Radionuclide transport through natural rock fractures
- Los Alamos National Lab., NM (United States); and others
Natural fractures in the subsurface may act as fast pathways for the release of radionuclides to the environment. This hypothesis was tested using natural rock fractures lined with stellerite, magnetite, hollandite, and romanechite from Yucca Mountain, Nevada, the site for a potential high-level nuclear waste repository. Fractured Cores were saturated and a flow of groundwater was initiated Various radionuclides tracers were then injected (H-3, Tc-95m, Np-237). The fracture elutions were then collected as a function of time and analyzed for the percentage of radionuclide tracer recovered. Initial findings indicate the following: (1) it appears that diffusion from the fracture into the matrix can take place even at relatively fast flow rates. (2) Np can be significantly retarded, even during a fracture-flow scenario. Neptunium retardation in fractures could be due to both diffusion into the matrix and sorption onto the minerals lining the fracture walls; and (3) Contrary to previous assumptions about the role of fractures in radionuclide retardation, preliminary results from this experiment indicate that fracture flow does not necessarily result in a fast pathway for actinide migration through fractures.
- OSTI ID:
- 370461
- Report Number(s):
- CONF-960376--
- Country of Publication:
- United States
- Language:
- English
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