DEAERATION OF NUCLEAR REACTOR WATER

PURPOSE:To enable a more effective deaerating operation in an initial operation stage and elimination of generation and bringing-in of radioactive materials by utilizing an operational heat of nuclear reactor internal recirculation pumps as a heating source for a deaeration of nuclear reactor water. CONSTITUTION:In case that nuclear reactor water is deaerated during a reactor start up, internal pump 3 are started up for the first place. Then the reactor water is heated up by an operational heat of the pump 3 started up in this procedure. By this heating up, a concentration of dissolved oxygen DO in the reactor water decreases to almost nothing. In this case, no O2 resulting from a radioactive decomposition of the water is generated because no radioactivity is generated in a reactor core 2. Accordingly, an deaeration efficiency is much improved and a required DO value can be attained shortly being assisted by an agitation effect of the pumps 3. Also vapor and non-condensing gas containing O2 dissolved in the reactor water, which are generated during this process, are ejected by a vacuum pump 16, are treated by an off gas treatment system 13 and are discharged to the atmosphere from a stack 14. In this case, because there is no nuclear heating, a deaeration can be effectively done by a pump 16 which does not belong to the treatment system 13.