This paper discusses the technical, economic and operational issues addressed in improving RO feedwater to acceptable standards for the Point Beach Nuclear Plant. The final design, incorporating membrane filtration, resulted in a more economical and reliable system to operate and allowed full utilization of the capacity of the RO system.
We Energies' Point Beach Nuclear power plant, in operation since 1970, is a 1,036-megawatt, two reactor base-load facility located on Lake Michigan in Two Rivers, Wis. Nuclear Management Company, based in Hudson, Wis., assumed operation of the plant for We Energies in 2000, and also operates five other nuclear power plants in the upper Midwest. In 1970, We Energies was using the most widely accepted technology for demineralized make- up water. The original water treatment design consisted of intake screens; lime-softening solids contact clarifier, one multimedia filter, two cation exchangers, one vacuum deaerator, two anion exchangers, and a polishing mixed-bed demineralizer, as shown in Figure 1.
Figure 1: Original Water Treatment System
ANION DEGAS ANION CATION DEGAS MIXED BED CATION MIXED BED
Poor make-up water quality, coupled with inadequate steam-system chemistry control, caused internal corrosion of the Unit 1 steam generators. The generators required replacement in 1983 after only 13 years of service, at a cost of nearly $90 million. In 1985, a 75,000-gallon lime softening solids contact clarifier was installed to replace the original 15,000-gallon clarifier, three multimedia