| 1. |
- Jerndal, Erik, 1980, et al.
(författare)
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Using Low-Cost Iron-Based Materials as Oxygen Carriers for Chemical Looping Combustion
- 2011
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Ingår i: Oil and Gas Science and Technology. - : EDP Sciences. - 1294-4475 .- 1953-8189. ; 66:2, s. 235-248
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Tidskriftsartikel (refereegranskat)abstract
- In chemical looping combustion with solid fuels, the oxygen-carrier lifetime is expectedto be shorter than with gaseous fuels. Therefore, it is particularly important to use low-cost oxygencarriers in solid fuel applications. Apart from being cheap, these oxygen carriers should be able toconvert the CO and H2 produced from the solid fuel gasification and be sufficiently hard to withstandfragmentation. Several low-cost iron-based materials displayed high conversion of syngas and highmechanical strength and can be used for further development of the technology. These materials includeoxide scales from Sandvik and Scana and an iron ore from LKAB. All tested oxygen carriers showedhigher gas conversion than a reference sample, the mineral ilmenite. Generally, softer oxygen carrierswere more porous and appeared to have a higher reactivity towards syngas. When compared withilmenite, the conversion of CO was higher for all oxygen carriers and the conversion of H2 was higherwhen tested for longer reduction times. The oxygen carrier Sandvik 2 displayed the highest conversion ofsyngas and was therefore selected for solid fuel experiments. The conversion rate of solid fuels washigher with Sandvik 2 than with the reference sample, ilmenite.
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| 2. |
- Bauhn, Lovisa, 1981, et al.
(författare)
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A micro hot test of the Chalmers-GANEX extraction system on used nuclear fuel
- 2013
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Ingår i: International Nuclear Fuel Cycle Conference, GLOBAL 2013: Nuclear Energy at a Crossroads. ; 1, s. 335-340
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Konferensbidrag (refereegranskat)abstract
- In the present study, a "micro hot test" has been performed using the Chalmers-GANEX (Group ActiNide EXtraction) system for partitioning of used nuclear fuel. The test included a pre-extraction step using N,N-di-2- ethylhexylbutyramide (DEHBA) in n-octanol to remove the bulk part of the uranium. This pre-extraction was followed by a group extraction of actinides using the mixture of TBP and CyMe4-BTBP in cyclohexanone as suggested in the Chalmers-GANEX process, and a three stage stripping of the extracted actinides. Distribution ratios for the extractions and stripping were determined based on a combination of γ- and α-spectrometry, as well as ICP-MS measurements. Successful extraction of uranium, plutonium and the minor actinides neptunium, americium and curium was achieved. However, measurements also indicated that co-extraction of europium occurs to some extent during the separation. These results were expected based on previous experiments using trace concentrations of actinides and lanthanides. Since this test was only performed in one stage with respect to the group actinide extraction, it is expected that multi stage tests will give even better results.
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| 3. |
- Hedberg, Marcus, 1987
(författare)
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Nitride fuel production by the internal sol gel process
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- AbstractDuring operation of a fourth generation reactor system it is necessarily not desirable to utilize an oxide fuel matrix as in light water reactor systems. One type of chemical compounds that has been suggested is nitride based nuclear fuel. Nitride fuels possess several characteristics that make them interesting for reactor operation such as high melting point, high thermal conductivity and better chemical compatibility compared to oxides with liquid metal coolants such as sodium or lead. Nitride fuel can be produced either as pure actinide nitride fuel such as UN or as fuel where the fissile material is diluted in an inert matrix such as (Zr, Pu)N. A problem with nitride fuel is the production process. Nitrides are not stable in air and production must thus be performed under inert atmosphere to reduce oxygen uptake in the material. Also residual oxygen and carbon content from production and processing is an issue that needs to be addressed. Spontaneous oxidation in air together with radiological safety concern regarding handling fine powders of actinide nitrides such as PuN for example provides an incitement for evaluating potential dust free processes for nitride fuel production. Work has been performed on production of ZrN as an inert fuel matrix by the internal sol gel process and subsequent carbothermal reduction. Elemental carbon suspension sols have been produced and gelled into microspheres. Heat treatments of the produced microspheres in N2 + 5 % H2 gas mixture was performed during nitridation. Elemental investigation of the produced microspheres suggested an approximate composition of Zr(N0.7 0.8C0.2 0.3). Pelletization of the nitride microspheres produced pellets with blackberry structure and XRD measurements on sintered material also suggested a material composition of about Zr(N0.8C0.2).Keywords: Nitride, ZrN, internal sol gel, carbothermal reduction, sintering
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