The Use of Fluidized Beds for the Continuous Drying and Calcination of Dissolved Nitrate Salts

Jonke, A.A.; Petkus, E.J.; Loeding, J.W.; Lawroski, S.

doi:10.13182/nse57-a25397

Cited by 24 publications

(4 citation statements)

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“…5 The reduction of this material to U02, followed by conversion to UF4, has been investigated by Tomlinson and coworkers.69 7 The present research R. M. DELL A N D V. J . WHEELER 1591 comprises an independent study of the reactivity of this type of UO3.…”

mentioning

confidence: 75%

“…(ii) At 520°C the rate of reduction of U308 is somewhat faster than that of the parent UO3. (5) The sigmoidal nature of the U03 reduction m e a has largely disappeared. The constant reduction rate for U3Oa samples prepared Qver a wide temperature range is at first sight surprising, having regard to the known sintering of U3Os at these temperatures 2 and the observed variable expansion of the particles during their preparations from UO3.…”

Section: Reduction Of U3o8 By Hydrogenmentioning

confidence: 99%

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Chemical reactivity of uranium trioxide. Part 1.—Conversion to U₃O₈, UO₂and UF₄

Dell¹,

Wheeler²

1962

Trans. Faraday Soc.

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A kinetic study has been made of the reduction of U03 to UOz by hydrogen and carbon monoxide and of the conversion of U02 to UF4 by hydrogen fluoride. The reduction reaction is an interfacial reaction proceeding via the UO2.6 phase, with CO reacting more readily than H2. The reactivity of UOz towards HF is a function of its surface area which increases with (a) lower reduction temperature, (b) the presence of sulphate impurity in the UO3.The decomposition of UO3 to U308 and conversion of the latter to UO;! and UFq has been studied also and the kinetics are reported. The rate of hydrofluorination of U02 prepared by this route is dependent upon the U03 decomposition temperature rather than upon the U3O8 reduction temperature. It is shown that for U02 to be reactive towards HF it must possess both an adequate surface area (> 2m2/g) and SUflEicient internal porosity to accommodate the volume increase associated with conversion to UF4.Some experiments on the interaction of U02 single crystals with HF are reported also.Uranium trioxide is known to form five different crystallographic phases (designated a-E) and an amorphous phase.1 The reduction of U03 to U02 by hydrogen and its subsequent conversion to UF4 by reaction with hydrogen fluoride are processes which have been studied extensively in the atomic energy industry, using principally yUO3 prepared from uranyl nitrate hexahydrate and #WOj prepared from ammonium diuranate. Both reactions are exothermic, viz., yU03(s) + H,(g)4J02(s)+ H20(g), AH&,* = -25.3 kcallmole, UO,(s) + 4HF(g)+UF4(s) +2H20(g), AH,",, = -432kcal/mole. A review of unpublished work has been compiled by Harrington and Ruehle.2 The reactivity of U02 towards " hydrofluorination " depends upon its physical properties (particle size, porosity, surface area, etc.) which, in turn, are governed by the kinetics of the reduction reaction and by the origin and structure of the UO3. U02 of widely differing reactivity may be prepared.The hydrogen reduction of U03 has been investigated recently by De Marco and Mendel 3 using high surface area (26 m2/g) amorphous U03 and by Notz and Mendel 4 using yU03 of surface area 3 m2/g. Reduction was found to take place in two distinct steps propagating sequentially, viz., u03+u02.6 and UO2.6-,Uo2. The intermediate UO2.6 phase is stable over a range of composition from u02.65 to u02.56 and loses oxygen progressively until, at the composition u02.56, u02 nucleates. Using high surface-area oxide, which can be reduced at low temperatures, it is possible to separate the two reactions completely ; with low surface-area U03 both reactions take place concurrently, the second reduction step lagging behind the first.Recently, interest has arisen in a type of yUO3 with an unusual and characteristic particle texture prepared by spray denitration of U02(N03)2.6H2O in a fluidized-bed reactor.5 The reduction of this material to U02, followed by conversion to UF4, has been investigated by Tomlinson and coworkers.69 7 The present research 1590

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mentioning

confidence: 75%

Section: Reduction Of U3o8 By Hydrogenmentioning

confidence: 99%

Chemical reactivity of uranium trioxide. Part 1.—Conversion to U₃O₈, UO₂and UF₄

Dell¹,

Wheeler²

1962

Trans. Faraday Soc.

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“…A mutual relation between microwave and materials handled in MH method is also very important parameter. The microwave absorption rate P of the dielectric is given by the following equation ' 7 ' : where P: Absorption rate (W /cm 3 ) f: Frequency of microwave (Hz) E: Electric field intensity (V /em) er: Relative permittivity tan o : Dielectric power factor.…”

Section: Stop Of Microwave Generation Tmentioning

confidence: 99%

Development of Microwave Heating Method for Co-Conversion of Plutonium-Uranium Nitrate to MOX Powder

Oshima¹

1989

Journal of Nuclear Science and Technology

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The development project of a conversion process using a microwave heating method (MH method) started in 1977. After basic experimental works, a co.conversion test unit was installed in the Plutonium Fuel Fabrication Facility (PFFF), PNC in 1979. The test unit had been operated to get engineering data of the MH method until 1984. During the operation of the test unit, the evaluation of the process and the characterization of the products powder have been performed.The data shows that MH process has many excellent advantages, such as good characteristics of the MOX product powder, good homogeneity of Pu-U in pellets, simplicity of the process, and a little liquid waste etc.Based on these data, the Plutonium Conversion Development Facility (PCDF) with the capacity of 10 kg Pu+U/d was designed and constructed beside the Tokai Reprocessing Plant.After a test operation in 1983, the PCDF has been operated quite smoothly without trouble. The products MOX powder has been supplied as a raw materials of fuels for the ATR "FUGEN" and the FBR "JOYO". Total quantity of the converted MOX powder was attained to about 4 t and over 50 t of MOX fuels have been fabricated and shipped to the reactor sites until July of 1988.Through the operations of the test unit in the PFFF and the PCDF, so many studies on MH method have been also performed and continuous denitration units are under development for the future technology.

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“…The values for similar-sized particles are in general higher than those observed in Figure 17, for which the starting material had a core of zirconium oxide. 6.…”

Section: Materials Without Zirconium Dioxide Corementioning

confidence: 99%

A Process for the Recovery of Uranium From Nuclear Fuel Elements Using Fluid-Bed Drying and Volatility Techniques

Levitz¹,

Barghusen²,

Carls³

et al. 1961

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The Use of Fluidized Beds for the Continuous Drying and Calcination of Dissolved Nitrate Salts

Cited by 24 publications

References 1 publication

Chemical reactivity of uranium trioxide. Part 1.—Conversion to U₃O₈, UO₂and UF₄

Chemical reactivity of uranium trioxide. Part 1.—Conversion to U₃O₈, UO₂and UF₄

Development of Microwave Heating Method for Co-Conversion of Plutonium-Uranium Nitrate to MOX Powder

A Process for the Recovery of Uranium From Nuclear Fuel Elements Using Fluid-Bed Drying and Volatility Techniques

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The Use of Fluidized Beds for the Continuous Drying and Calcination of Dissolved Nitrate Salts

Cited by 24 publications

References 1 publication

Chemical reactivity of uranium trioxide. Part 1.—Conversion to U3O8, UO2and UF4

Chemical reactivity of uranium trioxide. Part 1.—Conversion to U3O8, UO2and UF4

Development of Microwave Heating Method for Co-Conversion of Plutonium-Uranium Nitrate to MOX Powder

A Process for the Recovery of Uranium From Nuclear Fuel Elements Using Fluid-Bed Drying and Volatility Techniques

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Chemical reactivity of uranium trioxide. Part 1.—Conversion to U₃O₈, UO₂and UF₄

Chemical reactivity of uranium trioxide. Part 1.—Conversion to U₃O₈, UO₂and UF₄