Solidification of low-level radioactive wastes in masonry cement. [Masonry cement-boric acid waste forms]
Portland cements are widely used as solidification agents for low-level radioactive wastes. However, it is known that boric acid wastes, as generated at pressurized water reactors (PWR's) are difficult to solidify using ordinary portland cements. Waste containing as little as 5 wt % boric acid inhibits the curing of the cement. For this purpose, the suitability of masonry cement was investigated. Masonry cement, in the US consists of 50 wt % slaked lime (CaOH/sub 2/) and 50 wt % of portland type I cement. Addition of boric acid in molar concentrations equal to or less than the molar concentration of the alkali in the cement eliminates any inhibiting effects. Accordingly, 15 wt % boric acid can be satisfactorily incorporated into masonry cement. The suitability of masonry cement for the solidification of sodium sulfate wastes produced at boiling water reactors (BWR's) was also investigated. It was observed that although sodium sulfate - masonry cement waste forms containing as much as 40 wt % Na/sub 2/SO/sub 4/ can be prepared, waste forms with more than 7 wt % sodium sulfate undergo catastrophic failure when exposed to an aqueous environment. It was determined by x-ray diffraction that in the presence of water, the sulfate reacts with hydrated calcium aluminate to form calcium aluminum sulfate hydrate (ettringite). This reaction involves a volume increase resulting in failure of the waste form. Formulation data were identified to maximize volumetric efficiency for the solidification of boric acid and sodium sulfate wastes. Measurement of some of the waste form properties relevant to evaluating the potential for the release of radionuclides to the environment included leachability, compression strengths and chemical interactions between the waste components and masonry cement. 15 refs., 19 figs., 9 tabs.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6338376
- Report Number(s):
- BNL-52074; ON: DE87012305
- Resource Relation:
- Other Information: Portions of this document are illegible in microfiche products. Original copy available until stock is exhausted
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
BORIC ACID
PHASE DIAGRAMS
BORON
LEACHING
CEMENTS
COMPARATIVE EVALUATIONS
COMPRESSION STRENGTH
CESIUM 137
COBALT 60
LOW-LEVEL RADIOACTIVE WASTES
CHEMICAL COMPOSITION
RADIOACTIVE WASTE PROCESSING
SOLIDIFICATION
SODIUM SULFATES
STRONTIUM 85
WASTE FORMS
X-RAY DIFFRACTION
WATER
BWR TYPE REACTORS
EXPERIMENTAL DATA
PWR TYPE REACTORS
TIME DEPENDENCE
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BUILDING MATERIALS
CESIUM ISOTOPES
COBALT ISOTOPES
COHERENT SCATTERING
DATA
DAYS LIVING RADIOISOTOPES
DIAGRAMS
DIFFRACTION
DISSOLUTION
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
EVEN-ODD NUCLEI
HOURS LIVING RADIOISOTOPES
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MANAGEMENT
MATERIALS
MECHANICAL PROPERTIES
MINUTES LIVING RADIOISOTOPES
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PROCESSING
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
RADIOISOTOPES
REACTORS
SCATTERING
SEMIMETALS
SEPARATION PROCESSES
SODIUM COMPOUNDS
STRONTIUM ISOTOPES
SULFATES
SULFUR COMPOUNDS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
WATER COOLED REACTORS
WATER MODERATED REACTORS
YEARS LIVING RADIOISOTOPES
052001* - Nuclear Fuels- Waste Processing
360603 - Materials- Properties
360604 - Materials- Corrosion
Erosion
& Degradation