Nuclear fuel , spent

Hafnium neutron absorption capabilities have caused its alloys to be proposed as separator sheets to allow closer spacing of spent nuclear fuel rods in interim holding ponds. Hafnium is the preferred material of constmction for certain critical mass situations in spent fuel reprocessing plants where hafnium s excellent corrosion resistance to nitric acid is also important. 

Spent nuclear fuel has fission products, uranium, and transuranic elements. Plans call for permanent disposal in underground repositories. Geological studies are in progress at the Yucca Mountain site in Nevada. Until a repository is completed, spent fuel must be stored in water pools or in dry storage casks at nuclear plant sites. 

Nuclear Waste. NRC defines high level radioactive waste to include (/) irradiated (spent) reactor fuel (2) Hquid waste resulting from the operation of the first cycle solvent extraction system, and the concentrated wastes from subsequent extraction cycles, in a faciHty for reprocessing irradiated reactor fuel and (3) soHds into which such Hquid wastes have been converted. Approximately 23,000 metric tons of spent nuclear fuel has been stored at commercial nuclear reactors as of 1991. This amount is expected to double by the year 2001. 

Approximately 25—30% of a reactor s fuel is removed and replaced during plaimed refueling outages, which normally occur every 12 to 18 months. Spent fuel is highly radioactive because it contains by-products from nuclear fission created during reactor operation. A characteristic of these radioactive materials is that they gradually decay, losing their radioactive properties at a set rate. Each radioactive component has a different rate of decay known as its half-life, which is the time it takes for a material to lose half of its radioactivity. The radioactive components in spent nuclear fuel include cobalt-60 (5-yr half-Hfe), cesium-137 (30-yr half-Hfe), and plutonium-239 (24,400-yr half-Hfe). 

HLW comprises most of the radioactivity associated with nuclear waste. Because that designation can cover radioactive waste from more than one source, the term spent nuclear fuel (SNF) will be used to discuss HLW originating from commercial nuclear reactors. LLW comprises nearly 90 percent of the volume of nuclear waste but little of the radioactivity. Nuclear power reactors produce SNF and most of the nation s LLW, although there are approximately 20,000 different sources of LLW. The name SNF is a bit of a misnomer because it implies that there is no useful material left in the fuel, when in fact some fissionable material is left in it. 

Besides fission products, the various forms of known but newly formed elements in the spent nuclear fuel, there is a small but significant amount of fissionable, or fissile, material in the SNF. This is quite important. There is some unused, unfissioned U-235 that has become too dilute to use. Like natural uranium ores in which chain reactions do not... 

U.S. Department of Energy. (1996) Integrated Data Base Report 1995 U.S. Spent Nuclear Fuel and Radioactive Waste Inventories, Projections and Characteristics, DOE/RW-0006, Revision 12. Washington, DC Author. 

Producers of electricity from nuclear power plants are assessed a fee of 0.1 cent per kilowatt-hour to pay for future storage of spent nuclear fuel at a federal facility. Receipts from this fee are allocated to the Nuclear Waste Trust Fund and arc appropriated by Congress to cover the costs of developing and constructing a permanent storage facility. 

In 1976 the Swedish government stipulated that no new nuclear reactors should be charged until it had been shown how the radioactive waste products could be taken care of in an "absolutely safe manner" (8). Consequently, the nuclear power industry (through their joint Nuclear Fuel Supply Co, SKBF) embarked on a program referred to as the Nuclear Fuel Safety (KBS) Project (8). In one of the schemes (9) a repository for spent nuclear fuel elements in envisaged at a depth of 500 m in granitic bedrock. The repository will ultimately contain 6000 tonnes of uranium and 45 tonnes of plutonium. The spent fuel elements will be stored in copper cylinders (0.8 m in diameter and 4.7 m in length) with a wall thickness of 200 mm the void will be filled with lead. 

Handling of Spent Nuclear Fuel and Final Storage of Vitrified High Level Reprocessing Waste" KambrSnslesakerhet Stockholm, 1977. 

Bond, W. Leuze, R. "Feasibility Studies of the Partitioning of Commercial High-Level Wastes Generated in Spent Nuclear Fuel Reprocessing Annual Progress Report for FY-1974," ORNL-5012, Oak Ridge, Tennesse, January 1975. 

Spent nuclear fuel remains radioactive and consists of a mixture of uranium... 

Before leaving ionic liquids it is worth mentioning their potential value in separation processes. Organic solvents are frequently used in multiphase extraction processes and pose the same problems in terms of VOC containment and recovery as they do in syntheses, hence ionic liquids could offer a more benign alternative. Interesting applications along this line which have been studied include separation of spent nuclear fuel from other nuclear waste and extraction of the antibiotic erythromycin-A. 

The effect of irradiation on the extractability of sulfoxides towards plutonium, uranium and some fission products were studied by Subramanian and coworkers . They studied mainly the effect of irradiation on dihexyl sulfoxide (DHSO) and found that irradiation did not change the distribution coefficient for Ru, Eu and Ce but increases the distribution coefficient for Zr and Pu. When comparing DHSO and tributyl phosphate (TBP), the usual solvent for the recovery and purification of plutonium and uranium from spent nuclear fuels, the effect of irradiation to deteriorate the extraction capability is much larger in TBP. Lan and coworkers studied diphenyl sulfoxides as protectors for the gamma radiolysis of TBP. It was found that diphenyl sulfoxide can accept energy from two different kinds of excited TBP and thus inhibits the decomposition of the latter. 

DOE. 1999. Inventory and characteristics of spent nuclear fuel high level radioactive waste and other... 

EPA, 1985, 40 CFR Part 191, Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes Final Rule, Federal Register 50, no. 182 38066. 

There has been considerable interest recently in the migration of long-lived nuclides involving technetium. The behavior of technetium in groundwater, sorption and permeation under subterranean conditions needs to be studied for the purpose of assessing environmental safety in connection with the disposal of spent nuclear fuel. Chemical and physicochemical data on technetium under such conditions are necessary. 

Countries and groups that lack access to nuclear weapons may still have opportunities to obtain radioactive materials such as spent nuclear fuel. A bomb in which a conventional explosive charge causes dispersal of radioactive material is known as a dirty bomb. Such a device could result in psychological effects exceeding the physical damage it caused. Once again, new techniques are needed for detection (of both the explosive and radioactive material), and decontamination procedures would be essential if such a device were used. 

Used in the manufacture of pharmaceuticals, dye intermediates, explosives, various inorganic and organic nitrates, nitro compounds and used industrially for ore flotation, metallurgy, photoengraving, and reprocessing spent nuclear fuel. 

By the year 2000, the United States will have an estimated 40,000 tons of spent nuclear fuel stored at some 70 sites and awaiting disposal. By 2035, after all existing nuclear plants have completed 40 years of operation, about 85,000 metric tons will be awaiting disposal (Slovic et al. 1991). 

Dose limits from spent nuclear fuel or transuranic radioactive wastes... 

Butex A process for separating the radioactive components of spent nuclear fuel by solvent extraction from nitric acid solution, using diethylene glycol dibutyl ether (also called Butex, or dibutyl carbitol) as the solvent. Developed by the Ministry of Supply (later the UK Atomic Energy Authority) in the late 1940s. Operated at Windscale from 1952 until 1964 when it was superseded by the Purex process. 

Purex [Plutonium and uranium recovery by extraction] A process for the solvent extraction of plutonium from solutions of uranium and fission products, obtained by dissolving spent nuclear fuel elements in nitric acid. The solvent is tri-n-butyl phosphate (TBP) in... 

Chemical textile finishing, 24 622 Chemical thermodynamics, of gas carburizing, 16 201-203 Chemical Transportation Emergency Center (CHEMTREC), 25 343 Chemical treatment of magnesium, 15 374 of spent nuclear fuel, 25 854 Chemical uses, for hydrogen peroxide,... 

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