Thermodynamic coupling of heat and matter flows in near-field regions of nuclear waste repositories

Conference · Tue Nov 01 00:00:00 EST 1983

OSTI ID:5491528

Carnahan, C L

In near-field regions of nuclear waste repositories, thermodynamically coupled flows of heat and matter can occur in addition to the independent flows in the presence of gradients of temperature, hydraulic potential, and composition. The following coupled effects can occur: thermal osmosis, thermal diffusion, chemical osmosis, thermal filtration, diffusion thermal effect, ultrafiltration, and coupled diffusion. Flows of heat and matter associated with these effects can modify the flows predictable from the direct effects, which are expressed by Fourier's law, Darcy's law, and Fick's law. The coupled effects can be treated quantitatively together with the direct effects by the methods of the thermodynamics of irreversible processes. The extent of departure of fully coupled flows from predictions based only on consideration of direct effects depends on the strengths of the gradients driving flows, and may be significant at early times in backfills and in near-field geologic environments of repositories. Approximate calculations using data from the literature and reasonable assumptions of repository conditions indicate that thermal-osmotic and chemical-osmotic flows of water in semipermeable backfills may exceed Darcian flows by two to three orders of magnitude, while flows of solutes may be reduced greatly by ultrafiltration and chemical osmosis, relative to the flows predicted by advection and diffusion alone. In permeable materials, thermal diffusion may contribute to solute flows to a smaller, but still significant, extent.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5491528
• Report Number(s): LBL-16732; CONF-831174-56; ON: DE84004651
• Resource Relation: Conference: Materials Research Society annual meeting, Boston, MA, USA, 14 Nov 1983; Other Information: Portions are illegible in microfiche products
• Country of Publication: United States
• Language: English

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12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
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HEAT FLOW
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FLUID FLOW
RADIOACTIVE WASTE DISPOSAL
SOLUTES
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052002* - Nuclear Fuels- Waste Disposal & Storage