Commissioning risk analysis for annular space ventilation system of nuclear power units

 The annular space ventilation system of nuclear power units is used to maintain negative pressure in annular space to ensure that air from inner containment is filtered before discharge, in order to reduce the release of radioactive materials to the environment. Points out that the greatest commissioning risk of the annular space ventilation system comes from the commissioning of the automatic frequency conversion control system, internal and external factors affecting the commissioning of automatic frequency conversion control system shall be considered in advance and formulate corresponding control measures.