Organic Telluride Formation during a Severe Nuclear Accident (ORTEF)
Anna-Elina Pasi, Fredrik Börjesson Sandén, Teemu Kärkelä, Christian Ekberg,
The potential formation of organic species during a severe nuclear reactor accident is a cause of concern due to the very high volatility of organic compounds. The interactions between organic material and fission products are especially concerning since this could lead to an increased source term in post-accident conditions. One of the fission products potentially forming volatile organic species is tellurium. Although evidence of the formation of organic tellurides in accident conditions was only showed recently, this raises concerns whether organic tellurium species should be considered a significant threat in accident scenarios. The aim of the ORTEF project was to investigate potential interactions between tellurium and organic material in the gas phase. The experimental conditions in ORTEF were chosen to represent those likely present in the containment gas phase where tellurium aerosols would be present simultaneously with volatile organics. The results show that the presence of organics increases the transport of tellurium in the gas phase. This was observed by measuring higher concentration of tellurium in the trap solution in the presence of organics compared to the reference conditions in both reducing and inert conditons. Oxidizing atmosphere and the consequent oxidation of elemental tellurium to tellurium oxide inhibited the interactions. Although the speciation analysis was inconclusive, the significant increase in the gaseous fraction is a clear indication of interactions. Whether the increased transport is due to the formation of organic tellurides or other interactions remains for further studies.
severe accident, source term, fission product, tellurium