Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
  • G21F9/28—Treating solids
  • G21F9/30—Processing
  • G21F9/301—Processing by fixation in stable solid media
  • G21F9/307—Processing by fixation in stable solid media in polymeric matrix, e.g. resins, tars
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
  • G21F9/28—Treating solids
  • G21F9/30—Processing
  • G21F9/301—Processing by fixation in stable solid media
  • G21F9/302—Processing by fixation in stable solid media in an inorganic matrix
  • G21F9/304—Cement or cement-like matrix
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
  • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
  • G21F9/28—Treating solids
  • G21F9/34—Disposal of solid waste

Definitions

• the subject of the invention is a block for packaging powdered waste for storage and a method for manufacturing such a block.
• thermosetting polymer and hardened cement More specifically, it relates to the packaging of waste in a composite matrix of thermosetting polymer and hardened cement. It applies to the packaging of waste of different types, such as radioactive waste from the nuclear industry, waste from the chemical industry and more generally all the waste which must be stored in a leach-resistant matrix.
• thermosetting polymers there are currently several methods for conditioning radioactive waste using matrices such as cements, bitumens, thermosetting polymers and more recently composite matrices comprising both thermosetting polymers and cements.
• document EP-A-0 274 927 describes the packaging of waste in a composite matrix consisting of epoxy resin and hardened cement. To carry out this conditioning, the waste and the cement are first mixed dry, then, at ambient temperature, this mixture is added to an emulsion formed by the epoxy resin, the cement mixing water and the hardener. A packaging block is thus obtained containing 35 to 45% by weight of waste, 20 to 40% by weight of epoxy resin and 25 to 35% by weight of cement with its water of hydration.
• the present invention specifically relates to a packaging unit for powdered waste, which can contain a higher proportion of waste, while ensuring efficient and safer containment of this waste.
• the packaging block for waste powder in a composite matrix of thermosetting polymer and hardened cement is characterized in that the waste powder is coated in the thermosetting polymer and in that the coated powder is dispersed in cement.
• the mineral part constituted by the cement and its water of hydration constitutes the rigid skeleton of the block whereas the thermosetting polymer which creates a gangue around the waste powder, has an elastic behavior.
• the quantity of conditioned waste can be greater and reach 55% by weight.
• Powdered waste can consist in particular of incineration ash from combustible radioactive waste such as low and medium activity waste contaminated with ⁇ emitters or ⁇ - ⁇ emitters.
• These ashes consist essentially of a mixture of metal oxides such as silica, iron oxide, alumina, etc.
• thermosetting polymers of the composite matrix can be of different types.
• epoxy resins are used.
• the cements used in the block can be of various types.
• a cement with low heat of hydration such as CLK, CLC cements, etc. is used.
• step b the late introduction (step b) of the water necessary for the hydration of the cement makes it possible to coat the waste powder well in the thermosetting polymer and to avoid bringing it into contact with water .
• the presence of water is not favorable for a good coating of the powder in the polymer, because the water forms a thin layer on the whole of the waste, which is harmful to obtain the adhesion of the polymer on the powder.
• the waste may have a hydrophilic affinity detrimental to good hydration of the cement.
• step a) of the process of the invention a partial hardening of the polymer is carried out. This is preferably done at a temperature above room temperature, but below 100 ° C. This temperature is chosen as a function of the polymer used, the reaction kinetics of the polymer, the rheological properties of the overall system and the surface tensions.
• step b) the introduction of water into the mixture makes it possible to cool the medium before adding the cement to constitute the final block.
• the mixture of water and polymer-coated powder is further cooled so as not to exceed a temperature of 40 ° C.
• the amount of water added is chosen in an appropriate manner to control the hydration of the cement and limit the water / cement ratio, thereby promoting the quality of the concrete thus obtained. In fact, when this ratio increases, it promotes the hydration of the cement which is better, but disadvantages the quality of the structure of the concrete thus obtained by creating larger pores.
• the amounts of water and cement added are such that the water / cement ratio is from 0.4 to 0.6.
• a ratio of about 0.5 is used, which corresponds to a maximum cement hydration energy.
• the hydration of the cement leads to an increase in the temperature of the mixture, which causes post-curing of the thermosetting polymer and improves its physico-chemical properties by increasing its cross-linking rate.
• the temperatures used in the various stages therefore play a very important role.
• step a) the increase in temperature due to the partial hardening of the polymer results in an increase in the wetting power of the polymer for the powdered waste, while the absence of water improves the adhesion of the polymer. on powdered waste.
• Plastic behavior of the polymer is preferred to viscous behavior for coating the grains of waste powder in the form of beads.
• the mixing phase optimizes, as a first step, the wetting of the waste powder by the polymer and the hardener in the absence of water, and makes it possible to control the release of crosslinking energy in order to obtain a three-dimensional network. polymerized which forms an envelope on the waste powder grains.
• Steps a), b), and c) can take place in a mixing reactor, so that the amount of energy released by the polymerization does not occur in the final storage drum.
• step a) by performing step a) at a temperature above ambient, the resulting enthalpy of polymerization in the waste package is lower.
• the packaging blocks obtained in accordance with the invention therefore have numerous advantages.
• thermosetting polymer They have a better resistance to leaching due to the encapsulation of the waste powder grains in the thermosetting polymer and the possibility of using the quantity of water just necessary to hydrate the cement, which avoids including in the block of water not bound to the cement, which may be rejected later during storage of the block.
• the crosslinking rate of the polymer is high, which makes it more waterproof; this is due in particular to the fact of hardening the cement after hardening of the polymer.
• an epoxy resin and a thermosetting polymer are used.
• a hardener consisting of a diamine (diamino-diphenylmethane)
• the cement used is an D'ORIGNY CLC 45 cement of the marine type.
• incineration ash having the following composition is conditioned: CaO: 28% by weight If: 30% by weight CuO: 7.8% by weight Al2O3: 9.4% by weight TiO: 3.1% by weight MgO: 2.8% by weight Fe2O3: 0.7% by weight CO2: 17.4% by weight Cl: 2.3% by weight SO3: 1.3% by weight
• 49 parts by weight of ash having the composition given above are mixed and kneaded, for at least 30 minutes, with 16 parts by weight of epoxy resin, then 9 parts by weight of hardener are added. The whole is mixed at 60 ° C for 40 minutes. 9 parts by weight of water are then added and the mixture is cooled to ambient temperature of 25 ° C. while stirring. At this time, 17 parts by weight of cement are added to the mixture, then the whole is homogenized and it is poured into a storage drum.
• the rate of progress of the polymerization is of the order of 92%.
• the hydration of the cement increases the temperature of the mixture in the barrel, which leads to annealing of the polymer and increases the crosslinking rate by around 2.5%.
• the compressive strength of the blocks obtained is 50 to 60 MPa.
• incineration ashes having the same composition as those of Example 1 are coated using the same epoxy resin and the same cement.
• 18 parts by weight of epoxy resin are introduced into 45 parts by weight of ash, the whole is mixed and kneaded for at least 30 minutes, then 9 parts by weight of hardener are added. The whole is mixed at 50 ° C for 45 minutes. 8 parts by weight of water are then added and the mixture is cooled to ambient temperature of 25 ° C. At this time, 20 parts by weight of cement are introduced into the mixture, then the mixture is homogenized and poured into a storage drum. At the time of casting, the degree of progress of the polymerization is of the order of 80%.
• the increase in temperature due to the hydration of the cement causes the annealing of the polymer and increases the crosslinking rate of the order of 8%.
• the compressive strength of the block obtained is 45 to 55 MPa
• incineration ash having the following composition is coated: CaO: 41.1 by weight If: 4.3 by weight CuO: 0.1 by weight Al2O3: 28.3 by weight TiO: 6.7 by weight MgO: 4.0 by weight Fe2O3: 1.4 by weight CO2: 10.6 by weight Cl: 2.3 by weight SO3: 1.2 by weight
• the degree of progress of the polymerization is of the order of 91%.
• the increase in temperature due to the hydration of the cement causes the polymer to anneal and increases the crosslinking rate by around 3%.
• the compressive strength of the block obtained is 50 to 65 MPa.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Environmental & Geological Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Processing Of Solid Wastes (AREA)

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Cited By (1)

Citations (4)

• 1994
  • 1994-09-21 FR FR9411249A patent/FR2724757B1/fr not_active Expired - Fee Related
• 1995
  • 1995-09-19 EP EP19950402107 patent/EP0703586B1/de not_active Expired - Lifetime
  • 1995-09-19 ES ES95402107T patent/ES2129178T3/es not_active Expired - Lifetime
  • 1995-09-19 DE DE1995607230 patent/DE69507230T2/de not_active Expired - Fee Related

Patent Citations (4)

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