Effects of Water Chemistry on the Leach Resistance of Synroc C

1983 ◽  
Vol 26 ◽  
Author(s):  
J. L. Woolfrey ◽  
D. M. Levins
Keyword(s):  
Water Chemistry ◽  
Flow Rate ◽  
Volume Ratio ◽  
Chemical Durability ◽  
Borosilicate Glasses ◽  
Solution Composition ◽  
Leach Rate ◽  
Saturation Effects ◽  
Ph Range ◽  
Temperature Surface

ABSTRACTThe chemical durability of SYNROC C has been measured as a function of repository conditions, namely, temperature, surface/volume ratio, groundwater pH and composition. The leach rate of SYNROC C is less dependent on temperature than borosilicate glasses; activation energies range from 15-25 kJ mol-1 compared to 33-74 kJ mol-1 for glass. The rate of release from SYNROC C is very low and independent of solution composition for the solutions studied. There is little variation in leach rate over the pH range 4-9, but at pH 2 the rate is up to 10 times higher. SYNROC C leach rate is independent of flow rate or surface/volume ratio for the mobile waste elements because of the unimportance of solution saturation effects owing to the low concentration of dissolved solids. The differential leach rate decreases rapidly with time because, after initial leaching from grain boundaries and metastable minor phases, the highly insoluble matrix protects the more leachable elements from further attack.

Chemical Stability of Simiulated HLW Forms in Contact With Clay Media

1981 ◽  
Vol 11 ◽  
Author(s):  
P. Van Iseghem ◽  
W. Timmerans ◽  
R. De Batist
Keyword(s):  
Corrosion Behaviour ◽  
Volume Ratio ◽  
Water Mixture ◽  
Borosilicate Glasses ◽  
Corrosion Stability ◽  
Corrosion Rates ◽  
Waste Forms ◽  
Reference Medium ◽  
Saturation Effects ◽  
Solution Volume

ABSTRACTThe corrosion stability of six simulated HLW forms proposed by several European countries (five borosilicate glasses and one borosilicate glass ceramic) in contact with different media relating to the clay disposal has been investigated for periods up to 80 days and at a surface area to solution volume ratio of 1 cm−1 under non de-aerated conditions. In the reference medium distilled water the corrosion stabilities are largely determined by saturation effects for elements such as Si, Ca, Mg, Sr, Fe and U. Si saturation is found to be enhanced by a large Al2O3 concentration in the glass. In the clay-water mixture these saturation effects are much less predominant. Wet clay attacks the waste forms faster than the clay-water mixture, although the corrosion rates tend to decrease with time in both clay media. In general, no simple Arrhenius-type temnnerature dependence for the corrosion behaviour is found for the interval between 40 and 200°C.

Aluminophosphate Glasses with High Sulfate Content

1994 ◽  
Vol 353 ◽  
Author(s):  
Sergey V. Stefanovsky ◽  
Igor A. Ivanov ◽  
Anatolii N. Gulin
Keyword(s):  
Diffusion Coefficients ◽  
Glass Structure ◽  
Chemical Durability ◽  
Electric Resistivity ◽  
Melting Points ◽  
Sulfate Content ◽  
Leach Rate ◽  
High Sulfate ◽  
Aluminophosphate Glasses ◽  
And Diffusion

AbstractTo immobilize a high sulfate radioactive wastes a system Na2O-A12O3-P2O5-SO3 has been chosen as one where glasses have a relatively low melting points and good chemical durability. Glasses within partial system 44 Na2O, 20 A12O3 (36-x) P2O5 x SO3 have been prepared at 1000 °C. A possibility of assimilation up to 12 mole % of SO3 has been established. The basic properties of sulfate-containing glasses as density, microhardness, thermal expansion coefficient, transformation and deformation temperatures, viscosity, electric resistivity, leach rate of ions and diffusion coefficients of 22Na, 35S, 90Sr and 137Cs have been measured. Glass structure by infrared and EPR spectroscopies has been investigated.

scholarly journals Investigation of Borosilicate Glasses with Simulated HLW Components and Determination of Their Chemical Durability

2021 ◽  
Vol 8 (1) ◽  
pp. 20218105
Author(s):  
S. M. Shaydullin ◽  
E. A. Belanova ◽  
P. V. Kozlov ◽  
M. B. Remizov ◽  
E. M. Dvoryanchikova
Keyword(s):  
Chemical Durability ◽  
Current Status ◽  
Borosilicate Glasses ◽  
Radiochemical Plant ◽  
Technical Solutions

The paper discusses the current status of the HLW vitrification technology applied at the radiochemical plant of the Mayak PA. Conceptual and technical solutions proposed to develop the technology of vitrification of various types of liquid HLW at the Mayak PA are presented. Compositions of borosilicate glasses with HLW components are described, temperatures of their melting and easy pouring are determined. Chemical durability parameters obtained for the borosilicate glasses are provided.

Stimulation of Plasma Thyroxine Levels by Novel Water Chemistry during Smoltification in Chinook Salmon (Oncorhynchus tshawytscha)

1990 ◽  
Vol 47 (8) ◽  
pp. 1513-1517 ◽  
Author(s):  
Timothy L. Hoffnagle ◽  
Albert J. Fivizzani
Keyword(s):  
Water Chemistry ◽  
Flow Rate ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Water Source ◽  
Control Fish ◽  
Exposed Fish ◽  
Freshwater Population ◽  
Artificial Photoperiod ◽  
Stimulation Of

The separate influences of changes in water chemistry and flow rate on plasma thyroxine levels were assessed in a freshwater population of chinook salmon (Oncorhynchus tshawytscha) undergoing smoltification. Fish subjected to a change in water source had plasma thyroxine levels significantly greater than those of controls on several sampling dates. Maximum levels were observed 10 d after water change. Conversely, plasma thyroxine levels in fish for which the flow rate was increased showed little change and were never significantly different from controls. Plasma thyroxine levels were greater in fish held under a natural rather than artificial photoperiod but the patterns of change were similar in the two groups. Control fish transported to a new hatchery and novel water source attained plasma thyroxine levels which were even greater than those of novel water-exposed fish at the original hatchery. The results indicated that altered water chemistry rather than increased flow rate was the stimulus for the elevation in plasma thyroxine levels associated with smoltification in these chinook salmon.

Effects of water chemistry and flow rate on arsenate removal by adsorption to an iron oxide-based sorbent

2008 ◽  
Vol 42 (18) ◽  
pp. 4629-4636 ◽  
Author(s):  
Hui Zeng ◽  
Maiko Arashiro ◽  
Daniel E. Giammar
Keyword(s):  
Iron Oxide ◽  
Water Chemistry ◽  
Flow Rate

Chemical Durability of High Burnup Lwr-Spent Fuel in Concentrated Salt Solutions

1993 ◽  
Vol 333 ◽  
Author(s):  
A. Loida ◽  
B. Grambow ◽  
P. Dressier ◽  
K. Friese ◽  
H. Geckeis ◽  
...  
Keyword(s):  
Surface Area ◽  
Volume Ratio ◽  
Sample Surface ◽  
Solution Concentration ◽  
Reaction Rates ◽  
Spent Fuel ◽  
Intrinsic Dissolution ◽  
Fine Grained ◽  
High Burnup ◽  
Saturation Effects

ABSTRACTHigh-burnup (<50 MWd/kgU) spent fuel samples of various sizes were exposed to NaCl solutions under static, anaerobic and reducing conditions. The accumulated corrosion time was about 200 days. Gas phase and leach solutions were analyzed. By dissolving mm sized fragments in large volumes of solution, saturation effects were avoided and upper limits for intrinsic dissolution rates of about 5-20 mg/(m2d) were measured. Surface area normalized reaction rates were significantly lower when using fine grained fuel powder (estimated sample surface area to solution volume ratio S/V ca. 3000 m-1), indicating saturation effects. The maximum concentrations of Pu and Am in the tests are close to reported solubility limited concentrations in pure 5m NaCl solutions in the absence of radiolysis effects. The presence of iron effectively reduces the solution concentration of all measured radionuclides (except Cs).

scholarly journals Differential Pulse Polarographic Determination of Lead in Complex Materials after Adsorption of Its N-Methylethylxanthocarbamate Complex on Microcrystalline Naphthalene or on NMethylethylxanthocarbamate–Benzyldimethyltetradecylammonium–Naphthalene Adsorbent

2002 ◽  
Vol 85 (3) ◽  
pp. 712-718
Author(s):  
Mohammad Farid Hussain ◽  
Anil Kumar Sangahi ◽  
Iqbal Ahmad ◽  
Bal Krishan Puri
Keyword(s):  
Flow Rate ◽  
Signal To Noise Ratio ◽  
Differential Pulse ◽  
Correlation Factor ◽  
Differential Pulse Polarography ◽  
Pulse Polarography ◽  
Relative Standard ◽  
Ph Range ◽  
Microcrystalline Naphthalene

Abstract Lead is quantitatively adsorbed as the lead N-methylethylxanthocarbamate (MEXC)–benzyldimethyltetradecylammonium (BDTA) ion pair complex on microcrystalline naphthalene in the pH range 4.0–11.0. The metal is desorbed with HCl and determined by differential pulse polarography. Alternatively lead can be quantitatively adsorbed on the adsorbent (MEXC–BDTA–naphthalene) packed in a column at a flow rate of 1–2 mL/min and determined similarly. Dissolved oxygen is removed by adding a few milliliters of 4% NaBH4 solution. The detection limit is 0.12 μg/mL at the minimum instrumental settings (signal-to-noise ratio, 2). Linearity was obtained over the concentration range 0.3–20.0 μg/mL with a correlation factor of 0.9998 and a relative standard deviation of ± 0.98%. Various parameters, such as the effect of pH, volume of aqueous phase, flow rate, and the interference of a large number of metal ions and anions, were studied in detail to optimize the conditions for the trace determination of lead in various standard alloys, standard biological materials, and environmental samples.

Effects of Oxygen Flow Rate on Nanostructured ZnO Thin Films

2013 ◽  
Vol 667 ◽  
pp. 333-337
Author(s):  
S. Ahmad ◽  
N.D. Md Sin ◽  
M.N. Berhan ◽  
Mohamad Rusop Mahmood
Keyword(s):  
Thin Films ◽  
Flow Rate ◽  
Volume Ratio ◽  
Rf Magnetron Sputtering ◽  
Deposition Process ◽  
Oxygen Flow Rate ◽  
Oxygen Flow ◽  
Zno Thin Films ◽  
Average Thickness ◽  
X Ray

Zinc Oxide (ZnO) thin films were deposited on thermally oxidized SiO2 by varying the oxygen flow rate. The deposition process were done using radio frequency (RF) magnetron sputtering at various oxygen flow rate ranging from 0 to 40 sccm. The surface morphology and crystallinity were analyzed by field emission scanning electron microscopy (FESEM) and X-Ray Diffractometer (XRD) respectively. The average thickness and deposition rate decreases with an increase of oxygen content. The grain size was measured by FESEM and it was found that it is also decreasing with the increased of oxygen flow rate. The films grown with 10 sccm oxygen shows the highest (002) peak however it is expected that the sample deposited with 40 sccm oxygen exhibit the highest sensitivity toward NH3 gas due to the highest surface to volume ratio.

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