文摘
In the uranium enrichment plants of the South African Nuclear Energy Corporation, (Necsa), sintered polytetrafluoroethylene (PTFE) filters were used to remove gas entrained solid particles. The filters contained enriched uranium fluoride and uranium oxy-fluoride compounds Initial attempts, directly after removal from the enrichment plants, to decontaminate these filters using various aqueous solutions, were unsuccessful however recent attempts to leach the absorbed enriched uranium were successful. This resulted in a study to determine the effect of mainly α-irradiation from the enriched uranium on the morphology of PTFE. A Monte Carlo N-Particle transport code (MCNP), a general purpose radiation transport code modelling the interaction of radiation with materials that simulate nuclear processes, was used to determine the rate of PTFE radiolysis. To confirm the modelling data, analytical techniques were used to study the morphology changes in the PTFE structure. Results indicated that the crystallinity increased while the molecular weight of the PTFE decreased which could be attributed to the radiation induced degradation of the PTFE by the absorbed enriched uranium.
