Development of an isotope analysis method based on diode laser absorption spectroscopy using an arc-jet plasma wind tunnel

Radioactive isotopes in nuclear fuel and radioactive waste must be quantified for safety control and management of various nuclear facilities. In this study, an isotope analysis method based on diode laser absorption spectroscopy by using an arc-jet plasma wind tunnel is developed for rapid analysis without sample preparation and sophisticated maintenance. The translational temperature and flow velocity downstream of a supersonic nozzle are measured using an atomic argon transition of 826.45 nm from an excited state, and then, the temperature upstream of the nozzle is estimated using the two measured values. Next, the trace gas measurement capability is verified by injecting natural xenon into argon plasma, and optical measurements are carried out at an atomic xenon transition to 823.16 nm from a metastable state. The detection limit of xenon over the argon molar ratio is estimated to be 140 parts per million downstream.