Spent fuel reprocessing is of great significance to the nuclear fuel cycle and the sustainable development of nuclear energy. At the same time, nuclear security radiation incidents in the spent fuel reprocessing plant are also related to national personal and property safety, which play a pivotal role. In this paper, the spent fuel reprocessing plant is divided into four plant areas: the main process area, the three-waste area, the auxiliary equipment area, and the pre-plant area, which are further subdivided into 12 evaluation units. The expert scoring method is used to score and evaluate the possibility of eight basic nuclear accident types in each area, namely radioactive dispersal device, computer nuclear security, destruction of nuclear facilities, transportation nuclear security, internal threat, potential threat, illegal transfer, and theft. According to the professional titles, length of service, education and other qualifications of experts, different weights are assigned to the experts. The scoring results are applied to the Fault Tree Analysis (FTA) of nuclear security events as the probability of basic events, so as to obtain the risk of each basic event. At the same time, the fuzzy comprehensive evaluation method and probability–mathematical statistics method are used to evaluate each evaluation unit to determine the risk of each evaluation unit and the plant area. There results show that the main process area has the highest risk degree, while the pre-plant area has the lowest risk degree, and there is a 1.5-fold relationship. This research provides theoretical and technical support for the safety management and operation of spent fuel reprocessing plants. The analysis results of this paper can be used as a reference for the proportion of nuclear security protection improvements in each plant area, so as to achieve an efficient safety protection effect. The research method in this paper can be also applicable to other similar places by providing as input the corresponding probability of occurrence to obtain the index of its risk degree, so as to reasonably allocate funds and manpower and reduce risks.

In this study, we propose a parallel processing method for analyzing video-image radiation-response signals and suppressing radiation noise. We studied the linear-representation law of various image-information components on the radiation dose rate. Subsequently, the simulation images were used to examine the response-signal extract and radiation-noise suppression. The results indicate that the majority of response signals in the global image comprise forward superposition. The peak signal-to-noise ratio of the red channel was significantly improved when the noise signal-substitution algorithm and median filter were applied successively. Real-time radiation dose-rate measurements and clear images under irradiation can be obtained simultaneously.

The support used in a composite catalyst has an important influence on the catalytic performance of the catalyst. Amorphous metals have good electron-transfer properties and the presence of defect structures on the surface will introduce additional active sites and should be excellent catalyst supports. In this study, an Ag@AgCl composite catalyst with amorphous Cu (a-Cu) as the support is prepared by a two-step precipitation method at room temperature and a light irradiation reduction method. Compared to the Ag@AgCl and a-Cu, the catalytic rate of the Ag@AgCl/a-Cu composite catalytic rate was 2.04 times and 6.69 times faster during the reduction of 4-NP in NaBH4 aqueous solution. The high-performance catalytic efficiency and reusability of Ag@AgCl/a-Cu may be attributed to the synergistic effect between Ag@AgC and amorphous metal elements. This work may provide an effective reference for the synthesis of high activity catalysts using amorphous metals as supports.

Herein, we report the γ-ray ionizing radiation response of a commercial monolithic active-pixel sensor (MAPS) camera under strong-dose-rate irradiation with an online detection and monitoring system for strong radiation conditions. We present the first results of the distribution of three types of MAPS camera and establish a linear relationship between the average response signal and radiation dose rate in the strong-dose-rate range. There is an obvious response signal in the video frames when the camera module parameters are set to automatic, but the linear response is very poor. However, the fixed image parameters are not good at adapting to the changes of the environment and affect the quality of the video frames. A dual module online radiation detection and monitoring probe was made to carry out effective video monitoring and radiation detection at the same time. The measurement results show that the dose rate detection error is less than 5% with a dose rate in the range of 60 to 425 Gy/h, and the visible light image does not have obvious distortion, deformation, or color shift due to the interference of the radiation response event and radiation damage. Hence, the system test results show that it can be used for online detection and monitoring in a strong radiation environment.

This paper studies the response of γ-ray ionizing radiation under the irradiation of single active Pixel Sensor in the irradiation chamber and the Calibration Chamber, Designs Radiation Experiments, and analyzes and discusses the characteristic values in different statistical regions of pixels in the bright and dark environment, the linear relationship and dispersion degree between the statistical eigenvalue and the dose rate under different statistical algorithms are studied. The experimental results show that in the dark environment, the background gray values of any region in the image are in the range of 10–30, and the eigenvalue have a good linear response. Under the bright environment, the global region of the image will be confused with the neighboring region because of the different background gray values of the color region in the Byer array, which will affect the characterization of the dose rate. In low dose rate, the signal of radiation response is too small, dark current and background dark noise produce interference signal, so the signal-to-noise ratio is too low, and 300 frames of image data are needed to achieve the detection accuracy. In high dose rate, the response signal is strong, and 2 consecutive frames of image data are needed to achieve the detection accuracy. The characteristic value of threshold pixel at low dose rate is good, and the characteristic value of threshold Pixel and total gray value at high dose rate are good, which meet the requirement of wide range detection. In the radiation field experiment, we can choose the corresponding algorithm to detect the dose rate according to the field environment. This study provides theoretical basis and data support for improving gamma-ray dose rate detection technology based on MAPS image and realizing radiation field dose rate characterization. In order to use the static environment to do the radiation experiment, we can design an algorithm to cut the edge of the frame image, and use the computer image processing technology to choose the area which is advantageous to the dose rate Characterization, To realize radiation Detection in dynamic environment.