4.84. During normal plant operation, a ventilation system should be operated to maintain the pressure, temperature and humidity in the containment atmosphere within the limits specified in the design on the basis of the assumptions and results of the safety analysis. These limits should be in compliance with the equipment qualification parameters. Appropriate monitoring of the activity of the exhausted air and appropriate filtering should be provided.

4.85. In some designs the need may arise for a periodic purging of air because of the buildup of pressure caused by leaks from instruments and service air systems. In this case, appropriate monitoring of the content of radioactive material of the exhausted air and appropriate filtering should be provided.