The radiation impact on the environment from naturally-occurring radioactive materials in zircon sand is an important issue for zirconium product manufacturing enterprises. In this paper, a typical oxychloride production enterprise has been taken as an example to study the radiation effect and environmental pollution during the whole production process. The transfer and enrichment of radionuclides in zircon sand was studied by analyzing their concentrations in samples, such as products and wastes, which were sampled from every studied workshop, so that the dose rate in the environment and typical facility surfaces of each workshop could be measured. The study results show that the transfer and enrichment of radionuclides occur mainly in workshops of acidification, dissolution, concentration and crystallization. Silicon slag adsorbed some radionuclides, but most of the radionuclides in raw materials are transferred and enriched in waste acid by the concentration and crystallization process. Sludge and wastewater still contain a large quantity of radionuclides after treatment by wastewater treatment plants. This results in a significant increase in U-238 and Th-232 concentrations in river water near the main outlet. The average effective dose of all employees in the studied enterprises was 0.94 mSv, and workers from the wastewater treatment plants had the largest annual effective dose at 11 mSv.

We report the γ-ray ionizing radiation response of commercial off-the-shelf (COTS) monolithic active-pixel sensors (MAPS) with different integration times and gains. The distribution of the eight-bit two-dimensional matrix of MAPS output frame images was studied for different parameter settings and dose rates. We present the first results of the effects of these parameters on the response of the sensor and establish a linear relationship between the average response signal and radiation dose rate in the high-dose rate range. The results show that the distribution curves can be separated into three ranges. The first range is from 0 to 24, which generates the first significant low signal peak. The second range is from 25 to 250, which shows a smooth gradient change with different integration times, gains, and dose rates. The third range is from 251 to 255, where a final peak appears, which has a relationship with integral time, gain, and dose rate. The mean pixel value shows a linear dependence on the radiation dose rate, albeit with different calibration constants depending on the integration time and gain. Hence, MAPS can be used as a radiation monitoring device with good precision.