Evaluation of Safety Distances in Controlled Areas During Field Use of Mobile X-ray Flaw Detectors

Objective This study investigates the protective distance requirements for supervision and control zones in field applications of mobile X-ray flaw detection, aiming to provide a reference for defining the boundary limits during mobile deployment of the X-ray flaw detection unit’s mobile operations. Method 1. A theoretical estimation was conducted using the tenth-value layer (TVL) method, taking into account the shielding provided by protective materials and the air scattering effects configured during the factory setup of the X-ray flaw detection device. 2. The analogy method was applied by comparing the theoretically estimated distances with actual on-site measurements. 3. A comparative analysis was performed between the theoretical distances of the supervision and control areas estimated in this study and those reported in relevant literature and peer-reviewed calculations. Result The theoretical calculations value in this study show that, in the presence of a detection object, the distances between the control area and the supervision area in the main beam direction are 24, 63, 87, 121, and 138 meters. The corresponding distances between supervision areas are 47, 105, 137, 183, and 205 meters. These values are consistent with on-site measurements and are comparable to those obtained by peers when accounting for air absorption and scattering. Therefore, they can serve as reference distances for the use of mobile X-ray flaw detection. Conclusion This study provides an estimated scope of the control area within the supervision zone. When applied in field operations—together with considerations of specific working conditions, shielding environments, terrain, and other factors etc., —it can effectively reduce the time required for on-site boundary delineation and significantly lower radiation exposure for both personnel and the surrounding environment.