Determination of Tantalum Mass Transfer in Pu-Co-Ce Liquid Metals by Gamma Scanning

The mass transfer of tantalum in Pu-Co-Ce melts was studied by gamma-scanning capsules containing radioactive tantalum in contact with the liquid metal. Eight experiments were run with melts of 5- and 8-g Pu/cm³ at temperatures from 700 to 750°C at the hot zones and with 25°C/in. of longitudinal temperature gradient. The results show all mass transfer rates in tantalum capsules to be < 1 mil/year and, in most cases, < 0.2 mil/year when the source and sink are not closely coupled. A carbon addition to the system appeared to be deleterious since, in one experiment with all capsule surfaces carburized, rates were accelerated by a factor of 10.