Hostname: page-component-586b7cd67f-r5fsc Total loading time: 0 Render date: 2024-11-25T17:38:09.405Z Has data issue: false hasContentIssue false
  • English
  • Français

Slag-Based Saltstone Formulations

Published online by Cambridge University Press:  28 February 2011

C. A. Langton
C. A. Langton*
Affiliation:
E. I. du Pont de Nemours and CompanySavannah River LaboratoryAiken, SC 29808
Get access

Abstract

Approximately 400 × 106 liters of low-level alkaline salt solution will be treated at the Savannah River Plant (SRP) Defense Waste Processing Facility (DWPF) prior to disposal in concrete vaults at SRP. Treatment involves removal of Ca+and Sr+2 followed by solidification and stabilization of potential contaminants in saltstone, a hydrated ceramic waste form.

Chromium, technetium, and nitrate releases from saltstone can be significantly reduced by substituting hydraulic blast furnace slag for portland cement in the formulation designs. Slag-based mixes are also compatible with Class F fly ash used in saltstone as a functional extender to control heat of hydration and reduce permeability. (Class F fly ash is locally available at SRP.)

A monolithic waste form is produced by the hydration of the slag and fly ash. Soluble ion release (NO3−) is controlled by the saltstone microstructure (bulk porosity and pore size and connectivity). Chromium and technetium are 103−104 times less leachable from slag mixes than from cement-based waste forms. Results suggest that chemical stabilization rather than physical entrapment, as in the case of nitrate is responsible for this improved leaching. Reduction of Cr+6 and Tc+7 to Cr+3 and Tc+4 by ferrous iron or Mn+2 in the slag and subsequent precipitation of the relatively insoluble phses Cr(OH)3 and TcO2 are proposed as the stabilizing reactions.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 112: Symposium P – Scientific Basis for Nuclear Waste Management XI , 1987 , 61
Copyright
Copyright © Materials Research Society 1988

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Federal Register, Vol.45, No. 98, p. 33121 (Monday, May 19, 1980).Google Scholar
2. Wilhite, E. L., “Waste Disposal at the Savannah River Plant,” presented at the ANS International Meeting: Low-, Intermediate-, and High-Level Waste Management and Decontamination and Decommissioning, Niagara Falls, NY (September 14–18, 1986).Google Scholar
3. Pepper, D. W., “Transport of Nitrate from a Large, Cement-Based Waste Form,” presented at the Sixth International Conference of Finite Elements in Water Resources, Lisbon, Portugal (June 1–5, 1986).Google Scholar
4. Langton, C. A., Oblath, S. B., Pepper, D. W., and Wilhite, E. L., “Waste Salt Disposal at the Savannah River Plant,” presented at the Summer National Meeting of the AIChE, Boston, MA (August 24–27, 1986).Google Scholar
5. Wilhite, E. L., “Concept Development for Saltstone and Low-Level Waste Disposal,” presented at Waste Management '87, Tucson, AZ (March 1–5, 1987).Google Scholar
6. Wilhite, E. L., Savannah River Laboratory, Aiken, SC, Personal Communication (July 1987).Google Scholar
7. Langton, C. A., Dukes, M. D., and Simmons, R. V., “Cement-Based Waste Forms for Disposal of Savannah River Plant Low-Level Radioactive Salt Waste, Materials Research Society Annual Meeting, Boston, MA (November 14–17, 1983).Google Scholar
8. Langton, C. A., unpublished data (1987).Google Scholar
9. ANSI/ANS-16.1–1986, “Measurement of the Leachability of Solidified Low-Level Radioactive Wastes by a Short-Term Test Procedure, An American National Standard, American Nuclear Society, La Grange Park, IL (April 14, 1986).Google Scholar