Boron concentration control method of nuclear power unit cooling loop and storage medium

Abstract

The invention relates to the technical field of nuclear power, in particular to a boron concentration control method of a nuclear power unit cooling loop and a storage medium. The boron concentration control method for the nuclear power unit cooling loop comprises the steps that the total volume of a coolant in the cooling loop at the full power temperature is obtained; the volume difference between the liquid volume and the total volume of the coolant at the preset temperature is obtained, and the shrinkage amount is obtained; according to the abundance and the total volume of the boron 10 in the enriched boron solution, the required material changing boron concentration is calculated; designing the effective volume and the stored boric acid concentration of the boric acid storage tank according to the shrinkage amount, the total volume and the reloading boron concentration; storing a boric acid solution prepared from the enriched boron solution according to the concentration of the stored boric acid in a boric acid storage tank; and the boric acid solution is injected into the cooling loop, so that the coolant reaches the reloading boron concentration before the preset temperature. According to the method, the concentration of boron in the cooling loop is controlled by adopting enriched boron, so that the volume of the required boric acid solution can be reduced while the cooling loop is rapidly boronized.

Description

Technical Field

[0001] This invention relates to the field of nuclear power technology, and in particular to a method for controlling boron concentration in the cooling circuit of a nuclear power unit and a storage medium therein. Background Technology

[0002] Under normal circumstances, nuclear power units use natural boron to borate the primary circuit, resulting in a boron concentration of 2300-2500 mg / kg during refueling, which has the following disadvantages.

[0003] The total volume of the primary circuit of a nuclear power unit is approximately 300 m³. 3 At 310℃, the first-loop coolant mass is 202 tons, and at 180℃, it is 266.6 tons. During normal operation, the unit needs 7350 mg / kg of boric acid solution to compensate for coolant volume shrinkage when cooling from 310℃ to 180℃, which means borizing 266.6 - 202 = 64.6 tons. If the initial conditions are all clean water, the boron concentration in the first loop after borization is approximately 1780 mg / kg. In reality, the boron concentration at the end of the unit's lifespan is approximately 10-20 mg / kg, and after borization, the boron concentration in the first loop is approximately 2000 mg / kg. If the boron concentration needs to be reached before reaching 180℃ for refueling, additional borization is required, which will lead to low-boron water entering the TEP system, resulting in some waste of boric acid. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for controlling boron concentration in the cooling circuit of a nuclear power unit and a storage medium.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for controlling boron concentration in the cooling circuit of a nuclear power unit, comprising the following steps:

[0006] Obtain the total volume of coolant in the cooling circuit at full power temperature;

[0007] The volume difference between the liquid volume of the coolant at a preset temperature and the total volume is obtained to determine the shrinkage amount of the coolant.

[0008] The required boron concentration for material replacement is calculated based on the boron abundance in the boron-enriched solution and the total volume.

[0009] The effective volume and storage boric acid concentration of the boric acid storage tank in the boric acid injection system are designed based on the shrinkage amount, the total volume, and the boron concentration of the replacement material; and a boric acid solution prepared by the enriched boron solution according to the storage boric acid concentration is stored in the boric acid storage tank according to the effective volume.

[0010] The boric acid solution is injected into the cooling circuit to borate the coolant therein, so that the coolant reaches the boron concentration required for material replacement before the preset temperature.

[0011] Preferably, the step of injecting the boric acid solution into the cooling circuit to borate the coolant therein, so that the coolant reaches the replacement boron concentration before the preset temperature, includes:

[0012] The boric acid injection system mixes the boric acid solution with water in a preset ratio to obtain a replenishing borylation solution;

[0013] The replenishing boron solution is injected into the cooling circuit at a preset rate so that the coolant reaches the replacement boron concentration before the preset temperature.

[0014] Preferably, the step of injecting the replenishing borylation solution into the cooling circuit at a preset rate, so that the coolant reaches the replacement boron concentration before the preset temperature, includes:

[0015] Before reaching the preset temperature, it is detected whether the concentration of cooling boron in the coolant in the cooling circuit reaches the replacement boron concentration;

[0016] If the cooling boron concentration does not reach the replacement boron concentration, the temperature in the cooling circuit is maintained at the preset temperature until the cooling boron concentration reaches the replacement boron concentration.

[0017] Preferably, the boric acid injection system is equipped with at least two boric acid storage tanks; the effective volume of a single boric acid storage tank is greater than or equal to the volume of the boric acid solution.

[0018] Preferably, the step of designing the effective volume of the boric acid storage tank and the storage boric acid concentration based on the shrinkage amount, the total volume, and the boron concentration for material replacement includes:

[0019] The volume of the boric acid solution is calculated based on the shrinkage, the total volume, and the boron concentration of the replacement material.

[0020] The effective volume and the storage boric acid concentration are designed based on the volume of the boric acid solution.

[0021] Preferably, the preset temperature includes 180°C; the boron 10 abundance in the enriched boron solution is greater than or equal to 35%.

[0022] Preferably, the boron recovery system of the nuclear power unit uses boron enrichment technology to produce boron after recovering the coolant.

[0023] Preferably, the source range of the nuclear power unit adopts a three-channel design.

[0024] Preferably, it further includes:

[0025] The steam in the voltage regulator in the cooling circuit is eliminated using a coolant with a concentration equal to that of the boron used for replacement.

[0026] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the boron concentration control method for the cooling circuit of a nuclear power unit as described in any of the above claims.

[0027] The implementation of this invention has the following beneficial effects:

[0028] This invention employs boron enrichment to control the boron concentration in the cooling circuit. While rapidly borizing the cooling circuit, it also reduces the volume of boric acid solution required. This enables the cooling circuit to be boronized to the concentration required for refueling shutdown before RIS / RHR connection. Subsequently, automatic replenishment via REA compensates for coolant contraction in the cooling circuit, improving unit safety and economy. Attached Figure Description

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0030] Figure 1 This is a flowchart of a boron concentration control method for a nuclear power unit cooling circuit in one embodiment. Detailed Implementation

[0031] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0033] This invention provides a method for controlling boron concentration in the cooling circuit of a nuclear power unit. For example... Figure 1 As shown, the boron concentration control method for the cooling circuit includes the following steps:

[0034] Obtain the total volume of coolant in the cooling circuit at full power temperature.

[0035] In some scenarios, the total volume is the same as the volume of the cooling circuit.

[0036] The volume difference between the liquid volume and the total volume of the coolant at a preset temperature is obtained to determine the amount of coolant shrinkage.

[0037] Understandably, at full power temperature, the mass of the coolant equal to its total volume is G1; the volume of the coolant with mass G1 at the preset temperature is its liquid volume. The volume difference is the amount of volume contraction of the coolant when it drops from full power temperature to the preset temperature.

[0038] The required boron concentration for replacement is calculated based on the boron abundance (10) in the enriched boron solution and the total volume.

[0039] After reactor shutdown, to ensure sufficient subcriticality and prevent recriticality due to accidents such as core overcooling or accidental dilution, boronization of the primary coolant is necessary. Boron-10 absorbs neutrons, therefore, the boron-10 content in the coolant during refueling must be controlled. Different boron-10 abundances result in different boron-10 contents at the same concentration; therefore, the boron-10 content can be ensured by considering the boron-10 abundance and total volume, further determining the boron concentration for refueling.

[0040] Furthermore, the use of boron-enriched solutions can significantly reduce the overall amount of boric acid used, effectively avoiding blockages or corrosion in the cooling system caused by boric acid crystallization, thus improving operational safety; at the same time, it reduces equipment wear and maintenance costs, extends service life, and brings economic benefits.

[0041] The effective volume and storage boric acid concentration of the boric acid storage tank in the boric acid injection system are designed based on the shrinkage, total volume, and boron concentration of the replacement material; and the boric acid solution prepared by the enriched boron solution according to the storage boric acid concentration is stored in the boric acid storage tank according to the effective volume.

[0042] Specifically, the effective volume must be greater than the shrinkage; the stored boric acid concentration must be less than the boric acid saturation concentration to prevent boric acid crystallization due to prolonged stasis or temperature drops. In some scenarios, the stored boric acid concentration is less than 2000 ppm.

[0043] Boric acid solution is injected into the cooling circuit to borate the coolant, so that the coolant reaches the boron concentration required for material replacement before reaching the preset temperature.

[0044] This invention employs boron enrichment to control the boron concentration in the cooling circuit, enabling rapid boronization of the cooling circuit to reach the refueling boron concentration before the preset temperature. Simultaneously, using boron enrichment for boronization reduces the required volume of boric acid solution, ensuring the shrinkage exceeds the required volume. This allows the cooling circuit to be boronized to the refueling shutdown boron concentration before RIS / RHR connection, after which automatic replenishment via REA can compensate for coolant shrinkage, improving unit safety and economy. Specifically, RIS stands for Recycled Heat Injection System, and RHR is the Residual Heat Removal System. This embodiment utilizes most of the equipment from the RIS low-pressure Recycled Heat Injection System to implement the RHR function.

[0045] In some embodiments, the cooling loop is the primary loop of a nuclear power unit. The amount of boric acid replenishment is the amount of boric acid solution prepared according to the stored boric acid concentration, required to borate the coolant to the refueling boron concentration at a preset temperature. In some scenarios, the effective volume should be greater than the boric acid replenishment amount. In some scenarios, the boric acid replenishment amount is calculated using the total volume, the refueling boron concentration, and the boron concentration in the coolant. In some scenarios, the boron concentration in the coolant is assumed to be 0, and the boric acid replenishment amount is calculated using the total volume and the refueling boron concentration.

[0046] In some feasible embodiments, the boric acid solution is mixed with the coolant in a preset ratio and then injected into the cooling circuit.

[0047] In some feasible embodiments, the coolant is water. Further, the coolant may be demineralized water.

[0048] In one executable embodiment, a boric acid solution is injected into a cooling circuit to borate the coolant therein, so that the coolant reaches a replacement boron concentration before reaching a preset temperature, including:

[0049] The boric acid injection system mixes boric acid solution with water in a preset ratio to obtain a replenishing borate solution.

[0050] Specifically, the difference between the volume of the boric acid solution prepared according to the stored boric acid concentration required for the coolant to reach the required boron concentration for refueling at a preset temperature in the cooling circuit and the shrinkage volume is obtained. A preset ratio is set based on this difference.

[0051] The replenishment boron solution is injected into the cooling circuit at a preset rate so that the coolant reaches the boron concentration required for material replacement before reaching the preset temperature.

[0052] In some feasible embodiments, the preset rate is calculated based on the coolant's contraction rate.

[0053] In some feasible embodiments, if the contraction rate is greater than a preset rate, coolant is added based on the rate difference between the two.

[0054] In some feasible embodiments, the boric acid injection system includes an REA boric acid circuit and a demineralized water circuit. Based on the cooling rate of the cooling circuit, the shrinkage rate of the coolant volume in the cooling circuit is calculated, and replenishment is made through the REA boric acid circuit and the demineralized water circuit. If the rate of boric acid solution injection through the REA boric acid circuit can compensate for the shrinkage rate during cooling, boration is performed only through the REA boric acid circuit; if the REA boric acid circuit cannot fully compensate, the demineralized water circuit is simultaneously activated for compensation.

[0055] In some feasible embodiments, the primary loop is cooled at a rate of 28°C / hour. The shrinkage rate of the primary loop volume is calculated and replenished through the REA boric acid circuit and the demineralized water circuit. If the boric acid injection rate of the REA boric acid circuit can compensate for the shrinkage rate of the primary loop during cooling, boration is performed (7000-7700 ppm boric acid solution, maximum replenishment rate 16 m / h). If the boric acid circuit cannot fully compensate, the demineralized water circuit is simultaneously activated for compensation. During the process, the boron meter reading is monitored to prevent the boron concentration in the primary loop from exceeding 1400 ppm.

[0056] In one executable embodiment, the replenishment of borylation solution is injected into the cooling circuit at a preset rate so that the coolant reaches the replacement boron concentration before a preset temperature, including:

[0057] Before reaching the preset temperature, check whether the concentration of cooling boron in the coolant in the cooling circuit reaches the replacement boron concentration.

[0058] If the cooling boron concentration does not reach the replacement boron concentration, the temperature in the cooling circuit will be maintained at the preset temperature until the cooling boron concentration reaches the replacement boron concentration.

[0059] In one feasible embodiment, the boric acid injection system is equipped with at least two boric acid storage tanks; the effective volume of a single boric acid storage tank is greater than or equal to the volume of the boric acid solution.

[0060] When a single boric acid storage tank fails, the backup boric acid storage tank immediately takes over, transforming the unacceptable risk of downtime into a controllable switching operation, ensuring that the cooling process is continuous, compliant, and maintainable.

[0061] In one executable embodiment, the effective volume and storage boric acid concentration of the boric acid storage tank are designed based on the shrinkage amount, total volume, and boron concentration during material replacement, including:

[0062] The volume of the boric acid solution is calculated based on the shrinkage, total volume, and boron concentration during material replacement.

[0063] Specifically, the volume of the boric acid solution should be less than the amount of shrinkage.

[0064] The effective volume and storage concentration of boric acid are designed based on the volume of the boric acid solution.

[0065] Specifically, storing boric acid at a concentration lower than that used for boric acid crystallization can prevent crystal precipitation and deposition, ensuring unobstructed pipelines, accurate metering, and eliminating the need for additional heating and insulation, thereby reducing maintenance frequency and operating costs.

[0066] In one executable embodiment, the preset temperature includes 180°C; the boron 10 abundance in the enriched boron solution is greater than or equal to 35%.

[0067] Specifically, 180℃ is the optimal temperature for the primary loop to connect to the RHR (Residual Heat Recovery) system (core residual heat removal system). 180℃ corresponds to a pressure of 3.0 MPa, ensuring the coolant is far from its boiling point (234℃), preventing flashing and pump cavitation. Simultaneously, connecting to the medium-to-high temperature range reduces the risk of thermal shock, protects piping equipment, and is fully compatible with the main system's depressurization shutdown conditions and the RHR's pressure-bearing design (≤3.0 MPa). Setting the preset temperature to 180℃ also improves heat recovery efficiency, reduces heat loss, further reduces the risk of cavitation, and enhances system stability.

[0068] In one feasible embodiment, the boron recovery system of a nuclear power unit uses boron enrichment technology to produce boron after recovering the coolant.

[0069] In one feasible embodiment, the source range of the nuclear power unit adopts a three-channel design.

[0070] The source range adopts a three-channel setting, which can still meet the technical specifications even when a single source range channel fails. It will not isolate the dilution source, ensure the integrity of the REA system's automatic replenishment function, and improve the stability of the automatic replenishment function.

[0071] In one feasible embodiment, a coolant with a concentration equal to that of the replacement boron is used to eliminate steam in the regulator in the cooling circuit.

[0072] A coolant with a temperature significantly lower than the saturation temperature under the current pressure and a concentration equal to that of the boron used for material replacement is continuously injected into the steam space of the pressure regulator to rapidly condense the steam in the pressure regulator.

[0073] In one feasible embodiment, the boron concentration for replacement is 1300-1400 ppm. The preset temperature is 180°C.

[0074] Based on the initial calculation of the boric acid required to borate the primary circuit to 1300-1400 ppm when the primary circuit reaches 180℃ (injection is completed when the primary circuit temperature reaches approximately 180℃).

[0075] Calculate the replenishment amount (contraction amount) of the primary coolant circuit based on the primary circuit's temperature drop rate of 28 degrees / hour.

[0076] Determine whether the maximum output of the REA boric acid circuit meets the replenishment requirement.

[0077] If the maximum output meets the replenishment requirement, the boric acid injection system calculates the replenishment of borate solution based on the template concentration, boron abundance, and boron concentration in the primary loop.

[0078] The boric acid injection system injects replenishing borate solution into the primary loop. The boron concentration in the primary loop is measured before the temperature drops to 180°C to determine if the boron concentration has reached the required level for material replacement.

[0079] If the desired temperature is not reached, continue to adjust the RHR cooling circuit (the RHR system inlet temperature is around 172°C, and after 3 hours, the boron concentration in the primary circuit can be adjusted to 1300-1400 ppm).

[0080] After the primary loop concentration reaches the refueling boron concentration, the RHR cooling loop and the primary loop are connected. Subsequently, the primary loop cooling continues to contract, while the primary loop pressurizer performs steam extinguishing operation to eliminate the steam in the pressurizer and make it a water substance (the steam extinguishing chamber requires water, and the boron concentration of this water must be 1300-1400ppm). The boron water output from the boric acid injection system is set to the shutdown boron concentration to supply water to the primary loop.

[0081] After reaching 180℃, the boric acid injection system uses automatic replenishment, setting the replenished boric acid concentration between 1300-1400 ppm, consistent with the boron concentration in the primary loop. The water level in the RCV system's capacity control tank is maintained at 1.7 to 1.8 meters. If it falls below 1.7 meters, it indicates that the primary loop medium is contracting or that the primary loop is using water, in which case automatic replenishment to the REA system is initiated. Automatic replenishment stops when the RCV capacity control tank reaches 1.8 meters.

[0082] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the boron concentration control method for the cooling circuit of a nuclear power unit as described above.

[0083] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the boron concentration control method for the cooling circuit of a nuclear power unit as described above.

[0084] The above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method for controlling boron concentration in the cooling circuit of a nuclear power unit, characterized in that, Includes the following steps: Obtain the total volume of coolant in the cooling circuit at full power temperature; The volume difference between the liquid volume of the coolant at a preset temperature and the total volume is obtained to determine the shrinkage amount of the coolant. The required boron concentration for material replacement is calculated based on the boron abundance in the boron-enriched solution and the total volume. The effective volume and storage boric acid concentration of the boric acid storage tank in the boric acid injection system are designed based on the shrinkage amount, the total volume, and the boron concentration of the replacement material; and a boric acid solution prepared by the enriched boron solution according to the storage boric acid concentration is stored in the boric acid storage tank according to the effective volume. The boric acid solution is injected into the cooling circuit to borate the coolant therein, so that the coolant reaches the boron concentration required for material replacement before the preset temperature.

2. The boron concentration control method according to claim 1, characterized in that, The step of injecting the boric acid solution into the cooling circuit to borate the coolant therein, so that the coolant reaches the boron concentration required for material replacement before the preset temperature, includes: The boric acid injection system mixes the boric acid solution with water in a preset ratio to obtain a replenishing borylation solution; The replenishing boron solution is injected into the cooling circuit at a preset rate so that the coolant reaches the replacement boron concentration before the preset temperature.

3. The boron concentration control method according to claim 2, characterized in that, The step of injecting the replenishing boron solution into the cooling circuit at a preset rate, so that the coolant reaches the replacement boron concentration before the preset temperature, includes: Before reaching the preset temperature, it is detected whether the concentration of cooling boron in the coolant in the cooling circuit reaches the replacement boron concentration; If the cooling boron concentration does not reach the replacement boron concentration, the temperature in the cooling circuit is maintained at the preset temperature until the cooling boron concentration reaches the replacement boron concentration.

4. The boron concentration control method according to claim 2, characterized in that, The boric acid injection system is equipped with at least two boric acid storage tanks; the effective volume of a single boric acid storage tank is greater than or equal to the volume of the boric acid solution.

5. The boron concentration control method according to claim 1, characterized in that, The design of the effective volume and storage boric acid concentration of the boric acid storage tank based on the shrinkage amount, the total volume, and the boron concentration for material replacement includes: The volume of the boric acid solution is calculated based on the shrinkage, the total volume, and the boron concentration of the replacement material. The effective volume and the storage boric acid concentration are designed based on the volume of the boric acid solution.

6. The boron concentration control method according to claim 1, characterized in that, The preset temperature includes 180℃; the boron 10 abundance in the enriched boron solution is greater than or equal to 35%.

7. The boron concentration control method according to claim 1, characterized in that, The boron recovery system of a nuclear power unit uses boron enrichment technology to produce boron after recovering the coolant.

8. The boron concentration control method according to claim 1, characterized in that, The source range of the nuclear power unit adopts a three-channel design.

9. The boron concentration control method according to claim 1, characterized in that, Also includes: The steam in the voltage regulator in the cooling circuit is eliminated using a coolant with a concentration equal to that of the boron used for replacement.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the boron concentration control method for the cooling circuit of a nuclear power unit as described in any one of claims 1-9.

Images