Development of air conditioning systems for reducing emission from nuclear power plants

Fan systems and their configurations for maintaining underpressure in sealed spaces of WWER type nuclear power plants are reviewed. The systems are of through-flow or circulation types. The first development type of the systems was based on permanent venting at a capacity of about 10,000 m3.h-1 and achieved an underpressure of 100 to 150 Pa. Upon underpressure decay and at a pressure of 30 Pa, all air supply and discharge valves were closed within 15 s. The second development type had a capacity of 1,000 m3.h-1 of inlet air. The sucking system capacity was higher by 150 m3.h-1, which gave an underpressure of 150 to 200 Pa. In the event of an accident or pressure increase to 30 Pa in the sealed zone, the quick-acting valves close within 3 s. The third development system operates at an air capacity of 3,000 m3.h-1 and maintains an underpressure of 150 to 200 Pa. The quick-acting valves close within 3 s. The systems are also described of sealed space venting during repairs and refuelling, the systems for emergency venting, and the systems for trapping harmful materials during operation of nuclear installation, especially aerosol filters and filters for the capture of iodine and methyl iodine. (J.B.). 7 figs