CORROSION OF ZIRCALOY IN CREVICES UNDER NUCLEATE BOILING CONDITIONS

摘要

The MSAR corrosion test loop was used to study the effect of VEE-shaped crevices on the corrosion resistance of Zircaloy under boiling heat-transfer conditions in both ammoniated and litigated water at pH 10.5. Zircaloy-2 and Zircaloy-4 were compared under identical geometric, thermal, and hydraulic conditions. An effort was made to study the effect of iron oxide crud deposits on crevices of slightly variant geometry.nThe tests were run at 586 to 587F (Tsat for a pressure of 1390 to 1400 psig). Water velocity was held in the range of 1 to 3 fps. Control was such that the onset of nucleate boiling should, on the average, have taken place at about the middle of the 5-in.-long, thin-walled crevice specimens. Specimens were vertically oriented in an effort to mock up the most common orientation of flow channels in nuclear reactor cores. Heating of specimens was resistive with 60-cycle a-c, at a heat flux of 500,000 Btu/ft2-hr.