Unit 2 of nuclear power plant in Belarus attains first criticality 

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Unit 2 of the first nuclear power plant (NPP) in Belarus attained its first criticality, or controlled self-sustaining nuclear fission chain reaction, last week, according to a statement by the Russian state atomic energy corporation Rosatom.  

The 1,200 MW first unit of the Belarus NPP, equipped with the state-of-the-art VVER-1200 reactor and being built with the assistance of Rosatom, started commercial operations in June 2021.  

“On March 25, the reactor of power unit 2 of Belarus NPP was brought to minimum controllable power level. The neutron flux was registered for the first time, and a controlled self-sustained nuclear reaction began,” Rosatom said.  

Achieving the minimum controllable power level of less than 1 percent of the rated power makes it possible to proceed to the final part of tests of the physical start-up stage of the power unit, the statement said.  

“To confirm compliance with the design and clarify the rated neutron and physical characteristics of the reactor first fuel loading, the specialists will take measurements of the actual state of the core.  Reliability of functioning of protections, interlocking and the entire nuclear physical control and nuclear safety systems of the reactor plant will also be checked,” it added.  

Once these checks and results have been considered by the nuclear regulator of Belarus and a start-up permit issued, a gradual increase of the power will begin. According to the Energy Ministry of Belarus, the next steps will be to increase the power of the reactor plant to 40 percent or more with the first trial connection of the unit to the network and subsequent tests in different modes. 

The VVER-1200 reactor has several advantages when compared to the previous generation VVER-1000 reactor, including a unique combination of active and passive safety systems. VVER-1200 power units are equipped with a “core catcher” – a device designed to contain and cool the melt of the reactor core in the event of an accident – as well as other passive safety systems capable of operating without the participation of personnel in the event of a complete power outage, according to Rosatom.  

The Belarus NPP, located at Ostrovets, is the first VVER-1200 project to become operational outside Russia. Once fully completed, the twin unit 2,400 MW project is expected to supply over 18 billion kilowatt hours (kWh) of low-carbon electricity to the country’s national grid every year. 

The VVER-1200 reactor is also the backbone of the Rosatom export order book consisting of 34 units across 11 markets, including Finland, Hungary, Uzbekistan, Turkey and Bangladesh.