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Experimental hydraulic study of a fluidized-bed reactor
05 Nuclear fuels (scientific, technical) was also considered. Additionally, flow reactor studies on HCN oxidation, which is an important NO/N20 precursor, with and without SO2 present were performed. It was shown that with increasing temperature or increasing oxygen concentration the emissions of NO increase. N20 emissions increase only slightly with increasing oxygen concentration and show a maximum around a bed temperature of 800°C. A mechanism of homogeneous catalysis operated by SO2 is considered responsible of free radicals (i.e. H, O, OH) recombination under fuel lean conditions. Thus higher SO2 levels increase the emissions of CO, while NO decreases significantly. Due to the reduced destruction by radicals and the lower selectivity in HCN oxidation towards NO, N20 emissions increase at higher temperatures. Apart from the homogeneous interaction between SO2 and NOx and N20 emissions, the addition of limestone has a significant effect due to heterogeneous catalysis at active C a t sites. So the selectivity of HCN and NH3 oxidation towards NO is increased in the presence of limestone. The homogeneous tests in the flow reactor confirm the results obtained in the laboratory-scale FB. SO2 inhibits the conversion of HCN and combustible gases (i.e. CH4, CO and H2). It increases the selectivity of HCN oxidation to N20 compared to NO, by changing the formation paths but also decreasing the N20 destruction by the O radical. Modelling results are generally in good agreement with the experimental results.
02/01462
Triboelectrostatic beneficlation of fly ash
Soong, Y. et al. Fuel, 2001, 80, (6), 879-884. Dry triboelectrostatic separations of fly ash derived from both coal combustion and the combustion of coal mixed with 10 wt% biomass were conducted. Two different types of triboelectrostatic separators parallel plate and Iouvered plate separators - were used for this study. It is found that the material of construction for the tribocharger in the louvered plate separator affects both the deposition pattern and the quantity of recovery of the separated products. The poor quality of separation for the biomass fly ash studied is probably due to the physical/chemical nature of the biomass fly ash which is significantly different from that of coal fly ash.
02/01463 Vapor-grown carbon fibers (VGCFs) Basic properties and their battery applications Endo, M. et al. Carbon, 2001, 39, (9), 1287-1297. Submicron vapour grown carbon fibres (VGCFs) obtained by a floating growth method were evaluated in terms of their microstructural development with heat treatment temperature (HTI'), physical properties of a single fibre and of the bulk state, and additional effects, such as the filler in the electrode of a lead-acid battery and a Li-ion battery system. Its desirable properties, such as relatively high mechanical strength and electrical conductivity, both in the single fibre state and in the bulk state, including their very special network-like morphology, improved the performance of the electrodes in lead-acid batteries and Li-ion batteries, especially their cycle characteristics.
02/01464
Vitrification of borate waste from nuclear power plant using coal fly ash. (I) Glass formulation development
Sheng, J. Fuel, 2001, 80, (10), 1365-1369. Borate waste, which is the main liquid waste from daily operation of PWR nuclear power plants, contains a large amount of Na and B. The coal fly ash is a by-product of the coal combustion power plants. The high content of SiO2 and A1203 of coal fly ash makes it a desirable glass network former additive; therefore, using the coal fly ash to vitrify the borate waste without other additives is of great interest from the view point of economic and environment. In this paper, the suitability for vitrifying borate waste using coal fly ash was evaluated. Upon to 40 wt% of borate waste oxides could be successfully vitrified. Glass with 30 wt% of borate waste and 70 wt% of fly ash contain no crystals and show good chemical durability and suitable viscosity. The coal fly ash is a promising material for use in the immobilization of borate waste.
05
N U C L E A R FUELS
This paper proposes an ALE (Arbitrary Lagrangian-Eulerian) finite element method for gas-liquid two-phase flow, based on an incompressible two-fluid model, to analyse the two-pha~ flow including moving boundaries. The basic equations are derived by describing the two-fluid model in the ALE form. The solution algorithm is parallel to a fractional step method, and the Galerkin method is employed for the formulation. A quadrilateral element with four nodes is used for the discrctization of the computational domain. The present method is also applied to calculate the flow around a circular cylinder, which is forced to oscillate in a quiescent air-water two-phase mixture. The drag coefficients of the cylinder exhibit periodical change in accordance with the variation of the flow around the cylinder. The time variations of the flow field and drag coefficients are discussed in relation to the oscillation of the cylinder. /
02/01466 Analysis of the fracture behavior of hydrlded fuel cladding by fracture mechanics Kuroda, M. et al. Nuclear Engineering and Design, 2001, 203, (2-3), 185-194. In order to elucidate the fracture behaviour of light water reactor (LWR) fuel rods under reactivity initiated accident (RIA) conditions, an analysis based on fracture mechanics has been performed for several types of hydrided cladding tubes. Fracture mechanics parameters such as stress intensity factor (SIF), J-integral and plastic yield load were estimated by finite element method (FEM) analysis, and the failure assessment diagram (FAD) was constructed using the fracture mechanics parameters to estimate the failure stress of the claddings. It was found from the FAD that the predicted fracture stress of the claddings was qualitatively consistent with the experimental results obtained by pulse irradiation tests in the Nuclear Safety Research Reactor (NSRR) and high-pressurization-rate burst tests at Japan Atomic Energy Research Institute (JAERI).
02/01467 Crack stability evaluation of nuclear main steam pipe considering load reduction effect Koh, B-H. et aL Nuclear Engineering and Design, 2001, 203, (2-3), 175184. The objective of this paper is to evaluate the crack stability of a nuclear main steam pipe, considering load reduction effect due to the presence of circumferential through-wall crack. Also, optimization techniques are adopted to simulate the crack effect on the elbow component of piping systems. By using a general beam element that contains a discontinuous cross-section, piping analysis is performed to obtain the reduced load. Considering this reduced load, LBB design concept is applicable to the nuclear main steam pipe system. Also, by combining an optimization program and a general finite element analysis software, the appropriate dimensions are simplified and an equivalent beam element representing the effect of crack in the elbow could be successfully obtained.
Direct energy generation and energy conservation in radiation shielding facilities 02/01468
Bakos, G.C. Annals o f Nuclear Energy, 2001, 28, (5), 513-518. In this paper, the experimental and theoretical calculation of direct heat generation from the penetration of 6.20 MeV photons energy through double layer combinations of concrete (AI), steel (Fe) and lead (Pb) shields is described. The results are displayed in curves to show the distribution of heat generation in the shield thickness. The results show good agreement between the measured and calculated values and show also that the heat generation has its maximum value in the first layer of the shield thickness.
02/01469 reactor
Experimental hydraulic study of a fluidized-bed
Souto, S.L.L. et al. Annals of Nuclear Energy, 2001, 28, (5), 503-508. This article reports the results of an experimental rig that was developed to study the bed fluidization in a fluidized-bcd nuclear reactor model by measuring bed porosity using gamma absorptiometry. This hydraulic study reveals some problems with the fluidized bed control resulting from the original design concept for some reactor components. As a consequence, the limiting screen and control ring will have to be redesigned, making possible the formation of a stable fluidization for fuel/moderator aspect ratio between 0.75 and 1.0.
Improved Los Ala~os modtl applied to the neutron Induced fission of ~°'Pu and " " P u and to the spontaneous fission of Pu isotopes 02/01470
Scientific, technical 02/01465 ALE finite element method for gas-liquid twophase flow including moving boundary based on an incompressible two-fluid model Uchiyama, T. et al. Nuclear Engineering and Design, 2001, 205, (1-2), 69-82.
188 Fuel and Energy Abstracts May 2002
Vladuca, G. and Tudora, A. Annals of Nuclear Energy, 2001, 28, (7), 689-700. The Los Alamos model with multiple fission chances upgraded with (a) the linear relation between the average prompt gamma ray energy and the average prompt neutron multiplicity and (b) the dependence of the average fission fragment kinetic energy on the incident neutron energy, is used for the n + 2 3 9 Pu and n + "-2~4°pu reactions, and also for the spontaneous fission of 237 - 241 Pu isotopes. In the case of 2 4°Pu fissioning
02/01462
Triboelectrostatic beneficlation of fly ash
Soong, Y. et al. Fuel, 2001, 80, (6), 879-884. Dry triboelectrostatic separations of fly ash derived from both coal combustion and the combustion of coal mixed with 10 wt% biomass were conducted. Two different types of triboelectrostatic separators parallel plate and Iouvered plate separators - were used for this study. It is found that the material of construction for the tribocharger in the louvered plate separator affects both the deposition pattern and the quantity of recovery of the separated products. The poor quality of separation for the biomass fly ash studied is probably due to the physical/chemical nature of the biomass fly ash which is significantly different from that of coal fly ash.
02/01463 Vapor-grown carbon fibers (VGCFs) Basic properties and their battery applications Endo, M. et al. Carbon, 2001, 39, (9), 1287-1297. Submicron vapour grown carbon fibres (VGCFs) obtained by a floating growth method were evaluated in terms of their microstructural development with heat treatment temperature (HTI'), physical properties of a single fibre and of the bulk state, and additional effects, such as the filler in the electrode of a lead-acid battery and a Li-ion battery system. Its desirable properties, such as relatively high mechanical strength and electrical conductivity, both in the single fibre state and in the bulk state, including their very special network-like morphology, improved the performance of the electrodes in lead-acid batteries and Li-ion batteries, especially their cycle characteristics.
02/01464
Vitrification of borate waste from nuclear power plant using coal fly ash. (I) Glass formulation development
Sheng, J. Fuel, 2001, 80, (10), 1365-1369. Borate waste, which is the main liquid waste from daily operation of PWR nuclear power plants, contains a large amount of Na and B. The coal fly ash is a by-product of the coal combustion power plants. The high content of SiO2 and A1203 of coal fly ash makes it a desirable glass network former additive; therefore, using the coal fly ash to vitrify the borate waste without other additives is of great interest from the view point of economic and environment. In this paper, the suitability for vitrifying borate waste using coal fly ash was evaluated. Upon to 40 wt% of borate waste oxides could be successfully vitrified. Glass with 30 wt% of borate waste and 70 wt% of fly ash contain no crystals and show good chemical durability and suitable viscosity. The coal fly ash is a promising material for use in the immobilization of borate waste.
05
N U C L E A R FUELS
This paper proposes an ALE (Arbitrary Lagrangian-Eulerian) finite element method for gas-liquid two-phase flow, based on an incompressible two-fluid model, to analyse the two-pha~ flow including moving boundaries. The basic equations are derived by describing the two-fluid model in the ALE form. The solution algorithm is parallel to a fractional step method, and the Galerkin method is employed for the formulation. A quadrilateral element with four nodes is used for the discrctization of the computational domain. The present method is also applied to calculate the flow around a circular cylinder, which is forced to oscillate in a quiescent air-water two-phase mixture. The drag coefficients of the cylinder exhibit periodical change in accordance with the variation of the flow around the cylinder. The time variations of the flow field and drag coefficients are discussed in relation to the oscillation of the cylinder. /
02/01466 Analysis of the fracture behavior of hydrlded fuel cladding by fracture mechanics Kuroda, M. et al. Nuclear Engineering and Design, 2001, 203, (2-3), 185-194. In order to elucidate the fracture behaviour of light water reactor (LWR) fuel rods under reactivity initiated accident (RIA) conditions, an analysis based on fracture mechanics has been performed for several types of hydrided cladding tubes. Fracture mechanics parameters such as stress intensity factor (SIF), J-integral and plastic yield load were estimated by finite element method (FEM) analysis, and the failure assessment diagram (FAD) was constructed using the fracture mechanics parameters to estimate the failure stress of the claddings. It was found from the FAD that the predicted fracture stress of the claddings was qualitatively consistent with the experimental results obtained by pulse irradiation tests in the Nuclear Safety Research Reactor (NSRR) and high-pressurization-rate burst tests at Japan Atomic Energy Research Institute (JAERI).
02/01467 Crack stability evaluation of nuclear main steam pipe considering load reduction effect Koh, B-H. et aL Nuclear Engineering and Design, 2001, 203, (2-3), 175184. The objective of this paper is to evaluate the crack stability of a nuclear main steam pipe, considering load reduction effect due to the presence of circumferential through-wall crack. Also, optimization techniques are adopted to simulate the crack effect on the elbow component of piping systems. By using a general beam element that contains a discontinuous cross-section, piping analysis is performed to obtain the reduced load. Considering this reduced load, LBB design concept is applicable to the nuclear main steam pipe system. Also, by combining an optimization program and a general finite element analysis software, the appropriate dimensions are simplified and an equivalent beam element representing the effect of crack in the elbow could be successfully obtained.
Direct energy generation and energy conservation in radiation shielding facilities 02/01468
Bakos, G.C. Annals o f Nuclear Energy, 2001, 28, (5), 513-518. In this paper, the experimental and theoretical calculation of direct heat generation from the penetration of 6.20 MeV photons energy through double layer combinations of concrete (AI), steel (Fe) and lead (Pb) shields is described. The results are displayed in curves to show the distribution of heat generation in the shield thickness. The results show good agreement between the measured and calculated values and show also that the heat generation has its maximum value in the first layer of the shield thickness.
02/01469 reactor
Experimental hydraulic study of a fluidized-bed
Souto, S.L.L. et al. Annals of Nuclear Energy, 2001, 28, (5), 503-508. This article reports the results of an experimental rig that was developed to study the bed fluidization in a fluidized-bcd nuclear reactor model by measuring bed porosity using gamma absorptiometry. This hydraulic study reveals some problems with the fluidized bed control resulting from the original design concept for some reactor components. As a consequence, the limiting screen and control ring will have to be redesigned, making possible the formation of a stable fluidization for fuel/moderator aspect ratio between 0.75 and 1.0.
Improved Los Ala~os modtl applied to the neutron Induced fission of ~°'Pu and " " P u and to the spontaneous fission of Pu isotopes 02/01470
Scientific, technical 02/01465 ALE finite element method for gas-liquid twophase flow including moving boundary based on an incompressible two-fluid model Uchiyama, T. et al. Nuclear Engineering and Design, 2001, 205, (1-2), 69-82.
188 Fuel and Energy Abstracts May 2002
Vladuca, G. and Tudora, A. Annals of Nuclear Energy, 2001, 28, (7), 689-700. The Los Alamos model with multiple fission chances upgraded with (a) the linear relation between the average prompt gamma ray energy and the average prompt neutron multiplicity and (b) the dependence of the average fission fragment kinetic energy on the incident neutron energy, is used for the n + 2 3 9 Pu and n + "-2~4°pu reactions, and also for the spontaneous fission of 237 - 241 Pu isotopes. In the case of 2 4°Pu fissioning