Estimation of precursor density of a power reactor using uniform second order sliding mode observer

In this paper a uniform second order sliding mode observer is used to estimate the precursor density of a pressurized water reactor (PWR). Precursors produce delayed neutrons which are most important in control of nuclear reactor, but cannot be measured directly. This estimation is done under varying load conditions and taking into account the effects of reactivity feedback due to temperature. For the proposed estimation scheme the measurement data of Chashma Nuclear Power Plant Unit-1, Pakistan is used. These measurements include neutron density, coolant temperature and control rod position. Before the estimation a model of 998 MW (thermal) pressurized water nuclear power reactor is validated with experimental data because the mathematical model of plant should be accurate and precise for parameter estimation as well as controller design. Measured neutron density and modeled neutron density are compared and found close to each other. Further more measured and modeled coolant temperatures are also compared. The response of mathematical model coincides with actual plant with minor error. This error may be due to uncertainties and unmodeled dynamics.