A new method for evaluation of the qualitative importance measures

The importance measures utilized in Probabilistic Safety Assessment (PSA) are divided into quantitative and qualitative. The qualitative importance measures are derived from the qualitative, logic structure of the PSA that includes the fault tree and event tree models. The exact logic expression of the selected risk measure is required input for assessment of the qualitative importance measures. A new method for assessment of the qualitative importance of the events in the fault tree is developed and presented in this paper. The qualitative importance of the events is assessed with new qualitative importance measure obtained from the Birnbaum importance measure and application of the min cut upper bound approximation. The minimal cut sets of the analyzed system, as standard qualitative result, are required input for the assessment of the new measure. The developed method is applied on the fault tree representing safety system in the nuclear power plant. The ranking of the events based on new qualitative importance measure is compared to the ranking based on structural measure of importance. The structural measure of importance of the events is assessed with application of the algorithm that utilizes binary decision diagram. Obtained results include ranking of the events based on the new qualitative importance measure and comparison to the ranking obtained by structural importance measure. Utilization of the new qualitative importance measure, together with quantitative importance measures, for classification of the systems, structures and components in nuclear power plants is discussed.

VOLKANOVSKI Andrija;  MATUZAS Vaidas; 

2017-07-31

CRC Press

JRC104774

978-1-138-62937-0,   

https://www.crcpress.com/ESREL-2017-Portoroz-Slovenia-18-22-June-2017/Cepin-Bris/p/book/9781138629370,    https://publications.jrc.ec.europa.eu/repository/handle/JRC104774,