Patent Number: 039322122
Section: claims

1. Method for depressurizing, degassing and affording decay of weakly radioactive condensates in a steam nuclear power plant of the type having a turbine with higher and lower pressure stages and a main condenser for condensing exhaust steam from the turbine to a main condensate, and at least one feed-water preheater heatable by bleeder steam fed thereto from a higher pressure stage of the turbine, the condensate of said bleeder steam constituting a secondary condensate, which comprises the steps of: feeding the secondary condensaate at a higher temperature and higher pressure than the main condensate into the main condensate so that the secondary condensate vaporizes in the main condensate with simultaneous degassing of the main condensate by the vaporizing of the secondary condensate, and thereafter passing both main and secondary condensates through a flow path of sufficient length to permit the radioactivity to decay. 2. The method of claim 1 including the step of first feeding the secondary condensate to a pressure relief chamber while still maintaining said secondary condensate at a higher pressure than said main condensate. 3. Method according to claim 2 which includes conducting the feed-water through a flow path that bypasses the preheater, heating the bypassing feed-water by means of bleeder steam from a higher pressure stage of the turbine thereby to produce additional secondary condensate, feeding the additional secondary condensate to another pressure relief chamber and feeding the additional secondary condensate from the other standpipe into the main condensate wherein the additional secondary condensate vaporizes. 4. Apparatus for depressurizing, degassing and affording decay of weakly radioactive condensates in a steam nuclear power plant of the type having a turbine, a main condenser for condensing exhaust steam from the turbine to a main condensate, a tank for collecting the main condensate below the level of the turbine, and at least one feed water preheater heatable by bleeder steam fed thereto from a higher pressure stage of the turbine, the condensate of said bleeder steam constituting a secondary condensate that is at higher temperature and higher pressure than the main condensate because of the origin thereof from said higher pressure stage of the turbine, comprising: a plurality of degassing channels each provided with a lateral overflow, said channels being provided in the upper part of the collecting tank for filling with the main condensate up to the level of the overflows, horizontal feed pipes arranged in said channels below the overflows, at least one pressure relieving standpipe for receiving said secondary condensate, said horizontal feed pipes communicating with said standpipe and having openings at a lower portion thereof, said collecting tank having a lower part provided with partitions having cutouts which are staggered relative to one another thereby to provide a flow path of sufficient length to permit the radioactivity of the condensates to decay, and a run-off sheet communicating between the upper and said lower part of said collecting tank. 5. Apparatus according to claim 4, comprising air cooler units for the main condensate which cause the main condensate to become oxygen-enriched, run-off baffles arranged to conduct the oxygen-enriched main condensate to certain ones of said degassing channels, means for conducting the remaining main condensate to other ones of said degassing channels, whereby a mixing of the oxygen-enriched main condensate and the remaining main condensate takes place on the run-off sheet. 6. Means for the depressurizing, degassing and decay of weakly radioactive condensates in nuclear power plants of the type having a turbine, and a main condenser for the exhaust steam of the turbine whereby the exhaust steam condensed in the main condenser forms a main condensate and a collecting tank for the condensate is situated below the condenser and a source of secondary condensate: comprising a plurality of horizontal degassing channels which have a lateral overflow arranged in the upper part of said condensate collecting tank and adapted to be filled with the main condensate up to the level of the overflow, horizontal feed pipes extending in said channels below the overflow height of the degassing channels, said feed pipes being provided on their underside, with discharge openings for the bubbling of the secondary condensate into the main condensate. 7. Apparatus as in claim 6 wherein said condensate collecting tank has partitions which are provided with mutually displaced partitions in order to provide an adequately long path for the decay of the main and secondary condensates, the condensate which is discharged from the condensate collecting tank being returnable into the cycle as feed-water.