A Computational Fluid Dynamics code for aerosol and decay-product studies in indoor environments

Application of CFD modeling for indoor radon and thoron dispersion study: A review

This paper provides an in-depth discussion of the CFD implications to the design/study of interior environments and an overview of the most widely used CFD model for indoor radon and thoron dispersion study. For the design and analysis of indoor environments, CFD is a powerful tool that enables simulation and measurement-based validation. Simulating an indoor environment involves deliberate thought and skilful management of complicated boundary conditions. User and CFD programs can develop results through gradual effort that can be relied upon and applied to the design and study of indoor environments. Radon and thoron are natural radioactive gases and play a crucial role in accurately assessing the radioactive hazard within an indoor environment. This review comprise the work related to measurement and CFD modeling on these radioactive pollutant for indoors.Highlighting the current state of environmental radioactive pollutants and potentially identified areas that require further attention or research regarding investigating factors affecting indoor radioactive pollutants.

A CFD-based approach to study the deposition and distribution behaviour of 212Pb in a calibration chamber

Among the several aspects of decay products behavior, deposition is of special significance because of its prominent role in the activity removal from the environment, which eventually results in the occurrence of decay product disequilibrium with the parent gas. This point is particularly important in case of thoron dosimetry where thoron progeny ²¹²Pb accounts for the most of the radiological dose. The deposition depends on the size distribution of decay products and the structure of air turbulence at the air-surface interface. In the present work, the effect of varying air-flow (fan speed) and aerosol count median diameter (CMD) was studied on the deposition and distribution profile of ²¹²Pb using computational fluid dynamics (CFD). The simulations have been carried out in a cubical calibration chamber of volume 8 m³, facilitated at RP&AD, BARC. Simulated results showed that the increase of total depositional loss rate of attached fraction of ²¹²Pb due to increase of the fan speed was significant for CMD up to 400 nm, beyond which this effect started becoming less prominent with increasing diameter. Besides, a minimum of the total depositional loss rate curve was seen to be shifted to the higher CMD with increase of the fan speed. CFD results were found to be in good agreement with experimental observations obtained in the controlled conditions with thoron source.

A CFD-based approach to optimize operating parameters of a flow-through scintillation cell for measurement of 220Rn in indoor environments

The measurements and monitoring of ²²²Rn/²²⁰Rn have been of emerging interest in occupational environments particularly in radium/thorium handling facilities and environments with monazite deposits for the inhalation dosimetry. The performance of a flow-through Lucas scintillation cell (LSC) for long run ²²⁰Rn measurements, depends upon the exact distribution pattern of ²²⁰Rn and its decay products in the LSC which can vary with the design of inlet path and flow rates. In this work, the CFD technique has been used to study the concentration profiles of ²²⁰Rn and its decay products in LSC for varying flow rates and inlet needle lengths. The variation of alpha production efficiency (η_α) is computed and analyzed for each case; aiming to select the best operating range of parameters for the optimum performance of LSC for ²²⁰Rn measurements. It is seen that LSC can be operated in the flow rate ranging from 0.6 to 1 lpm with inlet needle length varying from 22.5 to 45 mm for improved sensitivity.