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Hydrothermal interactions between calcine, glass, spent fuel, and ceramic-waste forms with representative shale-repository rocks

Technical Report ·
OSTI ID:6749070
; ; ; ; ;
A prototype waste glass (PNL 76-68), a prototype ceramic (SPC-2), a raw PW-7a calcine, and a simulated spent fuel were reacted individually with six shales in the presence of water in sealed gold capsules. Conditions were (usually) 1:1:1 waste:shale:water by weight, P = 30 MPa, T = 100, 200, 300 and 400/sup 0/C. Reaction products were characterized by optical microscopic and SEM examination, EDX analysis, x-ray diffraction analysis, and Gandolfi X-ray analysis. The shales react with the waste forms presumably by dissolution in water followed by reaction between the solution and the shale minerals. Degree of reaction ranges from barely detectable at 100/sup 0/C to almost complete alteration of the waste forms and shales at 400/sup 0/C. Cesium extracted from the waste forms reacts with alumino-silicate minerals to form a pollucite-analcime solid solution at lower temperatures. It is shown that the observed gradual disappearance of pollucite in higher temperature runs can be explained by the decomposition of the pollucite-analcime solid solution into a cesium-rich pollucite plus feldspar. The seeming disappearance of pollucite from high temperature runs need not imply loss of cesium fixation. The uranium reacts with silicate minerals under oxidizing conditions to form alkali uranyl silicates (of which weeksite is the most common example). Shales containing sulfide minerals or organic materials maintain a reducing environment which keeps uranium (and presumably transuranic elements) in the far less soluble tetravalent state. Powellite, CaMoO/sub 4/, appears frequently as the reaction product of molybdenum. 23 figures, 15 tables.
Research Organization:
Pennsylvania State Univ., University Park (USA). Materials Research Lab.
DOE Contract Number:
AC06-76RL01830
OSTI ID:
6749070
Report Number(s):
ONWI-306; ON: DE83002640
Country of Publication:
United States
Language:
English

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Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
053000 -- Nuclear Fuels-- Environmental Aspects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CALCINED WASTES
CERAMICS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIFFRACTION
ELECTRON DIFFRACTION
ELECTRON MICROSCOPY
ENERGY SOURCES
FUELS
GLASS
HIGH TEMPERATURE
HYDROTHERMAL ALTERATION
MANAGEMENT
MATERIALS
MICROSCOPY
MICROSTRUCTURE
MINERALS
NUCLEAR FUELS
OPTICAL MICROSCOPY
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE STORAGE
RADIOACTIVE WASTES
REACTOR MATERIALS
ROCKS
SCANNING ELECTRON MICROSCOPY
SCATTERING
SEDIMENTARY ROCKS
SHALES
SPENT FUELS
STORAGE
TEMPERATURE DEPENDENCE
UNDERGROUND STORAGE
WASTE MANAGEMENT
WASTE STORAGE
WASTE-ROCK INTERACTIONS
WASTES
X-RAY DIFFRACTION