Sensitivity and uncertainty analyses applied to one-dimensional radionuclide transport in a layered fractured rock: MULTFRAC --Analytic solutions and local sensitivities; Phase 2, Iterative performance assessment: Volume 1

Technical Report · Tue Dec 01 04:00:00 EST 1992

DOI:https://doi.org/10.2172/138734· OSTI ID:138734

Gureghian, A B; Wu, Y T; Sagar, B ^[1]; Codell, R A ^[2]

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1. Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses
2. Nuclear Regulatory Commission, Washington, DC (United States)

Exact analytical solutions based on the Laplace transforms are derived for describing the one-dimensional space-time-dependent, advective transport of a decaying species in a layered, saturated rock system intersected by a planar fracture of varying aperture. These solutions, which account for advection in fracture, molecular diffusion into the rock matrix, adsorption in both fracture and matrix, and radioactive decay, predict the concentrations in both fracture and rock matrix and the cumulative mass in the fracture. The solute migration domain in both fracture and rock is assumed to be semi-infinite with non-zero initial conditions. The concentration of each nuclide at the source is allowed to decay either continuously or according to some periodical fluctuations where both are subjected to either a step or band release mode. Two numerical examples related to the transport of Np-237 and Cm-245 in a five-layered system of fractured rock were used to verify these solutions with several well established evaluation methods of Laplace inversion integrals in the real and complex domain. In addition, with respect to the model parameters, a comparison of the analytically derived local sensitivities for the concentration and cumulative mass of Np-237 in the fracture with the ones obtained through a finite-difference method of approximation is also reported.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Div. of High-Level Waste Management; Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses
• Sponsoring Organization: Nuclear Regulatory Commission, Washington, DC (United States)
• OSTI ID: 138734
• Report Number(s): NUREG/CR--5917-Vol.1; CNWRA--91-010-Vol.1; ON: TI93008169
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
54 ENVIRONMENTAL SCIENCES
99 GENERAL AND MISCELLANEOUS
APERTURES
CURIUM 245
DECAY
FLUID FLOW
GEOLOGIC FRACTURES
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
LAPLACE TRANSFORMATION
MATHEMATICAL MODELS
NEPTUNIUM 237
RADIONUCLIDE MIGRATION
ROCKS
TUFF
UNDERGROUND DISPOSAL
Yucca Mountain Project