Development of a theoretical framework for the evaluation of risk connected to accidental oxygen releases

•An original approach to evaluating hazards from oxygen releases and related accident scenarios.•Build-up of oxygen and hydrocarbons in semi-confined geometry.•Pipeline risk assessment.•Safety distances estimation.•Short-cut dispersion modelling for continuous and nearly instantaneous releases. A short-cut methodology for a fast estimation of hazards from oxygen releases and the evaluation of safety distances is presented. Starting from a historical survey on accidents involving oxygen releases and consequent scenarios, the approach includes analytical models for the quantification of incremental hazards due to oxygen releases, in non-obstructed areas, both for continuous and nearly instantaneous scenarios, adopting a simple Gaussian dispersion model. An example of the application of the model in a real case-study and relevant quantitative results are presented.