The RBMK-1500 is fueled by a graphite-moderated, water-cooled reactor core having a thermal power generation capacity of 4800 MW. It is designed to provide saturated steam at a pressure of 7.0 MPa. The fuel is low enrichment UO2 which is loaded into the core in the form of zirconium clad, 13.6 mm diameter fuel rods. Initial enrichment was 2%, since 1997 reload fuel is 2.4%. Fuel clusters are made up of 18 such rods and each is positioned in an individual vertical fuel channel. There are 1661 vertical fuel channels having an active fuel length of 7 m. Design fuel burnup is 21.6 MWdays/kg though presently this can be lower because of safety-imposed restrictions related to minimizing of the steam reactivity coefficient. The real fuel burnup is about 12-16 MWdays/kg for loading of fuel with 2% enrichment, and not less 21 MWdays/kg for loading fuel with 2.4 % enrichment. The fuel clusters are cooled by water which enters at the bottom at a subcooling of 30 oC and exits the channels at an average steam volume fraction of about 76%. Nominal coolant flow rate at design power is 10000 kg/s.