Abstract: A graphite can be easily and completely gasified by soaking the graphite in a catalyst solution of a nitrate of a gasification catalyst selected from the group consisting of cobalt, nickel and iron and nitric acid to impregnate the graphite with the gasification catalyst and then gasifying the thus catalyst-impregnated graphite at temperatures above 1000.degree. C. And further a graphite can be easily and completely gasified by soaking the graphite in a catalyst solution of cobalt nitrate, sodium nitrate and nitric acid to add the mixing catalyst of cobalt and sodium to the graphite uniformly and then gasifying the thus catalyst-added graphite at temperatures below 900.degree. C.

Abstract: An effective method for purifying plutonium hexafluoride for the reprocessing of the spent nuclear fuel or for the recovery of fuel plutonium from the scrap by fluoride-volatility with high decontamination factors is presented using a selective adsorption of the fission products fluorides by letting the gas mixture flow through a layer of an adsorbent consisting of one or more of the specified compounds selected from hexafluoro sodium aluminate, zinc fluoride, nickel fluoride and ferric fluoride at an elevated temperature. The principle of the purification method is based on the fact that the fluorides of the fission products are easily adsorbed by the adsorbent but little plutonium hexafluoride is adsorbed. The fluorides of the fission products are easily removed from the adsorbent by heating and the recycling use of the adsorbent is possible.