It was just a beginning of Coronavirus pandemic restrictions in Europe when VUJE completed delivery of brand-new manipulator for remote controlled plugging of VVER-440 steam generator heat exchanging tubes. Whole project begun one year earlier in spring 2019. Based on extensive experience with development of this kind of equipment VUJE presented turnkey solution, customized to Hungarian Paks NPP requirements. Since very beginning of design stage until final assembly we were in close contact with Paks NPP specialists to be sure that all requirements of our customer are fulfilled. Brand new system, beside manipulator ZOK itself, includes also automated drying system, mobile container for all tools and accessories, portable control unit and testing stand. Whole plugging procedure involves operations like drying of the steam generator collector internals, cleaning of the surface around the heat exchanging tube, drilling of the opening for a plug, insertion and orbital welding of the plug as well as visual inspection of the weld. System is designed also for situation when a plug is found to be defective and must be replaced. Special plug repair procedures were developed and tested for variety of plugs; factory plugs as well as manual plugs used before automated plugging was introduced. Thanks to intensive evolution of electronics and technology, plugging and plug replacement process have evolved to higher level of efficiency and reliability.

Before the system was delivered to power plant, together with Paks NPP specialist it was tested in VUJE. All its functions and capabilities were thoroughly verified. After delivery an extensive training of the maintenance personnel was performed in Paks NPP training center in real conditions and real steam generator. All works were successfully completed just in time and few hours before Coronavirus pandemic restrictions were introduced among European countries.

Design team in VUJE has more than 30 years of experience with design and development of inspection and maintenance manipulators for WWER steam generators. Since the very beginning of 21st century when automated plugging technology was introduced to NPPs, VUJE have developed 3 generations of plugging systems and delivered already 13 systems to 10 nuclear power plants with WWER units in 5 countries. The latest one is manipulator ZOK – OPZ 19 awaiting its first deployment during an outage in November 2020 in Paks NPP.