Uranium hexafluoride release assessment

There are many available vapor cloud dispersion models that can be applied on UF6 release assessments, with a great variation in capabilities and accuracies. Sometimes it is wise to carry out a gross screening analysis prior to embarking on a modeling exercise, since it may be that the predicted concentrations are orders of magnitude below some limits; this screening analysis can also be used to check the magnitudes of the results of subsequent detailed model applications. This paper is intended to present a simple method which can be used to assess the possible consequences of UF6 releases and determine the need for preventive and mitigating actions. The proposed model for atmospheric dispersion is based on the Gaussian plume, which model has been modified to take account two specific effects: plume rise and/or building wake. The proposed model is validated using data of an accident that occurred in 1978 at Ohio gaseous diffusion plant, where within one our about 9500 kg of UF6 escaped outdoors. The results are presented in terms of concentrations of HF and uranium intake. (author)