Nuclear waste laboratory studies

Future improvements in the application of laboratory dissolution data to natural systems will come not (only) from additional work on laboratory kinetics, but will also depend heavily on much more comprehensive studies of surface area distribution, evolution, and accessibility to attack by fluids in natural systems, and by improved understanding of thermodynamic properties of natural fluids. Only in this way will laboratory kinetic data contribute to solving environmental problems such as nuclear waste disposal and evaluating the impact of acid deposition. 

Byers, C. D., Jercinovic, M. J. Ewing, R. C. 1987b. A study of natural glass analogues as applied to alteration of nuclear waste glass. Report no. NUREG/CR-4842 ANL-86-46, Argonne National Laboratory, 150 p. 

There are inherent scale limitations in the time and space dimensions covered by laboratory studies. The applicability of the near field geochemical models derived from laboratory observations have to be applied to long-term, large-scale situations like the ones involved in the safety assessment of nuclear waste repositories. Hence, there is a need to test the models developed from laboratory investigations in field situations that are related to the ones to be encountered in repository systems. 

Studies of Nuclear-Waste Migration in Geologic Media," p. 34, M. G. Seitz, P. G. Rickert, S. M. Fried, A. M. Friedman, and M. J. Steindler, Argonne National Laboratory Report ANL-78-8, 1978. 

The behaviour of technetium in the geosphere is of particular importance in nuclear fuel waste management studies because this man-made element has a long half-life and, under ambient conditions in the laboratory, is not readily sorbed on geologic materials. 

Apps, J. et al. "Geohydrological Studies for Nuclear Waste Isolation at the Hanford Reservation, v. 2", Report No. LBL-8764 Lawrence Berkeley Laboratory, Univ. California Berkeley, California, 1979. 

BinsteadN (1998) EXCURV98 Program. CLRC Daresbuiy Laboratory, Warrington, UK Biwer BM, Soderholm L, Greegor RB, Lytle FW (1997) Uranium speciation in glass corrosion layers an XAFS study. Mat Res Soc Symp Proc 465(Scientific Basis for Nuclear Waste Management XX) 229-236... 

In this section, an application of the proposed models is presented. The case studied here is in connection with the future construction of an underground research laboratory for nuclear waste disposal in a claystone formation. The main purpose is to evaluate the desaturation-resaturation process around the excavation during the excavation and the consolidation phases with different rheological laws. Special attention is given to the dilatancy phenomenon that influences the saturation. 

NOx (typically 1-3%), present in the stack gas of nuclear waste process plants, is removed in die WINCO Process by two primary reactors to 300-1000 ppm by selective catalytic reduction (SCR) with NH3 over a commercial zeolite catalyst at 300-500°C followed by reduction to low ppm levels in a third cleanup reactor. This study involved laboratory tests on advanced SCR zeolite catalysts, NC-301, ZNX, and Cu-ZSM-5, for the primary SCR reactors over a range of anticipated process conditions using gas mixtures containing 500-5000 ppm NO+NO2, 500-5000 ppm NH3, 1-2% CO, 14% O2, and 20% steam in He. All three catalysts have acceptable levels of performance, i.e. selectively reduce >80% the NOx with NH3 to N2 over the temperature range of 400-500°C at a space velocity of 30,000 h- The Cu-ZSM-5 catalyst is the most active and selective catalyst converting >95% NOx d NH3 (at 500 - 5000 ppm of each) to N2. 

In a study of insect-plant relationships at Oak Ridge National Laboratory, Crossley (1963) utilized a field nuclear waste site containing Cs. Chrysomela knabi beetle larvae were collected on leaves from willow trees (Salix nigra) growing on White Oak Lake bed. This lake was formerly a low-level waste disposal site at the laboratory, and the sediments contained various radionuclides, including Cs. Consequently, the leaves of the willow tree contained Cs... 

The literature on SCM largely describes the results of well controlled laboratory investigations of the adsorption of ions by a variety of mineral phases (Davis Kent, 1990). Most of these studies have been undertaken by aquatic scientists interested in developing a thermodynamic understanding of the coordinative properties of mineral surface functional groups. Such studies can benefit performance assessment modeling for nuclear waste disposal, because the chemical and physical principles that have been developed for individual mineral phases can guide studies of natural materials (Davis et al., 1998 Dzombak Morel, 1990). 

The reaction proces.ses can be described by a combination of results from leach tests and SIMS. The nominal composition and leach rates (g in - d" ) of a glass formulation, PNL 76-68 (Pacific North-West Laboratories), used as the. standard high-level nuclear waste glass matrix [4], are shown in Table 4. The definition of leach rate u.sed normalizes the loss (in g) to the proportion of that element in the nominal bulk composition. It will be seen that the leach rates for Cs, Na, Mo, Si and B exceeded the overall rate of mass loss from the gla.ss surface, whereas the elements Fe, Zn and Ti did not show significant loss to solution under these conditions. There were also several elements, e.g.. Ca. Ba, Cd and Sr, that were neither rapidly leached nor apparently retained in the surface layers. Studies described in the above-mentioned reviews, using XPS, FTIR, SIMS, SEM and dissolution rates, have established clearly that the primary reaction occurring in solution is the bond-breaking attack by OH at Si (or Al and... 

Landstrom, O., Klockars, C. E., Persson, O. et al. 1982. A comparison of in situ radionuclide migration studies in the Studsvik area and laboratory measurements. In Lutze, W. (ed.) Scientific Basis for Nuclear Waste Management, V. North-Holland, Amsterdam, 697-706. 

PiRHONEN, V. PiTKANEN, P. 1991. Redox capacity of crystalline rocks. Laboratory studies under 100 bar oxygen gas pressure. SKB Technical Report TR 91-55. Swedish Nuclear Fuel and Waste Management Co., Stockholm. 

Alexander, W. R., Gautschi, A. Zuidema, P. 1998. Thorough testing of performance assessment models the necessary integration of in situ experiments, natural analogue studies and laboratory work. Scientific Basis for Nuclear Waste Management, XXI, 1013-1014. 

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