Galvanic corrosion test measurements zircaloy process tube hydriding problem

摘要

In September of 1965, a program was launched to investigate the cause and to determine appropriate corrective or preventive action for hydriding of Zircaloy process tubes in K Reactors. One phase of the investigation was specifically directed to the measurement of galvanic corrosion currents flowing between the Zircaloy process tube and the aluminum spacers. Production Test IP-807 authorized in-reactor galvanic test measurements in order to secure data relating to the hydriding problem. It is the purpose of this report to document all the galvanic corrosion current data recorded for tests in K Reactors during the investigation of the hydride problem. The galvanic potentials recorded for test measurements in the K Reactor process tubes, identifies the approximate location and magnitude of the corrosion currents generated between aluminum spacers and Zircaloy process tube. The flow of galvanic currents and subsequent release of hydrogen gas can be related to the hydriding of the Zircaloy tubes. The data enclosed in this report indicate a substantial amount of galvanic action in the downstream dummy section of the process tube. The use of certain metal coatings on the aluminum spacers could reverse the galvanic cell polarity and cause corrosion of the process tube which would not be desirable.