A method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant

Abstract

This invention relates to the field of nuclear power plant reactor coolant loading evaluation technology, specifically disclosing a method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant, comprising the following steps: Step 1: Define the standard working environment for calculating the primary loop leakage rate during power operation; Step 2: Calculate the primary loop leakage rate (control tank component) based on the change in the control tank level; Step 3: Calculate the primary loop leakage rate (pressurizer component) based on the change in the total mass of the pressurizer; Step 4: Calculate the primary loop leakage rate (average temperature component) based on the change in the primary loop average temperature; Step 5: Calculate the primary loop leakage rate (makeup water component) based on the boronization / dilution amount; Step 6: Calculate the primary loop leakage rate (waste water component) based on the change in the boron recovery system level; Step 7: Summarize the values ​​of each component of the primary loop leakage rate to obtain the primary loop leakage rate. This invention considers the influence of pressure on the pressurizer water loading in steam-water coexisting systems and fully analyzes the evaporation and condensation of steam in the pressurizer, resulting in more accurate calculation results.

Description

Technical Field

[0001] This invention belongs to the technical field of nuclear power plant reactor coolant loading evaluation, specifically relating to a method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant. Background Technology

[0002] According to the nuclear power plant license document, "Requirements for Periodic Testing and Supervision of Safety-Related Systems and Equipment," nuclear power plants must perform daily leakage rate tests to calculate the reactor coolant leakage rate. Currently, nuclear power plants calculate the reactor leakage rate by comparing the volume changes of relevant containers in the primary loop over a period of time (more than 2 hours) and adjusting for changes in the primary loop average temperature. This calculation method has the following shortcomings:

[0003] 1. Pressure fluctuations of the voltage regulator were not considered.

[0004] When pressure changes, the saturated water and saturated steam in the pressurizer undergo density changes and physical changes such as evaporation / condensation. This affects the calculation of the water load in the primary loop, and this deviation should not be reflected in the change in leakage rate. The results of evaporation and condensation can be reflected in the density change of the pressurizer, but density changes are not directly detectable. Therefore, the impact of pressure changes on the water load in the pressurizer must be considered.

[0005] 2. The inconsistent temperature and pressure at different parts of the primary circuit were not considered.

[0006] The physical parameters of the coolant (water) are different at different locations in the primary circuit, and the leakage rates obtained from different parts cannot be directly added or subtracted. The original calculation method did not take this issue into account, hence the significant deviation.

[0007] 3. The accuracy of the calculation results is low.

[0008] Currently, the parameters used to calculate leakage rates all rely on single instruments, and these instruments have a certain degree of error (theoretically up to 4% of the instrument's range). Therefore, the calculated leakage rate results may deviate significantly due to the normal error of the instrument. Taking the primary loop average temperature gauge RCP619KM as an example, a deviation of 0.1℃ over a 2-hour time interval would result in a flow rate deviation of 35.45 L / h. The normal primary loop leakage rate of a pressurized water reactor is between 20-30 L / h, meaning this deviation is on the order of magnitude of the normal leakage rate.

[0009] 4. The calculation methods are complex and diverse.

[0010] Existing calculation methods require two different formulas depending on the working conditions:

[0011] (1) If no boronizing dilution is performed during the 2-hour test period, the formula for calculating the leakage rate is:

[0012]

[0013] in:

[0014] Fp is the primary loop leakage rate, in L / h;

[0015] N1 is the value of the liquid level RCV011MN in the control tank when the leakage rate is first calculated, in cm;

[0016] N2 is the value of the liquid level RCV011MN in the control tank when the leakage rate calculation is completed, in cm;

[0017] N3 is the value of the regulator liquid level RCP007MN when the leakage rate is first calculated, in meters;

[0018] N4 is the value of the regulator liquid level RCP007MN when the leakage rate calculation ends, in meters;

[0019] T1 is the value of the average primary loop temperature RCP619KM at the start of leakage rate calculation, in °C;

[0020] T2 is the value of the average temperature of the primary loop at 619 KM when the leakage rate calculation is completed, in °C.

[0021] Δt represents the time for calculating the leakage, in hours (h).

[0022] (2) If boronizing / dilution is performed during the 2-hour test period, the formula for calculating the leakage rate is:

[0023]

[0024] in:

[0025] V_boration / dilution is the total volume of co-boration / dilution entering the primary circuit during the test, in L;

[0026] N5 is the value of the TEP head tank level TEP001MN when the leakage rate is first calculated, in meters;

[0027] N6 represents the TEP head tank level TEP001MN at the end of the leakage rate calculation, in meters.

[0028] In summary, there is an urgent need to propose a more comprehensive and accurate method for calculating the reactor coolant leakage rate of pressurized water reactor nuclear power plants in order to solve the above problems. Summary of the Invention

[0029] The purpose of this invention is to provide a method for calculating the reactor coolant leakage rate in pressurized water reactor nuclear power plants, so as to effectively improve the accuracy and comprehensiveness of the calculation of reactor coolant leakage rate.

[0030] The technical solution of the present invention is as follows:

[0031] A method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant, taking into account the leakage rate of the entire primary loop, including the control box, pressurizer, primary loop water body, boron recovery system headbox that receives primary loop wastewater, and boron and water supply system that replenishes water to the primary loop.

[0032] Includes the following steps:

[0033] Step 1: Define the standard operating environment for calculating the leakage rate of the primary loop during power operation;

[0034] Step 2: Calculate the primary loop leakage rate (capacity control box component) based on the liquid level change in the control box;

[0035] Step 3: Calculate the primary loop leakage rate of the voltage regulator based on the change in the total mass of the voltage regulator;

[0036] Step 4: Calculate the average temperature component of the primary loop leakage rate based on the change in the primary loop average temperature;

[0037] Step 5: Calculate the primary loop leakage rate water replenishment item based on the borylation / dilution amount;

[0038] Step 6: Calculate the primary loop leakage rate and wastewater percentage based on the boron recovery system level changes;

[0039] Step 7: Summarize the values ​​of each component of the primary loop leakage rate to obtain the primary loop leakage rate.

[0040] In step 1, the working environment of the container control box is taken as the standard working environment, and the density of water is ρ.

[0041] In step 2, considering the impact of changes in the liquid level in the control tank on the primary loop leakage rate, the leakage rate of the control tank component is:

[0042] Unit: L / h;

[0043] S1 is the cross-sectional area of ​​the control box, in m². 2 ;

[0044] N11 and N12 are the values ​​of the two level gauges in the control box when the leakage rate is first calculated, in cm;

[0045] N21 and N22 are the values ​​of the two level gauges in the control box when the leakage rate calculation is completed, in cm;

[0046] △t represents the time interval before and after calculating the leakage rate, in hours.

[0047] In step 3, considering that not only the liquid level affects the water level in the pressure regulator, but also pressure changes leading to steam evaporation or condensation, and changes in the density of steam or saturated water, the water level before the test is:

[0048]

[0049] N31, N32, and N33 are the values ​​of the three level gauges of the pressure regulator when the leakage rate is first calculated, in meters (m).

[0050] S2 is the cross-sectional area of ​​the voltage regulator, in meters (m²). 2 ;

[0051] L 下限 This is the lower limit of the range of the level gauge for the pressure regulator, in meters (m).

[0052] L 上限 The upper limit of the level gauge range for the pressure regulator, in meters (m).

[0053] Interpolation revealed that the density of saturated water at 15.5 MPa·a is 594.0416 kg / m³. 3 The density of saturated steam is 101.9430 kg / m³. 3 The density of saturated water changes with pressure at a rate of -18.3495 kg / (m³). 3 The saturated steam density changes with pressure at a rate of 10.7545 kg / (m³). 3 (·MPa);

[0054] ρ'1 is the density of saturated water in the voltage regulator calculated before the test, in kg / m³. 3 ,

[0055]

[0056] ρ″1 is the density of saturated steam in the pressure regulator calculated before the test, in kg / m³. 3 ,

[0057]

[0058] P11, P12, P13, P14, and P15 are the values ​​of the five pressure gauges on the voltage regulator before the test, in MPa.g.

[0059] The water volume after the test was:

[0060]

[0061] N41, N42, and N43 are the values ​​of the three level gauges of the pressure regulator when the leakage rate calculation is completed, in meters (m).

[0062] ρ'2 is the density of saturated water in the voltage regulator calculated after the experiment, in kg / m³. 3 ,

[0063]

[0064] ρ″2 is the density of saturated steam in the pressure regulator calculated after the experiment, in kg / m³. 3 ,

[0065]

[0066] P21, P22, P23, P24, and P25 are the values ​​of the five pressure gauges on the voltage regulator after the test, in MPa.g.

[0067] 15.4 is the actual measured value of the unit gauge pressure when calculating the density of saturated water or saturated steam in the pressurizer, used as a pressure correction value, in MPa.g;

[0068] The mass difference Δm before and after the test is:

[0069]

[0070] The leakage rate of the voltage regulator component is:

[0071] Unit: L / h;

[0072] △t represents the time interval before and after calculating the leakage rate, in hours (h).

[0073] ρ is the density of water under standard working conditions, in kg / m³. 3 .

[0074] In step 4, the result of the average temperature sub-item calculation is taken as a negative value;

[0075] Calculate the total primary circuit volume V excluding the voltage regulator: V = Total primary circuit volume - Total voltage regulator volume, unit m. 3 ;

[0076] During the operation of the M310 unit at full power, the average temperature of the primary circuit ranged from 291.4℃ to 310℃. The density of water at different temperatures was as follows:

[0077] ρ 一回路 =740.0172-(T) 一回路 -285.79)×2.0492,

[0078] In the formula ρ 一回路 It is the density of the coolant in the primary circuit, T 一回路 It is the average temperature of the primary coolant;

[0079] When the temperature changes, the change in the total volume of the primary loop is:

[0080]

[0081] In the above formula:

[0082] V represents the total volume of the primary circuit excluding the voltage regulator, in units of 178m³. 3 ;

[0083] ρ is the density of water under standard working conditions, expressed in kg / m³. 3 ;

[0084] ρ 一回路1 The density of the primary coolant before the test is expressed in kg / m³. 3 ;

[0085] ρ 一回路2 The density of the primary coolant after the test is expressed in kg / m³. 3 ;

[0086] T 一回路1 The average temperature of the primary coolant before the test, in °C;

[0087] T 一回路2 The average temperature of the primary coolant after the test, in °C;

[0088] Since the primary loop has three identical loops, and each loop has its own average temperature gauge, the average temperature of the primary loop is the average of the average temperatures of the three loops, that is:

[0089]

[0090] T11, T12, and T13 are the values ​​of the three average temperature gauges in the primary loop at the beginning of the leakage rate calculation, in °C.

[0091] T21, T22, and T23 are the values ​​of the three average temperature gauges in the primary loop at the end of the leakage rate calculation, in °C.

[0092] The leakage rate for the average temperature component is:

[0093] Unit: L / h;

[0094] △t represents the time interval before and after calculating the leakage rate, in hours.

[0095] In step 5, if borylation / dilution is performed on the primary loop during the calculation of the primary loop leakage rate, it is actually a water replenishment operation on the primary loop, and the amount of borylation / dilution can be read directly.

[0096] The leakage rate of the water replenishment item is:

[0097] Unit: L / h;

[0098] Where V 硼化 / 稀释 Boration / dilution amount, in liters (L);

[0099] △t represents the time interval before and after calculating the leakage rate, in hours.

[0100] In step 6, the boron recovery system is responsible for collecting the leaked coolant from the primary loop. The collected coolant is concentrated in the wastewater head tank; therefore, the leakage rate of the wastewater is:

[0101] Unit: L / h;

[0102] S3 is the cross-sectional area of ​​the wastewater head tank, in meters (m²). 2 ;

[0103] N5 represents the liquid level in the head tank of the boron recovery system before the test, in meters (m).

[0104] N6 is the liquid level in the head tank of the boron recovery system after the test, in meters (m).

[0105] △t represents the time interval before and after calculating the leakage rate, in hours.

[0106] In step 7, the leakage rate items calculated in steps 2 to 6 are added together to obtain the primary loop leakage rate F. p .

[0107] In step 7, the primary loop leakage rate F p for:

[0108] Unit: L / h;

[0109] In the formula,

[0110] N11 and N12 are the values ​​of the two level gauges in the control box when the leakage rate is first calculated, in cm;

[0111] N21 and N22 are the values ​​of the two level gauges in the control box when the leakage rate calculation is completed, in cm;

[0112] △t represents the time before and after calculating the leakage rate, in hours.

[0113] ρ is the density of water under standard working conditions, in kg / m³. 3 ;

[0114]

[0115] N31, N32, and N33 are the values ​​of the three level gauges of the pressure regulator when the leakage rate is first calculated, in meters (m).

[0116] N41, N42, and N43 are the values ​​of the three level gauges of the pressure regulator when the leakage rate calculation is completed, in meters (m).

[0117]

[0118]

[0119] P11, P12, P13, P14, and P15 are the values ​​of the pressure gauges of the five voltage regulators before the test, in MPa.g.

[0120]

[0121]

[0122] P21, P22, P23, P24, and P25 are the values ​​of the pressure gauges of the five voltage regulators after the test, in MPa.g.

[0123] T11, T12, and T13 are the values ​​of the three average temperature gauges in the primary loop at the beginning of the leakage rate calculation, in °C.

[0124] T21, T22, and T23 are the values ​​of the three average temperature gauges in the primary loop at the end of the leakage rate calculation, in °C.

[0125] V 硼化 / 稀释 Boration / dilution amount, in liters (L);

[0126] N5 represents the liquid level in the head tank of the boron recovery system before the test, in meters (m).

[0127] N6 is the liquid level in the head tank of the boron recovery system after the test, in meters (m).

[0128] S1 is the cross-sectional area of ​​the control box, in m². 2 ;

[0129] S2 is the cross-sectional area of ​​the voltage regulator, in meters (m²). 2 ;

[0130] S3 is the cross-sectional area of ​​the wastewater head tank, in meters (m²). 2 .

[0131] The significant advantages of this invention are:

[0132] (1) This invention is not limited by the calculation of the primary coolant leakage rate in the prior art. It creatively considers the influence of pressure on the water volume of the pressure regulator in the case of steam and water coexistence, and fully analyzes the evaporation and condensation of steam in the pressure regulator, so the calculation results are more accurate.

[0133] (2) The present invention takes into account the different temperatures and pressures, and different coolant densities of various parts involved in the primary circuit, and normalizes the leakage rate calculation formula to simplify the calculation method.

[0134] (3) The present invention utilizes multiple similar instruments in coordination, which to some extent eliminates the influence of the deviation of a single instrument, and the calculation results are more stable.

[0135] (4) The method of the present invention can effectively reduce the probability and magnitude of unreasonable extreme leakage rate values, and the range of the statistical calculation results is smaller.

[0136] (5) The method of the present invention no longer distinguishes whether boronizing / dilution (water replenishment) is performed during the test, and the leakage rate calculation idea is clearer.

[0137] (6) The formulas involved in the method of the present invention can be prepared by software and used. Only the known values ​​need to be input, and the corresponding conversion results can be obtained immediately, which improves the calculation efficiency, reduces the risk of errors, and facilitates promotion. Detailed Implementation

[0138] The present invention will be further described in detail below with reference to specific embodiments.

[0139] A method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant considers the leakage rate of the entire primary loop, including the containment control box, pressurizer, primary loop water body, the boron recovery system (TEP) headbox that receives primary loop wastewater, and the boron and water makeup system (REA) that supplies makeup water to the primary loop. The calculation method includes the following steps:

[0140] Step 1: Define the standard operating environment for calculating the leakage rate of the primary loop during power operation.

[0141] Since the volume change in the primary loop is ultimately reflected within the control box, the operating environment of the control box is taken as the standard operating environment. The temperature of the control box is 30℃, the pressure is 0.13MPa.g, the gas phase is hydrogen, and the density of water at this time is ρ=995.676kg / m³. 3 ;

[0142] Step 2: Calculate the primary loop leakage rate (control tank sub-item) based on the liquid level change in the control tank.

[0143] Considering the impact of changes in the liquid level in the control tank on the primary loop leakage rate, the leakage rate of the control tank component is:

[0144] Unit: L / h;

[0145] S1 is the cross-sectional area of ​​the control box, in m². 2 ;

[0146] The coefficient 10 is a multiplier generated by unit conversion;

[0147] N11 and N12 are the values ​​of the two level gauges in the control box when the leakage rate is first calculated, in cm;

[0148] N21 and N22 are the values ​​of the two level gauges in the control box when the leakage rate calculation is completed, in cm;

[0149] △t represents the time interval before and after calculating the leakage rate, in hours (h).

[0150] Step 3: Calculate the primary loop leakage rate (voltage regulator component) based on the change in the total mass of the voltage regulator.

[0151] There is only one voltage regulator in the primary circuit. The voltage regulator is different from the control box. Under normal conditions, the voltage regulator contains both vapor and liquid phases, and the normal pressure is 15.5 MPa.

[0152] Not only does the liquid level affect the water capacity of the pressurizer, but pressure changes leading to steam evaporation / condensation, and changes in the density of steam and saturated water also affect the water capacity. Therefore, calculating the total mass change of the pressurizer requires calculating the total mass before and after the test; refer to the parameter comparison table for saturated water and steam:

[0153]

[0154] Interpolation revealed that the density of saturated water at 15.5 MPa·a is 594.0416 kg / m³. 3 The density of saturated steam is 101.9430 kg / m³. 3 The density of saturated water changes with pressure at a rate of -18.3495 kg / (m³). 3 The saturated steam density changes with pressure at a rate of 10.7545 kg / (m³). 3 (·MPa);

[0155] Therefore, at a pressure of approximately 15.5 MPa, the density of saturated water can be approximated as:

[0156] ρ′ P =ρ′ 15.5 -18.3495×(P-15.5)=594.0416-18.3495×(P-15.5),

[0157] The pressure of saturated steam can be approximated as:

[0158] ρ″ P =ρ″ 15.5 +10.7545×(P-15.5)=101.9430+10.7545×(P-15.5),

[0159] The voltage regulator is a cylinder with three level gauges and five pressure gauges.

[0160] The lower limit of the range of the voltage regulator level gauge is L. 下限 Therefore, the water volume of the voltage regulator is:

[0161]

[0162] The upper limit of the range of the level gauge for the pressure regulator is L. 上限 Therefore, the total volume of the gas phase of the voltage regulator is:

[0163]

[0164] Therefore, the water volume before the experiment was:

[0165]

[0166] N31, N32, and N33 are the values ​​of the three level gauges of the pressure regulator when the leakage rate is first calculated, in meters (m).

[0167] S2 is the cross-sectional area of ​​the voltage regulator, in meters (m²). 2 ;

[0168] L 下限 This is the lower limit of the range of the level gauge for the pressure regulator, in meters (m).

[0169] L 上限 The upper limit of the level gauge range for the pressure regulator, in meters (m).

[0170] ρ'1 is the density of saturated water in the voltage regulator calculated before the test, in kg / m³. 3 ;

[0171]

[0172] ρ″1 is the density of saturated steam in the pressure regulator calculated before the test, in kg / m³. 3 ;

[0173]

[0174] P11, P12, P13, P14, and P15 are the values ​​of the five pressure gauges on the voltage regulator before the test, in MPa.g.

[0175] The water volume after the test was:

[0176]

[0177] N41, N42, and N43 are the values ​​of the three level gauges of the pressure regulator when the leakage rate calculation is completed, in meters (m).

[0178] ρ'2 is the density of saturated water in the voltage regulator calculated after the experiment, in kg / m³. 3 ;

[0179]

[0180] ρ″2 is the density of saturated steam in the pressure regulator calculated after the experiment, in kg / m³. 3 ;

[0181]

[0182] P21, P22, P23, P24, and P25 are the values ​​of the five pressure gauges on the voltage regulator after the test, in MPa.g.

[0183] Since the measured pressures in the unit are all gauge pressures, the pressure correction value of 15.5 MPa.a when calculating the density of saturated water or saturated steam in the pressurizer is changed to 15.4 MPa.g; where 15.5 MPa is the absolute pressure during reactor operation and 15.4 MPa is the gauge pressure.

[0184] The mass difference Δm before and after the test is:

[0185]

[0186] The leakage rate of the voltage regulator component is: Unit: L / h;

[0187] It is important to note that ρ here refers to the water density under the reference temperature and pressure of the control tank, i.e., the density of water under standard operating conditions ρ = 995.676 kg / m³. 3 1000 is for standardizing m 3 The conversion factor to L;

[0188] Step 4: Calculate the primary loop leakage rate (average temperature component) based on the primary loop average temperature change.

[0189] The coolant in the primary loop is unsaturated water. Changes in the average temperature will cause the coolant to expand and contract. This volume change will affect the calculated leakage rate, but it is not the actual leakage of the primary loop. Therefore, this part must be excluded when calculating the leakage rate, i.e., the result of this sub-item calculation is negative. It is worth mentioning that although the primary loop is connected to the voltage regulator, the temperature of the working fluid in the voltage regulator does not change with the average temperature of the primary loop. It is always at the saturation temperature. Therefore, the total volume of the primary loop excluding the voltage regulator can only be calculated.

[0190] The total volume of one circuit, including the voltage regulator, is 199m³. 3 The total volume of the voltage regulator is 21m³. 3 Therefore, the calculated total volume of the primary circuit excluding the voltage regulator is V = 199 - 21 = 178 m³. 3 ;

[0191] During full-capacity operation of the M310 unit, the average temperature of the primary circuit ranges from 291.4℃ to 310℃. The water parameters under these conditions are shown in the table below:

[0192] Temperature / °C 285.79 294.97 303.31 310.96 <![CDATA[Specific volume / (m 3 / kg)]]> 0.001351 0.001384 0.001418 0.001453 <![CDATA[Density / (kg / m 3 )]]> 740.0172 722.4129 705.2883 688.4397

[0193] The density of water at different temperatures can be obtained from the differences in the table above:

[0194] ρ 一回路 =740.0172-(T) 一回路 -285.79)×2.0492

[0195] In the formula ρ 一回路 It is the density of the coolant in the primary circuit, T 一回路 It is the average temperature of the primary coolant; K = 2.0492 is the temperature-density ratio coefficient of water, calculated by substituting the parameters in the table above.

[0196] When the temperature changes, the change in the total volume of the primary loop is:

[0197]

[0198] In the above formula:

[0199] V is the total volume of the primary circuit excluding the voltage regulator, in meters. 3 ;

[0200] ρ is the density of water under standard working conditions, expressed in kg / m³. 3 ;

[0201] ρ 一回路1 The density of the primary coolant before the test is expressed in kg / m³. 3 ;

[0202] ρ 一回路2 The density of the primary coolant after the test is expressed in kg / m³. 3 ;

[0203] T 一回路1 The average temperature of the primary coolant before the test, in °C;

[0204] T 一回路2 The average temperature of the primary coolant after the test, in °C;

[0205] Since the primary loop has three identical loops, and each loop has its own average temperature gauge, the average temperature of the primary loop is the average of the average temperatures of the three loops, that is:

[0206]

[0207] T11, T12, and T13 are the values ​​of the three average temperature gauges in the primary loop at the beginning of the leakage rate calculation, in °C.

[0208] T21, T22, and T23 are the values ​​of the three average temperature gauges in the primary loop at the end of the leakage rate calculation, in °C.

[0209] The leakage rate for the average temperature component is:

[0210] Unit: L / h;

[0211] In the formula, 1000 represents m 3 Convert to L-fold ratio;

[0212] Step 5: Calculate the primary loop leakage rate (water replenishment item) based on the borylation / dilution amount.

[0213] During the calculation of the primary loop leakage rate, if borying / dilution operations are performed on the primary loop, this is actually makeup water for the primary loop. The amount of borying / dilution can be directly read in liters (L). Therefore, the leakage rate for the makeup water item is:

[0214] Unit: L / h;

[0215] Where V 硼化 / 稀释 Boration / dilution amount, in liters (L);

[0216] Step 6: Calculate the primary loop leakage rate (wastewater component) based on the boron recovery system (TEP) level changes.

[0217] The boron recovery system is responsible for collecting leaked coolant from the primary loop. The collected coolant is concentrated in the wastewater head tank. Since the cross-sectional area of ​​the wastewater head tank is S3, the leakage rate of the wastewater is as follows:

[0218] Unit: L / h;

[0219] N5 represents the liquid level in the head tank of the boron recovery system before the test, in meters (m).

[0220] N6 is the liquid level in the head tank of the boron recovery system after the test, in meters (m).

[0221] In the formula, m 3 The value was converted to L and then a multiplier was calculated.

[0222] Step 7: Summarize the individual values ​​of the primary loop leakage rate.

[0223] The leakage rate items calculated in steps 2 to 6 are added together to obtain the primary loop leakage rate; the average temperature item should be subtracted from the leakage rate, so it is taken as a negative value.

[0224] Primary loop leakage rate F pfor:

[0225] Unit: L / h.

[0226] Example

[0227] A method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant includes the following steps:

[0228] Step 1: Define the standard operating environment for calculating the leakage rate of the primary loop during power operation.

[0229] Since the volume change in the primary loop is ultimately reflected within the control box, the operating environment of the control box is taken as the standard operating environment. The temperature of the control box is 30℃, the pressure is 0.13MPa.g, the gas phase is hydrogen, and the density of water at this time is ρ=995.676kg / m³. 3 ;

[0230] Step 2: Calculate the primary loop leakage rate (control tank sub-item) based on the liquid level change in the control tank.

[0231] For the M310 unit, the cross-sectional area of ​​the control box is 3.464 m². 2 When the liquid level changes by 1m, the volume changes by 3464L, therefore the correction factor K1 = 3464L / m. The control tank itself has two level gauges (RCV011 / 012MN, unit: cm), and for ease of calculation, K1 = 34.64L / cm. Since the control tank has two level gauges (RCV011 / 012MN), the leakage rate of the control tank is:

[0232] Unit: L / h;

[0233] N11 is the value of the level gauge RCV011MN in the control box when the leakage rate is first calculated, in cm;

[0234] N21 is the value of the RCV011MN level gauge in the control box when the leakage rate calculation is completed, in cm;

[0235] N12 is the value of the level gauge RCV012MN in the control box when the leakage rate is first calculated, in cm;

[0236] N22 is the value of the RCV012MN level gauge in the control box when the leakage rate calculation is completed, in cm;

[0237] △t represents the time interval before and after calculating the leakage rate, in hours (h).

[0238] Step 3: Calculate the primary loop leakage rate (voltage regulator component) based on the change in the total mass of the voltage regulator.

[0239] There is only one voltage regulator in the primary circuit. The voltage regulator is different from the control box. Under normal conditions, the voltage regulator contains both vapor and liquid phases, and the normal pressure is 15.5 MPa.

[0240] Not only does the liquid level affect the water capacity of the pressurizer, but pressure changes leading to steam evaporation / condensation, and changes in the density of steam and saturated water also affect the water capacity. Therefore, calculating the total mass change of the pressurizer requires calculating the total mass before and after the test; refer to the parameter comparison table for saturated water and steam:

[0241]

[0242] The density of saturated water at 15.5 MPa·a can be obtained through interpolation: 594.0416 kg / m³. 3 The density of saturated steam is 101.9430 kg / m³. 3 The density of saturated water changes with pressure at a rate of -18.3495 kg / (m³). 3 The saturated steam density changes with pressure at a rate of 10.7545 kg / (m³). 3 (·MPa);

[0243] Therefore, at a pressure of approximately 15.5 MPa, the density of saturated water can be approximated as:

[0244] ρ′ P =ρ′ 15.5 -18.3495×(P-15.5)=594.0416-18.3495×(P-15.5),

[0245] The pressure of saturated steam can be approximated as:

[0246] ρ″ P =ρ″ 15.5 +10.7545×(P-15.5)=101.9430+10.7545×(P-15.5),

[0247] Since the voltage regulator is a cylinder with a cross-sectional area of ​​2.148 m², 2 That is, when the liquid level changes by 1m, the volume changes by 2148L; the pressure regulator has three liquid level gauges RCP007 / 008 / 011MN and five pressure gauges RCP005 / 006 / 013 / 014 / 015MP.

[0248] Due to the lower limit L of the voltage regulator level gauge 下限 The depth is -6m, therefore the water volume of the pressure regulator is:

[0249]

[0250] The upper limit of the liquid level metering range L of the pressure regulator 上限The volume is 3.8m, therefore the total volume of the gas phase of the voltage regulator is:

[0251]

[0252] Therefore, the water volume before the experiment was:

[0253]

[0254] N31 is the value of the level gauge RCP007MN of the pressure regulator when the leakage rate is first calculated, in meters;

[0255] N32 is the value of the level gauge RCP008MN of the pressure regulator when the leakage rate is first calculated, in meters;

[0256] N33 is the value of the level gauge RCP011MN of the pressure regulator when the leakage rate is first calculated, in meters;

[0257] ρ′1 is the density of saturated water in the voltage regulator calculated before the test, in kg / m³. 3 ;

[0258]

[0259] ρ″1 is the density of saturated steam in the pressure regulator calculated before the test, in kg / m³. 3 ;

[0260]

[0261] P11 is the value of the pressure gauge RCP005MP on the pressure regulator before the test, in MPa.g.

[0262] P12 is the value of the pressure gauge RCP006MP of the pressure regulator before the test, in MPa.g.

[0263] P13 is the value of the pressure gauge RCP013MP on the pressure regulator before the test, in MPa.g.

[0264] P14 is the value of the pressure gauge RCP014MP on the pressure regulator before the test, in MPa.g.

[0265] P15 is the value of the pressure gauge RCP015MP of the pressure regulator before the test, in MPa.g.

[0266] The water volume after the test was:

[0267]

[0268] N41 is the value of the level gauge RCP007MN of the pressure regulator when the leakage rate calculation is completed, in meters;

[0269] N42 is the value of the level gauge RCP008MN of the pressure regulator when the leakage rate calculation is completed, in meters;

[0270] N43 is the value of the level gauge RCP011MN of the pressure regulator when the leakage rate calculation is completed, in meters;

[0271] ρ′2 is the density of saturated water in the voltage regulator calculated after the experiment, in kg / m³. 3 ;

[0272]

[0273] ρ″2 is the density of saturated steam in the pressure regulator calculated after the experiment, in kg / m³. 3 ;

[0274]

[0275] P21 is the value of the pressure gauge RCP005MP of the voltage regulator after the test, in MPa.g.

[0276] P22 is the value of the pressure gauge RCP006MP of the voltage regulator after the test, in MPa.g.

[0277] P23 is the value of the pressure gauge RCP013MP on the voltage regulator after the test, in MPa.g.

[0278] P24 is the value of the pressure gauge RCP014MP after the test, in MPa.g.

[0279] P25 is the value of the pressure gauge RCP015MP of the voltage regulator after the test, in MPa.g.

[0280] Since the measured pressures in the unit are all gauge pressures, the pressure correction value of 15.5 MPa.a when calculating the density of saturated water or saturated steam in the pressurizer is changed to 15.4 MPa.g; where 15.5 MPa is the absolute pressure during reactor operation and 15.4 MPa is the gauge pressure.

[0281] The mass difference Δm before and after the test is:

[0282]

[0283] The calculated leakage rate of the voltage regulator component is: Unit: L / h;

[0284] It should be noted that ρ here refers to the density under the reference temperature and pressure of the controlled-volume chamber, i.e., ρ = 995.676 kg / m³. 3 1000 is for standardizing m 3 The conversion factor to L;

[0285] Step 4: Calculate the primary loop leakage rate (average temperature component) based on the primary loop average temperature change.

[0286] The coolant in the primary loop is unsaturated water. Changes in the average temperature will cause the coolant to expand and contract. This volume change will affect the calculated leakage rate, but it is not the actual leakage of the primary loop. Therefore, this part must be excluded when calculating the leakage rate, i.e., the result of this sub-item calculation is negative. It is worth mentioning that although the primary loop is connected to the voltage regulator, the temperature of the working fluid in the voltage regulator does not change with the average temperature of the primary loop. It is always at the saturation temperature. Therefore, the total volume of the primary loop excluding the voltage regulator can only be calculated.

[0287] The total volume of one circuit, including the voltage regulator, is 199m³. 3 The total volume of the voltage regulator is 21m³. 3 Therefore, the total volume of the primary loop is calculated as V = 199 - 21 = 178 m³. 3 ;

[0288] During full-capacity operation of the M310 unit, the average temperature of the primary circuit ranges from 291.4℃ to 310℃. The water parameters under these conditions are shown in the table below:

[0289] Temperature / °C 285.79 294.97 303.31 310.96 <![CDATA[Specific volume / (m 3 / kg)]]> 0.001351 0.001384 0.001418 0.001453 <![CDATA[Density / (kg / m 3 )]]> 740.0172 722.4129 705.2883 688.4397

[0290] The density of water at different temperatures can be obtained from the differences in the table above:

[0291] ρ 一回路 =740.0172-(T) 一回路 -285.79)×2.0492

[0292] In the formula ρ 一回路 It is the density of the coolant in the primary circuit, T 一回路 It is the average temperature of the primary coolant;

[0293] When the temperature changes, the change in the total volume of the primary loop is:

[0294]

[0295] In the above formula:

[0296] V is the total volume of the primary circuit excluding the voltage regulator, which is 178m³. 3 ;

[0297] ρ is the density of water under standard working conditions, which is 995.676 kg / m³. 3 ;

[0298] ρ 一回路1 The density of the primary coolant before the test is expressed in kg / m³. 3 ;

[0299] ρ 一回路2 The density of the primary coolant after the test is expressed in kg / m³. 3 ;

[0300] T 一回路1 The average temperature of the primary coolant before the test, in °C;

[0301] T 一回路2 The average temperature of the primary coolant after the test, in °C;

[0302] Since the primary loop has three identical loops, each with its own average temperature gauge (RCP611 / 615 / 619KM), the average temperature of the primary loop is the average of the average temperatures of the three loops, that is:

[0303]

[0304] T11 is the value of the average temperature of the primary loop at RCP619KM when the leakage rate is first calculated, in °C;

[0305] T21 is the value of the average temperature of the first loop at RCP619KM when the leakage rate calculation is completed, in °C.

[0306] T12 is the value of the average temperature of the primary loop at RCP611KM when the leakage rate is first calculated, in °C;

[0307] T22 is the value of the average temperature of the first loop at RCP611KM when the leakage rate calculation is completed, in °C.

[0308] T13 is the value of the average temperature of the primary loop at RCP615KM when the leakage rate is first calculated, in °C;

[0309] T23 is the value of the average primary loop temperature RCP615KM at the end of the leakage rate calculation, in °C;

[0310] The leakage rate for the average temperature component is:

[0311] Unit: L / h;

[0312] In the formula, 1000 represents m 3 Convert to L-fold ratio;

[0313] Step 5: Calculate the primary loop leakage rate (water replenishment item) based on the borylation / dilution amount.

[0314] During the calculation of the primary loop leakage rate, if borying / dilution operations are performed on the primary loop, this is actually makeup water for the primary loop. The amount of borying / dilution can be directly read in liters (L). Therefore, the leakage rate for the makeup water item is:

[0315] Unit: L / h;

[0316] Where V 硼化 / 稀释 Boration / dilution amount, in liters (L);

[0317] Step 6: Calculate the primary loop leakage rate (wastewater component) based on the boron recovery system (TEP) level changes.

[0318] The boron recovery system is responsible for collecting leaked coolant from the primary loop. The collected coolant is concentrated in the wastewater head tank, which has a cross-sectional area S3 of 8m². 2 Therefore, the leakage rate of wastewater is:

[0319] Unit: L / h;

[0320] N5 represents the liquid level in the head tank of the boron recovery system before the test, in meters (m).

[0321] N6 is the liquid level in the head tank of the boron recovery system after the test, in meters (m).

[0322] In the formula, m 3 The value was converted to L and then a multiplier was calculated.

[0323] Step 7: Summarize the individual values ​​of the primary loop leakage rate.

[0324] The leakage rate items calculated in steps 2 to 6 are added together to obtain the primary loop leakage rate; the average temperature item should be subtracted from the leakage rate, so it is taken as a negative value.

[0325] Primary loop leakage rate F p for:

[0326]

[0327] Unit: L / h.

[0328] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or basic characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0329] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0330] This invention creatively considers the influence of pressure on the water volume of a pressure regulator with coexisting steam and water, the difference in coolant density in different parts, and the use of multiple similar instruments in coordination, which to a certain extent eliminates the influence of deviation of a single instrument.

[0331] This invention effectively improves the accuracy, precision, and stability of reactor coolant leakage rate calculations. To demonstrate this conclusion, data from 0:30 to 2:00 on January 1, 2023, were selected at 1-minute intervals. Two different leakage rate calculation methods were used to calculate 211 sets of data for each time period, resulting in 91 sets of results (data is shown in the appendix at the end of the specification, with all time intervals being 2 hours). The analysis results are as follows:

[0332] Evaluation methods Average leakage rate (L / h) variance Range Method of the present invention 34.43 157.91 66.13 Existing technical methods 59.92 935.18 126.29

[0333] As can be seen, the leakage rate variance calculated by the method of this invention is reduced by 83.11% and the range is reduced by 47.64% compared with the existing method. In summary, this invention has the following significant advantages:

[0334] (1) The method of the present invention takes into account the influence of pressure change of the pressure regulator on the water loading, and fully analyzes the evaporation and condensation of steam in the pressure regulator, so the calculation results are more accurate;

[0335] (2) The method of the present invention normalizes the influence of changes in various parts on the leakage rate. Based on the actual situation of the unit, the leakage rate of each part is unified as the parameter under the pressure and temperature of the control box, and the calculation result is more accurate.

[0336] (3) The method of the present invention effectively reduces the impact of the accidental error of a single instrument on the leakage rate calculation, the calculation results are more stable, and the efficiency of calculating the normal leakage rate is higher.

[0337] (4) The method of the present invention can effectively reduce the probability and magnitude of unreasonable extreme leakage rate values, and the range of the statistical calculation results is smaller;

[0338] (5) The method of the present invention no longer distinguishes whether boronizing / dilution (water replenishment) is performed during the test, and the leakage rate calculation idea is clearer;

[0339] (6) The formulas involved in the method of the present invention can be prepared by software and used. Only the known values ​​need to be input to immediately obtain the corresponding conversion results, which improves the calculation efficiency, reduces the risk of errors, and facilitates promotion.

[0340] The attached table shows the data selected for the experiment and the leakage rates obtained from the old and new calculation methods.

[0341]

[0342]

[0343]

[0344]

[0345]

[0346]

[0347]

[0348]

Claims

1. A method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant, characterized in that: Consider the leakage rate of the entire primary loop, including the control box, voltage regulator, primary loop water body, boron recovery system head box that receives primary loop wastewater and boron and water supply system that replenishes primary loop water. Includes the following steps: Step 1: Define the standard operating environment for calculating the leakage rate of the primary loop during power operation; Step 2: Calculate the primary loop leakage rate (capacity control box component) based on the liquid level change in the control box; Step 3: Calculate the primary loop leakage rate of the voltage regulator based on the change in the total mass of the voltage regulator; Step 4: Calculate the average temperature component of the primary loop leakage rate based on the change in the primary loop average temperature; Step 5: Calculate the primary loop leakage rate water replenishment item based on the borylation / dilution amount; Step 6: Calculate the primary loop leakage rate and wastewater percentage based on the boron recovery system level changes; Step 7: Summarize the values ​​of each component of the primary loop leakage rate to obtain the primary loop leakage rate; In step 1, the working environment of the control box is taken as the standard working environment; In step 3, considering that not only the liquid level affects the water level in the pressure regulator, but also pressure changes leading to steam evaporation or condensation, and changes in the density of steam or saturated water, the water level before the test is: N31, N32, and N33 are the values ​​of the three level gauges of the pressure regulator when the leakage rate is first calculated, in meters (m). S2 is the cross-sectional area of ​​the voltage regulator, in meters (m²). 2 ; L 下限 This is the lower limit of the range of the level gauge for the pressure regulator, in meters (m). L 上限 The upper limit of the level gauge range for the pressure regulator, in meters (m). Interpolation revealed that the density of saturated water at 15.5 MPa·a is 594.0416 kg / m³. 3 The density of saturated steam is 101.9430 kg / m³. 3 The density of saturated water changes with pressure at a rate of -18.3495 kg / (m³). 3 The saturated steam density changes with pressure at a rate of 10.7545 kg / (m³). 3 (·MPa); ρ′1 is the density of saturated water in the voltage regulator calculated before the test, in kg / m³. 3 , ρ″1 is the density of saturated steam in the pressure regulator calculated before the test, in kg / m³. 3 , P11, P12, P13, P14, and P15 are the values ​​of the five pressure gauges on the voltage regulator before the test, in MPa.g. The water volume after the test was: N41, N42, and N43 are the values ​​of the three level gauges of the pressure regulator when the leakage rate calculation is completed, in meters (m). ρ′2 is the density of saturated water in the voltage regulator calculated after the experiment, in kg / m³. 3 , ρ″2 is the density of saturated steam in the pressure regulator calculated after the experiment, in kg / m³. 3 , P21, P22, P23, P24, and P25 are the values ​​of the five pressure gauges on the voltage regulator after the test, in MPa.g. 15.4 is the measured value of the unit gauge pressure when calculating the density of saturated water or saturated steam in the pressurizer, used as a pressure correction value, in MPa.g; The mass difference Δm before and after the test is: Δm=m 试验后 -m 试验前 , The leakage rate of the voltage regulator component is: Unit: L / h; △t represents the time interval before and after calculating the leakage rate, in hours (h). ρ is the density of water under standard working conditions, in kg / m³. 3 .

2. The method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant as described in claim 1, characterized in that: In step 2, considering the impact of changes in the liquid level in the control tank on the primary loop leakage rate, the leakage rate of the control tank component is: Unit: L / h; S1 is the cross-sectional area of ​​the control box, in m². 2 ; N11 and N12 are the values ​​of the two level gauges in the control box when the leakage rate is first calculated, in cm; N21 and N22 are the values ​​of the two level gauges in the control box when the leakage rate calculation is completed, in cm.

3. The method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant as described in claim 1, characterized in that: In step 4, the leakage rate of the average temperature component is: Unit: L / h; V is the total volume of the primary circuit excluding the voltage regulator, in meters. 3 ; T11, T12, and T13 are the values ​​of the three average temperature gauges in the primary loop at the beginning of the leakage rate calculation, in °C. T21, T22, and T23 are the average temperature values ​​of the three thermometers in the primary loop when the leakage rate calculation is completed, in °C.

4. The method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant as described in claim 1, characterized in that: In step 5, if borylation / dilution is performed on the primary loop during the calculation of the primary loop leakage rate, it is actually a water replenishment operation on the primary loop, and the amount of borylation / dilution can be read directly. The leakage rate of the water replenishment item is: Unit: L / h; Where V 硼化 / 稀释 The amount of boronization / dilution is expressed in liters (L).

5. The method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant as described in claim 1, characterized in that: In step 6, the boron recovery system is responsible for collecting the leaked coolant from the primary loop. The collected coolant is concentrated in the wastewater head tank; therefore, the leakage rate of the wastewater is: Unit: L / h; S3 is the cross-sectional area of ​​the wastewater head tank, in meters (m²). 2 ; N5 represents the liquid level in the head tank of the boron recovery system before the test, in meters (m). N6 represents the liquid level in the head tank of the boron recovery system after the test, in meters (m).

6. The method for calculating the reactor coolant leakage rate of a pressurized water reactor nuclear power plant as described in claim 1, characterized in that: In step 7, the leakage rate items calculated in steps 2 to 6 are added together to obtain the primary loop leakage rate F. p .

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