Analysis of Radioactive Waste Supernate by Laser-Raman Spectrometry

A laser-Raman spectrometric method was developed for the determination of polyatomic ions in alkaline high-level radioactive waste super-nates. From peak heights of well-resolved Raman hands, concentrations of NO₂₋, SO₄²⁻, CrO₄²⁻, PO₄³⁻, and Al(OH)₄₋ ions are determined relative to NO₃₋ ion concentrations in raw solutions. The concentration of an NO₃₋ ion is determined independently by quantitative dilution of an aliquot with standardized 2M NaClO₄. The relative precision at the 95% confidence level for a single determination is ±5%. Although Savannah River Plant waste samples are pale yellow and turbid, centrifugation clarifies them sufficiently for reproducible spectra to be recorded with 488-nm Ar⁺ excitation.