Steam Generator Secondary Side Chemical Cleaning During Reactor Plant Cooling Down

For safe and reliable operation of NPP steam generators, it is required to remove the sludge from heat exchanging tubes and steam generator (SG) volume in due time. Chemical cleaning technology of SG secondary side during NPP cooling down will be used in Tianwan NPP, which was used to remove iron and copper oxides from steam generators secondary side in Russia NPPs and to resume the heat exchange capacity of heat exchange tubes. To validate and evaluate the effectiveness and safety of the SG cleaning formula during NPP cooling down provided by Russia (RF) for Tianwan NPP, cleaning effective tests and safety tests were done in autoclave with the chemical cleaning process parameters simulated. To compared with RF, cleaning effective tests and safety tests were done with A₃B₁ under the same condition. Cleaning effective test results showed that the simulated sludge for Tianwan NPP can be more effectively dissolved and removed with A₃B₁ than with RF. Cleaning safety test results showed that the general corrosion amount of 0Cr18Ni10Ti stainless steel was very low but the general corrosion amount of SA508-III steel was high both with A₃B₁ formula and the formula provided by Russia.