Polynomial Interpolation Model for Gamma Radiation Dose-Rate Screening at Radiation-Hazardous Industrial Sites: A 2021 Case Study of the Base-S Tailings Facility

Radiation monitoring at contaminated industrial sites is often restricted by safety, access, and operational constraints. Under such conditions, a modelling approach that can use a limited number of field measurements is useful for preliminary screening, route planning, and prioritization of verification surveys. This study presents a sparse spatiotemporal polynomial interpolation model for estimating the gamma radiation equivalent dose rate (EDR) along the perimeter of the Base-S radiation-hazardous industrial site. The model represents EDR as a function of spatial coordinates and time, and uses a reduced measurement structure consisting of four seasonal temporal nodes and five representative spatial nodes. The reduced structure is intended to support conservative preliminary assessment under the ALARA principle, not to replace field measurements. A 2021 case study is presented for 61 numbered perimeter points. The article presents one of the universal mathematical models developed by the authors to determine the impact of gamma radiation on the personnel of tailings facilities and industrial sites through the calculation of the equivalent dose rate during personnel residence stays, depending on time. The proposed polynomial interpolation model for rapid radiation dose assessment at radiation-hazardous industrial sites estimates equivalent dose-rate values for a specific planning case. The model represents the EDR field as a spatiotemporal polynomial f(x, y, t), where x and y are planar coordinates, and t is the day of the year. A conservative reduced scheme uses four seasonal maximum values and five representative spatial points to decrease the number of required field measurements and personnel residence time. For the 2021 case study, the model-estimated EDR at 61 numbered perimeter points ranged from 0.118 to 0.415 µSv/hour, with a mean of 0.242 µSv/hour. This model provides initial data for building a 2D model and, if necessary, a 3D model of radiation contamination within the research-object territory. The resulting 2D and 3D maps are interpreted as model-estimated visualization products. The proposed method, the model form of which is described as a cubic polynomial in t and a quadratic in x,y, allows for effective interpolation of complex multidimensional dependencies of observed data.