Control method for activation corrosion product source item of boron-free nuclear reactor

Abstract

The invention provides a control method for a boron-free nuclear reactor activation corrosion product source item. The control method for the activation corrosion product source item of the boron-free nuclear reactor comprises the following steps: during shutdown of the boron-free nuclear reactor, reducing the temperature of a coolant in a primary loop of the boron-free nuclear reactor to a first temperature, and injecting a H2O2 solution into the coolant in the primary loop for oxidation operation; in the oxidation operation, the concentration of H2O2 in the coolant in the primary loop is in a set concentration range; wherein the pH value of the coolant in the primary loop is 9.3 to 9.7, and the set concentration of H2O2 in the coolant in the primary loop is 18 mg / kg to 20 mg / kg. According to the control method, boric acid and other pH regulators are not needed to regulate the pH value of the primary loop coolant, and the subsequent step of removing the pH regulators can be omitted; the method can be applied to the boron-free nuclear reactor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear reactor oxidation operation, in particular to a method for controlling activation corrosion product source of a boron-free nuclear reactor. BACKGROUND

[0002] After the metal pipeline of the primary loop system of the nuclear reactor generates corrosion products, the corrosion products migrate with the coolant flow to eventually deposit on the surface of the fuel core and be activated into activated corrosion products, which are distributed in the fuel core, the coolant, other main system equipment, pipelines and connected system equipment. In nuclear power plants, oxidation purification of the corrosion products in the primary loop of the nuclear reactor is very important.

[0003] Factors affecting the activated corrosion product source include congenital design factors and acquired operation and maintenance factors. The congenital design factors include material composition, equipment processing and manufacturing process, core design, system process parameters, etc. The acquired operation and maintenance factors include chemical control, operation condition, fuel ultrasonic decontamination and start-stop control, etc. At present, most nuclear power plants choose to perform oxidation operation at an appropriate time during the shutdown process to make the activated corrosion products release quickly, and then remove the corrosion products in the loop through the resin bed, so as to effectively control the radiation source and reduce the collective dose of the overhaul.

[0004] Oxidation operation refers to making the activated corrosion products oxidize and then fall off from the surface of the core and the pipeline into the coolant during the later stage of the shutdown process, and then capturing the activated corrosion products through the purification bed and the filter of the chemical volume control system, so as to reduce the radiation level of the equipment and the pipeline and the collective dose of the overhaul personnel.

[0005] Oxidation operation includes natural oxidation operation and forced oxidation operation. The natural oxidation operation is to lift the reactor head cover out of the reactor during shutdown to make the coolant system completely communicate with the atmosphere, at which time the air and the activated corrosion products have a certain weak oxidation reaction to promote the corrosion products to further fall off into the coolant. Since the oxygen content in the air is small and the flow of the main system is limited, the reaction of the natural oxidation operation is extremely slow and is not conducive to the complete oxidation of ferrous ions into ferric ions (green ferrous colloid may be formed to make the refueling pool turbid). In addition, the occurrence time of the activated corrosion product peak of the primary loop coolant is uncertain, which is not conducive to the judgment of the subsequent operation. The forced oxidation operation is to reduce the temperature of the primary loop coolant to about 80°C during the shutdown of the nuclear reactor, and then add a certain amount of oxidizing agent through the control box of the chemical volume control system to have an oxidation reaction. The oxidation reaction of the forced oxidation operation is relatively strong and efficient, the activated corrosion products can quickly fall off from the pipeline and be absorbed by the purification bed and the filter of the chemical volume control system, and the purpose of reducing the radioactivity of the main system can be achieved in a relatively short time, which has been widely used in many nuclear power plants.

[0006] However, the conventional forced oxidation operation method is designed for large-scale boron and lithium containing pressurized water reactor, and there is still a lack of oxidation operation method suitable for boron-free nuclear reactor. SUMMARY

[0007] Therefore, one or more embodiments of the present application provide a control method of activated corrosion product source term suitable for boron-free nuclear reactor and less damaging to nuclear reactor components.

[0008] According to an aspect of an embodiment of the present application, a control method of activated corrosion product source term of a boron-free nuclear reactor is provided, comprising the following steps:

[0009] During shutdown of the boron-free nuclear reactor, the temperature of the primary coolant in the boron-free nuclear reactor is reduced to a first temperature, and H2O2 solution is injected into the primary coolant for oxidation operation;

[0010] During the oxidation operation, the concentration of H2O2 in the primary coolant is within a set concentration range;

[0011] In some embodiments, the pH value of the primary coolant is 9.3-9.7, and the set concentration of H2O2 in the primary coolant is 18 mg / kg-20 mg / kg.

[0012] In some embodiments, during the oxidation operation, the H2O2 solution is injected for more than twice to make the concentration of H2O2 in the primary coolant within the set concentration range.

[0013] In some embodiments, the oxidation operation method further comprises the following steps:

[0014] During the oxidation operation, the concentration of H2O2 in the primary coolant is measured every set time interval;

[0015] If the measured concentration is lower than the set concentration, H2O2 solution is injected to make the concentration of H2O2 in the primary coolant within the set concentration range.

[0016] In some embodiments, the set time interval is 30 min-60 min.

[0017] In some embodiments, the mass fraction of H2O2 in the H2O2 solution is 20%-40%.

[0018] In some embodiments, the step of reducing the temperature of the primary coolant in the boron-free nuclear reactor to the first temperature comprises:

[0019] After the temperature of the coolant in the primary loop of the boron-free nuclear reactor is reduced to the second temperature, the concentration of H2 in the coolant in the primary loop is reduced; and then the temperature of the coolant in the primary loop is reduced from the second temperature to the first temperature.

[0020] In some embodiments, the first temperature is 80-90℃ and / or,

[0021] The second temperature is 170-180℃.

[0022] In some embodiments, the concentration of H2 in the coolant in the primary loop is reduced to less than or equal to 3mg / kg.

[0023] In some embodiments, the concentration of H2 in the coolant in the primary loop is reduced by introducing N2 into the primary loop.

[0024] In some embodiments, the oxidation operation is performed for 4-6h.

[0025] Compared with the conventional technology, the present application has the following beneficial effects:

[0026] The present application uses H2O2 as the oxidizing agent, and controls the concentration of H2O2 in the oxidation operation process within a specific range, so that it can continuously oxidize the activated corrosion products under the condition that the pH value is 9.3-9.7; thereby improving the oxidation effect of the oxidizing agent on the activated corrosion products in the coolant, and further reducing the residual amount of the corrosion products in the primary loop and causing less damage to the nuclear reactor components. The control method of the activated corrosion product source term of the boron-free nuclear reactor of the present application does not need to use a pH adjuster such as boric acid to adjust the pH value of the coolant in the primary loop, and can save the subsequent step of removing the pH adjuster; therefore, the method of the present application can be applied to the boron-free nuclear reactor. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the specific embodiments of the present application, the drawings needed in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art based on these drawings.

[0028] Figure 1 SEM images of different corrosion coupons after the oxidation operation in Example 1 of the present application;

[0029] Figure 2 SEM images of different corrosion coupons after the oxidation operation in Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0030] In order to make the above objectives, features and advantages of the present application more clear and easily understood, the detailed description of the specific embodiments of the present application is made. In the following description, a lot of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many different ways other than the embodiments described herein, and one of ordinary skill in the art can make similar improvements without departing from the spirit of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Various materials, reagents, instruments and equipment used in the present application are commercially available or can be prepared by known methods.

[0032] In the present application, "a plurality of", "a plurality of kinds", "a plurality of times", "a plurality of elements" and the like, unless otherwise specified, refer to more than two or equal to two in number. For example, "one or more" means one or more than two.

[0033] In the present application, "further", "even further", "in particular" and the like are used for the purpose of description, indicating differences in content, but should not be understood as limiting the scope of protection of the present application.

[0034] In the present application, "optionally", "optional" and "optional" mean optional, i.e. selected from "yes" or "no" two parallel schemes. If there are multiple "optional" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "optional" is independent.

[0035] In the present application, the technical features described in an open way include both the closed technical solution consisting of the listed features and the open technical solution containing the listed features.

[0036] In the present application, when referring to a numerical interval (i.e. a numerical range), unless otherwise specified, the optional numerical values are considered to be continuous within the numerical interval, and include both numerical endpoints (i.e. the minimum and maximum values) of the numerical range, and every numerical value between the two numerical endpoints. When a numerical interval refers only to integers within the numerical interval, unless otherwise specified, the two numerical endpoints and every integer between the two numerical endpoints are considered to be directly listed, e.g. t is an integer selected from 1-10 means that t is any one integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, ranges disclosed herein are to be understood to include any and all sub-ranges subsumed therein.

[0037] In the present application, unless otherwise specified, the temperature parameter allows both constant temperature treatment and variation within a certain temperature interval. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuation within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C is allowed.

[0038] With the development of small nuclear reactor technology, it is increasingly widely used in nuclear power plants. Due to the limited space of small nuclear reactors, boron acid is usually not added to the primary coolant, so that the related system of boron regulation (such as boron recovery system and boron water system) can be simplified, thereby saving the space size of small nuclear reactors and reducing the construction cost and operation and maintenance cost of equipment.

[0039] Traditional forced oxidation operation methods are designed for large-scale boron-containing and lithium-containing pressurized water reactors. These methods are not suitable for small nuclear reactors without boron regulation systems. In addition, the traditional method needs to add boron acid and other substances to adjust the pH value of the coolant, which will introduce impurities into the coolant and may cause damage to the primary circuit pipe base material, thereby affecting the normal operation of the reactor.

[0040] Based on this, some embodiments of the present application provide a control method for activating corrosion product source terms in a boron-free nuclear reactor, comprising the following steps:

[0041] During the shutdown of the boron-free nuclear reactor, the temperature of the coolant in the primary circuit of the boron-free nuclear reactor is reduced to a first temperature, and H2O2 solution is injected into the coolant in the primary circuit for oxidation operation;

[0042] In the oxidation operation, the concentration of H2O2 in the coolant in the primary circuit is within a set concentration range;

[0043] The pH value of the coolant in the primary loop is 9.3-9.7, and the set concentration of H2O2 in the coolant in the primary loop is 18 mg / kg-20 mg / kg.

[0044] The application uses H2O2 as an oxidizing agent, and controls the concentration of H2O2 in the oxidation process within a set range, so that it can continuously oxidize the activated corrosion products under the condition that the pH value is 9.3-9.7; thereby improving the oxidation effect of the oxidizing agent on the activated corrosion products in the coolant, and further reducing the residual amount of the corrosion products in the primary loop and causing less damage to the nuclear reactor components. The control method of the activated corrosion product source term of the boron-free nuclear reactor of the application does not need to use a pH adjuster such as boric acid to adjust the pH value of the coolant in the primary loop, and can save the subsequent step of removing the pH adjuster; therefore, the method of the application can be applied to a boron-free nuclear reactor.

[0045] It should be noted that the composition of the coolant in the primary loop is not particularly limited in the application, as long as it does not contain boron components.

[0046] For example, the pH value of the coolant in the primary loop can be 9.3, 9.4, 9.5, 9.6, 9.7, or any value within the range formed by any two of the above values.

[0047] It can be understood that without adding an external substance for treatment, the pH value of the primary loop coolant of the pressurized water reactor is usually 9.3-9.7, i.e., the method of the application can directly perform efficient oxidation operation on the coolant without adjusting the pH value of the coolant.

[0048] Further, the pH value of the coolant in the primary loop is 9.5.

[0049] For example, the set concentration of H2O2 in the coolant in the primary loop can be 18 mg / kg, 18.1 mg / kg, 18.2 mg / kg, 18.3 mg / kg, 18.4 mg / kg, 18.5 mg / kg, 18.6 mg / kg, 18.7 mg / kg, 18.8 mg / kg, 18.9 mg / kg, 19 mg / kg, 19.1 mg / kg, 19.2 mg / kg, 19.3 mg / kg, 19.4 mg / kg, 19.5 mg / kg, 19.6 mg / kg, 19.7 mg / kg, 19.8 mg / kg, 19.9 mg / kg, or 20 mg / kg.

[0050] It can be understood that controlling the concentration of H2O2 in the oxidation process within the above range can not only maintain good oxidation effect on the activated corrosion products, but also will not cause damage to the primary loop pipe base material.

[0051] In some embodiments, the temperature of the coolant in the primary loop of the boron-free nuclear reactor is reduced to the first temperature while the pressure of the primary loop of the reactor is reduced.

[0052] In some embodiments, in the oxidation operation, the H2O2 solution is injected for more than two times to maintain the concentration of H2O2 in the coolant in the primary loop within the set range.

[0053] For example, the H2O2 solution can be injected for two, three, four, five, six or more times. It can be understood that the present application adds the H2O2 solution in batches to maintain the concentration of H2O2 in the coolant in the primary loop within the set range during the oxidation operation, so that the activated corrosion products can be continuously oxidized, thereby maintaining good oxidation effect.

[0054] In some embodiments, the oxidation operation method further comprises the following steps:

[0055] During the oxidation operation, the concentration of H2O2 in the coolant in the primary loop is measured every set time interval;

[0056] If the measured concentration is lower than the set concentration, the H2O2 solution is injected to maintain the concentration of H2O2 in the coolant in the primary loop within the set range.

[0057] It can be understood that after the first injection of the H2O2 solution, the concentration of H2O2 in the coolant is measured every set time interval to determine whether it is maintained within the set range. If it is lower than the lower limit of the set value, the H2O2 solution is injected again into the primary loop until the concentration reaches the set concentration, and finally the concentration of H2O2 in the coolant is overall balanced and stable.

[0058] In some embodiments, the set time interval is 30 min to 60 min.

[0059] For example, the set time interval can be 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min, 40 min, 41 min, 42 min, 43 min, 44 min, 45 min, 46 min, 47 min, 48 min, 49 min, 50 min, 51 min, 52 min, 53 min, 54 min, 55 min, 56 min, 57 min, 58 min, 59 min, 60 min, or any value within the range formed by any two of the above values.

[0060] Further, the set time interval is 30 min or 60 min.

[0061] In some examples, the concentration of H2O2 in the primary coolant is measured at 30 min, 60 min, 90 min and 150 min after the first injection of the H2O2 solution.

[0062] In some embodiments, the mass fraction of H2O2 in the H2O2 solution is 20% to 40%. For example, the mass fraction of H2O2 in the H2O2 solution can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, or any value within a range defined by any two of the above values.

[0063] Further, the mass fraction of H2O2 in the H2O2 solution is 30%.

[0064] In some examples, the solvent of the H2O2 solution comprises water.

[0065] In some embodiments, the concentration of H2 in the primary coolant is reduced to less than or equal to 3 mg / kg. For example, the reduced concentration of H2 in the primary coolant can be 0.1 mg / kg, 0.2 mg / kg, 0.3 mg / kg, 0.4 mg / kg, 0.5 mg / kg, 0.6 mg / kg, 0.7 mg / kg, 0.8 mg / kg, 0.9 mg / kg, 1.0 mg / kg, 1.1 mg / kg, 1.2 mg / kg, 1.3 mg / kg, 1.4 mg / kg, 1.5 mg / kg, 1.6 mg / kg, 1.7 mg / kg, 1.8 mg / kg, 1.9 mg / kg, 2.0 mg / kg, 2.1 mg / kg, 2.2 mg / kg, 2.3 mg / kg, 2.4 mg / kg, 2.5 mg / kg, 2.6 mg / kg, 2.7 mg / kg, 2.8 mg / kg, 2.9 mg / kg, 3.0 mg / kg, or any value within a range defined by any two of the above values.

[0066] In some embodiments, the concentration of O2 in the primary coolant is less than or equal to 0.1 mg / kg.

[0067] It can be understood that the concentration of O2 in the primary coolant refers to the concentration of O2 during normal operation and the pre-shutdown process of the nuclear reactor; before the H2O2 solution is added, the concentration of H2 in the primary coolant is reduced to a certain range, which can reduce the reaction between H2 and O2 generated by the decomposition of H2O2, and can reduce the explosion or material corrosion and oxidation. That is, by controlling the concentration of H2, the concentration of O2 can be indirectly controlled.

[0068] In some embodiments, the concentration of H2 in the coolant in the primary loop is reduced by introducing N2 into the primary loop.

[0069] It can be understood that after N2 is introduced into the primary loop, the total volume of the gas in the primary loop increases, so that the volume proportion of H2 decreases, thereby achieving the purpose of reducing the concentration of H2. In the method of the present application, the gas used to reduce the concentration of H2 is not limited to N2, but can also be other gases commonly used in the art, as long as it does not react with H2 and can achieve the purpose of reducing the concentration of H2.

[0070] In some embodiments, the step of reducing the temperature of the coolant in the primary loop of the boron-free nuclear reactor to a first temperature comprises:

[0071] After the temperature of the coolant in the primary loop of the boron-free nuclear reactor is reduced to a second temperature, the concentration of H2 in the coolant in the primary loop is reduced, and then the temperature of the coolant in the primary loop is reduced from the second temperature to the first temperature.

[0072] In some embodiments, the first temperature is 80-90℃. As an example, the first temperature can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, or any value within the range formed by any two of the above point values.

[0073] Further, the first temperature is 80℃.

[0074] In some embodiments, the second temperature is 170-180℃. As an example, the second temperature can be 170℃, 171℃, 172℃, 173℃, 174℃, 175℃, 176℃, 177℃, 178℃, 179℃, 180℃, or any value within the range formed by any two of the above point values.

[0075] Further, the second temperature is 170℃.

[0076] In some embodiments, the oxidation operation time is 4-6h. As an example, the oxidation operation time can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.7h, 4.8h, 4.9h, 5h, 5.1h, 5.2h, 5.3h, 5.4h, 5.5h, 5.6h, 5.7h, 5.8h, 5.9h, 6h, or any value within the range formed by any two of the above point values.

[0077] The method of the boron-free nuclear reactor of the present application does not need to add boric acid or use a cation resin bed to remove lithium to adjust the pH value during the shutdown oxidation operation, so that impurities are not introduced and the subsequent purification process can be simplified; the method of the present application has good oxidation effect on activated corrosion products, and can effectively remove the corrosion products; at the same time, the method of the present application is simple to operate, does not need to additionally equip devices and reagents, and can effectively save costs.

[0078] The present application will be further described below in combination with specific examples and comparative examples, but should not be understood as limiting the protection scope of the present application. The raw materials involved in the following specific examples, if not specifically stated, can be sourced from the market, and the instruments used, if not specifically stated, can be sourced from the market, and the processes involved, if not specifically stated, are the routine choices of those skilled in the art.

[0079] Example 1

[0080] Under the simulated conditions of the chemical environment of the coolant water in the primary loop of the boron-free nuclear reactor during shutdown at a pH value of 9.5, after the temperature of the coolant in the primary loop is reduced to 170°C (the second temperature), N2 is introduced to reduce the H2 concentration in the coolant in the primary loop, when the H2 concentration is reduced to 3 mg / kg, the temperature of the coolant in the primary loop is continuously reduced to 80°C (the first temperature), then a H2O2 solution with a mass concentration of 30% is injected into the primary loop, and the oxidation operation of the coolant in the primary loop is started, and the operation time is 4 h.

[0081] After the first injection of the H2O2 solution, samples are taken at 30 min, 60 min, 90 min and 150 min after the first injection to monitor whether the H2O2 concentration in the coolant is maintained at the set value, if it is lower than the lower limit of the set value, the primary loop is supplemented with H2O2 solution to reach the predetermined concentration, so that the H2O2 concentration in the coolant in the primary loop is maintained within the range of 18 mg / kg to 20 mg / kg.

[0082] After the oxidation operation is completed, the residual amount of corrosion products in the corrosion coupons of different component materials (304 stainless steel, 308L stainless steel and 690 nickel-based alloy) in the primary loop is detected.

[0083] Figure 1 Fig. A, B and C are SEM images of the corrosion coupons of 304 stainless steel, 308L stainless steel and 690 nickel-based alloy after oxidation according to the method described in Example 1.

[0084] Comparative Example 1

[0085] The same as Example 1, the only difference is that the pH condition of the coolant in the simulated loop is different, specifically, the Li +The concentration of lithium was reduced from 0.45 mg / kg to 0.04 mg / kg, and the pH value of the coolant was reduced from 9.5 to 8.5. The remaining steps and parameters were consistent with Example 1.

[0086] Comparative Example 2

[0087] The same as Example 1, the only difference is that the pH condition of the coolant in the simulated loop is different, specifically, the pH value of the coolant in the simulated loop is reduced from 9.5 to 4.8 by adding boric acid. The remaining steps and parameters are consistent with Example 1.

[0088] Figure 2 Figures A, B and C are SEM images of 304 stainless steel, 308L stainless steel and 690 nickel-based alloy after oxidation according to the method described in Comparative Example 2.

[0089] The removal results of the corrosion products in the 304 stainless steel, 308L stainless steel and 690 nickel-based alloy corrosion coupons in the above examples and comparative examples are shown in Table 1.

[0090] Wherein, the weight loss rate = (X1-X2) / X1*100%.

[0091] X1 is the weight of the sample before oxidation, in g; X2 is the weight of the sample after oxidation and demolding, in g.

[0092] Table 1

[0093]

[0094] As can be seen from Table 1, in Comparative Example 1, by removing lithium in the coolant to reduce the pH value to 8.5, not only the reaction steps become complex, but also the removal rate of corrosion products in 304 stainless steel and 308L stainless steel is reduced.

[0095] As can be seen from Table 1, Figure 1 and Figure 2 Comparative Example 2, after adding boric acid in the coolant, caused obvious corrosion damage to the equipment component materials, which will affect the service life of the nuclear reactor equipment; and after adding boric acid in the coolant, subsequent recovery and removal of boron element is required, making the reaction more complex and increasing the reaction cost.

[0096] The technical features of the above-described examples can be combined arbitrarily, and in order to make the description simple, not all possible combinations of the technical features in the above-described examples are described, however, as long as the combination of these technical features does not exist contradictory, it should be considered as the scope of the present disclosure.

[0097] The above embodiments only express several implementation ways of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for controlling the source term of activated corrosion products in a boron-free nuclear reactor, characterized in that: The steps include: During the shutdown of the boron-free nuclear reactor, the temperature of the coolant in the primary circuit of the boron-free nuclear reactor is reduced to a first temperature, and an H2O2 solution is injected into the coolant in the primary circuit to perform an oxidation operation; During the oxidation operation, the concentration of H2O2 in the coolant in the primary circuit is kept within a set concentration range; The pH value of the coolant in the primary circuit is 9.3-9.7, and the set concentration of H2O2 in the coolant in the primary circuit is 18 mg / kg-20 mg / kg.

2. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to claim 1, characterized in that: During the oxidation operation, the H2O2 solution is injected at least twice to ensure that the concentration of H2O2 in the coolant in one circuit is within the set concentration range.

3. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to claim 2, characterized in that: The control method further comprises the following steps: During the oxidation operation, the concentration of H2O2 in the coolant in the primary circuit is measured after each set time interval; If the measured concentration is lower than the set concentration, H2O2 solution is injected to make the concentration of H2O2 in the coolant in the primary circuit within the set concentration range.

4. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to claim 3, characterized in that: The set time is 30 minutes to 60 minutes.

5. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to any one of claims 1 to 4, characterized in that: The mass fraction of H2O2 in the H2O2 solution is 20% to 40%.

6. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to any one of claims 1 to 4, characterized in that: The step of reducing the temperature of the coolant in the primary loop of the boron-free nuclear reactor to a first temperature comprises: After lowering the temperature of the coolant in the primary circuit of the boron-free nuclear reactor to a second temperature, the concentration of H2 in the coolant in the primary circuit is lowered; and then the temperature of the coolant in the primary circuit is lowered from the second temperature to the first temperature.

7. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to claim 6, characterized in that: The first temperature is 80°C to 90°C and / or The second temperature is 170°C to 180°C.

8. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to claim 6, characterized in that: Reduce the H2 concentration in the coolant in the primary circuit to less than or equal to 3 mg / kg.

9. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to claim 6, characterized in that: By introducing N2 into the primary circuit, the concentration of H2 in the coolant in the primary circuit is reduced.

10. The method for controlling the source term of activated corrosion products in a boron-free nuclear reactor according to any one of claims 1 to 4 and 7 to 9, characterized in that: The oxidation operation time is 4h~6h.

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