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Title: Separating and Stabilizing Phosphate from High-Level Radioactive Waste: Process Development and Spectroscopic Monitoring

Removing phosphate from alkaline high-level waste sludges at the Department of Energy's Hanford Site in Washington State is necessary to increase the waste loading in the borosilicate glass waste form that will be used to immobilize the highly radioactive fraction of these wastes. We are developing a process which first leaches phosphate from the high-level waste solids with aqueous sodium hydroxide, and then isolates the phosphate by precipitation with calcium oxide. Tests with actual tank waste confirmed that this process is an effective method of phosphate removal from the sludge and offers an additional option for managing the phosphorus in the Hanford tank waste solids. The presence of vibrationally active species, such as nitrate and phosphate ions, in the tank waste processing streams makes the phosphate removal process an ideal candidate for monitoring by Raman or infrared spectroscopic means. As a proof-of-principle demonstration, Raman and Fourier transform infrared (FTIR) spectra were acquired for all phases during a test of the process with actual tank waste. Quantitative determination of phosphate, nitrate, and sulfate in the liquid phases was achieved by Raman spectroscopy, demonstrating the applicability of Raman spectroscopy for the monitoring of these species in the tank waste process streams.
Authors:
; ; ; ;
Publication Date:
OSTI Identifier:
1047383
Report Number(s):
PNNL-SA-85510
Journal ID: ISSN 0013-936X; ESTHAG; EY7144147; TRN: US1203939
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Science and Technology; Journal Volume: 46; Journal Issue: 11
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BOROSILICATE GLASS; CALCIUM OXIDES; HIGH-LEVEL RADIOACTIVE WASTES; IONS; LIQUIDS; LOADING; MONITORING; NITRATES; PHOSPHATES; PHOSPHORUS; PRECIPITATION; RAMAN SPECTROSCOPY; REMOVAL; SLUDGES; SODIUM HYDROXIDES; SOLIDS; SPECTRA; STREAMS; SULFATES; TANKS; WASHINGTON; WASTE FORMS; WASTE PROCESSING; WASTES High-level waste; phosphate separation; phosphate removal; Raman; infrared; spectroscopy; on-line monitoring