[en] For comparing characteristics and accuracy of different methods, the simultaneous measurements of radon and thoron progeny were done using five-count filter method, two-count filter method and spectroscopy method in the Radon Key Lab of Hunan Province. Five-c ount filter method is more accurate than two-count filter method, however it is difficult to adopt five-count filter method for survey of environmental radon and thoron progeny in batches because of its longer measuring period (above 10 h) and more counts. The errors of two-count filter method are large in condition of concentration of thoron progeny higher than that of radon progeny. LCD-BWLM alpha spectroscopy method has some advantages such as simple operation, discrimination of a particles emitted from different nuclear, continuous measurement and so on, but the measurement results of thoron progeny are not reliable before measuring eight hours and under condition of variational thoron progeny. Filter must be hewed when the instrument is restarted. (authors)

[en] A method for superposing spectroscopy was developed and it can inquire simultaneously any energy span α spectroscopy of radon progeny and thoron progeny for any period. When measurement period was overlapped in an optimized α spectrum method for measuring radon progeny concentration and thoron progeny concentration in air the spectrum superposition method resolves this problem. So it can measure quickly and reliably radon progeny concentration and thoron progeny concentration in air on the ORTEC α spectroscopy workstation. (authors)

[en] Active carbon can decrease radon in local room because of its good capability with absorbing radon. The relations of the biggest decreasing radon efficiency with absorb coefficient, mass, volume of room, temperature, and humidity were studied. A theoretical model of decreasing radon efficiency by active carbon was established and verified with two sizes (4×8 mesh and 12×20 mesh) Philippine active carbon by the experiments. The result shows that the relative difference between theoretical value and measuring value is in ±4.7%. (authors)

[en] A method is introduced which had been used to measure radon and thoron concentration in thoron chamber by a scintillation cell, and gave two calculation methods which include a parallel arithmetic of concentration of ²²²Rn and ²²⁰Rn and other arithmetic of eliminating interference of ²²⁰Rn progeny to radon. Radon and thoron were measured in three different static time of 10, 15, 20 minutes respectively by a scintillation cell method and measured by RAD7 simultaneously. Measurement data of tow method were compared and analyzed. The results show a scintillation cell method is reliable and able to be used for rapid and accurate measurement, besides selecting static time 10 minutes and using parallel arithmetic is more reasonable, the measurement results are more reasonable than other situation. (authors)

[en] It is necessary to establish a reference atmosphere in a thoron chamber containing various ratios of ²¹²Bi to ²¹²Pb activity concentrations (C(²¹²Bi)/C(²¹²Pb)) to simulate typical environmental conditions (e.g., indoor or underground atmospheres). In this study, a novel method was developed for establishing and controlling C(²¹²Bi)/C(²¹²Pb) in a thoron chamber system based on an aging chamber and air recirculation loops which alter the ventilation rate. The effects of main factors on the C(²¹²Bi)/C(²¹²Pb) were explored, and a steady-state theoretical model was derived to calculate the ratio. The results show that the C(²¹²Bi)/C(²¹²Pb) inside the chamber is mainly dependent on ventilation rate. Ratios ranging from 0.33 to 0.83 are available under various ventilation. The stability coefficient of the ratios is better than 7%. The experimental results are close to the theoretical calculated results, which indicates that the model can serve as a guideline for the quantitative control of C(²¹²Bi)/C(²¹²Pb). - Highlights: • A novel method was developed for controlling C(²¹²Bi)/C(²¹²Pb) in thoron chambers. • A theoretical model was derived for calculating C(²¹²Bi)/C(²¹²Pb). • The coefficient of variation for C(²¹²Bi)/C(²¹²Pb) stability was less than 7%. • Effects of main factors on C(²¹²Bi)/C(²¹²Pb) were explored. • Various C(²¹²Bi)/C(²¹²Pb) were easily controlled.

[en] The experiment was completed in the Laboratory of radon university which can regulate temperature, humidity and radon concentration in radon chamber. In the experiment, we measured ²²⁰Rn,²²²Rn by CR-39SSNTD in different humidity. and analyzed the influence of humidity for the results. The results show that the detected efficiency of ²²²Rn was biggest and the standard deviation is 2.0% when the humidity is 50% from 35% to 95%. the detected efficiency of ²²⁰Rn reached the minimum and the standard deviation is 78.4% when the humidity is 75% from 30% to 100%. (authors)

[en] A process for treating low radioactive uranium wastewater by ultrasonic combined flocculation and precipitation has been developed and optimized. By using arsenazo III spectrophotometry to detect the mass concentration of uranium ions, the optimal coupling mode of ultrasonic flocculation and the optimal values of pH value, flocculant dosage, and ultrasonic power were obtained through single factor experiments. The conclusion drawn is that the optimal coupling method is to first add flocculants, then treat the solution with ultrasound, and finally stir the solution. The optimal values for each single factor are: the initial pH value of the solution is 9, the dosage of flocculant is 80 mg/L, and the sound energy density is 0.36 W/ml.The Box Behnken response surface experiment was designed using Design-Expert software. After completing the response surface experiment, a regression model for uranium ion removal rate was obtained. The highest uranium ion removal rate under theoretical conditions was obtained by solving the model.The predicted values of uranium ions removal rate of 95.68% was obtained with an acoustic energy density of 0.436 W/ml and a flocculant dosage of 88 mg/L at pH 9.It was observed that the actual experimental data under the same conditions are 95.41% The order of the influence factors of each process parameter on the uranium ion removal rate is: pH > flocculant dosage > ultrasonic power. Among them, there was a significant interaction between ultrasonic power and flocculant dosage. (author)

[en] A method has been developed for the simultaneous measurement of radon ("2"2"2Rn) and thoron ("2"2"0Rn) in a mixed environment using a scintillation cell in this paper. The method uses counts from two arbitrary counting intervals from zero time with respect to sampling, establishes two equations with two unknown variables to solve concentrations of radon and thoron, hence, called two-count method (TCM). The method can be used to estimate the radon and thoron concentrations in a mixed environment accurately and quickly , as there is no need to delay the counting to achieve complete decay of thoron. (authors)

[en] From the atomic scale, using the modified analytical embedded atom potential combined with the molecular dynamics simulation to study the point defects of radiation damage in FeCr alloy, the bind energy and the formation energy about various kinds of point defects in alloy have been calculated. The results show that, in FeCr alloy, the bind energies of first-nearest neighbor of vacancy with Cr was minimum (about 60 meV), in self-interstitial atoms, the <1111> Fe-Cr configuration have the lowest energies will be the most stable. (authors)

[en] The aim of this study is to improve and simplify the measurement of radon exhalation rate using the closed-loop accumulation method. Based on the ²²²Rn concentration data obtained from reference the standard module of uranium ore sands and cement, this work simplifies the ²²²Rn concentration growth model for calculating radon exhalation rate using the least squares method and proves its accuracy. Through fitting residual analysis, anomalies are screened at the significance level of α = 0.05 to enhance fitting precision. Herein, the influence of the starting point on the fitting effect and the calculation of radon exhalation rate is explored. The results indicate that after screening anomalous data, the fitting effects of the two sets of experimental data are further improved, and the relative errors in radon exhalation rate measurements are reduced from 1.77 to 1.41% and 13.08 to less than 10% respectively. (author)