CFD modelling of thoron and thoron progeny in the indoor environment

Abstract

Thoron (220Rn) exhalation from building materials has become increasingly recognised as a potential source for radiation exposure in residences. However, contrary to radon (222Rn), limited information on thoron exposure is available. The purpose of this study is to estimate the concentration of thoron and its progeny products in a typical Dutch living room using computational fluid dynamics. The predicted thoron concentration is ∼9 Bq m(-3) using a source term of 14 Bq s(-1) for the thoron exhalation from building materials. The concentration varies from 15 Bq m(-3) near the building materials to 2.7 Bq m(-3) in the centre of the living room. The mean effective dose from thoron progeny is calculated as 0.09 mSv y(-1), with a total effective dose from radon and thoron progeny of 0.38 mSv y(-1).

Impact from indoor air mixing on the thoron progeny concentration and attachment fraction

“…In these computations a thoron source of 4.35 Bq s À1 is applied to the room surfaces. The exhalation rate is theoretically derived and typical for the Dutch housing stock (De With and De Jong, 2011).…”

“…In recent years also advanced Computational Fluid Dynamics (CFD) models have been developed to model the dispersion of thoron (Chauhan et al, 2015) and its progeny as well as the attachment and deposition of the progeny nuclides (De With and De Jong, 2011).…”

Distribution of indoor thoron in dwellings under normal and turbulent flow conditions using CFD simulation technique

“…Fi nite vol ume discretisation tech nique was im plemented in code to gen er ate the grid points. The air flow was as sumed to be in com press ible [15]. Fine mesh was used near the doors and the open ings, which gave the pre cise re sults with less com pu ta tional time.…”

“…Thoron dis tri bu tion pat tern in in door en vi ronment is non-ho mog e nous un der the closed room condi tion with poor ven ti la tion [15,16]. Af ter re leas ing from room sur faces thoron gets dis trib uted in in door en vi ron ment along with spon ta ne ous de cay.…”

Measurements and CFD modeling of indoor thoron distribution

“…It was shown that difference in source term of room surfaces led to in-homogeneity of radon distribution but on an average, simulation results were found to be close to experimental measurements. CFD model based results of indoor thoron distribution have not been validated experimentally (Urosevic et al, 2008;With et al, 2011). The objective of this study is to measure indoor thoron distribution and compare the results with CFD model predictions for a typical model room.…”