Advanced Materials Research Vol. 772

Abstract: Spent nuclear fuel (SNF) from nuclear facilities such as from accumulated SNF commercial reactors becomes one of the important issues in term of reducing environmental impact and fuel sustainability as well as nuclear nonproliferation point of view when those SNF materials can be recycled and utilized as new fuel loaded into the reactors. Minor actinides (MA) as one of the important material of spent nuclear fuels can be recycled and transmuted into some useful materials which can be utilized to increase the fuel breeding capability as well as for increasing protected plutonium production from the view point of nuclear nonproliferation issue. Increasing some even mass isotopic plutonium compositions are estimated to increase the level of proliferation resistance level in term of material barrier point of view. The objective of this study is to analyze the proliferation resistance aspect of nuclear fuel based on plutonium production of different loading materials in the FBR blanket. Evaluation is based on some basic parameters of reactor operation analysis, such as reactor operation time which is adjusted to 800 days operation per cycle for 4 fuel batches systems which is refered to the large FBR type of Japan Sodium Fast Reactor (JSFR) design. The results show some nuclear fuels behavior during reactor operation for different loading materials and cycles. Minor actinide (MA) material loading as doping material gives some significant plutonium productions during reactor operation. Some obtained actinide productions have different profiles such as some reducing compositions in americium and neptunium actinide compositions with the time which depends on initial loading material. Some plutonium vector compositions are evaluated from Pu-238 to Pu-242 to estimate the proliferation resistance level as isotopic material barrier of plutonium. Some significant contributions for increasing even mass plutonium as plutonium protected material are shown by Pu-238 from all doping material as well as additional production of Pu-240 and Pu-242 in certain conditions.

Abstract: Nuclear fuel utilization program from front-end up to back-end processes especially spent fuel management have been monitored and safeguarded by the IAEA in order to ensure the utilization of nuclear fuels from all nuclear facilities including nuclear fuel reprocessing facilities are dedicated only for civil and peaceful purposes. Nuclear fuel production processes including reactor criticality condition is one of the major topics in term of nuclear fuel sustainability which related to energy security issues. Meanwhile, reduction level or preventing processes of nuclear fuel utilization from its potential risk from nuclear explosive purposes should be also strengthened and prioritized. To increase the intrinsic proliferation resistance of nuclear fuel, one of the potential ways is by increasing the material barrier level such as isotopic barrier. In case of plutonium, increasing the intrinsic properties of plutonium isotopes can be used by increasing material barrier of even mass number (Pu-238, Pu-240 and Pu-242). In this study, the effect of different irradiation process during reactor operation which related to discharged fuel burnup have been used and decay time to analyzed its dependeny to plutonium production as well as plutonium production dependency to decay or cooling time processes. Fuel production analysis of the reactor are based on the spent fuel of light water reactor (LWR) with different discharged fuel burnup (33 GWd/t, 50 GWd/t and 60 GWd/t) and different decay or cooling time process (1 to 30 years cooling time). Fuel behavior optimization of LWR design are obtained by using ORIGEN code by employing some modules for analyzing fuel production dependencies to burnup and decay time processes. In this study, two parameters for investigating the material barriers are adopted such as decay heat (DH) and spontaneous fission neutron (SFN) compositions. The compositions of DH and SFN are sensitive to the composition of isotopic plutonium especially more sensitive to even mass plutonium composition. Higher discharged fuel burnup level produces more even mass plutonium compositions and effectively reduce Pu-239 production because of more fissile Pu-239 are consumed for higher burnup. Isotopic Pu-238 gives the highest DH contributor, while Isotope Pu-240 obtains the highest contribution of SFN followed by other plutonium isotopes. DH and SFN compositions of plutonium can be increased effectively by increasing burnup process. Longer decay time is also effective to increase SFN compositions because of its dependency to all even mass plutonium while it gives less DH compositions because of its dependency to the contribution of Pu-238.

Abstract: We report our study of the safety analysis in design of small power reactor which design based on the concept of a long-life core reactor cooled by lead-bismuth eutectic (LBE). The motivation of these studies is in order to design a next generation of reactors, we need to design a type of reactor that has inherent safety. We designed the small Pb-Bi cooled reactor with MOX-Nitrate as a fuel. In order to study the safety analysis of this reactor we conducted studies of chimney length effect to coolant flow rate in natural circulation and dependency of outlet temperature with coolant flow rate. From this work we obtained the optimum height of chimney at 15 m for the lead-bismuth eutectic flow rate 3500 kg/s and also we found the dependency of outlet temperature with lead-bismuth eutectic flow rate.

Abstract: A small long-life core loaded with thorium fuel and ²³¹Pa as burnable poison material has been performed in Pressurized Water Reactor (PWR). Thorium cycle fuel has higher conversion ratio in the thermal spectrum domain and lower reactivity swing than the Uranium-Plutonium cycle fuel. ²³¹Pa have very large capture cross section that can pressed reactivity in the beginning of life. The neutronic analysis result of infinite cell calculation shows that mixed nitride is better than oxide and carbide in thorium fuel system. In the present study we consider thorium nitride system with 3 ~ 8 % ²³³U percentage and 0.2~ 7% ²³¹Pa as fuel for small PWR and can be burn up for the long time. The purpose of the study is to optimize the design of 350MWt PWR which can be operated without refueling in 10 years The core was designed by cylindrical two-dimension R-Z (radial and axial). The multigroup diffusion and Burn-up analysis was performed by SRAC-CITATION code using libraries based on JENDL 3.2. By using this concept, small PWR can be designed for long time operation with reduced excess reactivity until under 1 % and flatted power distribution during its operation.

Abstract: Design study of Pb-Bi cooled fast reactors with natural uranium as fuel cycle input using special radial shuffling strategy has been performed. The reactors utilizes UN-PUN as fuel, Eutectic Pb-Bi as coolant, and can be operated without refueling for 10 years in each batch. Reactor design optimization is performed to utilize natural uranium as fuel cycle input. This reactor subdivided into 6 regions with equal volume in radial directions. The natural uranium is initially put in region 1, and after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions. The calculation has been done by using SRAC-Citation system code and JENDL-3.2 library. The effective multiplication factor change increases monotonously during 10 years reactor operation time. There is significant power distribution change in the central part of the core during the BOC and the EOC. It is larger than that in the case of modified CANDLE case which use axial direction burning region move. The burnup level of fuel is slowly grows during the first 15 years but then grow fastly in the rest of burnup history. This pattern is a little bit different from the case of modified CANDLE burnup scheme in Axial direction in which the slow growing burnup period is relatively longer almost half of the burnup history.

Abstract: This study is aimed at examining environmental impacts of exhaust emissions imposed by various alcohol blending fuels. The tested fuels are 0%, 5%, 10%, 15% and 20% blending of methanol, ethanol or butanol alone. Rotation speeds of engine tests were controlled at 1500, 2500 and 3500 rpm to simulate slow, normal and fast speeds of vehicle driving. Gaseous emissions from engine exhaust were collected to determine the concentrations of CO, NO_x, HC, BTEX, formaldehyde and acetaldehyde. Most alcohol blending fuels were found able to lower regulated emission of CO, NO_x and HC as well as toxic constituents of BTEX more or less. Adversely, alcohol combustion in the engine could result in the formation of formaldehyde and acetaldehyde. Environmental impact on the release of formaldehyde should be aware and carefully controlled with the use of various alcohol blending fuels.

Abstract: A fuel injection system which is operated with ECU HILS was used to evaluate the transient fuel injection rate and fuel economy. Several sensor signals from a car such as the engine speed, car speed, cam position, crank position, air mass flow, throttle position and several other sensor signals are measured and recorded as a data file with DAQ-system for a vehicle driven in FTP-75 mode in a chassis dynamometer. Electric signals that are equivalent to the sensor signals from the car are reconstructed from the recorded data file using DAQ boards and a computer. All the reconstructed sensor signals are provided to the ECU with synchronized timing. Injectors were connected to the ECU output pins and were driven by the system to measure the quantity of injected fuel. The ECU HILS show that the transient fuel injection rate and fuel economy for the car driving mode could be successfully predicted. Also, the repeatability of the generation of sensor signals can enhance the accuracy of a range of experiments related to cars fuel injection experiment.

Abstract: Pure electric vehicles, as an important part of China's strategic emerging industries with good economical potential and ecological environment and social benefits, are increasingly becoming the strategic choice to response to global warming and to achieve low-carbon transformation of urban transport. Hangzhou pure electric taxi demonstration project is a model for new energy vehicles first try, which has formed the complete and operating norms for pure electric taxies operating system and business mode. Based on the typical research of Hangzhou pure electric taxi demonstration operation status quo, the research group has summarized the practical experience of the demonstration operations and some problems of the mode of development of pure electric vehicle battery and supporting facilities, and put forward some policy recommendations.

Abstract: In this paper, the insulated gate bipolar transistor (IGBT) is taken as an example to discuss the interference characteristics of the power electronics devices used in new energy vehicles. Firstly, the on-off processes of the IGBT are analyzed and reconstructed. Then, the high frequency circuit model of IGBT is established, considering both the on-off processes and the effects of the stray parameters. Furthermore, the effects of IGBT on equipment around are investigated based on the calculations of interference voltage transfer gains and common mode (CM) current transfer admittance. Finally, the model and analyses are verified by both the simulations and the experiments.

Abstract: Fluidized beds have been widely used in industrial processes. The inefficiency of current systems provides opportunities for improvement and development of new fluidized bed techniques. The swirling fluidized bed is an outcome of such a quest. The main shortcomings of present day SFB systems are the underutilization of available annular area and massing of bed particles at the periphery of the bed column. In this work the authors report the effect of increasing the annular area in a Swirling Fluidized Bed (SFB) by using longer blades for the distributor and compare it to the conventional blade length of 50 mm. Distributor blades of two different lengths, 50 mm and 100 mm, was used in this work and the bed height was measured with spherical bed particle of three different sizes (4 mm, 5 mm, 6 mm) at varying bed weight and superficial velocity. For a given bed weight, the benefits are achieved through a lower bed pressure drop as well as better quality of fluidization.