On 27 June the Russian fast reactor BN-800 reached first criticality, the Beloyarsk information centre reported. Fission was at a minimum power level, about 880kWh.

The 880MW Beloyarsk 4 reactor is the bigger sibling of the 600MW Beloyarsk 3, which has been operational since 1981. Both Beloyarsk 1 and 2 were shut down in the 1980s. Beloyarsk NPP is located in the Sverdlovsk region of the Urals, 45 kilometers from Yekaterinburg.

Already it is clear that everything happens in accordance with the design, so we have confidence that the BN-800 will work reliably, like its predecessor the BN-600," said director Michael Bakanov.

Construction on Beloyarsk 4 began in 2006 and fuel loading in February 2014. Now the next stage of commissioning testing begins before the unit starts power generation in October 2014, and begins commercial operation in 2015.

The fast reactor has sodium liquid metal coolant, and is envisaged to help Russia reuse uranium.