Simulation feed liquid for plutonium tail end precipitation reaction and determination method thereof

Abstract

The invention discloses a simulation feed liquid for plutonium tail end precipitation reaction and a determination method thereof, and the method comprises the following steps: according to the similarity of the precipitation reaction of a real material plutonium nitrate solution and an oxalic acid solution for the plutonium tail end precipitation reaction to generate a plutonium oxalate precipitate through a mixed reaction; the simulated feed liquid is determined to be a plutonium simulated element solution and a simulated oxalic acid solution, and the plutonium simulated element solution and the simulated oxalic acid solution are mixed and react to generate oxalate precipitate of the plutonium simulated element. The test method for determining the simulation feed liquid of the plutonium tail end precipitation reaction is developed, is good in simulation performance and high in operability, and can be applied to development, test, verification or preliminary debugging work of a precipitation reactor; several simulation feed liquid compositions and preparation methods are provided, the simulation performance is good, and the device is convenient to use in different working conditions and research stages; the invention provides a test method of the simulated feed liquid of the plutonium tail end precipitation reactor, which can be used for reference in development, research, acceptance and debugging of other plutonium-containing equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear fuel post-processing, and in particular relates to a simulated feed liquid for plutonium tail end precipitation reaction and a determination method thereof. Background Art

[0002] Nuclear fuel reprocessing plants mainly use the PUREX process. The plutonium tail is an important component process. Generally, the plutonium oxalate precipitation-filtration-roasting method is used to convert the plutonium nitrate solution into plutonium dioxide powder. Precipitation is a key process link in the plutonium tail. The precipitation reactor is the starting equipment of the plutonium tail and is also an important equipment for realizing the function of the plutonium tail. The precipitation product has a great influence on the quality of the plutonium product. The structure and performance of the precipitation reactor directly affect the subsequent filtration, drying and roasting process flow and equipment design and operation.

[0003] The essence of the precipitation reaction is the reaction of plutonium nitrate and oxalic acid to form plutonium oxalate hexahydrate crystals. The precipitation reactor is divided into two operating modes: batch and continuous. Experimental research is required when developing new equipment, and corresponding experimental verification or preliminary debugging is also required after the equipment is manufactured and before operation. Due to the strict management of plutonium and the extreme toxicity and radioactivity of plutonium, it is impossible to use real plutonium feed liquid to carry out the test, verification or preliminary debugging of the precipitation reactor. It is necessary to determine the selection method of the simulated feed liquid according to the characteristics of different plutonium tail precipitation reactors, select simulated feed liquid with good simulation and strong operability, and determine the simulated feed liquid test method for the precipitation reactor. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a simulated liquid for plutonium tail end precipitation reaction and a method for determining the same in view of the above-mentioned deficiencies in the prior art, so as to support the development of new equipment for precipitation reactors, functional verification after equipment manufacturing, and preliminary debugging.

[0005] The technical solution adopted to solve the technical problem of the present invention is to provide a test method for determining the simulated liquid of the plutonium tail precipitation reaction, comprising the following steps:

[0006] According to the similarity of the precipitation reaction of the real material plutonium tail-end precipitation reaction in the reprocessing plant, which is the mixture reaction of plutonium nitrate solution and oxalic acid solution to form plutonium oxalate precipitate, it is determined that the simulated feed liquids are respectively a solution of plutonium simulated element and a simulated oxalic acid solution, and a mixture of a solution of plutonium simulated element and a simulated oxalic acid solution, and the reaction forms an oxalate precipitate of plutonium simulated element.

[0007] Preferably, the plutonium simulating element is any one of Fe, Ce and U.

[0008] Preferably, the precipitation reaction is a precipitation crystallization reaction, and the similarity of the precipitation crystallization reaction refers to any one or more of the similarities of precipitation crystallization rate, aging time, crystal particle size, crystal density, crystal solubility of the product after precipitation crystallization, and properties of the simulated element of plutonium itself.

[0009] Preferably, the concentration of the real material plutonium nitrate solution is 10-100 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.2-0.8 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the concentration of nitric acid in the nitric acid system is 1.5-4 mol / L.

[0010] Preferably, the aging time of the mixed reaction of the real materials of the plutonium tail precipitation reaction in the post-processing plant, the plutonium nitrate solution and the oxalic acid solution, is no more than 3 hours, the particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 100 μm, and the density of the plutonium oxalate precipitate crystals is 1-3 kg / L.

[0011] Preferably, the aging time of the mixed reaction of the solution of the simulated element of plutonium and the simulated oxalic acid solution is no more than 3 hours, the particle size of the oxalate precipitate of the simulated element of plutonium generated by the reaction is no more than 100 μm, and the density of the oxalate precipitate of the simulated element of plutonium is 1 to 3 kg / L.

[0012] Preferably, the simulated feed solutions are ferrous sulfate solution and simulated oxalic acid solution, respectively, and the reaction generates ferrous oxalate precipitate.

[0013] Preferably, the ratio of the amounts of the simulated oxalic acid solution and the ferrous sulfate solution is (1.3-1.05):1.

[0014] Preferably, the simulated feed solutions are cerous nitrate solution and simulated oxalic acid solution, respectively, and the reaction generates cerous oxalate precipitate.

[0015] Preferably, the simulated feed solution cerous nitrate solution and the simulated oxalic acid solution react in a simulated nitric acid system, and the nitric acid concentration in the simulated nitric acid system does not exceed 3 mol / L.

[0016] Preferably, the ratio of the amounts of the simulated oxalic acid solution and the cerous nitrate solution is (1.8-1.55):1.

[0017] Preferably, the simulated feed solutions are respectively a uranium-containing solution and a simulated oxalic acid solution.

[0018] Preferably, the uranium-containing solution is a uranium nitrate solution and / or a uranyl nitrate solution, the uranium nitrate solution reacts with the simulated oxalic acid solution to generate a uranyl oxalate precipitate, and the uranyl nitrate solution and oxalic acid generate a uranyl oxalate precipitate.

[0019] Preferably, the ratio of the amounts of the simulated oxalic acid solution and the uranium nitrate solution is (2.15-2.45):1.

[0020] Preferably, the ratio of the amount of the simulated oxalic acid solution to the amount of the uranyl nitrate solution is (1.3-1.05):1.

[0021] Preferably, the simulated liquid uranyl nitrate solution and the simulated oxalic acid solution are reacted in a simulated nitric acid system, and the nitric acid concentration in the simulated nitric acid system does not exceed 1 mol / L.

[0022] Preferably, when reacting in a batch precipitation reactor, a batch of the entire plutonium simulated element solution is added to the batch precipitation reactor, and then the simulated oxalic acid solution is quantitatively added, and the simulated oxalic acid solution is added for 0.4 to 0.6 hours.

[0023] The present invention also provides a simulated feed solution for plutonium tail end precipitation reaction, which is determined by the above method.

[0024] The benefits of the simulated liquid for the plutonium tail precipitation reaction and the method for determining the same

[0025] The effect is as follows:

[0026] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0027] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0028] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0030] Example 1

[0031] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, comprising the following steps:

[0032] According to the similarity of the precipitation reaction of the real material plutonium tail-end precipitation reaction in the reprocessing plant, which is the mixture reaction of plutonium nitrate solution and oxalic acid solution to form plutonium oxalate precipitate, it is determined that the simulated feed liquids are respectively a solution of plutonium simulated element and a simulated oxalic acid solution, and a mixture of a solution of plutonium simulated element and a simulated oxalic acid solution, and the reaction forms an oxalate precipitate of plutonium simulated element.

[0033] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0034] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0035] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0036] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0037] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0038] Example 2

[0039] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, comprising the following steps:

[0040] According to the similarity of the precipitation reaction of the real material plutonium tail-end precipitation reaction in the reprocessing plant, which is the mixture reaction of plutonium nitrate solution and oxalic acid solution to form plutonium oxalate precipitate, it is determined that the simulated feed liquids are respectively a solution of plutonium simulated element and a simulated oxalic acid solution, and a mixture of a solution of plutonium simulated element and a simulated oxalic acid solution, and the reaction forms an oxalate precipitate of plutonium simulated element.

[0041] The technical solution of this embodiment is as follows: according to the characteristics of the precipitation reactor, a method for selecting a simulated feed liquid is proposed, a simulated feed liquid with good simulation and strong operability is provided, and a simulated feed liquid test method for the precipitation reactor is determined.

[0042] Preferably, the plutonium simulating element is any one of Fe, Ce and U.

[0043] Preferably, the precipitation reaction is a precipitation crystallization reaction, and the similarity of the precipitation crystallization reaction refers to any one or more of the similarities of precipitation crystallization rate, aging time, crystal particle size, crystal density, crystal solubility of the product after precipitation crystallization, and properties of the simulated element of plutonium itself.

[0044] The method for determining the simulated feed solution is based on the function of the precipitation reactor. Regardless of whether it is a batch or continuous precipitation reactor, its essence is a crystallization reaction, that is, a chemical reaction of precipitation and crystallization occurs after two solutions are mixed. The appropriate simulated feed solution is judged from the degree of similarity in terms of crystallization rate, aging time, crystal particle size of the product after crystallization, crystal density, crystal solubility, and the properties of the element itself.

[0045] Preferably, the concentration of the real material plutonium nitrate solution is 10-100 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.2-0.8 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the nitric acid concentration in the nitric acid system is 1.5-4 mol / L. The real material reacts in a precipitation reactor, and the ratio of oxalic acid and plutonium nitrate meets the requirements of stoichiometry, and oxalic acid is slightly excessive.

[0046] Preferably, the aging time of the mixed reaction of the real material plutonium nitrate solution and oxalic acid solution in the plutonium tail precipitation reaction in the post-processing plant is no more than 3 hours, the particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 100 μm, generally 60 to 100 μm, the density of the plutonium oxalate precipitate crystals is 1 to 3 kg / L, and the solubility of the plutonium oxalate precipitate crystals in the reaction environment is relatively low. The crystallization rate of the plutonium oxalate dihydrate precipitate generated by the reaction of plutonium nitrate and oxalic acid in the precipitation reactor is relatively fast.

[0047] Preferably, the aging time of the mixed reaction of the solution of the simulated element of plutonium and the simulated oxalic acid solution is no more than 3 hours, the particle size of the oxalate precipitate crystals of the simulated element of plutonium generated by the reaction is no more than 100 μm, generally 60 to 100 μm, and the density of the oxalate precipitate crystals of the simulated element of plutonium is 1 to 3 kg / L.

[0048] Preferably, the simulated feed solutions are ferrous sulfate solution and simulated oxalic acid solution, respectively, and the reaction generates ferrous oxalate precipitate.

[0049] Ferrous sulfate and oxalic acid generate ferrous sulfate heptahydrate in the precipitation reactor. The crystallization rate is at the same level as the real material. The aging time is no more than 3 hours. The crystal size is no more than 100 μm, generally 60 to 100 μm. The crystal density is 1 to 3 kg / L. The crystal has a low solubility in the reaction environment. Therefore, this simulated material can be used as a simulated material for the precipitation reactor. Sulfuric acid is generated after the reaction, and nitric acid does not need to be added to this simulated material system.

[0050] Preferably, the ratio of the amounts of the simulated oxalic acid solution and the ferrous sulfate solution is (1.3-1.05):1.

[0051] Ferrous sulfate solution and simulated oxalic acid solution, the mass concentration of ferrous sulfate solution should be consistent with the plutonium concentration. This is because the atomic mass of plutonium is large. If the same molar concentration is used, the converted iron mass is smaller, and the mass of the generated ferrous oxalate dihydrate is also smaller, and the simulation is not enough to cover the material; the molar concentration of the simulated oxalic acid solution is consistent with the real material; the ratio of oxalic acid to ferrous sulfate is based on a 1:1 molar ratio, with a slight excess of oxalic acid, and the molar ratio is generally (1.3~1.05):1.

[0052] Preferably, the simulated feed solutions are cerous nitrate solution and simulated oxalic acid solution, respectively, and the reaction generates cerous oxalate precipitate.

[0053] The simulated feed liquid of the precipitation reactor can be cerous nitrate solution and simulated oxalic acid solution. Cerous nitrate and oxalic acid generate cerous oxalate nonahydrate, and the crystallization rate is at the same order of magnitude as the real material, the aging time is not more than 3h, the crystal particle size is not more than 100μm, generally 60-100μm, the crystal density is 1-3kg / L, and the crystal solubility in the reaction environment is relatively low. And as a lanthanide element, cerium has similar atomic composition, outer electrons, chemical properties, etc. to the actinide element plutonium. Therefore, this simulated feed liquid can be used as a simulated feed liquid for the precipitation reactor.

[0054] Preferably, the simulated feed solution cerous nitrate solution and the simulated oxalic acid solution react in a simulated nitric acid system, and the nitric acid concentration in the simulated nitric acid system does not exceed 3 mol / L.

[0055] The solubility of cerous oxalate nonahydrate is similar to that of plutonium oxalate dihydrate in the absence of nitric acid. The solubility of cerous oxalate nonahydrate increases significantly with the increase of nitric acid concentration, and its increase is much greater than that of plutonium oxalate dihydrate. Therefore, when cerous nitrate and oxalic acid are used as simulated materials, it is not advisable to add additional nitric acid to the system. If nitric acid needs to be added, the concentration of nitric acid should not exceed 3 mol / L.

[0056] Preferably, the ratio of the amounts of the simulated oxalic acid solution and the cerous nitrate solution is (1.8-1.55):1.

[0057] The mass concentration of cerous nitrate and simulated oxalic acid solution should be consistent with the plutonium concentration. This is because the atomic mass of plutonium is large. If the same molar concentration is used, the converted cerium mass is smaller, and the mass of the generated cerous oxalate nonahydrate is also smaller, and the simulation is not enough to cover the material; the molar concentration of simulated oxalic acid is consistent with the real material; the ratio of simulated oxalic acid to cerous nitrate is based on the molar ratio of 1.5:1, with a slight excess of oxalic acid, and the molar ratio is generally (1.8~1.55):1.

[0058] Preferably, the simulated feed solutions are respectively a uranium-containing solution and a simulated oxalic acid solution.

[0059] Preferably, the uranium-containing solution is a uranium nitrate solution and / or a uranyl nitrate solution, the uranium nitrate solution reacts with the simulated oxalic acid solution to generate a uranyl oxalate precipitate, and the uranyl nitrate solution and oxalic acid generate a uranyl oxalate precipitate.

[0060] The solution containing uranium in the precipitation reactor includes uranium nitrate solution (uranium tetravalent) and / or uranyl nitrate solution (uranium hexavalent).

[0061] The uranium nitrate solution and oxalic acid generate uranium oxalate, and the uranyl nitrate solution and oxalic acid generate uranyl oxalate; the crystallization rate of uranium oxalate and uranyl oxalate is at the same level as the real material, the aging time is not more than 3 hours, the crystal particle size is not more than 100μm, generally 60-100μm; uranium and plutonium are both actinide elements, with similar atomic masses and some similar properties. Therefore, this simulated material can be used as a simulated material for a precipitation reactor.

[0062] Preferably, the ratio of the amounts of the simulated oxalic acid solution and the uranium nitrate solution is (2.15-2.45):1.

[0063] Preferably, the ratio of the amount of the simulated oxalic acid solution to the amount of the uranyl nitrate solution is (1.3-1.05):1.

[0064] The mass concentration / molar concentration of the uranium solution and the simulated oxalic acid solution should be consistent with that of plutonium, because the atomic masses of uranium and plutonium are close, and the masses are also close when the amount of substance is the same; the molar concentration of the simulated oxalic acid solution is consistent with the real material; the ratio of simulated oxalic acid to uranyl nitrate is based on the amount of substance of 2:1, and the simulated oxalic acid is slightly excessive, and the molar ratio is generally (2.15-2.45):1; the ratio of simulated oxalic acid to uranyl nitrate is based on the amount of substance of 1:1, and the simulated oxalic acid is slightly excessive, and the molar ratio is generally (1.3-1.05):1.

[0065] Preferably, the simulated liquid uranyl nitrate solution and the simulated oxalic acid solution are reacted in a simulated nitric acid system, and the nitric acid concentration in the simulated nitric acid system does not exceed 1 mol / L.

[0066] The particle size of uranyl oxalate is larger, which is more conducive to verifying the subsequent filtration operation. However, the solubility of uranyl oxalate is relatively large, especially in the nitric acid system. Therefore, when using uranyl nitrate solution and oxalic acid as simulation materials, additional nitric acid cannot be added to the system. When it must be added, its nitric acid concentration should not be greater than 1 mol / L.

[0067] Preferably, when reacting in a batch precipitation reactor, a batch of solutions of all plutonium simulating elements (Fe, Ce or U) are added to the batch precipitation reactor, and then a simulated oxalic acid solution is added quantitatively, and the simulated oxalic acid solution is added for 0.4 to 0.6 hours.

[0068] Furthermore, the test method for the simulated liquid feed of the plutonium tail precipitation reaction is determined. For a continuous precipitation reactor, according to the ratio of the simulated element of plutonium (Fe, Ce or U) and the simulated oxalic acid solution, the simulated element of plutonium (Fe, Ce or U) material and the simulated oxalic acid solution are quantitatively and simultaneously added to the continuous precipitation reactor. The operating conditions are the same or similar to those of the real material, and the addition process should be continuous and stable.

[0069] Furthermore, the test method for determining the simulated feed liquid for the plutonium tail precipitation reaction analyzes the crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the simulated material, and compares the actual analysis results with the theoretical values ​​or small experimental data of the precipitation reaction to determine whether the performance of the precipitation reactor meets the requirements. Generally, a deviation within 10% is acceptable. In special cases, a certain parameter can be appropriately adjusted to make the deviation within an acceptable deviation range.

[0070] Specifically, this embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, comprising the following steps:

[0071] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 15 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.3 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the nitric acid concentration in the initial nitric acid system is 2 mol / L.

[0072] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the plutonium nitrate solution and the oxalic acid solution, are mixed and aged for 3 hours. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 80μm, and the density of the plutonium oxalate precipitate crystals is 1.5-2.5kg / L.

[0073] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be ferrous sulfate solution and simulated oxalic acid solution respectively.

[0074] Equipment function verification phase:

[0075] The simulated liquid used was ferrous sulfate solution with an iron ion concentration of 15 g / L; the simulated oxalic acid solution concentration was 0.3 mol / L, and no additional nitric acid was added to the system. The molar ratio of simulated oxalic acid to ferrous sulfate was 1.1:1.

[0076] Test method: Add ferrous sulfate solution into the reactor, and then add oxalic acid solution quantitatively. The oxalic acid addition time is controlled within 20 to 30 minutes.

[0077] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 3 hours. The particle size of the ferrous oxalate dihydrate precipitate crystals generated by the reaction is not more than 80 μm, generally 60 to 100 μm, and the density of the ferrous oxalate dihydrate precipitate crystals is 1.5 to 2.5 kg / L.

[0078] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the produced ferrous oxalate dihydrate were analyzed, and the actual analysis results were compared with the theoretical values ​​of the real materials. The deviation was within 5%, indicating that the equipment performance met the requirements.

[0079] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0080] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0081] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0082] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0083] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0084] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0085] Example 3

[0086] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in Embodiment 2 in that it includes the following steps:

[0087] In a continuous precipitation reactor, the concentration of the real material plutonium nitrate solution based on the mass of plutonium is 60 g / L, the concentration of the real material oxalic acid solution is 0.7 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the nitric acid concentration in the initial nitric acid system is 3 mol / L.

[0088] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, has an aging time of 0.5h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 100μm, and the density of the plutonium oxalate precipitate crystals is 2-3kg / L.

[0089] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be cerous nitrate solution and simulated oxalic acid solution respectively.

[0090] New equipment development stage:

[0091] The simulated liquid used cerium nitrate solution with a cerium ion concentration of 60 g / L; the simulated oxalic acid concentration was 0.7 mol / L, and the initial nitric acid concentration in the system was 1 mol / L. The molar ratio of simulated oxalic acid and cerium nitrate was 1.7:1.

[0092] Test method: Cerous nitrate solution and simulated oxalic acid solution were added to the continuous precipitation reactor simultaneously and quantitatively.

[0093] The aging time of the mixed reaction of the simulated plutonium element solution and the simulated oxalic acid solution is 0.5h, the particle size of the cerous oxalate nonahydrate precipitate crystals generated by the reaction is not greater than 100μm, and the density of the cerous oxalate nonahydrate precipitate crystals is 2-3kg / L.

[0094] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated cerous oxalate nonahydrate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of the real material. The deviation was within 10%, indicating that the equipment performance met the requirements.

[0095] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0096] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0097] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0098] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0099] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0100] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0101] Example 4

[0102] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in Embodiment 2 in that it includes the following steps:

[0103] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 10 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.5 mol / L, the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 1.5 mol / L.

[0104] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the plutonium nitrate solution and the oxalic acid solution, are mixed and aged for 2 hours. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 60μm, and the density of the plutonium oxalate precipitate crystals is 1-2kg / L.

[0105] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be uranyl nitrate solution and simulated oxalic acid solution respectively.

[0106] Initial debugging stage of equipment:

[0107] The simulated liquid used uranyl nitrate solution with a uranyl ion concentration of 10 g / L; the simulated oxalic acid solution with a concentration of 0.5 mol / L was used, and no additional nitric acid was added to the system. The molar ratio of simulated oxalic acid to uranyl nitrate was 1.2:1.

[0108] Test method: Add uranyl nitrate solution into the reactor, and then add oxalic acid solution quantitatively. The oxalic acid addition time is controlled within 30 to 40 minutes.

[0109] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 2 hours, the particle size of the uranyl oxalate precipitate crystals generated by the reaction is not greater than 60 μm, and the density of the uranyl oxalate precipitate crystals is 1 to 2 kg / L.

[0110] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated uranyl oxalate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 8%, indicating that the equipment performance met the requirements.

[0111] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0112] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0113] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0114] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0115] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0116] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0117] Example 5

[0118] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 2 in that:

[0119] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 60 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.2 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 1.5 mol / L.

[0120] The aging time of the mixed reaction of the actual material plutonium nitrate solution and oxalic acid solution in the plutonium tail precipitation reaction in the reprocessing plant is 0.6h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is not more than 70μm, and the density of the plutonium oxalate precipitate crystals is 1.5-2.5kg / L.

[0121] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be ferrous sulfate solution and simulated oxalic acid solution respectively.

[0122] Equipment function verification phase:

[0123] The simulated liquid used was ferrous sulfate solution with an iron ion concentration of 60 g / L; the simulated oxalic acid solution concentration was 0.2 mol / L, and no additional nitric acid was added to the system. The molar ratio of simulated oxalic acid to ferrous sulfate was 1.05:1.

[0124] Test method: Add ferrous sulfate solution into the reactor, and then add oxalic acid solution quantitatively. The oxalic acid addition time is controlled within 0.6h.

[0125] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 0.6h, the particle size of the ferrous oxalate dihydrate precipitate crystals generated by the reaction is not greater than 70μm, and the density of the ferrous oxalate dihydrate precipitate crystals is 1.5-2.5kg / L.

[0126] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the produced ferrous oxalate dihydrate were analyzed, and the actual analysis results were compared with the theoretical values ​​of the real materials. The deviation was within 5%, indicating that the equipment performance met the requirements.

[0127] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0128] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0129] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0130] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0131] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0132] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0133] Example 6

[0134] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 2 in that:

[0135] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 100 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.8 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 4 mol / L.

[0136] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, has an aging time of 1.5h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 100μm, and the density of the plutonium oxalate precipitate crystals is 1-2kg / L.

[0137] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be ferrous sulfate solution and simulated oxalic acid solution respectively.

[0138] Equipment function verification phase:

[0139] The simulated liquid used ferrous sulfate solution with an iron ion concentration of 100 g / L; the simulated oxalic acid solution with a concentration of 0.8 mol / L was used, and no additional nitric acid was added to the system. The molar ratio of simulated oxalic acid to ferrous sulfate was 1.3:1.

[0140] Test method: Add ferrous sulfate solution into the reactor, and then add oxalic acid solution quantitatively. The oxalic acid addition time is controlled within 0.4h.

[0141] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 1.5 hours. The particle size of the ferrous oxalate dihydrate precipitate crystals generated by the reaction is not more than 100 μm, generally 60 to 100 μm, and the density of the ferrous oxalate dihydrate precipitate crystals is 1 to 2 kg / L.

[0142] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the produced ferrous oxalate dihydrate were analyzed, and the actual analysis results were compared with the theoretical values ​​of the real materials. The deviation was within 7%, indicating that the equipment performance met the requirements.

[0143] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0144] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0145] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0146] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0147] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0148] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0149] Example 7

[0150] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 2 in that:

[0151] In a continuous precipitation reactor, the concentration of the real material plutonium nitrate solution is 10 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.8 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 3 mol / L.

[0152] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, is aged for 1 hour. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is not greater than 100μm, and the density of the plutonium oxalate precipitate crystals is 1-2kg / L.

[0153] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be cerous nitrate solution and simulated oxalic acid solution respectively.

[0154] New equipment development stage:

[0155] The simulated liquid used cerium nitrate solution with a cerium ion concentration of 10 g / L, the simulated oxalic acid concentration was 0.8 mol / L, and the initial nitric acid concentration in the system was 3 mol / L. The molar ratio of simulated oxalic acid and cerium nitrate was 1.8:1.

[0156] Test method: Cerous nitrate solution and simulated oxalic acid solution were added to the continuous precipitation reactor simultaneously and quantitatively.

[0157] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 1 hour, the particle size of the cerous oxalate nonahydrate precipitate crystals generated by the reaction is not greater than 100 μm, and the density of the cerous oxalate nonahydrate precipitate crystals is 1-2 kg / L.

[0158] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated cerous oxalate nonahydrate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 8%, indicating that the equipment performance met the requirements.

[0159] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0160] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0161] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0162] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0163] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0164] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0165] Example 8

[0166] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 2 in that:

[0167] In a continuous precipitation reactor, the concentration of the real material plutonium nitrate solution based on the mass of plutonium is 30 g / L, the concentration of the real material oxalic acid solution is 0.2 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the nitric acid concentration in the initial nitric acid system is 2 mol / L.

[0168] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, has an aging time of 2.5h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 60μm, and the density of the plutonium oxalate precipitate crystals is 1.5-2.5kg / L.

[0169] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be cerous nitrate solution and simulated oxalic acid solution respectively.

[0170] New equipment development stage:

[0171] The simulated liquid used cerium nitrate solution with a cerium ion concentration of 30 g / L; the simulated oxalic acid concentration was 0.2 mol / L, and the initial nitric acid concentration in the system was 2 mol / L. The molar ratio of simulated oxalic acid and cerium nitrate was 1.55:1.

[0172] Test method: Cerous nitrate solution and simulated oxalic acid solution were added to the continuous precipitation reactor simultaneously and quantitatively.

[0173] The aging time of the mixed reaction of the simulated plutonium element solution and the simulated oxalic acid solution is 2.5 hours, and the particle size of the cerous oxalate nonahydrate precipitate crystals generated by the reaction is not greater than 60 μm, and the density of the cerous oxalate nonahydrate precipitate crystals is 1.5-2.5 kg / L.

[0174] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated cerous oxalate nonahydrate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 9%, indicating that the equipment performance met the requirements.

[0175] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0176] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0177] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0178] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0179] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0180] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0181] Example 9

[0182] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 3 in that:

[0183] In a continuous precipitation reactor, the concentration of the real material plutonium nitrate solution is 100 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.6 mol / L, and the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid-free system.

[0184] The aging time of the real material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, is 1.2h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 100μm, and the density of the plutonium oxalate precipitate crystals is 2-3kg / L.

[0185] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be cerous nitrate solution and simulated oxalic acid solution respectively.

[0186] New equipment development stage:

[0187] The simulated liquid used cerium nitrate solution with a cerium ion concentration of 100 g / L, and the simulated oxalic acid concentration was 0.6 mol / L, and the reaction was carried out in a nitric acid-free system. The molar ratio of simulated oxalic acid and cerium nitrate was 1.7:1.

[0188] Test method: Cerous nitrate solution and simulated oxalic acid solution were added to the continuous precipitation reactor simultaneously and quantitatively.

[0189] The aging time of the mixed reaction of the simulated plutonium element solution and the simulated oxalic acid solution is 1.2 hours. The particle size of the cerous oxalate nonahydrate precipitate crystals generated by the reaction is not greater than 100 μm, and the density of the cerous oxalate nonahydrate precipitate crystals is 2-3 kg / L.

[0190] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated cerous oxalate nonahydrate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 6%, indicating that the equipment performance met the requirements.

[0191] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0192] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0193] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0194] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0195] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0196] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0197] Example 10

[0198] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 4 in that:

[0199] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 10 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.2 mol / L, the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 2.5 mol / L.

[0200] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, has an aging time of 0.5h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 90μm, and the density of the plutonium oxalate precipitate crystals is 1.5-2.5kg / L.

[0201] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be uranium nitrate solution and simulated oxalic acid solution respectively.

[0202] Initial debugging stage of equipment:

[0203] The simulated liquid used was uranyl nitrate solution with a uranyl ion concentration of 10 g / L; the simulated oxalic acid solution concentration was 0.2 mol / L, and the initial nitric acid concentration in the system was 2.5 mol / L. The molar ratio of simulated oxalic acid to uranium nitrate was 2.25:1.

[0204] Test method: Add uranium nitrate solution into the reactor, then add oxalic acid solution quantitatively, and the oxalic acid addition time is controlled within 0.6h.

[0205] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 0.5h, the particle size of the uranium oxalate precipitate crystals generated by the reaction is not greater than 90μm, and the density of the uranium oxalate precipitate crystals is 1.5-2.5kg / L.

[0206] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated uranium oxalate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 5%, indicating that the equipment performance met the requirements.

[0207] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0208] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0209] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0210] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0211] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0212] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0213] Embodiment 11

[0214] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 4 in that:

[0215] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 40 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.5 mol / L, the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid system, and the nitric acid concentration in the initial nitric acid system is 4 mol / L.

[0216] The aging time of the real material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, is 1.8h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 70μm, and the density of the plutonium oxalate precipitate crystals is 2-3kg / L.

[0217] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be uranium nitrate solution and simulated oxalic acid solution respectively.

[0218] Initial debugging stage of equipment:

[0219] The simulated liquid used was uranyl nitrate solution with a uranyl ion concentration of 40 g / L; the simulated oxalic acid solution concentration was 0.5 mol / L, and the initial nitric acid concentration in the system was 4 mol / L. The molar ratio of simulated oxalic acid to uranium nitrate was 2.3:1.

[0220] Test method: Add uranium nitrate solution into the reactor, then add oxalic acid solution quantitatively, and the oxalic acid addition time is controlled within 0.4h.

[0221] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 1.8 hours. The particle size of the uranium oxalate precipitate crystals generated by the reaction is not greater than 70 μm, and the density of the uranium oxalate precipitate crystals is 2 to 3 kg / L.

[0222] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated uranium oxalate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 7%, indicating that the equipment performance met the requirements.

[0223] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0224] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0225] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0226] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0227] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0228] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0229] Example 12

[0230] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 4 in that:

[0231] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 100 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.8 mol / L, the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 1.5 mol / L.

[0232] The aging time of the real material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, is 0.6h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is not more than 100μm, and the density of the plutonium oxalate precipitate crystals is 1-2kg / L.

[0233] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be uranium nitrate solution and simulated oxalic acid solution respectively.

[0234] Initial debugging stage of equipment:

[0235] The simulated liquid used uranium nitrate solution with a uranyl ion concentration of 100 g / L; the simulated oxalic acid solution with a concentration of 0.8 mol / L was used, and the initial nitric acid concentration in the system was 1.5 mol / L. The molar ratio of simulated oxalic acid to uranium nitrate was 2.35:1.

[0236] Test method: Add uranium nitrate solution into the reactor, then add oxalic acid solution quantitatively, and the oxalic acid addition time is controlled within 0.5h.

[0237] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 0.6h, the particle size of the uranium oxalate precipitate crystals generated by the reaction is not greater than 100μm, and the density of the uranium oxalate precipitate crystals is 1-2kg / L.

[0238] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated uranium oxalate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 9%, indicating that the equipment performance met the requirements.

[0239] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0240] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0241] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0242] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0243] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0244] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0245] Example 13

[0246] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 4 in that:

[0247] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution based on the mass of plutonium is 40 g / L, the concentration of the real material oxalic acid solution is 0.2 mol / L, the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 2.5 mol / L.

[0248] The aging time of the real material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, is 1.7h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 60μm, and the density of the plutonium oxalate precipitate crystals is 2-3kg / L.

[0249] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be uranyl nitrate solution and simulated oxalic acid solution respectively.

[0250] Initial debugging stage of equipment:

[0251] The simulated liquid used uranyl nitrate solution with a uranyl ion concentration of 40 g / L; the simulated oxalic acid solution with a concentration of 0.6 mol / L was used, and no additional nitric acid was added to the system. The molar ratio of simulated oxalic acid to uranyl nitrate was 1.3:1.

[0252] Test method: Add uranyl nitrate solution into the reactor, then add oxalic acid solution quantitatively, and the oxalic acid addition time is controlled within 0.4h.

[0253] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 1.7 hours. The particle size of the uranyl oxalate precipitate crystals generated by the reaction is not greater than 60 μm, and the density of the uranyl oxalate precipitate crystals is 2 to 3 kg / L.

[0254] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated uranyl oxalate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 7%, indicating that the equipment performance met the requirements.

[0255] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0256] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0257] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0258] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0259] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0260] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0261] Embodiment 14

[0262] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 4 in that:

[0263] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution is 100 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.8 mol / L, the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 4 mol / L.

[0264] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, is aged for 1 hour. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is not greater than 100μm, and the density of the plutonium oxalate precipitate crystals is 1.5-2.5kg / L.

[0265] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be uranyl nitrate solution and simulated oxalic acid solution respectively.

[0266] Initial debugging stage of equipment:

[0267] The simulated liquid used uranyl nitrate solution with a uranyl ion concentration of 100 g / L; the simulated oxalic acid solution with a concentration of 0.8 mol / L was used, and no additional nitric acid was added to the system. The molar ratio of simulated oxalic acid to uranyl nitrate was 1.05:1.

[0268] Test method: Add uranyl nitrate solution into the reactor, then add oxalic acid solution quantitatively, and the oxalic acid addition time is controlled within 0.6h.

[0269] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 1 hour, the particle size of the uranyl oxalate precipitate crystals generated by the reaction is not greater than 100 μm, and the density of the uranyl oxalate precipitate crystals is 1.5-2.5 kg / L.

[0270] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated uranyl oxalate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 9%, indicating that the equipment performance met the requirements.

[0271] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0272] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0273] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0274] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0275] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0276] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0277] Embodiment 15

[0278] This embodiment provides a test method for determining a simulated liquid for a plutonium tail precipitation reaction, which differs from the method in embodiment 4 in that:

[0279] In a batch precipitation reactor, the concentration of the real material plutonium nitrate solution based on the mass of plutonium is 30 g / L, the concentration of the real material oxalic acid solution is 0.6 mol / L, the real material plutonium nitrate solution and the oxalic acid solution react in a nitric acid system, and the initial nitric acid concentration in the nitric acid system is 2.5 mol / L.

[0280] The actual material of the plutonium tail precipitation reaction in the reprocessing plant, the mixed reaction of plutonium nitrate solution and oxalic acid solution, has an aging time of 0.5h. The particle size of the plutonium oxalate precipitate crystals generated by the reaction is no more than 70μm, and the density of the plutonium oxalate precipitate crystals is 1-2.5kg / L.

[0281] According to the similarity of the precipitation reaction of the real material plutonium tail precipitation reaction in the reprocessing plant, which is the mixed reaction of plutonium nitrate solution and oxalic acid solution to produce plutonium oxalate precipitate, the simulated feed solutions are determined to be uranyl nitrate solution and simulated oxalic acid solution respectively.

[0282] Initial debugging stage of equipment:

[0283] The simulated liquid used was a uranyl nitrate solution with a uranyl ion concentration of 30 g / L; the simulated oxalic acid solution concentration was 0.6 mol / L, and the initial nitric acid concentration in the system was 1 mol / L. The molar ratio of the simulated oxalic acid and uranyl nitrate was 1.2:1.

[0284] Test method: Add uranyl nitrate solution into the reactor, then add oxalic acid solution quantitatively, and the oxalic acid addition time is controlled within 40 minutes.

[0285] The aging time of the mixed reaction of the plutonium simulated element solution and the simulated oxalic acid solution is 0.5h, the particle size of the uranyl oxalate precipitate crystals generated by the reaction is not greater than 70μm, and the density of the uranyl oxalate precipitate crystals is 1-2.5kg / L.

[0286] The crystal size distribution, crystal particle size, and precipitation reaction conversion rate of the generated uranyl oxalate were analyzed. The actual analysis results were compared with the small experimental data of the precipitation reaction of real materials. The deviation was within 9%, indicating that the equipment performance met the requirements.

[0287] This embodiment also provides a simulated feed solution for a plutonium tail precipitation reaction, which is determined by the method described above.

[0288] The beneficial effects of the simulated feed solution of the plutonium tail precipitation reaction and the determination method thereof in this embodiment are as follows:

[0289] (1) A test method for determining the simulated liquid for the plutonium tail precipitation reaction was developed. The method has good simulation and operability and can be applied to the development, testing, verification or preliminary commissioning of precipitation reactors.

[0290] (2) Several simulated liquid compositions and preparation methods are given, which have good simulation performance, easy to obtain raw materials, and are convenient for use in different working conditions and research stages;

[0291] (3) A test method for simulating the feed liquid of the plutonium tail precipitation reactor is provided, which can be used as a reference for the development, research, acceptance and commissioning of other plutonium-containing equipment.

[0292] (4) An experimental method for determining the simulated liquid for the plutonium tail precipitation reaction is proposed. The method has good simulation and strong operability. The composition ratio of the simulated liquid is given, and a suitable experimental research method is given according to the working characteristics of the precipitation reactor. The method is reasonable, efficient and highly operational.

[0293] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A test method for determining a simulated liquid for a plutonium tail precipitation reaction, characterized in that: The following steps are involved: According to the similarity of the precipitation reaction of the real material plutonium tail-end precipitation reaction in the reprocessing plant, which is the mixture reaction of plutonium nitrate solution and oxalic acid solution to form plutonium oxalate precipitate, it is determined that the simulated feed liquids are respectively a solution of plutonium simulated element and a simulated oxalic acid solution, and a mixture of a solution of plutonium simulated element and a simulated oxalic acid solution, and the reaction forms an oxalate precipitate of plutonium simulated element.

2. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 1, characterized in that: The simulated element of plutonium is any one of Fe, Ce and U.

3. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 1, characterized in that: The precipitation reaction is a precipitation crystallization reaction. The similarity of the precipitation crystallization reaction refers to any one or more of the similarities of precipitation crystallization rate, aging time, crystal particle size, crystal density, crystal solubility of the product after precipitation crystallization, and properties of the simulated element of plutonium itself.

4. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 1, characterized in that: The concentration of the real material plutonium nitrate solution is 10-100 g / L based on the mass of plutonium, the concentration of the real material oxalic acid solution is 0.2-0.8 mol / L, the real material plutonium nitrate solution reacts with the oxalic acid solution in a nitric acid system, and the concentration of nitric acid in the nitric acid system is 1.5-4 mol / L.

5. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 1, characterized in that: The aging time of the mixed reaction of the actual material plutonium nitrate solution and oxalic acid solution in the plutonium tail precipitation reaction in the reprocessing plant is not more than 3h, the particle size of the plutonium oxalate precipitate crystals generated by the reaction is not more than 100μm, and the density of the plutonium oxalate precipitate crystals is 1-3kg / L.

6. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 5, characterized in that: The aging time of the mixed reaction of the solution of the simulated plutonium element and the simulated oxalic acid solution is not more than 3 hours, the particle size of the oxalate precipitate crystals of the simulated plutonium element generated by the reaction is not more than 100 μm, and the density of the oxalate precipitate crystals of the simulated plutonium element is 1 to 3 kg / L.

7. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 1, characterized in that: The simulated feed solutions are ferrous sulfate solution and simulated oxalic acid solution, and the reaction generates ferrous oxalate precipitate.

8. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 7, characterized in that: The ratio of the amounts of simulated oxalic acid solution and ferrous sulfate solution is (1.3-1.05):

1.

9. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 1, characterized in that: The simulated feed solutions are cerous nitrate solution and simulated oxalic acid solution, and the reaction generates cerous oxalate precipitate.

10. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 9, characterized in that: The simulated feed liquid cerous nitrate solution and the simulated oxalic acid solution react in a simulated nitric acid system, and the nitric acid concentration in the simulated nitric acid system does not exceed 3 mol / L.

11. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 9, characterized in that: The molar ratio of the simulated oxalic acid solution and the cerous nitrate solution is (1.8-1.55):

1.

12. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 1, characterized in that: The simulated feed solutions are respectively a solution containing uranium and a simulated oxalic acid solution.

13. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 12, characterized in that: The uranium-containing solution is a uranium nitrate solution and / or a uranyl nitrate solution. The uranium nitrate solution reacts with a simulated oxalic acid solution to generate a uranyl oxalate precipitate. The uranyl nitrate solution and oxalic acid generate a uranyl oxalate precipitate.

14. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 13, characterized in that: The ratio of the amounts of simulated oxalic acid solution and uranium nitrate solution is (2.15-2.45):

1.

15. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 13, characterized in that: The ratio of the amounts of simulated oxalic acid solution and uranyl nitrate solution is (1.3-1.05):

1.

16. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to claim 13, characterized in that: The simulated liquid uranyl nitrate solution and the simulated oxalic acid solution react in a simulated nitric acid system, and the nitric acid concentration in the simulated nitric acid system does not exceed 1 mol / L.

17. The test method for determining the simulated liquid for the plutonium tail precipitation reaction according to any one of claims 1 to 16, characterized in that: When reacting in a batch precipitation reactor, a batch of plutonium simulation element solution is added to the batch precipitation reactor, and then the simulated oxalic acid solution is added quantitatively. The simulated oxalic acid solution is added for 0.4 to 0.6 hours.

18. A simulated liquid for plutonium tail precipitation reaction, characterized in that: It is determined by the method described in any one of claims 1 to 17 above.