Objective
To promote and improve methods for probabilistic safety assessment (PSA) of systems, taking into account acquisition of operational data, development of data analysis methods and their application and human factor aspects.
Progress to end 1990
This activity has covered in 1990 two main projects: the Component Event Data Bank - CEDB and the System Response Analyser - SRA, and a more theoretical development on data analysis methods with applications to the CEDB.
- Component Event Data Bank: the number of components and related failures has increased significantly (15.000 and 8.000 resp.), mainly because of the supplying by UNESA (Spain) of data from 10 NPPs in operation. Computer programs to insure the quality of the data have been developed together with a semiautomatic transcoding system to transfer already coded data into CEDB.
- Data analysis: methods and procedures have been developed for an effective selection of samples and for the application of logistic regression to model the probability of first failure. The benchmark exercise on analysis methods has been completed.
In the field of expert judgement data and fusion of data from various sources it is worth mentioning the acquisition of the EXCALIBR software from the Delft University and the realization of programs based either on possibility theory and on Bayesian procedures.
- System Response Analyser: the first meeting of the SRA users-group has been held and the importance of the SRA project for designing procedures and control requirements of the plant has been recognized. The possibility of proposing the SRA project development in one of the Reinforced Concerted Actions of the Commission's nuclear safety research program is under scrutiny. As far as 1990 results, the issue of a new version of the DYLAM methodology (DYLAM-III) has to be mentioned; in this version, which constitutes the driver of the SRA, a new methodology for the evaluation of the dynamic probability of sequences has been implemented.
In the human modelling area a cognitive simulation model (COSIMO) has been implemented exploiting a Blackboard architecture
A prospective study of the use of PSA methods for accident management was started. Detailed description of work foreseen in 1991 (expected results)
- CEDB will continue to be operated. Liaison with other organizations (WANO, Commission DGs etc.) will be sought to assure the future management of the bank.
- Data analysis tools development will concentrate on multivariate techniques for producing a CEDB Handbook of reliability parameters.
- Expert judgement and multi-source data fusion programs will be finalized to the preparation of a benchmark on expert judgement applied to a PRA level 2 (containment failure).
- The SRA development will result in a first software package dedicated to the Auxiliary Feedwater Systems of nuclear power plants immediately applicable to study real cases of man-machine systems. This package may contribute to the design of new interfaces and new safety procedures of future plants.
- The prospective study, performed in collaboration with ABB and FRAMATOME, on the use of PSA for safety management will result into a functional specification of a 2nd generation "Living PSA" tool.
Short description of evolution of work in 1992
The CEDB data analysis effort will be continued, extension of the techniques to new areas such as critical computer systems, quality control of production processes, working environment monitoring etc. will be attempted.The SRA development will be concentrated on the formulation of a more general architecture based on simulation languages in order to extend the application of SRA to many systems with minor efforts from the user.
Advanced methods for NPP safety monitoring and management based on the "living PSA" concept and including plant aging considerations will be developed.
Topic(s)
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21020 Ispra
Italy