EP2302642A1 - Process for treating solid radioactive material - Google Patents

Abstract

The method involves crushing radioactive solid materials in a range of predetermined granulometry, and mixing the crushed radioactive solid materials with a cementitious self-leveling concrete composition in order to form self-leveling concrete fluid screed (5). The self-leveling concrete fluid screed is injected into an underground cavity (C) in a landfill site, where the landfill site is in direct contact with walls of the underground cavity. Concrete blocks and/or rubble are armed with a steel structure.

Description

The present invention relates to a method of treating radioactive solid materials.

It relates more particularly to a method of treating blocks and / or concrete rubble from the dismantling of buildings exposed to radioactivity and having a mass radioactivity of less than 100 Becquerels per gram (Bq / g).

Radioactive materials with a mass radioactivity of less than 100 Bq / g are so-called very low-activity materials or wastes, ie whose activity level is very close to natural radioactivity, with a mass radioactivity generally between 1 and 100 Bq / g sometimes more for very small volumes. A few decades are enough for their level of activity to reach an average level of a few Bq / g, the residual radioactivity being mainly due to long-lived elements.

• le démantèlement des installations nucléaires arrêtées, telles que les centrales nucléaires, laboratoires d'études, centres de recherches et sites de production de matières radioactives ;
• le démantèlement d'industries classiques (chimie, métallurgie, production d'énergie) dont les procédés de fabrication concentrent la radioactivité naturelle de certains minerais ou emploient des matériaux naturellement radioactifs ; et
• l'assainissement et la réhabilitation de sites anciennement pollués comme certains laboratoires ou installations industrielles.

Waste of very low activity usually comes from the following sources:

• the dismantling of arrested nuclear installations, such as nuclear power plants, research laboratories, research centers and production sites for radioactive materials;
• the dismantling of conventional industries (chemistry, metallurgy, energy production) whose manufacturing processes concentrate the natural radioactivity of certain ores or use naturally radioactive materials; and
• remediation and rehabilitation of formerly polluted sites such as certain laboratories or industrial facilities.

• les déchets minéraux inertes : bétons, gravats, plâtres, terres etc. ;
• les déchets assimilables aux déchets industriels banals, produits par des installations nucléaires, qui sont généralement des plastiques et ferrailles principalement issus des opérations de démolition (charpentes métalliques, structure en acier pour béton armé, gaines, tuyauteries, etc.) ; et
• les déchets assimilables aux déchets dangereux qui sont classiquement gérés en centre de stockage de déchets ultimes.

Waste of very low activity thus consists of materials that have been in contact with radioactive products or have been weakly activated as a result of irradiation with neutrons, and they are classified into three broad categories:

• inert mineral waste: concretes, rubble, plaster, land etc. ;
• waste comparable to ordinary industrial waste, produced by nuclear installations, which are generally plastics and scrap mainly from demolition operations (metal structures, steel structures for reinforced concrete, ducts, pipes, etc.); and
• waste equivalent to hazardous waste, which is conventionally managed as an ultimate waste disposal facility.

Although the radioactivity of very low-level waste is close to natural radioactivity, it is still necessary for reasons of public health and environmental protection to treat this waste, and more particularly to store it while taking precautions. precautions and measures to monitor the evolution of storage sites.

For the treatment of radioactive materials, it is known from the document FR 2 624 410 A1 a method of underground containment of toxic industrial waste in an underground cavity dug by leaching into the salt, which consists in injecting at the bottom of the cavity a buffer liquid, mixing the waste in the form of granules with a hydraulic binder, and injecting the mixture into the cavity below the level of the buffer liquid. However, this process proves to be complex and time-consuming for treating radioactive solid materials of very low activity, in particular because of the different products required for the different steps such as the buffer liquid requiring the use of a halogenated solvent, or the binder made from ashes mixed with lime.

It is also known from the document FR 2,516,292 to implement a method of storing radioactive waste by incorporating the waste into a coating material, incorporate the coated waste in sealed containers, and then dispose these containers in underground cavities. Such a method has the disadvantage of being much too long, expensive and complex to treat radioactive solid materials of very low activity.

He is still known by the documents DE-A-4,023,118 and DE-A-4,023,117 a process for the treatment of construction waste that is slightly contaminated by radioactivity, which consists firstly in grinding the waste likely to be into fine particles, then in a container that forms a barrier to radioactive emissions, and the waste of larger sizes which can be ground. After that, the process consists of preparing filling material consisting of cement, water and binder, to which are additionally added the previously finely ground particles of contaminated material. Finally, this filling material is introduced into containers which will be placed in underground cavities.

The processes described in the documents FR 2,516,292 and DE-A-4,023,118 have the disadvantage of not optimally taking advantage of the volume available in the underground cavities by storing containers of shapes given in these cavities, thus leading to unexploited volumes in the cavities in question.

The state of the art can also be illustrated by the teaching of the patent EP 0 724 271 B1 relating to a process for treating radioactive residues in the form of sludges by immobilizing them with a hydraulic binder to obtain a solid block which will then be stored. This method therefore consists in transforming the radioactive sludge into an immobilized compact block which can be buried after having disposed of it in a containment envelope, with the same disadvantage mentioned above concerning the lack of optimization of the available storage volumes.

The state of the art can also be illustrated by the teaching of the patent US 4,432,666 which discloses a method of depositing and discharging waste comprising parts that may be subject to emission or elution phenomena due to environmental conditions, and more particularly so-called special waste which may be a hazard to the environment. health, air or water, or be explosive or likely to burn, or contain or cause substances that could cause communicable diseases, such as toxic waste, special waste that responds to water, such as magnesium dross and acid chlorides, acidic and alkaline wastes, heavy metals, etc. One of the methods disclosed in this document is to mix the special waste in the presence of a hardener with a binder hardening by chemical reaction and which becomes water repellent after the reaction, the resulting mixture being brought to the molten or fluid state immediately in a landfill where it is about to solidify or harden. Specifically, this process aims at stacking the products of the process above the ground level, and in particular to fill, with the mixture made, the cavities of a discharge already filled with other special waste, namely the spaces separating metal or plastic drums disposed in the landfill and containing special waste. This method therefore aims to trap special waste in solid layers, directly to the air in a landfill, possibly filling the interstitial spaces between the storage drums already present in the landfill, which is completely unsuitable for the treatment of radioactive solid materials.

• on mélange une composition cimentaire sèche avec un fluide de déchets radioactifs contenant de l'eau, et on agite le mélange ;
• on introduit des particules de déchets solides fortement radioactifs dans le mélange afin de disperser uniformément ces particules ;
• on injecte le béton fluide avec la pompe d'injection dans un puit de forage, afin de remplir avec ce mélange des fissures présentes dans le puit, le béton se solidifiant ensuite à l'intérieur de ces fissures.

The state of the art can also be illustrated by teaching documents DE 20 39 130 or US 3,513,100 , which describe a process for removing highly radioactive solid waste (with a radioactivity level between 500 and 100,000 curies per gallon) by performing the following steps:

• mixing a dry cementitious composition with a radioactive waste fluid containing water, and stirring the mixture;
• highly radioactive solid waste particles are introduced into the mixture in order to uniformly disperse these particles;
• the fluid concrete is injected with the injection pump in a well, in order to fill with this mixture cracks present in the well, the concrete then solidifying inside these cracks.

Thus, the method disclosed in these documents DE 20 39 130 or US 3,513,100 aims to inject a fluid concrete containing highly radioactive solid waste in wellbore cracks. The fluid concrete used in this process is non-porous, to prevent dispersion of the radioactive particles in the aqueous phase, and contains no emulsifier and contains only a small amount of oil or other additives that could make porous concrete porous . For filling cracks that have small dimensions, this fluid concrete is probably adapted to at least partially fill the crack, provided to apply a sufficiently high injection pressure. However, this concrete without emulsifier and containing few additives would be unsuitable to completely fill a large cavity, such as a karst cavity, because of its composition which does not provide a sufficiently high fluidity.

The present invention is intended in particular to solve all or part of the disadvantages mentioned above, by proposing a radioactive solid material treatment process that is fast, economical, easy, able to optimize the available storage volume in the underground cavities , for industrial and / or bulk processing of radioactive solid materials.

• T1) concassage des matériaux solides dans une gamme de granulométrie prédéterminée ;
• T2) mélange des matériaux solides concassés avec une composition cimentaire de béton autonivelant afin de réaliser une chape fluide de béton autonivelant ;
• T3) injection de la chape fluide de béton autonivelant dans une cavité souterraine située dans un site d'enfouissement, directement au contact des parois délimitant ladite cavité.

For this purpose, it proposes a process for the treatment of radioactive solid materials comprising the following steps:

• T1) crushing solid materials in a range of predetermined particle size;
• T2) mixing the crushed solid materials with a self-leveling concrete cementitious composition in order to produce a self-leveling fluid concrete screed;
• T3) injecting the fluid self-leveling concrete screed into an underground cavity located in a landfill, directly in contact with the walls delimiting said cavity.

In the manufacture of concrete, there is a wide variety of self-leveling concrete cementitious compositions among which one skilled in the art can choose the composition that is suitable for the application and the purpose. For example, a person skilled in the art may choose, without limitation, among the self-leveling concrete cement compositions described in the following documents: FR 2 704 853 A1 , WO 00/66512 , WO 99/25664 , EP 0 934 915 A1 , WO 96/20901 , EP 1 683 768 A1 , WO 98/51637 , FR 2 919 602 A1 , FR 2 815 342 A1 and FR 2 751 956A1 .

Cementitious self-leveling concrete compositions are generally used for casting and making smooth surface screeds because they have the advantage that the surface of the cast product develops a smooth appearance and a good leveling by its own properties, such as its properties of low colloid and of great fluidity. The fluid self-leveling concrete screeds formed from such compositions thus have a particularly remarkable self-leveling and self-leveling character, including an ability to catch uneven levels without the application of external vibrations and ease of operation resulting from the ability to pump easily. and effectively fresh concrete on great heights.

The use of a cementitious composition of self-leveling concrete in the process according to the invention makes it possible to produce a fluid self-leveling concrete screed which will be easily injectable into the subterranean cavity, directly in contact with the walls delimiting this cavity, which will make it possible to fill quickly and optimally the cavity, that is to say without volume unexploited or not filled by the concrete. Indeed, because of its self-leveling qualities, the fluid screed will spread in substantially horizontal layers catching the differences in levels inherent to a natural underground cavity, knowing that such a karstic underground cavity can have dimensions (height, width) of the order of a few tens of meters to a few hundred meters.

This process thus makes it possible to treat large quantities of radioactive materials, industrially or in bulk, while ensuring efficient storage in the underground cavity.

With this treatment method according to the invention, the mineral material used by man at the beginning of the cycle to carry out his industrial activities returns to his mineral and final condition; the aggregates converted into concrete are then recycled in a sustainable manner. The principle of recycling that governs this process ensures that the aggregates that originally allowed the manufacture of concrete, return to their original form by joining the subsoil. In the end, the material will enter a slow cycle of natural reduction of its radiant activity without worry or risk for human activity.

According to a possibility of the invention, the radioactive solid materials consist of blocks and / or concrete rubble from the dismantling of buildings exposed to radioactivity.

In a particular embodiment, the concrete blocks and / or rubble are armed with a steel structure, said method comprising a preliminary deconstruction step of demolishing buildings to form concrete blocks or rubble and then separating the blocks and / or concrete rubble of the steel structure.

According to a possibility of the invention, the solid materials constitute materials whose mass radioactivity is less than 100 Becquerels per gram. Such materials, whose activity level is very close to the natural radioactivity, are particularly suitable for the process according to the invention because the injection of the fluid screed is directly in contact with the walls of an underground cavity, without coating or additional container.

In a particular embodiment, the method comprises, after the crushing step T1), a step of transporting the crushed solid materials to the burial site, by means of containers provided with radiation isolation means.

Advantageously, the injection step T3) consists in injecting the self-leveling fluid concrete screed into an underground cavity via a plurality of injection wells spaced apart from one another.

By injecting the fluid screed at several injection points of the underground cavity, the optimization of the volume available inside the underground cavity is further improved.

According to one characteristic, the method comprises a preliminary drilling step of drilling one or more injection wells at the burial site distributed along a predetermined drilling plane.

According to another characteristic, the method comprises a final step of closing the injection well (s) by filling over a predetermined height with a sealing material, in particular sand.

Advantageously, the step T3) consists in injecting the self-leveling concrete fluid screed discontinuously, in successive layers until the at least partial filling of the underground cavity.

Thus, it is possible to fill the cavity in several times with an injection of a layer which will begin to solidify or will be completely solid, before the injection of a new fluid layer.

In a particular embodiment, the method comprises, after the crushing step T1), a step of screening the crushed solid materials in several granulometric cuts, in particular cuts having a particle size of between 0 and 4 mm and / or between 4 and 10 mm. and / or between 10 and 20 mm.

This method is particularly adapted to be implemented with an underground cavity of karstic type and / or which has dimensions, in height and / or in width, of the order of a few tens of meters to a few hundred meters.

• la figure 1 est une représentation schématique des étapes de déconstruction d'un bâtiment exposé à la radioactivité, de concassage et de criblage des blocs et gravats de béton issus de la déconstruction du bâtiment dans un procédé conforme à l'invention ;
• la figure 2 est une représentation schématique des étapes de transport et de convoyage des produits concassés et criblés, issus des étapes de concassage et de criblage de la figure 1, dans un procédé conforme à l'invention ;
• la figure 3 est une représentation schématique de l'étape de mélange des produits concassés et criblés avec une composition cimentaire de béton autonivelant, pour former une chape fluide de béton autonivelant dans un procédé conforme à l'invention ;
• la figure 4 est une représentation schématique de l'étape de forage de puits d'injection dans une cavité souterraine pour un procédé conforme à l'invention ;
• la figure 5 est une représentation schématique d'un plan de forage pour un procédé conforme à l'invention ;
• la figure 6 est une représentation schématique de l'étape d'injection de la chape fluide de béton autonivelant, obtenue lors de l'étape de mélange de la figure 3, dans une cavité souterraine, via les puits d'injection forés lors de l'étape de forage illustré en figure 4, pour un procédé conforme à l'invention.

Other features and advantages of the present invention will appear on reading the detailed description below, of an example of non-limiting implementation, with reference to the appended figures in which:

• the figure 1 is a schematic representation of the steps of deconstruction of a building exposed to radioactivity, crushing and screening of concrete blocks and rubble resulting from the deconstruction of the building in a process according to the invention;
• the figure 2 is a schematic representation of the transport and conveying stages of the crushed and screened products resulting from the crushing and screening stages of the figure 1 in a process according to the invention;
• the figure 3 is a schematic representation of the step of mixing the crushed and screened products with a cementitious composition of self-leveling concrete, to form a fluid self-leveling concrete screed in a process according to the invention;
• the figure 4 is a schematic representation of the step of drilling injection wells in an underground cavity for a process according to the invention;
• the figure 5 is a schematic representation of a drilling plan for a method according to the invention;
• the figure 6 is a schematic representation of the step of injecting the fluid self-leveling concrete screed, obtained during the mixing stage of the figure 3 , in an underground cavity, via the injection wells drilled during the drilling step illustrated in FIG. figure 4 for a process according to the invention.

The invention relates to a method for treating radioactive solid materials of very low activity, that is to say having a mass radioactivity of between 1 and 100 Bq / g (100 Becquerels per gram).

This method applies more particularly to concrete blocks and / or rubble 1 armed with a steel structure 2, from the dismantling of buildings B exposed to radioactivity. Such blocks or concrete rubble generally have a particle size or blockometry of between 0 and 500 mm after demolition of the building.

This method also applies to concrete (not shown) concrete costs derived from the milling of concrete blocks or walls over a given thickness, for example of the order of 3 to 10 mm, in order to eliminate surface radioactive pollution. . Such mills generally have a particle size of between 0 and 10 mm, or even between 0 and 20 mm.

• déconstruction du bâtiment B concerné consistant à démolir le bâtiment B pour former des blocs et/ou gravats de béton 1 puis à séparer les blocs et/ou gravats de béton 1 de la structure en acier 2 ;
• concassage des blocs et/ou gravats de béton 1 dans une gamme de granulométrie, et criblage des matériaux concassés 10, 11, 12 en plusieurs coupures granulométriques ;
• transport des matériaux concassés 10, 11, 12 à l'intérieur de conteneurs 3 sur un site d'enfouissement dans lequel est située une cavité souterraine C, notamment du type cavité karstique ;
• mélange des matériaux concassés 10, 11, 12 avec une composition cimentaire de béton autonivelant 4 afin de réaliser une chape fluide de béton autonivelant 5 ;
• forage de plusieurs puits d'injection 6 sur le site d'enfouissement répartis selon un plan de forage prédéterminé au-dessus de la cavité souterraine C ;
• injection de la chape fluide de béton autonivelant 5 dans la cavité souterraine C via les puits d'injection 6, directement au contact des parois délimitant ladite cavité C ;
• fermeture des puits d'injection 6 par remplissage sur une hauteur prédéterminée avec un matériau de bouchage, notamment du sable prêt à l'emploi ou du béton hydraulique classique.

This process comprises the following steps:

• deconstruction of the concerned building B consisting of demolishing the building B to form concrete blocks and / or rubble 1 and then separating the concrete blocks and / or rubble 1 from the steel structure 2;
• crushing the blocks and / or concrete rubble 1 in a range of particle size, and screening the crushed materials 10, 11, 12 in several granulometric cuts;
• transporting crushed materials 10, 11, 12 inside containers 3 to a landfill site in which an underground cavity C is located, in particular of the karst cavity type;
• mixing the crushed materials 10, 11, 12 with a cementitious self-leveling concrete composition 4 in order to produce a fluid self-leveling concrete screed 5;
• drilling of several injection wells 6 at the landfill distributed along a predetermined drilling plane above the underground cavity C;
• injecting the fluid self-leveling concrete screed 5 into the underground cavity C via the injection wells 6, directly in contact with the walls delimiting said cavity C;
• closing the injection wells 6 by filling a predetermined height with a sealing material, in particular ready-to-use sand or conventional hydraulic concrete.

Regarding the deconstruction stage schematized partly on the figure 1 , the latter is carried out by means of deconstruction equipment provided with specific protection means against radiation.

• un ensemble bras/balanciers longs, notamment d'une longueur de 25 m ;
• un porte-outil hydraulique pouvant recevoir une attache rapide hydraulique ;
• un brise roche hydraulique, monté sur le porte-outil, par exemple d'une gamme de 3,5 tonnes ; et
• une cabine orientable dotée d'un système de traitement de l'air avec des moyens de pressurisation de la cabine et des moyens de filtration, et d'un système de contrôle dosimétrique du niveau de radioactivité.

To carry out the demolition of the building, it is conceivable to use a hydraulic excavator or excavator, for example a range of 80 tons, configured in demolition mode and provided with:

• a long arms / pendulums assembly, in particular of a length of 25 m;
• a hydraulic tool holder for receiving a hydraulic quick coupler;
• a hydraulic rock breaker, mounted on the tool holder, for example a range of 3.5 tons; and
• a steerable cabin equipped with an air treatment system with means for pressurizing the cabin and filtration means, and a dosimetric control system of the level of radioactivity.

This hydraulic excavator is for example able to ensure the demolition of walls, wall or floor type, and the beams of building B, reinforced concrete in a block size between 0 and 500 mm.

To continue the demolition of the concrete blocks and / or rubble 1 armed with the steel structure 2, the tool holder of the shovel can also carry, via a hydraulic quick coupler, a hydraulic shear to cut the steel elements (scrap type or metal reinforcement) and concrete elements (beam or wall type) and achieve the optimum blockometry for the next crushing step, namely between 0 and 500 mm.

To enable sorting and handling of materials, the excavator's tool holder can also carry a bucket and a hydraulic grapple via a hydraulic quick coupler.

The various hydraulic attachments of the various tools, such as the hydraulic rock breaker, the hydraulic shear, the bucket or the hydraulic grapple, have the advantage, in addition to saving time of replacement, to avoid any unprotected human intervention. radiation; the driver of the shovel can, from his cabin under confinement, change tool at will without being exposed.

To convey the concrete and steel elements from the aforementioned demolition step, a mobile wheel loader takes the materials concrete / steel blockometry between 0 and 500 mm to feed the crushing means described below. This loader, like the shovel or the excavator, has a system of treatment and filtration of the air, as well as a system of dosimetric control of the level of radioactivity.

The dosimetric control systems installed respectively on the excavator or the excavator and on the loader can be connected to a central safety cell located on the deconstruction site, in order to teletransmit and record the radioactivity data to maintain a traceability of the risk. .

In general, the collection of radioactivity data and other safety information is generalized in all other stages of the treatment process, both at the deconstruction site and at the landfill site.

Regarding the crushing step schematized partly on the figure 1 , the latter is done in two stages with a first crushing, said primary crushing, and a second crushing, said secondary crushing.

• une trémie de réception, par exemple d'un volume de l'ordre de 15 m³, alimenté par la chargeuse en matériaux béton/acier de blocométrie comprise entre 0 et 500 mm ;
• un alimentateur vibrant ;
• un concasseur à mâchoires pourvu notamment de moyens de débourrage et d'un système de réglage hydraulique de la pression des mâchoires, ledit concasseur à mâchoires étant apte à produire des matériaux en béton de blocométrie comprise entre 0 et 200 mm ;
• un système de déferraillage conçu pour séparer les morceaux de béton issus du concasseur à mâchoires des éléments en acier, ledit système de déferraillage comprenant un électro aimant conçu pour le prélèvement des éléments en acier combiné à un overband magnétique de déferraillage ;
• un convoyeur de sortie ; et
• un convoyeur de stockage des matériaux de blocométrie comprise entre 0 et 200 mm.

The primary crushing step can be provided by a first crushing device, in particular of the mobile type mounted on a crawler, with a power supply. This first crushing device can comprise:

• a receiving hopper, for example of a volume of the order of 15 m ³ , fed by the loader material concrete / steel blockometry between 0 and 500 mm;
• a vibrating feeder;
• a jaw crusher provided in particular with unclogging means and a hydraulic adjustment system of the pressure of the jaws, said jaw crusher being able to produce blocking concrete materials between 0 and 200 mm;
• a defrosting system for separating the concrete pieces from the jaw crusher from the steel members, said defrosting system comprising an electromagnet designed to pick up the steel elements combined with a magnetic de-grinding overband;
• an exit conveyor; and
• a storage conveyor of blockometry materials between 0 and 200 mm.

The first crushing device is advantageously remotely controlled by the driver of the loader described above; the latter can for example, from his cabin, modulate the feed rate of the first crushing device.

• un système de dessablage par criblage ;
• un concasseur giratoire assurant un broyage dans une coupure granulométrique entre 0 et 20 mm, pourvu de moyens de recyclage des gravats de 20 mm.

The secondary crushing step consists in producing concrete materials with a grain size between 0 and 20 mm, using blockometry concrete materials between 0 and 200 mm. This secondary crushing step can be provided by a second crushing device which comprises:

• a sanding system by screening;
• a gyratory crusher providing grinding in a grain size cut between 0 and 20 mm, provided with means of recycling rubble 20 mm.

The screening step of the crushed materials, coming from the second crushing device, in several granulometric cuts is carried out by means of a screening device fed with crushed materials having a particle size of between 0 and 20 mm.

• une première coupure 10, dite sable 0/4, de granulométrie comprise entre 0 et4mm;
• une deuxième coupure 11, dite agrégats 4/10 de granulométrie comprise entre 4 et 10 mm ; et
• une troisième coupure 12, dite agrégats 10/20, de granulométrie comprise entre 10 et 20 mm.

This screening device provides a screening in several granulometric cuts, in particular the following grain size cuts:

• a first cut 10, called sand 0/4, of particle size between 0 and 4 mm;
• a second cut 11, said 4/10 aggregates of particle size between 4 and 10 mm; and
• a third cut 12, said aggregates 10/20, with a particle size of between 10 and 20 mm.

The cuts having a particle size greater than 20 mm are recycled in the second crushing device in order to undergo the secondary crushing step again.

The aggregates 10, 11, 12 or materials resulting from the screening step are then stored in respective silos, for example metal silos, before being loaded into the respective transport containers 3 used in the next step of transport. Each container 3 corresponds to aggregates in a given cut, for example in the first or second or third cut.

The step of transporting the aggregates 10, 11, 12, resulting from the various steps mentioned above carried out on the deconstruction site, to the landfill site is carried out by means of the specific containers 3 visible on the figures 1 and 2 .

These containers 3 are of course compliant in their geometry and dimensions to the standards of international transport, being in particular compatible with means of road and rail transport. Only the upper part 30 and the rear door 31 are specific to the intended use, namely the transport of very low-level radioactive materials.

The discharge of aggregates 10, 11, 12 to the landfill is effected for example mainly by rail. On the landfill, the containers 3 can arrive by train if a rail junction is possible, otherwise they will be transhipped on trailer seedlings 7 equipped with container carrier 70 for the final journey, as illustrated in FIG. figure 2 .

To achieve this stage of rail and road transport, the containers 3 are provided with sealing means and are fully enclosed to achieve the desired seal. It is also envisaged to carry out this transport with sealed trailer seedlings.

The containers 3 are sized to contain for example about 20 tons of aggregates; this payload capacity being compatible with the legislation for loading on trailer seedlings 7 equipped with container ships 70.

The containers 3 have in the upper part 30 hatches 32 allowing loading under hopper by means of a flexible handle, for example with a diameter of 300 mm.

These traps 32, for example three in number, are circular in shape and allow sufficient gravity filling containers. The upper portion 30 has a double slope roof shape to optimize the gravity loading per sleeve to complete the 20 tons planned. The rear door 31 and the hatches 32 are provided with sealing means and appropriate closure to prevent any loss of materials during transport.

As visible on the figure 2 , the container holder 70 has a rear hinge 71 and a front ram 72 for unloading materials 10, 11, 12 transported in a receiving hopper 73 on the landfill site.

The receiving hopper 73 opens onto a conveyor line 74, for example of the conveyor belt line type, which leads the materials into corresponding storage silos. The materials are thus stored in three granulometric cuts 10, 11, 12 in three silo batteries.

Under these storage silos are arranged three respective extractors provided with weight control means, or weight control means, which will be used for a pre-dosing of the materials according to their grain size cuts; this pre-dosing being necessary for the next mixing step.

Regarding the mixing step consisting in producing a self-leveling fluid concrete screed 5 and partly diagrammed on the figure 3 , the latter is carried out essentially in a concrete plant 8, provided with a mixer 80.

The concrete plant 8 is supplied with materials 10, 11, 12 crushed and screened via the respective extractors.

The concrete plant 8 is supplied with cementitious self-leveling concrete composition 4 via one or more conveying lines fed with cement and admixtures, not counting water. The concrete plant 8 is thus equipped with two or more cement silos, as well as additional tanks and / or silos for the storage of the adjuvants.

The mixing step is for example controlled by computer control means controlling the feeds of aggregates, cement, admixtures and water, as well as speed and mixing times.

The entire concrete plant 8 is confined in a building that is impervious to water and air, in particular by means of a filtering depressurization device.

Regarding the drilling step schematized partly on the Figures 4 and 5 , the latter is carried out essentially using a drill, including the type "bottom hole" hammer whose standard diameter is for example six inches and equipped with eight-inch cutters.

The depth of the injection wells 6 (or boreholes) is adapted to the depth of the cavities C in a range of 40 to 500 m.

The injection wells 6 will, if necessary, be jacketed with tubes sealing the well, such as for example thermoplastic polymer tubes, such as polyvinyl chloride or high density polyethylene, or steel tubes.

As visible in figure 5 the injection wells 6 are spaced from each other and distributed along a predetermined drilling plane, such as a mesh of predefined width L, in particular of the order of 40 m. This means that the drilling will take place on an area where the injection and 6 injection are spaced from each other at least a distance L of 40 meters.

Regarding the injection step schematized partly on the figure 6 , the latter is carried out essentially by means of pipes 90 and one or more concrete pumps for circulating the fluid screed 5 in the pipes 90.

In order to avoid the manipulation of the fluid screed 5 out of confinement, this fluid screed 5 will thus be conveyed from the concrete batching plant 8 to the injection well 6 via the pipes 90 and by a pump, in particular of the concrete pump type. . Relay pumps may be required depending on the length of the pipes 90 and the extent of the landfill.

The heads 60 of the injection wells 6 are closed and covered by valve and shutter devices mounted on the pipes 90. The fluid screed 5 is injected at low pressure into the injection wells 6.

As schematized in figure 6 due to its self-leveling and colloidal qualities, the fluid screed 5 is layered up to about 20 m from the axes of the injection wells 6.

The cavity C is thus filled progressively in successive layers until the total filling of the cavity C.

The injection of the fluid screed 5 can be made either continuously or discontinuously.

With discontinuous pouring, it is possible to spread over time the filling of the cavity C, the objective being the storage of materials that will solidify quickly.

The self-leveling concrete thus cast and solidified has very low propensities for weathering over time.

The last step of closing the injection wells 6 is performed when the cavity C is full, the injection wells 6 being plugged or condemned by filling with sand over a height H, for example at least 30 meters. The heads 60 of the injection wells 6 are then sealed after having been fitted with sheaths that may, for example, house sensors for controlling the radiating activity in order to follow the decay in the time of the radioactivity.

Claims (12)

Process for the treatment of radioactive solid materials (1) comprising the following steps: T1) crushing solid materials (1) in a range of predetermined particle size; T2) mixing the crushed solid materials (10, 11, 12) with a cementitious self-leveling concrete composition (4) to provide a self-leveling fluid concrete screed (5); T3) injecting the self-leveling fluid concrete screed (5) into an underground cavity (C) located in a landfill, directly in contact with the walls delimiting said cavity (C). The method of claim 1, wherein the radioactive solid materials (1) consist of concrete blocks and / or rubble from the dismantling of buildings (B) exposed to radioactivity. A method according to claim 2, wherein the concrete blocks and / or rubble (1) are reinforced with a steel structure (2), said method comprising a preliminary deconstruction step of demolishing buildings (B) to form blocks or concrete rubble (1) and then separating the concrete blocks and / or rubble (1) from the steel structure (2). Process according to any one of claims 1 to 3, in which the solid materials (1) constitute materials whose mass radioactivity is less than 100 Becquerels per gram. Process according to any one of claims 1 to 4, comprising, after the crushing step T1), a step of transporting the crushed solid materials (10, 11, 12) to the landfill, by means of containers ( 3) provided with sealing means. Process according to any one of claims 1 to 5, wherein the injection step T3) consists in injecting the self-leveling concrete fluid screed (5) into the underground cavity (C) via a plurality of injection wells (6). spaced apart from each other. A method as claimed in any one of claims 1 to 6, comprising a pre-drilling step of drilling one or more injection wells (6) at the burial site distributed along a predetermined drilling plane. Process according to claims 6 or 7, comprising a final step of closing the injection well (s) (6) by filling a predetermined height with a sealing material, in particular sand. Method according to any one of the preceding claims, in which the step T3) consists of injecting the self-leveling concrete fluid screed (5) discontinuously, in successive layers until the at least partial filling of the underground cavity (C) . Process according to any one of the preceding claims, comprising, after the crushing step T1), a step of screening the crushed solid materials (10, 11, 12) in several granulometric cuts, in particular cuts of particle size between 0 and 4 mm and / or between 4 and 10 mm and / or between 10 and 20 mm. A method as claimed in any one of the preceding claims, wherein the underground cavity (C) is a karstic cavity. Method according to any one of the preceding claims, wherein the underground cavity (C) has dimensions, in height and / or width, of the order of a few tens of meters to a few hundred meters.

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