The BN-800 reactor was brought to minimum controlled power for the first time in June 2014, at which time commercial operation was planned for the end of that year. However, in December 2014 Rosenergoatom announced that nuclear fuel for the unit would first be developed further. It was brought again to the minimum controlled power level in August 2015, and again in November 2015, eventually being connected to the grid on 10 December 2015.
Since the beginning of this year, during its ascent to full power, Beloyarsk 4 has generated more than 1.3 billion kWh of electricity. It is planned to produce 3.5 billion kWh during the whole of 2016.
The 789 MWe BN-800 Beloyarsk 4 is fuelled by a mix of uranium and plutonium oxides arranged to produce new fuel material as it burns. Its capacity exceeds that of the world's second most powerful fast reactor - the 560 MWe BN-600 Beloyarsk 3.
The BN-800 core with metallic fuel should have an average burnup 80 MW·days/kg. (fuel burn-up of 70-100 GWd/t). Normal light water reactors now have about 50 Gigawatts per day per ton of fuel, and new LWR will have about 65 GWd/t and annular /cylinder shaped for better hear management fuel will enable older reactors to have higher burnup. A followup russian fast reactor could have 120 GWd/t fuel burnup
Russia plans to build two BN-1200 reactors by 2030
Here are some specs on the BN-800 and a prospective BN-1200
SOURCES- IAEA, wikipedia, World Nuclear news