Development of a BWR control rod pattern design system based on fuzzy logic and knowledge

The development of a system for the control rod pattern design of Boiling Water Reactors based on fuzzy logic and knowledge is presented in this paper. The fuzzy logic module makes use of membership functions and fuzzy rules to control the neutron multiplication factor and the maximum relative nodal power by acting over the control rodsʹ relative movement and the in-core water flow. The Mamdani implication process is used to evaluate the membership functions. The multiplication factor is controlled in order to bring the reactor to the critical state, and the maximum relative nodal power is controlled to maintain the main thermal limits in the core under their design values. Knowledge rules are implemented to govern the control rodsʹ movement and the coolant flow in the core. The fuzzy logic control system is linked to the three dimensional neutronic and thermal-hydraulic steady state simulator CM-PRESTO. The system was tested with the cycle 10 of Laguna Verde Nuclear Power Plant, Unit 1. The results obtained show that a very reasonable control rod programming can be achieved with a quite simple methodology. The obtained cycle length is comparable with that achieved with a Haling based simulation.