DIMENSIONAL INSTABILITY OF URANIUM--III. Third Annual Progress Report for June 30, 1957 to June 30, 1958

The mechanism of dimensional instability of uramium is under investigation. Ih order to confirm an assumption of the diffusion theory, the magnitude of diffusion anisatropy in alpha-uranium single crystuls is being determincd by measurement of the self-diffusion coefficients along principal crystullographic directions. lnitial measurements have yielded values of 5 x 10/ sup -15/ cm/sup 2//sec along the (010! and 4 x 10/sup -15/ cm/sup 2/ sec along the (OOl!. These values are being rechecked. in addition, in- -pile experiments designed to further clarify the effect of grain size on growth under irradiation have been initiated. (For preceding period see SEP-246.) (auth