A Column Experiment for the Study of Colloidal Radionuclide Migration in Gorleben Aquifer Systems

Kim, J. I.; Delakowitz, Bernd; Zeh, P.; Klotz, D.; Lazik, D.

doi:10.1524/ract.1994.6667.special-issue.165

Cited by 67 publications

(26 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…mean value of log (LC × β 1.IV ) = 11.7 ± 0.3 is obtained with a 95% confidence interval. 6 It is to be noted that the use of other constant sets [57, 59, 61] induces only minor changes, since the speciation of thorium (IV) is controlled by acetate complexation.…”

Section: Formation Of Thha(iv)mentioning

confidence: 99%

“…Experimental difficulties have often prevented from obtaining reliable results on reduced states of uranium, neptunium or plutonium. Furthermore, the redox properties of humic substances [3][4][5] have led to confusing results for protactinium [6], neptunium [7,8], plutonium [9][10][11][12] and other elements [13][14][15][16][17][18][19], even if the use of ligands to stabilise redox state is well known in the nuclear industry [20][21][22][23]. Otherwise, the reduction of uranium (VI) by HS has not been clearly observed up to now [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Reiller¹

2005

Radiochimica Acta

View full text Add to dashboard Cite

To cite this version:Pascal E. Reiller. Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model. AbstractThe complexation of redox sensitive elements by humic acid (HA), described through the charge neutralisation model (CNM) has been reviewed in order to have a comprehensive scope. The data acquired in HUMICS program on thorium (IV), and data available in the literature, were reinterpreted according to the CNM, and adapted to uranium (IV), neptunium (IV) and plutonium (IV) through analogy in order to draw a boundary prediction. Otherwise, available data obtained in the framework of the CNM were used, or adapted if necessary, for other redox states when the analogy is justified, i.e. Am The obtained speciation diagrams indicate that, when (HA) = 100 mg/L, redox sensitive actinides should be reduced to their +IV state when E H ≤ 650 mV/SHE for plutonium, E H ≤ 100 mV/SHE for neptunium and E H ≤ -20 mV/SHE for U. Plutonium could be present as mixtures of plutonium (III) and (IV) depending on the pH value in reducing ground waters -150 ≤ E H (mV/SHE) ≤ 150. The known reduction of neptunium (V) to neptunium (IV) in Gorleben ground waters seems also well represented, so does the stability of uranium (VI) in humic solution when E H ≥ 100 mV/SHE. Conversely, the known association of plutonium (VI) in marine systems are not satisfactorily represented, so does is the uranium behaviour under reducing conditions. Experiments under well-controlled conditions are still needed to ascertain the plutonium and uranium comportment in the presence of humic acid. *

show abstract

Section: Formation Of Thha(iv)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Reiller¹

2005

Radiochimica Acta

View full text Add to dashboard Cite

show abstract

“…Pa, Np and Pu (34)(35)(36)(37)(38)(39)(40), due either to the low redox potential of aqueous solution of HA (41)(42)(43)(44) or/and by the preferential complexation of multicharged cations (45). The +IV oxidation state of the actinides seems to be stabilised by the humic complexation.…”

Section: Introductionmentioning

confidence: 99%

Influence of Addition Order and Contact Time on Thorium(IV) Retention by Hematite in the Presence of Humic Acids

Reiller¹,

Casanova²,

Moulin

2005

Environ. Sci. Technol.

View full text Add to dashboard Cite

The influence of addition order and contact time in the system hematite (α-Fe 2 O 3 ) -humic acid (HA) -thorium (IV) was studied in batch experiments. Thorium (IV) is considered here as a chemical analogue of other actinides (IV). The sorption isotherms were acquired varying pH in the range 2-10, and HA concentration in the range 1-100 mg/L. As already observed by numerous authors, thorium (IV) retention was hindered when HA and hematite were equilibrated beforehand during 24 hours. As it has been observed in a previous study, this 2 effect was drastic when the ratio between humic and surface (iron oxide) sites exceeds a critical value. However, when HA were added after a 24 hours equilibration of the hematitethorium (IV) system, thorium (IV) was barely desorbed from the iron oxide surface.Furthermore, no drastic effect of the ratio between humic and surface sites could be evidenced, as the increase of HA concentration only results in a slight monotonic decrease in Th(IV) retention. Increasing contact time between components of the systems only indicated slight Th(IV) retention variation. This was interpreted as a consequence of slow kinetic controls of both the Th(IV)-HA complexation and HA-hematite sorption.

show abstract

“…rock salt may reach waste packages so that nuclides might be released (Warnecke et al, 1984(Warnecke et al, , 1994. Therefore, for the performance of a longterm safety assessment the barrier function of the geological formations overlying the salt dome have been studied by batch, column and diffusion experiments (Lieser et al, 1990;Meier et al, 1992Meier et al, , 1993Meier et al, , 1994Meier et al, , 1995Hollmann and Tittel, 1993;Kim et al, 1994;Warnecke et al, 1994).…”

mentioning

confidence: 99%

Modeling of colloid-associated radionuclide transport in porous groundwater aquifers at the Gorleben site, Germany.

Meier

Zimmerhackl²,

Zeitler³

2003

Geochem. J.

View full text Add to dashboard Cite

Results are presented which have been obtained in prediction studies on the colloid-associated transport of radionuclides through porous groundwater aquifers overlying as geochemical barrier the planned nuclear repository site at Gorleben, Germany. The studies incorporate three-phase retardation factors for 227 Ac, 228 Th, 232 U and 210 Pb in site-specific groundwater aquifers containing humic colloids and efficiencies for Brownian deposition of colloidal carriers onto immobile sedimentary grains. It is shown that colloidbound radionuclide migration can be approximately modeled by using the basic advection-dispersion transport equation modified with three-phase retardation coefficients and colloid-chemical attachment factors due to the presence of multiple phases, i.e., fluid, colloid and immobile solid. Moreover, results of sitespecific assessment studies indicate that the transport of colloid-associated radionuclides in porous groundwater aquifers overlying the Gorleben salt dome may not occur over long distances, provided that the nuclides are transported by porous flow only. rock salt may reach waste packages so that nuclides might be released (Warnecke et al., 1984(Warnecke et al., , 1994. Therefore, for the performance of a longterm safety assessment the barrier function of the geological formations overlying the salt dome have been studied by batch, column and diffusion experiments (Lieser et al

show abstract

A Column Experiment for the Study of Colloidal Radionuclide Migration in Gorleben Aquifer Systems

Cited by 67 publications

References 0 publications

Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Prognosticating the humic complexation for redox sensitive actinides through analogy, using the charge neutralisation model

Influence of Addition Order and Contact Time on Thorium(IV) Retention by Hematite in the Presence of Humic Acids

Modeling of colloid-associated radionuclide transport in porous groundwater aquifers at the Gorleben site, Germany.

Contact Info

Product

Resources

About