Model for Reconstruction of γ-Background during Liquid Atmospheric Precipitation

Valentina Yakovleva,Aleksey Kobzev,Aleksey Zelinskiy,Roman Parovik,Grigorii Yakovlev

doi:10.3390/math9141636

Abstract

With regard to reconstructing the gamma background dose rate, existing models are either empirical with limited applicability or have many unknown input parameters, which complicates their application in practice. Due to this, there is a need to search for a new approach and build a convenient, easily applicable and universal model. The paper proposes a mathematical model for reconstructing the temporal evolution of the ambient equivalent γ-radiation dose rate during rain episodes, depending on the density of radon flux from the soil surface, as well as the duration and intensity of rain. The efficiency of the model is confirmed by the high coefficient of determination (R2 = 0.81–0.99) between the measured and reconstructed ambient equivalent dose rate during periods of rain, the simulation of which was performed using Wolfram Mathematica. An algorithm was developed for restoring the dynamics of the ambient equivalent γ-radiation dose rate during rainfall. Based on the results obtained, assumptions were made where the washout of radionuclides originates. The influence of the radionuclides ratio on the increase in the total γ-radiation dose rate was investigated.

Highlights

Published: 11 July 2021Radon and its decay products are naturally occurring radionuclides found in the atmosphere around the globe
Whilst the equations for the balance of activities in the air have been known for a long time [10], our new approach is that we directly model the dynamics of radionuclides in an air column that starts from the Earth’s surface with an area of 1 m2 and extends to the lower edge of the clouds
To assess the effectiveness of the model, it is necessary to compare the data series obtained from the gamma radiation detector and the dose rate series reconstructed from the precipitation intensity

Summary

Introduction

Radon and its decay products are naturally occurring radionuclides found in the atmosphere around the globe. The isotope of radon 222 Rn is formed as a result of the radioactive decay of 226 Ra (radium) in the 238 U (uranium) chain contained in the Earth’s crust. The γ-emitting radon decay products 214 Pb (plumbum) and 214 Bi (bismuth) have a short half-life of 26.8 and 19.9 min, respectively, and can accumulate in the atmosphere in sufficiently high activities. They can join aerosols existing in the atmosphere. When liquid atmospheric precipitation falls, raindrops are deposited on the Earth’s surface—both non-radioactive aerosols 214 Pb and 214 Bi

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