In the field of Probabilistic Safety Assessment, evaluation of Common Cause Failure (CCF) is one of the most important problems difficult to evaluate it systematically, and many kinds of evaluation method for CCF have been developed.
The MGL (Multiple Greek Letter) method developed by K. N. Fleming is one of CCF evaluation methods. It was derived for the higher order (more than the third order) redundant systems as an extension of the β-factor method which is essentially applied only to the second order redundant systems.
Values of the parameters defined in the MGL method change with the order of redundancy due to its definition of the parameters, as an example, simultaneous failure probability of two units of the second order redundant system and that of the third order redundant system are different from each other even if failure probability of each unit has a same value.
This paper tried to modify the MGL method in order to have no change of its parameters through out all the order of redundancy.
As a result of this modification, the parameter change with the order of redundancy is eliminated, and acceptable ranges of values of new parameters are determined, while relations between new modified parameters and usual MGL parameters are obtained.
Furthermore, results of some application to practical redundant systems are shown.
抄録全体を表示