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TitleCharacteristics of cementitlous paste for use in deep borehole disposal of spent fuel and high level wasteforms
Publication TypeConference Paper
Year of Publication2015
AuthorsCollier, N.C., Travis K.P., Gibb F.G.F., and Milestone N.B.
Conference NameMaterials Research Society Symposium Proceedings
Date Published2015
KeywordsCements, Deep boreholes, Fluidity, Geothermal wells, Grouting, Hardened cement paste, High level waste, High temperature and pressure, Mortar, Oil well cementing, Oil wells, Radioactive waste disposal, Radioactive wastes, Sodium, Sodium gluconate, Spent nuclear fuels, Waste disposal, Waste management, Waste package, Well technology
AbstractDeep borehole disposal (or DBD) is now seen as a viable alternative to the (comparatively shallow) geologically repository concept for disposal of high level waste and spent nuclear fuel. Based on existing oil and geothermal well technologies, we report details of investigations into cementitious grouts as sealing/support matrices (SSMs) for waste disposal scenarios in the DBD process where temperatures at the waste package surface do not exceed -190 C. Grouts based on Class G oil well cements, partially replaced with silica flour, are being developed, and the use of retarding admixtures is being investigated experimentally. Sodium gluconate appears to provide sufficient retardation and setting characteristics to be considered for this application and also provides an increase in grout fluidity. The quantity of sodium gluconate required in the grout to ensure fluidity for 4 hours at 90, 120 and 140 C is 0.05, 0.25 and 0.25 % by weight of cement respectively. A phosphonate admixture only appears to provide desirable retardation properties at 90 C. The presence of either retarder does not affect the composition of the hardened cement paste over 14 days curing and the phases formed are durable under conditions of high temperature and pressure. © 2015 Materials Research Society.
DOI10.1557/opl.2015.314Conference Paper

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