CN117587278A - Process for extracting plutonium-238 from irradiated neptunium target and recovering neptunium-237 - Google Patents
Process for extracting plutonium-238 from irradiated neptunium target and recovering neptunium-237 Download PDFInfo
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- 229910052781 Neptunium Inorganic materials 0.000 title claims abstract description 89
- LFNLGNPSGWYGGD-UHFFFAOYSA-N neptunium atom Chemical compound [Np] LFNLGNPSGWYGGD-UHFFFAOYSA-N 0.000 title claims abstract description 89
- 238000000034 method Methods 0.000 title claims abstract description 62
- 230000008569 process Effects 0.000 title claims abstract description 36
- OYEHPCDNVJXUIW-VENIDDJXSA-N plutonium-238 Chemical compound [238Pu] OYEHPCDNVJXUIW-VENIDDJXSA-N 0.000 title claims abstract description 35
- LFNLGNPSGWYGGD-IGMARMGPSA-N neptunium-237 Chemical compound [237Np] LFNLGNPSGWYGGD-IGMARMGPSA-N 0.000 title claims abstract description 29
- 239000007789 gas Substances 0.000 claims abstract description 63
- 229910052778 Plutonium Inorganic materials 0.000 claims abstract description 51
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 claims abstract description 51
- 238000003682 fluorination reaction Methods 0.000 claims abstract description 15
- USCBBUFEOOSGAJ-UHFFFAOYSA-J tetrafluoroplutonium Chemical compound F[Pu](F)(F)F USCBBUFEOOSGAJ-UHFFFAOYSA-J 0.000 claims abstract description 14
- LBSYETUDXXNILO-UHFFFAOYSA-H neptunium hexafluoride Chemical compound F[Np](F)(F)(F)(F)F LBSYETUDXXNILO-UHFFFAOYSA-H 0.000 claims abstract description 13
- 239000008188 pellet Substances 0.000 claims abstract description 12
- OJSBUHMRXCPOJV-UHFFFAOYSA-H plutonium hexafluoride Chemical compound F[Pu](F)(F)(F)(F)F OJSBUHMRXCPOJV-UHFFFAOYSA-H 0.000 claims abstract description 12
- 238000000746 purification Methods 0.000 claims abstract description 12
- 238000000605 extraction Methods 0.000 claims abstract description 9
- 230000004992 fission Effects 0.000 claims abstract description 6
- 238000011282 treatment Methods 0.000 claims description 16
- 230000009467 reduction Effects 0.000 claims description 13
- 238000009283 thermal hydrolysis Methods 0.000 claims description 12
- 239000011261 inert gas Substances 0.000 claims description 11
- 230000001131 transforming effect Effects 0.000 claims description 10
- UTDLAEPMVCFGRJ-UHFFFAOYSA-N plutonium dihydrate Chemical compound O.O.[Pu] UTDLAEPMVCFGRJ-UHFFFAOYSA-N 0.000 claims description 9
- FLDALJIYKQCYHH-UHFFFAOYSA-N plutonium(IV) oxide Inorganic materials [O-2].[O-2].[Pu+4] FLDALJIYKQCYHH-UHFFFAOYSA-N 0.000 claims description 9
- QKUTVYUEUPNRBO-UHFFFAOYSA-N [O--].[O--].[Np+4] Chemical compound [O--].[O--].[Np+4] QKUTVYUEUPNRBO-UHFFFAOYSA-N 0.000 claims description 8
- 229910000478 neptunium(IV) oxide Inorganic materials 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 6
- QKCGXXHCELUCKW-UHFFFAOYSA-N n-[4-[4-(dinaphthalen-2-ylamino)phenyl]phenyl]-n-naphthalen-2-ylnaphthalen-2-amine Chemical compound C1=CC=CC2=CC(N(C=3C=CC(=CC=3)C=3C=CC(=CC=3)N(C=3C=C4C=CC=CC4=CC=3)C=3C=C4C=CC=CC4=CC=3)C3=CC4=CC=CC=C4C=C3)=CC=C21 QKCGXXHCELUCKW-UHFFFAOYSA-N 0.000 claims description 6
- 238000011084 recovery Methods 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 abstract description 21
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 13
- 239000002901 radioactive waste Substances 0.000 abstract description 6
- 238000000926 separation method Methods 0.000 abstract description 4
- XJSJJZSJUJFCRM-UHFFFAOYSA-N neptunium plutonium Chemical compound [Np].[Pu] XJSJJZSJUJFCRM-UHFFFAOYSA-N 0.000 abstract description 3
- 230000000694 effects Effects 0.000 abstract description 2
- 230000005855 radiation Effects 0.000 abstract 1
- 238000009423 ventilation Methods 0.000 description 8
- 150000003839 salts Chemical class 0.000 description 5
- 238000003608 radiolysis reaction Methods 0.000 description 4
- 229910052593 corundum Inorganic materials 0.000 description 3
- 239000010431 corundum Substances 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 3
- 230000002285 radioactive effect Effects 0.000 description 3
- 239000002910 solid waste Substances 0.000 description 3
- 239000002915 spent fuel radioactive waste Substances 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000005273 aeration Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000003758 nuclear fuel Substances 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- SOLQLNAXKAQIPH-UHFFFAOYSA-J [F-].[F-].[F-].[F-].[Np+4] Chemical compound [F-].[F-].[F-].[F-].[Np+4] SOLQLNAXKAQIPH-UHFFFAOYSA-J 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910001987 mercury nitrate Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- ALTWGIIQPLQAAM-UHFFFAOYSA-N metavanadate Chemical compound [O-][V](=O)=O ALTWGIIQPLQAAM-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- DRXYRSRECMWYAV-UHFFFAOYSA-N nitrooxymercury Chemical compound [Hg+].[O-][N+]([O-])=O DRXYRSRECMWYAV-UHFFFAOYSA-N 0.000 description 1
- 239000012074 organic phase Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000010815 organic waste Substances 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21G—CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES
- G21G1/00—Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation or particle bombardment, e.g. producing radioactive isotopes
- G21G1/02—Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation or particle bombardment, e.g. producing radioactive isotopes in nuclear reactors
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/005—Preliminary treatment of scrap
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B60/00—Obtaining metals of atomic number 87 or higher, i.e. radioactive metals
- C22B60/02—Obtaining thorium, uranium, or other actinides
- C22B60/0295—Obtaining thorium, uranium, or other actinides obtaining other actinides except plutonium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B60/00—Obtaining metals of atomic number 87 or higher, i.e. radioactive metals
- C22B60/02—Obtaining thorium, uranium, or other actinides
- C22B60/04—Obtaining plutonium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/001—Dry processes
- C22B7/002—Dry processes by treating with halogens, sulfur or compounds thereof; by carburising, by treating with hydrogen (hydriding)
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Environmental & Geological Engineering (AREA)
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- General Engineering & Computer Science (AREA)
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Abstract
The invention relates to a process for extracting plutonium-238 from an irradiated neptunium target and for recovering neptunium-237, comprising the following steps: firstly, converting the oxide of neptunium in the neptunium target pellet after irradiation into neptunium hexafluoride and converting the oxide of plutonium into plutonium tetrafluoride through first fluorinated gas to realize neptunium extraction; introducing the first fluorinated gas carrying neptunium hexafluoride into a cold trap for collection and purification to obtain a neptunium product; then further converting the plutonium tetrafluoride into plutonium hexafluoride gas through the second fluorinated gas, and realizing plutonium extraction; the plutonium hexafluoride carried by the second fluorinated gas is introduced into a cold trap for collection and purification, and a plutonium product is obtained; finally, treating and disposing of fission products; the existing process for extracting plutonium-238 and recovering neptunium-237 from the irradiated neptunium target can be changed essentially by a fluorination volatilization method by utilizing the reaction characteristics of two different fluorinated gases and neptunium; the method can simplify the flow, reduce the equipment scale, avoid using organic reagents, reduce the amount of radioactive waste, solve the problem of severe radiation and improve the neptunium-plutonium separation effect.
Description
Technical Field
The invention belongs to the technical field of nuclear fuel post-treatment, and particularly relates to a process method for extracting plutonium-238 from an irradiated neptunium target and recovering neptunium-237.
Background
The heat source and the isotope battery made of plutonium-238 have the advantages of high power density, long half-life, low toxicity, few harmful impurities (high-energy neutrons and high-energy gamma are not generated), simple protection, light shielding and the like. Therefore, the heat source and the isotope battery manufactured by the material have wide application in a plurality of severe environments, such as aerospace, extremely cold areas and the like. But is provided with 238 Pu does not exist in nature and can only be produced artificially by means of reactor irradiation 238 Pu. The usual methods are: recovery from spent fuel post-treatment 237 Np, recovered 237 Np is made into neptunium-237 target (aluminium, magnesium matrix) and then is put into reactor for irradiation, and the irradiated neptunium target is subjected to a plurality of chemical and chemical treatments to extract plutonium-238 and recover neptunium-237.
There are few existing processes for extracting plutonium-238 and recovering neptunium-237, including chinese patent CN111020244a, which discloses a "method for extracting and separating plutonium-238 from an irradiated neptunium target and recovering neptunium-237". The method is a water process flow for separating and extracting the plutonium from neptunium by a solvent extraction method. However, the process uses a large amount of organic solvent, which results in problems of large equipment scale, large amount of waste liquid (especially organic waste liquid), complex process flow and the like. Meanwhile, due to the strong alpha radioactivity of the plutonium-238, the plutonium-238 is seriously decomposed by irradiation of an organic reagent, so that the service life of the reagent is reduced, and meanwhile, the produced radiolysis product also has an influence on the purification of neptunium plutonium products; also, the inorganization of the waste organic phase is a problem in post-treatment. In addition, the aqueous process flow can use a large amount of salt-containing reagents such as metavanadate, silver nitrate, mercury nitrate and the like in the treatment process, so that the amount of radioactive wastes is greatly increased.
The fluorovolatilization method is one of the post-treatment methods of spent fuel, especially when treating molten salt reactor fuel. As early as 60 s of the 20 th century, the united states completed the separation verification of irradiated fuels by the fluorination volatilization method. Russian established a flow of a fluorination volatilization process for BOR-60 reactor spent fuel. In recent years, the technology of separation by volatilization of fluorination is developed in Czech and Japan, and a dry-wet method combined process FLUOREX is proposed. The fluorinated gases used in these schemes are mainly F 2 And HF predominate.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a process method for extracting plutonium-238 from an irradiated neptunium target and recovering neptunium-237, which essentially changes the process for extracting the plutonium-238 from the irradiated neptunium target and recovering neptunium-237 by a fluorination volatilization method, and can solve the problem of serious radiolysis in the process of extracting the plutonium-238 while simplifying the flow, reducing the equipment scale, not using organic reagents and reducing the amount of radioactive wastes; and can solve a series of problems caused by organic reagent treatment, reduce the use of salt-containing reagents, and further reduce the amount of radioactive solid waste.
In order to achieve the above purpose, the invention adopts the technical scheme that: a process for extracting plutonium-238 from an irradiated neptunium target and recovering neptunium-237, said process comprising the steps of:
s1, neptunium is extracted: the method comprises the steps of placing neptunium target pellets after irradiation into a reactor, introducing first fluorinated gas into the reactor, carrying out fluorination treatment on the neptunium target pellets after irradiation at a first set temperature, and converting oxides of neptunium in the neptunium target pellets after irradiation into neptunium hexafluoride and converting oxides of plutonium into plutonium tetrafluoride; the first fluorinated gas carrying neptunium hexafluoride enters a step S2 to collect and purify neptunium products; while the plutonium remains in the reactor in the form of plutonium tetrafluoride, ready to go to step S3 to extract the plutonium;
s2, collecting and purifying neptunium products: introducing the neptunium hexafluoride carried by the first fluorinated gas into a cold trap for collection and purification to obtain a neptunium product;
s3, extracting plutonium: introducing a second fluorinated gas into the reactor, continuously carrying out fluorination treatment on the irradiated neptunium target pellets at a second set temperature, and further converting the plutonium tetrafluoride into plutonium hexafluoride gas, wherein the second fluorinated gas carries the plutonium hexafluoride and enters a step S4 for collecting and purifying plutonium products;
s4: collecting and purifying plutonium products: introducing the plutonium hexafluoride carried by the second fluorinated gas into a cold trap for collection and purification to obtain a plutonium product;
s5, processing and disposing the fission product.
Further, the first fluorinated gas is a mixture of nitrogen trifluoride and an inert gas selected from N 2 One or two of Ar.
Further, in the first fluorinated gas, the volume percentage content of nitrogen trifluoride is not less than 5%.
Further, the first set temperature is 450 ℃ to 700 ℃.
Further, step S2 includes the following steps: and (3) transforming the neptunium product, and transforming the neptunium product into neptunium dioxide by adopting a thermal hydrolysis reduction mode.
Further, the second fluorinated gas is a mixed gas of fluorinated functional gas and inert gas;
the inert gas is selected from N 2 One or two of Ar and Ar;
the fluorinated functional gas comprises F 2 、HF、O 2 F 2 And the like.
Further, in the second fluorinated gas, the volume percentage content of the fluorinated functional gas is not less than 50%.
Further, the second set temperature is 300 ℃ or higher.
Further, step S4 includes the following steps: and transforming the plutonium product into plutonium dioxide by adopting a thermal hydrolysis reduction mode.
Further, the temperature of the thermal hydrolysis reduction is higher than 600 ℃.
The invention has the beneficial effects that the process method for extracting plutonium-238 from the irradiation neptunium target and recovering neptunium-237 provided by the invention comprises the following steps: firstly, converting the oxide of neptunium in the neptunium target pellet after irradiation into neptunium hexafluoride and converting the oxide of plutonium into plutonium tetrafluoride through first fluorinated gas to realize neptunium extraction; introducing the first fluorinated gas carrying neptunium hexafluoride into a cold trap for collection and purification to obtain a neptunium product; then further converting the plutonium tetrafluoride into plutonium hexafluoride gas through the second fluorinated gas, and realizing plutonium extraction; the plutonium hexafluoride carried by the second fluorinated gas is introduced into a cold trap for collection and purification, and a plutonium product is obtained; finally, treating and disposing of fission products; the process for extracting plutonium-238 and recovering neptunium-237 from the irradiated neptunium target is changed essentially by utilizing the reaction characteristics of two different fluorinated gases and neptunium by a fluorinated volatilization method, so that the flow can be simplified, the equipment scale can be reduced, and the neptunium separating effect can be greatly improved. In addition, the method provided by the invention adopts a dry process flow, so that the method does not need to use an organic reagent, reduces the amount of radioactive waste, and fundamentally solves the problem of serious alpha radiolysis in the plutonium-238 extraction process; and a series of problems caused by the subsequent treatment of the waste organic reagent can be solved, the use of the salt-containing reagent is reduced, and the amount of radioactive solid waste is greatly reduced.
Drawings
Fig. 1 is a schematic flow chart of a process for extracting plutonium-238 from an irradiated neptunium target and recovering neptunium-237 according to an embodiment of the present invention.
Detailed Description
The technical solutions of the embodiments of the present invention will be further clearly and completely described below with reference to the accompanying drawings and examples, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and all other examples obtained by those skilled in the art without making creative efforts based on the examples in the present invention are included in the protection scope of the present invention.
Plutonium-238 has important applications in national economy production, defense construction, etc., and it is particularly important to extract plutonium-238 and recover neptunium-237 from irradiated neptunium targets safely, efficiently, and with as little radioactive waste as possible.
In the embodiment of the invention, the process for extracting the plutonium-238 and recovering the neptunium-237 from the irradiated neptunium target is essentially changed by a fluorination volatilization method, so that the problem of serious radiolysis in the process of extracting the plutonium-238 can be solved while simplifying the flow, reducing the equipment scale, not using an organic reagent and reducing the amount of radioactive waste; and can solve a series of problems caused by organic reagent treatment, reduce the use of salt-containing reagents, and further reduce the amount of radioactive solid waste.
As shown in fig. 1, an embodiment of the present invention provides a process for extracting plutonium-238 from an irradiated neptunium target and recovering neptunium-237, said process comprising the steps of:
s1, neptunium is extracted: the neptunium target core blocks after irradiation are put into a reactor, first fluorinated gas is introduced into the reactor, fluorination treatment is carried out on the neptunium target core blocks after irradiation at a first set temperature, and each metal oxide in the neptunium target core blocks after irradiation is converted into fluoride; wherein the oxide of neptunium is converted to neptunium hexafluoride and the oxide of plutonium is converted to plutonium tetrafluoride; because neptunium hexafluoride is gas, under the carrier band of the first introduced fluorinated gas, the neptunium is collected and purified in the step S2, and neptunium extraction is realized; while the plutonium remains in the reactor in the form of plutonium tetrafluoride together with most of the fissile elements, ready to enter step S3 to extract the plutonium, effecting neptunium plutonium separation.
Specifically, in step S1, neptunium is extracted using a fluorinated volatilization method.
Specifically, in step S1, the first fluorinated gas is nitrogen trifluoride (NF 3 ) A gas mixture with an inert gas selected from the group consisting of N 2 One or two of Ar, etc., but not limited thereto.
In a specific embodiment, in the first fluorinated gas, nitrogen trifluoride (NF 3 ) The volume percentage content of the inert gas is not less than 5 percent, and the volume percentage content of the inert gas is 0-50 percent.
Optionally, the first set temperature is selected from 450 ℃ to 700 ℃.
Optionally, in step S1, the ventilation duration of the first fluorinated gas is not less than 1.5h, that is, the duration of step S1 for extracting neptunium by using a fluorination volatilization method, and neptunium is fluorinated and volatilized in this duration.
S2, collecting and purifying neptunium products: introducing the neptunium hexafluoride carried by the first fluorinated gas into a cold trap for collection and purification to obtain a neptunium product;
specifically, the neptunium product has a main component of neptunium tetrafluoride.
Specifically, step S2 further includes the following steps: and (3) transforming the neptunium product, and transforming the neptunium product into neptunium dioxide by adopting a thermal hydrolysis reduction mode.
In particular, the temperature of the thermal hydrolysis reduction should be higher than 600 ℃.
In a specific embodiment, the conversion of the neptunium product into neptunium dioxide by means of thermal hydrolysis reduction comprises the following specific steps: the neptunium product is placed in a reaction kettle, the temperature of the reaction kettle is kept at about 900 ℃, and water vapor and hydrogen (H) are introduced 2 The volume content is 2 percent) and the ventilation time is 2 hours, and the ventilation is stopped. The conversion rate of neptunium dioxide is detected to be higher than 99%.
S3, extracting plutonium: after stopping introducing the first fluorinated gas, introducing a second fluorinated gas into the reactor, continuing to perform fluorination treatment on the irradiated neptunium target pellets at a second set temperature, further converting the plutonium converted into plutonium tetrafluoride into plutonium hexafluoride gas, and under the carrier band of the introduced second fluorinated gas, entering a step S4 to collect and purify plutonium products so as to extract the plutonium.
Specifically, in step S3, plutonium is extracted by a fluorinated volatilization method.
Specifically, in step S3, the second fluorinated gas is a mixed gas of a fluorinated functional gas and an inert gas, where the inert gas is selected from N 2 One or two of Ar, etc., but not limited thereto; the fluorinated functional gas comprises F 2 、HF、O 2 F 2 And the like, but is not limited thereto.
In a specific embodiment, the volume percentage of the fluorinated functional gas in the second fluorinated gas is not less than 50%.
Optionally, the second set temperature is above 300 ℃.
Optionally, in step S1, the ventilation duration of the second fluorinated gas is 2-6 hours, that is, the duration of extracting the plutonium in step S3 by using a fluorination volatilization method, and the fluorination volatilization of the plutonium is completed in the duration.
S4: collecting and purifying plutonium products: introducing the plutonium hexafluoride carried by the second fluorinated gas into a cold trap for collection and purification to obtain a plutonium product;
specifically, the main component of the plutonium product is plutonium tetrafluoride.
Specifically, step S4 further includes the following steps: and transforming the plutonium product into plutonium dioxide by adopting a thermal hydrolysis reduction mode.
In particular, the temperature of the thermal hydrolysis reduction should be higher than 600 ℃.
In a specific embodiment, the conversion of the plutonium product into plutonium dioxide by means of thermal hydrolytic reduction comprises the following specific steps: putting the plutonium product into a reaction kettle, preserving the temperature of the reaction kettle to about 900 ℃, and introducing steam and hydrogen (H) 2 The volume content is 2 percent) and the ventilation time is 2 hours, and the ventilation is stopped. The conversion of plutonium dioxide was detected to be higher than 99%.
S5, processing and disposing fission products: i.e. to treat and dispose of the fission products of the irradiated neptunium target pellet remaining in the reactor.
Example 1
In this example 1, the process for extracting plutonium-238 from the neptunium target and recovering neptunium-237 according to the present embodiment was used to separate and recover plutonium from a mixture of neptunium dioxide and plutonium dioxide (neptunium dioxide 2g, 0.2g dioxide), and comprises the steps of:
s11, neptunium is extracted: placing the mixture of neptunium dioxide and plutonium dioxide in a reaction vessel, and placing the reaction vessel in a reaction kettle; the reaction kettle is kept at about 500 ℃ and is introduced with NF 3 Mixed gas of Ar (NF therein 3 Is 10% by volume) The aeration period was 1.5h, the neptunium in NpF 6 In the form of (c) escape.
S12, collecting and purifying neptunium products: NF is carried out 3 NpF of carrier tape 6 Introducing the neptunium into a cold trap for collection and purification to obtain a neptunium product; neptunium yields higher than 99% and neptunium/plutonium ratios higher than 3×10 in neptunium products 6 。
S13, extracting plutonium: stopping the NF 3 Then the reaction kettle is insulated at about 360 ℃ and is filled with pure F 2 The aeration period was 4h, with plutonium PuF 6 In the form of (c) escape.
S14: collecting and purifying plutonium products: will F 2 PuF of the Carrier tape 6 Collecting and purifying in cold trap to obtain plutonium product PuF 4 The method comprises the steps of carrying out a first treatment on the surface of the Plutonium yields higher than 98% and plutonium/neptunium ratios higher than 1X 10 in the plutonium product 6 。
Example 2
In this example 2, the plutonium product obtained in example 1 was transformed into plutonium dioxide by means of thermal hydrolysis reduction, comprising the steps of:
s21, taking 0.1g of the plutonium product PuF obtained in step S14 4 Placing the corundum reaction vessel in a corundum reaction vessel, and placing the corundum reaction vessel in a reaction kettle;
s22, transforming the plutonium product: the reaction kettle is kept at about 900 ℃ and is filled with water vapor and hydrogen (H) at a flow rate of 25ml/min 2 The volume content is 2 percent) and the ventilation time is 2 hours, and the ventilation is stopped. The conversion of plutonium dioxide was detected to be higher than 99%.
The method of the present invention is not limited to the specific embodiments described above, but the above examples are merely illustrative of the present invention, and the present invention may be embodied in other specific forms or in other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention should be indicated by the appended claims, and any changes that are equivalent to the intent and scope of the claims are intended to be encompassed within the scope of the invention.
Claims (10)
1. A process for extracting plutonium-238 from an irradiated neptunium target and for recovering neptunium-237, characterized in that it comprises the steps of:
s1, neptunium is extracted: the method comprises the steps of placing neptunium target pellets after irradiation into a reactor, introducing first fluorinated gas into the reactor, carrying out fluorination treatment on the neptunium target pellets after irradiation at a first set temperature, and converting oxides of neptunium in the neptunium target pellets after irradiation into neptunium hexafluoride and converting oxides of plutonium into plutonium tetrafluoride; the first fluorinated gas carrying neptunium hexafluoride enters a step S2 to collect and purify neptunium products; while the plutonium remains in the reactor in the form of plutonium tetrafluoride, ready to go to step S3 to extract the plutonium;
s2, collecting and purifying neptunium products: introducing the neptunium hexafluoride carried by the first fluorinated gas into a cold trap for collection and purification to obtain a neptunium product;
s3, extracting plutonium: introducing a second fluorinated gas into the reactor, continuously carrying out fluorination treatment on the irradiated neptunium target pellets at a second set temperature, and further converting the plutonium tetrafluoride into plutonium hexafluoride gas, wherein the second fluorinated gas carries the plutonium hexafluoride and enters a step S4 for collecting and purifying plutonium products;
s4: collecting and purifying plutonium products: introducing the plutonium hexafluoride carried by the second fluorinated gas into a cold trap for collection and purification to obtain a plutonium product;
s5, processing and disposing the fission product.
2. A process for extracting plutonium-238 and recovering neptunium-237 from an irradiated neptunium target according to claim 1, characterized in that said first fluorinated gas is a mixture of nitrogen trifluoride and an inert gas selected from N 2 One or two of Ar.
3. A process for the extraction of plutonium-238 and the recovery of neptunium-237 from a target of irradiated neptunium according to claim 2, characterized in that the first fluorinated gas has a volume percentage of nitrogen trifluoride not lower than 5%.
4. A process for the extraction of plutonium-238 from a target of irradiated neptunium and the recovery of neptunium-237 according to claim 1, characterized in that said first set temperature is comprised between 450 ℃ and 700 ℃.
5. A process for extracting plutonium-238 and recovering neptunium-237 from a target of irradiated neptunium according to claim 1, characterized in that step S2 comprises the following further steps: and (3) transforming the neptunium product, and transforming the neptunium product into neptunium dioxide by adopting a thermal hydrolysis reduction mode.
6. A process for extracting plutonium-238 from an irradiated neptunium target and for the recovery of neptunium-237 according to claim 1, characterized in that said second fluorinated gas is a mixture of a fluorinated functional gas and an inert gas;
the inert gas is selected from N 2 One or two of Ar and Ar;
the fluorinated functional gas comprises F 2 、HF、O 2 F 2 And the like.
7. A process for the extraction of plutonium-238 from an irradiated neptunium target and the recovery of neptunium-237, according to claim 6, characterized in that the volume percentage content of said fluorinated functional gas in said second fluorinated gas is not lower than 50%.
8. A process for extracting plutonium-238 and recovering neptunium-237 from a target of irradiated neptunium according to claim 5, characterized in that said second set temperature is above 300 ℃.
9. A process for extracting plutonium-238 and recovering neptunium-237 from a target of irradiated neptunium according to claim 1, characterized in that step S4 comprises the following further steps: and transforming the plutonium product into plutonium dioxide by adopting a thermal hydrolysis reduction mode.
10. A process for extracting plutonium-238 and recovering neptunium-237 from a target of irradiated neptunium according to claim 5 or 9, characterized in that: the temperature of the thermal hydrolysis reduction is higher than 600 ℃.
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