Helium release from metal tritides

Technical Report · Thu Jul 01 04:00:00 EDT 1976

OSTI ID:7356905

Kass, W J

Comparisons of the erbium tritide powder samples indicates a strong dependence of /sup 3/He release on the original tritium stoichiometry. The dependence cannot be explained using only a percolation model in which the /sup 3/He/Er ratio is the only significant independent variable since this model does not predict a tritium stoichiometry dependence. Consequently, since all the samples are of the same structure in this stoichiometry range, it appears that the subsequent filling of more and more octahedral interstices in the erbium lattice by tritium contributes to the differences in release rates. The release data for the scandium tritium solid solution samples appears to be governed by the difference in grain sizes among the samples. This conclusion is consistent with a release model in which the release rate is strictly dependent on the amount of /sup 3/He near a grain boundary. Once /sup 3/He reaches a grain boundary, an easy pathway along this boundary allows complete release from the solid. The comparison of the data from the Er, Zr, Ti, and Sc films indicates that accelerated release occurs at different /sup 3/He/M ratios. Simple percolation theory would predict accelerated release to occur for all these samples at the same /sup 3/He/M ratio. The value of this ratio depends only on the sublattice structure of the tritium in the metal tritide (assuming the generated /sup 3/He initially remains in the same site which holds the tritium). This value is between 0.24 and 0.30 for a site percolation probability greater than 0.8. It appears, therefore, that a model which includes interatomic potentials of the host lattice including the effect of defects such as vacancies is necessary to explain these variations in release rates.

• Research Organization: Sandia Labs., Albuquerque, N.Mex. (USA)
• DOE Contract Number: AT(29-1)-789
• OSTI ID: 7356905
• Report Number(s): SAND-76-0339
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
CRYOGENIC FLUIDS
DECAY
DEGASSING
ELEMENTS
ERBIUM COMPOUNDS
ERBIUM HYDRIDES
FLUIDS
HELIUM
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN TRITIDE
LABELLED COMPOUNDS
MEASURING METHODS
NONMETALS
POWDERS
RARE EARTH COMPOUNDS
RARE GASES
REMOVAL
SCANDIUM COMPOUNDS
SCANDIUM HYDRIDES
TITANIUM COMPOUNDS
TITANIUM HYDRIDES
TRANSITION ELEMENT COMPOUNDS
TRITIUM COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM HYDRIDES