Stability Monitoring Tests Using a Nuclear-Coupled Boiling Channel Model

Abstract

A new test platform for stability studies is presented that can be used to generate a power time series, which in turn may be used to validate the capability of boiling water reactor stability-monitoring algorithms. The thermal hydraulics for boiling channels are modeled and coupled with neutron kinetics to analyze the nonlinear dynamics of the closed-loop system. The model uses point kinetics to study core-wide oscillations, and it couples two time-domain calculations, for the fundamental and first harmonic modes, to study out-of-phase oscillations. The channel coolant flow dynamics is dominant in the power fluctuations observed by in-core nuclear instrumentation, and additive white noise is added to the solution for the channel flow in the thermal-hydraulic model to generate a noisy power time series. Autoregressive analysis performed with the computer-generated series agrees with the stability properties of the boiling channel. The operating conditions of the channel can be modified to accommodate a wide range of stability conditions.