ICONE23-1945 CORE MONITORING AND SURVEILLANCE OF THE RUSSIAN VVER-440 TYPE OF REACTORS IN CZECH REPUBLIC AND SLOVAK REPUBLIC

Abstract

During the 70' and 80' of the last century 12 units of Russian VVER-440 type of reactors were started to build on the territory of Czech and Slovak Republic. Nowadays 2 units were already shutdown, 8 are operates and 2 are still under construction. During theirs operation period wide range of modifications and upgrades were performed to strengthen the nuclear safety and reactors operability. In scope of strengthening the reactor's core monitoring and surveillance the original Russian VK3 system was completely replaced with advanced computer based core monitoring and surveillance system SCORPIO-VVER developed by the local organizations with international support. Since 1999 up to today the SCORPIO-VVER system were installed and still operating on four units of Dukovany NPP (Czech Republic), on two units of Bohunice NPP (Slovak Republic) and on the full scale plant training simulator at the Centre for training and education of the reactor operators and reactor physicist in Trnava (Slovak Republic). With the first installation in 1998 at Dukovany NPP the SCORPIO-VVER system has proved to be a valuable tool for the reactor operators and reactor physicists and was licensed by both Czech and Slovak Nuclear Regulatory Bodies as a Plant Technical Specification Surveillance Tool. The development of SCORPIO-VVER core monitoring system continues along with the changes in VVER reactors operation. Within the planned upgrades the system is being adapted according the utility needs. Between the most significant upgrades and changes belongs the modifications in connection with implementation of a new digital I&C system, adaptation of the system to up-rated unit conditions, loading of the optimized Gadolinium bearing Gd2M+ fuel assemblies, improvements in the area of core design (neutron physics, core thermal hydraulics and fuel thermal mechanics), in design and methodology of the limit and technical specifications checking (on-line shutdown margin calculation) and improvements in the predictive part of the system (Strategy Generator). The latest upgrade of the SCORPIO-VVER system at Dukovany NNP is under progress with the planned end in December 2015. The system is being completely renewed, re-hosted to the new hardware, being implemented the latest advanced neutron-physical and thermo-hydraulical codes with enhanced accuracy in accordance with local, national and international standards and requirements.