Investment requirements and reduction of overall plant efficiency are even greater if dry cooling is adopted: the estimated cooling system investment costs of dry cooling are about 3-4 times higher than those for wet cooling. For essential service water, the system must be capable of cooling the plant under the worst conditions for 30 days, with a minimal flow rate of 1 m3/s. With an open circuit, a water reserve of 3 million m3 should be available. Other chemical waste is produced by the demineralisation plant, the laundry and cooling water treatment (monochloramine, sulfuric acid, chlorine), depending on the characteristics of the raw water.