Abstract: Nuclear power plant, including a steam generator having a secondary circuit including a steam-energy converter with a first return line for condensate of relatively lower temperature and a second return line for condensate of relatively higher temperature, a mechanically acting filter disposed in the first return line, an electro-magnetically acting filter disposed in the second return line, and a by-pass line having a cut off element disposed therein and originating from the second return line and discharging at a location in the first return line upstream of the mechanically acting filter, and a method for the operation of the power plant.