Conservative Tritium Exposure Assessment in the Atmosphere from the Spray Ponds of the Balakovo NPP

Atmospheric tritium discharges from nuclear power plants (NPPs) may have a significant impact on the population and should be constrained by radiation safety requirements. In this study we show that the spray ponds used for water cooling in some Russian NPPs are liable to state registration and regulation in accordance with national legislation. A comparison of possible conservative approaches to assess the intensity of tritium releases from the spray ponds was carried out using the example of the Balakovo NPP. Estimates of the evaporated water amount varied from 35 000 to 60 000 m³ over the 82-day period of stable snow cover in 2016–2017. These estimates corresponded to the total tritium activity discharged into the atmosphere during the evaporation from all spray ponds in the range from 5.2 × 10¹¹ to 9.7 × 10¹¹ Bq. The power of the source was from 7.4 × 10⁴ to 1.4 × 10⁵ Bq/s according to the thermodynamic and thermophysical approaches, respectively. The results of the investigation confirm the assumption that the spray ponds of the Balakovo NPP are a standardized source of tritium releases and should be constrained by setting airborne discharge limits.