Improving crud removal performance of deep bed type condensate polisher with small size ion exchange resins at BWR plant

In BWR power plants, the principal objective and functions for the installation of the deep bed type condensate polisher is to remove both ionic impurities caused from sea water leakage and suspended impurities called 'crud' mainly consisting of metal oxides which are produced from metal corrosion. In considering the reduction of occupational radiation exposure level, it is extremely important to remove the crud effectively. In recent Japanese BWR power plants, condensate pre-filters with powdered ion exchange resins or with hollow fiber membrane have been installed to remove the crud at the upper stream of the condensate polishers. In such plants, the crud removal is conventionally the secondary objective for the condensate polishers. Since April 1985, the Japan Atomic Power Company had introduced the small mesh size ion exchange resins and then developed a soak regeneration method at Tokai No. 2 Power Station, to improve the crud removal performance by using only condensate polishers without any condensate pre-filter, and as a result achieved below 1 ppb as Fe, as expected. (author)