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AQUEOUS PROCESSING OF THORIUM FUELS.
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DOWNLOAD EBOOK →The status of aqueous processing methods for thorium fuels is summarized, with principal emphasis on the stainless steel-clad ThO2UO/sub 2/ type. Data were obtained principally from laboratory-scale experiments with fully irradiated fuel samples and engineering-scale tests with unirradiated fuel. Stainless steel cladding was easily dissolved with 4 to 6M H2SO4 (Sulfex process) or 5M HNO3-2M HCl (Darex process) in LCNA (Nionel type) or titanium equipment, respectively, in semicontinuous or batch equipment. Uranium losses to the decladding solutions were approximates 0.3% and 3 to 5% for the Sulfex and Darex processes, respectively, with fuel irradiated to approximates 20,000 Mwd/ton of core. The uranium was readily recovered from the Darex decladding solution in the acid Thorex extraction process. The ThO2UO/sub 2/ core was dissolved in 13M HNO3 -0.04M NaF-0.1M Al(NO3)sub 3/. Uranium and thorium can be recovered from graphite-base fuels by disintegration and leaching with 90% HNO3, grinding and leaching with 70% HNO3, or combustion followed by dissolution in fluoridecatlyzed nitric acid. Uranium and thorium were recovered from nitric acid solutions and separated from fission products by extraction with 30% tributyl phosphate in Amsco in the acid Thorex process. The use of an acid deficient feed (0.15M a.d.) induced high decontamination while injection of nitric acld at the fourth extraction stage provided high salting strength and ensured quantitative uranium and thorium extraction. Extensive studies with other organophosphorous extractants established the relations between metal extraction, radiation stability, and metal complex solubility with P-C or P-O bonding and chain branching. Di-sec- butyl phenylphosphonate (DSBPP) combined many of the advantages found and is applicable to the separation of uranium from thorium fission products. Since the thorium distribution coefficients (or Th/F.P. separation factors) were low, none of these extractants is potentially useful for recovery and decontamination of both thorium and uranium. (auth).
AQUEOUS PROCESSING OF THORIUM FUELS.
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Published: 1962
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DOWNLOAD EBOOK →The status of aqueous processing methods for Th fuels is reviewed. A specially designed 320 ton shear was successfully tested for chopping full size simulated Consolidated Edison type unirradiated assemblies into 0.25-1.5 in. lengths. Pieces about 0.5-in. long are preferred since the core pellets are more severely crushed during the chopping operation, and consequently, the rate of core dissolution is enhanced. The Darex (dtlute aqua regia) and Sulfex (4 to 6 M sulfuric acid) processes for dissolution of stainless steel claddings were developed on a small engineering scale with unirradiated fuel. In hot cell tests on stainless steel clad ThO2-UO2 fuel pins irradiated up to 22,000 Mwd/ton of fuel, the core pellets were severely fractured and losses of U and Th to the Sulfex and Darex solutions were approximates 0.3% and 3 to 5%, respectively. The latter losses are easily recovered in the extraction system. U and Th can be recovered from graphite base fuels by burning and dissoiution of the ash in HNO3 or by grinding to approximates 200 mesh followed by HNO/sub 3/ leaching. The Acid Thorex extraction process was developed to recover both U and Th using tributyl phosphate (TBP) as the solvent and the Acid Interim 23 process to recover only the U using either TBP or disecbutyl phenyl phosphate as the solvent. The Acid'' processes use HNO3 rather than Al as the salting agent. (auth).
Aqueous Processing of Thorium Fuels
Thorium Fuel Cycle
Recent Developments in Thorium Fuel Processing
Thorium Fuel Cycle
Author: International Atomic Energy Agency
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Published: 2005
Total Pages: 120
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DOWNLOAD EBOOK →Provides a critical review of the thorium fuel cycle: potential benefits and challenges in the thorium fuel cycle, mainly based on the latest developments at the front end of the fuel cycle, applying thorium fuel cycle options, and at the back end of the thorium fuel cycle.
Fundamental Studies on Nuclear Fuel Element Processing by Aqueous Methods in Sulphate Media
Reference Thorium Fuel Cycle
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Published: 1977
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DOWNLOAD EBOOK →The purpose of this report is to define a preliminary thorium fuel cycle to serve as a common basis for beginning development work on October 1, 1977, at participating ERDA laboratories, universities, and commercial facilities. Characteristics of the reference fuel cycle for the Thorium Fuel Cycle Technology (TFCT) program are: fissile uranium will be denatured by mixing with 238U; chemical processing plant design will be based on the assumption that plants are located in secure areas; plutonium will be recycled within these secure areas; thorium will be recycled with recovered uranium and plutonium; the head end of the chemical processing plant will handle a variety of core and blanket fuel assembly designs for light water reactors and heavy water reactors; the fuel form will be a homogeneous mixture of uranium and thorium oxide powders pressed into pellets; fuel cladding will be Zircaloy; and MgO will be added to the fuel to improve the thorium dissolving characteristics. (LK).
Thorium Fuel Cycle
