Radioactive Source Localisation via Projective Linear Reconstruction

Abstract

Radiation mapping, through the detection of ionising gamma-ray emissions, is an important technique used across the nuclear industry to characterise environments over a range of length scales. In complex scenarios, the precise localisation and activity of radiological sources becomes difficult to determine due to the inability to directly image gamma photon emissions. This is a result of the potentially unknown number of sources combined with uncertainties associated with the source-detector separation—causing an apparent ‘blurring’ of the as-detected radiation field relative to the true distribution. Accurate delimitation of distinct sources is important for decommissioning, waste processing, and homeland security. Therefore, methods for estimating the precise, ‘true’ solution from radiation mapping measurements are required. Herein is presented a computational method of enhanced radiological source localisation from scanning survey measurements conducted with a robotic arm. The procedure uses an experimentally derived Detector Response Function (DRF) to perform a randomised-Kaczmarz deconvolution from robotically acquired radiation field measurements. The performance of the process is assessed on radiation maps obtained from a series of emulated waste processing scenarios. The results demonstrate a Projective Linear Reconstruction (PLR) algorithm can successfully locate a series of point sources to within 2 cm of the true locations, corresponding to resolution enhancements of between 5× and 10×.

CARMA II: A ground vehicle for autonomous surveying of alpha, beta and gamma radiation

“…Mobile robots in a variety of forms and levels of autonomy are commonly used within nuclear facilities. These robots have been developed and deployed for a variety of purposes, such as decommissioning (Marturi et al, 2017;Marques et al, 2021;Monk et al, 2021;West et al, 2021) and monitoring (Li et al, 2018;Groves et al, 2019;Anderson et al, 2020;Connor et al, 2020;White et al, 2020White et al, , 2021Abd Rahman et al, 2022a). A number of these systems have been trialled and evaluated in active nuclear facilities such as the Fukushima Daiichi nuclear power plant in Japan (Nagatani et al, 2013;Nancekievill et al, 2018) and the Dounreay site in the United Kingdom (Bird et al, 2022;Nancekievill et al, 2023).…”

Radioactive source localization employing resistive electrode array (REA) detector

“…Other potential uses of the REA localization capability is in Radioisotope Identification (RIID) in health safety and national security [6]. Various detectors have been used in radioactive source localization [7][8][9][10][11][12][13][14]: radiosensitive films, at panel detectors (Electronic Portal Imaging Device (EPID)), gamma camera, photon counting detectors, scintillators, and others. Typically the detector is at a fixed position and radioactive sources are either static or moving.…”

Mathematical aspects of remote assessment of the radiation state of contaminated areas

“…To organize the effective control and correct handling of radioactive materials and to provide the radiation safety, small flying machines or so-called unmanned aerial vehicles (UAVs) began to apply widely. The advantages [5][6][7][8][9][10][11] of this approach are well known. Among them are:…”

“…When radiation fields are considered, special attention is paid to the development of procedures for identifying the array of detector's readings [8,9,14,15]. The choice and details of the implementation of such procedures depend on the problem's specifics, but, as a rule, they are based on the statistical nature of the signals being recorded.…”