Reliability evaluation of simulation models for nearfield groundwater flow and radionuclide transport computation

*; *; *; *

JNC TJ8400 2000-005, 71 Pages, 2000/05

JNC-TJ8400-2000-005.pdf:4.0MB

In this research, simulations with some parameters which characterize ground water flow and the reliability evaluation for the expansion of the calculation method of groundwater flow were carried out by using the radionuclide transport computations in nearfield heterogeneous porous media. Concretely contents are follows: (1)With the series of calculation method for three-dimensional saturated/unsaturated groundwater flow and one-dimensional radionuclide transport, the computational analyses with the parameters used in JNC report in 2000 was carried out and the influence of the different input flux was evaluated. (2)The examination of the application for the different ways of inverse laplace transformation which is used in one-dimensional radionuclide transport analysis code "MATRICS" was carried out. (3)The examination of the application of multi-element "MATRICS" (m-MATRICS) for radionuclide transport computations in nearfield heterogeneous porous media was carried out. (4)The series of calculation methods from three-dimensional saturated/unsaturated ground water flow simulation code to one-dimensional radionuclide transport simulation code was integrated.

Compilation of Kinetic Data for Geochemical Calculations

Arthur, R. C,*; Savage, D.*; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu

JNC TN8400 2000-005, 61 Pages, 2000/01

JNC-TN8400-2000-005.pdf:2.83MB

Kinetic data, including rate constants, reaction orders and activation energies, are compiled for 34 hydrolysis reactions involving feldspars, sheet silicates, zeolites, oxides, pyroxenes and amphiboles, and for similar reactions involving calcite and pyrite. The data are compatible with a rate law consistent with surface reaction control and transition-state theoly, which is incorporated in the geochemieal software package EQ3/6 and GWB. Kinetic data for the reactions noted above are strictly compatible with the transition-state rate law only under far-from-equilibrium conditions. It is possiblethat the data are conceptually consistent with this rate law under both far-from-equilibrium and near-to-equilibrium conditions, but this should be confirmed whenever possible through analysis of original experimental results, Due to limitations in the availability of kinetic data for mineral-water reactions, and in order to simplify evaluations of geochemical models of groundwater evolution, it is convenient to assume local-equilibrium in such models whenever possible. To assess whether this assumption is reasonable, a modeling approach accounting for coupled fluid flow and water-rock interaction is described that can be used to estimate spatial and temporal scale of local equiliblium. The approach is demonstrated for conditions involving groundwater flow in fractures at JNC's Kamaishi in-situ tests site, and is also used to estimate the travel time necessary for oxidizing surface waters to migrate to the level of a HLW repository in crystalline rock. The question of whether local equilibrium is a reasonable assumption must be addressed using an appropriate modeling approach. To be appropriate for conditions at the Kamaishi site using the modeling approach noted above, the fracture fill must closely approximate a porous medium, groundwater flow must be purely advective and diffusion of solutes across the fracture-host rock boundary must not occur. Moreover, the ...

An Estimation of influence of humic acid and organic matter originated from bentonite on samarium solubility

*; Sato, Haruo; *

JNC TN8400 99-059, 59 Pages, 1999/10

JNC-TN8400-99-059.pdf:1.54MB

Organic acids in groundwater are considered to form complexes and increase the solubility of radionuclides released from vitrified waste in a high-level radioactive waste (HLW) repository. To ivestigate whether the solubility of samarium (Sm) is influenced by organic substances, we measured Sm solubility in the presence of different organic substances and compared those values with results from thermodynamic predictions. Humic acid (Aldrich) is commercially available and soluble organic matter originated from bentonite were used as organic substances in this study. Consequently, the solubility of Sm showed a tendency to apparently increase with icreasing the concentration of humic acid, but in the presence of carbonate, thermodynamic predictions suggested that the dominant species are carbonate complexes and that the effect of organic substances are less than that of carbonate. Based on total organic carbon (TOC), the increase of Sm solubility measured with humic acid (Aldrich) was more significant than that in the case with soluble organic matter originated from bentonite. Since bentonite is presumed to include also simple organic matters of which stability constant for forming complexes is low, the effect of soluble organic matter originated from bentonite on the solubility of Sm is eonsidered to be less effective than that of humic acid (Aldrieh). Experimental values were compared with model prediction, propsed by Kim, based on data measured in a low pH region. Tentatively we calculated the increase in Sm solubility assuming complexation with humic acid. Trial calculations were carried out on the premise that the complexation reaction of metal ion with humic acid is based on neutralization process by 1-1 complexation. In this process, it was assumed that one metal ion coordinates with one unit of complexation sites which number of proton exchange sites is equal to ionic charge. Consequently, Kim's model indicated that carbonate complexes should be dominant ...

None

PNC TJ6622 97-001, 38 Pages, 1997/03

PNC-TJ6622-97-001.pdf:1.33MB

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Sazarashi, Masami*; Ikeda, Yasuhisa*; Kumagai, Mikio*; *; *

PNC TJ1564 96-002, 19 Pages, 1996/03

PNC-TJ1564-96-002.pdf:0.57MB

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PNC TJ1150 95-005, 16 Pages, 1995/03

PNC-TJ1150-95-005.pdf:0.42MB

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*

PNC TJ1211 95-006, 72 Pages, 1995/02

PNC-TJ1211-95-006.pdf:1.14MB

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Mukai, Satoru*; *; *

PNC TJ1214 94-008, 137 Pages, 1994/03

PNC-TJ1214-94-008.pdf:1.9MB

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Yui, Mikazu; Takeda, Seietsu; Komuro, Kosei*; Makino, Hitoshi; ; ; Ishiguro, Katsuhiko

PNC TN8410 92-166, 174 Pages, 1992/09

PNC-TN8410-92-166.pdf:4.22MB

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PNC TJ1281 92-002, 546 Pages, 1992/02

PNC-TJ1281-92-002.pdf:10.41MB

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