Modelling Underground Ventilation Networks and Radon Flow for Radiological Protection Using VUMA

In uranium mines radon (

222

Rn) is of major concern for occupational health and the concentration has to be maintained within allowable limits. It is necessary to ensure safe working conditions and occupational health in advance by predicting the expected radon concentrations throughout the underground network and to provide evidence of this in licensing procedures (SSK 1997; IAEA 2004).

This can be achieved by numerical modelling of the ventilation network as well as the contaminant transport. All flow modelling efforts require the geometrical setup of an underground network and validation. The resulting model of the network can then be used for the development of ventilation strategies with regard to contaminant transport.

This study presents the modelling of radon flow in a ventilation network of a hypothetical uranium mine using VUMA. The ventilation is modelled using the “fixed flow” option. The radon concentrations are computed using non-sitespecific but realistic radon sources. Sensitivity is studied by varying the locations and exhalation rates of radon. The results are evaluated in terms of radon concentrations and compared to allowable limits.

The results of this study using VUMA show its applicability for modelling radon flows. VUMA may be used to assess the requirements for ventilation strategies to comply with regulations for occupational radiation protection. Additional conclusions can also be drawn for effective energy management as well as safe working conditions in mines.