THERMOTRANSPORT OF HYDROGEN IN ZIRCALOY-4 AND MODIFIED ZIRCALOY-4

Thermotransport of hydrogen, the flux of hydrogen due to an applied te mperature gradient, was investigated in Zircaloy-4 and modified Zircal oy-4 alloys. The modified Zircaloy-4 was prepared by changing the chem ical compositions of Zircaloy-4. The heat of transport (Q) for hydrog en was determined to evaluate the magnitude and direction of thermotra nsport in the alloys, and the hydrogen distribution induced by thermot ransport was investigated. During the thermotransport hydrogen existed in two different regions, the single-phase region and the two-phase r egion. At the interface between the two different regions, the hydroge n concentration distribution did not show a sharp discontinuity but a relatively smooth curve. The values for Q in Zircaloy-4 and modified Zircaloy-4 alloys were considered to be about 30 kJ/mol. (C) 1998 Else vier Science B.V. All rights reserved.