Steam Bath Cycle Required for Isotopic Homogeneity of 14-Ton UF₆ Cylinder

It is concluded from data contained herein that 12 hours in a steam bath at 200 ± 5°F is adequate to ensure isotopic homogeneity for a l4~ton UF₆ cylinder moved from the yard in winter months. The requirement is that the steam bath surrounding the cylinder be maintained at 200°F for 12 consecutive hours prior to sampling. Total bath time necessary is variable, depending on steam line capacity, and beginning temperature of cylinder which at the outset acts as a heat sink. Thus, assay homogeneity may be assured by bringing bath temperature up to 200°F and maintaining it at that level 12 hours before sampling. This procedure applies when the U²³⁵ assay range of UF6 drained into the 14-ton cylinder does not exceed 20 percent of the average cylinder assay. This procedure is applicable to UF₆ cylinder Model 48F (l), and is shown to be conservative for use in providing isotopic homogeneity to Model 30A (2-1/2 ton) or 48A (10 ton). The procedure may also be used for any cylinder with a diameter ≤ 4 ft. and a length ≤12 ft. (author)