Application of a reduced order model to BWR corewide stability analysis

The determination of system stability parameters from power readings is a p roblem usually solved by time series techniques such as autoregressive mode ling. These techniques are capable of determining the system stability, but ignore the physics of the process and focus on the determination of a nth order linear model. A nonlinear reduced order system is used in conjunction with estimation techniques to present a different approach for stability d etermination. The simulation of the reduced order model shows the importanc e of the feedback reactivity imposed by the thermal-hydraulics; the dominan t contribution to this feedback is provided by the void reactivity, being a function of power, burnup, power distribution, and in general of the opera ting conditions of the system. The feedback reactivity is estimated from po wer measurements and used in conjunction with a reduced order model to dete rmine the system stability properties in terms of the decay ratio. (C) 2001 Elsevier Science Ltd. All rights reserved.