Method of simulator preparation for spent nuclear fuel acid dissolving products clarification processes development

FIELD: fuel.

SUBSTANCE: invention relates to radiochemical technology and can be used for testing of equipment in spent nuclear fuel (SNF) processing technology. Method of simulator preparation for spent nuclear fuel acid dissolving products clarification processes development involves obtaining finely dispersed model suspension, containing solid-phase composition chemically inert in nitric acid media. Composition contains more than one component, representing fine dispersed hydrated oxide and metallide forms, which are introduced in form of separately prepared powders by dispersion in fluid to produce solid phase particles concentration of 10–35,000 mg/l, with solid phase particles density of 4.4–6.5 g/cm3, with solid phase particle size of 50–2,500 nm, with suspensions density of 1.3–2.4 g/cm3.

EFFECT: invention enables to simulate SNF acid dissolving product with account of its production method, type of SNF, burnup fraction, duration of conditioning before processing, operations preceding dissolution.

15 cl, 5 dwb, 1 tbl, 1 ex

 



 

Same patents:

Spent fuel storage // 2554112

FIELD: power industry.

SUBSTANCE: storage includes water basin 1 in the side walls of which there are return cooling tubes 2. At the bottom of basin 1 there laid are hollow disks 3 with perforation of microholes in the upper surface of disks and a conical mounting seat in the centre of disks 3, to which compressed air pipeline 4 is connected. Above hollow disks 3 there located are cylindrical holders 5 attached to each other and provided with holes 6 for water passage in the lower part of holders 5; fuel assemblies 7 are arranged in cylindrical holders 5. Water in basin 1 fully covers fuel assemblies 7 and upper holes of return cooling tubes 2. A loading mechanism performs positioning of a grab as per coordinates of centres of cylindrical holders 5 and performs loading of fuel assembly 7 to the chosen cylindrical holder 5. Walls of cylindrical holders 5 are attached to each other and form a spatial honeycomb structure.

EFFECT: improving use efficiency of basin volume due to increasing storage density of spent fuel; reducing the amount of water in the basin per unit weight of the stored spent fuel.

2 dwg

FIELD: chemistry.

SUBSTANCE: invention refers to agents for nitrate-comprising liquid radioactive waste (LRW) processing and can be used at nuclear power plants and specialised plants conditioning low and mean-active radioactive waste. In the declared method, before hardening in inorganic or polymer matrix material, the nitrate-containing LRW is biodegradable by the enzymatic processes with specially selected consortia of microorganisms with added phosphoric acid and saccharose; the microorganisms recover nitrate ions to molecular nitrogen, whereas a non-radioactive gas phase (nitrogen, carbon dioxide) is dumped. The radioactive nuclides are absorbed by biomass slag formed by the biodegradation and consisting of the microorganisms and their metabolites; phosphoric acid promotes carrying out the denitrification processes and additionally leads to strontium phosphate sedimentation that provides higher strength of the cement matrix.

EFFECT: reducing the amount of nitrate-containing LRW before added to the inorganic (cement, ceramic) or polymer matrix, reducing the amount of long-storage (burial) final product, preventing biodegradation of nitrate-containing LRW as a part of long-storage cement compound.

3 cl, 1 tbl, 2 dwg

FIELD: chemistry.

SUBSTANCE: method involves the sequential processing of a capsule with an acid solution and washing the capsule with an aqueous solution, which are heated to bubble heating. The capsule placed into the first container is washed for 10-20 minutes in boiling distilled water; the washed capsule placed into the second container is deactivated for 10-20 minutes by boiling 7-10% nitric acid; the second container is cooled down together with the capsule for 10-20 minutes. After cooling down, the nitric acid 50 ml is sampled from the second container to measure its radioactivity. If the sample radioactivity is less than 0.2 kBq, the capsule is considered to be clean, otherwise the washing and deactivation procedures are repeated with using boiling pure distilled water and 7-10% nitric acid to produce samples having a radioactivity of less than 0.2 kBq.

EFFECT: simplifying the technology and reducing the cost price of deactivating the capsule with ionising radiation source.

2 cl

FIELD: chemistry.

SUBSTANCE: invention relates to method of recycling radioactive wastes, in particular porous-fibrous heat-insulating materials (HIM), formed in the process of exploitation of objects of nuclear power and industry. Claimed method includes cold pressing of wastes into briquettes, followed by the process of high-temperature processing in electric furnace of chamber type to heat pressed wastes to temperature 1050-1150°C with the further exposure for not less than 1 hour at the same temperature. After that formed glass-like material is cooled at the environment temperature.

EFFECT: reduction of carryover of cezium-137 in gaseous phase from 9-20% to 1-2%; simplification of technology of HIM recycling due to elimination of technological operations of drying, crushing, addition of reagents and thorough mixture mixing before thermal processing, possibility to apply simple, available, less metal-consuming and costing technological equipment, which does not require highly qualified personnel for servicing, at least 4-fold reduction of energy consumption for HIM processing; elimination of formation of additional secondary solid radioactive wastes.

1 tbl

FIELD: physics, atomic power.

SUBSTANCE: invention relates to means of burying and recycling liquid radioactive wastes and can be used at facilities storing radioactive wastes of low and medium activity in storages of different types, as well as in radioactive contamination areas with potential escape of components of radioactive wastes into the environment. The disclosed method includes selecting effectively high radio-resistant strains of microorganisms, capable of oxidising organic components of radioactive wastes (acetate, oxalate etc.) and reducing nitrate anions and transvalent radionuclides, thereby limiting distribution thereof into the geologic environment, and also selecting concentrations of aqueous solutions of carbohydrates to stimulate microbiological processes in underground conditions.

EFFECT: reduced distribution of components of radioactive wastes from burial and radioactive contamination areas.

3 cl, 2 dwg

FIELD: physics, atomic power.

SUBSTANCE: invention relates to methods of treating irradiated reactor graphite. The disclosed method includes thermal decomposition and oxidation steps. The method includes a preparatory step of placing graphite in a thermal chamber, blowing a gaseous inert medium through the thermal chamber, said medium heated to maximum temperature of 700-1100°C, to release gaseous radioactive decomposition products into the inert medium. Further, the gaseous inert medium is treated for extraction and subsequent recycling of radioactive compounds of tritium and chlorine-36. Further, the method includes an oxidation step, where a gaseous oxygen-containing medium is blown through the thermal chamber to release gaseous radioactive oxidation products into the oxygen-containing medium, wherein the temperature of the medium is kept higher than 500°C, but lower than the maximum temperature of the gaseous inert medium at the thermal decomposition step. The obtained oxygen-containing medium with radioactive reaction products is then removed from the thermal chamber and treated for extraction and subsequent recycling of radioactive compounds of carbon-14. At the final step graphite is retrieved from the thermal chamber.

EFFECT: high efficiency of purifying irradiated reactor graphite from radionuclides owing to deep volumetric and selective deactivation thereof, and safer deactivation.

4 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: in the method, a nitrate solution of a meta, which is a component of radioactive wastes, is mixed in ethanol with tetraethoxysilane diluted with ethanol, followed by addition of an organic acid, preferably ascorbic acid. The mixture is then stirred at room temperature for 2-5 hours, preferably 4 hours, during the initial phase of hydrolysis occurs. The obtained silicate-hydroxy-nitrate-ascorbic sol containing the metal element which is a component of radioactive wastes then undergoes a second hydrolysis phase and polymerisation at 70°C. The sol is then evaporated to a dry residue at 0.1 MPa. Heat treatment of the obtained gel is carried out for 4 hours at 1200°C with a heating rate of 2°C/min.

EFFECT: obtaining silicate glass with a metal element firmly embedded in its structure, shorter and simpler process cycle.

10 cl, 4 ex

FIELD: machine building.

SUBSTANCE: spraying of waste by an air-stream atomiser and its burning in a cyclone furnace are provided. The cyclone furnace is heated by the heat from the combustion of gaseous or liquid fuel, liquid organic radioactive waste is supplied for combustion continuously, prior to the supply to the air-stream atomiser for spraying, the waste is heated, the air-stream atomiser is cooled by water, the waste is burnt in the presence of fine catalyst particles, secondary air is fed tangentially, cooling and purification of gases are carried out in a bubble column of a jet scrubber first and then in an absorber-condenser. Fuel combustion to heat the cyclone furnace is performed in fluidised bed of catalyst, liquid organic radioactive waste is heated by cooling water of the air-stream atomiser. The plant for liquid organic radioactive waste combustion comprises a cyclone furnace (1) with an air-stream atomiser, a jet scrubber (2), an absorber-condenser (3), water pumps (4/2 and 4/3), a catalytic reactor (7) with fluidised bed of catalyst is used as a starter. The cyclone furnace is mounted on the tank of the jet scrubber, the air-stream atomiser for the supply of liquid organic radioactive waste is located in the upper part of the cyclone furnace.

EFFECT: increased efficiency and environmental safety of liquid organic radioactive waste combustion.

6 cl, 1 dwg, 1 tbl

FIELD: physics, atomic power.

SUBSTANCE: invention relates to methods of processing uranium-containing solutions obtained from dissolving fluorination cinder when producing uranium hexafluoride. The method includes dissolving cinder in nitric acid solution, extracting uranium from the fluorine-containing nitric acid solution via reduction thereof with hydrazine on a platinum catalyst, with constant removal of uranium tetrafluoride precipitate from the catalyst surface, separating the catalyst from the nitric acid solution and the uranium tetrafluoride precipitate, providing an equimolar radio of fluoride ions to uranium (IV) in the obtained solution and separating the uranium tetrafluoride precipitate from the nitric acid solution, wherein the nitric acid solution is reused to resolve fluorination cinder with preliminary fortification with nitric acid.

EFFECT: invention provides a high degree of reducing uranium and reduces the amount of nitrate- and fluorine-containing wastes.

3 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: method includes neutralising complexing ligands contained in nitrate solution of carbide fuel via oxidation thereof with nitric acid in the presence of a catalyst in the form of a polyvalent metal which is located in the nitrate solution or is added before or after dissolving spent carbide nuclear fuel, said metal being selected from: cerium, iron, manganese, technetium, mercury. Further, the method includes heating the nitrate solution of the carbide fuel or performing oxidation directly in the process of dissolving the carbide fuel in nitric acid in the presence of a catalyst with subsequent dissolution in the oxidised solution of the carbide fuel of the oxide or metallic spent nuclear fuel, or performing simultaneous oxidation of complexing ligands and dissolving the oxide or metallic spent nuclear fuel in the solution of the carbide fuel. An alternative solution includes performing similar preparation of the spent carbide nuclear fuel for extraction processing, followed by mixing the oxidised solution of the carbide fuel with solutions of oxide or metallic spent nuclear fuel or direct addition of the required amount of a zirconium nitrate solution or a solution of another polyvalent metal-complexing agent.

EFFECT: avoiding the need to use powerful oxidising agent.

13 cl, 12 ex

FIELD: nuclear engineering.

SUBSTANCE: the proposed method of removal of irradiated material from nuclear reactor plate includes the irradiated material shielding with a shield material and their following removal of both materials. The shielding is fulfilled with a granulated material. Removal of irradiated and granulated materials is carried out by means of an auxiliary tube with a grate, confining the irradiated material and permeable for granulated material. The auxiliary tube is installed into the tube of a reactor fuel channel.

EFFECT: decreasing the idle time of reactor or/and production equipment.

1 cl, 1 dwg

FIELD: soil decontamination from radionuclides by technological methods.

SUBSTANCE: proposed method includes soil plowing and introduction of chemical agents into it. Ground limestone or dolomite in the amount of 5 or 6 tons per ha and potassium fertilizers KCl, KNO3, or KMgCl, *6H2O in the amount of 200 kg per ha are introduced in plowed layer followed by sowing perennial grass which is mowed in autumn and placed in storage excluding migration of radionuclides.

EFFECT: facilitated procedure, enhanced degree of soil decontamination from radionuclides.

3 cl, 1 dwg, 1 ex

FIELD: agriculture, in particular, environment protection, more particular, reduction of 137Cs level in soil.

SUBSTANCE: method involves growing accumulating plants such as lentils and Jerusalem artichoke on contaminated soil during three vegetation periods; alienating the entire plant biomass from soil at the end of vegetation period; determining soil cleaning extent from formula: Cη=(Ca-Cs/Ca)*100(%), where Cη is extent of cleaning soil; Ca is level of 137Cs in soil before planting of said accumulating plants; Cs is level of 137Cs in soil after withdrawal of the entire plant biomass from soil at the end of vegetation period.

EFFECT: reduced specific activity of 137Cs in soil, increased efficiency in removal of radio nuclides and obtaining of ecologically clean plant products, reduced possibility of external and internal radiation of people.

2 tbl

FIELD: chemical industry; building industry; methods and the cleaning gels for the surfaces treatment.

SUBSTANCE: the invention is pertaining to the method of the surface treatment with the cleaning gel and may be used for the surface degreasing and decontamination, and also for removal of the oxide layers from the surface. The method provides for: deposition of the cleaning gel onto the treated surface; aging of the cleaning gel on the treated surface at such a temperature and relative humidity, at which the gel dries and at that there is enough time for the gel to treat the surface before the dry and solid residue forms; removal of the dry and solid residue from the treated surface by suction or by the brush. The gel includes the mixture of the pyrogenetic silica and the sedimentary silica, the cleaning agent and possibly the oxidative agent. The invention ensures regulation of the dimensions of the dry residues of the gel and the time of drying sufficient for the effective treatment of any type surface, and also allows to reduce the quantity of the drainages formed during such treatment of the surfaces.

EFFECT: the invention ensures control over the dimensions of the dry residues of the gel and the time of drying sufficient for the effective treatment of any type surface, and also allows to reduce the quantity of the drainages formed during such treatment of the surfaces.

22 cl, 8 dwg, 5 ex

FIELD: nuclear engineering; preservation of dry, wet, and liquid radioactive wastes.

SUBSTANCE: proposed composition has resin portion of cold-cured compound ATOMIK and filler. Resin portion ingredients are as follows, parts by weight: epoxy oligomer, 100;, curing agent (aromatic amines), 38-50 furfural, 9-11. Used as filler is composition incorporating following ingredients, parts by weight: cement, 50-100; marshalite, 50-100 or bentonite, 50-100, or when they are jointly used: marshalite, 90-100 and bentonite, 90-100. Such composition provides for desired radiation resistance in absence of leaching of alpha-, beta-, and gamma-active radionuclides from preserved specimens of reactor graphite.

EFFECT: enhanced radiation stability of preserved specimens free from pits and voids, and adequate lifetime of preserved wastes; ability of their depreservation.

1 cl, 2 dwg, 2 tbl, 2 ex

FIELD: modeling plutonium dispersion processes in emergency explosion situations at its using entity.

SUBSTANCE: proposed method that can be used to simulate plutonium properties in case of emergency explosion involving escape of plutonium aerosols into atmosphere and to predict degree of radioactive pollution of terrain in emergency situations includes use of metal cerium as plutonium simulator in modeling processes of plutonium dispersion and escape of its aerosols into atmosphere in case of emergency explosion at using entity.

EFFECT: enhanced environmental friendliness of method.

1 cl

FIELD: immobilization of radioactive wastes.

SUBSTANCE: proposed silicate matrix for conditioning radioactive wastes has SiO2, Na2O, K2O, CaO, Fe2O3, Cr2O3, NiO, Al2O3, ZrO2, oxides of radioactive waste components including nuclear fuel fission products, U, transuranium elements. Proportion of mentioned components used in matrix is as follows, mole percent: SiO2, 60-68; sum of Na2O, K2O, Cs2O, 11-18; sum of CaO, SrO, BaO, 3-6; sum of Fe2O3, Cr2O3, NiO, 2-4; Al2O3, 1-3; ZrO2, 4-7; sum of rare-earth elements, U, and transuranium elements, 1.5; the rest, 3.

EFFECT: enhanced chemical and thermal stability of matrix.

1 cl, 3 dwg, 3 tbl, 8 ex

FIELD: nuclear power engineering; removing radioactive pollutants from surfaces of pieces of equipment or parts by means of circulating solutions.

SUBSTANCE: proposed process for controlling cyclic decontamination involving saturation of decontaminating solution with radionuclides includes chemical treatment of surface pollutants with decontaminating solution, checkup of solution saturation with radionuclides, termination of chemical treatment as soon as saturation of decontaminating solution with radionuclides is brought to limiting value, and removal of saturated decontaminating solution. Ionizing radiation dose rate is remotely measured by means of gamma transducers installed at reference points and chemical treatment is ceased as soon as inequality conditions are satisfied.

EFFECT: enhanced reliability of process due to optimal evaluation of chemical treatment time; enhanced efficiency and quality of decontamination due to reduced secondary sorption of radionuclides.

3 cl, 18 dwg

FIELD: nuclear power engineering.

SUBSTANCE: proposed method designed for controlling cyclic decontamination process by determining optimal time of completing separate decontamination steps involving uninterrupted cleaning of decontaminating solutions in filters and primarily intended for removing radioactive pollutants from surfaces of equipment or separate parts by circulating solution, for instance for decontaminating inner surfaces of nuclear power reactor equipment such as coolant circuits of boiling water reactors (heavy-power pressure-tube reactors RBMK) includes chemical loosening operations and dynamic loosening conducted before and after chemical loosening operation, as well as washing to discharge radioactive pollutants from coolant circuit to filters during each loosening operation. Radioactivity level of pollutants discharged from coolant circuit is periodically checked against reference radionuclides, and each decontaminating operation is completed upon attaining following condition: . In addition, radioactivity level of pollutants discharged from coolant circuit is proposed to be calculated by sum of derived radioactivity of 3-7 reference radionuclides; 58,60Co, 54Mn, 59Fe 95Zr, and 95Nb are used as reference radionuclides.

EFFECT: enhanced reliability of process control due to determining optimal time of completing separate steps, reduced decontamination time, enhanced effectiveness due to reduced secondary sorption of radionuclides.

3 cl, 13 dwg, 3 tbl

FIELD: recovering and degreasing liquid radioactive wastes.

SUBSTANCE: proposed method for decontaminating waste water from radioactive components incorporating in their composition dissolved and/or emulsified mineral oil, dissolved and solid particles of uranium radioactive components, and products of its decay by concentration of radioactive components and mineral oil. Prior to recovery waste water is acidified to pH = 2.5-3.0. Then iron salt based coagulant (III) and modified polyacrylamide based flocculant are introduced. After that waste water is neutralized with alkali to pH > 7 followed by centrifuging purified water and concentrate containing radioactive components and mineral oil. For final procedure concentrate is solidified and buried.

EFFECT: reduced energy requirement, enhanced speed of process.

1 cl, 5 tbl, 5 ex

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