Development of analytical technique for neptunium in the PUREX process by photoacoustic spectroscopy

The analytical technique based on photoacoustic spectroscopy (PAS) was studied for Np(V) in 3N nitric acid. The calibration curve obtained showed good linearity in the concentration range from 10-5 to 1-6M of Np(V). The detection limit concentration and the detection limit absorptivity were found to be 0.014mg/l (5.9 x 10-8M) and 1.15 x 10-6 cm-1, respectively. Wavelength of 616.7 nm was selected for the present study by taking account of the absorption of water. However, the absorption in near infrared range is useful because the biggest absorptions of Np(V) and Np(VI) are at 979.8nm and at 1224nm, respectively. If the influence of water can be eliminated in near infrared range, the concentration lower than 10-9M of Np(V) may become detectable. (author)