Uranium Dissolution and Geochemical Modeling in Anoxic and Oxic Solutions

MRS Advances ◽  
2017 ◽  
Vol 2 (13) ◽  
pp. 705-710 ◽  
Author(s):  
Carol M. Jantzen ◽  
Cory L. Trivelpiece
Keyword(s):  
Geochemical Modeling ◽  
Deionized Water ◽  
High Level Waste ◽  
Profound Impact ◽  
Anoxic Conditions ◽  
The World ◽  
Ph Conditions ◽  
High Level ◽  
Colloidal Species ◽  
Uranium Species

ABSTRACTHigh Level Waste (HLW) glasses are to be stored in deep geologic repositories around the world. Some potential repository geologies have oxidizing groundwaters while some have reducing or anoxic groundwaters. The differences in the oxidizing potential of the groundwater, expressed as groundwater Eh, which has a profound impact on the release of multivalent species such as iron and uranium from the glass. Static leach testing of monolithic glass samples (ASTM C1220) doped with uranium were performed at 90°C in an Ar glovebox under anoxic and oxic conditions. Tests were performed in both deionized water and in simulated basaltic groundwater that was pre-equilibrated at low Eh. Geochemical modeling of the measured Eh-pH conditions from the oxic and anoxic experiments using Geochemist’s Workbench software, suggested that different colloidal species control the release of uranium species under oxic and anoxic conditions.

Near Field Radionuclide Concentrations: Sorption or Solubility Constrained?

2001 ◽  
Author(s):  
Bernhard Kienzler ◽  
Peter Vejmelka ◽  
Volker Metz
Keyword(s):  
Portland Cement ◽  
Performance Assessment ◽  
Geochemical Modeling ◽  
Coal Fly Ash ◽  
Near Field ◽  
High Level Waste ◽  
Sorption Behavior ◽  
Geochemical Environment ◽  
Backfill Materials ◽  
High Level

Abstract The amount of mobile radionuclides is controlled by the geochemical isolation potential of the repository. Many investigations are available in order to determine the maximal radionuclide concentrations released from different waste forms of specific disposal strategies for disposal in rock salt formations. These investigations result in reaction (dissolution) rates, maximum concentrations, and sorption coefficients. The experimental data have to be applied to various disposal strategies. The case studies presented in this communication cover the selection, the volumes, and the composition of backfill materials used as sorbents for radionuclides. As an example, for brown coal fly ash (BFA) - Q-brine systems, sorption coefficients were measured as well as solublilities of several actinides and other long-lived radionuclides. Dissolved CO32− was buffered to negligible concentration by the presence of high amount of Mg in solution. In the sorption experiments Pu, Th, Np, and U concentrations close or below detection limit were obtained. Concentrations in the same ranges are computed by means of geochemical modeling, if precipitation of “simple” tetravalent hydroxides (An(OH)4(am) phases) is assumed. In the case of U in a Portland cement dominated geochemical environment, measured U(VI) concentration corresponds to the solubility of hexavalent solids, such as Na2U2O7. A similar behavior of U was observed in high-level waste glass experiments. Experiments investigating sorption behavior of corroded cement showed that in the case of application of a sufficient large inventory of actinides, measured concentrations were found to be independent of the inventory. In this case, measured concentrations were controlled by solid phases. If smaller actinide inventories were applied, resulting concentrations were found to be below concentrations constrained by well-known solids. Here, a more or less pronounced sorption of the radioactive elements was observed. The radionuclide concentrations determined in the BFA “sorption” experiments are found to be close to the detection limits. For this reason, it is not possible to extrapolate the radionuclide behavior to lower concentrations. We cannot distinguish, if sorption or precipitation controls measured radionuclide concentrations. However, in the presence of reducing materials such as BFA, solubilities of tetravalent actinides and of Tc(IV) represent a realistic estimation of the maximal element concentrations needed in performance assessment studies. The concentrations of these redox sensitive elements are controlled by precipitation of An(OH)4(am) phases for disposal concepts considered in German salt formations. Under this assumption, quantities such as solid-solution ratios used in (sorption) experiments do not affect the mobilization of the radionuclides. Additional conclusions can be drawn from comparison of the findings for the redox sensitive elements in the BFA / portland cement brine systems: We can assume that expected actinide and technetium concentrations in the near-field of radioactive wastes are affected by the total inventory of radionuclides in the disposal room. Sorption will be relevant, if the total dissolved radionuclide concentration remains below the maximal solubility defined by the solid radionuclide phase which is stable in the geochemical environment. In contrast to the portland cement system, the relevant radionuclide phase are most probably tetravalent hydroxides in the BFA systems. These conclusions are of high importance to performance assessment for the radioactive waste repository systems, because they restrict the applicability of sorption models in the near field of the waste.

scholarly journals The Reaction of SRL 202 Glass in J-13 and DIW

1992 ◽  
Vol 294 ◽  
Author(s):  
W. L. Ebert ◽  
J. K. Bates ◽  
E. C. Buck
Keyword(s):  
Stainless Steel ◽  
Reaction Rates ◽  
Deionized Water ◽  
High Level Waste ◽  
Similar Reaction ◽  
304L Stainless Steel ◽  
Ph Values ◽  
Stainless Steel Vessel ◽  
J 13 ◽  
High Level

ABSTRACTStatic leach tests were performed in both 304L stainless steel and Teflon vessels using a synthetic high-level waste glass with either deionized water (DIW) or a tuff groundwater solution as the leachant to assess the effects of the vessel and the initial leachant composition on the extent and nature of the glass reaction. The tests were performed using monolith samples at 340 m−1 and crushed samples at 2000 m−1 for times up to 1 year. The results show less silicon is released from the glass into the groundwater solution than into DIW at both high and low glass surface area/leachant volume ratios (SA/V), but the alkali metal and boron releases are not affected by the leachant used. Tests performed in a stainless steel vessel resulted in slightly lower leachate pH values, but similar reaction rates to those performed in a Teflon vessel, as measured by the boron release. Blank tests with DIW or EJ-13 in the vessels showed the Teflon vessels to release small amounts of fluoride (1 to 2 ppm) and to acidify the DIW slightly (4.0 < pH < 5.6). The pH values of blank tests with EJ-13 increased from 8.2 to about 8.6 in steel and to about 9.2 in Teflon vessels. The slightly higher pH values attained in Teflon vessels are attributed to outgassing of CO2 during the test.

scholarly journals Accelerated Leach Tests of SRL-165 High-Level Waste Glass in Deionized Water

1989 ◽  
Vol 26 (4) ◽  
pp. 441-448 ◽  
Author(s):  
Hiroshi KAMIZONO ◽  
David E. CLARK ◽  
Alexander R. LODDING
Keyword(s):  
Deionized Water ◽  
Waste Glass ◽  
High Level Waste ◽  
High Level

The Mechanisms for Hydrothermal Leaching of Nuclear Waste Glasses: Properties and Evaluation of Surface Layers

1981 ◽  
Vol 11 ◽  
Author(s):  
GÜnter Malow
Keyword(s):  
Environmental Parameters ◽  
Specific Weight ◽  
Deionized Water ◽  
High Level Waste ◽  
Surface Layers ◽  
Leach Rate ◽  
Weight Losses ◽  
Corrosion Mechanisms ◽  
High Level ◽  
Glass Compositions

Remobilization of solidified high-level waste by corrosion and transport of radionuclides by groundwater are the only likely events for radioactivity to find its way back to the environment. The interaction of the waste form with aqueous solutions is the most important mechanism and must be known for safety and risk analysis. It has been shown that the activity release depends on a number of experimental and environmental parameters. The corrosion mechanisms of the waste forms control the leach rate of individual components. Of particular importance to the resistance against water attack of various glass compositions is the formation of layers on the glass surface. The results for leaching in deionized water reveafed that the mechanism was strongly influenced by the formation of a surface layer which determined the further attack on the glass. In this work the specific weight losses of the glass after leaching in rock salt and MgCl2–MgSO4-NaCl-KCl solutions were measured and surface layers investigated.

Her Majesty Queen Rania Al Abdullah

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Education System ◽  
Ministry Of Education ◽  
Childhood Experiences ◽  
The Sustainable Development ◽  
American University ◽  
The North ◽  
The World ◽  
Development Goals ◽  
High Level ◽  
Education And Development

“The real treasure is in the minds of our children, and all we have to do is extract it.” Her Majesty Queen Rania Al Abdullah writes in website Queen Rania Foundation For Education And Development www.qrf.org/en. Rania Al Yassin was born on August 31, 1970. She obtained her Bachelor’s degree in Business Administration from the American University of Cairo in 1991. She applied this, first, to a banking career in Jordan and, later, to the information technology sector. After marrying Prince Abdullah bin Al Hussein on June 10, 1993, they went on to have four children: Prince Hussein, Princess Iman, Princess Salma, and Prince Hashem. In addition to being a wife and mother, Queen Rania works hard to lift the lives of Jordanians by supporting their endeavours and helping to create new opportunities for them. Locally, she is committed to breathe new life into the public education system; empower communities and women especially through microfinance initiatives; protect children and families; and drive innovation, technology and entrepreneurship, especially amongst young people. Internationally, Queen Rania is an advocate for tolerance, compassion and bridge building between people of all cultures and backgrounds. Her efforts to simultaneously challenge stereotypes of Arabs and Muslims, and promote greater understanding and acceptance between people of all faiths and cultures, have won her global recognition. Her Majesty’s passion is education. She believes that every Jordanian girl and boy, and all children, should have access not only to stimulating classrooms and modern curricula, but inspiring teachers and technology that can connect Jordan’s children to the world and the world to Jordan’s children. Her efforts in the education sector complement the work of the Ministry of Education through initiatives such as the Jordan Education Initiative, the Queen Rania Teachers Academy, Madrasati, Edraak and others. To realize these and so much more, Queen Rania has encouraged private sector partners to drive improvements and strengthen the foundations of Jordan’s education system. Queen Rania is also a global voice for access to quality education for children around the world. In 2009, Her Majesty championed the 1 Goal campaign for education; she is Honorary Chair of the UN Girl’s Education Initiatives and has advocated access to education in forums and gatherings around the world. Her work and her efforts to improve the learning opportunities for children have been recognized at the highest levels, nationally, regionally and internationally. Additionally, through her position on their boards, Her Majesty contributes to the work of the United Nations Fund and the World Economic Forum. She is the Eminent Advocate for UNICEF; and she was part of the UN appointed High Level Panel who advised on the shape and content of the Sustainable Development Goals which aim to improve the lives of millions of people before 2030. In recognition of her work, Her Majesty has humbly accepted many awards, locally, regionally and globally. These include the Walther Rathenau Award from the Walther RathenauInstitut in Germany for her efforts to greater peace and understanding; the James C. Morgan Global Humanitarian Award from Tech Awards, USA; the Arab Knight of Giving Award from Arab Giving Forum, UAE; the North South Prize by the North South Prize, Portugal; as well as the YouTube Visionary Award. Her Majesty authored several books primarily for children including the Sandwich Swap, which was inspired by her own childhood experiences.

Global warming influences dynamics of plague’s epidemic manifestations in XX-XXI centuries

2017 ◽  
pp. 38-40
Author(s):  
E.S. Zenkevich ◽  
N.V. Popov
Keyword(s):  
Global Warming ◽  
20Th Century ◽  
Modern Trend ◽  
Climate Fluctuations ◽  
The World ◽  
Low Incidence ◽  
High Level

During the second half of 20th century, a high level of plague incidence in the world was in 1960–1979 and 1990–2009. The significant decrease of infection cases was in 1950–1959, 1980–1989, 2010–2015. It is noticed, that the observed cyclical nature of the alternation of high and low incidence plague’s periods, in many respects related to modern trend of climate fluctuations.

SYNONYMY OF STABLE PHRASES IN THE DICTIONARY OF SMOLENSK DIALECTS: THE ANALYSIS EXPERIENCE

2019 ◽  
pp. 122-132
Author(s):  
Nina Maksimchuk
Keyword(s):  
Native Speakers ◽  
National Language ◽  
Cultural Value ◽  
Semantic Structure ◽  
Spiritual World ◽  
Key Word ◽  
The World ◽  
Volumetric Representation ◽  
High Level ◽  
Linguistic Units

The attention of modern linguistics to the study of verbal representatives of the mental essence (both individual and collective one) of the native speakers involves an appeal to all subsystems of the national language where territorial dialects take a significant part. The analysis of dialect linguistic units possessing linguistic and cultural value is considered as a necessary way for the study of people’s worldview and perception of the world, national mentality as a whole. The ability of stable phrases (phraseological units) to preserve and express a native speaker’s attitude to the world around them is the basis for the use of the analysis of folk phraseology as a way of penetration into a speaker’s spiritual world. Volumetric representation of the external and internal peculiarities of stable phrases allows the author to get their systematization in the form of phraseosemantic field consisting of different kinds singled out in phraseosemantic groups. The article deals with stable phrases of synonymic value recorded in the Dictionary of Smolensk dialects and stable phrases forming a phraseosemantic group. These phrases are analyzed taking into account the semantic structure of the key word, the characteristics of the dependent word, and the method of forming phraseological semantics. On the example of the analysis of phrases with the key word «bit’» and a synonymic series with the semantic dominant «bezdel’nichat’», the article discusses the peculiarities of phraseological nomination in Smolensk dialects and confirms a high level of connotativity and evaluation in the folk phraseology.

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