Loss-of-containment events on offshore installations can lead to complex escalation effects, especially in congested modules, where the close proximity of processing equipment and control systems creates the potential for very many different escalation paths. Conventional risk analysis tools are not well suited to deriving and evaluating the large number of possibilities, relying on the risk analyst to devise and quantify a ＇representative＇ set of scenarios. The danger is that the ＇representative＇ scenarios lack realism, may be insufficiently detailed to support upgrade decisions, and tend towards ＇generic＇ risk analysis. A novel computer simulation technique has therefore been developed which starts from a list of initiating loss-of-containment events and utilizes physical rule sets and consequence models to generate consistent and detailed accident scenarios from a basic platform description, comprising a collection of equipment items, structural elements and protective systems. The program has proved stable on application to a variety of offshore installations, including simple gas platforms, a typical deep sea oil and gas platform, and a semi-submersible production vessel. It eliminates the manual drafting and analysis of event trees, which is very laborious even when aided by interactive computer tools; and, because the risk model comprises factual information, rather than abstract concepts, it is much more accessible and amenable to scrutiny by discipline engineers, allowing operators to derive and maintain a genuinely ＇living＇ quantitative risk assessment.