Effects of curative and preventive chemical cleaning processes on fouled steam generator tubes in nuclear power plants

摘要

Magnetite (Fe3O4) deposits in the secondary circuit of nuclear pressurized water reactors (PWRs), lead to the fouling of the steam generators (SG) which decreases their thermal performances and increases the risk of corrosion of the SG tubes. As a counteraction, preventive and curative chemical cleanings (CCC) are industrially implemented to remove oxides sludges and deposits in SGs. The use of chelating agents in chemical cleaning processes could affect the passive layer of SG tubes, and modify their surface reactivity. In order to better understand these phenomena, two experimental loops have been designed and operated: the FORTRAND loop to perform and investigate SG tube oxidation, fouling and refouling and the ECCLIPS loop used to investigate the effects of the chemical cleanings.