METHOD OF CLEANING THE HEAT EXCHANGE SURFACE OF ATOMIC POWER STATION STEAM GENERATOR WITH WATER-COOLED POWER REACTOR (ITS VERSIONS) Russian patent published in 1994 - IPC

FIELD: heat power engineering. SUBSTANCE: depositions of the heat exchange surface of steam generator are washed off with solution of complexone in course of cooling the reactor plant. Two versions of cleaning are suggested. According to the first version, at temperature of heat-transfer agent of second loop of 180 to 200 C, the following solutions are fed to steam generator in order to create in its volume concentration of complexone not lower than 10 g/kg at pH of 3.5 to 6.5: solution of oxyethyliden-diphosphonic acid or ethylenediamine-tetraacetic acid or their salts and weak acid, best of all oxalic acid. At temperature of 120 to 140 C, oxidizer is additionally introduced, best of all hydrogen peroxide to a concentration of 1.0 to 5.0 g/kg in the steam generator volume. The second version of cleaning is used for cleaning the heat-exchange surfaces affected by heavy tightly stuck deposits. At temperature of heat-transfer agent of the second loop of 180 to 200 C, solution of oxyethyliden-diphosphonic acid or ethylenediamine tetraacetic acid of their salts and weak acid is fed to steam generator to create concentration of complexone in its volume not lower than 10 g/kg at pH of 3.5 to 6.5. At temperature of 140 to 170 C, the cooling process is discontinued for an hour as a minimum. Then, the cooling process is continued and at temperature of 120 to 140 C, additional amount of complexone and oxidizer is introduced in steam generator to create in its volume concentration of complexone of at least 2 g/kg and oxidizer of 1 g/kg. It is good practice to use oxalic acid as weak acid. EFFECT: enhanced efficiency. 4 cl