Ostrovets plant begins physical start-up
Unit 1 of the nuclear power plant under construction in Belarus has achieved first criticality, Russia's Rosatom announced today. The milestone was reached at 2.26am (local time) on 11 October. First criticality, also referred to as the minimum controlled power level, is reached when neutron flux is recorded in a reactor at a level sufficient to sustain a fission chain reaction. It is considered to be the final stage of the physical start-up procedure, and enables personnel to verify whether the physical characteristics of the reactor core comply with the design requirements.