Sensitivity Analysis of the Influence of Building Geometric Structure on Indoor Gamma Dose Rate

To investigate the influence characteristics of building materials on the indoor radiation environment in practical applications and to quantitatively evaluate the regulatory effects of architectural design parameters on the indoor γ dose rate, a three-dimensional calculation model for the absorbed dose rate in air in a standard room was established using the Monte Carlo method, and the indoor dose field distribution was analyzed. The results show that the absorbed dose rate in air in a standard enclosed room exhibits a gradient distribution characterized by lower values at the center and higher values at the edges, with dose peaks appearing in corners and edge regions due to the superposition of multiple near-field sources. Sensitivity studies on building geometric parameters indicate that, when the room height is fixed, the central dose rate changes non-monotonically with the room volume: as the room volume expands from 2.8 m3 to approximately 25.2 m3, the central dose rate decreases, whereas it gradually increases compared to the standard room when further expanded to 280 m3. With a fixed floor area, the central dose rate shows a monotonically decreasing trend with increasing room height. After introducing realistic asymmetric openings such as doors and windows, the dose field presents significant asymmetric distribution characteristics. The influences of window size and position on the dose were analyzed, and a typical residential layout with an off-center door and a centered window was established. It is found that low-dose channels are formed in the extension areas of the openings, causing the indoor extreme dose points to deviate from the geometric center.