Contamination Measurements from Simultaneous Activated Potassium Bromide Radiological Dispersal Devices with a Collimated Vehicular Sensor

Abstract

Surface contamination was quantified over a distributed source of activated potassium bromide from three detonations of Radiological Dispersal Devices (RDDs) at the Idaho National Laboratory Radiological Response Training Range, with a maximum sampled area of 19,900 m2, to provide a baseline comparison with other rapid, remote mapping methods. Measurements were obtained with a cerium bromide sensor collimated to a field of view of 3.14 m2, using lead shielding, and towed behind a ground vehicle. Sensor response correction factors for activated potassium bromide were calculated through simulation with SWORD to obtain activity per meter-squared. Continuous maps were produced by interpolating coverage from lawnmower raster scans. Radiological data was overlaid with aerial imagery from an automated unmanned aerial vehicle flight to provide contextual geological information relative to contamination levels. The contamination distribution measurements will be compared to unmanned aerial vehicle methods in future work.

Design and deployment of radiological point-source arrays for the emulation of continuous distributed sources

“…12) since Compton scattering always reduces the photon energy. To compensate for this in-scatter without running computationally intensive scattering simulations, 6 we derive an approximate buildup correction from the global 511 keV peak (i.e., summed over the entire run) from the NG-LAMP run in Fig. 12.…”

“…Third, producing truly continuous distributions of radioactive material with known ground truth patterns is also difficult-the deposition of powdered, aerosolized, or dissolved materials may deviate from the intended pattern due to factors such as changing winds or uneven mixing due to the mechanical variability of the depositor in inclement weather [1]. Post-deposition ground truth activity assays are possible using collimated high-purity germanium (HPGe) [5] or cerium bromide (CeBr 3 ) [6] detectors, but these measurements require very close proximity to the source (increasing dose and often disturbing contaminated soil) and are limited to small ( 1 m 2 ) areas in a single measurement, and thus are difficult to use for rapidly mapping large distributed sources spanning hundreds or thousands of square meters. While remotely-or autonomously-controlled ground robots could be used to carry the detectors used for the ground truth measurements and this would mitigate dose concerns, their use would create additional complications such as ensuring the robots did not disturb the source distributions or become radiologically contaminated themselves.…”

Aerial and Collimated Sensor Radiological Mapping Following Dispersal of Activated Potassium Bromide

“…Results from simulations of the CeBr sensor in SoftWare for Optimization of Radiation Detectors (SWORD) were coupled with intensity data to generate detailed maps of the source distribution on the ground (Gwon et al 2007). This process is described in greater detail in prior work (Simerl et al 2021).…”

“…Precise mapping of an activity distribution can be achieved with a collimated, ground-based gamma-ray spectrometer (Simerl et al 2021). A narrow FOV suppresses response from radiation emitted at shallow angles to the surface and results in better characterization of the source directly below the sensor.…”