Reaction Mechanism of De-nitration of UO2(NO3)2 by the Microwave Heating

Kato, Yoshiyuki; Kurita, Tsutomu; Abe, Tomoyuki

doi:10.3327/taesj2002.4.77

Cited by 9 publications

(4 citation statements)

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“…The whole view of microwave oven installed inside the GB is shown in Figure 2. Details of the MH method have been presented in the previous papers [7][8] [9]. Obtained material by the de-nitration was calcined at 750 °C for two hours in the air, and then the oxide (U 3 O 8 -PuO 2 or U 3 O 8 ) was reduced to mixed dioxide or uranium dioxide at the same temperature under the N 2 -H 2 mixture gas.…”

Section: Samplesmentioning

confidence: 99%

Wet granulation of mixed oxide powders de-nitrated by the microwave heating

Kato

2012

Journal of Nuclear Science and Technology

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A performance in a wet granulation of MOX powders prepared by the microwave heating de-nitration method was examined to fabricate MOX fuel pellets for FBR at an extremely simplified process. An agitating granulator equipped with three blades and a chopper was used and its performance was evaluated. Characteristics and physical properties of the raw powder and the granules were measured together with observations by SEM before/after granulation. We could obtain the granules of 120 to 140 μm in diameter within a narrow range of water addition ratio 12.5 to 13.5 wt% combined with a flow-ability > 73 and a product yield > 90 %. Specific surface area that corresponds to sintering performance was almost the same as that of raw powder. When the ratio was < 9 wt%, no granule was observed, and flow-ability did not change from that of raw powder < 30. It was estimated from an additional experiment that the reason was capillaries (or voids) in the raw powder. When the ratio was more than 14 wt%, the flow-ability saturated and the product yield decreased. This narrow range of water addition ratio and strong binding force were successfully understood based on the standard theory of granulation supposing the Pendular state and the Gorge method.

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Section: Samplesmentioning

confidence: 99%

Wet granulation of mixed oxide powders de-nitrated by the microwave heating

Kato

2012

Journal of Nuclear Science and Technology

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“…Microwave radiation is the best heat source for the concentrating, drying, and oxidizing in the recycling of nuclear fuel. 63 One advantage of microwaves as the heat source is the rise of the effective temperature and the selective heating of the target materials. Such selective heating can extend the longevity of the nuclear reactor, and can lead to a decrease in maintenance time and costs.…”

Section: Environmental Remediation Using Microwave Dielectric Heatingmentioning

confidence: 99%

Novel designs of microwave discharge electrodeless lamps (MDEL) in photochemical applications. Use in advanced oxidation processes

Horikoshi

Abe

Serpone

2009

Photochem Photobiol Sci

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Novel light sources based on microwave discharge electrodeless lamps (MDEL) are examined as potential light sources to drive photochemical processes, in particular advanced oxidation processes (AOPs) of which various applications are described. The MDELs possess several features that make them attractive as possible environmental remediation lamps and as light sources to activate metal oxide photocatalysts in environmental remediation processes. Accordingly, the article describes some of the many features, albeit non-exhaustively, of MDEL devices and reports some photoreactors that incorporate these MDELs. Fundamental issues of MDEL light sources in remediation processing of actual pollutants are introduced. Examples are taken from the oxidative destruction of volatile organic compounds (VOCs; e.g. acetaldehyde and toluene), from the oxidative degradation of contaminants present in wastewaters (e.g. the 2,4-D herbicide and the endocrine disruptor bisphenol-A) and from the remediation of dioxin-contaminated fly-ash, along with an actual industrial wastewater sample from the manufacturing of cement.

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“…The density of UO 3 is lower (6.69 -8.62 g•cm ) depending upon the allotrope formed [57]. It was reported that the microwave denitration of uranyl nitrate produces β-UO 3 [55] [56]. The studies have shown that for denitration of uranyl nitrate, the crystal structure of the oxide product depend upon temperature and heating rate with desired porous product formed at faster heating rates [69].…”

Section: ) Effect Of Uo 2 In Thomentioning

confidence: 99%

An Integrated Process for Recycling of ThO<sub>2</sub> Based Mixed Oxide Rejected Nuclear Fuel Pellets

Singh¹,

Khot²,

Kumar³

et al. 2017

WJNST

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This paper presents a study on the process engineering aspects of relevance to the industrial implementation of ThO 2 and (Th, U)O 2 mixed oxide (MOX) pellet type fuel manufacturing. The paper in particular focuses on the recycling of thoria based fuel production scrap which is an economically important component in the fuel manufacturing process. The thoria based fuels are envisaged for Advanced Heavy Water Reactor (AHWR) and other reactors important to the Indian Nuclear Power Programme. A process was developed for recycling the chemically clean, off-specification and defective sintered ThO 2 and (Th, U)O 2 MOX nuclear fuel pellets. ThO 2 doesn't undergo oxidation or reduction and thus, more traditional methods of recycling are impractical. The integrated process was developed by combining three basic approaches of recycling namely mechanical micronisation, air oxidation (for MOX) and microwave dissolution-denitration. A thorough investigation of the influence of several variables as heating method, UO 2 content, fluoride and polyvinyl alcohol (PVA) addition during microwave dissolution-denitration was recorded on the product characteristics. The suitability evaluation of the recycled powder for re-fabrication of the fuel was carried out by analyzing the particle size, BET specific surface area, phase using XRD, bulk density and impurities. The physical and chemical properties of recycled powder obtained from the sintered (Th 1-y , U y )O 2 (y; 0 -30 wt%) pellets advocate 100% utilisation for fuel re-fabrication. Recycled ThO 2 by integrated process showed distinctly high sinterability compared to standard powder evaluated in terms of surface area and particle size.

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Reaction Mechanism of De-nitration of UO2(NO3)2 by the Microwave Heating

Cited by 9 publications

References 0 publications

Wet granulation of mixed oxide powders de-nitrated by the microwave heating

Wet granulation of mixed oxide powders de-nitrated by the microwave heating

Novel designs of microwave discharge electrodeless lamps (MDEL) in photochemical applications. Use in advanced oxidation processes

An Integrated Process for Recycling of ThO<sub>2</sub> Based Mixed Oxide Rejected Nuclear Fuel Pellets

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Reaction Mechanism of De-nitration of UO2(NO3)2 by the Microwave Heating

Cited by 9 publications

References 0 publications

Wet granulation of mixed oxide powders de-nitrated by the microwave heating

Wet granulation of mixed oxide powders de-nitrated by the microwave heating

Novel designs of microwave discharge electrodeless lamps (MDEL) in photochemical applications. Use in advanced oxidation processes

An Integrated Process for Recycling of ThO&lt;sub&gt;2&lt;/sub&gt; Based Mixed Oxide Rejected Nuclear Fuel Pellets

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An Integrated Process for Recycling of ThO<sub>2</sub> Based Mixed Oxide Rejected Nuclear Fuel Pellets