Treatment and conditioning of radwaste in nuclear power plants

Processing of gaseous radwaste

   
The processing of gaseous radwaste prior to its release into the atmosphere consists in cleaning the discharged emissions on special HEPA filters and on filters made out of active charcoal). The adsorption of gaseous fission products and their separation from gas occurs on these filters. However, molecules of noble gases are not irreversibly bound on the surface of active charcoal and after some time these products again appear at filter outlet. However, by choosing a suitable flow rate through the filters, such time of hold-up of gaseous fission products on filters is obtained during which decay of short-lived radionuclides can occur.       

    
It is then possible to release this gaseous radwaste under strict sanitary conditions into the atmosphere. The delay needed for short-lived radionuclides such as xenon and krypton is several days up to weeks, which can be achieved in practice. It is possible to reduce the total activity of gaseous radwaste with adsorption and hold-up by about two orders of magnitude.