Mathematical Modeling and Strategy for Utilizing the Remaining Resource of Flow Meters in Shutdown RBMK Power Units during the Decommissioning of Nuclear Power Plants

During the decommissioning of nuclear power units with RBMK reactors, in addition to the energy resource of unburned fuel, there remains an unutilized operational resource (service life) of instruments, equipment elements, and other components in the shutdown units. Under certain conditions, this resource can be used in operating power units. An example of this is the remaining service life of coolant flow meters. The problem arises of optimizing the utilization of this resource. This study presents a mathematical model for predicting changes in the service life of flow meters, with consideration of the probability of their failure and technological constraints on maximum operating hours. Various strategies for using the flow meter resource are examined in accordance with the planned sequential decommissioning of power units. Numerical studies allow the selection of the optimal strategy. It is shown that the savings effect from reusing flow meters depends on the assigned maximum operational time and can range from 40 to 100%.