Estimation of Reactivity and Average Fuel Temperature of a Pressurized Water Reactor Using Sliding Mode Differentiator Observer

This paper is about development of a uniform robust exact differentiator observer for estimation of the change in reactivity and average fuel temperature of a pressurized water reactor. The change in reactivity and average fuel temperature are important parameters in a nuclear power reactor, but there is no physical sensor available to measure these parameters directly. Therefore an observer is needed to estimate these parameters. There are different linear and non linear techniques to estimate the parameters with their own benefits and drawbacks. We have used uniform robust exact differentiator observer which is based on second order sliding mode and remains independent of initial conditions. This estimation is done under varying load conditions so that the estimated change in reactivity has the effect of control rod motion, coolant temperature and fuel temperature. For the proposed estimation scheme the measurement data of an actual plant is used. These measurements include normalized neutron density, coolant temperature and control rod position.