Feasibility of Uranium Concentration Measurements for H Canyon Tank 16.7

SRTC evaluated the feasibility of using the H Canyon on-line diode array spectrophotometer to measure uranium concentrations in Tank 16.7. On-line measurements will allow an increase in highly enriched uranium (HEU) production by removing delays associated with off-line measurements. The instrument must be able to measure uranium at concentrations below 1.0 g/L with an uncertainty no greater than 0.3 g/L. SRTC determined that the system has a limit of quantitation of 0.15 g/L. At concentrations of 0.5 and 1.0 g/L, the spectrometer uncertainty is 0.10 g/L. No design changes, such as an increase in flow cell pathlength, are required to obtain this performance. Expected levels of iron in Tank 16.7 solutions will not interfere with the measurement. The CHEMCHEK method should not be used for confirmatory analysis, as it contributes excessively to the overall uncertainty of the measurement. SRTC expects that the spectrophotometer will meet the measurement requirements for Tank 16.7. WSRC-TR-2002-00568 v TABLE OF CONTENTS ABSTRACT...................................................................................................................... iv TABLE OF CONTENTS.................................................................................................. v LIST OF FIGURES ......................................................................................................... vi LIST OF TABLES ........................................................................................................... vi 1. SUMMARY................................................................................................................... 1 2. INTRODUCTION......................................................................................................... 1 2.1 Scope ................................................................................................................... 1 2.2 Spectrophotometer............................................................................................ 1 2.3 Study ................................................................................................................... 3 3. EXPERIMENTAL METHODS................................................................................... 3 3.1 Uranium prediction models .............................................................................. 3 3.2 Test spectra ........................................................................................................ 5 4. RESULTS ................................................................................................................. 5 5. DISCUSSION........................................................................................................... 8 6. CONCLUSIONS...................................................................................................... 9 7. ACKNOWLDGEMENTS..................................................................................... 10 8. REFERENCES........................................................................................................... 10 WSRC-TR-2002-00568 vi LIST OF FIGURES Figure 1. Schematic diagram of spectrophotometer system. ........................................2 Figure 2. Spectra of low uranium solutions....................................................................6 Figure 3. Spectra of iron-bearing solutions....................................................................7 Figure 4. Spectra of low uranium solutions in H Canyon. ............................................8 Figure 5. Uranium model uncertainty as a function of concentration. ......................10 LIST OF TABLES Table 1. SRTC and H Canyon uranium prediction models..........................................5 Table 2. Prediction of low uranium solutions.................................................................6 Table 3. Measurements of low uranium calibration solutions in H Canyon. ..............8 Table 4. Estimated spectrometer uncertainties............................................................10 WSRC-TR-2002-00568 1