The Common Mode Failure Study Discipline

A Common Mode Failure (CMF) study is described which supports the design basis for the Reactor Protection System on a General Electric Boiling Water Reactor. Ground rules are formulated which restrict the study to functional CMFs applied one at a time to a reactor plant subjected to initiating transients and accidents. Each outcome is traced to a stable condition and the results examined to determine that they are acceptable. CMF studies seem to parallel the development of Reliability studies and the results appear to be complimentary.