Boron replenishment method for the primary circuit of nuclear power plant

Abstract

This application relates to the technical field of boron and water supply systems, and provides a boron supply method for the primary circuit of a nuclear power plant. Before boron supply, the initial temperature of the primary circuit is T0, the initial liquid volume is M0, and the initial boric acid concentration is B0; after boron supply, the target temperature of the primary circuit is T 终 , the final liquid volume filling the primary circuit is M 终 , and the final boric acid concentration is B 终 ; the boron supply method includes the following steps: the first-stage supply, the primary circuit cools down from the initial temperature, and a high-concentration boric acid with a concentration of B 浓 is injected into the primary circuit to make the boric acid concentration in the solution in the primary circuit reach B 终 ; the second-stage supply, the primary circuit continues to cool down, and a dilute boric acid solution with the same concentration as B 终 is injected into the primary circuit until the primary circuit cools down to the target temperature and is fully loaded. The process does not require replacing the boron water in the original primary circuit, reduces the use of boric acid and water, improves economic benefits, and shortens the cooling time and boron supply time.

Description

Technical Field

[0001] The present application belongs to the technical field of boron and water replenishment systems for nuclear power plants, and more specifically, to a boron replenishment method for a primary circuit of a nuclear power plant. Background Art

[0002] A nuclear power plant is a facility that converts nuclear energy into electrical energy through appropriate devices. A nuclear power plant uses a nuclear reactor to replace the boiler of a thermal power plant. Nuclear fuel is burned in a special form in the nuclear reactor to generate heat, which converts nuclear energy into thermal energy to heat water and produce steam.

[0003] Among them, the pressurized water reactor nuclear power plant is mainly composed of the reactor, the reactor coolant system (referred to as the primary circuit), the steam and power conversion system (referred to as the secondary circuit), the circulating water system, the generator and the power transmission and distribution system and its auxiliary systems. The reactor core generates huge heat energy due to the fission of nuclear fuel. The water pumped into the core by the main pump is heated to 327 degrees and 155 atmospheres of high temperature and high pressure water. The high temperature and high pressure water flows through the heat transfer U-tube in the steam generator, and transfers the heat energy to the secondary circuit cooling water outside the U-tube through the tube wall. After releasing the heat, it is sent back to the core by the main pump for reheating and then enters the steam generator. In this way, the water circulates continuously in the closed primary circuit to provide a continuous supply of heat energy for the steam generator.

[0004] For the CPR1000 reactor, when the unit is preparing for refueling and overhaul, as the temperature and pressure of the primary circuit decrease, according to the technical specifications of the nuclear power plant, the primary circuit needs to be borated to the boric acid concentration required for cold shutdown to ensure the required subcriticality and ensure that the reactor is in a safe state. The primary circuit needs to be borated to 2300-2500ppm before refueling. During the cooling process, the volume of the solution in the primary circuit shrinks. At this time, the solution needs to be injected into the primary circuit to keep the primary circuit fully loaded, and after the cooling is completed, the boron content of the solution in the primary circuit reaches the target concentration.

[0005] However, the existing boron replenishment method is to first inject high-concentration boric acid into the primary circuit at high temperature to replace the low-concentration boric water in the original primary circuit, and then start cooling, and inject the target concentration of boric acid solution during the cooling process. This boron replenishment method is time-consuming, inefficient, and requires the replacement of the boric water in the original primary circuit, resulting in a waste of boric water. Summary of the invention

[0006] Based on this, the present application provides a boron replenishment method for the primary circuit of a nuclear power plant to solve the technical problems that the boronization method in the prior art is time-consuming, inefficient, and requires replacement of the boron water in the original primary circuit, resulting in waste of boron water.

[0007] To achieve the above purpose, the technical solution adopted in this application is:

[0008] A boron replenishment method for a primary circuit of a nuclear power plant, assuming that before the boron replenishment, the initial temperature of the primary circuit is T0, the initial liquid volume is M0, and the initial boric acid concentration is B0; after the boron replenishment, the target temperature of the primary circuit is T 终 , the final liquid volume filling one circuit is M 终 The final boric acid concentration is B 终 ;

[0009] The boron replenishment method comprises the following steps:

[0010] In the first stage of replenishment, the first circuit starts to cool down from the initial temperature and injects a concentration of B into the first circuit. 浓 The boric acid concentration in the first circuit reaches B 终 ;

[0011] In the second stage of replenishment, the first circuit is kept cool and the B 终 dilute boric acid solution of the same concentration until the first circuit is cooled to the target temperature, making the first circuit fully loaded;

[0012] Among them, T0>T 终 , M 终 >M0,B 浓 >B 终 >B0.

[0013] Optionally, the dilute boric acid solution is formed by simultaneously injecting and mixing high-concentration boric acid and water.

[0014] Alternatively, the amount of high concentration boric acid and water to be injected is calculated as follows:

[0015] When the temperature of a circuit drops from the initial temperature to the target temperature, the total amount of liquid that shrinks in the circuit is:

[0016] M 总 =M 终 -M0;

[0017] The total amount that needs to be injected is equal to the total amount of liquid contracted in one circuit.

[0018] Assume that the total amount of high-concentration boric acid injected in the first and second stage recharge is M 硼 The amount of water injected is M 水 ,

[0019] M 总 =M 硼 +M 水 ,

[0020] M 硼 =(M 终 *B 终 -M0*B0) / B 浓 ,

[0021] M 水 =M 总 -M 硼 =M 总 -(M 终 *B 终 -M0*B0) / B 浓 ,

[0022] The concentration of the dilute boric acid solution required for the second stage replenishment is B 终 The dilute boric acid solution is formed by injecting and mixing high-concentration boric acid and water respectively. The amount of high-concentration boric acid required for the second-stage replenishment is:

[0023] M 二阶 =B 终 *M 水 / (B 浓 -B 终 ),

[0024] Then, the amount of high concentration boric acid supplied in the first stage is:

[0025] M 一阶 =M 硼 -M 二阶 .

[0026] Optionally, the density of water and the amount of liquid required to fill a circuit at different temperatures are as follows:

[0027]

[0028] Optionally, the initial temperature T0 is 180°C-300°C; and / or the initial boric acid concentration is 1500-1900 ppm.

[0029] Optionally, the target temperature is 20°C-60°C.

[0030] Optionally, the final boric acid concentration B 终 It is 2300-2500ppm.

[0031] Optionally, B 浓 It is 7000-7700ppm.

[0032] Optionally, the cooling rate of one circuit is 25°C / hour-30°C / hour.

[0033] Optionally, in the first stage replenishment, the injection rate of high concentration boric acid is greater than 0 and less than or equal to 10 tons / hour.

[0034] Optionally, in the second stage replenishment, the injection rate of high concentration boric acid is 0-10 tons / hour, and the injection rate of water is 0-25.6 tons / hour.

[0035] The boron replenishment method for the primary circuit of a nuclear power plant provided in the present application replenishes boron to the primary circuit in two stages during the cooling process. In the first stage of replenishment, high-concentration boric acid is injected into the primary circuit to compensate for volume shrinkage, thereby achieving the purpose of increasing the boric acid concentration of the solution in the primary circuit; in the second stage of replenishment, a dilute boric acid solution is injected into the primary circuit, and the boric acid concentration of the dilute boric acid solution is consistent with the target boric acid concentration of the primary circuit; the process does not require replacement of the boric water in the original primary circuit, thereby reducing the use of boric acid and water, improving economic benefits, and shortening the cooling time, boron replenishment time, and the construction period of the unit overhaul. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

[0037] Figure 1 This is a schematic diagram of a replenishment system used in a boron replenishment method for a primary circuit of a nuclear power plant according to an embodiment of the present application.

[0038] Description of reference numerals:

[0039] Desalted water tank 11; desalted water pump 12; desalted water flow regulating valve 13; boric acid tank 21; boric acid pump 22; boric acid flow regulating valve 23. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0041] The embodiment of the present application provides a boron replenishment method for a primary circuit of a nuclear power plant. Assume that before the boron replenishment, the initial temperature of the primary circuit is T0, the initial liquid volume is M0, and the initial boric acid concentration is B0; after the boron replenishment, the target temperature of the primary circuit is T 终 , the final liquid volume filling one circuit is M 终 The final boric acid concentration is B 终 ;

[0042] The boron replenishment method comprises the following steps:

[0043] In the first stage of replenishment, the first circuit starts to cool down from the initial temperature and injects a concentration of B into the first circuit. 浓 The boric acid concentration in the first circuit reaches B 终 ;

[0044] In the second stage of replenishment, the first circuit is kept cool and the B 终 dilute boric acid solution of the same concentration until the first circuit is cooled to the target temperature, making the first circuit fully loaded;

[0045] Among them, T0>T终 , M 终 >M0,B 浓 >B 终 >B0.

[0046] The boron replenishment method for the primary circuit of a nuclear power plant provided in an embodiment of the present application replenishes boron to the primary circuit in two stages during the cooling process. In the first stage of replenishment, high-concentration boric acid is injected into the primary circuit to compensate for volume shrinkage, thereby achieving the purpose of increasing the boric acid concentration of the solution in the primary circuit; in the second stage of replenishment, a dilute boric acid solution is injected into the primary circuit, and the boric acid concentration of the dilute boric acid solution is consistent with the target boric acid concentration of the primary circuit; the process does not require replacement of the boric water in the original primary circuit, reduces the use of boric acid and water, improves economic benefits, and shortens the cooling time, boron replenishment time, and the construction period of the unit overhaul.

[0047] The primary circuit in the embodiment of the present application refers to the primary circuit of a nuclear power plant.

[0048] Boron replenishment in the embodiment of the present application refers to replenishing boric acid, mainly replenishing boric acid solution to a primary loop so that the boric acid solution in the primary loop reaches a preset concentration.

[0049] Optionally, the dilute boric acid solution is formed by injecting high-concentration boric acid and water at the same time. In the second-stage replenishment, a mixed liquid dilute boric acid solution of water and high-concentration boric acid is injected into the primary circuit, and the boric acid concentration of the dilute boric acid solution can be adjusted by adjusting the injection amount and flow rate of water and high-concentration boric acid to ensure that the boric acid concentration of the mixed liquid dilute boric acid solution after injection is consistent with that of the primary circuit, which can meet the needs of various boric acid concentrations and is flexible in operation.

[0050] In order to achieve the purpose of replenishing boron for the primary circuit, the nuclear power plant has designed a reactor boron and water replenishment system, which mainly consists of a boric acid replenishment part and a water replenishment part. Figure 1 The water supply part is mainly used to inject clean water into the primary circuit to dilute and reduce the concentration of boric acid in the primary circuit. The water supply part mainly comprises a desalted water tank 11, a desalted water pump 12, and a desalted water flow regulating valve 13 connected in sequence. The output end of the desalted water flow regulating valve 13 is connected to the primary circuit.

[0051] The boric acid supply part is mainly used to inject high-concentration boric acid into the primary circuit to increase the boric acid concentration of the primary circuit. It mainly consists of a boric acid tank 21, a boric acid pump 22, and a boric acid flow control valve 23 connected in sequence. The output end of the boric acid flow control valve 23 is connected to the primary circuit. The water supply part and the boric acid supply part can also be used at the same time. By setting the flow constants of the desalted water flow control valve 13 and the boric acid flow control valve 23, water and high-concentration boric acid are mixed in a certain proportion and injected into the primary circuit at the same time. The concentration of the injected boric solution is consistent with the boric acid concentration of the primary circuit, which is used to compensate for the loss of water in the primary circuit.

[0052] Alternatively, the amount of high concentration boric acid and water to be injected is calculated as follows:

[0053] The total amount of solution that needs to be injected from the initial temperature of a circuit to the target temperature is:

[0054] M 总 =M 终 -M0;

[0055] Assume that the total amount of high-concentration boric acid injected in the first and second stage recharge is M 硼 The amount of water injected is M 水 The total amount of solution required to be injected is equal to the sum of the amount of high-concentration boron water injected and the amount of water injected.

[0056] M 总 =M 硼 +M 水 ;

[0057] The amount of boron injected is equal to the difference between the final boron amount and the initial boron amount, so

[0058] M 硼 =(M 终 *B 终 -M0*B0) / B 浓 ,but

[0059] M 水 =M 总 -M 硼 =M 总 -(M 终 *B 终 -M0*B0) / B 浓 ,

[0060] The concentration of the dilute boric acid solution required for the second stage replenishment is B 终 The dilute boric acid solution is formed by injecting and mixing high-concentration boric acid and water respectively. The amount of high-concentration boric acid required for the second-stage replenishment is:

[0061] M 二阶 =B 终 *M 水 / (B 浓 -B 终 ),

[0062] Then, the amount of high concentration boric acid supplied in the first stage is:

[0063] M 一阶 =M 硼 -M 二阶 .

[0064] Among them, the initial temperature T0, the initial liquid volume M0, the initial boric acid concentration B0, the high concentration boric acid B 浓is the actual measured value, the target temperature T 终 、Final liquid volume M 终 , Final boric acid concentration B 终 is the preset value, the actual measured value and the preset value are both known values, then in the above calculation formula, M0, B0, B 浓 、M 终 , B 终 is a known value, M 总 、M 硼 、M 水 、M 一阶 、M 二阶 All can be calculated according to the formula.

[0065] Optionally, the density of water and the amount of liquid required to fill a circuit at different temperatures are as follows:

[0066]

[0067]

[0068] As the temperature decreases, the mass of the solution remains unchanged, but the volume shrinks and the density increases. As the volume of the solution shrinks, more solution will need to be added to fill one circuit. Therefore, when the temperature is lower, one circuit can load more solution.

[0069] Optionally, the initial temperature T0 is 180°C-300°C. In the boron replenishment method provided in the embodiment of the present application, when the temperature starts to drop from a higher temperature, high-concentration boric acid can be injected into the primary circuit to shorten the extra time consumed by cooling. Therefore, the initial temperature T0 is generally selected to be 180°C-300°C, and the more commonly used initial temperature T0 can be selected to be 280°C-295°C. When the initial temperature T0 is 180°C-300°C, the initial boric acid concentration of the solution in the primary circuit may be 1500-1900ppm.

[0070] Optionally, the target temperature is 20°C-60°C. The final cooling temperature of the primary circuit can be set to a suitable temperature according to the situation to meet the needs of overhaul. Generally, the cooling target temperature of the primary circuit is selected as 20°C-60°C, and the more commonly used target temperature is selected as 50°C-60°C.

[0071] Optionally, the final boric acid concentration B 终 The boric acid concentration is 2300-2500ppm, which can ensure the subcriticality of cold shutdown and keep the reactor in a safe state.

[0072] Optionally, B 浓 The concentration of boric acid in the solution in the first loop can reach the preset boric acid concentration by injecting the required amount of boric acid at a relatively low injection speed, which is beneficial for adjusting the coordination between the cooling speed and the injection speed.

[0073] Optionally, the cooling rate of a circuit is 25°C / hour-30°C / hour. It can be understood that if the cooling rate of a circuit is too fast, for example, the cooling rate is greater than 30°C / hour, the volume of the solution shrinks too fast, and the injection rate of high-concentration boric acid or dilute boric acid solution needs to be accelerated, which is not conducive to uniform stirring of the solution in the circuit; if the cooling rate of a circuit is too slow, for example, the cooling rate is less than 25°C / hour, the entire boron replenishment process will take a long time, which is not conducive to shortening the overhaul period of the unit; therefore, the cooling rate of a circuit is generally selected to be 25°C / hour-30°C / hour.

[0074] Optionally, in the first stage of replenishment, the injection rate of high concentration boric acid is greater than 0 and less than or equal to 10 tons / hour. The injection rate of high concentration boric acid is adjusted according to the cooling rate of the first circuit. The cooling rate directly affects the volume shrinkage rate of the solution in the first circuit. The cooling rate of the first circuit is generally selected as 25℃ / hour-30℃ / hour, and the injection rate of high concentration boric acid.

[0075] Optionally, in the second stage replenishment, the injection rate of high concentration boric acid is 0-10 tons / hour, and the injection rate of water is 0-25.6 tons / hour. According to the cooling rate of the first circuit and the preset final boric acid concentration of the first circuit, the injection rates of high concentration boric acid and water are adjusted so that the boric acid concentration after the mixture of the two is equal to the final boric acid concentration of the first circuit, and the injection amount of the two is coordinated with the cooling volume shrinkage of the first circuit. When in the calculation formula, M 总 =M 硼 When M 水 Equal to 0, the corresponding M 二阶 Equal to 0, that is, after the first-stage replenishment is completed, the solution in the first circuit can meet the preset requirements and there is no need for the second-stage replenishment. At this time, in the second-stage replenishment, the injection rate of high-concentration boric acid and water is 0.

[0076] The boron replenishment method for the primary circuit of a nuclear power plant provided in the present application shortens the cooling time and boron replenishment time of the primary circuit, while reducing the use of high-concentration boric acid and desalted water, thereby improving economic benefits.

[0077] The following uses a number of embodiments to illustrate the boron replenishment method and system for the primary circuit of a nuclear power plant, its products, and product performance.

[0078] The density of water and the amount of liquid required to fill a circuit at different temperatures are shown in the following table:

[0079]

[0080] Example 1

[0081] In this embodiment, the initial temperature T0 of the first loop is 290°C, the corresponding initial liquid volume M0 is 223.9 tons, the initial boric acid concentration B0 is 1700 ppm, and the boric acid concentration B0 of the high concentration boric acid is 1700 ppm. 浓 is 7350ppm, and the target temperature T for cooling the first circuit is set 终 At 50°C, the corresponding final liquid volume M 终 The final boric acid concentration is 297 tons. 终 It is 2400ppm.

[0082] Calculate the amount of high concentration boric acid and water that needs to be injected:

[0083] M 总 =M 终 -M0=297-223.9=73.1 tons,

[0084] Assume that the total amount of high-concentration boric acid injected in the first and second stage recharge is M 硼 The amount of water injected is M 水 ,

[0085] M 硼 =(M 终 *B 终 -M0*B0) / B 浓 =(297*2400-223.9*1700) / 7350=45.2 tons,

[0086] M 水 =M 总 -M 硼 =73.1-45.2=27.9 tons,

[0087] The concentration of the dilute boric acid solution required for the second stage replenishment is B 终 The dilute boric acid solution is formed by injecting and mixing high-concentration boric acid and water respectively. The amount of high-concentration boric acid required for the second-stage replenishment is:

[0088] M 二阶 =B 终 *M 水 / (B 浓 -B 终 )=2400*27.9 / (7350-2400)=13.5 tons,

[0089] The amount of high concentration boric acid supplied in the first stage is:

[0090] M 一阶 =M 硼 -M 二阶 =45.2-13.5=31.7 tons.

[0091] The boron replenishment method for the primary circuit of a nuclear power plant of this embodiment comprises the following steps:

[0092] In the first stage of replenishment, the primary circuit starts to cool down from the initial temperature at a cooling rate of 25°C / hour, and 31.7 tons of high-concentration boric acid with a concentration of 7350ppm is injected into the primary circuit at a rate of 5 tons / hour, so that the boric acid concentration of the solution in the primary circuit reaches 2400ppm;

[0093] In the second stage of replenishment, the first circuit is kept cooling, and 13.5 tons of high-concentration boric acid with a concentration of 7350ppm and 27.9 tons of water are injected into the first circuit. The injection rate of high-concentration boric acid is 1.92 tons / hour, and the injection rate of water is 4 tons / hour, until the first circuit is cooled to 50°C and the first circuit is fully loaded.

[0094] Example 2

[0095] In this embodiment, the initial temperature T0 of the first loop is 280°C, the corresponding initial liquid volume M0 is 229.2 tons, the initial boric acid concentration B0 is 1900 ppm, and the boric acid concentration B0 of the high concentration boric acid is 1900 ppm. 浓 The target temperature T for cooling the first circuit is set to 7000ppm. 终 At 60°C, the corresponding final liquid volume M 终 The final boric acid concentration is 295.5 tons. 终 It is 2350ppm.

[0096] Calculate the amount of high concentration boric acid and water that needs to be injected:

[0097] M 总 =M 终 -M0=295.5-229.2=66.3 tons,

[0098] Assume that the total amount of high-concentration boric acid injected in the first and second stage recharge is M 硼 The amount of water injected is M 水 ,

[0099] M 硼 =(M 终 *B 终 -M0*B0) / B 浓 =(295.5*2350-229.2*1900) / 7000=37.0 tons,

[0100] M 水 =M 总 -M 硼 =66.3-37.0=29.3 tons,

[0101] The concentration of the dilute boric acid solution required for the second stage replenishment is B 终 The dilute boric acid solution is formed by injecting and mixing high-concentration boric acid and water respectively. The amount of high-concentration boric acid required for the second-stage replenishment is:

[0102] M 二阶 =B 终 *M 水 / (B 浓 -B 终 )=2350*29.3 / (7000-2350)=14.8 tons,

[0103] The amount of high concentration boric acid supplied in the first stage is:

[0104] M 一阶 =M 硼 -M 二阶 =37.0-14.8=22.2 tons.

[0105] The boron replenishment method for the primary circuit of a nuclear power plant of this embodiment comprises the following steps:

[0106] In the first stage of replenishment, the primary circuit starts to cool down from 280°C at a rate of 30°C / hour, and 22.2 tons of high-concentration boric acid with a concentration of 7000ppm is injected into the primary circuit at a rate of 10 tons / hour, so that the boric acid concentration of the solution in the primary circuit reaches 2350ppm;

[0107] In the second stage of replenishment, the first circuit is kept cooling, and 14.8 tons of high-concentration boric acid with a concentration of 7000 ppm and 29.3 tons of water are injected into the first circuit. The injection rate of high-concentration boric acid is 10 tons / hour, and the injection rate of water is 20 tons / hour, until the first circuit is cooled to 60°C and the first circuit is fully loaded.

[0108] Example 3

[0109] In this embodiment, the initial temperature T0 of the first loop is 300°C, the corresponding initial liquid volume M0 is 217.9 tons, the initial boric acid concentration B0 is 1650ppm, and the boric acid concentration B0 of the high concentration boric acid is 1650ppm. 浓 The target temperature T for cooling the first circuit is set to 7500ppm. 终 At 40°C, the corresponding final liquid volume M 终 The final boric acid concentration is 298.2 tons. 终 It is 2500ppm.

[0110] Calculate the amount of high concentration boric acid and water that needs to be injected:

[0111] M 总 =M 终 -M0=298.2-217.9=80.3 tons,

[0112] Assume that the total amount of high-concentration boric acid injected in the first and second stage recharge is M 硼 The amount of water injected is M 水 ,

[0113] M 硼 =(M 终 *B 终 -M0*B0) / B 浓 =(298.2*2500-217.9*1650) / 7500=51.5 tons,

[0114] M 水 =M 总 -M 硼 =80.3-51.5=28.8 tons,

[0115] The concentration of the dilute boric acid solution required for the second stage replenishment is B 终 The dilute boric acid solution is formed by injecting and mixing high-concentration boric acid and water respectively. The amount of high-concentration boric acid required for the second-stage replenishment is:

[0116] M 二阶 =B 终 *M 水 / (B 浓 -B 终 )=2500*28.8 / (7500-2500)=14.4 tons,

[0117] The amount of high concentration boric acid supplied in the first stage is:

[0118] M 一阶 =M 硼 -M 二阶 =51.5-14.4=37.0 tons.

[0119] The boron replenishment method for the primary circuit of a nuclear power plant of this embodiment comprises the following steps:

[0120] In the first stage of replenishment, the primary circuit starts to cool down from the initial temperature at a cooling rate of 28°C / hour, and 37.0 tons of high-concentration boric acid with a concentration of 7500ppm is injected into the primary circuit at a rate of 7 tons / hour, so that the boric acid concentration of the solution in the primary circuit reaches 2500ppm;

[0121] In the second stage of replenishment, the first circuit is kept cooling, and 14.4 tons of high-concentration boric acid with a concentration of 7500ppm and 28.8 tons of water are injected into the first circuit. The injection rate of high-concentration boric acid is 5 tons / hour, and the injection rate of water is 10 tons / hour, until the first circuit is cooled to 40℃ and the first circuit is fully loaded.

[0122] Example 4

[0123] In this embodiment, the initial temperature T0 of the first loop is 290°C, the corresponding initial liquid volume M0 is 223.9 tons, the initial boric acid concentration B0 is 1600ppm, and the boric acid concentration B0 of the high concentration boric acid is 1600ppm. 浓is 7700ppm, and the target temperature T for cooling the first circuit is set 终 At 60°C, the corresponding final liquid volume M 终 The final boric acid concentration is 295.5 tons. 终 It is 2500ppm.

[0124] Calculate the amount of high concentration boric acid and water that needs to be injected:

[0125] M 总 =M 终 -M0=295.5-223.9=71.6 tons,

[0126] Assume that the total amount of high-concentration boric acid injected in the first and second stage recharge is M 硼 The amount of water injected is M 水 ,

[0127] M 硼 =(M 终 *B 终 -M0*B0) / B 浓 =(295.5*2500-223.9*1600) / 7700=49.4 tons,

[0128] M 水 =M 总 -M 硼 =71.6-49.4=22.2 tons,

[0129] The concentration of the dilute boric acid solution required for the second stage replenishment is B 终 The dilute boric acid solution is formed by injecting and mixing high-concentration boric acid and water respectively. The amount of high-concentration boric acid required for the second-stage replenishment is:

[0130] M 二阶 =B 终 *M 水 / (B 浓 -B 终 )=2500*22.2 / (7700-2500)=10.7 tons,

[0131] The amount of high concentration boric acid supplied in the first stage is:

[0132] M 一阶 =M 硼 -M 二阶 =49.4-10.7=38.8 tons.

[0133] The boron replenishment method for the primary circuit of a nuclear power plant of this embodiment comprises the following steps:

[0134] In the first stage of replenishment, the primary circuit starts to cool down from the initial temperature at a cooling rate of 25°C / hour, and 38.8 tons of high-concentration boric acid with a concentration of 7700ppm is injected into the primary circuit at a rate of 2 tons / hour, so that the boric acid concentration of the solution in the primary circuit reaches 2500ppm;

[0135] In the second stage of replenishment, the first circuit is kept cooling, and 10.7 tons of high-concentration boric acid with a concentration of 7700ppm and 22.2 tons of water are injected into the first circuit. The injection rate of high-concentration boric acid is 2.9 tons / hour, and the injection rate of water is 6 tons / hour, until the first circuit is cooled to 60℃ and the first circuit is fully loaded.

[0136] The boron replenishment method for the primary circuit of a nuclear power plant provided in the embodiment of the present application replenishes boron from the cooling down from the highest temperature, without replacing the boron water in the original primary circuit, thereby reducing the waste of boron water and the boration time, and improving economic benefits and work efficiency.

[0137] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A boron replenishment method for a primary circuit of a nuclear power plant, characterized in that: Assume that before boron replenishment, the initial temperature of the first circuit is T0, the initial liquid volume is M0, and the initial boric acid concentration is B0; after boron replenishment, the target temperature of the first circuit is T 终 , the final liquid volume filling the first circuit is M 终 The final boric acid concentration is B 终 ; The boron replenishment method comprises the following steps: In the first stage of replenishment, the first loop starts cooling from the initial temperature and injects a concentration of B into the first loop. 浓 The boric acid concentration of the solution in the first loop reaches the B 终 ; In the second stage of replenishment, the first circuit maintains the cooling treatment and injects the B 终 A dilute boric acid solution of the same concentration is added until the primary circuit is cooled to the target temperature, so that the primary circuit is fully loaded; wherein the dilute boric acid solution is formed by injecting and mixing the high concentration boric acid and water at the same time, and the boric acid concentration of the dilute boric acid solution is adjusted by adjusting the injection amount and flow rate of water and the high concentration boric acid; Among them, T0>T 终 , M 终 >M0,B 浓 >B 终 >B0; The calculation method for the amount of high concentration boric acid and water to be injected is: The total amount of solution required to be injected from the initial temperature of the first circuit to the target temperature is: M 总 =M 终 -M0; Assume that the total amount of high concentration boric acid injected by the first and second stage replenishment is M 硼 The amount of water injected is M 水 , M 总 =M 硼 +M 水 , M 硼 =(M 终 *B 终 -M0*B0) / B 浓 , M 水 =M 总 -M 硼 =M 总 -(M 终 *B 终 -M0*B0) / B 浓 , The concentration of the dilute boric acid solution required for the second stage replenishment is B 终 The dilute boric acid solution is formed by injecting and mixing the high concentration boric acid and water respectively. The amount of high concentration boric acid required for the second stage replenishment is: M 二阶 =B 终 *M 水 / (B 浓 -B 终 ), Then, the amount of high concentration boric acid supplied in the first stage is: M 一阶 =M 硼 -M 二阶 。 2. The boron replenishment method for the primary circuit of a nuclear power plant according to claim 1, characterized in that: The density of water and the amount of liquid required to fill the primary circuit at different temperatures are as follows: 。 3. The boron replenishment method for the primary circuit of a nuclear power plant according to claim 1 or 2, characterized in that: The initial temperature T0 is 180°C-300°C; and / or the initial boric acid concentration is 1500-1900 ppm.

4. The boron replenishment method for the primary circuit of a nuclear power plant according to claim 1 or 2, characterized in that: The target temperature is 20°C-60°C.

5. The boron replenishment method for the primary circuit of a nuclear power plant according to claim 1 or 2, characterized in that: The final boric acid concentration B 终 2300-2500ppm; and / or, the B 浓 It is 7000-7700ppm.

6. The boron replenishment method for the primary circuit of a nuclear power plant according to claim 1 or 2, characterized in that: The cooling rate of the cooling treatment is 25°C / hour-30°C / hour.

7. The boron replenishment method for the primary circuit of a nuclear power plant according to claim 1 or 2, characterized in that: The injection rate of the high concentration boric acid is greater than 0 and less than or equal to 10 tons / hour.

8. The boron replenishment method for the primary circuit of a nuclear power plant according to claim 2, characterized in that: In the second stage replenishment, the injection rate of the high concentration boric acid is 0-10 tons / hour, and the injection rate of the water is 0-25.6 tons / hour.

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