Determination of the secondary phases at the acidic LNW disposal

MRS Advances ◽  
2016 ◽  
Vol 1 (61) ◽  
pp. 4053-4059
Author(s):  
Irina Vlasova ◽  
Anna Romanchuk ◽  
Anna Volkova ◽  
Elena Zakharova ◽  
Igor Presnyakov ◽  
...  
Keyword(s):  
Acid Corrosion ◽  
Fission Products ◽  
Corrosion Products ◽  
Migration Behavior ◽  
Secondary Phases ◽  
High Sorption Capacity ◽  
High Sorption ◽  
Solid Phases ◽  
Precipitated Phases

ABSTRACTThe migration behavior of the long-lived actinides was studied under the conditions of the deep disposal of the acidic liquid nuclear waste (LNW). Composition of LNW varies significantly including acidic technological wastes (pH ∼2.4), which consist of sodium nitrate, acetic acid, corrosion products (Fe, Cr, Mn, Ni, Al), fission products and actinides. Corrosion products tend to precipitate under the LNW disposal conditions that favor forming of the phases with high sorption capacity towards actinides. Sands of reservoir bed have their own initial sorbent surfaces besides new secondary phases that have formed as a result of interaction with acidic LNW. The nearest to the injection well conditions are gradually changing from pH ∼2.4 till neutral values due to the dilution by groundwater with formation of new precipitated phases of corrosion products. The solid phases characterization is a necessary step on the path of knowledge of migration behavior of actinides. The secondary phases of both corrosion products and sands of reservoir bed under LNW disposal conditions were characterized using XRD, SEM and Mössbauer spectroscopy. The recent results of the analyses of the behavior of actinides (Pu. U, Np, Am) under the conditions of the injection of the acid LNW are presented in the paper.

Geochemical Simulation of Reaction Between Spent Fuel Waste Form and J-13 Water at 25°C and 90°C

1987 ◽  
Vol 112 ◽  
Author(s):  
Carol J. Bruton ◽  
Henry F. Shaw
Keyword(s):  
Yucca Mountain ◽  
Waste Form ◽  
Spent Fuel ◽  
Secondary Phases ◽  
Subsequent Reaction ◽  
Solution Composition ◽  
J 13 ◽  
Solid Phases ◽  
Precipitated Phases

AbstractGeochemical simulations of the degradation of spent fuel waste form in the presence of groundwater at the candidate Yucca Mountain, Nevada repository have been carried out to attempt to predict elemental concentrations in solution and to identify potential radionuclide-bearing precipitates. Spent fuel was assumed to dissolve congruently into a static mass of J-13 groundwater at 25°C and 90°C. No inhibitions to the precipitation and dissolution of secondary phases were assumed to exist. The elements Ac, Zr, Nb, Pd, Sm, Mo, Sb and Cm were not considered in the simulations because of a lack of thermodynamic data.Simulation results indicate that haiweeite, soddyite, Na2U2O7(c) and schoepite are potential U-bearing precipitates. Na2U2O7(c) is only predicted to occur at 90°C. U concentrations in solution and the identity of the U-bearing precipitate depend on the activity of SiO2(aq) in solution. U concentrations are limited to < 1 mg/kg when sufficient SiO2(aq) exists in solution to precipitate uranyl silicates. Depletion of SiO2(aq) in solution by the precipitation of silicates results in predicted increases of U concentrations to 87 and 619 mg/kg at 25°C and 90°C, respectively. Subsequent reaction and precipitation of schoepite cause U concentrations to decrease.Radionuclides other than U commonly precipitate as oxides in the simulations. The precipitation of solid phases appears to be extremely effective in limiting the concentrations of some radionuclides, such as Pu and Th, in solution. Concentrations of other elements are held constant (Sn) or are alternately held constant and then increase (Am, Ni, Np) as various solid phases precipitate and pH decreases from 8.5 to 6.5 at 25°C and 8.7 to 8 at 90°C. No solid phases containing Cs or Tc are predicted to form. Increasing the temperature from 25°C to 90°C does not impact greatly the identity of precipitated phases or solution composition, except in the case of U.A technique involving isotope dilution measurements may allow determination of the rates of spent fuel dissolution in future experiments.

Thiocarbamoyl chitosan as a novel sorbent with high sorption capacity and selectivity for the ions of gold(III), platinum(IV), and palladium(II)

2010 ◽  
Vol 59 (7) ◽  
pp. 1303-1306 ◽  
Author(s):  
A. V. Pestov ◽  
S. Yu. Bratskaya ◽  
A. B. Slobodyuk ◽  
V. A. Avramenko ◽  
Yu. G. Yatluk
Keyword(s):  
Sorption Capacity ◽  
High Sorption Capacity ◽  
High Sorption

scholarly journals The Valance Determination of Cerium Ions in α-SiAlON by Electron Energy Loss Spectroscopy Analysis

2008 ◽  
Vol 14 (S3) ◽  
pp. 19-22 ◽  
Author(s):  
H. Yurdakul ◽  
S. Turan
Keyword(s):  
Rare Earth ◽  
Ionic Radius ◽  
High Hardness ◽  
Engineering Properties ◽  
Secondary Phases ◽  
Sintering Additive ◽  
Valence States ◽  
Domain Boundaries ◽  
Spark Plasma

SiAlON ceramics have found applications in many different areas due to their excellent engineering properties such as high hardness, fracture toughness, good thermal shock and oxidation resistance. SiAlON exist mainly in two different polymorphs: a (MxSi12-(m+n)Al(m+n)OnN16-n; M: metal and rare earth cations, x≈0,35 and n≤1,35) and β (β-Si6-zAlzOzN8-z; 0≤z≤4). In general, stable alpha and beta phases separately as well as in combination of α and β are obtained by incorporation of metal and rare earth cations as sintering additives. The metal cations such as Li, Mg, Ca, Y, and most lanthanide cations with the exception of La, Ce, Pr and Eu are able to stabilise α-SiAlON structure. Ekstrom et al. 1991 found that cerium can not occupy interstitial sites in α-SiAlON structure due to the fact that ionic radius of Ce3+ (0.103 nm) is too large, whereas ionic radius of Ce4+ (0.080 nm) is too small to stabilise α-SiAlON structure. After this work, several studies carried out to incorporate cerium cations into α-SiAlON structure. It was shown that cerium cation alone can be incorporated into α-SiAlON if the samples are either fast cooled after sintering, or when the samples are spark plasma sintered. On the other hand, cerium can also be incorporated into the α-SiAlON structure when it is used as a sintering additive together with a smaller α-SiAlON stabiliser cation such as Yb or Ca. Similar results were observed in other multi-cation doped SiAlONS that non α-SiAlON stabiliser cations like Sr2+ (0.112 nm) and La3+ (0.106 nm) are able to stabilise α-SiAlON when used together with α-SiAlON stabiliser cations such as Ca or Yb. Although it was shown that cerium existed in mixed valance state at domain boundaries in Ce-doped and spark plasma sintered α-SiAlON, there is no work on the valance determination of cerium in sintered α-SiAlON which has no domain boundaries. Therefore, in this study; it was aimed to incorporate cerium into α-SiAlON structure by combining with Yb3+ and the determination of possible cerium valence states (Ce3+/Ce4+) in both α-SiAlON grains and secondary phases.

New Evidence for High Sorption Capacity of Hydrochar for Hydrophobic Organic Pollutants

2016 ◽  
Vol 50 (24) ◽  
pp. 13274-13282 ◽  
Author(s):  
Lanfang Han ◽  
Kyoung S. Ro ◽  
Ke Sun ◽  
Haoran Sun ◽  
Ziying Wang ◽  
...  
Keyword(s):  
Sorption Capacity ◽  
Organic Pollutants ◽  
High Sorption Capacity ◽  
High Sorption ◽  
New Evidence ◽  
Hydrophobic Organic Pollutants

Entrapment of radioactive uranium from wastewater by using fungus-Fe3O4 bio-nanocomposites

RSC Advances ◽  
2015 ◽  
Vol 5 (52) ◽  
pp. 41611-41616 ◽  
Author(s):  
La Li ◽  
Mingze Xu ◽  
Maksim Chubik ◽  
Marianna Chubik ◽  
Alexander Gromov ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Sorption Capacity ◽  
Culture Method ◽  
High Sorption Capacity ◽  
High Sorption ◽  
Magnetically Separable

Magnetically separable adsorbents with high sorption capacity for nuclear wastewater treatment have been successfully synthesized on the basis of fungus-Fe3O4 nanoparticle bio-nanocomposites through a simple co-culture method.

scholarly journals Experimental Determination of the Antineutrino Spectrum of the Fission Products ofU238

2014 ◽  
Vol 112 (12) ◽  
Author(s):  
N. Haag ◽  
A. Gütlein ◽  
M. Hofmann ◽  
L. Oberauer ◽  
W. Potzel ◽  
...  
Keyword(s):  
Experimental Determination ◽  
Fission Products ◽  
Antineutrino Spectrum

Peat as Sorbent for Cu2+ and Cr3+ Ions

2011 ◽  
Vol 50 (1-2) ◽  
pp. 149-158 ◽  
Author(s):  
A. Robalds ◽  
M. Klavins ◽  
A. Zicmanis
Keyword(s):  
Trace Elements ◽  
Industrial Waste ◽  
Metal Removal ◽  
Waste Waters ◽  
Natural Sorbent ◽  
High Sorption Capacity ◽  
Terrestrial Life ◽  
High Sorption ◽  
The Common ◽  
Insoluble Compounds

Peat as Sorbent for Cu2+ and Cr3+ Ions Heavy metals as trace elements can often be found in industrial waste waters, and their discharge to the environment is a significant threat due to their acute toxicity to the aquatic and terrestrial life. The common methods used for removal of toxic metals and trace elements from the municipal and industrial waste waters are based on their adsorption onto insoluble compounds - sorbents. Synthetic sorbents usually are quite expensive; therefore, as a prospective approach to the metal removal, the use of a natural sorbent - peat - was tested. Peat as sorbent was proved to have a relatively high sorption capacity in respect to the studied metal ions, it can be used batchwise and in a dynamic regime and is a relatively robust and reliable sorbent regarding pH, the ionic strength, and the amounts of sorbed metal.

Alteration of Natural Uranyl Oxide Hydrates in Si-Rich Groundwaters: Implications For Uranium Solubility

1991 ◽  
Vol 257 ◽  
Author(s):  
R.J. Finch ◽  
R.C. Ewing
Keyword(s):  
Corrosion Products ◽  
Dissolved Silica ◽  
Uranyl Phosphates ◽  
Uranyl Silicates ◽  
Solid Phases ◽  
And Control

ABSTRACTThe uranyl oxide hydrates are common initial corrosion products of uraninite (nominally U02+x) during weathering. In the presence of dissolved silica these early-formed phases alter to uranyl silicates (most commonly soddyite, U2SiO8-2H2O, and uranophane, CaU2Si2O11·6H2O). Uraninite, however, usually contains radiogenic Pb, and the earlyformed Pb-poor uranyl oxide hydrates alter incongruously to uranyl silicates plus Pb-enriched uranyl oxide hydrates such as curite. Similar to dissolved silica, radiogenic Pb may also serve to limit the mobility of U in nature by fixing U in solid phases. Curite may also play an important role in the formation of uranyl phosphates, which are significantly less soluble than the uranyl silicates, and control U solubility in many groundwaters associated with altered U ore.

Fabrication of a phosphorylated graphene oxide–chitosan composite for highly effective and selective capture of U(vi)

2017 ◽  
Vol 4 (9) ◽  
pp. 1876-1886 ◽  
Author(s):  
Yawen Cai ◽  
Chunfang Wu ◽  
Zhiyong Liu ◽  
Linjuan Zhang ◽  
Lanhua Chen ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Sorption Capacity ◽  
High Sorption Capacity ◽  
Highly Effective ◽  
High Sorption ◽  
Chitosan Composite

The synthesized GO–CS–P exhibits ultrafast removal kinetics, high sorption capacity and great selectivity towards U(vi).

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