In 1985, at Novovoronezh NPP (NVNPP), liquid radioactive waste leaked from the storage facility No2 (SLW-2). The leakage took place along the perimeter of the storage facility from the underpan closed with soil; therefore the leakage has been discovered in about half year, during water sampling from the test boreholes. According to the assessments, a volume of liquid waste released in soil was about 480 m3 with ∼76 and 15 TBq activities of 60Co and 137Cs, respectively. Up to now, the majority of 137Cs amount has been localized at the place of the leakage – in the unsaturated zone at the level of the underpan; 60Co was infiltrated into the aquifer and spread through – ground waters at about 700 meters up to Don River. 60Co occurrence in the river was registered in 1995. The ground water discharge into Don River caused contamination of some part of bottom sediments up to the level of solid radioactive waste. This paper presents the calculation results of 60Co migration via ground waters.