Recent changes to French legislation, concerning the prevention of technological risk, require industrial sites to calculate an effect distance for different accident scenarios, based on a detailed probabilistic risk assessment.
The effect distances shall be used to establish strict land use planning guidelines in order to mitigate the effects of residual risks after all reasonable preventive measures have been taken. These land use guidelines are elaborated at a local level, and consist of consultation with all stakeholders. The guidelines include restrictions on future construction in medium-risk zones surrounding sites, and the possibility of forced expropriation of home owners in areas with a high level of risk.
This debate on land use planning around industrial sites is politically sensitive. It is important that the safety perimeters resulting from risk assessment studies are based on the best scientific knowledge available, and that the level of uncertainty is minimised.
Reducing uncertainty in dispersion modelling
A significant contribution to effect distance calculations comes from the modelling of atmospheric dispersion, particularly of the accidental release of toxic products. One of the most widely used tools for dispersion modelling in France is Phast. This software application is quite flexible, allowing the user to alter values for a wide range of model parameters. Users of the software have found that simulation results may depend quite strongly on the values chosen for some of these parameters. While this flexibility is useful, it can lead different users to calculate effect distances that vary considerably even when studying the same scenario.
The Institute for an Industrial Safety Culture (ICSI) shall sponsor a research project aiming at improving knowledge about the modelling of accident scenarios and the parametric sensitivity of dispersion modelling tools (and in particular Phast). A planned deliverable of this work is a report providing recommendations on source/hazard characterisation, and on criteria for selecting parameter values in different release scenarios. Another more general aspect of the work will investigate the impact of uncertainty in dispersion modelling on public decision making concerning land use planning.
This research is primarily financed by a number of ICSI’s industrial partners, including Rhodia, TOTAL, Sanofi-Aventis, Air Liquide and Arkema. Companies that are specialised in risk assessment studies, including Technip, URS and IRSN, shall also participate in the project, which DNV Software is associated with. The research will be a part of a PhD thesis carried out by the Laboratoire de Génie Chimique de Toulouse.
Authors:
Nadine Gabas (Laboratoire de Génie Chimique
de Toulouse)
Eric Marsden (ICSI)
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| Institute for an Industrial Safety Culture | Laboratoire de Génie Chimique de Toulouse |
The Toulouse-based Institute for an Industrial Safety Culture (ICSI) works to improve safety in industry and to promote debate between high-risk companies and civil society. ICSI’s members include large industrial groups, academic and research organisations, trade unions, and local and regional government bodies, primarily in France. The Institute has three types of activity:
| Laboratoire de Génie Chimique was created in 1965 and became part of the Centre National de La Recherche Scientifique (CNRS) in 1973. It is also linked to two Research is carried out in diverse scientific areas, including reaction engineering, mixing and separation processes, interface and particle interactions, electrochemistry, materials, process systems engineering and industrial engineering. In these areas, more than 200 researchers, engineers and technicians search for solutions and improvements in order to satisfy the needs of the process industries. |