<p><i>Background:</i> For confirming the compliance with the radiation quota from nuclear emissions to atmospheric air, the annual radiation dose should be calculated as the sum of doses from short-term emissions during scheduled preventive maintenance (SPM) and continuous emissions for the remainder of the year.</p><p><i>Aim:</i> To obtain experimental data on the quantitative and qualitative composition of radioactive atmospheric emissions during the SPM at the power unit No.&#xa0;3 of the Balakovo nuclear power plant.</p><p><i>Materials and methods:</i> Daily determination and identification of the radionuclide emission dynamics using the previously developed radiological engineering method of survey was carried out during the transition from the standard operation of the power unit to the opening and decompression of the containment.</p><p><i>Results:</i> The activity of ³H, ¹⁴C, ¹³¹I, and radioactive noble gases released into the atmospheric air during the maintenance is 1–2 orders of magnitude higher than the emissions for the reminder of the calendar year (without repairs).</p><p><i>Conclusion:</i> The obtained experimental results on the activity of radioactive substances during the SPM at the power unit No.&#xa0;3 of the Balakovo nuclear power plant can be used to develop an approach to calculating the annual radiation dose from both short-term emissions during the SPM and continuous emissions in the remainder of the year. This approach will be presented in the publication “Radionuclide emissions of the Balakovo nuclear power plant during scheduled preventive maintenance with the assessment of the population radiation dose. Part&#xa0;2”.</p>