As a fundamental VVER design principle, all major safety systems are equipped with both active safety systems (backed by highly reliable AC and DC power supplies with redundant sources), and passive safety systems, which require no electrical power at all.
The safety design features of the VVER allows operators the possibility of using different safety systems independently of each other and in a flexible manner, depending on the accident scenario.
In other words, despite the presence of passive systems capable of automatically (without operator intervention) handling virtually any conceivable
disruption, there are also backup active safety systems that operators can engage if necessary. For example, a system for spraying coolant onto containment equipment, or injecting neutron-absorbing boric acid into the reactor to suppress reactivity.
The well-thought-out combination of reliable passive systems with faster active systems in the VVER design allows for the reliable and rapid mitigation of accident consequences. The VVER-1200 features particularly well against the AP1000 and the EPR.
The VVER-1200 also features an additional level of safety thanks to a passive heat removal system from Steam Generators (SGs), which provides emergency cooling of the primary circuit through natural steam circulation — where the steam condenses either through the boiling of water at atmospheric pressure or through heat exchange with arranged air circulation.
Across a wide range of possible accident scenarios VVER-1200s are capable of operating … [download the Nuclear Insights Volume to read further]
