NobleChemTM application during power operation for crack mitigation and dose rate reduction of BWRs

NobleChemTM is a technology that has been accepted by the BWR industry as a means to lower ECP with low hydrogen addition, thus satisfying the criteria needed for stress corrosion cracking (SCC) mitigation. Currently, 31 operating BWRs have applied NobleChemTM and the total cumulative NobleChemTM experience is in excess of 150 reactor operating years. The conventional NobleChemTM technology requires the injection of a mixture of platinum and rhodium chemicals into the reactor at a lower temperature of 115 to 143oC, and takes about 60 hours of critical path time. Recently, GE developed and implemented a more effective new generation On-Line NobleChemTM application (OLNC) that can be employed while the BWR is operating at full power, and hence eliminates the costly critical path time requirement. Furthermore, the OLNC application is not outage related, is transparent to plant operations, and requires the use of platinum chemical only. The first OLNC application was completed in an operating BWR in July 2005 followed by a second OLNC application in the same plant in January 2006. The application was successfully completed with no impact on operating dose rates, no impact on plant operations and no unexpected changes to water chemistry parameters. This paper presents the application results and the encouraging drywell dose rate and shroud ultrasonic (UT) crack growth rate data following the second OLNC application. (author)