[en] To guarantee radiation protection and nuclear safety, ventilation systems in nuclear power plants during normal operation and during operational states deviating from the normal have important functions to fulfill. Based on a standard drafted by CMEA member states, technical principles were worked out and agreed. These principles may be defined as binding by the National Board for Atomic Safety and Radiation Protection in the licensing procedure in accordance with article 4 of the Ordinance on the Implementation of Atomic Safety and Radiation Protection dated 11 October 1984