CA2265413A1 - A method for complex decontamination of metal surfaces with deep and surface contamination and of liquid radioactive wastes - Google Patents
A method for complex decontamination of metal surfaces with deep and surface contamination and of liquid radioactive wastes Download PDFInfo
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- CA2265413A1 CA2265413A1 CA002265413A CA2265413A CA2265413A1 CA 2265413 A1 CA2265413 A1 CA 2265413A1 CA 002265413 A CA002265413 A CA 002265413A CA 2265413 A CA2265413 A CA 2265413A CA 2265413 A1 CA2265413 A1 CA 2265413A1
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- decontamination
- radionuclides
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 15
- 239000002184 metal Substances 0.000 title claims abstract description 15
- 239000010857 liquid radioactive waste Substances 0.000 title claims abstract description 12
- 238000005202 decontamination Methods 0.000 title claims description 31
- 230000003588 decontaminative effect Effects 0.000 title claims description 30
- 238000000034 method Methods 0.000 title claims description 27
- 238000011109 contamination Methods 0.000 title claims description 11
- 239000000243 solution Substances 0.000 claims abstract description 17
- 239000000126 substance Substances 0.000 claims abstract description 15
- 239000003864 humus Substances 0.000 claims abstract description 12
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 7
- 230000006378 damage Effects 0.000 claims abstract description 5
- 230000000694 effects Effects 0.000 claims description 8
- 230000002285 radioactive effect Effects 0.000 claims description 7
- 239000003792 electrolyte Substances 0.000 claims description 5
- 239000008151 electrolyte solution Substances 0.000 claims description 3
- 159000000014 iron salts Chemical class 0.000 claims description 3
- -1 metals salts Chemical class 0.000 claims description 3
- 239000000276 potassium ferrocyanide Substances 0.000 claims description 3
- 239000000725 suspension Substances 0.000 claims description 3
- XOGGUFAVLNCTRS-UHFFFAOYSA-N tetrapotassium;iron(2+);hexacyanide Chemical compound [K+].[K+].[K+].[K+].[Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] XOGGUFAVLNCTRS-UHFFFAOYSA-N 0.000 claims description 3
- 150000002739 metals Chemical class 0.000 claims description 2
- 239000000941 radioactive substance Substances 0.000 claims description 2
- 239000007787 solid Substances 0.000 claims description 2
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims 1
- 238000004380 ashing Methods 0.000 claims 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims 1
- 239000003795 chemical substances by application Substances 0.000 claims 1
- 150000003841 chloride salts Chemical class 0.000 claims 1
- 150000004679 hydroxides Chemical class 0.000 claims 1
- 235000012249 potassium ferrocyanide Nutrition 0.000 claims 1
- 229910021653 sulphate ion Inorganic materials 0.000 claims 1
- 238000009792 diffusion process Methods 0.000 abstract description 3
- 239000007864 aqueous solution Substances 0.000 abstract description 2
- 230000003993 interaction Effects 0.000 abstract 1
- 239000011159 matrix material Substances 0.000 abstract 1
- 229910052792 caesium Inorganic materials 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 2
- 235000012206 bottled water Nutrition 0.000 description 2
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000003651 drinking water Substances 0.000 description 2
- 239000004021 humic acid Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000010808 liquid waste Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- QJZYHAIUNVAGQP-UHFFFAOYSA-N 3-nitrobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid Chemical compound C1C2C=CC1C(C(=O)O)C2(C(O)=O)[N+]([O-])=O QJZYHAIUNVAGQP-UHFFFAOYSA-N 0.000 description 1
- 229910052684 Cerium Inorganic materials 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 239000005569 Iron sulphate Substances 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000005065 mining Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 239000002900 solid radioactive waste Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof
- G21F9/002—Decontamination of the surface of objects with chemical or electrochemical processes
- G21F9/004—Decontamination of the surface of objects with chemical or electrochemical processes of metallic surfaces
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
- G21F9/06—Processing
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/28—Treating solids
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Chemical & Material Sciences (AREA)
- Electrochemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Food Science & Technology (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
Essence of the invention consists in electrochemical destruction of oxide films, situated on metal surface and impeding the diffusion of radionuclides deeply contaminating metal, and in intensification of their transfer from depth to surface at the expense of potential, applied to the metal surface, with subsequent interaction of radionuclides with humus substances which make up main component of decontaminating solution. In aqueous solutions humus substances dissociate with formation of negatively charged matrix interacting with radionuclides on the surface being decontaminated, followed by formation of insoluble substances, thus removing radionuclides from the formed liquid radioactive wastes.
Description
METHOD FOR COMPLEX DECONTAMINATION OF METAL SURFACES
WITH DEEP AND SURFACE CONTAMINATION AND OF LIQUID
RADIOACTIVE WASTES
The invention refers to electrochemical decontamination of contaminated metal surfaces, for example, components of nuclear power plants, and is based on contacting the surface being decontaminated with a special electrolytic solution. Decontamination is carried out with the help of a system of electrodes, which is followed by treatment of the used solution.
In the process of operation of nuclear power plants, as well as plants for mining and processing of rare earth elements, deep and surface contamination of equipment, contacting radioactive substances, takes place. In the case of complicated deep contamination chemical methods for decontamination by means of aggressive media such as those disclosed in Russian Patent No. 1,830,149, c1.G21 F9/00, 1993 or Russian Patent No. 2,017,244, cl.
G21 F9/36, 1994 are very expensive and ecologically hazardous for personnel. Electropolishing method such as those disclosed in Russian Patent No. 2,009,557, c1.G21 F9/34, 1994 or German Patent No.
3,343,396, c1.G21 F9/30, 1985 used for such purposes, consist in removal of a rather thick layer from the metal surface, thickness of which depends on the depth of radionuclides diffusion layer.
This results in considerable consumption of power and change of dimensions of objects being decontaminated.
The objective ofthe invention is to provide a method and compound for decontamination of radioactive contaminated metal objects by means of electrochemical destruction of oxide films impeding diffusion of radionuclides to metal surface. After the destruction of oxide films the positive potential, applied to the object being decontaminated, promotes movement of radionuclides to the surface. Deep contamination presents in fact a more complex case of surface decontamination. In fact, destruction and removal of oxide films transforms deep contamination into surface contamination. (see. A. D. Zimon, U.K. Pikalov, Decontamination, Izdat (Publishing House), Moscow, 1994 p. 40,96.) Humus substances have been found to be effective means for decontamination of metals with contaminated surfaces and they are added to the electrolytic compound for intensification of the decontamination process.
Anions of humus substances, added to electrolyte composition, interact with canons of radionuclides situated on the surface being decontamination. Electrochemical processes lead al so to changes in chemical structure of humus substances and result in formation of fractions with still higher decontaminating effect.
In the method of the present invention, a solution of liquid radioactive wastes is obtained electrolytically in decontamination of metal objects. A resulting insoluble residue consists of humic acids and positive radionuclides (for example, such as Cs, Sr, Co, Mn, Fe, Ni, Ce). Thus, in this case, humic acid plays the role of a flocculent. For intensification of decomposition and reduction of content of radionuclides down to a required level, the introduction of a humus substances suspension may be repeated with the use of special additives. For example, for removal of radioactive cesium it is necessary to add to the solution a microquantity of potassium ferrocyanide which, being adsorbed on colloidal particles of humus substances, additionally bonds cesium ions by transforming them into an insoluble state. In case the proposed method, it is not necessary to prepare adsorbents in advance, as their formation and the absorption of radionuclides in the solution proceed simultaneously. Iron salts may be used as flocculants for treatment of liquid wastes for final removal of multivalent radionuclides from liquid wastes. In case of decontamination of iron containing objects (steel, pig iron) by the proposed method the solution is saturated by iron ions in the process of decontamination at the expense of dissolution of oxide films and partially surface itself, which considerably decreases the amount of reagent used.
The residue of organic substances containing radionuclides formed according to the present invention is preferably ashed with the aim of reducing the amount of solid radioactive wastes isolated from the solution. Decontaminated aqueous solution may be used repeatedly.
The invention is explained by the following examples:
Example 1 Part of deeply contaminated 10 X 10 cm steel plate, which had been in a durable contact with uranium concentrate and was unamenable to decontamination by submersion into regular decontaminating solutions based on surfactant and organic acids, was subject to decontamination by the proposed method. The object being tested served as anode while a titanium plate was used as cathode, and alkaline suspension of humus substances with sodium sulfate additives was used as an electrolyte. After two hours off decontamination ~3-activity reduced 10 times, and y-activity reduced from 1000 ,uR/h to the background after three hours.
WITH DEEP AND SURFACE CONTAMINATION AND OF LIQUID
RADIOACTIVE WASTES
The invention refers to electrochemical decontamination of contaminated metal surfaces, for example, components of nuclear power plants, and is based on contacting the surface being decontaminated with a special electrolytic solution. Decontamination is carried out with the help of a system of electrodes, which is followed by treatment of the used solution.
In the process of operation of nuclear power plants, as well as plants for mining and processing of rare earth elements, deep and surface contamination of equipment, contacting radioactive substances, takes place. In the case of complicated deep contamination chemical methods for decontamination by means of aggressive media such as those disclosed in Russian Patent No. 1,830,149, c1.G21 F9/00, 1993 or Russian Patent No. 2,017,244, cl.
G21 F9/36, 1994 are very expensive and ecologically hazardous for personnel. Electropolishing method such as those disclosed in Russian Patent No. 2,009,557, c1.G21 F9/34, 1994 or German Patent No.
3,343,396, c1.G21 F9/30, 1985 used for such purposes, consist in removal of a rather thick layer from the metal surface, thickness of which depends on the depth of radionuclides diffusion layer.
This results in considerable consumption of power and change of dimensions of objects being decontaminated.
The objective ofthe invention is to provide a method and compound for decontamination of radioactive contaminated metal objects by means of electrochemical destruction of oxide films impeding diffusion of radionuclides to metal surface. After the destruction of oxide films the positive potential, applied to the object being decontaminated, promotes movement of radionuclides to the surface. Deep contamination presents in fact a more complex case of surface decontamination. In fact, destruction and removal of oxide films transforms deep contamination into surface contamination. (see. A. D. Zimon, U.K. Pikalov, Decontamination, Izdat (Publishing House), Moscow, 1994 p. 40,96.) Humus substances have been found to be effective means for decontamination of metals with contaminated surfaces and they are added to the electrolytic compound for intensification of the decontamination process.
Anions of humus substances, added to electrolyte composition, interact with canons of radionuclides situated on the surface being decontamination. Electrochemical processes lead al so to changes in chemical structure of humus substances and result in formation of fractions with still higher decontaminating effect.
In the method of the present invention, a solution of liquid radioactive wastes is obtained electrolytically in decontamination of metal objects. A resulting insoluble residue consists of humic acids and positive radionuclides (for example, such as Cs, Sr, Co, Mn, Fe, Ni, Ce). Thus, in this case, humic acid plays the role of a flocculent. For intensification of decomposition and reduction of content of radionuclides down to a required level, the introduction of a humus substances suspension may be repeated with the use of special additives. For example, for removal of radioactive cesium it is necessary to add to the solution a microquantity of potassium ferrocyanide which, being adsorbed on colloidal particles of humus substances, additionally bonds cesium ions by transforming them into an insoluble state. In case the proposed method, it is not necessary to prepare adsorbents in advance, as their formation and the absorption of radionuclides in the solution proceed simultaneously. Iron salts may be used as flocculants for treatment of liquid wastes for final removal of multivalent radionuclides from liquid wastes. In case of decontamination of iron containing objects (steel, pig iron) by the proposed method the solution is saturated by iron ions in the process of decontamination at the expense of dissolution of oxide films and partially surface itself, which considerably decreases the amount of reagent used.
The residue of organic substances containing radionuclides formed according to the present invention is preferably ashed with the aim of reducing the amount of solid radioactive wastes isolated from the solution. Decontaminated aqueous solution may be used repeatedly.
The invention is explained by the following examples:
Example 1 Part of deeply contaminated 10 X 10 cm steel plate, which had been in a durable contact with uranium concentrate and was unamenable to decontamination by submersion into regular decontaminating solutions based on surfactant and organic acids, was subject to decontamination by the proposed method. The object being tested served as anode while a titanium plate was used as cathode, and alkaline suspension of humus substances with sodium sulfate additives was used as an electrolyte. After two hours off decontamination ~3-activity reduced 10 times, and y-activity reduced from 1000 ,uR/h to the background after three hours.
Example 2 Samples of steam generator pipe and of pipeline of autonomous pump circuit made of 1 X 18H9T and 08X 18H 1 OT (Russian standard) steel, correspondingly, were decontamination by the proposed method. During 20 years of operation they were in contact with a heat carrier of the primary circuit which had the following parameters: temperature :260°C, specific activity:
106 Bq/1 and pH approximately 6.5, which promoted the formation of a solid oxide film with radionuclides sorbed in it.
Decontamination results are given in Table 1.
'table 1 Results of gamma-spectrometric measurement Name of Sample Initial Specific Specific ActivityDecontamination Gravity after activity for Co-60,decontamination, Factor Bq/cmz Bq/cmz Steam Generator 8.1 E + S 1. I E + 2 733 Pipe Pipe of autonomous4.4E + 5 1.6E + 2 272 circuit Ferrous metal pipes with the level of contamination about 400 ~cR/h were decontaminated by the method described in Example 1. y-activity reduced to background after 10 minutes of decontamination.
106 Bq/1 and pH approximately 6.5, which promoted the formation of a solid oxide film with radionuclides sorbed in it.
Decontamination results are given in Table 1.
'table 1 Results of gamma-spectrometric measurement Name of Sample Initial Specific Specific ActivityDecontamination Gravity after activity for Co-60,decontamination, Factor Bq/cmz Bq/cmz Steam Generator 8.1 E + S 1. I E + 2 733 Pipe Pipe of autonomous4.4E + 5 1.6E + 2 272 circuit Ferrous metal pipes with the level of contamination about 400 ~cR/h were decontaminated by the method described in Example 1. y-activity reduced to background after 10 minutes of decontamination.
Part of a lead screen with the level of contamination about 150 ,uR/h, which had been used for biological protection at nuclear power plant, was decontaminated by the above-described method. Radioactivity was reduced down to the background after 5 minutes.
A working piece of the primary circuit of nuclear reactor (a return valve), which had (3-radiation activity of 3000 particles/cmz min, was subject to decontamination by the above-mentioned method. After two and a half hours of decontamination, the decontamination factor made up approximately 400.
Decontamination of liquid radioactive wastes, obtained by the above-mentioned method, was carried out in the following way. Solution containing up to 0.1 g of potassium ferrocyanide was added to 1.0 litre of the solution being decontaminated, then the mixture was stirred and, by means of introduction of a mineral acid, solution pH was reduced down to coagulation of humus acids. The formed complex residue, mainly containing radioactive cesium and other radionuclides, was separated and iron sulphate solution was added to acid filtrate. Then, by means of adding alkali, pH was increased up to formation of flocculent, thus multivalent radionuclides were finally removed from the solution.
Liquid radioactive wastes, not containing humus substances, e.g., trap water or liquid radioactive wastes from special storage, may be also utilized by the proposed method by means of their alkalization (if necessary) and introduction of humus substances with subsequent utilization according to the scheme given in Example 6. In this case, liquid radioactive wastes from a special storage were decontaminated by the given method.
Results obtained in Examples 6 and 7 are given in Table 2.
Table 2 Results of decontamination of Liquid Radioactive Wastes SAMPLE Contents of Radionuclides, Bq/1 A total Cs-137 Co-60 Sr-90 Initial liquid radioactive 1.3E+4 9.3E+3 2.OE+3 6.OE+2 wastes (Example 6) 4.8E+2 7.4 3.3E+2 9.3 After decontamination Initial liquid radioactive 9.3E+4 4.8E+4 l .0E+3 2.2E+4 wastes (Example 7) 5.2E+2 1.3E+2 56 9.3 After decontamination Permissible concentration 5.6E+2 2.OE+3 14.8 of radionuclides in potable water Note: contamination levels for Mn-54 and Ru-106 are not given as in initial liquid radioactive wastes they were found to be within the permissible concentration of radionuclides in potable water.
A working piece of the primary circuit of nuclear reactor (a return valve), which had (3-radiation activity of 3000 particles/cmz min, was subject to decontamination by the above-mentioned method. After two and a half hours of decontamination, the decontamination factor made up approximately 400.
Decontamination of liquid radioactive wastes, obtained by the above-mentioned method, was carried out in the following way. Solution containing up to 0.1 g of potassium ferrocyanide was added to 1.0 litre of the solution being decontaminated, then the mixture was stirred and, by means of introduction of a mineral acid, solution pH was reduced down to coagulation of humus acids. The formed complex residue, mainly containing radioactive cesium and other radionuclides, was separated and iron sulphate solution was added to acid filtrate. Then, by means of adding alkali, pH was increased up to formation of flocculent, thus multivalent radionuclides were finally removed from the solution.
Liquid radioactive wastes, not containing humus substances, e.g., trap water or liquid radioactive wastes from special storage, may be also utilized by the proposed method by means of their alkalization (if necessary) and introduction of humus substances with subsequent utilization according to the scheme given in Example 6. In this case, liquid radioactive wastes from a special storage were decontaminated by the given method.
Results obtained in Examples 6 and 7 are given in Table 2.
Table 2 Results of decontamination of Liquid Radioactive Wastes SAMPLE Contents of Radionuclides, Bq/1 A total Cs-137 Co-60 Sr-90 Initial liquid radioactive 1.3E+4 9.3E+3 2.OE+3 6.OE+2 wastes (Example 6) 4.8E+2 7.4 3.3E+2 9.3 After decontamination Initial liquid radioactive 9.3E+4 4.8E+4 l .0E+3 2.2E+4 wastes (Example 7) 5.2E+2 1.3E+2 56 9.3 After decontamination Permissible concentration 5.6E+2 2.OE+3 14.8 of radionuclides in potable water Note: contamination levels for Mn-54 and Ru-106 are not given as in initial liquid radioactive wastes they were found to be within the permissible concentration of radionuclides in potable water.
Claims (8)
1. A method for decontamination of metal surfaces with deep and surface radioactive contamination, based on electrochemical effect of a special electrolyte solution on the surface being decontaminated, characterized in that, that with the purpose of destruction of oxide films on metal surface and release of radioactive substances from inner layers and their subsequent transfer into the solution, an electrode couple is used in electrolyte medium containing alkaline suspension of humus substances, serving as complex formers of radionuclides thereby simplifying the utilization of used liquid radioactive wastes by means of obtaining and separating the formed solid radioactive residue, and its ashing.
2. A method as per claim 1 characterized in that solutions of alkaline metals salts are used in the capacity of electrolyte.
3. A method as per claim 1 characterized in that hydroxides or carbonates of alkaline metals are used as alkalization agents.
4. A method as per claims 1 - 3 characterized in that, that with the purpose of increasing the decontamination efficiency, the electrolyte temperature is increased above ambient temperature.
5. A method as per claims 1 - 4 characterized in that, that with the purpose of increasing the decontamination efficiency, the electrolyte solution is pre-electrolyzed.
6. A method as per claims 1 - 5 characterized in that that potassium ferro-cyanide is additionally introduced into the solution with the purpose of increasing the efficiency of decontamintion of formed liquid radioactive wastes.
7. A method as per claims 1 - 6 characterized in that that iron salts are introduced into the solution and pH is increased up to formation of flocculent with the purpose of increasing the efficiency of removal of two and more valent radionuclides.
8. A method as per claim 7 characterized in that that chlorides and sulphate are used in the capacity of iron salts.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002265413A CA2265413A1 (en) | 1999-03-15 | 1999-03-15 | A method for complex decontamination of metal surfaces with deep and surface contamination and of liquid radioactive wastes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002265413A CA2265413A1 (en) | 1999-03-15 | 1999-03-15 | A method for complex decontamination of metal surfaces with deep and surface contamination and of liquid radioactive wastes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2265413A1 true CA2265413A1 (en) | 2000-09-15 |
Family
ID=29588563
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002265413A Abandoned CA2265413A1 (en) | 1999-03-15 | 1999-03-15 | A method for complex decontamination of metal surfaces with deep and surface contamination and of liquid radioactive wastes |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2265413A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3792936A4 (en) * | 2018-05-11 | 2023-01-04 | Joint Stock Company "Rosenergoatom" | Assembly for the electrochemical decontamination of metallic radioactive waste |
-
1999
- 1999-03-15 CA CA002265413A patent/CA2265413A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3792936A4 (en) * | 2018-05-11 | 2023-01-04 | Joint Stock Company "Rosenergoatom" | Assembly for the electrochemical decontamination of metallic radioactive waste |
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