Experience with the upgraded VERONA-u WWER-440 core monitoring system

The paper describes the components, functioning and services of the VERONA-u core monitoring system recently installed at Unit 2 and 3 of the Hungarian Paks NPP. The VERONA-u is a totally upgraded and modernized version of the previous VERONA system, in the upgrading project the data-concentrator, the host computer and the operators' displays were replaced by state-of-the-art hardware and software components. Dual hardware redundancy and automatic function recovery actions were introduced in order to ensure high system availability. The man-machine interface has been redesigned completely, applying X Windows as Graphical User Interface. Improved core analysis and power reconstruction methods were introduced, together with a detailed hot-spot monitoring algorithm. A capable archivation module ensures periodic logging of all measured data, change sensitive storage of important signal changes and provides sophisticated post-mortem analysis tools. The upgraded system has been working satisfactorily on Unit 2 for a complete fuel cycle by now, the on-line system response in complex, transient situations is illustrated in the paper. (author). 10 refs, 4 figs