Saturation buffer materials

We have developed and improved the numerical code THAMES to predict and assess the coupled THM behaviour in and around the EBS of the geological disposal of high-level radioactive waste. THAMES is a finite element code for analysis of coupled thermal, hydraulic and mechanical behaviour of a saturated-unsaturated medium. Then, we applied THAMES to calculate this task of the DECOVALEX III. In this task, the evolutions and the distributions of stress, relative humidity and temperature at the specified points in bentonite buffer material are required. 

The basic THM properties of the buffer material were determined by laboratory tests. These properties Include saturated permeability, thermal... 

Some experimental studies are on-going by INC to build the database for the interaction from chemical process to other processes, such as permeability and swelling properties of buffer material saturated by saline water and of buffer material reacted by cement. In the near future, we will introduce these databases to this research. 

In a HLW repository, the coupled thermo -hydro -mechanical and chemical (T-H-M-C) processes will occur, involving the interactive processes among radioactive decay heat of the vitrified waste (thermal processes), infiltration of groundwater (hydrological processes), swelling pressure of buffer material due to saturation (mechanical processes) and chemical evolution of buffer material and porewater (chemical processes). 

Properties of the medium, initial condition and a boundary condition for thermal process, hydrological process, mass transport and geochemistry are shown in the Table 2. Temperature is fixed at 80°C in the inner boundary of buffer material and the outer boundary of hard rock is assumed adiabatic condition. And the buffer material is unsaturated in initial condition on the other hand hard rock is saturated in initial condition. 

Figure 11, 12, 13 and 14 show the result of the temperature, saturation, pH and concentration of Ca(aq) in buffer material and hard rock, respectively. In these figures, results at 1 year and 10 years are shown and vertical line at x= 0.7 m shows the buffer material / hard rock boundary. As shown in Figure 11, 12, 13 and 14, the results at 1 year is the stage of heat conduction from the inner boundary of buffer material to the outer boundary of hard rock and groundwater infiltration into buffer material from hard rock. And pH and... 

During the resaturation process of the buffer material, the swelling pressure in unsaturated condition is important, though the model explained in the previous section is limited to the saturated condition. In this section, a new equation is proposed to treat swelling pressure in the unsaturated condition. 

Sa.tura.tion Index. Materials of constmction used in pools are subject to the corrosive effects of water, eg, iron and copper equipment can corrode whereas concrete and plaster can undergo dissolution, ie, etching. The corrosion rate of metallic surfaces has been shown to be a function of the concentrations of Cl ,, dissolved O2, alkalinity, and Ca hardness as well as buffer intensity, time, and the calcium carbonate saturation index (35). 

Enzyme Production and Isolation. The production and isolation of veratryl alcohol oxidase (VAO) was described earlier (25). Laccase produced from the same 12-day culture (8 litres) was isolated from the supernatant by precipitation at 0°C with ammonium sulfate (80% saturation). The precipitate was suspended in 0.05 M Na acetate buffer, pH 5.0 and dialysed overnight against 4 litres of buffer. The soluble material was concentrated by ultrafiltration (Amicon PM10) to about 60 mL and applied to a DEAE-Bio-gel A column (2.5 cm x 35 cm). The column was washed with 20 mL of the same buffer, then eluted with a linear gradient from 0 to 0.6 M NaCl (total volume 550 mL). Fractions were monitored for VAO and laccase activity as described below. 

Examination of the absorption spectra of the new polysilane materials reveals a number of interesting features (14). As shown in Table III, simple alkyl substituted polymers show absorption maxima around 300-310 nm. Aryl substitution directly on the silicon backbone, however, results in a strong bathochromic shift to 335-345 nm. It is noteworthy that 4, which has a pendant aromatic side group that is buffered from the backbone by a saturated spacer atom, absorbs in the same region as the peralkyl derivatives. This red shift for the silane polymers with aromatic substituents directly bonded to the backbone is reminiscent of a similar observation for phenyl substituted and terminate silicon catenates relative to the corresponding permethyl derivatives... 

Extraction with MeOH, three elutions through pH 7-buffered Amberlite IRC-50 Plus cation-exchange column, two elutions through pH 4.25-buffcrcd column of the same material, elution with MeOH-HCl, evaporation at 65°C, addition of saturated NaHCO,-McOH, derivatization with DNS. 

Zone electrophoresis is normally carried out horizontally in a suitable medium such as paper, polyacrylamide gel, starch gel or cellulose acetate. The sample components can be completely separated and quantitatively and qualitatively identified in much lower quantities than by the moving-boundary method. The procedure consists of saturating the support material with a buffer solution. The ends of the strip of support are immersed in separate reservoirs of buffer solution to maintain the saturation. The sample is then applied as a narrow band near one end of the support strip. A voltage potential is created down the length of the strip causing the sample components to ionize and then migrate at a rate dependent on their charge, molecular size and interactions with the support medium. When the process is complete, the strip is removed and developed for examination of the separated components. Densitometry is normally used for quantitation of the bands after suitable color development. 

In the case of carrier electrophoresis, a sheet of paper, starch, polyacrylamide or agarose gel or similar materials, where the respective solid phase is saturated with buffer solution, are placed between the electrodes in order to generate a homogeneous, rectified electrical field. The mixture of substances to be separated is supplied as a single spot and the individual components are then separated in the course of time. Carrier electrophoresis is therefore a discontinuous separation process. 

Materials. All monomers were of commercial quality vinyl chloride (VCM), vinyl acetate and VeoVa 10. The latter is a vinyl ester of a saturated monocarboxylic acid with a highly branched structure containing 10 carbon atoms. This monomer is produced by Shell Chemicals. The emulsifier, sodium dodecyl sulphate (SDS), was the commercial material Berol 474 from Berol Kemi, Sweden. NapS 0o supplied by Noury Van der Lande, was used as initiator. The NaHCOq used as buffer and for adjustment of the electrolyte concentration, was Merck p.a. grade. 

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