The UO
2+2 fluorescence spectra were measured for solutions simulating the raffinate of the codecontamination process in nuclear fuel reprocessing plants, including 27 kinds of coexisting ionic species. When the coexisting ion concentration was equal to that of the raffinate, the U concentration was determined in the range of 2100 mg/dm
3 and detection sensitivity was only 1/6 that in the reference solution containing no coexisting ions. The UO
2+2 fluorescence intensity decreased with increasing coexisting ion concentrations for the following three reasons.
The first was absorption of the excitation beam by these ions. The second was absorption of fluorescence by these ions. The last was fluorescence quenching by interactions between UO
2+2 and the coexisting ions. The respective ratios of fluorescence reduction attributed to these reasons at the raffinate were estimated as 0.26, 0.87 and 0.59, based on comparison of experimental results with calculations for absorption of the excitation beam and fluorescence.
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