Das Projekt "Effectiveness and long-term behaviour of cleanable high efficiency aerosol filters" wird vom Umweltbundesamt gefördert und von Technischer Überwachungsverein Bayern Sachsen durchgeführt. Objective: Because of the high quantity of dust generated by various cutting/dismantling processes, frequent replacement of high-efficiency sub-micron particulate air filters is necessary. If such filters could be cleaned during service, costs for the replacement of the filters, radiation exposures and the amount of secondary waste could be reduced. The effectiveness in long-term operation (approx. one year) of high-efficiency sub micron particle air filters will be investigated in the framework of the dismantling of the Niederaichbach nuclear power station (KKN) in Germany. A high-efficiency sub micron particle air filter system will be exposed to heavy dust generation during the remote-controlled dismantling of KKN primary circuit pressure tubes, and therefore must be dedusted periodically. The dust is radioactively charged (essentially cobalt-60 and iron-55). The radioactivity could amount to approximately 1E5 Bq/g (pressure tubes and moderator tank) and the dose rate to 0.1 Sv/h. There is at present no experience on the effectiveness and the long-term behaviour of high-efficiency sub micron particle air filters that are dedustable during operation. General Information: WORK PROGRAMME: 1. Installation of the filters; 2. Determination of the main parameters of the clean filter station; 3. Continuous measurements (pressure pickups, air humidity and temperatures) during cutting of KKN primary cooling circuit (activated cooling channel tubes inside the reactor vessel); 4. Final evaluation including radiation exposure of workers, secondary waste arisings, specific costs, effectiveness and long-term behaviour of the filter system. Achievements: Because of the high quantity of dust generated by various cutting/dismantling processes, frequent replacement of high efficiency sub micron particulate air filters is necessary. If such filters could be cleaned during service, costs for the replacement of the filters, radiation exposures and the amount of secondary waste could be reduced. The effectiveness in long term operation of high efficiency sub micron particle air filters is investigated in the framework of the dismantling of the Niederaichbach nuclear power station (KKN) in Germany. ...