Design of the sparrow search algorithm (SSA) for airborne radioactive hotspot detection.

In the context of using aircraft as a pivotal tool for detecting radioactive hotspots, the acquisition of radioactivity data was conducted through a CeBr3 scintillation crystal detector mounted on a helicopter. However, challenges arose, including managing extensive data volumes, computationally demanding tasks, and susceptibility to local optima issues. To address these challenges and leverage the benefits of the Sparrow Search Algorithm (SSA) in global optimization and convergence speed, an improved SSA was devised. This improved version integrated SSA principles with the intricacies of searching for radioactive hotspots. The algorithm employed a matrix segmentation method to process data matrices derived from measured data, aiming to enhance efficiency and accuracy. An empirical analysis was conducted, performing 100 iterations on an experimental matrix to scrutinize the impact of matrix segmentation. Computation times and results were compared across different segmentation levels, confirming the favorable algorithmic outcomes of the method. The practical viability and convergence stability of the algorithm were further assessed using genuine measured data, with segmented matrices generated for evaluation. Remarkably, a comparison between computational outcomes and manually identified data reaffirmed the algorithm's reliability in effectively detecting radioactive hotspots.

A gamma ray sourceless efficiency calibration method based on the Boolean operation of the ray deposition process.

The general sourceless efficiency calibration has two major methods, Monte Carlo simulation and numerical calculation. Monte Carlo simulation as an important method to address the efficiency calibration in complex measurement systems, despite it being highly accurate, but inefficient and time-consuming. And although the numerical calculation is computationally efficient, its accuracy is highly influenced by the multiple Compton scattering of rays in sensitive body, and it is difficult to deal with complex measurement systems. To solve the above problems, this paper proposes a discrete numerical calculation combined with the graphical Boolean operations method for sourceless efficiency calibration. The method starts with a Monte Carlo simulation to obtain the rays deposition process in an infinite sensitive body and record deposition locations as a matrix; then, for different measurement systems, discrete numerical calculations are used to rapidly obtain the transmission process of rays to the sensitive body of the detector; finally, the two are combined to obtain the detection efficiency of the rays by using graphical Boolean operations. For the given two test models, the error between the measured and calculated results of 241Am, 137Cs, 60Co at 60 positions is within -3.61∼9.71%, and the error between the measured and calculated results of the soil source is within -1.27 to 4.26%, indicating that the method has high reliability in sourceless efficiency calibration. And in comparison with Monte Carlo simulations, it is found that the method has a good agreement with Monte Carlo simulation in efficiency calibration and the computational speed has been greatly improved.

INVESTIGATION OF ENVIRONMENTAL RADIOACTIVITY AT A DECOMMISSIONED URANIUM MINE IN SOUTHERN CHINA.

An environmental radioactivity survey was performed on a uranium mine that has been decommissioned for >10 y. According to the characteristics of this uranium mine, the relevant parameters, such as the surface-absorbed dose rate in air, the radon and radon progeny concentrations in the air, the radon exhalation rate from the soil surface and the concentrations of natural radionuclides in soil and surface water, were measured. The results show that the maximum annual effective doses of residents and employees in the uranium mine caused by radon and radon progenies inhalation were 1.48 and 1.74 mSv, respectively, and the maximum annual effective doses of residents and employees caused by gamma-ray external radiation were 1.16 and 1.32 mSv, respectively.

INVESTIGATION AND ANALYSIS OF ENVIRONMENTAL RADIOACTIVITY LEVELS AT TYPICAL URANIUM MINES IN THE SOUTH OF CHINA.

The environmental radioactivity levels of two typical uranium mines in the south of China were investigated and analysed. According to the characteristics of uranium mines, the relevant parameters, including the surface gamma ray dose rate, concentration of radon in the air and concentration of radionuclides in the soil and surface water, of two uranium mines were evaluated and analysed. The results show that residents in the mining area were exposed to average maximum annual effective doses of 1.69 and 1.58 mSv due to the inhalation of radon and its daughters, while the employees received 2.59 and 1.87 mSv, respectively. Residents in the mining area were exposed to average maximum annual effective doses of 0.77 and 0.69 mSv due to gamma ray, while the employees received 1.64 and 1.33 mSv, respectively.

A hybrid method on sourceless sensitivity calculation for airborne gamma-ray spectrometer.

The sensitivity calculation of airborne gamma-ray spectrometer (AGS) is usually performed by on-ground or in-flight calibration. However, both methods are cost-ineffective or not permissive, especially for artificial radioisotopes with short half-lives. Alternative to these methods is the Monte Carlo simulation, which has been widely applied over the last few decades. The greatest challenge to the practicability of the Monte Carlo simulation in the AGS calibration is its low computational efficiency for ensuring an acceptable reliability. This article proposes a hybrid numerical method for the sourceless AGS calibration by combining the deterministic point-kernel approach and the Monte Carlo simulation. This method is not only more efficient than the source-based calibration by an empirical method, but also independent of the source availability for on-ground or in-flight calibration. For a given soil test model, AGS sensitivities calculated by this hybrid method agree well with those obtained from the empirical method for the in-flight calibration.