A visible/near-ir spectral database for plutonium solutions of known nitric acid, fluoride, and oxalate composition

Abstract

Fluoride and oxalate are common components of plutonium process solutions. Unfortunately, these anions form highly stable complexes that interfere in many plutonium process operations. Knowledge of the fluoride and oxalate content of process solutions may allow appropriate corrective action to be taken to prevent such interference. On-line spectrophotometry, which is being developed t o monitor process solutions at the Los Alamos Plutonium Facility, has the potential t o detect and estimate the concentration of these two anions and other solution constituents when the spectral data are processed using chemometric techniques. Spectra of 126 solutions that contained known concentrations of plutonium, fluoride, oxalate, and nitric acid were acquired as a database for on-line spectrophotometry. These spectra and a discussion of their unique spectral features are presented.

FY-2010 Process Monitoring Technology Final Report

“…Prominent features of this series of spectra are the absorption bands associated with Pu(IV) (observed 648-662, 707, 790, 860, and 1075 nm) [15,18,[42][43][44] and Pu(VI) (observed 625, 817, 831, 857, 948, 983, and 1160 nm) [44][45][46]. The absorbance bands associated with Pu(IV) are attributed to Pu(NO 3 ) n 4-n nitrato complexes determined to be dominant below 5 M nitric acid [15,46,47].…”