Improving system reliability using conditional reliability importance

This paper presents a way to improve the system reliability of coherent systems consisting of components with independently distributed lives. Performing better maintenance, using better quality components, replacing older components by newer ones, or reducing operational load on the critical components are some of the ways in which the system reliability can be improved. The issue arises when we wish to select an optimal arrangement of components, keeping in view the cost effectiveness of the method adopted. Here an attempt has been made to improve system reliability by reallocating the components considering their reliability importance. To achieve this, the knowledge of the order of the component reliabilities is sufficient. Their individual values are not required for deciding if the positions of the components need to be changed. The method is illustrated with examples of different systems. A numerical example is given to explain how the procedure can be used to arrive at an optimal arrangement of components. An application of the result derived in this paper has been discussed in the context of the main power supply system of a nuclear power plant.