JOPSS - Search Results

JAEA Reports

None

; ; *

JNC TY7430 2000-001, 57 Pages, 2000/03

JNC-TY7430-2000-001.pdf:2.17MB

no abstracts in English

JAEA Reports

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 ...

JAEA Reports

Corrosion bihavior of carbon steel in high-temperature sodium compounds; Recommended equation for corrosion rate of the carbon steel in sodium compounds (Na $_{2}$ O $_{2}$ -NaOH System)

Yoshida, Eiichi; Aoto, Kazumi; Hirakawa, Yasushi;

JNC TN9400 2000-024, 42 Pages, 1999/10

JNC-TN9400-2000-024.pdf:1.63MB

For the purpose of improving the reliability of evaluation, the corrosion rate equation of the carbon steel SM400B (JIS G3106) in the high-temperature sodium compounds (NaOH-Na $_{2}$ 0 $_{2}$ system) was revised. ln this revision, the data acquired after 1997 was used. Based on the experimental results, the evaluation was made to be an approach to the following; (1)Metal loss of carbon steel in NaOH-Na $_{2}$ 0 $_{2}$ system was evaluated as increases in exposure to the time, which is linear rate law. (2)There were no significant effects of the experiment atmosphere and mixing speed of the reagent on corrosion rate. (3)The concentration of Na $_{2}$ 0 $_{2}$ in sodium compound is considered for the evaluation. The concentration under experiment is made to be the over concentration necessary for maintaining the dominant reaction between Fe and Na $_{2}$ 20 $_{2}$ . As a result of the evaluation, the additional data are 67 points. The data for the revision of the evaluation equation became the total of 105 points, when existing data of 38 points were added. The statistical evaluation of 105 points was carried out, and following recommended equation was obtained. C $_{R}$ = C exp(-Q/RT) Where; C $_{R}$ : Corrosion rate, mm/h C : Material constant Q : Apparent activation energy, cal/mol R : Gas constant, 1.986 cal/mol K T ; Absolute temperature, K Q = 9.61 kcal/mol C = 148.29 (average), 262.11 (99% UCL), 83.90 (99% LCL)