Application of high enthalpy wind tunnel to isotope ratio measurement by enhancement of wavelength resolution

Kuwahara, Akira   ; Nankawa, Takuya ; Matsui, Makoto*

In this research, we propose a novel laser absorption spectroscopy (LAS) system combined with high enthalpy wind tunnel to measure the isotope ratio of radioactive elements in nuclear fuel and radioactive waste. In detecting the isotope ratio of radioactive elements, spectroscopic technique with high wavelength selectivity would be effective, but no established method is available due to the small differences in energy levels of isotopes. We use the supersonic nozzle in high enthalpy wind tunnel and applied LAS to the downstream flow to enhance the wavelength resolution by decreasing the spectral width attribute to the flow temperature. In this paper, first the measurable range of atomic species was discussed. Next, we demonstrated measurements of the isotope ratio by using xenon gas. As a result, isotope shifts of xenon atoms were detected and the spectral width was evaluated for a variation of the gas temperature.