Natural analogue studies

Smellie JAT, Stuckless JS (1985) Element mobility studies of two drill-cores from the Gotemar granite (Krakemala test site), southeast Sweden. Chem Geol 51 55-78 Smellie JAT, Karlsson F, Alexander WR (1997) Natural analogue studies present status and performance assessment implications. J Contam Hydrol 26 3-17... 

Suksi J, Ruskeeniemi T, Rasilainen K (1992) Matrix diffusion- evidences from natural analogue studies at Palmottu in SW Finland. Radiochim Acta 58/59 385-393... 

Miller, W., Hooker, P. Richardson, P. 2003. Natural analogue studies Their application to a repository safety case. Proceedings of the 10th International High-level Radioactive Waste Management Conference (IHLRWM), March 30 to April 3 2003, Las Vegas. 

Petit, J. C. 1992. Reasoning by analogy. Rational foundation of natural analogue studies. Applied Geochemistry, S.I., 1, 9-14. 

A key problem in the present natural analogue study is the distinction between chemical variations related to trace element migration during basalt alteration and variations due to magmatic fractionation and other syn-intrusive processes. The detailed evaluation of the available data has shown that the chemical and isotopic composition of the HC1 residues is largely controlled by fractional crystallization and syn-intrusive assimilation of salt. In contrast, the chemical composition of the leachates is strongly modified by post-intrusive alteration (Steinmann et al. 1999). 

Bruno, J Duro, L. Grive, M. 2002. The applicability of thermodynamic geochemical models to simulate trace element behaviour in natural waters. Lessons learned from natural analogue studies. Chemical Geology, 190, 371-393. 

Ivanovich, M. et al., Natural analogue study of the distribution of uranium series radionuclides between the colloid and solute phases in the hydrogeological system of the Koongarra uranium deposit, Australia, United Kingdom Atomic Energy Authority Doc. No. AERE-R 12975, Oxfordshire, U.K., Jan. 1988. 

Ivanovich M., Duerden P., Payne T., Nightingale T., Long-worth G., Wilkins M.A., Hasler S. E., Edgehill R. B., Cockayne D. J., and Davey B. G. (1988) Natural analogue study of the distribution of uranium series radionuclides between colloid and solute phases in hydrological systems. DOE report AERE-R. 12975/DOE/RW/88.076. 

McKinley 1. G. and Alexander J. L. (1993) Assessment of radionuclide retardation uses and abuses of natural analogue studies. J. Contamin. Hydrol. 13, 727-732. 

Read D., Hooker P. J., Ivanovich M., and Milodowski A. E. (1991) A natural analogue study of an abandoned uranium mine in Cornwall, England. Radiochim. Acta 52/53, 349-356. 

Based on the leaching data [40,69,83] as well as data on radiation resistance of fast neutron irradiated [84-85] and actinide-doped Synrocs [86-88], as well as individual synthetic phases and their natural analogues study [14-18,89-91] zirconolite- and pyrochlore-based ceramics have been proposed for immobilization of excess plutonium and the other actinides. Moreover, additional phases, which were not part of the Synroc formulation, have been considered because of their chemical durability and radiation resistance (e.g., murataite, zircon, garnet, monazite, britholite). Of particular interest are the zirconate pyrochlores, many of which are extremely radiation resistant [8,92]. Zirconolite-based ceramics. Zirconolite, ideally CaZrTi207, is a major actinide host phase in the Synroc-type ceramics. Study of natural and synthetic samples... 

Figure 13.11 Eh-pH diagram showing measured Eh and pH values in groundwaters in the Palmottu uranium deposit. Finland, The diagram is drawn for Q (total carbonate) = 2 x 10" M and 10 M SOI , with SU = 10 M at the U307(s) boundary. This solid (equivalent to UO3 33(5)) is considered a possible control on dissolved U concentrations. UC, UDC and UTC are defined in Fig. 13.9. Modified from Ahonen et al., Uranium mineral-ground-water equilibration at the Palmottu natural analogue study site, Finland. Mat. Res. Soc. Symp, Proc. 294 497-504. Copyright 1993 by Materials Research Society. Used by permission.

Ahonen, L., H. Ervanne, T, Ruskf.eniemi, T. Jaakkola, and R. Blomqvist. 1993. Uranium mineral-groundwater equilibration at the Palmottu natural analogue study site, Finland. Mat. Res. Soc. symp. proc. 294, pp. 497-504. 

Natural Analogue Studies in the Geological Disposal of Radioactive Wastes... 

Abstract In the near-field of a high-level radioactive waste (HLW) repository, the coupled thermo -hydro -mechanical and chemical (T-H-M-C) processes will occur. Observation periods by laboratory and in-situ experiments are very short and information by natural analogue studies is very limited, so numerical experiments are the only available approach to predict the near-field long-term evolution. We have initiated a research on the coupled T-H-M-C processes and are trying to carry out numerical experiments on the coupled T-H-M-C processes in order to predict the near-field long-term evolution. This paper presents our current status and future activities on the research for numerical experiments on the coupled T-H-M-C processes. 

Closer interaction between natural analogue studies, focused laboratory experiments and modelling work is required ... 

To demonstrate and gain confidence in the long term behaviour of the disposal system, predictive models are developed and applied in performance assessments, covering not only the behaviour of individual components of the system but also the overall multi-barrier system. Many elements of performance assessments can be modelled today. Extensive international programmes and cooperation in this field are underway to improve performance assessment methods (e.g. scenario development, sensitivity/uncertainty analysis...) and with a view to "validate" performance assessment models. In this latter context, Natural Analogue studies and results from in-situ experiments have a great potential for model development and testing purposes. 

Fig. 6.23 Diagrammatic view of a generic uranium ore body showing the principal processes of interest in natural analogue studies In this geological environment (Miller et al. 1994)...

In addition to the far- and near-field studies on natural analogues mentioned above, the studies on radionuclide migration mechanisms (e.g., solubility, specia-tion, sorption, adsorption, ion exchange, precipitation, matrix diffusion, colloid, redox front, biological activity, gas generation) are also regarded as the natural analogue studies. 

Marini L (2007) Geological sequestration of carbon dioxide. Elsevier, New York Miller W, Alexander R, Chapman N, Mckinley I, Smellie J (1994) Natural analogue studies in the geological disposal of radioactive wastes. Elsevier, Amsterdam Nishimura M (1991) Environmental chemistry. Syokabo, Tokyo (in Japanese)... 

Duijvestijn 1994) are extremely conservative and a more realistic estimate of the canister lifetime (which is well supported by extensive natural analogue studies, discussed below) would be about 10 years. 

The fuel dissolution process is very dependent on redox conditions which are, in turn, influenced by the extent of radiolysis of water. Radiolysis is dominated by the o-particle flux and is very sensitive to the available surface of fuel, the geometric distribution of water present, the burn-up of the fuel and the time since emplacement. The chemistry of the water, which critically affects the extent and rate of formation of alteration products, is also of importance. Although there is an extensive database of laboratory studies, there is still some controversy on the magnitude of net dissolution rates under expected conditions. Natural analogue studies of uranium ore bodies indicate that dissolution rates would be at the lower end of those derived from laboratory studies (see below). 

One potential weakness in the above approach is that the effects of interfaces (pH/Eh) and heterogeneities in the EBS are ignored. This has been tackled by McKinley et al. (1997) who noted that their more thorough analysis ... gives a more realistic evaluation of possible microbial perturbations (of the HLW nearfield) which indicate that the net effect of such populations may be positive, leading to decreased radionuclide release (due to uptake in and around the fronts). The critical assumption, however, is that microbes cannot utilise the very low energy density of the reaction between steel and water. The conclusion that microbial activity could contribute to radionuclide retention is well supported by natural analogue studies which have shown that trace element traps, such as redox fronts or haloes, are established by microbially catalysed reactions (e.g. West et al. 1992 Hoftnann 1998). 

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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