EP1776707B1 - Method and device for removing flammable gases from a sealed chamber and chamber equipped with one such device - Google Patents
Method and device for removing flammable gases from a sealed chamber and chamber equipped with one such device Download PDFInfo
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- EP1776707B1 EP1776707B1 EP05797769A EP05797769A EP1776707B1 EP 1776707 B1 EP1776707 B1 EP 1776707B1 EP 05797769 A EP05797769 A EP 05797769A EP 05797769 A EP05797769 A EP 05797769A EP 1776707 B1 EP1776707 B1 EP 1776707B1
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- catalyst
- chamber
- microporous
- possibly
- support
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- 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
- G21F5/00—Transportable or portable shielded containers
- G21F5/06—Details of, or accessories to, the containers
Definitions
- the invention relates to a method and a device for eliminating flammable gases, such as hydrogen, in a closed chamber containing radioactive materials, in the presence of solid or liquid organic compounds and possibly water capable of producing such substances. gas, by radiolysis, or when the radioactive materials include such compounds and possibly water.
- gases such as hydrogen
- the invention also relates to a closed enclosure such as a container, tank, or container intended for the transport or storage of radioactive materials in the presence of organic compounds and possibly water, or comprising components of this type, said enclosure being equipped with such a flammable gas elimination device.
- the invention can be used in any closed chamber in which are enclosed radioactive materials containing organic compounds and optionally water, or radioactive materials in the presence of organic compounds and optionally water.
- radioactive materials may be technological waste coming from a manufacture or treatment of fuel elements for a nuclear reactor or from such a reactor.
- Nuclear installations such as fuel element fabrication workshops for nuclear reactors generate a certain amount of waste, known as "technological waste”.
- This technological waste can include objects and materials of very different natures such as engine parts, filters, scrap metal, rubble, glasses, etc. It also contains organic materials based on cellulose. such as paper, wood, cotton, or in the form of plastics such as vinyl or polyurethane packaging covers, boots, gloves, and miscellaneous objects of polymeric materials. All this waste can also contain small amounts of liquids such as water and organic liquids (oils, hydrocarbons, etc ). All these wastes in themselves constitute radioactive materials, because they are metal parts activated during their stay in the facilities, or organic or other materials contaminated with uranium or radioactive plutonium powder when they are used in these facilities. same facilities.
- transport is generally carried out by packaging the technological waste in containers such as drums, trash cans or cases and then placing these containers in containers.
- flammable gases particularly hydrogen by radiolysis
- the radiolysis gases are then released in a confined volume, so that a high concentration of flammable gases can be reached rapidly if the nature of the waste and the intensity of the radiation lead to a large production of these gases.
- This problem is particularly critical during transport, because then a large number of waste containers are usually placed in the same container, in order to optimize the transport capacity. Indeed, this has the effect of reducing the free space available in the container for flammable gases that escape waste and containers.
- the waste containers often themselves have a certain tightness, because they are closed by crimped lids that can be provided with gaskets.
- the flammable gases preferentially accumulate in the residual free space existing inside each of the containers. Because these volumes are also very small, this can lead to significant concentrations of flammable gases in the packaging containers themselves.
- flammable gases produced by radiolysis are an explosive mixture when they are in contact with other gases such as air, when their concentration exceeds a certain value. limit, known as the "flammability threshold".
- the flammability threshold is variable depending on the nature of the flammable gas and the temperature and pressure conditions. In the case of hydrogen, the flammability threshold in air is around 4%. This means that when the concentration of hydrogen in the air exceeds this threshold, a source of heat or a spark may be sufficient to ignite the mixture or to produce a violent explosion in a confined space.
- a technique for removing flammable gases such as hydrogen located inside a closed enclosure such as a radioactive waste transport container is based essentially on the introduction into the chamber of a recombination catalyst oxygen and hydrogen in water (or catalytic recombinant hydrogen), in contact with which hydrogen combines with the oxygen present in the air cavity to form water according to the mechanism of catalytic oxidation of hydrogen.
- the document EP-A-0 383 153 discloses a device for reducing the internal pressure in a radioactive waste storage container.
- This device comprises an enclosure placed in an opening of the wall or the lid of the nuclear waste storage container.
- the interior of this chamber receives a catalyst and has an opening in communication with the interior of the storage container in which is placed a sintered metal candle.
- the catalyst is separated from the outside by a wire cloth, a vapor permeable plate or a sintered metal cover.
- the hydrogen that has formed in the storage vessel passes through the sintered metal candle and arrives on the catalyst where the hydrogen is oxidized into water by the oxygen in the air.
- the catalyst used comprises a precious metal, for example palladium on an inert support, for example alumina.
- an external source of oxygen constituted by the ambient air is used, which can not be envisaged for closed, hermetic enclosures or perfectly sealed packages.
- EP-A-0 660 335 discloses a device for reducing overpressures in waste storage tanks, in particular radioactive waste generating hydrogen, wherein a hydrogen recombination catalyst with oxygen and a desiccant are placed in a closed envelope located inside the storage tank and in communication with its environment via a bursting disc.
- above the separation sheet are two grids supporting the recombination catalyst.
- separator sheet above the separator sheet is a layer of an oxidizing agent which is held in place by a gas permeable separator sheet.
- the desiccant is chosen for example from silica gel, molecular sieves, dehydrated complexing agents such as, for example, copper sulphate or hygroscopic chemicals such as calcium chloride, magnesium sulphate, or pentoxide. phosphorus, optionally on a support material.
- the recombination catalyst is chosen in particular from platinum or palladium-coated catalysts. In this device, the recombiner becomes inoperative once all the oxygen in the chamber has been consumed.
- the document FR-A-2 061 573 discloses a gas purification process which uses the successive passage of the gas on two catalysts with oxygen supply from the outside.
- the object of the invention is to provide a method and a device that meet, among others, all the needs listed above.
- the object of the invention is further to provide a method and a device which do not have the disadvantages, limitations, defects and disadvantages of the methods and devices of the prior art and which provide a solution to the problems posed by the methods and devices of the prior art.
- prior art such as those described in the documents EP-A-0 383 153 and EP-A-0 660 335 .
- the oxidation reaction of the flammable gases by the oxygen contained in the chamber atmosphere is generally, essentially, a reaction of oxidation of hydrogen into water.
- the catalyst a) is a catalyst for at least the oxidation reaction of hydrogen in water.
- the catalyst a) supported by an inert solid support constitutes a first active product which allows the continuous removal of flammable gases, and in particular hydrogen, produced by radiolysis of the molecules, organic compounds and optionally water at room temperature. inside the enclosure.
- Catalyst a) of this oxidation reaction which is supported by an inert solid support, may be a precious metal which is advantageously selected from the group consisting of platinum, palladium, and rhodium.
- the precious metal is present in an amount which is generally less than 0.1% by weight.
- Either the catalyst a) of this oxidation reaction may be a rare earth, advantageously chosen from the group of lanthanides such as lanthanum.
- the catalyst support a) is an inert solid support.
- inert support is meant a support which does not react chemically with the compounds in the enclosure, the atmosphere thereof, and the other active products.
- the catalyst support a) is a microporous solid inert carrier.
- This microporous support is generally chosen from the optionally activated molecular sieves.
- activated is a term commonly used in this field of the art, which means that the compound forming the molecular sieve such as alumina has undergone a particular thermal treatment in particular, to increase its specific surface area.
- This molecular sieve is preferably a material selected from aluminas and activated aluminas.
- the solid, inert, microporous support generally has a high specific surface area, ie a surface area generally of at least 200 m 2 / g, preferably at least 300 m 2 / g.
- the catalyst b) comprises a second active product, it catalyses the oxidation reaction of CO to CO 2.
- catalyst b) is a specific catalyst for the CO 2 oxidation reaction in CO 2 .
- catalyst b) comprises a mixture of manganese dioxide MnO 2 and copper oxide CuO.
- the method according to the invention uses a combination of two active products, specific catalysts a) and b) which has never been described in the prior art as represented in particular by the documents EP-A-0 383 153 and EP-A-0 660 335 .
- the process according to the invention essentially because of the use of such a specific combination of active products, catalysts a) and b), meets the needs and requirements listed above and provides a solution to the problems posed by the processes. of the prior art.
- the inventors have been able to demonstrate that the efficiency processes of the prior art are greatly reduced in the presence of other radiolysis gases such as carbon monoxide CO; this decrease in efficiency is explained by a poisoning of the oxidation catalyst of H 2 (a)) such as palladium, by CO carbon monoxide.
- Catalyst b) ensures the continuous removal of carbon monoxide, by oxidation, to give carbon dioxide which causes no problem of poisoning catalyst a).
- the method according to the invention makes it possible to effectively remove, over a very long time, or even a virtually unlimited duration, flammable gases such as hydrogen, contained in the closed chamber. It retains a high degree of efficiency irrespective of the waste contained in the enclosure and in particular when the waste contains organic carbon and hydrogen compounds capable of releasing both CO and hydrogen.
- the process according to the invention functions perfectly in the presence of various radiolysis gases which are in addition to hydrogen, for example CO, CO 2 , etc.
- the process according to the invention likewise functions perfectly in a wide range of temperatures and in particular at negative temperatures and under irradiation whatever the nature of the latter.
- a source of oxygen c there is placed inside the enclosure, in addition to the two catalysts a) and b) which are always present, a source of oxygen c).
- This source of oxygen is a third optional active product that makes it possible to overcome the lack of oxygen, once all the oxygen initially present in the chamber has been consumed.
- This source of oxygen can be either in gaseous form or in solid form.
- the oxygen source is in solid form, it is generally chosen from solid peroxides. These compounds release oxygen in the presence of water which is for example the water formed during the oxidation of hydrogen by the catalyst a).
- These solid peroxides are generally selected from alkali and alkaline earth metal peroxides and mixtures thereof such as calcium peroxide, barium peroxide, sodium peroxide, potassium peroxide, magnesium peroxide and mixtures thereof.
- the oxygen source is in gaseous form, it is generally formed in replacing all or part of the atmosphere of the enclosure with pure oxygen.
- a microporous hygroscopic inert solid support d is also placed inside the enclosure.
- the hygroscopic microporous inert solid support constitutes a fourth optional active product, making it possible to continuously ensure the lowering of the hygrometric degree of the atmosphere of the enclosure, by adsorption of water.
- the amount of water removed generally represents from 15% to 30% of the weight of the microporous hygroscopic support.
- the residual moisture inside the chamber is thus kept at a low value, for example less than 10% (humidity level) until saturation of said support.
- the hygroscopic microporous support is preferably chosen from molecular sieves.
- the molecular sieve of the microporous inert solid support d) is made of a material chosen from silico-aluminate type materials, for example of formula Na 12 [(AlO 2 ) 12 (SiO 2 ) 12] XH 2 O, with X up to 27, or 28.5% by weight of the anhydrous product.
- the hygroscopic microporous support generally has a high specific surface area, i.e. at least 200 m 2 / g, preferably at least 300 m 2 / g.
- this fourth active product is particularly present in the case where the third active product is constituted by a source of gaseous oxygen. Indeed, in this case, the presence of water that would not have been absorbed by the catalyst support a) such as alumina, is not necessary to generate oxygen, contrary to the case where the Oxygen source consists of a solid peroxide that releases oxygen only in the presence of water.
- the solid inert microporous support supporting the catalyst a); catalyst b); and optionally the oxygen source c) and the microporous hygroscopic support d) are in the form of discrete elements, particles, such as for example crystals, beads or granules optionally forming a powder.
- the solid inert carrier preferably microporous, supporting the catalyst a); catalyst b); and the hygroscopic microporous support d), if any, are fractionated into discrete elements, such as for example crystals, beads or granules, having an envelope diameter generally of between about 2 mm and about 20 mm.
- envelope diameter designates the diameter of a fictional sphere constituting the envelope of said element.
- the active product c) is advantageously in a finely divided form such as a powder.
- the active products a), b) and optionally c) and d) are placed, mixed or separately, in at least one container, at least partially permeable, such as a textile envelope, a strainer, a wire mesh , or a container pierced with holes, such as a cartridge.
- a container at least partially permeable, such as a textile envelope, a strainer, a wire mesh , or a container pierced with holes, such as a cartridge.
- the active products a) and b) are mixed.
- each of the active products can be dispersed between two screens in the form of superposed layers or form a single layer with a mixture of the two mandatory active products a) and b), each of the optional active products c) and d) being separately packaged. for example in the form of separate layers.
- the mass ratio between the catalyst b) and the catalyst a) is generally from 1/1 to 1/10, preferably from 1/2 to 1/4, this mass ratio being generally given for a ratio of the flow rate of CO on the flow rate of H 2 generally about 1:11.
- the invention also relates to a closed enclosure, which is a container, tank or container, intended for the transport and / or storage of radioactive materials, said closed enclosure being capable of containing radioactive materials comprising organic compounds and optionally water, or radioactive materials in the presence of organic compounds and possibly water, capable of producing flammable gases, by radiolysis, said enclosure further containing at least one flammable gas elimination device as defined above.
- the invention applies to any closed enclosure, in which are placed radioactive materials which comprise organic compounds and possibly water, or radioactive materials which are in the presence of organic compounds and optionally water.
- organic compound means a compound comprising at least one carbon atom, at least one hydrogen atom and optionally at least one other atom chosen, for example, from nitrogen, sulfur or phosphorus atoms. oxygen, and halogens.
- This enclosure may have any shape and dimensions, and a level of sealing greater or less, without departing from the scope of the invention. It may especially be a container such as a drum or a container of cylindrical or parallelepiped shape. Moreover, the enclosure can be indifferently for the transport, storage or treatment of the radioactive material concerned.
- the radioactive materials placed in the closed chamber may be constituted by all the radioactive materials comprising organic compounds and possibly water, or by all the radioactive materials in the presence of organic compounds and possibly water.
- the invention applies more particularly to the case where said compounds Organic compounds are compounds that in addition to hydrogen emit, produce CO and CO 2 such as certain plastics. Indeed, it has been demonstrated according to the invention that the CO poisons the catalyst a) and can be effectively removed by the catalyst b) to preserve the effectiveness of the catalyst a).
- the radioactive materials may be constituted by technological waste from a plant for the treatment or manufacture of nuclear fuel elements.
- wastes are contaminated with plutonium or radioactive uranium and may contain a certain fraction of water or solid or liquid organic materials such as cellulosic materials, plastics or hydrocarbons. .
- At least two active products are placed inside the closed chamber containing the radioactive materials.
- active product A is designed to remove, by continuous catalytic oxidation by the oxygen present in the chamber, flammable gases, such as hydrogen, produced by radiolysis in the atmosphere of the enclosure, under the effect of radiation emitted by the radioactive isotopes present in said materials.
- active product B is an active product designed to continuously oxidise carbon monoxide and form CO 2 .
- a and B may optionally be associated with one or two other active products.
- active product C a third product, hereinafter referred to as “active product C”, designed to constitute a source of O 2 , making it possible to overcome the lack of oxygen once all the oxygen initially present in the pregnant was consumed; and a fourth product, hereinafter referred to as “active product D”, consisting of an active water-absorbing product.
- Active product A comprises a solid, preferably microporous, inert support which supports a precious metal (impregnated with a precious metal) such as palladium, platinum or rhodium.
- the solid inert carrier preferably microporous, may also support a rare earth (be impregnated with a rare earth) advantageously chosen from the group of lanthanides, such as lanthanum.
- the active product D is constituted by a microporous hygroscopic support.
- the inert solid support of the active product A when this support is microporous, and the hygroscopic microporous support of the optional active product D, are generally both constituted by a molecular sieve which has a large developed surface defined by a specific surface, for example greater than equal to 200, even 300 m 2 / g.
- the microporous support of the active product A when impregnated with a precious metal or a rare earth, it has a very high reaction surface. important for the oxidation of flammable gases produced by radiolysis in the atmosphere of the enclosure and more particularly hydrogen.
- the precious metal or the rare earth constitutes a catalyst for the continuous oxidation reaction of hydrogen by the oxygen contained in the chamber.
- the presence of less than 0.1% by weight of precious metal in the microporous catalyst support provides the desired effect.
- the preferred microporous inert support of the active product A and the microporous hygroscopic support of the active product D, if any, are generally constituted as indicated above by a molecular sieve preferably chosen with regard to the microporous support of the active product D in the group of silica-silicones.
- aluminates of formula Na 12 [(AlO 2 ) 12 (SiO 2 ) 12 ] XH 2 , where X can reach 27, which represents 28.5% of the anhydrous product, and as regards the microporous support of the active product A among the aluminas preferably activated.
- the large specific surface area of the preferred microporous support makes it possible to use at best the catalytic action of the precious metal or the rare earth. Indeed, a large reaction surface is produced on a support material, using little catalytic compound and in reduced volumes.
- the hydrogen In contact with the microporous inert support supporting the catalyst (impregnated with the catalyst), the hydrogen combines with the oxygen of the enclosure, to form water.
- the water thus formed is trapped and fixed deep in the micropores of the preferred support of the product A, by molecular capillarity.
- such a support can absorb up to 30% of its mass of water.
- any formation of free water is avoided, which could be decomposed again by radiolysis, restoring some of the hydrogen removed.
- the water trapped deep in microporous media is less subject to the effects of radiation emitted into the atmosphere of the chamber than if it were open water.
- the active product D is not present, the excess free water not absorbed by the catalyst support a) can then react with an active product C consisting of a solid peroxide to give a release of oxygen.
- the oxidation process thus implemented works perfectly because the atmosphere of the enclosure can not reach a high humidity level. More precisely, the effectiveness of the active product D makes it possible to guarantee a relative humidity of the enclosure environment of less than about 10%. This ensures a maximum yield of the oxidation reactions using the active products A and B.
- the active product B which is necessarily placed inside the enclosure, comprises a mixture metal oxides, preferably in the form of granules which allows the CO to be continuously removed by oxidation to CO 2 .
- a preferred product comprises a mixture of manganese dioxide MnO 2 and copper oxide CuO.
- the mixture of manganese dioxide MnO 2 and copper oxide CuO generally represents about 80% of the weight of product B (generally about 66% MnO 2 and 14% CuO).
- This active product B plays a particularly important role, when the gases in the chamber contain CO. Indeed, and without wishing to be bound by any theory, it was then demonstrated that the active sites of the active product A are blocked by the CO because the CO molecule is more cumbersome than the H 2 molecule. It is therefore the CO that is then converted preferentially by the catalyst a) and not hydrogen. In other words, the hydrogen is not recombined because the CO blocks the active sites of the catalyst a).
- a catalyst b) is placed inside the enclosure, the CO 2 is oxidized much faster than the catalyst a).
- the active sites of the catalyst a) are then more available to ensure the oxidation of flammable gases and in particular that of hydrogen.
- a catalyst which can be used as the active product B is the product sold under the name Carulite ® by ZANDER society. This is a mixture comprising CuO and MnO 2 which Specifically catalyzes the oxidation reaction of CO to CO 2 .
- the Carulite ® catalyzes this reaction, for example at a speed ten times greater, than does the catalyst), and therefore the catalyst a) still available for the oxidation reaction of combustible gases and in particular for the reaction oxidation of hydrogen into water.
- the mass ratio of the active product B of the active product A is generally from 1/1 to 1/10, preferably from 1/2 to 1/4. This ratio is generally determined for a ratio of CO flow rate to H 2 flow rate generally about 1/11; this flow ratio is that usually produced by technological waste.
- Active product C which is optional is defined as a source of oxygen.
- This source of oxygen is generally either in gaseous form or in solid form.
- This water is generally the water formed during the oxidation of hydrogen by the catalyst a) and which has not been absorbed by the solid inert carrier preferably microporous catalyst a).
- the active product C is such a solid peroxide
- the solid peroxide is generally selected from alkali and alkaline earth metal peroxides such as calcium peroxides, barium, sodium, potassium, magnesium and mixtures thereof.
- the source of oxygen in solid form is initially introduced into the chamber when a deficit of oxygen is expected.
- the active products A, B, C, D are generally in the form of discrete elements or particles, such as granules, beads, crystals.
- the microporous supports of the active products A, and optionally D are advantageously fractionated into small elements, particles, such as granules, beads or crystals.
- each of the elements of the microporous supports preferably has a shell diameter of between about 2 mm and about 20 mm.
- Each of said microporous support elements supports a (is impregnated with) a precious metal in the case of the active product A.
- the active product B is already generally in a fractionated form for example, namely generally in the form of granules of oxides MnO 2 and CuO.
- the active product C When it is present the active product C, if it is a solid product is generally in the form of powder.
- fractionation of the microporous supports optionally allows, as will be described more precisely below, to easily package at least one of the active products in various types of containers before placing them inside the enclosure.
- This fractionation also makes it possible to use the properties of the microporous support with maximum efficiency, by further increasing the oxidation surfaces of the support of the active product A.
- the hydrogen diffuses into the small elements forming the Microporous catalytic supports, it comes to oxidize around the surfaces of all these elements.
- the total oxidation surface corresponds to the sum of all the surfaces of the elements forming the support, which is much larger than the external surface of the overall volume occupied by said elements.
- the fractionation of the supports of the active product A and possibly D into small elements, the fractionality of the active products B and C and the use of microporous materials with a large specific surface area combine to provide the process according to the invention. a great efficiency. Hydrogen is efficiently oxidized over large areas, as is CO, and the water formed is trapped deep within the small elements, due to the capillary properties of the microporous materials, particularly the carrier material of the active product. D.
- the microporous support of the active products A is activated alumina Al 2 O 3 , packaged in small granules.
- Activated alumina Al 2 O 3 is a body with a large specific surface area greater than 200 m 2 per gram, or even 300 m 2 / g.
- the alumina granules have an envelope diameter of a few millimeters, preferably between about 2 mm and about 20 mm.
- the carrier of the active product A the granules are poorly impregnated with precious metal (less than 0.1% by weight) or rare earth.
- a quantity of granules impregnated with the activated product A corresponding to 1 liter by volume or about 800 g by weight is sufficient to remove more than 400 liters of hydrogen in the free atmosphere of a closed chamber.
- these are generally packaged in containers such as drums stowed inside the container.
- the active products are then advantageously placed inside these containers. This eliminates hydrogen directly where it is produced. Only a very small fraction of the hydrogen will then escape from the containers and will diffuse into the free volume of the container, where it will be removed by the active products, also arranged in small quantities in this free volume.
- the containers are waterproof, we can choose to have the active products in quantity sufficient only inside these receptacles. Indeed, the concentration of hydrogen in the atmosphere of the container will then always be insignificant since the hydrogen is removed in the containers and diffuse very little in the enclosure of the container.
- the introduction of the active products in the containers makes it possible to continue to prevent the accumulation of hydrogen after their final unloading.
- the active products may possibly be renewed to ensure the elimination of hydrogen continuously on the storage site.
- the use of the method according to the invention is not limited to the elimination of flammable gases produced in a closed enclosure during transport.
- the method according to the invention is particularly simple to use in combination with different types of enclosures containing radioactive materials comprising organic components and possibly water.
- the manipulations required to place active products inside the enclosure are particularly simple and quick to perform.
- the elimination of flammable gases produced by radiolysis inside the enclosure is effectively ensured.
- the transport and storage times can be managed in a very flexible way since it is sufficient to introduce inside the enclosure quantities of active products appropriate for the duration of transport and / or storage envisaged.
- the test is performed as follows:
- a quantity of active product a) described above equal to 25 grams and an amount of active product b) described above is placed in a 20 liter chamber (Tedlar bag) containing 600 ml of hydrogen and 53 ml of carbon monoxide. above equal to 12.5 g (the products are packaged separately).
- the initial hydrogen concentration is of the order of 5.6%.
- a mixture H 2 / CO is injected continuously with the following flow rates: 5.6 ml / h for the monoxide of carbon and 65 ml / h for hydrogen is a flow ratio H 2 / CO equal to 11.6.
- This report is representative of the ratio of H 2 and CO flows generated in a package containing compacted waste from the reprocessing of irradiated fuels (the average composition of which is 90% of hulls and end pieces and 10% of technological waste); the flow rates of hydrogen and carbon monoxide being respectively equal to 2 liters / hour and 0.18 liters / hour.
- the test lasted 95 hours (until the oxygen in the chamber was exhausted).
- the hydrogen content in the chamber is measured throughout the test by chromatography. This content remains below 1% (by volume) throughout the test as shown by the evolution curve of the H 2 content as a function of time (hours) given on the figure 1 .
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Abstract
Description
L'invention concerne un procédé et un dispositif destinés à éliminer des gaz inflammables, tels que de l'hydrogène, dans une enceinte fermée contenant des matières radioactives, en présence de composés organiques solides ou liquides et éventuellement d'eau susceptibles de produire de tels gaz, par radiolyse, ou lorsque les matières radioactives comprennent des composés de ce type et éventuellement de l'eau.The invention relates to a method and a device for eliminating flammable gases, such as hydrogen, in a closed chamber containing radioactive materials, in the presence of solid or liquid organic compounds and possibly water capable of producing such substances. gas, by radiolysis, or when the radioactive materials include such compounds and possibly water.
L'invention a trait également à une enceinte fermée telle qu'un récipient, réservoir, ou conteneur destiné au transport ou au stockage de matières radioactives en présence de composés organiques et éventuellement d'eau, ou comprenant des composants de ce type, ladite enceinte étant équipée d'un tel dispositif d'élimination des gaz inflammables.The invention also relates to a closed enclosure such as a container, tank, or container intended for the transport or storage of radioactive materials in the presence of organic compounds and possibly water, or comprising components of this type, said enclosure being equipped with such a flammable gas elimination device.
L'invention peut être utilisée dans toute enceinte fermée dans laquelle sont enfermées des matières radioactives renfermant des composés organiques et éventuellement de l'eau, ou des matières radioactives en présence de composés organiques et éventuellement d'eau. A titre d'exemple nullement limitatif, ces matières radioactives peuvent être des déchets technologiques en provenance d'un atelier de fabrication ou de traitement d'éléments combustibles destinés à un réacteur nucléaire ou issus d'un tel réacteur.The invention can be used in any closed chamber in which are enclosed radioactive materials containing organic compounds and optionally water, or radioactive materials in the presence of organic compounds and optionally water. By way of non-limiting example, these radioactive materials may be technological waste coming from a manufacture or treatment of fuel elements for a nuclear reactor or from such a reactor.
Les installations nucléaires telles que les ateliers de fabrication d'éléments combustibles destinés à des réacteurs nucléaires génèrent une certaine quantité de rebuts, dits "déchets technologiques". Ces déchets technologiques peuvent comprendre des objets et des matériaux de natures très diverses telles que des pièces de moteurs, des filtres, des déchets métalliques, des gravats, des verres, etc.... On y trouve également des matières organiques à base de cellulose comme du papier, du bois, du coton, ou sous forme de matières plastiques telles que des housses de conditionnement en vinyle ou en polyuréthanne, des bottes, des gants, et des objets divers en matériaux polymères. Tous ces déchets peuvent également renfermer de petites quantités de liquides tels que de l'eau et des liquides organiques (huiles, hydrocarbures, etc...). Tous ces déchets constituent en eux mêmes des matières radioactives, car ce sont des pièces de métal activées durant leur séjour dans les installations, ou des matières organiques ou autres contaminées par de la poudre d'uranium ou de plutonium radioactif lors de leur utilisation dans ces mêmes installations.Nuclear installations such as fuel element fabrication workshops for nuclear reactors generate a certain amount of waste, known as "technological waste". This technological waste can include objects and materials of very different natures such as engine parts, filters, scrap metal, rubble, glasses, etc. It also contains organic materials based on cellulose. such as paper, wood, cotton, or in the form of plastics such as vinyl or polyurethane packaging covers, boots, gloves, and miscellaneous objects of polymeric materials. All this waste can also contain small amounts of liquids such as water and organic liquids (oils, hydrocarbons, etc ...). All these wastes in themselves constitute radioactive materials, because they are metal parts activated during their stay in the facilities, or organic or other materials contaminated with uranium or radioactive plutonium powder when they are used in these facilities. same facilities.
Les déchets technologiques sont périodiquement évacués vers des centres de traitement et de stockage. Leur acheminement vers ces sites nécessite alors autant de précautions que le transport de toute autre matière radioactive. En particulier, les déchets doivent être conditionnés et transportés dans des conteneurs répondant aux prescriptions des règlements pour le transport de matières radioactives sur la voie publique.Technological waste is periodically evacuated to treatment and storage centers. Their routing to these sites then requires as many precautions as the transport of any other material radioactive. In particular, waste must be packaged and transported in containers meeting the requirements of the regulations for the transport of radioactive material on public roads.
Dans la pratique, les transports sont généralement effectués en conditionnant les déchets technologiques dans des récipients tels que des fûts, des poubelles ou des étuis, puis en plaçant ces récipients dans des conteneurs.In practice, transport is generally carried out by packaging the technological waste in containers such as drums, trash cans or cases and then placing these containers in containers.
Le transport des déchets technologiques pose une difficulté spécifique liée à la nature des matières transportées. En effet, comme on l'a vu précédemment, ces déchets contiennent souvent des matières organiques solides ou sous forme de liquides résiduels, ou encore une certaine quantité d'eau, contaminés par de l'uranium ou du plutonium qui confère à ces matières un caractère radioactif. Or, l'uranium et le plutonium sont des émetteurs de particules α qui ont notamment pour propriété de dissocier les molécules organiques pour libérer des composés gazeux tels que du monoxyde de carbone, du gaz carbonique, de l'oxygène et de l'azote, ainsi que des gaz inflammables. Ce phénomène, appelé "radiolyse", se traduit par une dissociation des molécules des composés organiques carbonés et hydrogénés tels que ceux qui sont contenus dans les matières plastiques et les hydrocarbures ou par une dissociation des molécules d'eau, avec production d'hydrogène.The transport of technological waste poses a specific difficulty related to the nature of the materials transported. Indeed, as we saw earlier, this waste often contains solid organic materials or in the form of residual liquids, or a certain amount of water, contaminated with uranium or plutonium which gives these materials a radioactive nature. However, uranium and plutonium are emitters of α particles which have the particular property of dissociating organic molecules to release gaseous compounds such as carbon monoxide, carbon dioxide, oxygen and nitrogen, as well as flammable gases. This phenomenon, called "radiolysis", results in a dissociation of molecules of carbon and hydrogenated organic compounds such as those contained in plastics and hydrocarbons or by a dissociation of water molecules, with production of hydrogen.
La production de gaz inflammables et notamment d'hydrogène par radiolyse pose principalement des problèmes lorsque les déchets technologiques sont confinés dans une enceinte fermée de volume relativement limité. En effet, les gaz de radiolyse sont alors libérés dans un volume confiné, de telle sorte qu'on peut atteindre rapidement une concentration élevée en gaz inflammables si la nature des déchets et l'intensité des radiations conduisent à une production importante de ces gaz.The production of flammable gases, particularly hydrogen by radiolysis, mainly problems when technological waste is confined in a closed enclosure of relatively limited volume. In effect, the radiolysis gases are then released in a confined volume, so that a high concentration of flammable gases can be reached rapidly if the nature of the waste and the intensity of the radiation lead to a large production of these gases.
Ce problème est particulièrement critique lors du transport, du fait qu'on place alors généralement un nombre important de récipients de déchets dans un même conteneur, afin d'optimiser la capacité de transport. En effet, cela a pour conséquence de réduire l'espace libre disponible dans le conteneur pour les gaz inflammables qui s'échappent des déchets et des récipients.This problem is particularly critical during transport, because then a large number of waste containers are usually placed in the same container, in order to optimize the transport capacity. Indeed, this has the effect of reducing the free space available in the container for flammable gases that escape waste and containers.
On peut observer également que les récipients de conditionnement des déchets présentent souvent eux-mêmes une certaine étanchéité, du fait qu'ils sont fermés par des couvercles sertis pouvant être munis de joints d'étanchéité. Dans ce cas, les gaz inflammables s'accumulent préférentiellement dans l'espace libre résiduel existant à l'intérieur de chacun des récipients. Du fait que ces volumes sont également très réduits, cela peut conduire à des concentrations importantes de gaz inflammables dans les récipients de conditionnement eux-mêmes.It can also be seen that the waste containers often themselves have a certain tightness, because they are closed by crimped lids that can be provided with gaskets. In this case, the flammable gases preferentially accumulate in the residual free space existing inside each of the containers. Because these volumes are also very small, this can lead to significant concentrations of flammable gases in the packaging containers themselves.
De façon générale, les gaz inflammables produits par radiolyse constituent un mélange détonnant lorsqu'ils sont mis en présence d'autres gaz tels que l'air, lorsque leur concentration dépasse une valeur limite, dite "seuil d'inflammabilité". Le seuil d'inflammabilité est variable selon la nature du gaz inflammable et selon les conditions de température et de pression. Dans le cas de l'hydrogène, le seuil d'inflammabilité dans l'air est situé autour de 4%. Cela signifie que, lorsque la concentration en hydrogène dans l'air dépasse ce seuil, une source de chaleur ou une étincelle peut suffire à enflammer le mélange ou à produire une déflagration violente dans une enceinte confinée.In general, flammable gases produced by radiolysis are an explosive mixture when they are in contact with other gases such as air, when their concentration exceeds a certain value. limit, known as the "flammability threshold". The flammability threshold is variable depending on the nature of the flammable gas and the temperature and pressure conditions. In the case of hydrogen, the flammability threshold in air is around 4%. This means that when the concentration of hydrogen in the air exceeds this threshold, a source of heat or a spark may be sufficient to ignite the mixture or to produce a violent explosion in a confined space.
Diverses études et observations ont montré que la concentration des gaz inflammables tels que l'hydrogène, produits par radiolyse dans une enceinte fermée contenant des matières radioactives comportant des composants hydrogénés, peut parfois atteindre des valeurs d'environ 4% au bout de quelques jours. Cette situation correspond notamment au cas où les déchets technologiques émettent des particules α intenses et contiennent de nombreuses molécules organiques.Various studies and observations have shown that the concentration of flammable gases such as hydrogen, produced by radiolysis in a closed chamber containing radioactive material containing hydrogenated components, can sometimes reach values of about 4% after a few days. This situation corresponds in particular to the case where technological waste emits intense α particles and contains numerous organic molecules.
Or, il est courant qu'un conteneur reste fermé pour des durées beaucoup plus longues avant d'être ouvert. Il y a alors risque d'accident, du fait qu'une étincelle occasionnée par des chocs ou des frottements peut se produire en cours de transport dans l'enceinte du conteneur ou dans un récipient rempli de déchets. Dans une telle hypothèse, l'inflammation ou l'explosion risque de s'étendre à l'ensemble du chargement du conteneur, ce qui se traduit par un risque d'accident grave sur la voie publique. Un risque comparable existe si le conteneur se trouve pris dans une situation accidentelle d'incendie durant son transport. De plus, le risque d'accident subsiste lors des opérations finales d'ouverture du conteneur et de déchargement des récipients, et lors de leur ouverture éventuelle. En effet, ces opérations nécessitent de nombreuses manipulations, alors potentiellement dangereuses. Il est donc particulièrement important de prendre en compte le risque d'accumulation de gaz inflammables dans toute enceinte fermée appelée à contenir des matières radioactives comportant des composés hydrogénés.However, it is common for a container to remain closed for much longer periods before being opened. There is a risk of accident, because a spark caused by shocks or friction can occur during transport in the enclosure of the container or in a container filled with waste. In such a case, the ignition or explosion may spread to the entire load of the container, which results in a risk of serious accident on public roads. A comparable risk exists if the container is caught in an accidental fire situation during transport. Moreover, the risk of accidents remains during the final operations of opening the container and unloading the containers, and when they are opened. Indeed, these operations require many manipulations, then potentially dangerous. It is therefore particularly important to take into account the risk of accumulation of flammable gases in any closed enclosure called to contain radioactive materials containing hydrogenated compounds.
Une technique pour éliminer les gaz inflammables tels que l'hydrogène se trouvant à l'intérieur d'une enceinte fermée tel qu'un conteneur de transport de déchets radioactifs est basée essentiellement sur l'introduction dans l'enceinte d'un catalyseur de recombinaison de l'oxygène et de l'hydrogène en eau (ou recombineur catalytique d'hydrogène), au contact duquel l'hydrogène se combine avec l'oxygène présent dans l'air de la cavité pour former de l'eau suivant le mécanisme d'oxydation catalytique de l'hydrogène.A technique for removing flammable gases such as hydrogen located inside a closed enclosure such as a radioactive waste transport container is based essentially on the introduction into the chamber of a recombination catalyst oxygen and hydrogen in water (or catalytic recombinant hydrogen), in contact with which hydrogen combines with the oxygen present in the air cavity to form water according to the mechanism of catalytic oxidation of hydrogen.
Des dispositifs mettant en oeuvre cette technique sont décrits par exemple dans les documents
Le document
L'hydrogène qui s'est formé dans le récipient de stockage traverse la bougie en métal fritté et arrive sur le catalyseur où l'hydrogène est oxydé en eau par l'oxygène de l'air.The hydrogen that has formed in the storage vessel passes through the sintered metal candle and arrives on the catalyst where the hydrogen is oxidized into water by the oxygen in the air.
Le catalyseur utilisé comprend un métal précieux par exemple du palladium sur un support inerte par exemple en alumine.The catalyst used comprises a precious metal, for example palladium on an inert support, for example alumina.
On fait appel dans ce document à une source extérieure d'oxygène constituée par l'air ambiant ce qui ne peut être envisagé pour des enceintes fermées, hermétiques, des emballages parfaitement étanches.In this document, an external source of oxygen constituted by the ambient air is used, which can not be envisaged for closed, hermetic enclosures or perfectly sealed packages.
Le document
A l'intérieur de l'enveloppe sont prévues deux feuilles de séparation perméables à la vapeur d'eau en dessous desquelles sont disposées deux couches d'agent dessicant.Inside the casing are provided two vapor-permeable separation sheets below which two layers of desiccant are arranged.
Dans une première forme de réalisation, au-dessus de la feuille de séparation se trouvent deux grilles supportant le catalyseur de recombinaison.In a first embodiment, above the separation sheet are two grids supporting the recombination catalyst.
Dans une deuxième forme de réalisation, au-dessus de la feuille de séparation, se trouve une couche d'un agent oxydant qui est maintenue en place par une feuille de séparation perméable aux gaz.In a second embodiment, above the separator sheet is a layer of an oxidizing agent which is held in place by a gas permeable separator sheet.
L'agent dessicant est choisi par exemple parmi le gel de silice, les tamis moléculaires, les agents complexants déshydratés tels que par exemple le sulfate de cuivre ou les produits chimiques hygroscopiques tels que le chlorure de calcium, le sulfate de magnésium, ou le pentoxyde de phosphore, éventuellement sur un matériau support.The desiccant is chosen for example from silica gel, molecular sieves, dehydrated complexing agents such as, for example, copper sulphate or hygroscopic chemicals such as calcium chloride, magnesium sulphate, or pentoxide. phosphorus, optionally on a support material.
Le catalyseur de recombinaison est choisi en particulier parmi les catalyseurs enrobés de platine ou de palladium. Dans ce dispositif, le recombineur devient inopérant une fois que tout l'oxygène de l'enceinte a été consommé.The recombination catalyst is chosen in particular from platinum or palladium-coated catalysts. In this device, the recombiner becomes inoperative once all the oxygen in the chamber has been consumed.
Il a en outre été constaté que ces dispositifs et procédés, qui mettent en oeuvre des recombineurs catalytiques d'hydrogène ont en commun de présenter une efficacité réduite dans le cas notamment où l'enceinte contenait des composés organiques carbonés.It has furthermore been found that these devices and processes, which use catalytic hydrogen recombiners, have in common a reduced efficiency in the case in particular where the enclosure contained organic carbon compounds.
Le document
Il existe donc un besoin pour un procédé et un dispositif qui permettent d'éliminer les gaz inflammables, et notamment l'hydrogène, dans une enceinte fermée contenant des matières radioactives comprenant des composés organiques quelle que soit la nature de ceux-ci et leur teneur en carbone, et éventuellement de l'eau.There is therefore a need for a method and a device which makes it possible to eliminate flammable gases, and in particular hydrogen, in a closed chamber containing radioactive materials comprising organic compounds whatever the nature of these and their content. carbon, and possibly water.
Il existe aussi un besoin pour un procédé et un dispositif d'élimination des gaz inflammables dans une enceinte fermée qui permettent d'assurer l'élimination des gaz inflammables, en particulier de l'hydrogène sur une longue durée, voire une durée pratiquement illimitée.There is also a need for a method and a device for the elimination of flammable gases in a closed chamber which make it possible to ensure the elimination of flammable gases, in particular hydrogen for a long period, or even a practically unlimited duration.
Il existe encore un besoin pour un procédé et un dispositif d'élimination des gaz inflammables dans une enceinte fermée qui soit simple, fiable, sûr, facile à mettre en oeuvre, qui ne fasse pas appel à des procédures longues et coûteuses et qui assure une élimination efficace des gaz inflammables tels que l'hydrogène dans une grande diversité de conditions, à savoir entre autres :
- en présence d'autres gaz de radiolyse tels que les oxydes comme le monoxyde de carbone et le dioxyde de carbone,
- sous irradiation et quelle que soit le type et l'intensité de cette radiation,
- à différentes températures, ces températures pouvant être négatives.
- in the presence of other radiolysis gases such as oxides such as carbon monoxide and carbon dioxide,
- under irradiation and whatever the type and intensity of this radiation,
- at different temperatures, these temperatures may be negative.
Le but de l'invention est de fournir un procédé et un dispositif qui répondent entre autres à l'ensemble des besoins énumérés plus haut.The object of the invention is to provide a method and a device that meet, among others, all the needs listed above.
Le but de l'invention est encore de fournir un procédé et un dispositif qui ne présentent pas les inconvénients, limitations, défauts et désavantages des procédés et dispositifs de l'art antérieur et qui apportent une solution aux problèmes posés par les procédés et dispositifs de l'art antérieur, tels que ceux décrits dans les documents
Ce but et d'autres encore sont atteints conformément à l'invention, par un procédé d'élimination des gaz inflammables produits par radiolyse dans une enceinte fermée et les gaz inflammables réagissent avec l'oxygène contenu dans l'atmosphère de l'enceinte, cette réaction d'oxydation des gaz inflammables étant catalysée par le premier catalyseur contenant des matières radioactives comprenant des composés organiques et éventuellement de l'eau, ou des matières radioactives se trouvant en présence de composés organiques et éventuellement d'eau, dans lequel on place à l'intérieur de l'enceinte :
- a) un premier catalyseur d'au moins une réaction d'oxydation des gaz inflammables par de l'oxygène contenu dans l'atmosphère de l'enceinte, supporté par un support inerte solide;
- b) un deuxième catalyseur d'au moins la réaction d'oxydation de CO en CO2; qui est un récipient, réservoir ou conteneur, destiné au transport et/ou au stockage de matières radioactives, ladite enceinte fermée.
- a) a first catalyst of at least one oxidation reaction of the flammable gases by oxygen contained in the atmosphere of the chamber, supported by a solid inert support;
- b) a second catalyst of at least the oxidation reaction of CO to CO 2 ; which is a container, tank or container, intended for the transport and / or storage of radioactive materials, said enclosure closed.
La réaction d'oxydation des gaz inflammables par l'oxygène contenu dans l'atmosphère de l'enceinte est généralement, essentiellement, une réaction d'oxydation de l'hydrogène en eau.The oxidation reaction of the flammable gases by the oxygen contained in the chamber atmosphere is generally, essentially, a reaction of oxidation of hydrogen into water.
De préférence, le catalyseur a) est un catalyseur d'au moins la réaction d'oxydation de l'hydrogène en eau.Preferably, the catalyst a) is a catalyst for at least the oxidation reaction of hydrogen in water.
Le catalyseur a) supporté par un support solide inerte constitue un premier produit actif qui permet l'élimination en continu des gaz inflammables, et en particulier de l'hydrogène, produit par radiolyse des molécules, composés organiques et éventuellement de l'eau à l'intérieur de l'enceinte.The catalyst a) supported by an inert solid support constitutes a first active product which allows the continuous removal of flammable gases, and in particular hydrogen, produced by radiolysis of the molecules, organic compounds and optionally water at room temperature. inside the enclosure.
Cette élimination est assurée par la réaction d'oxydation des gaz inflammables avec l'oxygène contenu dans l'atmosphère de l'enceinte, et notamment par la réaction de recombinaison de l'hydrogène avec l'oxygène de l'atmosphère de l'enceinte pour donner de l'eau.This elimination is ensured by the oxidation reaction of the flammable gases with the oxygen contained in the chamber atmosphere, and in particular by the recombination reaction of the hydrogen with the oxygen of the chamber atmosphere. to give water.
Le catalyseur a) de cette réaction d'oxydation, qui est supporté par un support solide inerte, peut être un métal précieux qui est avantageusement choisi dans le groupe constitué par le platine, le palladium, et le rhodium.Catalyst a) of this oxidation reaction, which is supported by an inert solid support, may be a precious metal which is advantageously selected from the group consisting of platinum, palladium, and rhodium.
Le métal précieux est présent dans une quantité qui est généralement inférieure à 0,1% en poids.The precious metal is present in an amount which is generally less than 0.1% by weight.
Ou bien le catalyseur a) de cette réaction d'oxydation peut être une terre rare, choisie avantageusement dans le groupe des lanthanides tels que le lanthane.Either the catalyst a) of this oxidation reaction may be a rare earth, advantageously chosen from the group of lanthanides such as lanthanum.
Le support du catalyseur a) est un support solide inerte.The catalyst support a) is an inert solid support.
Par support inerte, on entend un support ne réagissant chimiquement pas avec les composés se trouvant dans l'enceinte, l'atmosphère de celle-ci, et les autres produits actifs.By inert support is meant a support which does not react chemically with the compounds in the enclosure, the atmosphere thereof, and the other active products.
De préférence, le support du catalyseur a) est un support inerte solide microporeux.Preferably, the catalyst support a) is a microporous solid inert carrier.
Ce support microporeux est choisi généralement parmi les tamis moléculaires éventuellement activés.This microporous support is generally chosen from the optionally activated molecular sieves.
Le terme activé est un terme couramment utilisé dans ce domaine de la technique, qui signifie que le composé formant le tamis moléculaire tel que l'alumine a subi un traitement notamment thermique afin, en particulier, d'augmenter sa surface spécifique.The term activated is a term commonly used in this field of the art, which means that the compound forming the molecular sieve such as alumina has undergone a particular thermal treatment in particular, to increase its specific surface area.
Ce tamis moléculaire est de préférence en un matériau choisi parmi les alumines et les alumines activées.This molecular sieve is preferably a material selected from aluminas and activated aluminas.
Le support solide, inerte, microporeux a généralement une surface spécifique élevée, à savoir une surface spécifique généralement d'au moins 200 m2/g, de préférence d'au moins 300 m2/g.The solid, inert, microporous support generally has a high specific surface area, ie a surface area generally of at least 200 m 2 / g, preferably at least 300 m 2 / g.
Le catalyseur b) constitue un deuxième produit actif, il catalyse la réaction d'oxydation du CO en CO2. De préférence, le catalyseur b) est un catalyseur spécifique de la réaction d'oxydation du CO en CO2.The catalyst b) comprises a second active product, it catalyses the oxidation reaction of CO to CO 2. Preferably, catalyst b) is a specific catalyst for the CO 2 oxidation reaction in CO 2 .
Par spécifique, on entend que la cinétique d'oxydation du CO en CO2 catalysée par b) est bien plus grande que celle catalysée par a).By specific is meant that the oxidation kinetics of CO 2 CO 2 catalysed by b) is much greater than that catalyzed by a).
De préférence, le catalyseur b) comprend un mélange de dioxyde de manganèse MnO2 et d'oxyde de cuivre CuO.Preferably, catalyst b) comprises a mixture of manganese dioxide MnO 2 and copper oxide CuO.
Le procédé selon l'invention met en oeuvre une combinaison de deux produits actifs, catalyseurs spécifiques a) et b) qui n'a jamais été décrite dans l'art antérieur tel que représenté notamment par les documents
Le procédé selon l'invention du fait, essentiellement, de l'utilisation d'une telle combinaison spécifique de produits actifs, catalyseurs a) et b), répond aux besoins et exigences énumérés plus haut et apporte une solution aux problèmes posés par les procédés de l'art antérieur. En particulier, les inventeurs ont pu mettre en évidence que l'efficacité des procédés de l'art antérieur est fortement réduite en présence d'autres gaz de radiolyse tels que le monoxyde de carbone CO ; cette diminution d'efficacité s'explique par un empoisonnement du catalyseur d'oxydation de l'H2 (a)) tel que le palladium, par le monoxyde de carbone CO.The process according to the invention essentially because of the use of such a specific combination of active products, catalysts a) and b), meets the needs and requirements listed above and provides a solution to the problems posed by the processes. of the prior art. In particular, the inventors have been able to demonstrate that the efficiency processes of the prior art are greatly reduced in the presence of other radiolysis gases such as carbon monoxide CO; this decrease in efficiency is explained by a poisoning of the oxidation catalyst of H 2 (a)) such as palladium, by CO carbon monoxide.
De ce fait, en associant au catalyseur d'oxydation des gaz inflammables un catalyseur b) de la réaction du CO en CO2, on parvient de manière surprenante à éviter l'empoisonnement du catalyseur a) d'oxydation des gaz inflammables par le CO. Le catalyseur b) assure l'élimination en continu du monoxyde de carbone, par oxydation, pour donner du gaz carbonique qui ne cause aucun problème d'empoisonnement du catalyseur a).Therefore, by associating with the oxidation catalyst flammable gases a catalyst b) the CO 2 CO 2 reaction, it is surprisingly possible to avoid the poisoning of the catalyst a) oxidation of flammable gases by CO . Catalyst b) ensures the continuous removal of carbon monoxide, by oxidation, to give carbon dioxide which causes no problem of poisoning catalyst a).
Rien ne pouvait laisser soupçonner dans l'art antérieur que la baisse de l'efficacité du catalyseur provenait fondamentalement de la présente de CO dans l'enceinte. Il n'existait aucun indice dans l'art antérieur qui aurait conduit l'homme du métier à associer au catalyseur a), tel qu'un recombineur, couramment utilisé dans ce domaine de la technique, un catalyseur spécifique b).There was nothing to suggest in the prior art that the decrease in catalyst efficiency was basically due to the presence of CO in the chamber. There was no indication in the prior art that would have led the skilled person to associate with catalyst a), such as a recombiner, commonly used in this field of the art, a specific catalyst b).
Le procédé selon l'invention permet d'éliminer efficacement, sur une très longue durée, voire une durée quasiment illimitée, les gaz inflammables tels que l'hydrogène, contenus dans l'enceinte fermée. Il conserve une très grande efficacité quels que soient les déchets contenus dans l'enceinte et notamment lorsque les déchets contiennent des composés organiques carbonés et hydrogénés susceptibles de libérer à la fois du CO et de l'hydrogène. Le procédé selon l'invention fonctionne parfaitement en présence de gaz de radiolyse divers qui sont outre l'hydrogène, par exemple le CO, le CO2, etc....The method according to the invention makes it possible to effectively remove, over a very long time, or even a virtually unlimited duration, flammable gases such as hydrogen, contained in the closed chamber. It retains a high degree of efficiency irrespective of the waste contained in the enclosure and in particular when the waste contains organic carbon and hydrogen compounds capable of releasing both CO and hydrogen. The process according to the invention functions perfectly in the presence of various radiolysis gases which are in addition to hydrogen, for example CO, CO 2 , etc.
Le procédé selon l'invention fonctionne de même parfaitement dans une large gamme de température et en particulier à des températures négatives et sous irradiation quelle que soit la nature de celle-ci.The process according to the invention likewise functions perfectly in a wide range of temperatures and in particular at negative temperatures and under irradiation whatever the nature of the latter.
Eventuellement, on place à l'intérieur de l'enceinte, outre les deux catalyseurs a) et b) qui sont toujours présents, une source d'oxygène c). Cette source d'oxygène constitue un troisième produit actif facultatif qui permet de pallier au manque d'oxygène, une fois que tout l'oxygène initialement présent dans l'enceinte a été consommé.Optionally, there is placed inside the enclosure, in addition to the two catalysts a) and b) which are always present, a source of oxygen c). This source of oxygen is a third optional active product that makes it possible to overcome the lack of oxygen, once all the oxygen initially present in the chamber has been consumed.
Cette source d'oxygène peut être soit sous forme gazeuse soit sous forme solide.This source of oxygen can be either in gaseous form or in solid form.
Dans le cas où la source d'oxygène est sous forme solide, elle est généralement choisie parmi les peroxydes solides. Ces composés libèrent de l'oxygène en présence d'eau qui est par exemple l'eau formée au cours de l'oxydation de l'hydrogène par le catalyseur a). Ces peroxydes solides sont généralement choisis parmi les peroxydes des métaux alcalins et alcalino-terreux et leurs mélanges tels que le peroxyde de calcium, le peroxyde de baryum, le peroxyde de sodium, le peroxyde de potassium, le peroxyde de magnésium et leurs mélanges.In the case where the oxygen source is in solid form, it is generally chosen from solid peroxides. These compounds release oxygen in the presence of water which is for example the water formed during the oxidation of hydrogen by the catalyst a). These solid peroxides are generally selected from alkali and alkaline earth metal peroxides and mixtures thereof such as calcium peroxide, barium peroxide, sodium peroxide, potassium peroxide, magnesium peroxide and mixtures thereof.
Dans le cas où la source d'oxygène est sous forme gazeuse, elle est généralement formée en remplaçant tout ou partie de l'atmosphère de l'enceinte par de l'oxygène pur.In the case where the oxygen source is in gaseous form, it is generally formed in replacing all or part of the atmosphere of the enclosure with pure oxygen.
Eventuellement, on place en outre à l'intérieur de l'enceinte un support solide inerte microporeux hygroscopique d).Optionally, a microporous hygroscopic inert solid support d) is also placed inside the enclosure.
Le support solide inerte microporeux hygroscopique constitue un quatrième produit actif facultatif, permettant d'assurer en continu l'abaissement du degré hygrométrique de l'atmosphère de l'enceinte, par adsorption d'eau. En fonction de la température, la quantité d'eau éliminée représente généralement de 15% à 30% du poids du support microporeux hygroscopique. L'humidité résiduelle à l'intérieur de l'enceinte est ainsi maintenue à une valeur faible par exemple inférieure à 10% (taux d'hygrométrie) jusqu'à saturation dudit support. Celui-ci permet notamment de capter l'eau libre produite par la réaction d'oxydation, en particulier de l'hydrogène, catalysée par le catalyseur a) et qui n'aurait pas été absorbée dans les micropores du support solide, tel que de l'alumine, du catalyseur a) qui peut absorber généralement jusqu'à 30% de sa masse en eau.The hygroscopic microporous inert solid support constitutes a fourth optional active product, making it possible to continuously ensure the lowering of the hygrometric degree of the atmosphere of the enclosure, by adsorption of water. Depending on the temperature, the amount of water removed generally represents from 15% to 30% of the weight of the microporous hygroscopic support. The residual moisture inside the chamber is thus kept at a low value, for example less than 10% (humidity level) until saturation of said support. This allows in particular to capture the free water produced by the oxidation reaction, in particular hydrogen, catalyzed by the catalyst a) and which would not have been absorbed in the micropores of the solid support, such as alumina, catalyst a) which can generally absorb up to 30% of its mass in water.
Le support microporeux hygroscopique, est de préférence choisi parmi les tamis moléculaires.The hygroscopic microporous support is preferably chosen from molecular sieves.
Avantageusement, le tamis moléculaire du support solide inerte microporeux d) est en un matériau choisi parmi les matériaux de type silico-aluminate, par exemple de formule Na12 [(AℓO2)12(SiO2)12] X H2O, avec X pouvant atteindre 27, soit 28,5% en poids du produit anhydre.Advantageously, the molecular sieve of the microporous inert solid support d) is made of a material chosen from silico-aluminate type materials, for example of formula Na 12 [(AℓO 2 ) 12 (SiO 2 ) 12] XH 2 O, with X up to 27, or 28.5% by weight of the anhydrous product.
Le support microporeux hygroscopique a généralement une surface spécifique élevée, à savoir d'au moins 200 m2/g, de préférence d'au moins 300 m2/g.The hygroscopic microporous support generally has a high specific surface area, i.e. at least 200 m 2 / g, preferably at least 300 m 2 / g.
Il est à noter que ce quatrième produit actif est notamment présent dans le cas où le troisième produit actif est constitué par une source d'oxygène gazeuse. En effet, dans ce cas, la présence d'eau qui n'aurait pas été absorbée par le support du catalyseur a) tel que l'alumine, n'est pas nécessaire pour générer de l'oxygène, au contraire du cas où la source d'oxygène est constituée par un peroxyde solide qui libère de l'oxygène seulement en présence d'eau.It should be noted that this fourth active product is particularly present in the case where the third active product is constituted by a source of gaseous oxygen. Indeed, in this case, the presence of water that would not have been absorbed by the catalyst support a) such as alumina, is not necessary to generate oxygen, contrary to the case where the Oxygen source consists of a solid peroxide that releases oxygen only in the presence of water.
De préférence, le support microporeux inerte solide supportant le catalyseur a) ; le catalyseur b) ; et éventuellement la source d'oxygène c) et le support microporeux hygroscopique d) se présentent sous la forme d'éléments discrets, de particules, tels que par exemple des cristaux, des billes ou des granules formant éventuellement une poudre.Preferably, the solid inert microporous support supporting the catalyst a); catalyst b); and optionally the oxygen source c) and the microporous hygroscopic support d) are in the form of discrete elements, particles, such as for example crystals, beads or granules optionally forming a powder.
Ainsi dans un mode de réalisation préféré de l'invention, le support, inerte solide, de préférence microporeux, supportant le catalyseur a) ; le catalyseur b) ; et le support microporeux hygroscopique d) éventuel, sont fractionnés en éléments discrets, tels que par exemple des cristaux, des billes ou des granules, ayant un diamètre enveloppe généralement compris entre environ 2 mm et environ 20 mm.Thus, in a preferred embodiment of the invention, the solid inert carrier, preferably microporous, supporting the catalyst a); catalyst b); and the hygroscopic microporous support d), if any, are fractionated into discrete elements, such as for example crystals, beads or granules, having an envelope diameter generally of between about 2 mm and about 20 mm.
L'expression "diamètre enveloppe" désigne le diamètre d'une sphère fictive constituant l'enveloppe dudit élément.The expression "envelope diameter" designates the diameter of a fictional sphere constituting the envelope of said element.
Le produit actif c) est avantageusement sous une forme finement divisée telle qu'une poudre.The active product c) is advantageously in a finely divided form such as a powder.
De façon générale, les produits actifs a), b) et éventuellement c) et d) sont placés, mélangés ou séparément, dans au moins un récipient, au moins partiellement perméable, tel qu'une enveloppe textile, une crépine, un grillage métallique, ou un récipient percé de trous, tel qu'une cartouche.In general, the active products a), b) and optionally c) and d) are placed, mixed or separately, in at least one container, at least partially permeable, such as a textile envelope, a strainer, a wire mesh , or a container pierced with holes, such as a cartridge.
De préférence, les produits actifs a) et b) sont mélangés.Preferably, the active products a) and b) are mixed.
En revanche, les produits actifs c) et d) doivent être séparés.On the other hand, active products c) and d) must be separated.
On pourra par exemple disperser chacun des produits actifs entre deux grillages sous la forme de couches superposées ou former une seule couche avec un mélange des deux produits actifs obligatoires a) et b), chacun des produits actifs facultatifs c) et d) étant conditionné séparément par exemple sous la forme de couches séparées.For example, each of the active products can be dispersed between two screens in the form of superposed layers or form a single layer with a mixture of the two mandatory active products a) and b), each of the optional active products c) and d) being separately packaged. for example in the form of separate layers.
On peut placer plusieurs récipients tels que des cartouches à l'intérieur d'une même enceinte fermée afin d'augmenter la surface d'échange.Several containers such as cartridges can be placed inside the same closed chamber in order to increase the exchange surface.
Le rapport massique entre le catalyseur b) et le catalyseur a) est généralement de 1/1 à 1/10, de préférence de 1/2 à 1/4, ce rapport massique étant généralement donné pour un rapport du débit de CO sur le débit de H2 généralement d'environ 1:11.The mass ratio between the catalyst b) and the catalyst a) is generally from 1/1 to 1/10, preferably from 1/2 to 1/4, this mass ratio being generally given for a ratio of the flow rate of CO on the flow rate of H 2 generally about 1:11.
L'invention concerne également un dispositif d'élimination de gaz inflammables produits par radiolyse dans une enceinte fermée qui est un récipient, réservoir ou conteneur, destiné au transport et/ou au stockage de matières radioactives, ladite enceinte, fermée contenant des matières radioactives comprenant des composés organiques et éventuellement de l'eau, ou des matières radioactives se trouvant en présence de composés organiques et éventuellement d'eau, comprenant :
- a) un catalyseur d'au moins une réaction d'oxydation des gaz inflammables par de l'oxygène contenu dans l'atmosphère de l'enceinte, supporté par un support inerte solide ;
- b) un catalyseur d'au moins la réaction d'oxydation de CO en CO2 ;
- a) a catalyst for at least one oxidation reaction of the flammable gases by oxygen contained in the atmosphere of the enclosure, supported by a solid inert support;
- b) a catalyst of at least the oxidation reaction of CO to CO 2 ;
Enfin, l'invention concerne également une enceinte fermée, qui est un récipient, réservoir ou conteneur, destiné au transport et/ou au stockage de matières radioactives, ladite enceinte fermée étant apte à contenir des matières radioactives comprenant des composés organiques et éventuellement de l'eau, ou des matières radioactives se trouvant en présence de composés organiques et éventuellement d'eau, susceptibles de produire des gaz inflammables, par radiolyse, ladite enceinte contenant de plus au moins un dispositif d'élimination des gaz inflammables tel que défini précédemment.Finally, the invention also relates to a closed enclosure, which is a container, tank or container, intended for the transport and / or storage of radioactive materials, said closed enclosure being capable of containing radioactive materials comprising organic compounds and optionally water, or radioactive materials in the presence of organic compounds and possibly water, capable of producing flammable gases, by radiolysis, said enclosure further containing at least one flammable gas elimination device as defined above.
L'invention sera mieux comprise à la lecture de la description détaillée qui va suivre donnée à titre illustratif et non limitatif en référence aux dessins joints dans lesquels :
- La
figure 1 est un graphique qui donne la teneur en hydrogène (en % en volume), dans l'enceinte, mesurée par chromatographie, en fonction du temps (t en heures) lors de l'essai réalisé dans l'exemple.
- The
figure 1 is a graph that gives the hydrogen content (in% by volume) in the chamber, measured by chromatography, as a function of time (t in hours) during the test carried out in the example.
L'invention s'applique à toute enceinte fermée, dans laquelle sont placées des matières radioactives qui comprennent des composés organiques et éventuellement de l'eau, ou des matières radioactives qui se trouvent en présence de composés organiques et éventuellement d'eau.The invention applies to any closed enclosure, in which are placed radioactive materials which comprise organic compounds and possibly water, or radioactive materials which are in the presence of organic compounds and optionally water.
Par composé organique, on entend au sens de l'invention un composé comprenant au moins un atome de carbone, au moins un atome d'hydrogène et éventuellement au moins un autre atome choisi par exemple parmi les atomes d'azote, soufre, phosphore, oxygène, et halogènes.For the purposes of the invention, the term "organic compound" means a compound comprising at least one carbon atom, at least one hydrogen atom and optionally at least one other atom chosen, for example, from nitrogen, sulfur or phosphorus atoms. oxygen, and halogens.
Cette enceinte peut présenter une forme et des dimensions quelconques, ainsi qu'un niveau d'étanchéité plus ou moins grand, sans sortir du cadre de l'invention. Il peut notamment s'agir d'un récipient tel qu'un fût ou d'un conteneur de forme cylindrique ou parallélépipédique. Par ailleurs, l'enceinte peut être destinée indifféremment au transport, au stockage ou au traitement des matières radioactives concernées.This enclosure may have any shape and dimensions, and a level of sealing greater or less, without departing from the scope of the invention. It may especially be a container such as a drum or a container of cylindrical or parallelepiped shape. Moreover, the enclosure can be indifferently for the transport, storage or treatment of the radioactive material concerned.
Par ailleurs, les matières radioactives placées dans l'enceinte fermée peuvent être constituées par toutes les matières radioactives comprenant des composés organiques et éventuellement de l'eau, ou par toutes les matières radioactives se trouvant en présence de composés organiques et éventuellement d'eau.Furthermore, the radioactive materials placed in the closed chamber may be constituted by all the radioactive materials comprising organic compounds and possibly water, or by all the radioactive materials in the presence of organic compounds and possibly water.
De manière générale, l'invention s'applique plus particulièrement au cas où lesdits composés organiques sont des composés qui en plus de l'hydrogène émettent, produisent du CO et du CO2 tels que certaines matières plastiques. En effet, on a mis en évidence selon l'invention que le CO empoisonne le catalyseur a) et pouvait être éliminé efficacement par le catalyseur b) pour préserver l'efficacité du catalyseur a).In general, the invention applies more particularly to the case where said compounds Organic compounds are compounds that in addition to hydrogen emit, produce CO and CO 2 such as certain plastics. Indeed, it has been demonstrated according to the invention that the CO poisons the catalyst a) and can be effectively removed by the catalyst b) to preserve the effectiveness of the catalyst a).
A titre d'exemple nullement limitatif, les matières radioactives peuvent être constituées par des déchets technologiques en provenance d'une usine destinée au traitement ou à la fabrication d'éléments de combustibles nucléaires. Comme on l'a déjà indiqué, de tels déchets sont contaminés par du plutonium ou de l'uranium radioactif et peuvent contenir une certaine fraction d'eau ou de matières organiques solides ou liquides telles que des matières cellulosiques, des matières plastiques ou des hydrocarbures.By way of non-limiting example, the radioactive materials may be constituted by technological waste from a plant for the treatment or manufacture of nuclear fuel elements. As already mentioned, such wastes are contaminated with plutonium or radioactive uranium and may contain a certain fraction of water or solid or liquid organic materials such as cellulosic materials, plastics or hydrocarbons. .
Conformément à l'invention, on place à l'intérieur de l'enceinte fermée contenant les matières radioactives au moins deux produits actifs.According to the invention, at least two active products are placed inside the closed chamber containing the radioactive materials.
L'un de ces produits actifs, appelé par la suite "produit actif A", est conçu pour éliminer, par oxydation catalytique en continu par l'oxygène présent dans l'enceinte, les gaz inflammables, tels que l'hydrogène, produits par radiolyse dans l'atmosphère de l'enceinte, sous l'effet des radiations émises par les isotopes radioactifs présents dans lesdites matières.One of these active products, hereinafter referred to as "active product A", is designed to remove, by continuous catalytic oxidation by the oxygen present in the chamber, flammable gases, such as hydrogen, produced by radiolysis in the atmosphere of the enclosure, under the effect of radiation emitted by the radioactive isotopes present in said materials.
Le deuxième produit actif, appelé par la suite "produit actif B", est un produit actif conçu pour éliminer par oxydation en continu le monoxyde de carbone et former du CO2.The second active product, hereinafter referred to as "active product B", is an active product designed to continuously oxidise carbon monoxide and form CO 2 .
A ces deux produits actifs A et B peuvent éventuellement être associés un ou deux autres produits actifs.To these two active products A and B may optionally be associated with one or two other active products.
Ces deux autres produits actifs facultatifs comprennent un troisième produit, appelé par la suite "produit actif C", conçu pour constituer une source d'O2, permettant de pallier au manque d'oxygène une fois que tout l'oxygène initialement présent dans l'enceinte a été consommé ; et un quatrième produit, appelé par la suite "produit actif D", constitué par un produit actif absorbeur d'eau.These two other optional active products comprise a third product, hereinafter referred to as "active product C", designed to constitute a source of O 2 , making it possible to overcome the lack of oxygen once all the oxygen initially present in the pregnant was consumed; and a fourth product, hereinafter referred to as "active product D", consisting of an active water-absorbing product.
Le produit actif A comprend un support inerte solide, de préférence microporeux supportant un métal précieux (imprégné d'un métal précieux) tel que du palladium, du platine, du rhodium. En variante, le support inerte solide, de préférence microporeux, peut aussi supporter une terre rare (être imprégné d'une terre rare) choisie avantageusement dans le groupe des lanthanides, tels que le lanthane.Active product A comprises a solid, preferably microporous, inert support which supports a precious metal (impregnated with a precious metal) such as palladium, platinum or rhodium. Alternatively, the solid inert carrier, preferably microporous, may also support a rare earth (be impregnated with a rare earth) advantageously chosen from the group of lanthanides, such as lanthanum.
Le produit actif D est constitué par un support microporeux hygroscopique.The active product D is constituted by a microporous hygroscopic support.
Le support solide inerte du produit actif A, lorsque ce support est microporeux, et le support microporeux hygroscopique du produit actif éventuel D, sont généralement tous deux constitués par un tamis moléculaire qui possède une grande surface développée définie par une surface spécifique par exemple supérieure ou égale à 200, voire 300 m2/g.The inert solid support of the active product A, when this support is microporous, and the hygroscopic microporous support of the optional active product D, are generally both constituted by a molecular sieve which has a large developed surface defined by a specific surface, for example greater than equal to 200, even 300 m 2 / g.
Ainsi, lorsque le support microporeux du produit actif A est imprégné par un métal précieux ou une terre rare il présente une surface de réaction très importante pour l'oxydation des gaz inflammables produits par radiolyse dans l'atmosphère de l'enceinte et plus particulièrement l'hydrogène.Thus, when the microporous support of the active product A is impregnated with a precious metal or a rare earth, it has a very high reaction surface. important for the oxidation of flammable gases produced by radiolysis in the atmosphere of the enclosure and more particularly hydrogen.
Dans le produit actif A, le métal précieux ou la terre rare constitue un catalyseur de la réaction d'oxydation en continu de l'hydrogène, par l'oxygène contenu dans l'enceinte.In the active product A, the precious metal or the rare earth constitutes a catalyst for the continuous oxidation reaction of hydrogen by the oxygen contained in the chamber.
Généralement, la présence de moins de 0,1% en poids de métal précieux dans le support catalytique microporeux permet d'obtenir l'effet désiré.Generally, the presence of less than 0.1% by weight of precious metal in the microporous catalyst support provides the desired effect.
Le support inerte microporeux préféré du produit actif A et le support microporeux hygroscopique du produit actif D éventuel sont constitués généralement comme indiqué plus haut par un tamis moléculaire choisi de préférence pour ce qui concerne le support microporeux du produit actif D dans le groupe des silico-aluminates, de formule Na12 [(Aℓ02)12(SiO2)12] X H2, où X peut atteindre 27, ce qui représente 28,5% du produit anhydre, et pour ce qui concerne le support microporeux du produit actif A parmi les alumines de préférence activées.The preferred microporous inert support of the active product A and the microporous hygroscopic support of the active product D, if any, are generally constituted as indicated above by a molecular sieve preferably chosen with regard to the microporous support of the active product D in the group of silica-silicones. aluminates, of formula Na 12 [(AℓO 2 ) 12 (SiO 2 ) 12 ] XH 2 , where X can reach 27, which represents 28.5% of the anhydrous product, and as regards the microporous support of the active product A among the aluminas preferably activated.
Dans le produit actif A, la surface spécifique importante du support microporeux préféré permet d'utiliser au mieux l'action catalysante du métal précieux ou de la terre rare. En effet, on réalise une surface de réaction importante sur un matériau support, en utilisant peu de composé catalytique et dans des volumes réduits.In the active product A, the large specific surface area of the preferred microporous support makes it possible to use at best the catalytic action of the precious metal or the rare earth. Indeed, a large reaction surface is produced on a support material, using little catalytic compound and in reduced volumes.
Au contact du support inerte microporeux supportant le catalyseur (imprégné du catalyseur), l'hydrogène se combine avec l'oxygène de l'enceinte, pour former de l'eau. L'eau ainsi formée est piégée et fixée en profondeur dans les micropores du support préféré du produit A, par capillarité moléculaire. A titre d'exemple un tel support peut absorber jusqu'à 30% de sa masse d'eau.In contact with the microporous inert support supporting the catalyst (impregnated with the catalyst), the hydrogen combines with the oxygen of the enclosure, to form water. The water thus formed is trapped and fixed deep in the micropores of the preferred support of the product A, by molecular capillarity. By way of example, such a support can absorb up to 30% of its mass of water.
L'eau en excès, non absorbée par le support microporeux du produit actif A, est éventuellement piégée dans les micropores du support microporeux hygroscopique formant le produit actif D.The excess water, not absorbed by the microporous support of the active product A, is optionally trapped in the micropores of the microporous hygroscopic support forming the active product D.
De cette manière, on évite toute formation d'eau libre, qui risquerait d'être décomposée à nouveau par radiolyse, en restituant une partie de l'hydrogène éliminé. En effet, l'eau piégée en profondeur dans les supports microporeux est moins soumise aux effets des radiations émises dans l'atmosphère de l'enceinte que s'il s'agissait d'eau libre. Ou bien, si le produit actif D n'est pas présent, l'eau libre en excès non absorbée par le support du catalyseur a) peut alors réagir avec un produit actif C constitué par un peroxyde solide pour donner un dégagement d'oxygène.In this way, any formation of free water is avoided, which could be decomposed again by radiolysis, restoring some of the hydrogen removed. Indeed, the water trapped deep in microporous media is less subject to the effects of radiation emitted into the atmosphere of the chamber than if it were open water. Or, if the active product D is not present, the excess free water not absorbed by the catalyst support a) can then react with an active product C consisting of a solid peroxide to give a release of oxygen.
Par ailleurs, il est à noter que le procédé d'oxydation ainsi mis en oeuvre fonctionne parfaitement car l'atmosphère de l'enceinte ne peut atteindre un taux d'humidité important. Plus précisément, l'efficacité du produit actif D permet de garantir une humidité relative de l'ambiance de l'enceinte inférieure à environ 10%. Cela assure un rendement maximal aux réactions d'oxydation mettant en oeuvre les produits actifs A et B.Furthermore, it should be noted that the oxidation process thus implemented works perfectly because the atmosphere of the enclosure can not reach a high humidity level. More precisely, the effectiveness of the active product D makes it possible to guarantee a relative humidity of the enclosure environment of less than about 10%. This ensures a maximum yield of the oxidation reactions using the active products A and B.
Le produit actif B qui est obligatoirement placé à l'intérieur de l'enceinte, comprend un mélange d'oxydes de métaux, de préférence sous la forme de granulés qui permet d'éliminer en continu le CO par oxydation en CO2.The active product B which is necessarily placed inside the enclosure, comprises a mixture metal oxides, preferably in the form of granules which allows the CO to be continuously removed by oxidation to CO 2 .
Un produit préféré comprend un mélange de dioxyde de manganèse MnO2 et d'oxyde de cuivre CuO.A preferred product comprises a mixture of manganese dioxide MnO 2 and copper oxide CuO.
Le mélange de dioxyde de manganèse MnO2 et d'oxyde de cuivre CuO représente généralement environ 80% du poids du produit B (généralement environ 66% de MnO2 et 14% de CuO).The mixture of manganese dioxide MnO 2 and copper oxide CuO generally represents about 80% of the weight of product B (generally about 66% MnO 2 and 14% CuO).
Ce produit actif B joue un rôle particulièrement important, lorsque les gaz se trouvant dans l'enceinte contiennent du CO. En effet, et sans vouloir être lié par aucune théorie, il a alors été mis en évidence que les sites actifs du produit actif A sont bloqués par le CO car la molécule de CO est plus encombrante que la molécule d'H2. C'est donc le CO qui est alors converti préférentiellement par le catalyseur a) et non l'hydrogène. En d'autres termes, l'hydrogène n'est pas recombiné car le CO bloque les sites actifs du catalyseur a).This active product B plays a particularly important role, when the gases in the chamber contain CO. Indeed, and without wishing to be bound by any theory, it was then demonstrated that the active sites of the active product A are blocked by the CO because the CO molecule is more cumbersome than the H 2 molecule. It is therefore the CO that is then converted preferentially by the catalyst a) and not hydrogen. In other words, the hydrogen is not recombined because the CO blocks the active sites of the catalyst a).
Si l'on place en plus du catalyseur a), un catalyseur b) à l'intérieur de l'enceinte, celui-ci permet une oxydation du CO en CO2 beaucoup plus rapide que le catalyseur a). Les sites actifs du catalyseur a) sont alors plus disponibles pour assurer l'oxydation des gaz inflammables et notamment celle de l'hydrogène.If, in addition to the catalyst a), a catalyst b) is placed inside the enclosure, the CO 2 is oxidized much faster than the catalyst a). The active sites of the catalyst a) are then more available to ensure the oxidation of flammable gases and in particular that of hydrogen.
Un catalyseur qui peut être utilisé en tant que produit actif B est le produit vendu sous la dénomination de CARULITE® par la société ZANDER. Il s'agit d'un mélange comprenant du CuO et du MnO2 qui catalyse spécifiquement la réaction d'oxydation de CO en CO2.A catalyst which can be used as the active product B is the product sold under the name Carulite ® by ZANDER society. This is a mixture comprising CuO and MnO 2 which Specifically catalyzes the oxidation reaction of CO to CO 2 .
La CARULITE® catalyse par exemple cette réaction à une vitesse dix fois plus grande, que ne le fait le catalyseur a), et de ce fait le catalyseur a) reste disponible pour la réaction d'oxydation des gaz inflammables et en particulier pour la réaction d'oxydation de l'hydrogène en eau.The Carulite ® catalyzes this reaction, for example at a speed ten times greater, than does the catalyst), and therefore the catalyst a) still available for the oxidation reaction of combustible gases and in particular for the reaction oxidation of hydrogen into water.
Le rapport massique du produit actif B du produit actif A est généralement de 1/1 à 1/10, de préférence de 1/2 à 1/4. Ce rapport est généralement déterminé pour un rapport du débit de CO au débit de H2 généralement d'environ 1/11 ; ce rapport de débit est celui généralement produit par des déchets technologiques.The mass ratio of the active product B of the active product A is generally from 1/1 to 1/10, preferably from 1/2 to 1/4. This ratio is generally determined for a ratio of CO flow rate to H 2 flow rate generally about 1/11; this flow ratio is that usually produced by technological waste.
Le produit actif C qui est facultatif est défini comme étant une source d'oxygène. Cette source d'oxygène se trouve généralement soit sous forme gazeuse, soit sous forme solide.Active product C which is optional is defined as a source of oxygen. This source of oxygen is generally either in gaseous form or in solid form.
Dans ce dernier cas, il s'agit généralement d'un composé solide de la famille des peroxydes qui libère l'oxygène en présence d'eau. Cette eau est généralement l'eau formée au cours de l'oxydation de l'hydrogène par le catalyseur a) et qui n'a pas été absorbée par le support inerte solide de préférence microporeux du catalyseur a).In the latter case, it is usually a solid compound of the peroxide family that releases oxygen in the presence of water. This water is generally the water formed during the oxidation of hydrogen by the catalyst a) and which has not been absorbed by the solid inert carrier preferably microporous catalyst a).
De ce fait, lorsque le produit actif C est un tel peroxyde solide, il est préférable de ne pas utiliser de produit actif D afin que de l'eau reste disponible pour réagir avec le peroxyde et libérer l'oxygène.Therefore, when the active product C is such a solid peroxide, it is preferable not to use active product D so that water remains available to react with the peroxide and release the oxygen.
Le peroxyde solide est généralement choisi parmi les peroxydes de métaux alcalins et alcalino-terreux tels que les peroxydes de calcium, baryum, sodium, potassium, magnésium et leurs mélanges.The solid peroxide is generally selected from alkali and alkaline earth metal peroxides such as calcium peroxides, barium, sodium, potassium, magnesium and mixtures thereof.
La source d'oxygène sous forme solide est introduite initialement dans l'enceinte lorsqu'un déficit d'oxygène est prévu.The source of oxygen in solid form is initially introduced into the chamber when a deficit of oxygen is expected.
Afin de pouvoir être facilement utilisés et conditionnés dans l'enceinte, les produits actifs A, B, C, D se présentent généralement sous la forme, d'éléments discrets ou particules, telles que granulés, billes, cristaux. Ainsi, les supports microporeux des produits actifs A, et éventuellement D, sont avantageusement fractionnés en éléments, particules, de petites dimensions tels que des granules, des billes ou des cristaux.In order to be easily used and packaged in the chamber, the active products A, B, C, D are generally in the form of discrete elements or particles, such as granules, beads, crystals. Thus, the microporous supports of the active products A, and optionally D, are advantageously fractionated into small elements, particles, such as granules, beads or crystals.
De façon plus précise, chacun des éléments des supports microporeux a, de préférence, un diamètre enveloppe compris entre environ 2 mm et environ 20 mm. Chacun desdits éléments de supports microporeux supporte un (est imprégné d'un) métal précieux dans le cas du produit actif A. Le produit actif B se présente déjà généralement sous une forme fractionnée par exemple, à savoir généralement sous la forme de granules d'oxydes MnO2 et CuO.More specifically, each of the elements of the microporous supports preferably has a shell diameter of between about 2 mm and about 20 mm. Each of said microporous support elements supports a (is impregnated with) a precious metal in the case of the active product A. The active product B is already generally in a fractionated form for example, namely generally in the form of granules of oxides MnO 2 and CuO.
Lorsqu'il est présent le produit actif C, s'il s'agit d'un produit solide se présente généralement sous forme de poudre.When it is present the active product C, if it is a solid product is generally in the form of powder.
Le fractionnement des supports microporeux (produits actifs A et D) et le caractère déjà fractionné du produit actif B permet, de façon optionnelle et comme on le décrira plus précisément par la suite, de conditionner facilement au moins l'un des produits actifs dans divers types de récipients avant de les placer à l'intérieur de l'enceinte. Ce fractionnement permet aussi d'utiliser avec le maximum d'efficacité les propriétés du support microporeux, en augmentant encore les surfaces d'oxydation du support du produit actif A. En effet, lorsque l'hydrogène diffuse dans les éléments de petites dimensions formant les supports catalytiques microporeux, il vient s'oxyder autour des surfaces de tous ces éléments. Autrement dit, la surface totale d'oxydation correspond à la somme de toutes les surfaces des éléments formant le support, qui est beaucoup plus grande que la surface externe du volume global occupé par lesdits éléments.Fractionation of the microporous supports (active products A and D) and the character already The fraction of the active product B optionally allows, as will be described more precisely below, to easily package at least one of the active products in various types of containers before placing them inside the enclosure. This fractionation also makes it possible to use the properties of the microporous support with maximum efficiency, by further increasing the oxidation surfaces of the support of the active product A. In fact, when the hydrogen diffuses into the small elements forming the Microporous catalytic supports, it comes to oxidize around the surfaces of all these elements. In other words, the total oxidation surface corresponds to the sum of all the surfaces of the elements forming the support, which is much larger than the external surface of the overall volume occupied by said elements.
Le même raisonnement s'applique au fractionnement des supports du produit actif D, qui augmente les surfaces d'absorption d'eau.The same reasoning applies to the splitting of the supports of the active product D, which increases the water absorption surfaces.
Par conséquent, le fractionnement des supports du produit actif A et éventuellement D en petits éléments, le caractère fractionné des produits actifs B et C ainsi que l'utilisation de matériaux microporeux à grande surface spécifique, se combinent pour procurer au procédé selon l'invention une grande efficacité. L'hydrogène est oxydé efficacement sur de grandes surfaces, de même que le CO, et l'eau formée est piégée en profondeur dans les petits éléments, du fait des propriétés de capillarité des matériaux microporeux, en particulier du matériau du support du produit actif D.Therefore, the fractionation of the supports of the active product A and possibly D into small elements, the fractionality of the active products B and C and the use of microporous materials with a large specific surface area, combine to provide the process according to the invention. a great efficiency. Hydrogen is efficiently oxidized over large areas, as is CO, and the water formed is trapped deep within the small elements, due to the capillary properties of the microporous materials, particularly the carrier material of the active product. D.
Dans un mode de réalisation préféré de l'invention, le support microporeux des produits actifs A est de l'alumine activée Aℓ2O3, conditionnée en granules de petites dimensions. L'alumine activée Aℓ2O3 est un corps de grande surface spécifique, supérieure à 200 m2 par gramme, voire à 300 m2/g. Pour obtenir les meilleurs résultats, les granules d'alumine ont un diamètre enveloppe de quelques millimètres, compris de préférence entre environ 2 mm et environ 20 mm. Dans le cas du support du produit actif A, les granules sont faiblement imprégnées de métal précieux (moins de 0,1% en poids) ou de terre rare.In a preferred embodiment of the invention, the microporous support of the active products A is activated alumina Aℓ 2 O 3 , packaged in small granules. Activated alumina Aℓ 2 O 3 is a body with a large specific surface area greater than 200 m 2 per gram, or even 300 m 2 / g. For best results, the alumina granules have an envelope diameter of a few millimeters, preferably between about 2 mm and about 20 mm. In the case of the carrier of the active product A, the granules are poorly impregnated with precious metal (less than 0.1% by weight) or rare earth.
Dans ces conditions, une quantité de granules imprégnées du produit activé A correspondant à 1 litre en volume ou environ 800 g en poids, suffit pour éliminer plus de 400 litres d'hydrogène dans l'atmosphère libre d'une enceinte fermée.Under these conditions, a quantity of granules impregnated with the activated product A corresponding to 1 liter by volume or about 800 g by weight is sufficient to remove more than 400 liters of hydrogen in the free atmosphere of a closed chamber.
Dans une application particulière relative au transport de matières radioactives, celles-ci sont généralement conditionnées dans des récipients tels que des fûts arrimés à l'intérieur du conteneur. On dispose alors avantageusement les produits actifs à l'intérieur de ces récipients. Cela permet d'éliminer l'hydrogène directement où il est produit. Seule une très faible fraction de l'hydrogène s'échappera alors des récipients et diffusera dans le volume libre du conteneur, où il sera éliminé par les produits actifs, également disposés en faible quantité dans ce volume libre.In a particular application relating to the transport of radioactive materials, these are generally packaged in containers such as drums stowed inside the container. The active products are then advantageously placed inside these containers. This eliminates hydrogen directly where it is produced. Only a very small fraction of the hydrogen will then escape from the containers and will diffuse into the free volume of the container, where it will be removed by the active products, also arranged in small quantities in this free volume.
Si les récipients sont étanches, on peut choisir de disposer les produits actifs en quantité suffisante uniquement à l'intérieur de ces récipients. En effet, la concentration en hydrogène dans l'atmosphère du conteneur sera alors toujours insignifiante puisque l'hydrogène est éliminé dans les récipients et diffuse très peu dans l'enceinte du conteneur.If the containers are waterproof, we can choose to have the active products in quantity sufficient only inside these receptacles. Indeed, the concentration of hydrogen in the atmosphere of the container will then always be insignificant since the hydrogen is removed in the containers and diffuse very little in the enclosure of the container.
Il est à noter que l'introduction des produits actifs dans les récipients permet de continuer à prévenir l'accumulation d'hydrogène après leur déchargement final. De plus, si les récipients sont destinés à être stockés sur site pour une longue durée, les produits actifs peuvent éventuellement être renouvelés pour assurer l'élimination de hydrogène en continu sur le site de stockage. En d'autres termes, l'utilisation du procédé selon l'invention n'est pas limitée à l'élimination de gaz inflammables produits dans une enceinte fermée en cours de transport.It should be noted that the introduction of the active products in the containers makes it possible to continue to prevent the accumulation of hydrogen after their final unloading. In addition, if the containers are to be stored on site for a long time, the active products may possibly be renewed to ensure the elimination of hydrogen continuously on the storage site. In other words, the use of the method according to the invention is not limited to the elimination of flammable gases produced in a closed enclosure during transport.
En conclusion, le procédé selon l'invention est particulièrement simple à utiliser en association avec des enceintes de différentes natures contenant des matières radioactives comportant des composants organiques et éventuellement de l'eau. Les manipulations nécessaires à la mise en place des produits actifs à l'intérieur de l'enceinte sont particulièrement simples et rapides à effectuer. L'élimination des gaz inflammables produits par radiolyse à l'intérieur de l'enceinte est assurée efficacement. En outre, les durées de transport et de stockage peuvent être gérées de manière très souple puisqu'il suffit d'introduire à l'intérieur de l'enceinte lés quantités de produits actifs appropriées pour la durée de transport et/ou de stockage envisagée.In conclusion, the method according to the invention is particularly simple to use in combination with different types of enclosures containing radioactive materials comprising organic components and possibly water. The manipulations required to place active products inside the enclosure are particularly simple and quick to perform. The elimination of flammable gases produced by radiolysis inside the enclosure is effectively ensured. In addition, the transport and storage times can be managed in a very flexible way since it is sufficient to introduce inside the enclosure quantities of active products appropriate for the duration of transport and / or storage envisaged.
L'invention va maintenant être décrite en référence à l'exemple suivant, donné à titre illustratif et non limitatif.The invention will now be described with reference to the following example, given by way of illustration and not limitation.
Dans cet exemple, on illustre le procédé de l'invention en mettant en oeuvre les produits actifs a) et b) suivants :
- produit actif a) : alumine (support solide inerte microporeux) imprégnée de palladium (catalyseur) sous forme de billes de 3 mm et dont la surface spécifique est égale à 300 m2/gr ;
- produit actif b) : granules dont la composition chimique est la suivante : 65% de MnO2, 13% de CuO, 9% d'Al2O3 et environ 10% d'H2O. La dimension des granules est comprise entre 1 et 2 mm.
- active product a): alumina (microporous inert solid support) impregnated with palladium (catalyst) in the form of 3 mm beads and whose specific surface area is equal to 300 m 2 / gr;
- active product b): granules whose chemical composition is as follows: 65% of MnO 2 , 13% of CuO, 9% of Al 2 O 3 and approximately 10% of H 2 O. The size of the granules is between 1 and 2 mm.
L'essai a été réalisé sans produits actifs c) et d).The test was conducted without active products c) and d).
L'essai est réalisé de la manière suivante :The test is performed as follows:
On place dans une enceinte de 20 litres (sac Tedlar) contenant 600 ml d'hydrogène et 53 ml de monoxyde de carbone une quantité de produit actif a) décrit ci-dessus égale à 25 grammes et une quantité de produit actif b) décrit ci-dessus égale à 12,5 g (les produits sont conditionnés séparément). La concentration initiale en hydrogène est de l'ordre de 5,6%.A quantity of active product a) described above equal to 25 grams and an amount of active product b) described above is placed in a 20 liter chamber (Tedlar bag) containing 600 ml of hydrogen and 53 ml of carbon monoxide. above equal to 12.5 g (the products are packaged separately). The initial hydrogen concentration is of the order of 5.6%.
Un mélange H2/CO est injecté en continu avec les débits suivants : 5,6 ml/h pour le monoxyde de carbone et 65 ml/h pour l'hydrogène soit un rapport de débit H2/CO égal à 11,6.A mixture H 2 / CO is injected continuously with the following flow rates: 5.6 ml / h for the monoxide of carbon and 65 ml / h for hydrogen is a flow ratio H 2 / CO equal to 11.6.
Ce rapport est représentatif du rapport de débits d'H2 et de CO générés dans un emballage contenant des déchets compactés issus du retraitement de combustibles irradiés (dont la composition moyenne est de 90% de coques et embouts et 10% de déchets technologiques) ; les débits d'hydrogène et de monoxyde de carbone étant respectivement égaux à 2 litres/heure et 0,18 litres/heure.This report is representative of the ratio of H 2 and CO flows generated in a package containing compacted waste from the reprocessing of irradiated fuels (the average composition of which is 90% of hulls and end pieces and 10% of technological waste); the flow rates of hydrogen and carbon monoxide being respectively equal to 2 liters / hour and 0.18 liters / hour.
L'essai a duré 95 heures (jusqu'à épuisement de l'oxygène contenu dans l'enceinte). La teneur en hydrogène dans l'enceinte est mesurée tout au long de l'essai par chromatographie. Cette teneur reste inférieure à 1% (en volume) tout au long de l'essai comme le montre la courbe d'évolution de la teneur en H2 en fonction du temps (heures) donnée sur la
Claims (27)
- Method for removing inflammable gases produced by radiolysis in a closed chamber which is a receptacle, tank or container, suitable for transporting and/or storing radioactive matters, said closed chamber containing radioactive matters comprising organic compounds and possibly water, or radioactive matters in the presence of organic compounds and possibly water, in which the following are placed inside the chamber:a) a first catalyst of at least one reaction for oxidizing the inflammable gases by oxygen contained in the chamber atmosphere, supported by an inert solid support;b) a second catalyst of at least the reaction for oxidizing CO to CO2;and the inflammable gases react with oxygen contained in the chamber atmosphere, said oxidation reaction being catalyzed by the first catalyst.
- Method according to Claim 1, in which the catalyst a) is a catalyst of at least the reaction for oxidizing hydrogen to water.
- Method according to either of the preceding claims, in which the catalyst a) is a precious metal selected from the group consisting of platinum, palladium and rhodium.
- Method according to Claim 3, in which the inert solid support of the catalyst a) supports less than 0.1% by weight of precious metal.
- Method according to any one of Claims 1 to 3 in which the catalyst a) is a rare earth, selected from the lanthanide group.
- Method according to any one of the preceding claims, in which the inert solid support of the catalyst a) is a microporous inert solid support.
- Method according to Claim 6, in which the microporous inert solid support is selected from molecular sieves, possibly activated.
- Method according to Claim 7, in which the molecular sieve is made of a material selected from aluminas and activated aluminas.
- Method according to any one of Claims 6 to 8, in which the microporous inert solid support has a specific surface area of at least 200 m2/g, and preferably of at least 300 m2/g.
- Method according to any one of the preceding claims, in which the catalyst b) is a catalyst specific of the reaction for oxidizing CO to CO2.
- Method according to any one of the preceding claims, in which the catalyst b) comprises a mixture of manganese dioxide MnO2 and copper oxide CuO.
- Method according to any one of the preceding claims, in which the mass ratio of catalyst b) to catalyst a) is from 1/1 to 1/10, and preferably from 1/2 to 1/4.
- Method according to any one of the preceding claims, in which the following is also placed inside the chamber:c) an oxygen source.
- Method according to Claim 13, in which the oxygen source is in solid form or in gaseous form.
- Method according to Claim 14, in which the oxygen source c) is a solid source selected from solid peroxides.
- Method according to Claim 15, in which said solid peroxides are selected from peroxides of alkali and alkaline earth metals and mixtures thereof, such as peroxides of calcium, barium, sodium, potassium, magnesium, and mixtures thereof.
- Method according to Claim 14, in which the oxygen source is a gaseous source formed by replacing all or part of the chamber atmosphere by pure oxygen.
- Method according to any one of the preceding claims, in which a hygroscopic microporous support d) is also placed inside the chamber.
- Method according to Claim 18, in which the hygroscopic microporous support is selected from molecular sieves.
- Method according to Claim 19, in which the molecular sieve is made of a material selected from materials of the aluminosilicate type (for example with the formula Na12[(AℓO2)12(SiO2)12] X H2O, where X is up to 27, or 28.5% by weight of the anhydrous product.
- Method according to any one of Claims 18 to 20, in which the hygroscopic microporous support a) has a specific surface area of at least 200 m2/g, and preferably at least 300 m2/g.
- Method according to any one of Claims 6 to 21, in which the microporous inert solid support supporting the catalyst a), the catalyst b), and the optional hygroscopic microporous support d), are fractionated into discrete elements, such as crystals, beads or granules.
- Method according to Claim 22, in which said discrete elements have an envelope diameter of between about 2 mm and about 20 mm.
- Method according to either of Claims 22 and 23, in which at least one of the active products a), b) and possibly c) and d) is placed, mixed or separately, in at least one receptacle that is at least partially permeable, such as a textile envelope, a strainer, a metal grid or a perforated receptacle.
- Method according to Claim 24, in which the active products a) and b) are mixed, and the active products c) and d) are separate.
- Device for removing inflammable gases produced by radiolysis in a closed chamber which is a receptacle, tank or container, suitable for transporting and/or storing radioactive matters, said closed chamber containing radioactive matters comprising organic compounds and possibly water, or radioactive matters in the presence of organic compounds and possibly water, said device comprising:- a) a catalyst of at least one reaction for oxidizing the inflammable gases by oxygen contained in the chamber atmosphere, supported by an inert solid support,- b) a catalyst of at least the reaction for oxidizing CO to CO2,- c) possibly an oxygen source;- d) possibly a hygroscopic microporous inert solid support;in which the catalysts a) and b) are such as defined in any one of Claims 1 to 25, the oxygen source c) is such as defined in any one of Claims 13 to 25, and the hygroscopic microporous inert solid support d) is such as defined in any one of Claims 18 to 25.
- Closed chamber, which is a receptacle, tank or container, suitable for transporting and/or storing radioactive matters, said closed chamber being capable of containing radioactive matters comprising organic compounds and possibly water, or radioactive matters in the presence of organic compounds and possibly water, capable of producing inflammable gases, by radiolysis, said chamber further containing at least one device for removing inflammable gases as defined in Claim 26.
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FR0451817A FR2874120B1 (en) | 2004-08-09 | 2004-08-09 | METHOD AND DEVICE FOR REMOVING FLAMMABLE GASES IN A CLOSED ENCLOSURE AND ENCLOSURE EQUIPPED WITH SUCH A DEVICE |
PCT/FR2005/050647 WO2006021727A1 (en) | 2004-08-09 | 2005-08-04 | Method and device for removing flammable gases from a sealed chamber and chamber equipped with one such device |
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JP4691526B2 (en) * | 2007-05-31 | 2011-06-01 | 日立Geニュークリア・エナジー株式会社 | Radioactive waste disposal method |
FR2925752B1 (en) | 2007-12-21 | 2012-03-09 | Tn Int | DEVICE FOR TRANSPORTING AND / OR STORING RADIOACTIVE MATERIALS TO ENABLE CONTROLLED RELEASE OF OXYGEN IN A CLOSED ENCLOSURE |
FR2939700B1 (en) * | 2008-12-11 | 2014-09-12 | Commissariat Energie Atomique | MATERIAL FOR HYDROGEN TRAPPING, PROCESS FOR PREPARATION AND USES |
FR2971614A1 (en) | 2011-02-11 | 2012-08-17 | Tn Int | DEVICE FOR TRAPPING FLAMMABLE GASES PRODUCED BY RADIOLYSIS OR THERMOLYSIS IN A CONTAINMENT ENCLOSURE |
US9484122B2 (en) | 2011-12-30 | 2016-11-01 | Ge-Hitachi Nuclear Energy Americas Llc | Post-accident fission product removal system and method of removing post-accident fission product |
WO2016058525A1 (en) * | 2014-10-17 | 2016-04-21 | The Hong Kong University Of Science And Technology | Materials for moisture removal and water harvesting from air |
US10096392B2 (en) | 2015-08-13 | 2018-10-09 | P&T Global Solutions, Llc | Ion exchange column configured to reduce internal levels of radiolytic hydrogen gas |
CN106268307A (en) * | 2016-10-20 | 2017-01-04 | 中国船舶重工集团公司第七八研究所 | A kind of boxlike catalyst unit |
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US3179487A (en) * | 1958-12-02 | 1965-04-20 | Linde Eismasch Ag | Process for removing radioactive impurities from gases |
FR1476036A (en) * | 1965-04-02 | 1967-04-07 | Atomic Energy Authority Uk | Purification of the coolant of a nuclear reactor |
FR2061573B1 (en) * | 1969-07-25 | 1974-02-01 | Commissariat Energie Atomique | |
JPS6024497A (en) * | 1983-07-20 | 1985-02-07 | 株式会社日立製作所 | Method of filling catalyst |
JPS6140596A (en) * | 1984-07-10 | 1986-02-26 | 東洋エンジニアリング株式会社 | Batch type processing method of radioactive organic waste |
DE3730743A1 (en) * | 1987-09-12 | 1989-03-30 | Nuklear Service Gmbh Gns | Method for reducing the internal pressure build-up in a storage container for radioactive wastes |
DE3904149C2 (en) * | 1989-02-11 | 1994-01-20 | Kernforschungsz Karlsruhe | Device on containers with radioactive waste to reduce the internal pressure due to hydrogen formation |
JPH0752238B2 (en) * | 1989-04-28 | 1995-06-05 | 日揮株式会社 | Radiocarbon treatment method |
DE4126971A1 (en) * | 1991-08-14 | 1993-02-18 | Siemens Ag | METHOD AND DEVICE FOR DISPOSAL OF AN ORGANIC SUBSTANCE |
DE4343500A1 (en) * | 1993-12-20 | 1995-06-22 | Forschungszentrum Juelich Gmbh | Device for avoiding overpressures in storage containers with hydrogen-developing content |
DE19636557B4 (en) * | 1996-09-09 | 2005-02-03 | Framatome Anp Gmbh | Use of a catalyst system and recombination device for the recombination of hydrogen and oxygen, in particular for a nuclear power plant |
UA57884C2 (en) * | 1999-10-14 | 2003-07-15 | Дейвід БРЕДБЕРІ | Method for treatment of radioactive graphite |
JP2001228296A (en) * | 2000-02-17 | 2001-08-24 | Mitsubishi Heavy Ind Ltd | Canister and lid for it |
JP4615749B2 (en) * | 2001-03-22 | 2011-01-19 | 日揮株式会社 | Radioactive waste treatment method and apparatus |
DE10140858A1 (en) * | 2001-08-21 | 2003-03-06 | Solvay Interox Gmbh | Homogeneous boron-doped alkaline earth peroxide |
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US20080061007A1 (en) | 2008-03-13 |
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