Nerva Fuel Element Development Program Summary Report - July 1966 through June 1972 Impregnation Studies

Two methods were employed to densify graphite bodies: gaseous impregnation and liquid impregnation. Gaseous impregnation consisted of two processes: direct flow and pulse vacuum. Liquid impregnation was based on the use of a polymer of cinnamylideneindene. Both types of gaseous impregnation processes were successful in densifying the fuel element graphites; however, the process time of the pulse-vacuum method was shown to be significantly shorter than that of the direct-flow process. The liquid impregnation process was also successful. Two to four impregnation cycles were required to obtain a maximum density