Evaluation of hazards from industrial activity near nuclear power plants. Study of typical accidents

The design and dimensioning of nuclear power plant structures necessitate the evaluation of risks due to industrial activity. Among these risks, those due to the storage or transport of dangerous products merit special attention. They result, inter alia, in the explosion of flammable gas clouds. Such clouds can drift before igniting and, once alight, the resulting pressure wave can cause serious damage, even at a distance. A methodology both deterministic and probabilistic enabling this risk to be quantified has therefore been developed. It is based in part on an analysis of the statistics of actual accidents that have occurred. After briefly recalling the probabilistic model, the typical accidents selected are described and for three usual cases (storage under pressure, rail tank cars and road units) the main characteristics of the rupture are explicited. The deterministic models that have been worked out to calculate the consequences of such an accident: flow rate at the bursting point, evaporation, drift and atmospheric dispersion of the cloud formed, explosion of this cloud, are then described. At the present time the overpressure wave is quantified against a TNT equivalent of the explosive mixture. Some data are given as examples for three commonly employed hydrocarbons (butane, propane, propylene)