skip to main content

Title: Modeling of Boehmite Leaching from Actual Hanford High-Level Waste Samples

The Department of Energy plans to vitrify approximately 60,000 metric tons of high level waste sludge from underground storage tanks at the Hanford Nuclear Reservation. To reduce the volume of high level waste requiring treatment, a goal has been set to remove about 90 percent of the aluminum, which comprises nearly 70 percent of the sludge. Aluminum in the form of gibbsite and sodium aluminate can be easily dissolved by washing the waste stream with caustic, but boehmite, which comprises nearly half of the total aluminum, is more resistant to caustic dissolution and requires higher treatment temperatures and hydroxide concentrations. In this work, the dissolution kinetics of aluminum species during caustic leaching of actual Hanford high level waste samples is examined. The experimental results are used to develop a shrinking core model that provides a basis for prediction of dissolution dynamics from known process temperature and hydroxide concentration. This model is further developed to include the effects of particle size polydispersity, which is found to strongly influence the rate of dissolution.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
910261
Report Number(s):
PNNL-SA-51903
Journal ID: ISSN 0149-6395; SSTEDS; TRN: US0704045
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Separation Science and Technology, 42(8):1719-1730; Journal Volume: 42; Journal Issue: 8
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; HIGH-LEVEL RADIOACTIVE WASTES; LEACHING; HANFORD RESERVATION; SLUDGES; ALUMINIUM OXIDES; ALUMINIUM HYDROXIDES; DISSOLUTION; CHEMICAL REACTION KINETICS; MATHEMATICAL MODELS; RADIOACTIVE WASTE PROCESSING Boehmite, Dissolution, High Level Waste