Evaluation of assembled organics liquids incorpo-ration in geopolymer matrix: case of viscous oils and greases

International audienceThe nuclear industry produces various types of waste due to its activities (production, opera-tion, decommissioning). For the main part of them, treatment solutions exist, but for others, there is no disposal route and they are stored waiting for a sustainable solution, which includes organic liquids. Currently, incineration is the preferred way to deal with oils and organics liq-uids. However, for this type of process, the waste must satisfy some criteria such as limited alpha/beta activity, fluidity and low concentrations of halogens, sulphur and heavy metals. High viscosity oils and fats represent a small percentage of organic waste without reference treatment. Due to their radioactivity, little information on their chemical composition and rheo-logical properties is available. Our study focuses on the direct immobilization of viscous oils and greases in a geopolymer matrix. In order to incorporate these organic liquids into the material, they must first be made suitable for the GEOIL processing route. The method selected is the assembly of these vis-cous oils and greases with low viscosity organic liquids. Two organic liquids were studied, dodecane and a mixture of tributyl-phosphate (TBP)/dodécane (30/70%Vol.)The second one is currently considered a waste. Its use would allow the elimination of two wastes into a single process. Our research presents the method used, the rheology of viscous oils and greases, the as-sembly rates used, the mechanical strengths of the composites, but also the microstructure and durability of these materials. The first results show a possible incorporation of viscous oils and greases previously assembled with the solvents investigated

Evaluation of assembled organics liquids incorpo-ration in geopolymer matrix: case of viscous oils and greases

International audienceThe nuclear industry produces various types of waste due to its activities (production, opera-tion, decommissioning). For the main part of them, treatment solutions exist, but for others, there is no disposal route and they are stored waiting for a sustainable solution, which includes organic liquids. Currently, incineration is the preferred way to deal with oils and organics liq-uids. However, for this type of process, the waste must satisfy some criteria such as limited alpha/beta activity, fluidity and low concentrations of halogens, sulphur and heavy metals. High viscosity oils and fats represent a small percentage of organic waste without reference treatment. Due to their radioactivity, little information on their chemical composition and rheo-logical properties is available. Our study focuses on the direct immobilization of viscous oils and greases in a geopolymer matrix. In order to incorporate these organic liquids into the material, they must first be made suitable for the GEOIL processing route. The method selected is the assembly of these vis-cous oils and greases with low viscosity organic liquids. Two organic liquids were studied, dodecane and a mixture of tributyl-phosphate (TBP)/dodécane (30/70%Vol.)The second one is currently considered a waste. Its use would allow the elimination of two wastes into a single process. Our research presents the method used, the rheology of viscous oils and greases, the as-sembly rates used, the mechanical strengths of the composites, but also the microstructure and durability of these materials. The first results show a possible incorporation of viscous oils and greases previously assembled with the solvents investigated

Durability of alcali-activated materials in case groundwater intake

International audienceThe development of nuclear power plants around the world with an originally planned lifetime of 25 to 30 years has not led to a sustainable waste management solution within this time period. In specific accident situations, cement matrix has been used as a blocking material to prevent radionuclide release to the environment. One of the problems of this type of disposal is the development of hydrothermal conditions. Hydrothermal solutions are created when rain, snow or groundwater penetrates the concrete mass and comes into contact with the waste. In the worst case, depending on the physico-chemical nature of the groundwater, there may be a release of radio-elements into the environment. This release is dependent on the ability of penetration of water into the material, which is controlled by the porosity of the material. Our study focuses on the durability of alkali-activated materials when subjected to groundwa-ter. For this purpose, different materials were investigated: sodium (Na)-geopolymers, potas-sium (K)-geopolymers and an activated blast furnace slag. These materials are used to be in direct contact with specific wastes (due to their physico-chemical compatibility). In case of geological storage, they are placed in structures made of Portland cement (host matrix), so the groundwater will then become enriched with the chemical elements of the host matrix. In our study, different waters and conditions were considered, from typical CEM V cement wa-ter, lime water, carbonated water, and endogenous conditions. The porosity of the materials was studied by thermoporosimetry, BET and mercury porosimetry up to 180 days of contact with the solutions. A phase analysis by X-ray diffraction and mechanical characterization were also performed. The analysis of the results will allow a first evaluation of the durability of materials, the ideal conditioning matrix should be characterized by a low porosity, a low pore network and a suffi-cient mechanical strength, these properties should be maintained in the future for waste con-tainment..

Durability of alcali-activated materials in case groundwater intake

International audienceThe development of nuclear power plants around the world with an originally planned lifetime of 25 to 30 years has not led to a sustainable waste management solution within this time period. In specific accident situations, cement matrix has been used as a blocking material to prevent radionuclide release to the environment. One of the problems of this type of disposal is the development of hydrothermal conditions. Hydrothermal solutions are created when rain, snow or groundwater penetrates the concrete mass and comes into contact with the waste. In the worst case, depending on the physico-chemical nature of the groundwater, there may be a release of radio-elements into the environment. This release is dependent on the ability of penetration of water into the material, which is controlled by the porosity of the material. Our study focuses on the durability of alkali-activated materials when subjected to groundwa-ter. For this purpose, different materials were investigated: sodium (Na)-geopolymers, potas-sium (K)-geopolymers and an activated blast furnace slag. These materials are used to be in direct contact with specific wastes (due to their physico-chemical compatibility). In case of geological storage, they are placed in structures made of Portland cement (host matrix), so the groundwater will then become enriched with the chemical elements of the host matrix. In our study, different waters and conditions were considered, from typical CEM V cement wa-ter, lime water, carbonated water, and endogenous conditions. The porosity of the materials was studied by thermoporosimetry, BET and mercury porosimetry up to 180 days of contact with the solutions. A phase analysis by X-ray diffraction and mechanical characterization were also performed. The analysis of the results will allow a first evaluation of the durability of materials, the ideal conditioning matrix should be characterized by a low porosity, a low pore network and a suffi-cient mechanical strength, these properties should be maintained in the future for waste con-tainment..

Preservation of genetic diversity in restocking of the sea cucumber Holothuria scabra investigated by allozyme electrophoresis

Population genetics analyses should be considered when releasing hatchery-produced juveniles of the sea cucumber Holothuria scabra when spawners from nonlocal populations are used. In New Caledonia, within-region genetic heterogeneity of H. scabra populations (examined through allozyme electrophoresis of 258 animals) indicated high gene flow between nine sites and FST values did not deviate significantly from zero. However, exact tests indicated that populations at two sites with limited water exchange in the southern location were significantly different from populations at three other locations on the west coast. Inclusion of H. scabra sampled in Bali (n = 90) and Knocker Bay, Australia (n = 47), and comparisons with existing data from the west Pacific (Torres Strait, Solomon Islands, Upstart Bay, Hervey Bay) showed that populations were significantly different (using exact tests) and samples partitioned distinctly using unweighted pair group method with arithmetic mean clustering. Rogers\u27 genetic distance values between populations were significantly related to geographic distances, showing a pattern of isolation by distance. The rapid increase in genetic distance over the first few hundred kilometres supports the view that the spatial extent of any translocation needs to be carefully considered on the basis of knowledge of variation in allele frequencies within the target area