Knowledge base expert system control of spatial xenon oscillations in pressurized water reactors

Abstract

Current xenon oscillation control methods used in pressurized water reactors are knowledge intensive, and heuristic in nature. An expert system is developed to implement the heuristic constant axial offset control procedure to aid reactor operators in increasing the plant reliability by reducing the human error component of the failure probability. An expert system is written in the production system language, OPS5, with a forward chaining algorithm. It samples the reactor core with a certain time interval, evaluates the core status to determine the necessary corrective actions in terms of reactivity insertion, and selects the control parameter to realize this reactivity insertion. The amount of control action is determined using a knowledge base which consists of the differential rod worth curves, and the boron reactivity worth of a given reactor. The controller has been tested using a one-dimesional core model for verification of the rules and the code. It has been shown that, having the reactor dependent parameters in its knowledge base, the controller is able to follow a typical load demand for a daily cycle of a reactor, and is able to keep the axial offset within a target band.