APPLICATIONS OF SOME RISK ASSESSMENT TECHNIQUES - FORMAL EXPERT JUDGMENT AND ACCIDENT SEQUENCE PRECURSORS

Risk assessments are carried out as a support for decision making on m ajor hazards activities. The risk assessments are explanatory in natur e and are not aiming at predictions of accidents which might occur. Tn various areas a lot of experience has been gained with risk assessmen ts, for which well known techniques (like FMEA, fault trees and so for th) are applied. In quantifying risks, the prior position is often a s carce amount of necessary data on component failures or specific pheno mena. The decision to pick the 'right' numbers is therefore Limited. T here is felt a need to collect data with other techniques as well. The paper describes two such techniques: (i) a formal expert judgement te chnique to establish quantitative subjective expert assessments on des ign and model parameters, and (ii) a system failure analysis technique (Accident Sequence Precursor Methodology) which uses operational evid ence of system failures to derive the system failure probability of th e system as a whole. For both techniques an example case is presented for illustration. (C) 1997 Elsevier Science Ltd.