Operation control method of medical isotope production reactor

Abstract

The invention discloses an operation control method of a medical isotope production reactor. According to the method disclosed by the invention, by coupling reaction between uranyl ions and fission products, radiolysis products and corrosion products, the generation of uranium hydrolytic precipitation, corrosion and fission product precipitation is preliminarily controlled on the basis of a fuel solution with specified uranium concentration, pH value, catalyst and content thereof; and the control strategy of the medical isotope production reactor is designed by further integrating the reactor power density, the solution supplement rate, the operation temperature interval and the operation cycle. Therefore, the possibility of complex chemical reaction caused by coupling of uranyl ions with fission products, radiolysis products and corrosion products is reduced, precipitation caused by influence of multiple factors in the operation process of the medical isotope production reactor is effectively inhibited, and the feedback effect on reactor core reactivity caused by precipitation introduction is eliminated. The stability of the medical isotope production reactor in the operation process is guaranteed, and the required nuclide can be rapidly extracted.

Description

Technical Field

[0001] The present application relates to the technical field of isotope production reactors, and in particular to an operation control method of a medical isotope production reactor. Background Art

[0002] Medical Isotope Production Reactors (MIPR) are aqueous homogeneous reactors that usually use uranyl nitrate or uranyl sulfate solutions as fuel to produce medical isotopes.

[0003] The fission products, radiolysis products and corrosion products produced during the operation of MIPR will cause the liquid fuel to react with some of the fission products, thereby changing the form of uranium in the solution. At the same time, the fission products may also react with each other and precipitate out in the form of precipitation. The increase in the radioactivity of the fission products and the solution will also lead to the generation of H2O and NO 3- The components undergo radiation decomposition reactions, forming a variety of radiolysis products such as H2, O2, N2, nitrogen oxides, H2O2, ·OH, etc. The formation of these radiolysis products will lead to the generation of bubbles, and will also change the pH of the fuel solution and the species form of uranium in the solution. Moreover, radiolysis products with strong oxidizing properties such as ·OH will also accelerate the corrosion of the reactor vessel.

[0004] In related technologies, the hydrolysis behavior of uranyl ions is used to control the concentration of uranyl ions, the pH value of the solution, the temperature of the solution, or the decomposition of hydrogen peroxide catalyzed by metal ions to avoid the formation of uranium peroxide precipitation. However, during the service of MIPR, the fact that liquid fuel does not produce precipitation is affected by multiple factors such as the concentration of uranyl nitrate, fission products, radiolysis products, corrosion products, solution pH, and operating temperature. However, most of the current research results only isolatedly studied the hydrolysis behavior of uranyl ions or the precipitation reaction between uranyl ions and a certain radiolysis product, and have not fully considered the coupled precipitation effect of the above factors, resulting in insufficient stability of MIPR in practical applications. Summary of the invention

[0005] In view of this, the present application provides an operation control method for a medical isotope production reactor, which can effectively suppress precipitation caused by multiple factors during the operation of the isotope production reactor.

[0006] According to one aspect of the present application, there is provided an operation control method for a medical isotope production reactor, comprising:

[0007] The operation of a medical isotope production reactor is controlled according to target operating parameters to suppress the generation of precipitates in a fuel solution of the medical isotope production reactor, wherein the fuel solution is prepared according to target fuel parameters, and the target operating parameters include at least one of reactor power density, solution replenishment rate, operating temperature range and operating cycle.

[0008] Optionally, the target operating parameter includes an operating cycle, and controlling the operation of the medical isotope production reactor according to the target operating parameter includes:

[0009] Determine the first preset duration and the second preset duration in the current operation cycle according to the difference between the content of the target metal ion related to the corrosion reaction in the fuel solution in the previous operation cycle and the content threshold of the target metal ion, wherein the target metal ion includes chromium ion and / or ruthenium ion, the content threshold of the chromium ion is 0.04g / L to 0.06g / L, and the content threshold of the ruthenium ion is 0.015g / L to 0.03g / L;

[0010] In response to the isotope production reactor operating for the first preset time, performing nuclide extraction processing on the fuel solution so that the content of the chromium ions is lower than the chromium ion content threshold;

[0011] In response to the isotope production reactor being in an operating state, accumulating operating hours;

[0012] If the working time is greater than or equal to the second preset time, controlling the purification device to purify the fuel solution so that the content of the ruthenium ions is lower than the content threshold of the ruthenium ions;

[0013] Wherein, the purification rate of the purified metal impurity ions is ≥70%.

[0014] Optionally, the target operating parameters include reactor power density, a preset start-up temperature and an operating temperature range, and controlling the operation of the medical isotope production reactor according to the target operating parameters includes:

[0015] Controlling the start-up of the medical isotope production reactor;

[0016] According to at least one startup power corresponding to the power density, the power of the medical isotope production reactor is controlled to increase in a step-by-step manner until a preset stable power is reached;

[0017] In response to the medical isotope production reactor being in an operating state, a temperature control device of the medical isotope production reactor is controlled to heat or cool the fuel solution according to the operating temperature range corresponding to the start-up power.

[0018] Optionally, the preset stable power is 200kW to 2000kW, the power density is less than 1.8kW / L, and the operating temperature range is 20°C to 90°C.

[0019] Optionally, the startup power and the lower limit of the operating temperature range are positively correlated.

[0020] Optionally, the target fuel parameter includes a solution replenishment rate, and controlling the operation of the medical isotope production reactor according to the target operating parameter includes:

[0021] detecting the pH value of the fuel solution according to a preset adjustment cycle;

[0022] If the pH value of the fuel solution exceeds a preset pH value range, adding an acidic solution and water to the fuel solution according to different solution replenishment rates;

[0023] Wherein, the acidic solution includes nitric acid solution or sulfuric acid solution.

[0024] Optionally, the concentration of the acidic solution is 7 mol / L to 14 mol / L, and the replenishment rate of the acidic solution is 4×10 -3 L / (kW·h)~8.2×10 -3 L / (kW·h);

[0025] The water replenishment rate is less than or equal to 2.8×10 -3 L / (kW·h).

[0026] Optionally, the target fuel parameter includes at least one of a pH value, a uranium concentration, a catalyst, and a content of the catalyst in the fuel solution.

[0027] Optionally, the pH value of the fuel solution is in the range of 0 to 2.8;

[0028] The uranium concentration is less than or equal to 400 gU / L.

[0029] Optionally, the catalyst comprises nitrate, wherein the nitrate comprises at least one of iron, manganese, nickel, copper and silver;

[0030] The content of the catalyst in the fuel solution is 0.5 g / L to 3.5 g / L.

[0031] Through the above technical scheme, by coupling the reaction between uranyl ions and fission products, radiolysis products, and corrosion products, the generation of uranium hydrolysis precipitation and corrosion, and fission product precipitation is preliminarily controlled based on the fuel solution with specified uranium concentration, pH value, catalyst and its content, and the control strategy of the isotope production reactor is further designed by integrating the reactor power density, solution replenishment rate, operating temperature range and operating cycle. This reduces the possibility of complex chemical reactions between uranyl ions and fission products, radiolysis products, and corrosion products, and effectively inhibits the precipitation caused by multiple factors during the operation of the isotope production reactor, eliminates the feedback effect of precipitation on the core reactivity, ensures the stability of the isotope production reactor during operation, and helps to quickly extract the required nuclides.

[0032] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0034] Figure 1 A schematic flow chart of an operation control method of an isotope production reactor provided in an embodiment of the present application is shown;

[0035] Figure 2 A schematic diagram showing the relationship between the species form of uranium and the pH value and the concentration of hydrogen peroxide when the uranyl ion concentration provided in the embodiment of the present application is 0.63 mol / L;

[0036] Figure 3 A schematic diagram showing the relationship between the species form of uranium and the pH value and the concentration of hydrogen peroxide when the uranyl ion concentration provided in the embodiment of the present application is 1.0 mol / L;

[0037] Figure 4 A schematic diagram showing the relationship between the species form of uranium and the pH value and the concentration of hydrogen peroxide when the uranyl ion concentration provided in the embodiment of the present application is 1.2 mol / L;

[0038] Figure 5 A schematic diagram showing the relationship between the species form of uranium and the pH value and the concentration of hydrogen peroxide when the uranyl ion concentration provided in the embodiment of the present application is 1.5 mol / L;

[0039] Figure 6A schematic diagram showing the relationship between the species form of uranium and the pH value and the hydrogen peroxide concentration when the uranyl ion concentration provided in the embodiment of the present application is 2.0 mol / L. DETAILED DESCRIPTION

[0040] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0041] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0042] Those skilled in the art will appreciate that, unless expressly stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, or there may be intermediate elements. In addition, the "connection" or "connection" used herein may include wireless connection or wireless fusion. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0043] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments set forth herein. It should be understood that these embodiments are provided to make the disclosure of the present application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art.

[0044] An isotope production reactor is a nuclear reactor specifically used to produce radioactive isotopes. It can mass-produce a variety of radioactive isotopes required in the medical, industrial and scientific research fields. Taking the medical isotope production reactor as an example, the medical isotope production reactor produces radioactive nuclides such as molybdenum-99, iodine-131, and strontium-89 through fission reactions using uranyl nitrate or uranyl sulfate solutions as fuel solutions. The uranium in the solution is both the "fuel" for the nuclear reaction and the "target material" for producing radioactive isotopes.

[0045] In this embodiment, an operation control method of an isotope production reactor is provided, such as Figure 1 As shown, the method includes:

[0046] Step 110, controlling the operation of the isotope production reactor according to the target operating parameters to suppress the generation of precipitates in the fuel solution of the isotope production reactor.

[0047] The target operating parameters include at least one of reactor power density, solution replenishment rate, operating temperature range and operating cycle.

[0048] Further, the fuel solution is prepared according to the target fuel parameters. The target fuel parameters include at least one of pH value, uranium concentration, catalyst and the content of catalyst in the fuel solution. Generally, the uranium concentration is less than or equal to 400 gU / L. Usually, the uranium concentration is controlled within the range of 200 gU / L to 300 gU / L, within which the higher the uranium concentration, the better.

[0049] The operation control method of the isotope production reactor provided in the embodiment of the present application preliminarily controls the generation of uranium hydrolysis precipitation and corrosion, and fission product precipitation based on a fuel solution with a specified uranium concentration, pH value, catalyst and its content by coupling the reaction between uranyl ions and fission products, radiolysis products, and corrosion products, and further designs the control strategy of the isotope production reactor by comprehensively considering the reactor power density, solution replenishment rate, operating temperature range, and operating cycle. This reduces the possibility of complex chemical reactions occurring due to coupling between uranyl ions and fission products, radiolysis products, and corrosion products, and effectively inhibits precipitation caused by multiple factors during the operation of the isotope production reactor, eliminates the feedback effect of precipitation on the core reactivity, ensures the stability of the isotope production reactor during operation, and helps to quickly extract nuclides.

[0050] It should be noted that, depending on the type, conditions and mechanism of precipitate formation under reactor operating conditions, the following reactions may occur in the fuel solution.

[0051] (a) For the hydrolysis reaction of uranyl ions.

[0052] During the irradiation process in the reactor, the acid radical ions undergo decomposition reactions with fission products, neutrons, and gamma rays, resulting in the loss of nitrate radicals, which will cause the pH to rise, that is, the acidity of the fuel solution decreases. When the acidity of the fuel solution decreases, the uranyl ions (UO2 2+ ) is hydrolyzed to form UO2(OH) + , as the pH value increases, UO2(OH) + A reaction occurs to form UO3·H2O precipitate.

[0053] The decomposition reaction equation is as follows:

[0054]

[0055] The hydrolysis reaction equation is as follows:

[0056]

[0057] (ii) For radiation decomposition related reactions, such as H2O and NO3 - Radiation decomposition of components and reactions initiated by radiation products.

[0058] Under the action of radiation particles, water molecules are excited and ionized to form hydrogen free radicals ·H and hydroxyl free radicals ·OH. ·H and ·OH combine to form H2O, H2, and H2O2 (hydrogen peroxide). The H2O2 produced by water irradiation can react with UO2 2+ A chemical reaction occurs to form uranium ore (UO2(O2)·2H2O) precipitate.

[0059] The radiolysis reaction equation is as follows:

[0060] 3H2O→·H+·OH+H2+H2O2;

[0061] H2O2 and UO2(NO3)2 react to form UO2(O2)·2H2O. The relevant chemical reaction formula is as follows:

[0062]

[0063] Considering the effects of thermal decomposition and catalyst, the calculation formula for the yield of hydrogen peroxide in the pile is as follows:

[0064] d(H2O2) / dt=λ×G×W×σ;

[0065] In the formula, λ is a constant for unit conversion, which can be set according to the time accuracy, for example, λ = 0.0062; G is the number of hydrogen peroxide molecules produced for every 100ev absorbed molecules; W is the reactor power density (unit kW / L), which refers to the amount of energy released per unit volume. The higher the reactor power density, the greater the heat generated and the higher the overall temperature of the reactor; σ is the coupling reaction coefficient. For a uniform reactor in operation, about 96% of the hydrogen produced in the solution comes from fission recoil particles, 2% from neutrons, and 2% from gamma rays. The latter two items are usually ignored. Since the part caused by recoil is usually above 0.96, part of the energy of prompt neutrons, gamma rays and radioactive decay escapes from the solution, so σ can be set to 0.96.

[0066] According to the amount of irradiation decomposition, HNO3 is emitted by radiolysis, and water continues to return to the reactor through the gas recombination system with a recombination rate of not less than 95%.

[0067] (III) For corrosion and fission product related reactions, such as reactions between fission products and reactions between fission products and UO2 2+ reaction.

[0068] In the fuel solution, fission products refer to various nuclides produced during the fission of uranium isotopes such as uranium-235 or uranium-233. Fission products consume acid radicals to form metal ions, such as Fe 3+ 、TcO4 - and MoO4 2- Under certain conditions, free metal ions react with other fission products and corrosion products to form metal salt precipitates with low solubility, such as molybdate precipitates. At the same time, some of the corroded Fe, Cr, and Ni will dissolve in the solution in the form of ions, among which Cr ions (Cr 3 + ) will accelerate the intergranular corrosion of 304L stainless steel. The corrosion rate of the container is related to the pH value of the solution. The lower the pH value, the faster the corrosion rate.

[0069] The reactions between coupled uranyl ions and fission products, corrosion products, and radiolysis products show that keeping the fuel solution at a low pH value during the configuration of the fuel solution and the operation of the isotope production reactor can increase the H + concentration, thereby effectively inhibiting uranium hydrolysis and precipitation. At the same time, in order to alleviate the corrosion of the container, the pH value should not be too low. Furthermore, the yield of hydrogen peroxide in the reactor is directly related to the reactor power density and the catalyst. Moreover, due to the instability of hydrogen peroxide, heating will cause it to decompose. The lower the reactor power density, the less hydrogen peroxide is produced. High temperature and catalysts can accelerate the decomposition of H2O2. By controlling the reactor power density, solution temperature and catalyst, the content of H2O2 in the solution can be reduced, thereby reducing the reaction of H2O2 and UO2(NO3)2 and UO4 saturation, thereby achieving control and elimination of precipitation. At the same time, it is stipulated that the reactor should be purified in time during the actual operation time to reduce the metal content in the solution, so as to avoid fission, precipitation of corrosion products and accelerated corrosion.

[0070] In one embodiment, when the uranium concentration is less than or equal to 400 gU / L, the pH value can be controlled within the range of 0 to 2.8 to take into account the effects of corrosion products and radiolysis products on the fuel solution.

[0071] For example, taking the fuel solution as uranyl nitrate (UO2(NO3)2), uranyl nitrate is a strong acid and weak base salt, and its solution is acidic. The pH value of the mixed system solution of uranyl nitrate and nitric acid is less than the pH value corresponding to the concentration of nitric acid. When the core capacity of the isotope reactor is 100L to 200L and the concentration of uranyl nitrate is 230g / L, the pH value of uranyl nitrate can be reduced by adding additional nitric acid solution, thereby controlling the fuel solution from hydrolysis and precipitation.

[0072] In one embodiment, the target fuel parameters include a solution replenishment rate, and the operation of the isotope production reactor is controlled according to the target operating parameters, including: detecting the pH value of the fuel solution according to a preset adjustment cycle; if the pH value of the fuel solution exceeds a preset pH value range, adding an acidic solution and water to the fuel solution according to different solution replenishment rates.

[0073] Among them, the relationship between UO4 and pH value and H2O2 obtained by thermodynamic calculation, as well as the relationship between uranium species and pH value and H2O2 concentration under different uranyl ion concentrations. Figures 2 to 6 As shown in the figure, when the pH is less than 2.8, if the solution system does not produce uranium peroxide precipitation, the concentration of H2O2 needs to be controlled not to exceed the concentration limit of H2O2 at the corresponding pH value, so that uranium peroxide precipitation will not be produced in the solution. As the initial uranyl nitrate concentration increases, the change trend of the solution species in the reaction system is basically the same. Figure 4 , Figure 5 , Figure 6 Shown in UO2 2+ When the concentration exceeds 1.2 mol / L, some UO2 2+ The species area will become soluble [(UO2)2(OH)] 3+ , with UO2 2+ The increase in concentration, [(UO2)2(OH)] 3+ The species formation zone will gradually become larger, while the precipitation species formation zone will increase very slightly. The formation of uranium species in the reaction system can be ignored with the change of uranium concentration. Therefore, during the operation of the isotope production reactor, the uranyl ion concentration does not exceed the solubility, and the H2O2 concentration is reduced as much as possible, and the operating pH value is reasonably controlled to avoid UO4 saturation and precipitation.

[0074] Specifically, the preset pH value range is 0 to 2.8. For example, the pH value may be 0.5, 1, 1.5, 1.76, 2.4, etc.

[0075] In this embodiment, the pH value of the fuel solution is periodically detected. If the pH value does not meet the preset pH value range where no hydrolysis precipitation occurs, an acidic solution and water are added to the fuel solution in a timely manner to inhibit the radiolysis reaction of water and acid, thereby ensuring that the reactor is in a state where no precipitation occurs.

[0076] Furthermore, taking into account the different decomposition amounts and reaction rates of the radiolysis reaction and the hydrolysis reaction, an acid solution and water are added to the fuel solution at different non-replenishing rates to maintain a balance between the acid and water, so that the uranium concentration in the fuel solution can ensure the normal operation of the reactor without precipitation.

[0077] It is understandable that the replenishment rate of acidic solutions of different concentrations is different. The higher the concentration of the acidic solution, the stronger its ability to adjust pH. In order to maintain the balance between the radiolysis reaction and the hydrolysis reaction, the replenishment rate of the acidic solution should be lower. When the solute of the fuel solution is uranyl nitrate, the acidic solution is nitric acid; when the solute of the fuel solution is uranyl sulfate, the acidic solution is sulfuric acid.

[0078] In one embodiment, the concentration of the acidic solution is 7 mol / L to 14 mol / L, and the replenishment rate of the acidic solution is 4×10 -3 L / (kW·h)~8.2×10 -3 L / (kW·h); water replenishment rate is less than or equal to 2.8×10 -3 L / (kW·h).

[0079] For example, to maintain the balance of HNO3 and water in the fuel solution, the acid solution and water are added to the fuel solution according to different solution replenishment rates. For nitric acid with a concentration of 7.61 mol / L, the maximum acid replenishment rate is: the acid replenishment frequency shall not exceed 1h, and the acid replenishment amount is 8×10 -3 L / kW, which is a rate of 8×10 -3 L / (kW·h); The minimum acid replenishment rate is: the acid replenishment frequency shall not exceed 1h, and the acid replenishment amount is 7.76×10 -3 L / kW, which is a rate of 7.76×10 -3 L / (kW·h); for nitric acid with a concentration of 13.47 mol / L, the maximum acid replenishment rate is: the acid replenishment frequency shall not exceed 1h, and the acid replenishment amount is 4.49×10 -3 L / kW, which is a rate of 4.49×10 -3 L / (kW·h); The minimum acid replenishment rate is: the acid replenishment frequency shall not exceed 1h, and the acid replenishment amount is 4.4×10 -3 L / kW, which is a rate of 4×10 -3 L / (kW·h). At the same time, the water replenishment frequency should not be greater than 1h, and 2.32×10 -3 L / kW, the rate is 2.32×10 -3 L / (kW·h). It is understandable that the designed acid replenishment system has the ability to adjust the acidity and the frequency of acid replenishment can be adjusted according to demand.

[0080] In one embodiment, when preparing the solution, a proper amount of catalyst is added to the fuel solution and mixed with the fuel solution. After the reactor is started, under the action of temperature and catalyst, the catalyst reacts with H2O2 produced by radiolysis to catalyze the decomposition of H2O2, so as to reduce the content of H2O2 in the solution, thereby reducing the reaction of H2O2 and UO2(NO3)2 and UO4 saturation, thereby achieving control and elimination of precipitation.

[0081] The decomposition reaction of H2O2 is as follows:

[0082] H2O2→0.5O2+H2O;

[0083] H2O2=(λ×G×W×σ) / (k+k cat (Cat));

[0084] Where k is the molar rate constant in the absence of catalyst; k cat is the catalytic constant; Cat is the catalyst concentration in mol / l.

[0085] Exemplarily, the catalyst includes nitrate. When the solute of the fuel solution is uranyl nitrate, the catalyst for decomposing hydrogen peroxide is a nitrate catalyst with a content in the fuel solution greater than or equal to 0.5 g / L and less than or equal to 3.5 g / L. This promotes the thermal decomposition reaction of H2O2. In this way, even if the reactor is operated at 70°C and greater than 800 kW, no precipitation occurs.

[0086] Furthermore, some cations of fission products and corrosion products such as Fe 3+ 、Ag + 、Ni 2+ , Cu 2+ etc. can catalyze the thermal decomposition reaction of H2O2. Copper salts and nickel salts etc. have a significant catalytic effect on the radiolysis of other hydrogen into water and the decomposition of hydrogen peroxide into water. Therefore, a nitrate containing at least one of iron, manganese, nickel, copper and silver can be selected as a catalyst. For example, the nitrate can be at least one of iron nitrate, manganese nitrate, nickel nitrate, silver nitrate and copper nitrate.

[0087] In one embodiment, when the target operating parameters include reactor power density and operating temperature range, step 110, i.e., controlling the operation of the isotope production reactor according to the target operating parameters, includes: controlling the isotope production reactor to start up; controlling the power of the isotope production reactor to increase in a step-by-step manner according to at least one start-up power corresponding to the reactor power density until a preset stable power is reached; in response to the isotope production reactor being in an operating state, controlling the temperature control device of the isotope production reactor to heat or cool the fuel solution according to the operating temperature range corresponding to the start-up power.

[0088] The preset stable power is 200kW to 2000kW, for example, 500kW, 800kW, etc., which can be set according to the volume of the fuel solution. The operating temperature range is 20℃ to 90℃.

[0089] In this embodiment, the power of the isotope production reactor is increased stepwise according to at least one starting power corresponding to the reactor power density, until the preset stable power is reached, then the power increase is stopped and the stable power operation is maintained. Thus, the isotope production reactor is gradually adjusted to a condition suitable for isotope production, which can not only reduce the thermal shock of the reactor internal structure caused by the rapid temperature change, thereby extending the service life of the reactor, but also can better adjust the productivity of isotopes by precisely controlling the power increase process by increasing the power in stages, ensuring that the production capacity at different stages reaches the optimal state.

[0090] Furthermore, when the isotope production reactor is in operation, the temperature control device of the isotope production reactor is controlled to adjust the temperature of the fuel solution in real time according to the operating temperature range corresponding to the start-up power. Thus, the fuel solution of the isotope production reactor can be in a stable temperature environment, ensuring the safety and production efficiency of the isotope production reactor. At the same time, a certain temperature can also promote the catalyst to decompose hydrogen peroxide, further reducing the generation of precipitation.

[0091] In one embodiment, step 110, controlling the operation of the isotope production reactor according to the target operating parameters, includes: controlling the power density of the isotope production reactor to be less than 1.8 kW / L, which may be 0.8 kW / L, 1.4 kW / L, 1.6 kW / L, etc.

[0092] In this embodiment, when the isotope production reactor is operated at a power density of less than 1.8 kW / L, the heat generated is low, which reduces the thermal effect of the radiolysis reaction and reduces the amount of hydrogen peroxide produced. At the same time, the heat generated by the isotope production reactor can heat the fuel solution, and the higher temperature helps promote the catalyst to decompose hydrogen peroxide, the catalytic efficiency will be higher, and the precipitation control effect will be better.

[0093] In actual application scenarios, the startup power and the lower limit of the operating temperature range are positively correlated. In this way, at lower power levels, maintaining the required minimum temperature can reduce the coolant flow requirements, which not only reduces the power demand of the pump, but also reduces the complexity of the system. And at higher power levels, higher operating temperatures can improve the thermal efficiency of the heat exchange system, allowing the reactor to produce more energy at lower fuel consumption. This allows the isotope production reactor to maintain stable operation at different power levels, reducing reactor instability caused by temperature fluctuations, thereby improving the overall reliability of the system.

[0094] For example, the Fe(NO3)3 content of the catalyst is 3 g / L, the core capacity is 120L-160L, the reactor power density is 1.58 kW / L, and the corresponding relationship between the start-up power and the operating temperature range is shown in Table 1.

[0095] Table 1

[0096] Start-up power / kW 0 10 40 150 200 300 400 800 2000 Temperature lower limit / ℃ Freezing point 30 50 60 62 65 67 70 72 Temperature upper limit / ℃ 90 90 90 90 90 90 90 90 90

[0097] Among them, the freezing point of the fuel solution is about 0°C.

[0098] In one embodiment, the target operating parameters include an operating cycle, and the operating cycle includes: a first preset duration for triggering a nuclide extraction process during the operation of the isotope production stack, and a second preset duration for triggering a purification process; step 110, i.e., controlling the operation of the isotope production stack according to the target operating parameters, includes: determining a first preset duration and a second preset duration in the current operating cycle according to a difference between a content of target metal ions related to corrosion reactions in the fuel solution in a previous operating cycle and a threshold value of a content of the target metal ions; performing a nuclide extraction process on the fuel solution in response to the first preset duration of the operation of the isotope production stack; accumulating the operating time in response to the isotope production stack being in operation; and controlling the purification device to perform a purification process on the fuel solution if the operating time is greater than or equal to the second preset time.

[0099] Among them, the target metal ions include chromium ions and / or ruthenium ions, the chromium ion content threshold is 0.04g / L~0.06g / L, and the ruthenium ion content threshold is 0.015g / L~0.03g / L. The purification treatment includes centrifugation, filtration, ion exchange, etc. The second preset time is used to trigger the purification treatment, which can be reasonably set according to the isotope production pile capacity, element concentration, etc. Exemplarily, the second preset time can be set to no more than half a year, such as 1 month, 3 months, half a year, etc., and the embodiments of this application will not be listed one by one.

[0100] In this embodiment, the isotope production reactor stops working for a first preset time and performs nuclide extraction. When passing through the Al2O3 extraction column, the chromium ions in the solution will be absorbed, so that the chromium ion content of the fuel solution in the production reactor is lower than the corresponding content threshold. Similarly, after the cumulative work of the isotope production reactor reaches the second preset time, the control system will start the purification device, and the fuel solution will be purified by the purification device to filter out unnecessary impurities such as excess ruthenium ions and reduce the content of some metals in the solution. In this way, the reactor periodically performs necessary cooling, sampling and maintenance to avoid intergranular corrosion of stainless steel containers, reduce the impact of long-term operation on equipment and isotope quality, further reduce the precipitation of fission and corrosion products, and ensure the safety and production efficiency of the isotope production reactor.

[0101] For example, experiments show that Cr 3+In the presence of H2O2, Cr 6+ The fuel solution is extracted once every two days and all of it will be absorbed when it passes through the Al2O3 extraction column. 6+ Meet the requirement that the content is below 0.05g / L to avoid Cr 6+ The Ru ions produced by irradiation are controlled below 0.02 g / L through purification every six months.

[0102] It should be noted that the aforementioned multiple target operating parameters for controlling sedimentation can be used alone or in combination to achieve the synergistic effect of different control strategies. Specific embodiment:

[0104] A 230gU / L uranyl nitrate fuel solution was used, and an additional 0.2mol / L nitric acid was added to reduce the pH value of the uranyl nitrate fuel solution to 1.76. During operation, the reactor power was 300kW when operating at full power, and the volume during operation was between 120L and 160L. The reactor power density was 1.25kW / L to 1.67kW / L. During the start-up process, different start-up power steps were set. The reactor was first electrically heated until the temperature reached the lower limit of Table 1 before the power was increased. The power and density after stable operation must be within the range allowed by Table 1. The reactor was operated for two days and stopped for one day for isotope extraction. During the operation of the reactor, acid was continuously replenished, and the acid replenishment frequency should not be greater than 1h. The nitric acid concentration was 13.47mol / L, and the acid replenishment amount was 4.4×10 -3 L / kW, and 2.32×10 -3 L / kW. Take samples every day to test the pH value of the fuel solution to ensure that the pH value of the fuel solution is 0<pH<2.3, which can avoid the precipitation of UO3﹒2H2O. When the uranium concentration (uranyl ion concentration) is 230gU / L, if Figure 3 As shown, the concentration of hydrogen peroxide is controlled to be less than 10 - 6 mol / L, by adding 3mg / L Fe(NO3)3, the fuel solution is controlled to operate within the temperature and power range allowed in Table 1, and the isotope extraction is performed for two days of operation and one day of shutdown, using an Al2O3 extraction column. Purification is performed once every six months, with a purification rate of ≥70%. This ensures that the uranyl nitrate fuel solution does not precipitate.

[0105] Comparative Example:

[0106] A 230gU / L uranyl nitrate fuel solution was used, and an additional 0.2mol / L nitric acid was added to reduce the pH value of the uranyl nitrate fuel solution to 1.76. During operation, the reactor power was 300kW when operating at full power, and the volume during operation was between 120L and 160L. The reactor power density was 1.25kW / L to 1.67kW / L. During the start-up process, different start-up power steps were set. The reactor was first electrically heated until the temperature reached the lower limit of Table 1 before the power was increased. The power and density after stable operation must be within the range allowed by Table 1. The reactor was operated for two days and stopped for one day for isotope extraction. During the operation of the reactor, acid was continuously replenished, and the acid replenishment frequency should not be greater than 1h. The nitric acid concentration was 13.47mol / L, and the acid replenishment amount was 2×10 -3 L / kW, and 2.32×10 - 3 The pH value of the fuel solution was tested daily and it was found that the pH value increased to more than 4 and precipitation occurred.

[0107] It should be noted that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0108] Those skilled in the art will appreciate that the accompanying drawings are only schematic diagrams of a preferred implementation scenario, and the modules or processes in the accompanying drawings are not necessarily necessary for implementing the present application. Those skilled in the art will appreciate that the modules in the devices in the implementation scenario can be distributed in the devices of the implementation scenario according to the description of the implementation scenario, or can be changed accordingly and located in one or more devices different from the present implementation scenario. The modules of the above-mentioned implementation scenario can be combined into one module, or can be further split into multiple submodules.

[0109] The above serial numbers of this application are only for description and do not represent the advantages and disadvantages of the implementation scenarios. The above disclosure is only a few specific implementation scenarios of this application, but this application is not limited to them, and any changes that can be thought of by technicians in this field should fall within the scope of protection of this application.

Claims

1. A method for controlling the operation of a medical isotope production reactor, characterized in that: The method comprises: The operation of a medical isotope production stack is controlled according to target operating parameters to suppress the generation of precipitates in a fuel solution of the medical isotope production stack, wherein the fuel solution is prepared according to target fuel parameters, and the target operating parameters include at least one of power density, solution replenishment rate, operating temperature range and operating cycle.

2. The operation control method of the medical isotope production reactor according to claim 1, characterized in that: The target operating parameters include an operating cycle, and controlling the operation of the medical isotope production reactor according to the target operating parameters includes: Determine the first preset duration and the second preset duration in the current operation cycle according to the difference between the content of the target metal ion related to the corrosion reaction in the fuel solution in the previous operation cycle and the content threshold of the target metal ion, wherein the target metal ion includes chromium ion and / or ruthenium ion, the content threshold of the chromium ion is 0.04g / L to 0.06g / L, and the content threshold of the ruthenium ion is 0.015g / L to 0.03g / L; In response to the isotope production reactor operating for the first preset time, performing nuclide extraction processing on the fuel solution so that the content of the chromium ions is lower than the chromium ion content threshold; In response to the isotope production reactor being in an operating state, accumulating operating hours; If the working time is greater than or equal to the second preset time, controlling the purification device to purify the fuel solution so that the content of the ruthenium ions is lower than the content threshold of the ruthenium ions; Wherein, the purification rate of the purified metal impurity ions is ≥70%.

3. The operation control method of the medical isotope production reactor according to claim 1, characterized in that: The target operating parameters include reactor power density and operating temperature range, and controlling the operation of the medical isotope production reactor according to the target operating parameters includes: Controlling the start-up of the medical isotope production reactor; According to at least one startup power corresponding to the power density, the power of the medical isotope production reactor is controlled to increase in a step-by-step manner until a preset stable power is reached; In response to the medical isotope production reactor being in an operating state, a temperature control device of the medical isotope production reactor is controlled to heat or cool the fuel solution according to the operating temperature range corresponding to the start-up power.

4. The operation control method of the medical isotope production reactor according to claim 3, characterized in that: The preset stable power is 200kW to 2000kW; The power density is less than 1.8 kW / L; The operating temperature range is 20°C to 90°C.

5. The operation control method of the medical isotope production reactor according to claim 3, characterized in that: The startup power and the lower limit of the operating temperature range are positively correlated.

6. The operation control method of the medical isotope production reactor according to claim 1, characterized in that: The target fuel parameter includes a solution replenishment rate, and the controlling the operation of the medical isotope production reactor according to the target operating parameter includes: detecting the pH value of the fuel solution according to a preset adjustment cycle; If the pH value of the fuel solution exceeds a preset pH value range, adding an acidic solution and water to the fuel solution according to different solution replenishment rates; Wherein, the acidic solution includes nitric acid solution or sulfuric acid solution.

7. The operation control method of the medical isotope production reactor according to claim 6, characterized in that: The concentration of the acid solution is 7 mol / L to 14 mol / L, and the replenishment rate of the acid solution is 4×10 -3 L / (kW·h)~8.2×10 -3 L / (kW·h); The water replenishment rate is less than or equal to 2.8×10 -3 L / (kW·h).

8. The operation control method of the medical isotope production reactor according to claim 1, characterized in that: The target fuel parameter includes at least one of a pH value, a uranium concentration, a catalyst, and a content of the catalyst in the fuel solution.

9. The operation control method of the medical isotope production reactor according to claim 8, characterized in that: The pH value of the fuel solution is in the range of 0 to 2.8; The uranium concentration is less than or equal to 400 gU / L.

10. The operation control method of the medical isotope production reactor according to claim 8, characterized in that: The catalyst includes nitrate, wherein the nitrate contains at least one of iron, manganese, nickel, copper and silver; The content of the catalyst in the fuel solution is 0.5 g / L to 3.5 g / L.

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