Parameter uncertainty analysis of the committed equivalent dose coefficients from inhalation of radon progeny in underground uranium mines

Abstract

This study evaluates the uncertainties in committed equivalent dose coefficients from inhalation of radon progeny in underground uranium mines. The work focuses on two exposure scenarios: wet drilling with good ventilation (Job 1) and dry drilling with poor ventilation (Job 4). The use of Monte Carlo simulations informed by the International Commission on Radiological Protection (ICRP) latest biokinetic models and parameter probability distributions obtained from published literature, revealed that Job 4 conditions yield higher lung dose coefficients than Job 1, despite both scenarios exhibiting similar uncertainty levels. The committed equivalent lung dose coefficients followed lognormal distributions, with geometric means of 61.87 mSv/(mJh/m³) and geometric standard deviation of 1.56 for Job 4 and 47.05 mSv/(mJh/m³) and geometric standard deviation of 1.58 for Job 1. The alveolar-interstitial region showed the greatest uncertainty, while the bronchial secretory cells received the highest doses. Among systemic organs, the kidneys received the largest dose. Statistical tests confirmed significant differences between the two job types. Sensitivity analysis identified tidal volume as main contributor to committed equivalent lung dose coefficient uncertainty. These findings support revising model parameters and improving breathing parameter measurements to enhance dose accuracy. The study emphasizes the necessity for enhanced ventilation, stricter air quality standards, and advanced personal protective equipment to mitigate health risks in radon-prone mining environments.