Method for calculating leakage rate from primary side to secondary side of steam generator

Abstract

The invention provides a method for calculating a leakage rate from a primary side to a secondary side of a steam generator. The calculation method comprises the steps that boron concentration data in water contained in the primary side of a steam generator, boron concentration data in water contained in the secondary side of the steam generator and boron concentration data in a steam generator blowdown system, a steam generator water supply system and a main steam system are utilized; and calculating the leakage rate from the primary side to the secondary side of the steam generator. According to the calculation method, the problem that the main steam flow is low and cannot be read through an instrument during the hot test is successfully solved, accurate calculation of the leakage rate from the primary side to the secondary side of the steam generator is achieved, and the method can be widely applied to leakage rate calculation of the steam generator in a nuclear power unit.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear power units, and in particular to a method for calculating the leakage rate from the primary side to the secondary side of a steam generator. Background Art

[0002] In the NOT / NOP platform (292℃, 15.4MPa) of the hot test phase of the CAP1400 nuclear power unit, it is necessary to verify whether the initial identifiable leakage rate and unidentifiable leakage rate of the primary RCS reactor coolant system meet the supervision requirements of the technical specifications. As a key indicator of the identifiable leakage rate of the primary circuit, the leakage rate from the primary side to the secondary side of the steam generator requires a simple and reliable calculation method to accurately detect the leakage rate from the primary side to the secondary side of the steam generator and verify that it meets the design requirements, which can ensure that the radioactive substances in the primary circuit will not diffuse to the secondary circuit through the steam generator heat transfer tubes.

[0003] CN111680257A discloses a method for calculating the leakage rate of a steam generator during a hot test of a nuclear power plant, comprising the steps of determining preconditions, sampling, analyzing samples and calculating the leakage rate of the steam generator; the calculation method can select different calculation formulas according to the different duration of the steam generator primary-to-secondary leakage rate test during the hot functional test of the nuclear power plant and the different states of the unit, thereby increasing the scope of application of the calculation method and further ensuring the accuracy of the calculation results of the steam generator leakage rate during the hot functional test of the nuclear power plant. However, the calculation method cannot accurately calculate the leakage rate from the primary side to the secondary side of the steam generator.

[0004] CN111540490A discloses a method for monitoring the leakage position of a steam generator of a pressurized water reactor nuclear power unit, and obtains the time Thot, Tbend, and Tcold of the transmission and steam diffusion of 16N and 19O coolants leaking at the hot end inlet, bend area, and cold end outlet of the heat transfer tube of the steam generator; calculates the concentration ratio of 16N and 19O when three typical leakage points leak; analyzes the γ-rays of the characteristic energy of 16N and 19O through a 16N radiation monitor arranged beside the main steam pipeline, measures the concentration of 16N and 19O respectively, and obtains the ratio; compares the above measured ratio with the theoretical ratio, and determines that the leakage position is the position corresponding to the theoretical ratio. This method can locate the leakage point of the heat transfer tube of the steam generator, improve the measurement accuracy of the steam generator leakage rate monitoring, and provide necessary information for the maintenance preparation of the heat transfer tube leakage.

[0005] CN115132389A discloses a method, device, equipment and storage medium for predicting seawater leakage of a condenser in a nuclear power plant. The method constructs a condenser seawater leakage monitoring model, inputs the real-time collected nuclear power plant condenser leakage prediction data into the model, and outputs the prediction result of the condenser seawater leakage of the nuclear power plant. Through the present invention, the condenser leakage of the nuclear power plant can be monitored, alarmed and intelligently calculated and judged, and intelligent technical support can be provided for the nuclear power plant to monitor and judge the condenser leakage, and the condenser seawater leakage can be detected at the first time and corrective actions can be taken to avoid impurities from entering the steam generator, and avoid the operation risk and economic loss caused by the power reduction or even shutdown of the nuclear power plant due to the condenser leakage.

[0006] The above method also has the problems of requiring more detection instruments to be matched, the calculation model is more complicated and it is impossible to accurately calculate the leakage rate from the primary side to the secondary side of the steam generator. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for calculating the leakage rate from the primary side to the secondary side of a steam generator, by analyzing and calculating the boron concentration data in the water contained in the primary side of the steam generator, the boron concentration data in the water contained in the secondary side of the steam generator, and the boron concentration in the steam generator sewage system, the steam generator water supply system and the main steam system, the leakage rate from the primary side to the secondary side of the steam generator can be obtained. The calculation method of the present invention successfully solves the problem that the main steam flow rate is low during the hot test and cannot be read by the instrument, and realizes the accurate calculation of the leakage rate from the primary side to the secondary side of the steam generator.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for calculating the leakage rate from the primary side to the secondary side of a steam generator. The calculation method comprises: using boron concentration data in water contained in the primary side of the steam generator, boron concentration data in water contained in the secondary side of the steam generator, and boron concentration data in a steam generator sewage system, a steam generator water supply system, and a main steam system to calculate the leakage rate from the primary side to the secondary side of the steam generator.

[0010] The method for calculating the leakage rate from the primary side to the secondary side of the steam generator of the present invention is simple and reliable. According to the boron concentration data in the steam generator blowdown system, the steam generator water supply system and the main steam system, and in combination with the boron concentration data in the water contained in the primary side of the steam generator and the boron concentration data in the water contained in the secondary side of the steam generator, the leakage rate from the primary side to the secondary side of the steam generator is accurately calculated. The calculation method can be widely used in the leakage rate detection from the primary side to the secondary side of the steam generator of nuclear power projects, and has broad application prospects.

[0011] The leakage rate in the method for calculating the leakage rate from the primary side to the secondary side of the steam generator described in the present invention refers to the ratio of the boron concentration leaked from the primary side to the secondary side of the steam generator to the boron concentration of the primary circuit per unit time, and the unit is m 3 / h, the leakage rate is a relative value, taking the volume into consideration.

[0012] Preferably, the calculation method specifically comprises the following steps:

[0013] (1) After the unit has been running at a steady state for more than 12 hours, the primary circuit charging and makeup water, downstream flow, stabilizer exhaust and primary circuit sampling flow are isolated, and then the primary circuit is sampled and tested to obtain the boron concentration, which is recorded as B 一次侧 ;

[0014] (2) At time t1, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system, and the boron concentrations are measured and recorded as B 排污t1 , B 给水t1 , B 主蒸汽t1 ;

[0015] (3) Based on the steam generator liquid level data, calculate the water loading V on the secondary side of the steam generator at time t1 SGt1 ;

[0016] (4) At an interval of ΔT, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system at time t2, and the boron concentrations of the samples are measured and recorded as B 排污t2 , B 给水t2 , B 主蒸汽t2 ;

[0017] (5) According to the steam generator liquid level, calculate the water charge V on the secondary side of the steam generator at time t2. SGt2 ;

[0018] (6) Obtain the total volume V of the steam generator sewage system and steam generator water supply system from t1 to t2 排污t1-2 、V 给水t1-2 Finally, combined with the change in the water volume of the steam generator, the total volume V of the main steam is calculated. 主蒸汽t1-2 ;

[0019] (7) The leakage rate is calculated based on the ratio of the change in boron concentration on the secondary side of the steam generator to the boron concentration in the primary circuit, and the leakage rate is calculated as follows:

[0020]

[0021] The calculation method of the present invention quickly converts the total volume of the main steam system by the change of the water charge of the steam generator and the total volume of the steam generator sewage system and the steam generator water supply system, thereby solving the problem that the main steam flow rate is low and cannot be read by the instrument during the hot test, and can accurately obtain the leakage rate from the primary side to the secondary side of the steam generator, thereby ensuring that the radioactive substances in the first circuit will not diffuse to the second circuit through the steam generator heat transfer tube.

[0022] Preferably, the evaluation criteria for the steady-state operation of the unit in step (1) is: the fluctuation range of the stabilizer liquid level is -0.5% to 0.5%, for example, it can be -0.5%, -0.3%, -0.1%, 0.1%, 0.2%, 0.4% or 0.5%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] The temperature fluctuation range of a circuit is -0.5% to 0.5%, for example, it can be -0.5%, -0.3%, -0.1%, 0.1%, 0.2%, 0.4% or 0.5%, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0024] Preferably, the boron concentration in step (1) is tested using an inductively coupled plasma mass spectrometer.

[0025] Preferably, the ΔT in step (4) is 0.5 to 2 h, for example, 0.5 h, 0.6 h, 0.8 h, 1 h, 1.3 h, 1.5 h or 2 h, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the total volume V of the steam generator blowdown system in step (6) is 排污t1-2 The flow data is obtained by acquiring it through the flow detection device and multiplying it with the time data.

[0027] Preferably, the total volume V in the steam generator feed water system in step (6) is 给水t1-2 The flow data is obtained by acquiring it through the flow detection device and multiplying it with the time data.

[0028] Preferably, the total volume V of the main steam in step (6) is 主蒸汽t1-2 The calculation formula is:

[0029] V 主蒸汽t1-2 =((V SGt2 -V SGt1 )+V 给水t1-2 -V 排污t1-2 .

[0030] Preferably, the total volume V of the main steam in step (6) is 主蒸汽t1-2The volume of steam converted to water.

[0031] As a preferred technical solution of the present invention, the calculation method specifically includes the following steps:

[0032] (1) The fluctuation range of the pressurizer liquid level is -0.5% to 0.5%, and the fluctuation range of the primary circuit temperature is -0.5% to 0.5%. The unit is in steady state operation for more than 12 hours. After isolating the primary circuit upstream water filling, downstream flow, pressurizer exhaust and primary circuit sampling flow, the primary circuit is sampled and the boron concentration is obtained by testing, which is recorded as B 一次侧 ; The boron concentration is tested using an inductively coupled plasma mass spectrometer;

[0033] (2) At time t1, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system, and the boron concentrations are measured and recorded as B 排污t1 , B 给水t1 , B 主蒸汽t1 ;

[0034] (3) Based on the steam generator liquid level data, calculate the water loading V on the secondary side of the steam generator at time t1 SGt1 ;

[0035] (4) At an interval of ΔT, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system at time t2, and the boron concentrations of the samples are measured and recorded as B 排污t2 , B 给水t2 , B 主蒸汽t2 ; The ΔT is 0.5 to 2 hours;

[0036] (5) According to the steam generator liquid level, calculate the water charge V on the secondary side of the steam generator at time t2. SGt2 ;

[0037] (6) After the flow data is obtained by the flow detection device, it is multiplied by the time data to obtain the total volume V of the steam generator sewage system from t1 to t2 排污t1-2 After obtaining the flow data through the flow detection device, multiply it by the time data to obtain V in the steam generator feedwater system from t1 to t2. 给水t1-2 Finally, combined with the change in the water volume of the steam generator, the total volume V of the main steam is calculated. 主蒸汽t1-2 ;

[0038] (7) The leakage rate is calculated based on the ratio of the change in boron concentration on the secondary side of the steam generator to the boron concentration in the primary circuit, and the leakage rate is calculated as follows:

[0039]

[0040] Compared with the prior art, the present invention has at least the following beneficial effects:

[0041] The method for calculating the leakage rate from the primary side to the secondary side of a steam generator provided by the present invention has a simple principle, can accurately calculate the leakage rate from the primary side to the secondary side of the steam generator, verify that it meets the design requirements, and ensure that the radioactive material in the primary circuit will not diffuse to the secondary circuit through the steam generator heat transfer tube. The method is suitable for the leakage rate calculation of the steam generator of a nuclear power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a flow chart of a method for calculating the leakage rate from the primary side to the secondary side of a steam generator provided by the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0044] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0045] As a specific embodiment of the present invention, a method for calculating the leakage rate from the primary side to the secondary side of a steam generator is provided, and a flow chart thereof is shown as follows: Figure 1 shown.

[0046] In this specific implementation, according to the requirements of the nuclear power plant for the boron concentration in the primary circuit, the boron concentration is maintained within the range of 500-600 ppm.

[0047] The calculation method specifically comprises the following steps:

[0048] (1) The fluctuation range of the pressurizer liquid level is -0.5% to 0.5%, and the fluctuation range of the primary circuit temperature is -0.5% to 0.5%. The unit is in steady state operation for more than 12 hours. After isolating the primary circuit upstream water filling, downstream flow, pressurizer exhaust and primary circuit sampling flow, the primary circuit is sampled and the boron concentration is obtained by testing, which is recorded as B 一次侧 , specifically 563ppm; the boron concentration is tested using an inductively coupled plasma mass spectrometer;

[0049] (2) At time t1, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system, and the boron concentrations are measured and recorded as B 排污t1 , specifically 0.2ppb, B 给水t1 , specifically 0.2ppb, B 主蒸汽t1 , specifically 0.2ppb;

[0050] (3) Based on the steam generator liquid level data, calculate the water loading V on the secondary side of the steam generator at time t1 SGt1 , specifically 200.2m 3 ;

[0051] (4) At an interval of ΔT, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system at time t2, and the boron concentrations of the samples are measured and recorded as B 排污t2 , specifically 0.2ppb, B 给水t2 , specifically 0.2ppb, B 主蒸汽t2 , specifically 0.2ppb; the ΔT is 1h;

[0052] (5) According to the steam generator liquid level, calculate the water charge V on the secondary side of the steam generator at time t2. SGt2 , specifically 200.2m 3 ;

[0053] (6) After the flow data is obtained by the flow detection device, it is multiplied by the time data to obtain the total volume V of the steam generator sewage system from t1 to t2 排污t1-2 , specifically 12.62m 3 After obtaining the flow data through the flow detection device, multiply it by the time data to obtain V in the steam generator feedwater system from t1 to t2. 给水t1-2 , specifically 22.20m 3 Finally, combined with the change in the water volume of the steam generator, the total volume V of the main steam is calculated. 主蒸汽t1-2 , specifically 9.58m 3 ;

[0054] (7) The leakage rate is calculated based on the ratio of the change in boron concentration on the secondary side of the steam generator to the boron concentration in the primary circuit, and the leakage rate is calculated as follows:

[0055]

[0056] The leakage rate is 0.

[0057] It can be seen from the results that in this specific implementation, no leakage occurs from the primary side to the secondary side of the steam generator, and the nuclear power unit can operate safely and stably.

[0058] In summary, the method for calculating the leakage rate from the primary side to the secondary side of the steam generator provided by the present invention is simple in principle, and can accurately calculate the leakage rate from the primary side to the secondary side of the steam generator, verify that it meets the design requirements, and ensure that the radioactive substances in the first circuit will not diffuse to the second circuit through the steam generator heat transfer tube.

[0059] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for calculating the leakage rate from the primary side to the secondary side of a steam generator, characterized in that: The calculation method includes: using the boron concentration data in the water contained in the primary side of the steam generator, the boron concentration data in the water contained in the secondary side of the steam generator, and the boron concentration data in the steam generator sewage system, the steam generator water supply system and the main steam system, to calculate the leakage rate from the primary side of the steam generator to the secondary side.

2. The leakage rate calculation method according to claim 1, characterized in that: The calculation method specifically comprises the following steps: (1) After the unit has been running at a steady state for more than 12 hours, the primary circuit charging and makeup water, downstream flow, stabilizer exhaust and primary circuit sampling flow are isolated, and then the primary circuit is sampled and tested to obtain the boron concentration, which is recorded as B 一次侧 ; (2) At time t1, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system, and the boron concentrations are measured and recorded as B 排污t1 , B 给水t1 , B 主蒸汽t1 ; (3) Based on the steam generator liquid level data, calculate the water loading V on the secondary side of the steam generator at time t1 SGt1 ; (4) At an interval of ΔT, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system at time t2, and the boron concentrations of the samples are measured and recorded as B 排污t2 , B 给水t2 , B 主蒸汽t2 ; (5) According to the steam generator liquid level, calculate the water charge V on the secondary side of the steam generator at time t2. SGt2 ; (6) Obtain the total volume V of the steam generator sewage system and steam generator water supply system from t1 to t2 排污t1-2 、V 给水t1-2 Finally, combined with the change in the water volume of the steam generator, the total volume V of the main steam is calculated. 主蒸汽t1-2 ; (7) The leakage rate is calculated based on the ratio of the change in boron concentration on the secondary side of the steam generator to the boron concentration in the primary circuit, and the leakage rate is calculated as follows:

3. The leakage rate calculation method according to claim 1 or 2, characterized in that: The evaluation criteria for the steady-state operation of the unit in step (1) are: the fluctuation range of the pressurizer liquid level is -0.5% to 0.5%, and the fluctuation range of the primary circuit temperature is -0.5% to 0.5%.

4. The leakage rate calculation method according to any one of claims 1 to 3, characterized in that: The boron concentration in step (1) is tested using an inductively coupled plasma mass spectrometer.

5. The leakage rate calculation method according to any one of claims 1 to 4, characterized in that: The ΔT in step (4) is 0.5 to 2 hours.

6. The leakage rate calculation method according to any one of claims 1 to 5, characterized in that: The total volume V of the steam generator blowdown system in step (6) 排污t1-2 The flow data is obtained by acquiring it through the flow detection device and multiplying it with the time data.

7. The leakage rate calculation method according to any one of claims 1 to 6, characterized in that: The total volume V in the steam generator feedwater system in step (6) 给水t1-2 The flow data is obtained by acquiring it through the flow detection device and multiplying it with the time data.

8. The leakage rate calculation method according to any one of claims 1 to 7, characterized in that: The total volume V of the main steam in step (6) 主蒸汽t1-2 The calculation formula is: V 主蒸汽t1-2 =(V SGt2 -V SGt1 )+V 给水t1-2 -V 排污t1-2 。 9. The leakage rate calculation method according to any one of claims 1 to 8, characterized in that: The total volume V of the main steam in step (6) 主蒸汽t1-2 The volume of steam converted to water.

10. The leakage rate calculation method according to any one of claims 1 to 9, characterized in that: The calculation method specifically comprises the following steps: (1) The fluctuation range of the pressurizer liquid level is -0.5% to 0.5%, and the fluctuation range of the primary circuit temperature is -0.5% to 0.5%. The unit is in steady state operation for more than 12 hours. After isolating the primary circuit upstream water filling, downstream flow, pressurizer exhaust and primary circuit sampling flow, the primary circuit is sampled and the boron concentration is obtained by testing, which is recorded as B 一次侧 ; The boron concentration is tested using an inductively coupled plasma mass spectrometer; (2) At time t1, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system, and the boron concentrations are measured and recorded as B 排污t1 , B 给水t1 , B 主蒸汽t1 ; (3) Based on the steam generator liquid level data, calculate the water loading V on the secondary side of the steam generator at time t1 SGt1 ; (4) At an interval of ΔT, samples are taken from the steam generator blowdown system, steam generator feedwater system, and main steam system at time t2, and the boron concentrations of the samples are measured and recorded as B 排污t2 , B 给水t2 , B 主蒸汽t2 ; The ΔT is 0.5 to 2 hours; (5) According to the steam generator liquid level, calculate the water charge V on the secondary side of the steam generator at time t2. SGt2 ; (6) After the flow data is obtained by the flow detection device, it is multiplied by the time data to obtain the total volume V of the steam generator sewage system from t1 to t2 排污t1-2 After obtaining the flow data through the flow detection device, multiply it by the time data to obtain V in the steam generator feedwater system from t1 to t2. 给水t1-2 Finally, combined with the change in the water volume of the steam generator, the total volume V of the main steam is calculated. 主蒸汽t1-2 ; (7) The leakage rate is calculated based on the ratio of the change in boron concentration on the secondary side of the steam generator to the boron concentration in the primary circuit, and the leakage rate is calculated as follows:

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