This website has been archived from TrainWeb.org/utahrails to TrainWeb.US/utahrails.
U238
Uranium is a very heavy radioactive metal named after the planet Uranus. It occurs naturally in over 150 minerals and is about as common in the Earth's crust as tin, tungsten and molybdenum.
The eastern and southeastern regions near the basin margins of the Green, Grand, and Colorado rivers in Utah contain deposits of uranium. In 1898 the Welsh-Lofftus Uranium and Rare Metals Company operated in Richardson, Grand County. The San Rafael deposits were found about fifteen miles southwest of the Green River; and in 1904 ore was located in Wayne County, southeast of the San Rafael Swell. Other areas where uranium was found were west of the La Sal Mountains, south of Richardson, at Mill Creek, north of Moab, at Cold Creek (twenty miles north of Price), and at Temple Mountain.
Market demands grew for vanadium and radium, which are found in uranium. By 1906 nearly 200 tons of uranium were mined annually in Colorado and Utah. World War I sharpened the demand, as vanadium was used as a steel-hardening agent, and radium found a use as an illumination agent for watch faces, compasses, gunsights, and airplane dials. Nearly all the known deposits were located in the United States, and the market demand was high.
Shifting trends affected and altered Utah's uranium industry. Production slowed during the 1921-22 depression. Of more permanent significance were the rich ore finds of radium in the Belgian Congo in 1923, and of vanadium in Peru. These countries came to dominate the market.
Between 1923 and 1940 the production of uranium in Utah and the West proved negligible. However, during the Cold War period of the 1950s and 1960s uranium again reigned as a "wonder metal." The uranium strikes of the 1950s created another "bonanza" period in Utah mining. Charles (Charlie) Steen reigned as the most well known of the uranium bonanza kings. His palatial home in Moab exemplified this newfound wealth; but Steen's fortunes also were affected by the economic downturns of the industry.
It's not difficult to see why uranium is such a powerful producer of energy, in comparison with other fuels.
Firewood produces 16 megajoules (MJ) of heat per kilogram (kg) of fuel. For black coal, the figure ranges from 13-30 MJ/kg, natural gas produces 39 MJ/kg and crude oil produces 45-46 MJ/kg. Uranium - in a light water reactor - produces 440,000 MJ/kg.
Streams which drain areas rich in uranium will carry a minute amount of dissolved uranium. It is also present in the ocean, at a concentration of about 0.0003 parts per million.
Naturally occurring uranium is made up of three isotopes - 99.28 per cent U238, 0.71 per cent U235 and 0.01 per cent U234, where the number represents the number of particles in the nucleus of the atom. Of the three isotopes, only U235 is fissionable - which means only it can be used in nuclear reactions.
In a one million kilowatt power station, 25 tons of uranium would produce as much electricity in a year as around 2.3 million tons of coal. The other advantage of uranium as a fuel, its advocates say, is that it creates far fewer waste products.
About one ton of high level radioactive waste (after reprocessing), as opposed to about seven million tons of gases - mostly carbon and sulphur dioxides - and around 150,000 tons of solids - including ash and sulphur.
But first, the uranium must be mined and milled. There are three methods by which uranium is mined - open cut, underground and in-situ leaching.
The ore is sent from the mine to a mill, usually nearby, where it is crushed and ground to a fine grain size. Grinding and mixing with water produces a slurry of fine ore particles suspended in water. This is then leached with either an acid or an alkali, causing the uranium to dissolve. Most other minerals in the ore reamin undissolved and are removed as "tailings".
The uranium is then recovered from the solution, eventually being dried to produce a yellow powder known as "yellowcake", U3O8. It is then heated to about 700ºC to produce a dark grey-green uranium oxide powder containing more than 98 per cent uranium oxide.
Most nuclear reactors require the uranium fuel to be enriched, but first it needs to be converted to a gas. This gas is then enriched to remove about 85 per cent of the U238, which cannot be used in the fission process. The enrichment process raises the percentage of the fissionable U235 from the natural level of 0.7 per cent to about four per cent.
The enriched uranium is then taken to a fuel fabrication plant where it is converted to uranium dioxide (UO2) powder and pressed into pellets. These are then inserted into tubes to form fuel rods, which are used in the core of the reactor.
In the reactor core, neutrons are fired at the U235 atoms, splitting the nucleus of each. This process releases heat and fires off spare neutrons, which split other atoms, causing a chain reaction. During the reaction, some of the U238 is turned into plutonium, and about half of this is also fissioned, providing about one third of the reactor's energy output.
The heat from the reaction is used to produce steam to drive a turbine and generate electricity.
Spent fuel removed from the reactor core is stored in ponds, usually located at the reactor site, where they are cooled, and their radioactivity is contained. Spent fuel still contains about 96 per cent of the original uranium, with the U235 reduced from four per cent to one per cent of this. The rest has been converted to waste products by the nuclear fission, and one per cent of the spent fuel is made up of plutonium.
The spent fuel is reprocessed, to separate the uranium and plutonium from the waste products. Recovered uranium is returned to the conversion plant where it is turned back into a gas, and then re-enriched.
The highly radioactive waste that is left after this process is solidified, then incorporated into Pyrex glass to immobilise it. The glass is then poured into steel canisters which each hold 400 kilograms of glass.
Currently, this waste is stored in the canisters, but no decision has yet been taken on what to do with it. The most widely accepted plan is to bury the waste deep underground inside the steel canisters, or to encapsulate it in corrosion resistant metals such as copper or lead.
For a very good photo site, click on the first link below.
Uranium Exploration, Mining, and Milling on the Colorado Plateau
Last Update 06/07/02
This page and its underlying code, © 2000-2002, Utah Rails. All rights
About Us | Contact Us | Advertise With Us | Sign up for our FREE e-Newsletter!
View Stats | Page updated: 05/26/2021 | Version 2023l21b | Links | ©2015-2024 Silver Rails
Support this website by joining the Silver Rails TrainWeb Club for as little as $1 per month. Click here for info.