Numerical simulation of ²²²Rn profiling in an experimental chamber using CFD technique

Area of Science:

• Environmental Science
• Nuclear Physics
• Computational Fluid Dynamics

Background:

• Accurate measurement of indoor radon-222 (Rn) concentration is vital for inhalation dosimetry in residential and occupational settings.
• Understanding Rn distribution patterns is essential for calibrating detectors and ensuring accurate dose estimations.
• Computational Fluid Dynamics (CFD) offers advanced capabilities for predicting and visualizing indoor Rn concentration profiles and air mixing.

Purpose of the Study:

• To simulate the impact of forced air mixing on radon-222 concentration profiles within a controlled experimental chamber.
• To investigate the influence of parameters like time, flow rates, and fan operation on transient Rn responses and air mixing.
• To introduce and utilize a Non-uniformity Index (NUI) for quantifying Rn distribution uniformity.

Main Methods:

• Simulation of forced mixing effects on radon-222 concentration using Computational Fluid Dynamics (CFD).
• Experimental chamber (22 m³) used for controlled studies, calibration, and inter-comparison of Rn detectors.
• Analysis of transient responses, air mixing patterns, and Rn concentration profiles under varying conditions (time, flow rates, fan-on/fan-off).
• Introduction and estimation of the Non-uniformity Index (NUI) to assess distribution uniformity.

Main Results:

• Simulations revealed the transient response and air mixing patterns influenced by forced mixing parameters.
• The study quantified the effect of different parameters on the radon-222 concentration profile within the chamber.
• The Non-uniformity Index (NUI) effectively measured the uniformity of radon distribution under various simulated conditions.

Conclusions:

• Forced mixing significantly impacts radon-222 concentration profiles and distribution uniformity in enclosed spaces.
• CFD simulations provide valuable insights into turbulent conditions relevant to real indoor environments and occupational facilities.
• This research aids in the calibration and inter-comparison of radon detectors by better representing real-world conditions.