FR2948224A1 - Method for immobilizing solid or liquid form nuclear waste e.g. organic nuclear waste, involves preparing base, and treating base for transforming inactivated mineral material with predetermined texture to obtain mineral composition - Google Patents

Abstract

The method involves preparing base comprising predetermined quantity of mineral material by synthesizing part of living structure selected from plant kingdom, animal kingdom and/or microorganisms. The base is treated for transforming the inactivated mineral material with predetermined texture to obtain mineral composition, where the mineral composition has 50 percent to 80 percent of calcium carbonate and 10 to 30 percent of silicon.

Description

Method of immobilizing nuclear waste with a biomaterial

The present invention relates to a process for immobilizing nuclear waste by a matrix based on a mineral composition obtained by preparing a base comprising a predetermined quantity of a mineral material synthesized by at least one part of living structure chosen from the plant, animal and / or microorganism kingdoms. Radioactive or nuclear waste is a radioactive material for which no use is planned and the dispersion of which in the environment is not permitted. Radioactive waste covers a wide variety of substances that differ in particular in their activity and their half-life, but also in their state (solid, liquid, gaseous) and their chemical composition. Disposal of waste, particularly nuclear waste, is a major environmental problem. Nuclear waste (liquid or solid) can be contaminated on the surface and in bulk.

The waste of the nuclear industry is specific, on the one hand their toxicity decreases with time, and on the other hand their diversity requires packaging methods adapted to volumes and their activity. There are many methods for conditioning waste in the nuclear industry. Two main modes of packaging are used for nuclear waste, compaction or blockage. Compacting is a primary packaging mode where compacted products must be packaged in a package.

Blocking or immobilization of waste is a technique commonly used in the nuclear industry where cement is used to immobilize nuclear waste within containers or as a packaging matrix for coating nuclear waste. In addition to its use for blocking massive solid waste in containers, cementing is also used to coat waste in solution or in powder form, for example evaporation residues, chemical treatment sludges or ion exchange resins. . Whatever the level of contamination of nuclear waste, they must be stored in safe facilities for quite long periods, for example several hundred years. During the storage period, it is necessary to guarantee the integrity of the storage package, in particular the packaging and the content of the waste and the matrix. These waste packages comply with strict criteria, in particular with regard to the matrix. The content must be sufficiently stable and not subject to dissemination related to storage conditions. Blocking with a cement is a low cost process and easy to implement, but it is not without drawbacks. Interactions between the constituents of some nuclear waste and the cement matrix can lead to swelling and cracking of the package, reducing its durability. Cementation is the most used technique for solid waste. The main reasons for this choice are the abundance of raw materials, the density of the material (biological protection), the mechanical resistance, the good knowledge of its long-term behavior, the robustness of the process and the simplicity of its implementation. . The previously compacted or bulk waste is usually placed in a basket, itself deposited in a metal container or concrete; they are then immobilized by cement, responsible for limiting the risk of diffusion of the radioelements to the outside, and thus form a heterogeneous coating. However, cementation does not guarantee the durability of the packages for some chemically charged nuclear waste (sulphates, etc.) or reagents or containing organic matter. Indeed, the cementing process is an exothermic process that may provoke violent reactions when mixing with reactive nuclear waste.

In addition, the cementitious medium has an alkaline pH of the order of 13 to 14 which may not be compatible with certain nuclear waste. Moreover, the blocking of the reactive materials generates gases making it impossible to guarantee the integrity of the packages over long periods, for example periods of at least 300 years. Thus, an object of the present invention is to propose another solution that makes it possible to immobilize nuclear waste that does not have the drawbacks of the solutions of the prior art. The invention thus proposes a process for immobilizing nuclear waste, comprising: a mixing step during which nuclear waste is mixed with a mineral composition and water, a drying step in which the mixture obtained in the mixing step is dried to form an immobilization matrix, wherein the mineral composition is obtained by a manufacturing method comprising the steps of: preparing a base comprising a predetermined amount of a mineral material synthesized by at least a portion of living structure selected from the vegetable, animal and / or microorganism kingdoms; and treating said base to transform it into an inactivated material of predefined texture.

Advantageously, the immobilization method according to the invention makes it possible to immobilize chemically charged nuclear waste and / or reactive metallic nuclear waste and / or organic nuclear waste which can not be immobilized by conventional cementation.

An immobilization method according to the invention may further comprise one or more of the optional features below, considered individually or in any combination possible: the mineral composition is chosen so that, mixed with water, it has a pH of between 11 and 12;

The mineral composition is chosen so that the reaction between said mineral composition and the water is substantially athermic;

the ratio of the mass quantity of the mineral composition and the mass quantity of water is greater than or equal to 6/4 and less than or equal to 85/15; the mineral composition is chosen so that the immobilization matrix has a resistance to compressive stresses greater than or equal to 8 MPa; during the mixing step the sand is added again so that the ratio of the mass quantity of the mineral composition and the mass quantity of sand is greater than or equal to 1.5 and less than or equal to 10; the mixing step comprises: a premixing step during which the mineral composition and water are mixed, a kneading step during which the mixture obtained during the premixing step is kneaded, And an injection step in which the kneaded mixture is injected into a package containing the waste to be immobilized;

The mixing step comprises: a premixing step in which the nuclear waste, the mineral composition and the water are mixed, a kneading step in which the mixture obtained during the step premix is kneaded, and an injection step in which the kneaded mixture is injected into a package for containing the nuclear waste. The mineral composition comprises at least 90% by weight of calcium carbonate; the mass quantity of nuclear waste in the immobilization matrix is greater than or equal to 10% and less than or equal to 80%. The invention will be better understood on reading the description which follows, given solely by way of example. The present invention relates to a method of immobilizing chemically charged or reactive nuclear waste or containing organic material and more particularly those which can not be blocked by hydraulic binders. Advantageously, the process according to the invention makes it possible to achieve the encapsulation of this waste in a homogeneous and durable matrix meeting predefined storage criteria. Among the nuclear waste that can be blocked by the process according to the invention, mention may be made, without this being a limitation, of oils, resins, ion exchange resins (REI), graphite, magnesium uranium, aluminum, bitumen, sludge, brine, borate and sulphate products, sludges or concentrates containing organic matter and mixtures thereof. According to one embodiment of the invention, the immobilization method comprises: a mixing step in the course of which nuclear waste is mixed with a mineral composition and water, a drying step during from which the mixture obtained during the mixing step is dried so as to form an immobilization matrix.

The mixture of the mineral composition and the water allows the mineral composition to achieve a structural arrangement leading to the creation of a three-dimensional network. The realization of this network leads to a setting in mass of the hydrated mineral composition around the nuclear waste which, after a certain drying time, makes it possible to obtain a compact mass composed of the waste and an immobilization matrix. The mineral composition used in the process according to the invention is obtained by a manufacturing process comprising the steps of: preparing a base comprising a predetermined amount of a mineral material synthesized by at least one living structure part selected from the group consisting of Vegetable, animal and / or microorganism; and treating said base to transform it into an inactivated material of predefined texture.

Documents FR9405013, FR9504830, FR9504831, FR9504832 and WO95 / 29250 describe examples of mineral compositions that can be used in the process according to the invention. According to one embodiment of the invention, the mineral composition used in the process according to the invention is a mineral composition obtained by a manufacturing method comprising the steps of: preparing a base comprising a predetermined quantity of a material mineral synthesized by at least a portion of living structure selected from the plant, animal and / or microorganism; and treating said base to transform it into an inactivated material of predefined texture.

For the purposes of the invention "living structure" mineralizing, mineralized or mineralizable, it is necessary to understand any cell structure or cell origin, plant, animal or micro-organic, living and / or resulting from life and / or compounds of biological origin, crystallized or not, such as enzymes, hormones, proteins, DNA. By "inactivated material", it is necessary to understand matter devoid of any biological activity and / or biomineralisator especially of any pathogenic microbiological activity. For the purposes of the invention the term "mineral" should be understood in the broad sense, namely to include in its composition a mineral.

The step of preparing the base may comprise a phase consisting in cultivating the abovementioned living structure during a period and in a medium such that at least one part called "mineral biomass" of said material is then produced or synthesized by this structure.

The treatment step may then comprise a phase of inactivation of the living structure. By inactivation, it is understood to obtain inactivated material, as defined above, from living structure as defined above.

A mixing phase may be performed during one of the steps of the manufacturing process. Preferably, this mixing step is carried out at least partly simultaneously with another phase of the process according to the invention, for example during the inactivation or after the mixing step. The manufacturing process may be carried out with microorganisms and / or cells, of vegetable or animal origin, alone, or in symbiotic or other association, mineralized, mineralizing or mineralizable. The aforesaid living structure may be a plant and / or animal or part of a plant and / or animal such as cell, tissue or organ. In the vegetable kingdom, it will be possible to use as well higher plants, dicotyledonous, monocotyledonous plants, as well as lower thallophytic or microorganic plants. Depending on the case, the selected structure is cultivated in vivo, in soil, on a layer rich in organic matter, by hydroponics, in a petri dish, in a reactor such as fermenter or by battery culture, on feet or fish farming, in particular. The structure can be cultured in a suitable nutrient medium known to those skilled in the art such as Knopli's liquid, Earle's solution, Hanks, "199" medium, Sabouraud's medium, MEM-Eagle's medium or the like. The step of preparing the base may comprise a step of harvesting and / or collecting the aforesaid living structure, and incorporating it into the base in such proportions that such input constitutes at least a portion of the required mineral material. The mineral material thus harvested and / or collected may be of varied nature: carbonated, siliceous, saline, fluorinated, barium, carbonaceous, ferruginous, in the form of, for example, current and / or fossil deposition, concretion. It is then incorporated in the base either during the preparation step, or during the processing step. Fossil and / or other sedimentary rocks such as granite, basalt, pumice or the like may be included in the composition of the final material.

During a possible phase of the manufacturing process, at least one of the abovementioned biomass, base, material and / or mineral material is fragmented during the preparation step, and / or during the treatment step .

The abovementioned fragmentation is at least partially carried out by dislocation using ultrasound and / or physicochemical means, such as addition of additives, irradiation, cryogenic and / or thermal treatment, grinding or pressure variation.

One of the phases of the process may be to develop a suspension of the aforementioned biomass, base or material in a liquid, preferably aqueous for spraying or brushing, for example. This liquid can be used in the composition of one of the abovementioned culture media. It is possible to incorporate during a phase of the process, at least one of the culture medium, the biomass, the material, the base and the mineral material, a coloring substance of predetermined shade.

An optional phase of the preparation and / or treatment step comprises incorporating into at least one of the biomass, the medium, the material, the base and the mineral material, a cohesion and / or texture agent. This cohesion agent and / or texture is preferably metal such as calcium, magnesium, silicon, barium, sodium, fluorine, aluminum, iron, manganese, zinc, or organic such as collagen, mucopolysaccharide and / or polycellulosic compound. Advantageously, the proportions and the composition of the aforementioned texture agent are chosen so that the final material has a predetermined hardness and / or elasticity.

Furthermore, the manufacturing process may comprise a phase of total or partial dehydration of the inactivation salt (s) comprising the abovementioned base and / or mineral material.

This dehydration phase may be at least partially carried out by filtration, centrifugation, heat treatment and / or cryogenics. It is possible according to the manufacturing process, that the phases of inactivation, dehydration and fragmentation, are at least partially performed simultaneously. During one of the phases or steps of the manufacturing process, an additive, for example foaming, fibrous, agglomerating, insulating, flame retardant or the like may be incorporated in the base and / or the aforementioned mineral material. The following classification gives non-limiting examples of structures that can be selected for the application of the invention: a) Among the Dicotyledons:

- The cells of the order of Daucales, family Araliaceae, genus Hedera including Hedera helix; The cells of the order Arales, genus Rhaphidophora, species Syngonium podophyllum (Schott), "Albolineatum", species Syngonium auritum syn. Philodendron trifolium and Syngonium hastifolium species; - Cells of the order Solanales, family Bignoniaceae, species Catalpa bignonioidées where it is calcium oxalate in octahedral form, "urchins", abundant in the cells of the petioles, for example.

Any plant cell, even that which is hardly symbiotic, is susceptible, by the process just stated, to be mineralized and / or super-mineralized if it is brought into contact with such microorganisms.

This is the case of the above-mentioned cells, but also of all the plant cells resulting for example from brush in the form of chips, sawdust, which by this process petrify or become tuffous and / or travertineous stone. (b) Among the Monocotyledons:

- The cells of the order Pandarales including those of the family of the Typhacées; - Grass cells, including those of Lemnaceae,

c) Among the ferns:

The epidermis in Equisetum arvense (Common horsetail) is the theater of silica mineral productions often considered as concretions resulting from epidermal membrane secretions while there are involved bacteria on the periphery and / or in the cells of Equisetum arvense. These explain the deposits of intra- and / or extracellular silica. The siliceous cover of the sterile aerial shoot of Equisetum arvense and the deposits of opaline silica encrusting the epidermis of its various aerial organs is related to the presence and symbiotic participation of bacteria. These are bacilli 0.4 to 0.7 microns long and 0.1 microns thick. These mineralising bacilli cause progressive external impaction of the cells concerned as the development of bacterial veils. These successive veils cause a homogeneous and stratified siliceous covering.

d) Among Algae: Biomineral masses resulting from the multiplication and accumulation of algae frustules in a natural or industrial way are applicable to the invention. For example: - Rhodophyceae with mainly Nemalionales, Solenoporaceae and Corallinaceae (including Lithothamnium, Melobésiés, - Chlorophycées with Siphonales (including Codiacées including Halimeda) and Dacycladales (including 15 dacycladacées including Acétabularia) Charophyceae with Characeae including Cladophora and Vaucheria Schizophyceae with Porostromata and Spongiostroma of which Rivularia, Oscillatoria, Phormidium, Chroococcus and Gleocapsa are suitable for selection.

e) Lichens:

The biomineral mass may also result from the cultivation of a tripartite lichenic plant association. Lichens are composite plant associations. The so-called reciprocal benefit association consists of a fungus, an alga and mineralizing bacteria similar to those mentioned above. These bacteria contribute to complex and pigmented mineral encrustations within the mycelium. The existence of lichenic acid deposits in the form of extracellular and hydrophobic crystals due to the mineralization of lichens by said symbiotic bacteria. The symbiotic bacteria are distinguished from the cyanobacteria sometimes mentioned by their small size and the absence of pigment.

The living structure can therefore be simply the cells of a plant thus physiologically equipped.

f) Among the fungi: The structure of plant origin may be a lower plant selected from fungi and their spores.

g) -Among microorganisms: The living structure may be a micro-organism such as a virus or bacterium including bacillus megatherium, pseudomonas fluorescens, pseudomonas maltophilia, pseudomonas putida, buttauxiella agrestis, rhodococcus, serratia marescens. We can consider the use of a virus as a living structure. The living structure may also be an animal, or part of an animal such as a cell, tissue and / or organ, chosen from invertebrate protozoa or metazoans such as sponges, lamellibranchs and echinoderms or even from vertebrates.

One or more compatible living symbiotic or cooperating structures can be cultivated within the same medium, whether of plant, animal and / or micro-organic origin. The first preparation step is intended to obtain a mineral base, that is to say an intermediate product. Preferably, the step of preparing the base comprises a step of cultivating the abovementioned living structure during a period and in a medium such that at least one part called "mineral biomass" of said material is then produced or synthesized by this structure .

The second step is to treat said base after its demineralization so as to transform it into a deactivated or inactivated mineral material and predefined texture. For example, one or more of the correspondences between the living structures and the minerals and / or the rocks below, can be selected: Cells of Hedera helix correspond to Calcium oxalate / Limestone Cells of Ficus élastica correspond to Calcium carbonate / Limestone Equisetum cells correspond to Silica / Opaline / Silicified wood / Sandstone Grass cells correspond to Silica / Opaline / 20 Silicified wood / Sandstone Typhaceae cells correspond to Silica / Opaline / Silicified wood / Sandstone Ascomycete fungus corresponds to Calcium Dipicolinate / Limestone Pectascinaceae Cells correspond to 25 Calcium Carbonate / Limestone Phthophyseae Algae corresponds to Silica / Diatomite / Rhodophycean Algae corresponds to Calcium Carbonate / Limestone / Travertine Chlorophyceae Algae corresponds to Calcium Carbonate / 30 Calcium / Travertine Cyanophyceae Algae corresponds Calcium carbonate / Limestone / Travertine M ollusque Lamellibranch corresponds to Calcium carbonate / Limestone / Shellfish sandstone

The production of biomass obeys the usual laws of the growth of living structures: it is not necessary to describe here the culture phase with precision. Those skilled in the art will be able to determine, depending on the living structure to be grown, which culture method and which medium can be used with the most success. Thus, it is possible, depending on the type of structure selected, to use one of the processes developed such as in vivo culture, in soil, on a layer rich in organic matter, by hydroponics, in a petri dish, in a reactor such as fermentor or by breeding in battery, on feet or fish farming, in particular. In the case of plants maintaining their integrity, conventional cultivation methods are preferably employed (in soil, greenhouse, hydroponics, etc.). When the abovementioned living structure is a part of a plant such as a cell, tissue or organ, the living structure may originate from a so-called superior monocotyledonous plant, such as water or dicotyledonous Lentils and especially from Daucales, Lianas, Bignoniaceae, Moreae, Comrnaceae, Cactaceae.

For this type of structure which, for example, produces a tuffous and / or travertineous material, it is possible to use the following culture medium: Distilled water 1000 grams Calcium nitrate 0.71 Potassium nitrate 0.568 Magnesium sulphate 0.284 Ammonium phosphate 0.142 Ferric chloride 0.112 Potassium iodide 0.0028 Boric acid 0.0005 Zinc sulphate 0.0005 Manganese sulphate 0.0005 In addition, the structure of vegetable origin may be an alga and in particular Rhodophyceae, chlorophyceae, Charophycée, Schyzophycée, Cyanophycée, Pheophycée and / or a Protophyte, and other media are possible.

The same applies if the living structure is an animal, or part of an animal such as cell, tissue and / or organ, and in particular a protozoa with sandy, carbonate, siliceous or chitinous test, mesoglées of spongiaries with calcareous spicules or silicones, corallary cells, epidermal shell cells, or cells that cause bone structures in vertebrates. The mineral biomasses can be obtained by in vitro culture of the tissue cells and / or organ involved in the mineral biosynthesis of the animal kingdom. It is possible to use, for example, current and / or fossil coralline production to produce specific limestones. The micro-organisms are also abundantly cultivable in commercial industrial fermenters, and in particular tangential filtration ultrafermentors, which make it possible to obtain continuous production.

One or more compatible living structures can be grown in the same medium, possibly with at least one other compatible structure of plant, animal and / or microorganic origin.

The second step is to treat said base after its demineralization so as to transform it into an inactivated mineral material and predefined texture. In the case of biomass production from a living structure, the treatment step then comprises a phase of inactivation of the living structure. This inactivation phase may be carried out by adding at least one salt, such as, for example, magnesium oxide, magnesium sulphate, calcium chloride or barium chloride, preferably in anhydrous form.

The biomass is stabilized, that is, inactivated so that any cellular development is interrupted. Such a result can be obtained by adding in suitable proportions, one or more of the above salts, or substances having similar effects on the living structure retained. In the case of the use of these compounds, the respective proportions (in mass units) of 1 part of magnesium sulphate, 0.5 part of calcium chloride, 0.5 part of barium chloride, 2 parts of magnesium oxide, preferably anhydrous, are acceptable. However, these proportions may vary, especially in a range of 20% to 50%. Other inactivation methods may be employed, alone or in addition, including the use of chemical compounds including fluosilicates or irradiation and elevation at high temperature. A mixing phase may be performed during one of the steps of the manufacturing process. Preferably, this mixing step is carried out at least partly simultaneously with another phase of the process, and in particular during inactivation. Two inactivation phases can be used: one during the production of the product, the other during use, for example during the mixing state of the process according to the invention. The total inactivation of the living structures of the base is then carried out by mixing the biomass and salts mentioned, with a supply of water in equal amounts, to ensure a good mixture thereof. By way of example, the base can be added to the salts mentioned in proportions ranging from 0.5 base per 1 of salts to 4 bases per 1 of salts.

One advantage of the manufacturing process is that the step of preparing the base may comprise a phase of harvesting or collecting either the above-mentioned living structure or the sedimentary mineral material, and incorporating it into the base in proportions such that this input constitutes at least a portion of the required mineral material. It is possible to collect the mineral material in the form of, for example, deposition, actual and / or fossil concretion, and to incorporate it into the base either during the preparation step or during the treatment step. Moreover, the living structure is chosen so that its associated mineral matter contains at least one carbonate, siliceous, selenitic or similar mineralogical constituent. Many other new sources of mineral are usable according to the invention. Desarroting or other agricultural operations (harvests such as haying, harvesting, harvesting and others) generate large quantities of mineralized or mineralizable or mineralising products and capable of over-mineralization (hay, straw, stubble, etc.). Some industrial operations generate waste of plant origin, such as sawdust, which can be mineralized. Cells of relatively rigid plants and particularly those of Lianes are mentioned, for example Syngonium podophyllum, Syngonium auritum syn. Philodendron trifolium and Syngonium hastifolium. Lierres, Figuiers, constitute a potential source of mineral substrates. The same is true for coastal algae deposits such as Maerl. During a possible phase of the manufacturing process, at least one of the abovementioned biomass, base, material and / or mineral matter is fragmented during the preparation step, and possibly during the inactivating treatment step. . For example if during the cultivation of a living structure one obtains mineral and / or stratified stacks, which one can possibly break up for their use within the base. Similarly, if part or all of the mineral material is constituted by fossils or solid waste, as explained above, the blocks in collected masses can be crushed or fragmented. The fragmentation phase is carried out until a determined texture or malleability is obtained. In other words, the purpose of the fragmentation is to obtain a more or less loose material, and preferably with a given particle size. The abovementioned fragmentation is at least partially carried out by dislocation using ultrasound and / or physicochemical means, such as addition of additives, cryogenic and / or thermal treatment, grinding or pressure variation.

In this case, one of the phases of the manufacturing process may be to develop a suspension of the aforementioned biomass or fragmented material in a liquid, preferably aqueous. It is possible to incorporate during a phase of the process, at least one of the culture medium, the biomass, the material, the base and the mineral material. This substance is possibly an element of biomass. A preparation and / or treatment step may consist in incorporating into at least one of the biomass, the medium, the material, the base and the mineral material, a cohesion or texture agent. This agent is preferably a particularly metallic binder such as calcium, magnesium, silicon, barium, sodium, fluorine, aluminum, iron, manganese, zinc, or organic such as collagen, mucopolysaccharide and poly-cellulosic compound. It is already understood that this agent is optionally used as an inactivation compound, in the case of a base comprising a living structure, cultivated or collected.

Advantageously, the proportions and the composition of the above-mentioned cohesion and / or texture agent are chosen so that the final material has a predetermined hardness or elasticity. During one of the phases or steps of the process, an additive, for example foaming, fibrous, agglomerating, insulating, flame retardant or the like may be incorporated in the base and / or in the aforementioned mineral material. Furthermore, the method may comprise a phase of at least partial dehydration of one or more components of the base and / or the aforementioned mineral material.

This dehydration phase can be at least partially carried out by filtering, irradiation, centrifugation, heat treatment and / or cryogenics. It is possible according to the method, that the phases of inactivation, dehydration and fragmentation, are at least partially performed simultaneously. According to one embodiment of the invention, the mineral composition comprises at least 90% limestone. The mineral composition according to the invention can be in the form of a divided solid which after incorporation of a predetermined amount of water and an intimate kneading step leads to a dough known as petrifying mix. The viscosity of the Mix paste is adjustable by adjusting the proportions of mineral composition and water. The production of the blocking matrix is possible after thorough mixing of the mineral composition and water at room temperature. The fluidity of the mixture, the mechanical properties and the setting time depend on the water content. It is adaptable to the nature of the material and makes it possible to block nuclear waste. The drying of Mix paste leads to a homogeneous matrix whose mechanical and chemical characteristics are compatible with the storage of nuclear waste.

For example, the mechanical properties of the immobilization matrix are: a compressive stress greater than or equal to 8 MPa, typically 25 MPa after 30 days; and / or an absence of gassing or bleeding even under load; and / or a dimensional shrinkage equivalent to the cementitious matrices; and / or a good radiation resistance; and / or no change in compressive strength after irradiation of 1300 kGy.

According to one embodiment of the invention, the mixing step comprises: a premixing step during which the mineral composition and the water are mixed, a mixing step during which the mixture obtained during of the premixing step is kneaded, and an injection step in which the kneaded mixture is injected into a package containing the waste to be immobilized.

According to one embodiment of the invention, the mixing step comprises: a premixing step during which the nuclear waste, the mineral composition and the water are mixed, a kneading step in the course of wherein the mixture obtained during the premixing step is kneaded, and an injection step in which the kneaded mixture is injected into a package intended to contain the nuclear waste.

The invention is not limited to the embodiments described and should be interpreted in a nonlimiting manner, and encompassing any equivalent embodiment.

Claims (10)

REVENDICATIONS1. A method of immobilizing nuclear waste material comprising: a mixing step in which nuclear waste is mixed with a mineral composition and water; a drying step in which the mixture obtained at the time of mixing step is dried so as to form an immobilization matrix, characterized in that the mineral composition is obtained by a manufacturing method comprising the steps of: preparing a base comprising a predetermined amount of a synthesized mineral material by at least part of living structure selected from the vegetable, animal and / or microorganism kingdoms; and treating said base so as to convert it into an inactivated material of predefined texture. 2. The process according to claim 1, wherein the mineral composition is selected so that, when mixed with water, it has a pH of between 11 and 12. 3. Method according to one of claims 1 or 2, wherein the mineral composition is chosen so that the reaction between said mineral composition and water is substantially athermic. 4. Process according to any one of the preceding claims, in which the ratio of the mass quantity of the mineral composition and the mass quantity of water is greater than or equal to 6/4 and less than or equal to 85/15. 5. Method according to any one of the preceding claims, wherein the mineral composition is chosen so that the immobilization matrix has a compressive strength resistance greater than or equal to 8 MPa. 6. Method according to any one of the preceding claims, wherein during the sand mixing step is added so that the ratio of the mass quantity of the mineral composition and the mass quantity of sand is greater than or equal to at 1.5 and less than or equal to 10. 7. A process according to any one of the preceding claims wherein the mixing step comprises: a premixing step in which the mineral composition and water are mixed, a mixing step in which mixing obtained during the premixing step is kneaded, and an injection step in which the kneaded mixture is injected into a package containing the waste to be immobilized. 8. A process according to any one of claims 1 to 6, wherein the mixing step comprises: a premixing step in which the nuclear waste, the mineral composition and the water are mixed, a step in which the mixture obtained during the premixing stage is kneaded, and an injection step in which the kneaded mixture is injected into a packaging intended to contain the nuclear waste. 9. A process according to any one of the preceding claims, wherein the mineral composition comprises at least 90% by weight of calcium carbonate. 10. A method according to any one of the preceding claims, wherein the mass quantity of the nuclear waste in the immobilization matrix is greater than or equal to 10% and less than or equal to 80%.