A boric acid solution recovery system and method for a nuclear power plant

Abstract

The present invention relates to the field of nuclear power plant reactor operation, and more particularly to a boric acid solution recovery system and method for nuclear power plants. The system comprises a front storage tank, one end of which is connected to the reactor's primary circuit, and the other end of which is sequentially connected to an intermediate storage tank, an evaporator, a boric acid storage tank, and a refueling water tank. At least three intermediate storage tanks are connected in parallel, and a bidirectional boron transfer pipeline is provided between the intermediate storage tanks and the refueling water tank. The reactor water pool, component pool, and loading well are each connected to the refueling water tank. The present invention achieves the effects of recovering boric acid solution, avoiding environmental pollution, and shortening overhaul construction periods.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power plant reactor operation, and in particular to a boric acid solution recovery system and method for a nuclear power plant. Background Art

[0002] Boric acid is widely used in nuclear power plants to control reactor reactivity. To recover the boric acid solution discharged from the reactor's primary circuit, nuclear power plants are designed with a boric acid solution recovery system.

[0003] According to the original design of the boric acid solution recovery system, its working process is to first collect the boric acid solution discharged from the first loop of the reactor, then evaporate and concentrate it into a high-concentration boric acid solution, and then transfer it into the boric acid solution storage tank for storage. Finally, as needed, high-concentration boric acid solution is injected into the first loop of the reactor and 2400ppm concentration boric acid solution is configured into the refueling water tank, thereby achieving the purpose of boric acid solution recovery.

[0004] The process of evaporating and concentrating the boric acid solution discharged from the reactor's primary circuit into a high-concentration boric acid solution takes a long time. As a result, during short overhauls at nuclear power plants, the evaporated and concentrated high-concentration boric acid solution cannot be transferred to the boric acid solution storage tank for storage and recovery. This is because, before the evaporation and concentration work is completed during a short overhaul, the boric acid solution storage tank has already been filled with high-concentration boric acid solution through other methods according to the unit operating conditions. As a result, the evaporated and concentrated high-concentration boric acid solution cannot be recovered and can only be discharged into the environment as production wastewater, resulting in boric acid waste and environmental pollution. Therefore, during short overhauls, the nuclear power plant's boric acid solution recovery system is unable to achieve its purpose of recovering boric acid solution.

[0005] Furthermore, according to nuclear power plant safety requirements, the lap welds at the bottom of the refueling water tank require regular, comprehensive inspections. This comprehensive inspection requires draining the boric acid solution from the refueling water tank. Current methods either discharge all of the boric acid solution from the refueling water tank to the environment or partially recover it. Discharging all of the boric acid solution to the environment results in boric acid waste and environmental pollution. The partial recovery method involves temporarily storing a portion of the boric acid solution in the refueling water tank in the reactor pool and discharging the remaining portion as wastewater. After the refueling water tank is drained and overhauled, the boric acid solution temporarily stored in the reactor pool is transferred back to the refueling water tank. However, because the reactor pool is connected to the primary reactor circuit, the temporary storage of the boric acid solution in the refueling water tank prevents draining the primary reactor circuit and preventing maintenance of related equipment. Maintenance of primary reactor circuit equipment is one of the most time-consuming tasks during a nuclear power plant overhaul, leading to extended overhaul periods. Furthermore, the discharge of the remaining boric acid solution from the refueling water tank into the environment still poses the problem of boric acid waste and environmental pollution. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a boric acid solution recovery system and method for a nuclear power plant, which achieves the effects of recovering the boric acid solution, avoiding environmental pollution and shortening the overhaul period.

[0007] The present invention provides a boric acid solution recovery system for a nuclear power plant, comprising:

[0008] The front storage tank has one end connected to the reactor primary circuit, and the other end is connected in sequence to the intermediate storage tank, evaporator, boric acid storage tank and refueling water tank;

[0009] There are at least three intermediate storage tanks connected in parallel;

[0010] A two-way boron transfer pipeline is set between the intermediate storage tank and the refueling water tank;

[0011] The reactor water pool, component pool and loading well are respectively connected to the refueling water tank.

[0012] In a specific embodiment of the present invention, the bidirectional boron transfer pipeline includes three branches;

[0013] The two ends of the first branch are the intermediate storage tank and the refueling water tank;

[0014] The first branch is provided with a first valve, a second valve, a boron transfer pump, a third valve and a fourth valve in sequence;

[0015] One end of the second branch is connected between the first valve and the second valve, and the other end is connected to the outlet of the boron transfer pump; a fifth valve is provided on the second branch;

[0016] One end of the third branch is connected to the inlet end of the boron transfer pump, and the other end is connected between the third valve and the fourth valve; a sixth valve is arranged on the third branch.

[0017] In a specific embodiment of the present invention, a detachable airlock door is installed between the reactor water pool and the component pool.

[0018] The present invention provides a method for recovering boric acid solution in a nuclear power plant, comprising: recovering the boric acid solution discharged from the primary circuit of the reactor and recovering the boric acid solution in the refueling water tank;

[0019] The recovery of the boric acid solution discharged from the primary loop of the reactor is specifically as follows:

[0020] Determine the concentration of the boric acid solution discharged from the reactor's primary circuit. If it is less than 2400 ppm, concentrate the discharged boric acid solution to 2400 ppm in an evaporator and then store it in a boric acid storage tank until the refueling water tank is available.

[0021] If the concentration of the boric acid solution discharged from the reactor primary circuit is equal to 2400 ppm, the discharged boric acid solution shall be stored in any two intermediate storage tanks of sufficient capacity until it is transferred to the refueling water tank after it becomes available;

[0022] The recovery of boric acid solution in the refueling water tank is as follows:

[0023] Before unloading, transfer part of the boric acid solution in the refueling water tank to the reactor water pool and component pool until the reactor water pool and component pool are full;

[0024] After the reactor is unloaded, only the boric acid solution in the reactor pool is returned to the refueling tank;

[0025] Before the refueling water tank is overhauled, part of the boric acid solution in the refueling water tank is transferred to any two intermediate storage tanks with sufficient capacity through a two-way boron transfer pipeline until the two intermediate storage tanks are full, and the remaining boric acid solution in the refueling water tank is transferred to the loading well;

[0026] After the refueling water tank is overhauled, the boric acid solution in the intermediate storage tank is transferred back to the refueling water tank through the two-way boron transfer pipeline;

[0027] Return the boric acid solution in the loading well to the refueling water tank;

[0028] Before loading the reactor, a portion of the boric acid solution in the refueling tank is transferred to the reactor pool until the reactor pool is full;

[0029] After the reactor is loaded, the boric acid solution in the reactor water pool and component pool is returned to the refueling tank.

[0030] In a specific embodiment of the present invention, the operating condition in which the concentration of the boric acid solution discharged from the primary circuit of the reactor is less than 2400 ppm includes: a period from when the concentration of the boric acid solution discharged from the primary circuit of the reactor is less than 2400 ppm during reactor startup to when the concentration of the boric acid solution discharged from the primary circuit of the reactor reaches 2400 ppm during reactor shutdown;

[0031] The operating condition in which the concentration of the boric acid solution discharged from the primary loop of the reactor is equal to 2400 ppm includes: the period from when the concentration of the boric acid solution discharged from the primary loop of the reactor reaches 2400 ppm during reactor shutdown to when the concentration of the boric acid solution discharged from the primary loop of the reactor is less than 2400 ppm during reactor startup.

[0032] In a specific embodiment of the present invention, after the reactor is unloaded, an airlock door is installed between the reactor water pool and the component pool. The boric acid solution in the component pool is not returned to the refueling water tank, and only the boric acid solution in the reactor water pool is returned to the refueling water tank.

[0033] In a specific embodiment of the present invention, before loading the reactor, a portion of the boric acid solution in the refueling water tank is transferred to the reactor water pool until the reactor water pool is full, and the airlock door between the reactor water pool and the component pool is removed.

[0034] In a specific embodiment of the present invention, when recovering the boric acid solution discharged from the primary circuit of the reactor;

[0035] If the concentration of the boric acid solution discharged from the reactor primary circuit is equal to 2400 ppm, the discharged boric acid solution shall be stored in any two intermediate storage tanks with sufficient capacity;

[0036] When the refueling water tank does not need to be repaired, the boric acid solution is directly transferred to the refueling water tank through the two-way boron transfer pipeline;

[0037] When the refueling water tank needs to be repaired, the boric acid solution is transferred to the refueling water tank through the two-way boron transfer pipeline after the repair is completed.

[0038] In a specific embodiment of the present invention, when recovering the boric acid solution in the refueling water tank, before the refueling water tank is overhauled, a portion of the boric acid solution in the refueling water tank is transferred to any two intermediate storage tanks with sufficient capacity through a two-way boron transfer pipeline;

[0039] The operation method of the two-way boron transfer pipeline is:

[0040] The first valve, the fourth valve, the fifth valve and the sixth valve are opened; the second valve and the third valve are closed, and the boron transfer pump is started;

[0041] When the boric acid solution in the refueling water tank is recovered, after the refueling water tank is overhauled, the boric acid solution in the intermediate storage tank is returned to the refueling water tank through the two-way boron transfer pipeline. The operation method of the two-way boron transfer pipeline is as follows:

[0042] The first valve, the second valve, the third valve and the fourth valve are opened; the fifth valve and the sixth valve are closed, and the boron transfer pump is started.

[0043] Compared with the prior art, the boric acid solution recovery system and method for nuclear power plants of the present invention have the following beneficial effects:

[0044] (1) The boric acid solution discharged from the reactor primary circuit is divided into two recovery methods according to its concentration. For the boric acid solution with a concentration of less than 2400 ppm discharged from the reactor primary circuit, the target boron concentration of evaporation concentration is reduced from a high concentration to 2400 ppm, which shortens the evaporation concentration time and improves the recovery efficiency of the boric acid solution with a concentration of less than 2400 ppm. The purpose of recovering the boric acid solution with a concentration of less than 2400 ppm discharged from the reactor primary circuit is achieved during a short overhaul of a nuclear power plant;

[0045] (2) For the boric acid solution with a concentration of 2400ppm discharged from the reactor primary circuit, instead of evaporation and concentration, a two-way boron transfer pipeline is added between the intermediate storage tank and the refueling water tank, so that the boric acid solution with a concentration of 2400ppm discharged from the reactor primary circuit is directly transferred from the intermediate storage tank to the refueling water tank, thereby improving the efficiency of recovering the boric acid solution with a concentration of 2400ppm. During the short overhaul of the nuclear power plant, the purpose of recovering the boric acid solution with a concentration of 2400ppm discharged from the reactor primary circuit is achieved.

[0046] (3) When the refueling water tank is emptied for maintenance, the storage space of the component pool is used. By installing an airlock door between the reactor water pool and the component pool, a portion of the boric acid solution in the refueling water tank is temporarily stored in the component pool. After the reactor is loaded, the boric acid solution is transferred back to the refueling water tank.

[0047] (4) When the refueling water tank is emptied for maintenance, the storage space of the intermediate storage tank is used. A bidirectional boron transfer pipeline is added between the intermediate storage tank and the refueling water tank to temporarily store a portion of the boric acid solution in the refueling water tank in the intermediate storage tank. After the refueling water tank is emptied for maintenance, the boric acid solution is transferred back to the refueling water tank.

[0048] (5) When the refueling water tank is emptied for maintenance, the storage space of the loading well is used to temporarily store a portion of the boric acid solution in the refueling water tank in the loading well. After the refueling water tank is emptied for maintenance, the boric acid solution is transferred back to the refueling water tank;

[0049] (6) When the refueling water tank is emptied for maintenance, the storage space of the intermediate storage tank, loading well and component pool is sufficient to temporarily store all the boric acid solution in the refueling water tank. The reactor pool does not need to temporarily store part of the boric acid solution in the refueling water tank. The reactor primary circuit can still be emptied for maintenance. The emptying and maintenance work of the refueling water tank does not affect the maintenance work of the related equipment of the reactor primary circuit and will not extend the overhaul period. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 A schematic diagram of a boric acid solution recovery system in a nuclear power plant is shown;

[0051] Figure 2 Schematic diagram of the bidirectional boron transfer pipeline between the intermediate storage tank and the refueling water tank;

[0052] Figure 3 A flow chart showing a method for recovering boric acid solution in a nuclear power plant;

[0053] In the picture:

[0054] 1-reactor primary loop, 2-front storage tank, 3-first intermediate storage tank, 4-second intermediate storage tank, 5-third intermediate storage tank, 6-evaporator, 7-boric acid solution storage tank, 8-reactor water pool, 9-component pool, 10-loading well, 11-refueling water tank, 12-bidirectional boron transfer pipeline, 13-first valve, 14-second valve, 15-fifth valve, 16-third valve, 17-sixth valve, 18-fourth valve, 19-boron transfer pump, 20-airlock door. DETAILED DESCRIPTION

[0055] In order to further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than for limiting the present invention.

[0056] The embodiment of the present invention discloses a boric acid solution recovery system for a nuclear power plant, such as Figure 1 As shown, including:

[0057] The front storage tank 2 has one end connected to the reactor primary circuit 1, and the other end is connected in sequence to the intermediate storage tank, the evaporator 6, the boric acid solution storage tank 7 and the refueling water tank 11;

[0058] The intermediate storage tanks are at least three connected in parallel, specifically a first intermediate storage tank 3, a second intermediate storage tank 4, and a third intermediate storage tank 5 connected in parallel;

[0059] A two-way boron transfer pipeline 12 is provided between the intermediate storage tank and the refueling water tank 11;

[0060] The reactor water pool 8, component pool 9 and loading well 10 are respectively connected to the refueling water tank 11;

[0061] A detachable airlock door 20 is provided between the reactor water pool 8 and the component pool 9 .

[0062] like Figure 2 As shown, the bidirectional boron transfer pipeline 12 includes three branches:

[0063] The first branch ends at an intermediate storage tank and a refueling water tank 11;

[0064] The first branch is provided with a first valve 13, a second valve 14, a boron transfer pump 19, a third valve 16 and a fourth valve 18 in sequence;

[0065] One end of the second branch is connected between the first valve 13 and the second valve 14, and the other end is connected to the outlet of the boron transfer pump 19; a fifth valve 15 is provided on the second branch;

[0066] One end of the third branch is connected to the inlet of the boron transfer pump 19 , and the other end is connected between the third valve 16 and the fourth valve 18 ; a sixth valve 17 is provided on the third branch.

[0067] The embodiment of the present invention discloses a method for recovering boric acid solution in a nuclear power plant, such as Figure 3 As shown, including:

[0068] Recovery of boric acid solution discharged from the reactor primary circuit 1 and recovery of boric acid solution in the refueling water tank 11;

[0069] The recovery of the boric acid solution discharged from the reactor primary loop 1 includes:

[0070] Determine the concentration of the boric acid solution discharged from the reactor primary circuit 1. If it is less than 2400 ppm, it is collected in an intermediate storage tank through the front storage tank 2;

[0071] The intermediate storage tank is preferably the first intermediate storage tank 3;

[0072] Then, the boric acid solution with a concentration of less than 2400 ppm in the intermediate storage tank is evaporated and concentrated into a boric acid solution with a concentration of 2400 ppm by an evaporator 6, and stored in a boric acid solution storage tank 7;

[0073] If the refueling water tank 11 does not need to be emptied for maintenance, the 2400 ppm boric acid solution in the boric acid solution storage tank 7 is directly transferred to the refueling water tank 11;

[0074] If the refueling water tank 11 needs to be emptied for maintenance, the boric acid solution with a concentration of 2400 ppm in the boric acid solution storage tank 7 is transferred to the refueling water tank 11 after the emptying and maintenance of the refueling water tank 11 is completed.

[0075] The operating conditions in which the boric acid solution discharged from the reactor primary loop 1 has a concentration of less than 2400 ppm include: the period from when the concentration of the boric acid solution discharged from the reactor primary loop 1 is less than 2400 ppm during reactor startup to when the concentration of the boric acid discharged from the reactor primary loop 1 reaches 2400 ppm during reactor shutdown.

[0076] If the concentration of the boric acid solution discharged from the reactor primary circuit 1 is 2400 ppm, it will be transferred to any two intermediate storage tanks with sufficient capacity through the front storage tank 2;

[0077] The intermediate storage tanks are preferably the second intermediate storage tank 4 and the third intermediate storage tank 5;

[0078] If the refueling water tank 11 does not need to be emptied for maintenance, the 2400ppm concentration of boric acid solution in the intermediate storage tank is directly transferred to the refueling water tank 11 through the two-way boron transfer pipeline 12;

[0079] If the refueling water tank 11 needs to be emptied for maintenance, after the emptying and maintenance of the refueling water tank 11 is completed, the 2400ppm concentration of boric acid solution in the intermediate storage tank is transferred to the refueling water tank 11 through the two-way boron transfer pipeline 12;

[0080] The operating conditions in which the boric acid solution discharged from the reactor primary loop 1 has a concentration equal to 2400 ppm include: the period from when the concentration of the boric acid solution discharged from the reactor primary loop 1 reaches 2400 ppm during reactor shutdown to when the concentration of the boric acid solution discharged from the reactor primary loop 1 becomes less than 2400 ppm during reactor startup.

[0081] The recovery of the boric acid solution in the refueling water tank 11 includes:

[0082] Before unloading the reactor, a portion of the boric acid solution in the refueling water tank 11 is transferred to the reactor water pool 8 and the component pool 9 until the reactor water pool 8 and the component pool 9 are full;

[0083] After the reactor is unloaded, an airlock door 20 is installed between the reactor water pool 8 and the component pool 9 to return only the boric acid solution in the reactor water pool 8 to the refueling water tank 11;

[0084] Drain the reactor primary circuit 1 to carry out maintenance on the reactor primary circuit 1 related equipment;

[0085] Before the refueling water tank 11 is overhauled, a portion of the boric acid solution in the refueling water tank 11 is transferred to any two intermediate storage tanks with sufficient capacity through the two-way boron transfer pipeline 12 until the two intermediate storage tanks are full;

[0086] The intermediate storage tanks are preferably the second intermediate storage tank 4 and the third intermediate storage tank 5;

[0087] Before the refueling water tank 11 is overhauled, the remaining boric acid solution in the refueling water tank 11 is transferred to the loading well 10 until the refueling water tank 11 is emptied;

[0088] After the refueling water tank 11 is overhauled, the boric acid solution in the two intermediate storage tanks is transferred back to the refueling water tank 11 through the two-way boron transfer pipeline 12;

[0089] After the refueling water tank 11 is overhauled, the boric acid solution in the loading well 10 is returned to the refueling water tank 11;

[0090] Before loading the reactor, a portion of the boric acid solution in the refueling water tank 11 is transferred to the reactor water pool 8 until the reactor water pool 8 is full, and the airlock door 20 between the reactor water pool 8 and the component pool 9 is removed.

[0091] After the reactor is loaded, the boric acid solution in the reactor water pool 8 and the component pool 9 is returned to the refueling water tank 11 .

[0092] In order to further understand the present invention, the boric acid solution recovery system and method for a nuclear power plant provided by the present invention are described in detail below in conjunction with the embodiments. The protection scope of the present invention is not limited by the following embodiments.

[0093] Example 1

[0094] Boric acid solution recovery system in nuclear power plants, such as Figure 1 As shown, including:

[0095] The front storage tank 2 has one end connected to the reactor primary circuit 1, and the other end is connected in sequence to the intermediate storage tank, the evaporator 6, the boric acid solution storage tank 7 and the refueling water tank 11;

[0096] The intermediate storage tanks are at least three connected in parallel, specifically a first intermediate storage tank 3, a second intermediate storage tank 4, and a third intermediate storage tank 5 connected in parallel;

[0097] A two-way boron transfer pipeline 12 is provided between the intermediate storage tank and the refueling water tank 11;

[0098] The reactor water pool 8, component pool 9 and loading well 10 are respectively connected to the refueling water tank 11;

[0099] A detachable airlock door 20 is provided between the reactor water pool 8 and the component pool 9 .

[0100] like Figure 2 As shown, the bidirectional boron transfer pipeline 12 includes three branches:

[0101] The first branch ends at an intermediate storage tank and a refueling water tank 11;

[0102] The first branch is provided with a first valve 13, a second valve 14, a boron transfer pump 19, a third valve 16 and a fourth valve 18 in sequence;

[0103] One end of the second branch is connected between the first valve 13 and the second valve 14, and the other end is connected to the outlet of the boron transfer pump 19; a fifth valve 15 is provided on the second branch;

[0104] One end of the third branch is connected to the inlet of the boron transfer pump 19 , and the other end is connected between the third valve 16 and the fourth valve 18 ; a sixth valve 17 is provided on the third branch.

[0105] A method for recovering boric acid solution using the boric acid solution recovery system of a nuclear power plant is as follows: Figure 3 As shown, including:

[0106] Recovery of boric acid solution discharged from the reactor primary circuit 1 and recovery of boric acid solution in the refueling water tank 11;

[0107] The recovery of the boric acid solution discharged from the reactor primary loop 1 includes:

[0108] From the time when the concentration of the boric acid solution discharged from the reactor primary loop 1 was less than 2400 ppm during the reactor startup to the time when the concentration of the boric acid solution discharged from the reactor primary loop 1 reached 2400 ppm during the reactor shutdown, the concentration of the boric acid solution discharged from the reactor primary loop 1 was less than 2400 ppm.

[0109] The boric acid solution with a concentration of less than 2400 ppm discharged from the primary loop 1 of the above-mentioned reactor is collected in the first intermediate storage tank 3 through the front storage tank 2. The target boron concentration of the evaporator 6 is set to 2400 ppm. The boric acid solution with a concentration of less than 2400 ppm is evaporated and concentrated into a boric acid solution with a concentration of 2400 ppm through the evaporator 6 and stored in the boric acid solution storage tank 7. The volume of this part of the boric acid solution with a concentration of 2400 ppm is approximately 60 m³.

[0110] If the refueling water tank 11 does not need to be emptied for maintenance, the approximately 60 m³ of 2400 ppm boric acid solution in the boric acid solution storage tank 7 is transferred to the refueling water tank 11 .

[0111] If the refueling water tank 11 needs to be emptied for maintenance, after the emptying and maintenance of the refueling water tank 11 is completed, about 60m³ of 2400ppm concentration of boric acid solution in the boric acid solution storage tank 7 is transferred to the refueling water tank 11.

[0112] From the time the concentration of the boric acid solution discharged from the primary loop 1 of the reactor reached 2400 ppm during the reactor shutdown to the time the concentration of the boric acid solution discharged from the primary loop 1 of the reactor became less than 2400 ppm during the reactor startup, the concentration of the boric acid solution discharged from the primary loop 1 of the reactor was equal to 2400 ppm.

[0113] The boric acid solution with a concentration of 2400 ppm discharged from the primary loop 1 of the reactor is collected in the second intermediate storage tank 4 and the third intermediate storage tank 5 through the front storage tank 2. The volume of the boric acid solution with a concentration of 2400 ppm is about 100 m³.

[0114] If the refueling water tank 11 does not need to be emptied for maintenance, about 100 m³ of 2400 ppm boric acid solution in the second intermediate storage tank 4 and the third intermediate storage tank 5 is transferred to the refueling water tank 11 through the two-way boron transfer pipeline 12.

[0115] If the refueling water tank 11 needs to be emptied for maintenance, after the emptying and maintenance of the refueling water tank 11 is completed, about 100m³ of 2400ppm concentration of boric acid solution in the second intermediate storage tank 4 and the third intermediate storage tank 5 will be transferred to the refueling water tank 11 through the two-way boron transfer pipeline 12.

[0116] The operation method of the bidirectional boron transfer pipeline 12 is:

[0117] The first valve 13, the second valve 14, the third valve 16 and the fourth valve 18 are opened; the fifth valve 15 and the sixth valve 17 are closed, and the boron transfer pump 19 is started. The recovery of the boric acid solution in the refueling water tank 11 includes:

[0118] Before unloading the reactor, transfer 1470m³ of boric acid solution in the refueling water tank 11 to the reactor water pool 8 and component pool 9 until the reactor water pool 8 and component pool 9 are full;

[0119] After the reactor is unloaded, an airlock door 20 is installed between the reactor water pool 8 and the component pool 9. The 870m³ boric acid solution in the component pool 9 is not returned to the refueling water tank 11, and the 600m³ boric acid solution in the reactor water pool 8 is returned to the refueling water tank 11;

[0120] Drain the reactor primary circuit 1 to carry out maintenance on the reactor primary circuit 1 related equipment;

[0121] Before the refueling water tank 11 is overhauled, the 752m³ boric acid solution in the refueling water tank 11 is transferred to the second intermediate storage tank 4 and the third intermediate storage tank 5 through the two-way boron transfer pipeline 12;

[0122] The operation method of the bidirectional boron transfer pipeline 12 is:

[0123] The first valve 13, the fourth valve 18, the fifth valve 15 and the sixth valve 17 are opened; the second valve 14 and the third valve 16 are closed, and the boron transfer pump 19 is started;

[0124] Before the refueling water tank 11 is overhauled, the remaining 230m³ of boric acid solution in the refueling water tank 11 is transferred to the loading well 10. At this time, the refueling water tank 11 has been emptied and is ready for overhaul.

[0125] After the refueling water tank 11 is overhauled, the 752m³ boric acid solution in the second intermediate storage tank 4 and the third intermediate storage tank 5 is transferred back to the refueling water tank 11 through the two-way boron transfer pipeline 12;

[0126] The operation method of the bidirectional boron transfer pipeline 12 is:

[0127] The first valve 13 , the second valve 14 , the third valve 16 and the fourth valve 18 are opened; the fifth valve 15 and the sixth valve 17 are closed, and the boron transfer pump 19 is started.

[0128] After the refueling water tank 11 is overhauled, the 230m³ boric acid solution in the loading well 10 is returned to the refueling water tank 11.

[0129] Before loading the reactor, 600m³ of boric acid solution in the refueling water tank 11 is transferred to the reactor water pool 8, and the airlock door 20 between the reactor water pool 8 and the component pool 9 is removed.

[0130] After the reactor is loaded, 1470 m³ of boric acid solution in the reactor water pool 8 and component pool 9 is returned to the refueling water tank 11.

[0131] The boric acid solution recovery system and method for a nuclear power plant according to the present invention were compared with the original design of the nuclear power plant. The results are shown in Table 1.

[0132] Table 1 Comparison of the boric acid solution recovery system and method of the present invention and the original design of the nuclear power plant

[0133] As can be seen from Table 1, the present invention solves the problem that the boric acid solution recovery system originally designed for a nuclear power plant cannot recover the boric acid solution, pollutes the environment, and affects the overhaul period.

[0134] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0135] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A boric acid solution recovery system for a nuclear power plant, characterized in that: include: The front storage tank has one end connected to the reactor primary circuit, and the other end is connected in sequence to the intermediate storage tank, evaporator, boric acid storage tank and refueling water tank; There are at least three intermediate storage tanks connected in parallel; A two-way boron transfer pipeline is set between the intermediate storage tank and the refueling water tank; The reactor water pool, component pool and loading well are respectively connected to the refueling water tank.

2. The boric acid solution recovery system for a nuclear power plant according to claim 1, characterized in that: The bidirectional boron transfer pipeline includes three branches; The two ends of the first branch are the intermediate storage tank and the refueling water tank; The first branch is provided with a first valve, a second valve, a boron transfer pump, a third valve and a fourth valve in sequence; One end of the second branch is connected between the first valve and the second valve, and the other end is connected to the outlet of the boron transfer pump; a fifth valve is provided on the second branch; One end of the third branch is connected to the inlet end of the boron transfer pump, and the other end is connected between the third valve and the fourth valve; a sixth valve is arranged on the third branch.

3. The boric acid solution recovery system for a nuclear power plant according to claim 1, characterized in that: A detachable airlock door is installed between the reactor water pool and the component pool.

4. A method for recovering boric acid solution in a nuclear power plant, characterized in that: include: Recovery of boric acid solution discharged from the reactor primary circuit and recovery of boric acid solution in the refueling water tank; The recovery of the boric acid solution discharged from the primary loop of the reactor is specifically as follows: Determine the concentration of the boric acid solution discharged from the reactor's primary circuit. If it is less than 2400 ppm, concentrate the discharged boric acid solution to 2400 ppm in an evaporator and then store it in a boric acid storage tank until the refueling water tank is available. If the concentration of the boric acid solution discharged from the reactor primary circuit is equal to 2400 ppm, the discharged boric acid solution shall be stored in any two intermediate storage tanks of sufficient capacity until it is transferred to the refueling water tank after it becomes available; The recovery of boric acid solution in the refueling water tank is as follows: Before unloading, transfer part of the boric acid solution in the refueling water tank to the reactor water pool and component pool until the reactor water pool and component pool are full; After the reactor is unloaded, only the boric acid solution in the reactor pool is returned to the refueling tank; Before the refueling water tank is overhauled, part of the boric acid solution in the refueling water tank is transferred to any two intermediate storage tanks with sufficient capacity through a two-way boron transfer pipeline until the two intermediate storage tanks are full, and the remaining boric acid solution in the refueling water tank is transferred to the loading well; After the refueling water tank is overhauled, the boric acid solution in the intermediate storage tank is transferred back to the refueling water tank through the two-way boron transfer pipeline; Return the boric acid solution in the loading well to the refueling water tank; Before loading the reactor, a portion of the boric acid solution in the refueling tank is transferred to the reactor pool until the reactor pool is full; After the reactor is loaded, the boric acid solution in the reactor water pool and component pool is returned to the refueling tank.

5. The method for recovering boric acid solution in a nuclear power plant according to claim 4, characterized in that: The operating condition in which the concentration of the boric acid solution discharged from the reactor primary circuit is less than 2400 ppm includes: a period from when the concentration of the boric acid solution discharged from the reactor primary circuit is less than 2400 ppm during reactor startup to before the concentration of the boric acid solution discharged from the reactor primary circuit reaches 2400 ppm during reactor shutdown; The operating condition in which the concentration of the boric acid solution discharged from the primary loop of the reactor is equal to 2400 ppm includes: the period from when the concentration of the boric acid solution discharged from the primary loop of the reactor reaches 2400 ppm during reactor shutdown to when the concentration of the boric acid solution discharged from the primary loop of the reactor is less than 2400 ppm during reactor startup.

6. The method for recovering boric acid solution in a nuclear power plant according to claim 4, characterized in that: After the reactor is unloaded, an airlock door is installed between the reactor water pool and the component pool. The boric acid solution in the component pool is not returned to the refueling water tank, and only the boric acid solution in the reactor water pool is returned to the refueling water tank.

7. The method for recovering boric acid solution in a nuclear power plant according to claim 6, characterized in that: Before loading the reactor, a portion of the boric acid solution in the refueling water tank is transferred to the reactor water pool until the reactor water pool is full, and the airlock door between the reactor water pool and the component pool is removed.

8. The method for recovering boric acid solution in a nuclear power plant according to claim 4, characterized in that: When recovering the boric acid solution discharged from the primary circuit of the reactor; If the concentration of the boric acid solution discharged from the reactor primary circuit is equal to 2400 ppm, the discharged boric acid solution shall be stored in any two intermediate storage tanks with sufficient capacity; When the refueling water tank does not need to be repaired, the boric acid solution is directly transferred to the refueling water tank through the two-way boron transfer pipeline; When the refueling water tank needs to be repaired, the boric acid solution is transferred to the refueling water tank through the two-way boron transfer pipeline after the repair is completed.

9. The method for recovering boric acid solution in a nuclear power plant according to claim 8, characterized in that: When recovering the boric acid solution in the refueling water tank, before the refueling water tank is overhauled, a portion of the boric acid solution in the refueling water tank is transferred to any two intermediate storage tanks with sufficient capacity through a two-way boron transfer pipeline; The operation method of the two-way boron transfer pipeline is: The first valve, the fourth valve, the fifth valve and the sixth valve are opened; the second valve and the third valve are closed, and the boron transfer pump is started.

10. The method for recovering boric acid solution in a nuclear power plant according to claim 8, characterized in that: When the boric acid solution in the refueling water tank is recovered, after the refueling water tank is overhauled, the boric acid solution in the intermediate storage tank is returned to the refueling water tank through the two-way boron transfer pipeline. The operation method of the two-way boron transfer pipeline is as follows: The first valve, the second valve, the third valve and the fourth valve are opened; the fifth valve and the sixth valve are closed, and the boron transfer pump is started.

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