Fra forskningen

Fra forskningen: Chemical Speciation of Long-Lived Radionuclides in the Environment Risø 2008: Plutonium er mere mobilt i cement end i jord og aflejringer, hvilket betyder, der skal ofres særlig opmærksomhed på det ved deponering af radioaktivt affald fra dekommissioneringen:

"The developed method have been successfully used for the investigation of the environmental behaviours of radionuclides. A number of significant investigations have been completed, they are summarized below: (1) The speciation of Pu isotopes in radioactive concrete from the decommissioning of Danish nuclear reactor DK2 was observed to be very much different with those in environmental samples such as soil and sediment, Pu in the concrete is more mobile than that in soil and sediment, which means that a specially attention should be given during the repository of such nuclear waste." (p.48)

Se også Safety in the Final Disposal of Radioactive Waste bl.a. side 38, 1997:

3.3.2 Effects caused by the characteristics of the waste form


Although the basic design philosophy of a waste repository presumes that the waste is either not actively reacting chemically or physically with its surrounding environment or is converted into as stable as possible a chemical and physical form, there are a number of less obvious effects. For example, the slow penetration of moisture into the canister can initiate the dissolving or leaching of the waste material and thereby change the chemical characteristics of the pore solution in the solidification matrix (bitumen or concrete). The corrosion of metal pieces could cause gas formation (hydrogen). In the case of metal wastes, a galvanic reaction might occur between the waste form and the engineered barriers. On the other hand, the presence of corroding inactive metal in the repository could diminish the solubility of metallic radioisotopes such as nickel. The presence of cementitious materials will normally ensure strongly alkaline pore solutions over long periods. However, for wastes containing organic material, such as cellulose, biological degradation may cause gas formation (carbon dioxide) which reacts with the ce- ment producing less alkaline conditions so that the solubility of waste products and radionuclides is enhanced. Colloids or complexing agents may also be produced resulting in increased migration rates in the geosphere. By comparison, inorganic complexing agents are, in most cases, less important. The strength of non-desirable interactions and direct contacts can be avoided or suppressed by the presence of engineered barriers.


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