Implementation of a new suboptimal robust control in an old plant - safety aspect

The paper considers the safety aspect of the retrofit of an additional control system in an old PWR nuclear power plant. The basic purpose of the additional multivariable robust controller in the old plant is to provide improvement integration of existing automatic feedback control loops. The design enables the control of a wider variety of disturbances and the plant will experience fewer spurious shutdowns and reduced demand for the protection system. As safety criteria, the stability of the plant using recently developed methods for stability analysis, is considered. Stability of the plant subject to large parameter variations in the system dynamics, as well as stability in case of different failures of the additional computerized control is examined. Numerical computation and simulation presented in the paper refer to nuclear power plant of Krsko, Slovenia. (author)