The tests of the newest emergency cooling system of the reactor core that is a part of the large-scale modernization operations have been successfully completed at the fourth power unit of Novovoronezh NPP (NV NPP). This system has been implemented for the first time since the beginning of operation of VVER-440 reactor power units.

It’s unique because together with an active cooling system it also uses the passive one. For this purpose, a special building was built on the industrial site, where four hydraulic reservoirs of Russian production, with a volume of sixty cubic meters each, are installed. They are filled with boric solution and have underground connection with the rector’s primary circuit. If the pressure in the primary circuit becomes lower than the pressure in the reservoirs, the boron water enters the core and cools it. This gives time to run security systems that require power supplies.

“Tests have confirmed the design characteristics of this modern security system. The passive system requires neither a signal from control systems, nor a source of energy. The equipment will perform its function exactly at the moment when it is needed. It is due to the laws of physics, which are always in effect and which cannot be ignored”, the Deputy Chief Engineer for operation at the Phase 2 of NV NPP Andrey Meremyanin said.

Testing of the core emergency cooling system is one of the key stages of large-scale modernization of the power unit No 4 with VVER-440 reactor. In total, more than 40 operations are planned within the framework of the service life prolongation of the NV NPP 4th unit. After they are over, the life of the renewed power unit will be extended for another 15 years, and will reach 60 years in total.

There are six such power units in Russia: two at Novovoronezh NPP and four at Kola NPP. They are also built in Armenia, Bulgaria, Hungary, Germany, the Czech Republic, Slovakia, Ukraine, and Finland.