Risk-based configuration control system: Analysis and approaches

This paper presents an evaluation of the configuration risks associated with the operation of a nuclear power plant and the approaches to control these risks using risk-based configuration control considerations. In that context, the actual and maximum potential configuration risks at a plant are analyzed and the alternative types criteria for a risk-based configuration control systems are described. The risk-based configuration calculations which are studied here focus on the core-melt frequency impacts from given plant configurations. By calculating the core-melt frequency for given configurations, the configurations which cause large core-melt frequency increases can be identified and controlled. The duration time in which the configuration can exist can then be limited or the core-melt frequency level associated with the configuration can be reduced by various actions. Furthermore, maintenances and tests can be scheduled to avoid the configurations which cause large core-melt frequency increases. Present technical specifications do not control many of these configurations which can cause large core-melt frequency increases but instead focus on many risk-unimportant allowed outage times. Hence, risk-based configuration management can be effectively used to reduce core-melt frequency associated risks at a plant and at the same time can provide flexibility in plant operation. The alternative strategies for controlling the core-melt frequency and other risk contributions include: (1) controlling the increased risk level which is associated with the configuration; (2) controlling the individual configuration risk which is associated with a given duration of a configuration; (3) controlling the time period configuration risk from configurations which occur in a time period