased easily if it were to be used on a large scale as a nuclear fuel (see below). 

Uranium is found in most rock, in a concentration of two to four parts per million (ppm). Substantially greater average concentrations can be found in mineral deposits, as high as 10,000 ppm, or 10 percent. Most uranium deposits suitable for mining, however, contain an average of less than 1 percent uranium. Uranium is a metal, and thus its acquisition is not unlike the mining of any other metallic ore. Although uranium is found nearly eveiywhere on the earth, Canada leads the world in uranium production, mostly due to its heavy financial investment m uranium exploration, and to a few sizable deposits in the Saskatchewan territoiy. Table 1 depicts the total world uranium production in 1997. 

Since the uranium from the milling process is still in an unusable form, the yellow cake is broken down once again. The uranium trioxide is reduced to uranium dioxide at veiy high temperatures. Refining of the product also takes place. Now the uranium product consists almost entirely of UO,. 

Prices of other related goods also influence quantity supplied. For example, uranium production may produce vanadium as a byproduct. Thus, uranium and... 

Sandstone The tertiary, Jurassic and Triassic sandstones of the western Cordillera of the United States account for most of the uranium production in that country. Cretaceous and Permian sandstones are important host rocks in Argentina. Other important deposits are found in carboniferous deltaic sandstones in Niger in Permian Lacustrine siltstones in France and in Permian sandstones of the Alpine region. The deposits in Precambrian marginal marine sandstones in Gabon have also been classified as sandstone deposits. 

The last reaction cited above as shown is very effectively catalyzed by bacterial action but is very slow chemically by recycling the spent ferrous liquors and regenerating ferric iron bacterially, the amount of iron which must be derived from pyrite oxidation is limited to that needed to make up losses from the system, principally in the uranium product stream. This is important if the slow step in the overall process is the oxidation of pyrite. The situation is different in the case of bacterial leaching of copper sulfides where all the sulfide must be attacked to obtain copper with a high efficiency. A fourth reaction which may occur is the hydrolysis of ferric sulfate in solution, thus regenerating more sulfuric acid the ferrous-ferric oxidation consumes acid. 

Uranium production, 17 525-526 by country, 25 400t Uranium radioisotopes, 21 319 Uranium reactor fuel manufacture, hydrogen fluoride in, 14 19 Uranium recovery, ion-exchange resins in, 14 421-422... 

Uranium production does have a notable impact on ozone depletion. The Environmental Protection Agency s (EPA) Toxic Release Inventory showed that in 1999, the nation s two commercial nuclear fuel-manufacturing plants released 88% of the ozone-depleting chemical CFC-11 by industrial sources in the U.S. and 14% of the discharges in the whole world. 

Figure 4.3. Development of worldwide uranium production and demand (NEA/IAEA, 2006a).

Country Uranium production (t) Percentage of world production (%)... 

High-grade pitchblende ores are leached with nitric acid to recover uranium. Extraction of uranium from nitrate solutions is usually performed with TBP. TBP-based solvents are used in several areas of the nuclear industry, especially for reprocessing of spent nuclear fuels and for refining the uranium product of the Amex and Dapex processes. Extraction of uranium by TBP solvents is described in sections 12.3.4 and 12.5. 

Large-scale winning of copper by acidic leaching of copper ores sometimes results in waste solutions containing appreciable amounts of uranium. The uranium bearing aqueous raffinate from copper extraction is usually a dilute sulfuric acid solution. Uranium can be recovered using the same technique as described in section 12.3.1. A typical example is uranium production at the Olympic Dam mine in Australia, where the copper ore bodies are estimated to contain a total of over a million metric tons of uranium. 

Uranium stripping Dilute HNO3 solutions at 45-50°C are used to remove uranium from the TBP phase. Traces of the fission products ruthenium and zirconium are eliminated in the second and third cycles of the Purex process. Also, in the second and third cycles, neptunium and the last traces of plutonium are removed from the uranium product. 

Long-lived ty = 2.1 x 10 years) Tc, present as TCO4 in Purex process HNO3 feed solutions, is partially coextracted with uranium and plutonium in the first cycle. Unless separated in the Purex process, Tc contaminates the uranium product subsequent processing of the U02(N03)2 solution to UO2 can release some of the technetium to the environment. The presence of technetium in the purification steps as well as in the uranium product causes several other complications. Thus it is desirable to route all Tc into the high-level waste. Efforts in this direction have been described in some recent flow sheets [37]. 

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