I. Takagi et al., DEUTERIUM RADIAL REDISTRIBUTION IN ZR-LINER CLADDING TUBES, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 118(1-4), 1996, pp. 238-241
Hydrogen isotopes in fuel cladding of nuclear power reactor are of muc
h interest in relation to the secondary hydriding of claddings, tritiu
m content in spent fuels, and other issues. Using nuclear reaction ana
lysis (NRA), we performed out-of-reactor analysis on the radial distri
bution of deuterium in Zr-liner zircaloy-2 claddings. Three specimens
of the cladding were thermally charged with deuterium gas at 673 K in
advance. One was quenched in water (sample 1) and the others were grad
ually cooled to 433 K (samples 2 and 3). The NRA showed that the radia
l distribution of deuterium was flat from the inside to the outside in
the sample 1 tube. As diffusion of deuterium is much restricted after
quenching, the distribution observed is considered to be the same as
that before quenching. In samples 2 and 3, on the other hand, a sharp
peak was formed in the zirconium liner near the Zr-zircaloy-2 interfac
e. The peak concentration in the liner was several times as large as t
hat in zircaloy-2. This indicated that the migration towards Zr-liner
in the gradual cooling resulted in the redistribution of deuterium. Th
e redistribution can be explained by a slight difference in tbe termin
al solubility of deuterium in the two materials, Zr and zircaloy-2. Th
e large effect of this slight difference on the redistribution of hydr
ogen isotopes is also discussed.