Radiation damage of fluorocarbon by krypton-85 beta-rays, (1)

Irradiation experiments using 60Co γ-rays were undertaken on CCl3F to examine the radiation damage of fluorocarbon, used as solvent in the recovery of 85Kr from the off-gas of fuel reprocessing plants operating on the solvent absorption. The conditions of irradiation were varied in the range of 2.3 x 104 -- 1.1 x 106 rad/h in terms of dose rate and -30 -- 160C in temperature, to assemble information on the kinds of degradation products generated, the relationship between decomposition rate and absorbed dose, and the effects on the decomposition exerted by certain factors (dose rate, temperature, impurities, wall materials). The results obtained included the following findings: (1) The degradation products of CCl3F comprised halogen ions and thirteen kinds of fluorocarbons. (2) The rate of decomposition of CCl3F and the yield of the individual degradation products were roughly proportional to the absorbed dose; the energy decomposition of CCl3F at -300C was 0.013 mol/0/Mrad (G = 1.4) under a dose rate of 1.1 x 106 rad/h. (3) The decomposition rate of CCl3F was inhibited by increasing dose rate, and promoted by rising irradiation temperature. (4) The yields of halogen ions and C2Cl4F2, and the decomposition rate of CCl3F increased with the addition of air. (5) No appreciable influence on the decomposition of CCl3F was observed to be exercised by the presence of such materials as stainless steel, Cu and Al. (author)