Chemical reactions in the helium impurities loop

The Helium Impurities Loop (HIL) at Brookhaven National Laboratory has been run to study reactions between the three metals and the four major helium impurities in the primary circuit of an HTGR. Interest was focused on alternate oxidation and reduction and on carburization of the metals. Preliminary work on hydrogen diffusion through the loop walls and on hydrogen retention in the walls is also presented. During the past year much experience has been accumulated on loop operation and instrument reliability. A small ''bench test'' loop has been built and operated to study reactions under more controlled conditions than possible in the HIL. These efforts are in preparation for more quantitative experiments that will be performed during the coming year. (author)