Advanced Materials Research Vols. 953-954

Abstract: The transient characteristics of induction generator (IG) were investigated in the paper, and the analytic formula of its stator current under three-phase short circuit in distribution network was derived. According to the change law of IG rotor speed under the grid fault, an evaluation method to determine the current peak of three-phase short circuit for induction generator in distribution grid is proposed. The correctness of the proposed method was verified by the fifth electromagnetic transient model of IG in PSCAD/EMTDC simulation software.

Abstract: This paper aims to put forward a wind power plant risk management model, using bayesian networks, not only suitable for the project risk management, also useful for subsequent projects. For other construction enterprise risk management problem has great reference value.

Abstract: The PV and wind hybrid power system uses the front-end DC-DC conversion circuit, the system's overall output power is unified deployment and controlled, through elaborating the component characteristics and assessing mathematical model of the actual obtained, more accurately determines operation condition of the system per hour. The system energy analysis of flow and motion makes the system in dynamic change switch from the different forms of work patterns and operation, completing the corresponding control, so as to realize the optimization of system and reliable operation.

Abstract: The chemical speciations of uranium of a sandstone uranium deposit in the Yili Basin were quantitative analyzed using the method of sequential chemical extraction, and the implications of which for in-situ leaching of uranium were discussed. The proportion of chemical speciations of uranium shows that the bound to carbonates>the bound to Fe-Mn oxides>the exchangeable>the residual>the bound to sulfide-organic matter speciation, which is beneficial to cost reduction on in-situ leaching of uranium and environmental protection. The active uranium includes 4 chemical speciations except for the residual speciation is principal, which suggests that the leaching rate of uranium of the sandstone uranium deposit is high. The inert uranium is the residual speciation, with low proportion. The sample with high proportion of active uranium is of high grade, and vice versa, which indicates that the ratio of total uranium extracted/reserves should be relatively high. Hence, based on the chemical speciations of uranium, the sandstone uranium deposit can be exploited suitably using the technique of in-situ leaching with dilute sulfuric acid, integrated considering that cost control of in-situ leaching of uranium, environmental protection, leaching rate of uranium and the ratio of total uranium extracted/reserves of uranium.

Abstract: The variations of secondary circuit parameters are limited by the parameters of primary circuit during PWR nuclear power station operation, the primary circuit average temperature should vary at the range of nuclear reactor operating safely. In the existing analysis of secondary circuit thermal efficiency at nuclear power station, the impact of primary circuit average temperature on the secondary circuit thermal efficiency is not taken into consideration. In this paper, the changes of primary circuit average temperature in actual operation are considered, the secondary circuit parameters are calculated according to the model of heat flux transfer between primary and secondary circuit, the thermal efficiency of ideal cycle is chosen as the evaluating indicator of secondary circuit thermal efficiency, the thermal efficiencies of ideal cycle in secondary circuit are calculated under the conditions of varying coolant average temperature with the method of matrix, and the calculated results are basis for the safe and economic operation of nuclear power station.

Abstract: The ORIGEN-S and ORIGEN2 codes were described in this paper, which were used to calculate the source term in the reactor core. The differences between ORIGEN-S and ORIGEN2 codes were compared and analyzed. The most significant difference was the methodology used to prepare and provide the neutron data for the codes, which directly affected the accuracy of calculation results of the ORIGEN2 code under different values of the parameters. Finally, the radioactivity of the actinide and fission products was calculated by changing the fuel enrichment, burnup and specific power of PWR, which was used to make quantitative analysis of the difference of results calculated by ORIGEN-S and ORIGEN2 and verify the degree of influence of various parameters on the results.

Abstract: The fuel salt of molten salt reactor is comprised of LiF-BeF₂-ThF₄-UF4, which can produce more tritium than PWR. Since tritium is an important radioactive nuclide, and it would cause great damage to the reactor, the process to control tritium from fuel salt is a key point in the operation of molten salt reactor. In this article, the source and control of gaseous tritium is mainly discussed.

Abstract: Through-diffusion and out-diffusion are good way to understand anion diffusion behavior in compacted bentonite. In the present work we investigated Re (VII) and Se (IV) diffusion behavior in 2000 kg/m³ compacted GMZ bentonite. The D_e values of Re (VII) and Se (IV) are 0.29 ± 0.02 and 0.77 ± 0.05× 10^-11 m²/s. The result obtained from out-diffusion method was not agreed with predicted data due to the heterogeneous porosity distribution in clay boundaries and species changed when the diffusion occurred in GMZ bentonite. Comparing the D_a values of Se, Tc and I in GMZ and Kunigel-F bentonites, it showed that Kunigel-F bentonite hindered the mobilities of anion more efficiently than GMZ bentonite because of the higher content of montmorillonite.

Abstract: In order to improve the inherent safety of the Molten Salt Reactor (MSR), a concept of passive residual heat removal system (PRHRS) for the 10MW Molten Salt Reactor Experiment (MSRE) was put forward. Its transient characteristics were investigated by developing a model of it using C++ code. The effects of environmental temperature, finned tube number and chimney height on the PRHRS were analyzed. The results show that the PRHRS can remove the decay heat timely. Three natural circulations are established in the PRHRS when it begins to operate. With the decay heat power reducing, the PRHRS can automatically adjust its heat removal ability. It needs not any external power for the PRHRS to operate, which enhances the inherent safety and reliability of the reactor, especially under the condition that power plants lose power.

Abstract: Lithium titanate (Li₂TiO₃) in form of packed pebble bed is promising concept for breeder material in the fusion reactor blanket, and worldwide efforts have been dedicated to its R&D in the last two decade. Li₂TiO₃ pebble beds with the efforts of tritium breeding and thermal removing play a major role in the thermal performance of the fusion reactor blanket. Specifically, the effective thermal conductivity of Li₂TiO₃ is an important parameter for the design and thermal mechanical of fusion reactor blanket. The theoretical calculation and numerical simulation for the effective thermal conductivity of Li₂TiO₃ pebble bed are performed in this paper. The theoretical equations and modeling result for the thermal conductivity of Li₂TiO₃ pebble bed are given and compared with the experimental data. The results show that the effective thermal conductivity of Li₂TiO₃ pebble bed can be preliminarily obtained by numerical simulation and theoretical calculation.