Abstract: Sodium fluorescein method is one of on-site test methods for efficiency of HEPA filter of ventilation system in NPP, and some parts of the system are unavailable in the process of test. Based on analysis and verification of the method, improvement measures are proposed to shorten the unavailable state duration by increasing the aerosol mass flow and sampling flow of fluorescein sodium generator.

Key words: Ventilation system of NPP, HEPA filter, Sodium fluoresceinmethod