Feasibility of fourier transform (FT) infrared spectroscopy for monitoring heavy water concentration in pressurized heavy water reactor

摘要

The feasibility of Fourier Transform Infrared (FT-IR) spectroscopy for the measurement of D_2O (heavy water) concentration in a pressurized heavy water reactor has been studied. FT-IR spectroscopy has been proved to ben an excellent analytical technique to quickly and non-invasively determine a D_2O concentration in H_2O without using any chemical reagents. The stretching band of D_2O (2700-2400 cm~(-1)) has been investigated for its quantitative analysis. Fortunately, this band was located in between two strong infrared absorption bands of H_2O. Therefore, the attenuation of IR radiation in this region, caused by the strong absorption of H_2O, was greatly reduced and this made it possible to observe the characteristic band of D_2O with minimal H_2O interference. The cell pathlength was of great concern since it was closely related to the signal-to-noise ratio of the absorption band of D_2O. The optimal pathlength of 0.2 mm was chosen to provide a reasonable analytical sensitivity as well as to keep noise as minimum. Both the integrated area (under 2650-2400 cm~(-1) band) and partial least squares (PLS) regression methods were used to build calibration models, and the results were compared with each other. The PLS regression provided the better calibration performance with the standard error of prediction (SEP) of 3.2 ppm in the 100-250 ppm D_2O range.