Study on retardation mechanism of {sup 3}H, {sup 99}Tc, {sup 137}Np and {sup 241}Am in compacted sodium bentonite
Conference
·
OSTI ID:62226
- Power Reactor and Nuclear Fuel Development Corp., Tokai-mura (Japan)
The apparent diffusion coefficients were measured at room temperature (about 23{degrees}C) under atmospheric condition by the one-dimensional non-steady state diffusion method for {sup 3}H, {sup 99}Tc, {sup 137}Cs, {sup 237}Np and {sup 241}Am in compacted sodium-bentonite saturated with water. Sodium-bentonite which, is commercially available as KunigelVi{reg_sign}, was used in this study. Experiments were carried out in the density range of 0.4-2.0({times} 10{sup 3}kg/m{sup 3}). Bentonite in the cell was prepared to be saturated with distilled water. The measured apparent diffusion coefficient decreases with increasing dry density of bentonite. That the apparent diffusion coefficient of {sup 3}H decreased as a function of dry density of bentonite appears to be the effect of the change of porous structure with dry density of bentonite. {sup 99}Tc is pertechnetate ion under atmospheric condition. Retardation for {sup 137}Cs may be caused by ion-exchange on bentonite. The sorption, anion-exclusion and molecular filtration are considered as a retardation mechanism for {sup 237}Np and {sup 241}Am because those dominant species are negatively charged and of large ionic size.
- OSTI ID:
- 62226
- Report Number(s):
- CONF-921101--Vol.294
- Country of Publication:
- United States
- Language:
- English
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