Electrochemical Corrosion Potential (ECP) Reduction and Crack Mitigation Experiences With NobleChem? and On-Line NobleChem?

摘要

NobleChem? and On-Line NobleChem? (OLNC) are proven technologies for potential mitigation of boiling water reactor (BWR) internals cracking. NobleChem? has been applied in BWRs since 1996 while OLNC has been applied in BWRs since 2005. Currently, there are 33 BWRs worldwide operating with NobleChem? with a total cumulative experience of over 250 reactor-operating years. The conventional NobleChem application requires 60 hours of critical path time and is performed just before plant shutdown, during hot standby mode, at a temperature of 115 to 148°C. On-Line NobleChem? (OLNC), the next generation technology, is an improvement of conventional NobleChem? . It is implemented while a BWR plant is operating and generating power, thus avoiding the need to have any critical path time for the application. OLNC has been applied in 6 BWRs thus far, and five of them had previously applied NobleChem?. Both NobleChem? and OLNC treated surfaces, in the presence of low levels of hydrogen, provide key benefits such as rapid ECP reduction and intergranular stress corrosion crack mitigation of BWR internals. This paper summarizes ECP reduction and IGSCC crack mitigation experiences with both NobleChem? and OLNC technologies in laboratory environments and in operating BWRs.