Gamma-ray induced degradation of PCBs and pesticides using spent reactor fuel

Gamma-ray induced degradation of several chlorinated hydrocarbons was studied to identify candidate hazardous waste treatment processes. Spent nuclear fuel was used to irradiate PCBs and the pesticides DDT and lindane. Changes produced in these compounds due to ionizing radiation exposure are reported. The applied gamma doses varied from 10 to 100 kGy with an average energy of ca 700 keV. Following irradiation, the samples were analyzed by gas chromatography/mass spectrometry (GC/MS) to determine the extent of decomposition and the nature of the decomposition products. Doses of 100 kGy reduced PCBs to 15% of their initial concentration while DDT and lindane were reduced to below their GC/MS detection limits by doses of 50 kGy. The decomposition products detected were the next less chlorinated species resulting from a simple dechlorination reaction. Mass balance analysis shows however that the dechlorination reaction is not predominant at these gamma-ray doses. Dechlorination products account for only a small percentage of the original analyte concentrations at 100 kGy. The remaining analyte has apparently been decomposed to compounds not detectable by the GC/MS method used; that is, to volatile organics lighter than phenol.