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[en] On basis of overall description of changes of radon and its daughters' concentration in tunnels' airflow, some theoretical problems about air calculation, which should be considered, are discussed in this paper. These problems include the effects of non-uniform radon emanation, difference between the maximum and the mean radon daughters' alpha potential energy concentrations, air useful factors, effects of air allotment, use on the derived air concentration during determining air volume. The discussion includes not only the air calculating, but also the air control in underground uranium mines
[en] A method is given for calculating the concentration distribution of radon daughters in air-networks of uranium underground mine. Based on the measured air quantity, air pressure distribution, amount and volume of the released radon, the concentration distribution of radon daughters can be determined
[en] This paper mainly discusses a new idea about calculation formula of local static method as which is used to measure radon emanation rate from porous material, so as to be in keeping with practice. New formula given in this paper has considered four factors affecting radon building up in collecting space during measurement: emanation, reverse diffusion into porous material, leakage and radioactive decay. Equi-interval sampling method has been found out to make new formula easier to use. Experiment results indicate that the new formula tallies with practice much better than primary formula does
[en] Highlights: • A technical solution to the power supply of wireless sensor networks is presented. • The low voltage produced by TEG is boosted from less than 1 V to more than 4 V. • An output current and voltage of TEG device is acquired as 21.47 mA and 221 mV. • The device successfully provides output power 4.7 mW in no electricity conditions. • The thermo-economic value of TEG device is demonstrated. - Abstract: Motivated by the limited power supply of wireless sensors used to monitor the natural environment, for example, in forests, this study presents a technical solution by recycling solar irradiation heat using thermoelectric generators. Based on solar irradiation and the earth’s surface-air temperature difference, a new type of thermoelectric power generation device has been devised, the distinguishing features of which include the application of an all-glass heat-tube-type vacuum solar heat collection pipe to absorb and transfer solar energy without a water medium and the use of a thin heat dissipation tube to cool the earth surface air temperature. The effects of key parameters such as solar illumination, air temperature, load resistance, the proportional coefficient, output power and power generation efficiency for thermoelectric energy conversion are analyzed. The results of realistic outdoor experiments show that under a state of regular illumination at 3.75 × 10"4 lx, using one TEG module, the thermoelectric device is able to boost the voltage obtained from the natural solar irradiation from 221 mV to 4.41 V, with an output power of 4.7 mW. This means that the electrical energy generated can provide the power supply for low power consumption components, such as low power wireless sensors, ZigBee modules and other low power loads
[en] The average radon emanation rate of the whole surface over one year was used for evaluating the radon release of uranium tailings pile. The effective of radon protection cover depends on the shape and property of the tailings pile, the properties of covering and the control of air vadose in the pile. It was indicated that the covering with low diffusion coefficient, small porosity and bad permeability was suitable to cover the pile. The analytical formula of the covering layer thickness was given
[en] The enhanced modified simple equation method presented in this article is applied to construct the exact solutions of modified Benjamin-Bona-Mahoney equation. Some new exact solutions are derived by using this method. When some parameters are taken as special values, the solitary wave solutions can be got from the exact solutions. It is shown that the method introduced in this paper has general significance in searching for exact solutions to the nonlinear evolution equations. (authors)
[en] The sources of radon and the characteristics of radon emanation in uranium mines in China are discussed. Particular attention is directed to radon emanation that results from transport by air percolation (radon percolation for short), which exists widely in uranium mines. The emanation mechanism and the factors that influence radon percolation are considered and some relationships between percolation and ventilation based on test data are presented. The relationships demonstrate that ventilation not only dilutes the radon but also has the ability to control the rate of emanation. These findings have been reviewed, the principles and methods of radon control by ventilation are developed. (author)
[en] Highlights: • An approach is proposed to assess the influence of neutron activated products in BIXS method for tungsten based on Monte Carlo simulations. • Six principal radioactive neutron activated products (W-181, W-185, W-187, Ta-182, Re-186 and Re-188) with exhaustive decay data were included in the calculation to simulate the real condition. • W-187 strongly affects the tritium measurement shortly after DT experiments and about one month later W-181, W-185 and Ta-182 dominate the effects of neutron activated products. • The intensity of spectrum devoted by NAPs is as much as 10.6 times larger than by tritium in the same region of interest (ROI) directly after reactor shutdown, while it will reduce to 0.83% after 19 months. - Abstract: Tritium β-decay Induced X-ray Spectroscopy (BIXS) is a promising method to obtain tritium retention details both on surface and in bulk of plasma facing materials (PFMs) in magnetic fusion devices. Influence of neutron activated products (NAPs) is one of the primary problems in BIXS, since the energy of Compton scattering photons and characteristic X-rays is close to the range of tritium β-rays. In this paper, Monte Carlo simulation was introduced to evaluate effects of NAPs in BIXS measurements for tungsten. Three steps are included in simulation, neutron flux simulation to reckon the neutron flux in PFMs based on the simplified model of ITER, activated products calculation to compute the distribution of NAPs in PFMs and radiation spectra simulation to calculate the spectra of NAPs in PFMs sample. Six typical nuclides (including W-185, W-181 and Re-188, etc.) produced by neutron irradiation were considered in this study. Finally, influence of NAPs was estimated quantitatively with the assumption that 1% of DT fuel retained in PFMs uniformly. It is found that the intensity of spectrum devoted by NAPs is as much as 10.6 times larger than it by tritium in the same region of interest (ROI) directly after reactor shutdown, while it will reduce to 0.83% after 19 months.
[en] Conditioning effect on several kinds of optical substrates and film components by quasi-CW laser was investigated. Many samples showed absorption decreasing curves (ADC) under 532 nm and 355 nm irradiation, while keeping absorption values under 1064 nm irradiation. A phenomenological model was built to understand ADC. The model was based on that ADC should be mainly related to accumulated irradiation energy density. According to the model, the head part of ADC was influenced more by mechanism of laser conditioning, and the tail part formed mainly from Gaussian Beam. Normalized ADC and normalized high-asymptote parameter were considered as two tools to make comparison among different curves and get some mechanism information by the model. The results of re-analysis experiment data supported the model, and indicated that the real curves were more like e model shape. (authors)
[en] Highlights: • An extraction system with cooling channels has been designed for HUST negative ion source. • Corresponding heat loads onto three grids has been used in thermo-mechanical analysis. • The analysis results could be very useful for driving the engineering design. - Abstract: Huazhong University of Science and Technology (HUST) is developing a small radio frequency negative ion source experimental setup to promote research on neutral beam injection ion sources. The extraction system for the negative ion source is the key component to obtain the negative ions. The extraction system is composed of three grids: the plasma grid, the extraction grid and the grounded grid. Each grid is impacted by different heat loads. As the grids have to fulfil specific requirements regarding ion extraction, beam optics, and thermo-mechanical issues, grid cooling systems have been included for ensuring reliable operation. This paper focuses on the thermo-hydraulic and thermo-mechanical design of the grids. Finite element calculations have been carried out to analyse the temperature and deformation of the grids under heat loads using the fluid dynamics code CFX. Based on these results, the cooling circuit design and cooling parameters are optimised to satisfy the grid requirements.