Sulfate radical control method and system for boric acid storage tank of nuclear power station unit

Abstract

The invention discloses a sulfate radical control method and system for a boric acid storage tank of a nuclear power station unit. The control method comprises the steps that S1, drainage of an overhaul primary loop is conveyed to a TEP boric acid storage tank; s2, boric acid water in a TEP boric acid storage tank is treated by a TEP desalting bed purification unit and an evaporation unit and then is conveyed to an REA boric acid storage tank; s3, boric acid water in the REA boric acid storage tank is conveyed to a PTR desalting bed for treatment through a PTR loading well or a transfer well and then conveyed to a TEP boric acid storage tank, and the step S2 is repeated; s4, boric acid water in the REA boric acid storage tank is conveyed to a TEP boric acid storage tank through an RPE process waste liquid recovery tank; s5, boric acid water in the TEP boric acid storage tank is treated by a TEP desalting bed purification unit and an evaporation unit and then returns to the REA boric acid storage tank. The method comprises the following steps: performing sulfate radical removal purification treatment on the overhaul primary loop drainage on line by using a nuclear power plant system; the problem of high sulfate radical content of nuclear power unit boric acid water is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power water chemistry control, and particularly relates to a method and system for controlling sulfate radicals in a boric acid storage tank of a nuclear power plant unit. Background Art

[0002] In a nuclear power plant, the REA boric acid storage tank plays a crucial role. The REA boric acid storage tank stores all the boric acid required for reactivity control during the normal operation of the unit. During the normal operation of the unit, the REA boric acid storage tank is nearly full at the end of each fuel cycle. When the RCP reaches the boron concentration for refueling shutdown and the pressurizer is full of water, the liquid level of the REA boric acid storage tank reaches the lowest value. At this time, the remaining boric acid capacity should be sufficient to bring the unit back to cold shutdown immediately after starting up to full power. Considering the requirements of boric acid capacity, plant layout, and equipment maintenance, the system is provided with two REA boric acid storage tanks to store the boric acid solution required for reactivity control, and the capacity requirement for each REA boric acid storage tank is 50% of the total system capacity requirement. The two REA boric acid storage tanks are connected or isolated through an intermediate connecting pipeline and its isolation valve. The boric acid dosing tank provides the first injection of 4% boric acid solution for the boric acid storage tank. During the subsequent operation of the unit, the replenishment of the REA boric acid storage tank comes from the boric acid recovered in the TEP evaporation unit.

[0003] However, in a water system with a high oxygen concentration and an irradiation environment, it will be able to generate H 2 O 2 . The greater the dissolved oxygen concentration in water and the stronger the irradiation, the greater the generated H 2 O 2 concentration. During the overhaul downlink, hydrogen peroxide is also artificially added to the primary circuit. Due to the presence of oxidants in water, such as free chlorine, hydrogen peroxide, etc., the cation resin will oxidize and deteriorate during application. The specific mechanism of the resin oxidation process is not yet fully clear. The result of resin oxidation is that the carbon chain between the benzene rings is broken to form benzenesulfonic acid. The hydrolysis reaction of benzenesulfonic acid requires a relatively high temperature and time, and the residual heat and surface temperature of the fuel assembly can promote the hydrolysis of benzenesulfonic acid to form sulfate radicals. Theoretical calculation shows that 192 grams of sulfate radicals will be generated when 1 liter of cation resin is completely oxidized. The processes of hydrogen peroxide generation, resin oxidation, and hydrolysis to produce sulfate radicals are as follows:

[0004]

[0005] In a nuclear power plant, the method for removing sulfate radicals in boric acid water is mainly achieved through desalination bed treatment. Since the RCV desalination bed and the TEP desalination bed release sulfonic groups when treating the boron water containing hydrogen peroxide in the primary circuit, and then the sulfonic groups are thermally decomposed into sulfate radicals in the TEP evaporator, ultimately resulting in a high sulfate radical content in the REA boric acid storage tank. Since the TEP desalination bed cannot handle a large amount of oxygen-containing radioactive boron water and sulfonic groups will be released during the process, it is difficult to treat the sulfate radicals in the REA boric acid tank. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for controlling sulfate radicals in a boric acid storage tank of a nuclear power plant unit and a control system for sulfate radicals in a boric acid storage tank of a nuclear power plant unit.

[0007] The technical solution adopted by the present invention to solve its technical problems is: to provide a method for controlling sulfate radicals in a boric acid storage tank of a nuclear power plant unit, including the following steps:

[0008] S1. Transport the drained water of the primary circuit during the major overhaul of the nuclear power unit to the TEP boric acid storage tank;

[0009] S2. After the boric acid water in the TEP boric acid storage tank is treated by the TEP demineralization bed purification unit and the evaporation unit, it is transported to the REA boric acid storage tank;

[0010] S3. The boric acid water in the REA boric acid storage tank is transported to the PTR demineralization bed for treatment through the PTR loading well or the transfer well, and then transported to the TEP boric acid storage tank, and step S2 is repeated;

[0011] S4. The boric acid water in the REA boric acid storage tank is transported to the TEP boric acid storage tank under an anaerobic environment through the RPE process waste liquid recovery tank;

[0012] S5. After the boric acid water in the TEP boric acid storage tank is treated by the TEP demineralization bed purification unit and the evaporation unit, it returns to the REA boric acid storage tank;

[0013] Steps S4 - S5 are cycled one or more times until the sulfate radical concentration in the boric acid water in the REA boric acid storage tank ≤ 30 ppb.

[0014] In some embodiments, steps S2 - S3 are cycled one or more times.

[0015] In some embodiments, in step S4, after the TEP boric acid storage tank receives the boric acid water from the REA boric acid storage tank, the boron acidity of the boric acid water in the TEP boric acid storage tank is adjusted to ≤ 2000 ppm.

[0016] In some embodiments, in step S3, the boric acid water in the REA boric acid storage tank enters the PTR loading well or the transfer well after being diluted; or, the boric acid water in the REA boric acid storage tank is diluted in the PTR loading well or the transfer well; the dilution multiple corresponds to the volume ratio of the PTR loading well or the transfer well and the REA boric acid storage tank.

[0017] In some embodiments, demineralized water is used to dilute the boric acid water.

[0018] In some embodiments, in step S3, the boric acid concentration of the boric acid water in the PTR loading well or transfer well ≤ 1400 ppm.

[0019] The present invention provides another method for controlling sulfate radicals in a boric acid storage tank of a nuclear power plant unit, including the following steps:

[0020] S1. Transport the drained water of the primary circuit during the major overhaul of the nuclear power unit to the TEP boric acid storage tank;

[0021] S2. After the boric acid water in the TEP boric acid storage tank is treated by the TEP demineralization bed purification unit and the evaporation unit, it is transported to the REA boric acid storage tank;

[0022] S3. Transport the boric acid water in the REA boric acid storage tank to the TEP boric acid storage tank through the RPE process waste liquid recovery tank in an anaerobic environment, and repeat step S2;

[0023] Steps S2 - S3 are cycled one or more times until the sulfate radical concentration in the boric acid water in the REA boric acid storage tank ≤ 30 ppb.

[0024] In some embodiments, in step S3, after the TEP boric acid storage tank receives the boric acid water from the REA boric acid storage tank, adjust the boric acid concentration of the boric acid water in the TEP boric acid storage tank ≤ 2000 ppm.

[0025] The present invention also provides a sulfate radical control system for a boric acid storage tank of a nuclear power plant unit, used for the sulfate radical control method of the boric acid storage tank of a nuclear power plant unit described in any one of the above, and the sulfate radical control system of the boric acid storage tank of a nuclear power plant unit includes an REA boric acid storage tank, a PTR loading well or transfer well, a PTR demineralization bed, a TEP boric acid storage tank, and an RPE process waste liquid recovery tank connected in sequence;

[0026] The TEP boric acid storage tank is also connected to the REA boric acid storage tank, so that the REA boric acid storage tank, the PTR loading well or transfer well, the PTR demineralization bed, and the TEP boric acid storage tank form a first loop; the RPE process waste liquid recovery tank is connected between the REA boric acid storage tank and the TEP boric acid storage tank to provide an anaerobic environment for the circulation of boric acid water between the REA boric acid storage tank and the TEP boric acid storage tank; the TEP boric acid storage tank, the REA boric acid storage tank, and the RPE process waste liquid recovery tank are connected to form a second loop;

[0027] The TEP boric acid storage tank receives the drained water of the primary circuit during the major overhaul of the nuclear power unit, so that the boric acid water enters the first loop and / or the second loop for circulation treatment to reduce the sulfate radical content.

[0028] In some embodiments, the REA boric acid storage tank is connected to the PTR loading well or transfer well through the REA system pipeline and the PTR system pipeline, so that the boric acid water in the REA boric acid storage tank is mixed and diluted with the demineralized water driven by the demineralized water pump under the drive of the REA boric acid delivery pump and then transmitted into the PTR loading well or transfer well.

[0029] Advantages of the present invention: The on-line purification treatment of sulfate in the primary circuit drainage during the major overhaul of the nuclear power plant system is utilized. By connecting the RPE process waste liquid recovery tank between the REA boric acid storage tank and the TEP boric acid storage tank, an oxygen-free transmission pipeline is provided for the boric acid water, improving the sulfate removal effect and reducing the sulfate content of the boric acid water in the REA boric acid storage tank; the transmission process of the boric acid water does not affect the normal function of the system where the transmission pipeline is located. The boric acid water after sulfate removal can be transmitted back to the original system (REA boric acid storage tank) and the water quality is not polluted, and still can meet the water quality requirements of the original system; the problem of high sulfate content in the boric acid water of the nuclear power unit is solved; the waste liquid discharge is reduced, the cost is reduced and the efficiency is increased, saving costs for the power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0031] Figure 1 is a schematic flow chart of a method for controlling sulfate in a boric acid storage tank of a nuclear power plant unit according to an embodiment of the present invention;

[0032] Figure 2 is a schematic connection diagram of a sulfate control system for a boric acid storage tank of a nuclear power plant unit according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In order to have a clearer understanding of the technical features, objectives and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the drawings.

[0034] Combined with Figure 1 and Figure 2 , a method for controlling sulfate in a boric acid storage tank of a nuclear power plant unit according to an embodiment of the present invention may include the following steps:

[0035] S1. Monitor the sulfate content of the primary circuit drainage (i.e., boric acid water) during the major overhaul of the nuclear power unit, and transport the primary circuit drainage of the nuclear power unit during the major overhaul to the TEP (Coolant Storage and Treatment System) boric acid storage tank 10.

[0036] S2. After the boric acid water is treated by the TEP demineralization bed purification unit and the evaporation unit to reduce the sulfate content in the boric acid water, it is then transported to the REA (Reactor Boron and Water Make-up System) boric acid storage tank 20.

[0037] In a nuclear power plant, the REA boric acid storage tank stores all the boric acid required for reactivity control during the normal operation of the unit. In a nuclear power plant unit, usually two boric acid storage tanks are provided to store the boric acid solution required for reactivity control, and the capacity requirement of each boric acid storage tank is 50% of the total system capacity requirement; the two boric acid storage tanks are connected or isolated through an intermediate connecting pipeline and its isolation valve. In step S2, after the boric acid water is treated by the TEP demineralization bed purification unit and the evaporation unit, it is transported to the selected REA boric acid storage tank 20.

[0038] S3. The boric acid water in the REA boric acid storage tank 20 is transported through the PTR (reactor pool and fuel pool cooling and treatment system) loading well or transfer well 30 to the PTR demineralization bed for sulfate purification treatment, and then transported to the TEP boric acid storage tank 10; repeat step S2, that is: the boric acid water in the TEP boric acid storage tank 10 is again treated by the TEP demineralization bed purification unit and the evaporation unit, and then transported to the REA boric acid storage tank 20.

[0039] Among them, the boric acid water in the REA boric acid storage tank 20 enters the PTR loading well or transfer well 30 after dilution; or, the boric acid water in the REA boric acid storage tank 20 is diluted in the PTR loading well or transfer well 30.

[0040] Specifically, the REA boric acid storage tank 20 is connected to the PTR loading well or transfer well 30 through the REA system pipeline and the PTR system pipeline, so the boric acid water can enter the PTR loading well or transfer well 30 through the REA system pipeline and the PTR system pipeline under the drive of the REA boric acid delivery pump. During the transportation of the boric acid water, the boric acid water is mixed and diluted with the demineralized water driven by the demineralized water pump and then transported into the PTR loading well or transfer well 30, so that in the PTR loading well or transfer well 30, the boron acidity of the boric acid water ≤ 1400 ppm, to meet the volume of the PTR loading well or transfer well 30 and ensure the purification efficiency of the subsequent PTR demineralization bed 40.

[0041] The dilution multiple of the boric acid water corresponds to the volume ratio of the PTR loading well or transfer well 30 and the REA boric acid storage tank 20. For example, the volume of the REA boric acid storage tank 20 is 60 L, the volume of the PTR loading well or transfer well 30 is 300 L, and the volume ratio of the two is 1:5, then the boric acid water from the REA boric acid storage tank 20 is diluted by 5 times, so that the volume ratio of the diluted volume to the undiluted volume is 5:1.

[0042] The REA boric acid storage tank 20, the PTR loading well or transfer well 30, the PTR demineralization bed 40 and the TEP boric acid storage tank 10 are connected to form a first loop 100. By repeatedly executing steps S2 - S3, the boric acid water can be circulated and treated in this first loop 100 to gradually remove sulfate. When the boric acid water passes through the PTR demineralization bed 40, it can also be subjected to SRD purification treatment.

[0043] The REA boric acid storage tank 20 is used as a monitoring point to monitor the sulfate content in the boric acid water in the REA boric acid storage tank 20 .

[0044] According to the comparison between the monitored sulfate content and the required range (≤30ppb), when the sulfate content is higher than the required range, steps S2-S3 are executed and circulated once or multiple times, so that the boric acid water is circulated in the first loop 100 formed by connecting the REA boric acid storage tank 20, the PTR loading well or transfer well 30, the PTR desalination bed 40 and the TEP boric acid storage tank 10 to reduce the sulfate content therein.

[0045] In nuclear power plants, hydrogen peroxide is artificially added to the primary circuit when the nuclear power units are being overhauled. The presence of oxidants in the water will cause the resin of the desalting bed to oxidize and deteriorate, and then the carbon chains between the benzene rings will be disconnected to form benzenesulfonic acid. The sulfonic acid group is decomposed into sulfate by heat in the TEP evaporator, resulting in a high sulfate content in the REA boric acid storage tank. Therefore, in order to completely remove sulfate in boric acid water or reduce the sulfate content to meet the requirements of the "Chemical and Radiochemical Technical Specifications" (≤30ppb), it is necessary to prevent the presence or entry of oxygen when removing sulfate.

[0046] According to the requirement of an oxygen-free environment, the sulfate radical control method of a boric acid storage tank of a nuclear power plant unit of the present invention further comprises the following steps:

[0047] S4, transporting the boric acid water in the REA boric acid storage tank 20 to the TEP boric acid storage tank 10 through the RPE process waste liquid recovery tank 50 in an oxygen-free environment.

[0048] Among them, the RPE process waste liquid recovery tank 50 is connected between the REA boric acid storage tank 20 and the TEP boric acid storage tank 10 to provide an oxygen-free transport pipeline for boric acid water. After the TEP boric acid storage tank 10 receives the boric acid water from the RPE process waste liquid recovery tank 50 and the REA boric acid storage tank 20, the boric acid degree of the boric acid water in the TEP boric acid storage tank 10 is regulated to be ≤2000ppm, so as to facilitate the control of the operation of the subsequent TEP desalination bed purification unit and the evaporation unit. The regulation method includes: introducing a circuit water exchange (low concentration boric acid water) into the TEP boric acid storage tank 10, and reducing the boric acid degree of the boric acid water from the REA boric acid storage tank 20 by dilution, so that the boric acid degree is ≤2000ppm. If the boric acid degree of the TEP boric acid storage tank 10 is ≤2000ppm after receiving the boric acid water from the REA boric acid storage tank 20, no regulation is required.

[0049] After the boric acid water in the TEP boric acid storage tank 10 in S5 is subjected to evaporation recovery treatment through the TEP demineralization bed purification unit and the evaporation unit, it returns to the REA boric acid storage tank 20. Since the boric acid water enters the TEP boric acid storage tank 10 through the RPE process waste liquid recovery tank 50, oxygen introduction during transportation is avoided, the release of sulfonic acid groups is avoided, and the purification efficiency of the sulfate radical in the boric acid water by the TEP demineralization bed purification unit is improved.

[0050] Steps S4 - S5 are cyclically processed once or multiple times until the sulfate radical concentration in the boric acid water in the REA boric acid storage tank ≤ 30 ppb.

[0051] The RPE process waste liquid recovery tank 50 is connected between the REA boric acid storage tank 20 and the TEP boric acid storage tank 10, and is also connected to the REA boric acid storage tank 20 and the TEP boric acid storage tank 10 to form a second loop 200. When steps S5 - S6 are repeatedly executed, that is, to drive the boric acid water to circulate in the second loop 200 for sulfate radical purification treatment until the sulfate radical content is reduced to 30 ppb or below.

[0052] Preferably, after the boric acid water enters the TEP boric acid storage tank 10 through the RPE process waste liquid recovery tank 50 each time, it is mixed and diluted with the water changed in the primary loop, so that the boron acidity ≤ 2000 ppm, and then returns to the REA boric acid storage tank 20 after being processed by the TEP demineralization bed purification unit and the evaporation unit.

[0053] In some embodiments, when the sulfate radical concentration of the boric acid water in the REA boric acid storage tank 20 is higher than 30 ppb, steps S4 and S5 are executed.

[0054] The sulfate radical control method for the boric acid storage tank of the nuclear power plant unit in another embodiment of the present invention includes the following steps:

[0055] S1. Monitor the sulfate radical content of the drained water from the primary loop (i.e., boric acid water) during the major overhaul of the nuclear power unit, and transport the drained water from the primary loop during the major overhaul of the nuclear power unit to the TEP boric acid storage tank.

[0056] S2. After the boric acid water is subjected to evaporation recovery treatment through the TEP demineralization bed purification unit and the evaporation unit, it is transported to the REA boric acid storage tank.

[0057] S3. Transport the boric acid water in the REA boric acid storage tank to the TEP boric acid storage tank through the RPE process waste liquid recovery tank in an oxygen - free environment; repeat step S2, that is: the boric acid water in the TEP boric acid storage tank is processed by the TEP demineralization bed purification unit and the evaporation unit again, and then transported to the REA boric acid storage tank. Since the boric acid water enters the TEP boric acid storage tank through the RPE process waste liquid recovery tank, oxygen introduction during transportation is avoided, the release of sulfonic acid groups is avoided, and the purification efficiency of the sulfate radical in the boric acid water by the TEP demineralization bed purification unit is improved.

[0058] Steps S2 - S3 are cyclically processed once or multiple times until the sulfate ion concentration in the boric acid water in the REA boric acid storage tank ≤ 30 ppb. Among them, the RPE process waste liquid recovery tank is connected between the REA boric acid storage tank and the TEP boric acid storage tank, providing an anaerobic pipeline for the boric acid water and also forming a loop with the REA boric acid storage tank and the TEP boric acid storage tank (such as Figure 2 shown in the second loop 200 in

[0059] . When repeating steps S2 - S3, that is, driving the boric acid water to circulate in this loop for sulfate ion purification treatment until the sulfate ion content is reduced to 30 ppb or below.

[0060] Combined with Figure 1 and Figure 2 , a sulfate ion control system for the boric acid storage tank of a nuclear power plant unit for implementing the above - mentioned sulfate ion control method for the boric acid storage tank of a nuclear power plant unit may include a REA boric acid storage tank 20, a PTR loading well or transfer well 30, a PTR desalination bed 40, and a TEP boric acid storage tank 10 connected in sequence. The TEP boric acid storage tank 10 is also connected to the REA boric acid storage tank 20, so that the REA boric acid storage tank 20, the PTR loading well or transfer well 30, the PTR desalination bed 40, and the TEP boric acid storage tank 10 form a first loop 100.

[0061] The TEP boric acid storage tank 10 receives the drained water from the primary loop during the major overhaul of the nuclear power unit, enabling the boric acid water to enter the first loop for circulation treatment to reduce the sulfate ion content.

[0062] During the process of transporting the boric acid water from the TEP boric acid storage tank 10 to the REA boric acid storage tank 20, after being treated by the TEP desalination bed purification unit and the evaporation unit, it then enters the REA boric acid storage tank 20.

[0063] Specifically, the REA boric acid storage tank 20 is connected to the PTR loading well or transfer well 30 through the REA system pipeline and the PTR system pipeline, so that the boric acid water in the REA boric acid storage tank 20 is mixed and diluted with the demineralized water pumped by the demineralized water pump under the drive of the REA boric acid delivery pump and then transmitted into the PTR loading well or transfer well 30.

[0064] In the PTR loading well or transfer well, the boron acidity of the boric acid water ≤ 1400 ppm to meet the volume of the PTR loading well or transfer well and ensure the purification efficiency of the subsequent PTR demineralization bed.

[0065] In some embodiments, the sulfate control system of the boric acid storage tank of the nuclear power plant unit further includes an RPE process waste liquid recovery tank 50. The RPE process waste liquid recovery tank 50 is connected between the REA boric acid storage tank 20 and the TEP boric acid storage tank 10 to provide an anaerobic environment for the circulation of the boric acid water between the REA boric acid storage tank 20 and the TEP boric acid storage tank 10. The TEP boric acid storage tank 10, the REA boric acid storage tank 20 and the RPE process waste liquid recovery tank 50 are connected to form a second loop 200.

[0066] After the TEP boric acid storage tank 10 receives the boric acid water from the RPE process waste liquid recovery tank 50 and the REA boric acid storage tank 20, the boron acidity of the boric acid water in the TEP boric acid storage tank 10 can be made ≤ 2000 ppm by introducing the primary loop water change (low-concentration boric acid water) into the TEP boric acid storage tank 10. The boric acid water with a boron acidity ≤ 2000 ppm after dilution is then processed by the TEP demineralization bed purification unit and the evaporation unit and then returned to the REA boric acid storage tank 20.

[0067] According to the selected different sulfate control methods for the boric acid storage tank of the nuclear power plant unit, start Figure 2 the different loops of the sulfate control system of the boric acid storage tank of the nuclear power plant unit as shown. For example, when the sulfate control method is executed according to the process of the embodiment shown in Figure 1 , both the first loop and the second loop of the control system shown in Figure 2 are put into application. When the sulfate control method is executed along the anaerobic path, the second loop of the control system shown in Figure 2 is put into application.

[0068] In summary, the sulfate control system of the boric acid storage tank of the nuclear power plant unit of the present invention is the original system of the nuclear power plant unit, which realizes the online removal and purification treatment of sulfate in boric acid water, has simple operation, high efficiency, reduces waste liquid discharge, reduces costs and increases efficiency, and saves costs for the power station.

[0069] The above are only embodiments of the present invention, and thus do not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall similarly be included within the patent protection scope of the present invention.

Claims

1. A method for controlling sulfate radicals in a boric acid storage tank of a nuclear power plant unit, characterized in that: The following steps are involved: S1. Transport the primary circuit drainage of the nuclear power unit overhaul to the TEP boric acid storage tank; S2, the boric acid water in the TEP boric acid storage tank is treated by the TEP desalting bed purification unit and the evaporation unit and then transported to the REA boric acid storage tank; S3, transporting the boric acid water in the REA boric acid storage tank to the PTR desalting bed through the PTR loading well or transfer well for treatment, and then transporting it to the TEP boric acid storage tank, and repeating step S2; S4, transporting the boric acid water in the REA boric acid storage tank to the TEP boric acid storage tank in an oxygen-free environment via the RPE process waste liquid recovery tank; S5, the boric acid water in the TEP boric acid storage tank is treated by the TEP desalination bed purification unit and the evaporation unit, and then returned to the REA boric acid storage tank; Steps S4-S5 are cyclically processed once or multiple times until the sulfate concentration in the boric acid water in the REA boric acid storage tank is ≤30 ppb.

2. The sulfate control method of the boric acid storage tank of a nuclear power plant unit according to claim 1, characterized in that: Steps S2-S3 are processed in a loop once or multiple times.

3. The sulfate control method of the boric acid storage tank of a nuclear power plant unit according to claim 1, characterized in that: In step S4, after the TEP boric acid storage tank receives the boric acid water from the REA boric acid storage tank, the boric acid degree of the boric acid water in the TEP boric acid storage tank is regulated to be ≤2000 ppm.

4. The sulfate control method for a boric acid storage tank of a nuclear power plant unit according to any one of claims 1 to 3, characterized in that: In step S3, the boric acid water in the REA boric acid storage tank enters the PTR loading well or transfer well after dilution; or, the boric acid water in the REA boric acid storage tank is diluted in the PTR loading well or transfer well; the dilution multiple corresponds to the volume ratio of the PTR loading well or transfer well and the REA boric acid storage tank.

5. The sulfate control method of the boric acid storage tank of a nuclear power plant unit according to claim 4, characterized in that: The boric acid water is diluted with demineralized water.

6. The sulfate control method of the boric acid storage tank of a nuclear power plant unit according to any one of claims 1 to 3, characterized in that: In step S3, the boric acid content of the boric acid water in the PTR loading well or the transfer well is ≤1400 ppm.

7. A method for controlling sulfate radicals in a boric acid storage tank of a nuclear power plant unit, characterized in that: The following steps are involved: S1. Transport the primary circuit drainage of the nuclear power unit overhaul to the TEP boric acid storage tank; S2, the boric acid water in the TEP boric acid storage tank is treated by the TEP desalting bed purification unit and the evaporation unit, and then transported to the REA boric acid storage tank; S3, transporting the boric acid water in the REA boric acid storage tank to the TEP boric acid storage tank via the RPE process waste liquid recovery tank in an oxygen-free environment, and repeating step S2; Steps S2-S3 are cyclically processed once or multiple times until the sulfate concentration in the boric acid water in the REA boric acid storage tank is ≤30 ppb.

8. The sulfate control method of the boric acid storage tank of a nuclear power plant unit according to claim 7, characterized in that: In step S3, after the TEP boric acid storage tank receives the boric acid water from the REA boric acid storage tank, the boric acid degree of the boric acid water in the TEP boric acid storage tank is regulated to be ≤2000 ppm.

9. A sulfate control system for a boric acid storage tank of a nuclear power plant unit, characterized in that: A sulfate control method for a boric acid storage tank of a nuclear power plant unit according to any one of claims 1 to 7 or a sulfate control method for a boric acid storage tank of a nuclear power plant unit according to claim 8, wherein the sulfate control system of the boric acid storage tank of the nuclear power plant unit comprises a REA boric acid storage tank, a PTR loading well or a transfer well, a PTR desalting bed, a TEP boric acid storage tank, and an RPE process waste liquid recovery tank connected in sequence; The TEP boric acid storage tank is also connected to the REA boric acid storage tank, so that the REA boric acid storage tank, the PTR loading well or transfer well, the PTR desalination bed and the TEP boric acid storage tank form a first loop; the RPE process waste liquid recovery tank is connected between the REA boric acid storage tank and the TEP boric acid storage tank to provide an anaerobic environment for the circulation of boric acid water between the REA boric acid storage tank and the TEP boric acid storage tank; the TEP boric acid storage tank, the REA boric acid storage tank and the RPE process waste liquid recovery tank are connected to form a second loop; The TEP boric acid storage tank receives the primary circuit drainage of the nuclear power unit overhaul, so that the boric acid water enters the first circuit and / or the second circuit for circulation treatment to reduce the sulfate content.

10. The sulfate control system of the boric acid storage tank of a nuclear power plant unit according to claim 9, characterized in that: The REA boric acid storage tank is connected to the PTR loading well or transfer well through the REA system pipeline and the PTR system pipeline, so that the boric acid water in the REA boric acid storage tank is mixed and diluted with the desalted water driven by the desalted water pump under the drive of the REA boric acid delivery pump and then transmitted into the PTR loading well or transfer well.

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