Model development, standard scenarios

The use of uncertainty analysis and probabilistic methods requires systematic and detailed formulation of the assessment problem. To facilitate this, a) risk assessors and risk managers should be given training in problem formulation, b) tools to assist appropriate problem formulation should be developed, and c) efforts should be made to develop generic problem formulations (including assessment scenarios, conceptual models, and standard datasets), which can be used as a starting point for assessments of particular pesticides. 

A starting point could be to develop models for focal species and agree on standard scenarios. We believe that it is best to start simple and show the benefits of modeling in risk assessments. In this way the methods and outputs can be made transparent, and that will build confidence in ecological modeling as a risk assessment tool. 

The tutor uses information from the student assessment and from the expert model to generate instructional sequences. At this point, if a student misses a declarative knowledge question, s/ he is transported to the hypertext node (card) that contains that information. If the student misses a structural knowledge question, then the expert model expert system is activated, generating an optimal structural path for the learner. This path is then illustrated for the learner. If the learner misses a procedural knowledge question, practice scenarios are provided with standard practice and feedback. The assumptions and sophistication of this part of the tutor needs development. 

ABSTRACT In order to incorporate domino effect scenarios, deriving from the projection of fragment (so-called missile), within the standard QRA (Quantitative Risk Analysis), a probabilistic model for the estimation of the impact probabiUty of such fragment was developed by applying a Monte-Carlo method to the analytical solution of the set of equations describing the motion of the missile. The objective of this work is to further extend this probabilistic approach, which was previously developed for cylindrical vessels, to make it apphcable also to spherical tanks. A case study is presented, it is the accident occurred in the refinery of Feyzin (France) the influence of the size and shape of the fragments on the impact probability is assessed. 

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