Russia’s BN-800 sodium-cooled fast reactor at unit 4 of the Beloyarsk NPP has resumed operation after the first scheduled maintenance carried out as part of the equipment preparation for full commercial operation. The unit was first connected to the grid on 10 December 2015, since when power has been built up gradually to enable tests and checks to be carried out on equipment and systems at different power levels under different operational modes, the plant said. The first scheduled maintenance outage began on 27 June to allow an in-depth inspection of all equipment to prepare the power unit for integrated trials at the rated power and subsequent acceptance for commercial operation, which is planned for the autumn. During maintenance the electric motor of the reactor coolant pump of the primary circuit was replaced. In the turbine department an innovative ball cleaning system was installed to remove deposits on the inner walls of tubes in the turbine condensers. Some valves and gates were replaced, which had been used on a temporary basis during pilot commercial operation.