Method for calculating the amount of tracer used for steam generator humidity measurement test

Abstract

The present application relates to a kind of for the amount of tracer of steam generator humidity measurement test calculation method, comprising the following steps: S1, determine the background mass of tracer element X in the steam generator;S2, determine the detection limit of the tracer element X;S3, according to the detection limit of the tracer element X and the water quality limit of the steam generator, determine the dose of the tracer element X;S4, according to the background mass of the tracer element X in the steam generator and the dose of the tracer element X, calculate the amount of the tracer range.The present application utilizes the boundary value provided by the humidity measurement test calculation principle and the limit condition of unit operation, accurately calculates tracer dose;Can accurately calculate the amount of tracer required for humidity test in the case of reducing the risk of water quality exceeding standard, can solve the amount of tracer of different components, also can solve the amount of tracer of new unit, especially short time repeatedly executed humidity measurement test.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear power technology, and in particular to a method for calculating the amount of tracer used in a steam generator humidity measurement test. BACKGROUND

[0002] A nuclear power plant is mainly composed of a reactor, a primary system and a secondary system. Nuclear fission occurs in the reactor core composed of nuclear fuel, and the heat released by nuclear fission is taken out of the reactor by high-pressure water flowing through the core and is transferred to the water in the secondary system in the steam generator. The steam generated by the heated water drives the steam turbine, which in turn drives the generator to generate electricity.

[0003] The steam generator humidity measurement test is a key unit performance test, and the test results will directly reflect the steam quality at the outlet of the steam generator. The tracer method is usually used to measure the steam humidity of a nuclear power unit, and the test principle is to inject a certain amount of tracer that is easily soluble in water and insoluble in gas into the secondary system, and to obtain the steam humidity before the flow limiter of the steam generator by using ion trace detection technology. In the humidity test, the amount of tracer used not only determines the test results, but also affects the safe operation of the unit. In particular, when the humidity measurement needs to be repeated in a short time, the dose of the tracer needs to be accurately calculated.

[0004] The amount of tracer in the related art is mainly referred to the power station, and this amount is only applicable to the same type of steam generator unit. The amount of tracer for nuclear power units with different technical routes and different types of steam generators needs to be accurately calculated. In addition, the tracer selected in the related technical solution is generally limited, and if it is replaced, the dose of the tracer also needs to be adjusted. Moreover, the related technology cannot meet the demand of multiple humidity measurement tests in a short time, and the problem is the amount of tracer used during repeated tests. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a method for calculating the amount of tracer used in a steam generator humidity measurement test, which is accurate and has universal applicability, in view of the defects of the prior art.

[0006] The technical solution adopted by the present application to solve the technical problem is: a method for calculating the amount of tracer used in a steam generator humidity measurement test is constructed, comprising the following steps:

[0007] S1, determining the background mass m of the tracer element X in the steam generator X-0 ;

[0008] S2, determining the detection limit C of the tracer element X LQD-X ;

[0009] S3, determining the minimum dose m of the tracer element X according to the detection limit C of the tracer element X and the water quality limit value of the steam generator; LQD-X and the dose of the tracer element X, calculating the dosage range of the tracer.

[0010] S4, determining the background mass m of the tracer element X in the steam generator according to the detection limit C of the tracer element X X-0 and the dose of the tracer element X, calculating the dosage range of the tracer.

[0011] Preferably, the background mass m of the tracer element X in the steam generator before the test is determined according to the concentration of the tracer element X in the steam generator before the test, the detection limit C of the tracer element X, and the water quality limit value of the steam generator. X-0 calculated by formula (1):

[0012]

[0013] wherein, i = 1, 2…; C X-0 is the concentration of the tracer element X in the steam generator before the test, with the unit of ppb; m SG-water is the water load during normal operation of a single steam generator, with the unit of t.

[0014] Preferably, the step S2 specifically comprises:

[0015] S21, determining the composition of the tracer;

[0016] S22, determining the detection limit C of the tracer element X according to the ion concentration detection device and detection method LQD-X .

[0017] Preferably, the step S22 specifically comprises:

[0018] determining the detection limit C of the tracer element X according to the ion concentration detection device and detection method LQD-X .

[0019] Preferably, the detection device is a mass spectrometer.

[0020] Preferably, the step S3 specifically comprises:

[0021] S31, determining the minimum dose m of the tracer element X according to the detection limit C of the tracer element X and the water quality limit value of the steam generator; LQD-X . X-min

[0022] S32, determining the maximum dose m of the tracer element X according to the water quality limit value X-max .

[0023] Preferably, the step S31 specifically comprises:

[0024] according to the design humidity M of the steam generator outlet design and the detection limit C of the tracer element X LQD-X ​, the minimum dose m of the tracer element X is calculated X-min .

[0025] Preferably, the minimum dose m of the tracer element X is calculated X-min The minimum dose m of the tracer element X is calculated by formula (2):

[0026]

[0027] Preferably, the step S32 specifically comprises:

[0028] The maximum dose m of the tracer element X is calculated by converting the solution sodium concentration limit of the secondary side of the steam generator into the tracer element concentration under the same molar concentration, using the water quality limit as the maximum dose of the tracer. X-max .

[0029] Preferably, the maximum dose m of the tracer element X is calculated X-max The maximum dose m of the tracer element X is calculated by formula (3):

[0030]

[0031] Wherein, C limit-Na is the allowed sodium ion concentration of the steam generator, with the unit of ppb; A X is the relative atomic mass of the tracer element X; A Na is the relative atomic mass of the sodium element; N is the number of steam generators.

[0032] Preferably, the dosage range of the tracer is calculated by formula (4):

[0033]

[0034] Wherein, k is the proportion of the tracer element X in the tracer, with the unit of %.

[0035] The present application has the following beneficial effects: the present application accurately calculates the dosage of the tracer by using the boundary values provided by the humidity measurement test calculation principle and the operating limit conditions of the unit; the present application can accurately calculate the dosage of the tracer required by the humidity test while reducing the risk of water quality exceeding the standard, and can solve the problem of the dosage of the tracer with different components, and can also solve the problem of the dosage of the tracer for the humidity measurement test of the new unit, especially the short-time repeated execution. BRIEF DESCRIPTION OF DRAWINGS

[0036] The present application will be further described below in combination with the drawings and examples, and the drawings are as follows:

[0037] Figure 1 is the flowchart of the dosage calculation method of the tracer for the humidity measurement test of the steam generator of the present application;

[0038] Figure 2 is a flow chart of step S2 of the method for calculating the amount of tracer used in the steam generator humidity measurement test of the present application;

[0039] Figure 3 is a flow chart of step S3 of the method for calculating the amount of tracer used in the steam generator humidity measurement test of the present application. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will now be described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "upper", "lower", "left", "right", "vertical", "horizontal", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail" and the like are based on the directions or positional relationships shown in the drawings, constructed and operated in a particular direction, and are only for the convenience of describing the technical solutions, and should not be construed as indicating that the devices or elements referred to must have a particular direction. Therefore, it should not be understood as a limitation on the present application.

[0041] It should also be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing", "setting" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there can be one or more intervening elements. The terms "first", "second", "third" and the like are only for the convenience of describing the technical solutions, and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features with "first", "second", "third" and the like can be explicitly or implicitly included one or more of the features. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] In the following description, specific details such as specific system structures, techniques, etc. are presented in order to facilitate a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits and methods are omitted to avoid unnecessary details that hinder the description of the present application.

[0043] Currently, most of the technical solutions selected for steam generator humidity measurement test are as follows: 160g-180g tracer is used. During the test, the tracer solution is injected into the secondary loop by using the negative pressure before the condensate pump, and after the tracer is stably circulated in the secondary loop, the steam humidity is calculated by measuring the ion concentration of the tracer element in the main feed water and the steam generator water sample. The amount is only suitable for the same type of steam generator unit. In view of this, the present application provides a nuclear power unit which can be applied to different types of steam generators, and can be quantitatively calculated for different amounts of tracers.

[0044] As Figure 1 shown, it is a tracer dosage calculation method for steam generator humidity measurement test of the present application, which can accurately calculate the required dosage of the tracer, and the scheme is suitable for the dosage calculation of different tracers, and has certain universality. The method comprises the following steps:

[0045] S1, determining the background mass m of the tracer element X in the steam generator X-0 The background mass of the tracer element X in the steam generator refers to the mass of the tracer element already contained in the steam generator environment before the tracer is added. Since the tracer injected during the steam generator humidity measurement test will remain in the secondary loop of the unit, the uncertainty caused by the background residue after the test, therefore, the background concentration of the steam generator water sample needs to be measured before the steam generator humidity measurement test is performed. This step needs to be obtained after the actual water sample in the field steam generator is measured before the formal test, the purpose is to eliminate the influence of the remaining tracer element in the environment on the test concentration. Generally, this operation is performed one day before the formal test. Understandably, the steps in the present application are generally prepared before the test, therefore, the execution order of the steps can be adjusted according to the actual situation.

[0046] Further, the background mass m of the tracer element X in the steam generator before the test is calculated by formula (1): X-0

[0047]

[0048] Wherein, i=1, 2…; N=1, 2…; C X-0 is the concentration of the tracer element X in the steam generator before the test, and the unit is ppb; m SG-water is the water load of a single steam generator during normal operation, and the unit is t.

[0049] S2, determining the detection limit C LQD-X of the tracer element X;

[0050] Further, as Figure 2 shown, step S2 specifically comprises:

[0051] ​S21, determining the chemical composition of the tracer; this step is determined by the tester before the test, and the tracer can be selected from compounds of lithium, sodium, potassium and cesium, such as lithium hydroxide, cesium carbonate, cesium chloride and the like. For example, the tracer element X is selected as lithium or cesium.

[0052] S22, determining the detection limit C of the tracer element X in the tracer LQD-X . Further, step S22 specifically includes determining the detection limit C of the tracer element X according to the ion concentration detection device and the detection method LQD-X . Specifically, the detection limit of the corresponding element can be obtained according to the device using element analysis. In this embodiment, the detection device used can be a mass spectrometer. The working principle of the mass spectrometer is as follows: first, the ion concentration and count rate curve of the tracer element X is obtained by detecting standard tracer solutions with different concentrations using the detection device, so as to obtain the ion concentration of the tracer element X to be detected according to the curve and the count rate of the tracer solution to be detected, and further determine the detection limit C of the tracer element X LQD-X . Ion concentration detection usually uses an ICP-MS inductively coupled plasma mass spectrometer to detect the concentration of tracer elements in representative samples. The detection method mainly includes the following steps: using laboratory high-purity water as a standard blank, using the test element standard solution and laboratory high-purity water to prepare a plurality of standard samples to form a standard sample curve, and sampling in the order of "standard blank→standard sample→sample to be tested" to obtain the concentration detection result of the tracer element in the sample to be tested.

[0053] S3, determining the dose of the tracer element X according to the detection limit C LQD-X of the tracer element X and the water quality limit of the steam generator;

[0054] Further, as shown in Figure 3 , step S3 specifically includes:

[0055] S31, determining the minimum dose m LQD-X of the tracer element X according to the detection limit C X-min of the tracer element X;

[0056] Further, step S31 specifically includes:

[0057] calculating the minimum dose m X-min of the tracer element X according to the detection limit C LQD-X of the tracer element X and the design humidity M design of the steam generator outlet. In order to ensure the long-term normal operation of the steam turbine, the design humidity M design of the steam generator outlet is generally not more than 0.1%, and the design humidity M designis one of the performance guarantee parameters of the steam generator itself, and can be directly obtained from the relevant design documents of the steam generator.

[0058] Specifically, the minimum dose m X-max calculated from formula (2):

[0059]

[0060] wherein C LQD-x is the detection limit of the tracer element X, in ppb; M design is the design humidity at the outlet of the steam generator, in %; m SG-water is the water charge during normal operation of a single steam generator, in t.

[0061] S32, determining the maximum dose m X-max of the tracer element X according to the water quality limit. After the tracer is injected, most of the tracer is enriched in the steam generator, causing the water quality on the secondary side of the steam generator to deteriorate. During the operation of the nuclear power plant, the water quality on the secondary side of the steam generator needs to be strictly controlled, and the deterioration of the water quality will cause the unit state to be withdrawn, affecting the safe operation of the unit. Therefore, the water quality limit can be used as the maximum dose of the tracer.

[0062] Further, step S32 specifically comprises:

[0063] Using the water quality limit as the maximum dose of the tracer, the sodium concentration limit of the solution on the secondary side of the steam generator is converted into the concentration of the tracer element under the same molar concentration, and the maximum dose m X-max of the tracer element X is calculated. According to the chemical technical specification, there are two indexes for the water quality control on the secondary side of the steam generator, which are the positive conductivity and the sodium ion.

[0064] As shown in Table 1, Table 1 is the simulation experiment result of the influence amount of the positive conductivity by different concentrations of tracer solution during the execution of a certain unit. The content of the simulation test of the influence amount of the positive conductivity by different concentrations of cesium carbonate is to configure different concentrations of tracer solution and measure the positive conductivity of the solution. The experimental process is as follows: the tracer solution selected is cesium carbonate, and different concentrations of cesium carbonate are set; take the water sample in the running steam generator and configure it into a cesium carbonate solution with a concentration of 300 ppb, a cesium carbonate solution with a concentration of 600 ppb, and a cesium carbonate solution with a concentration of 1000 ppb, and measure the positive conductivity of the above different concentration solutions respectively. The statistical results are shown in Table 1 below;

[0065] Table 1

[0066]

[0067] The control value of the positive conductivity of the unit is 4-10 μs / cm, and the control range of the positive conductivity of the secondary water quality of the steam generator at home and abroad is basically the same. In summary, it can be seen that the injection of the tracer causes a very small amount of change in the positive conductivity, and compared with the control interval of the power station positive conductivity, the margin is sufficient. Therefore, the positive conductivity limit is not used as the basis for calculating the maximum dose of the tracer.

[0068] Since the available tracer element and the sodium element belong to the same group element, according to the chemical technical specification of the power plant, the sodium concentration limit of the secondary side solution of the steam generator can be converted into the tracer element concentration under the same molar concentration. Specifically, the maximum dose m X-max The conversion calculation is obtained from formula (3):

[0069]

[0070] Wherein, C limit-Na is the allowable sodium ion concentration of the steam generator in the chemical operation technical specification of the power plant, and the unit is ppb; A X is the relative atomic mass of the tracer element X; A Na is the relative atomic mass of the sodium element; m SG-water is the water load during normal operation of a single steam generator, and the unit is t; N is the number of steam generators. It can be understood that the water quality changes according to the state of the unit at any time. The chemical control needs to regulate a number of limits, which divide a number of regions, and the water quality has different management and control requirements in different regions. C limit-Na is actually the target expected value, which is expected to reach at the end of the test.

[0071] S4, according to the background mass m X-0 of the tracer element X in the steam generator and the dose of the tracer element X, the amount range of the tracer is calculated. The dose of the tracer element X includes the maximum dose m X-max of the tracer element X and the minimum dose m X-min of the tracer element X.

[0072] Further, according to the calculation results of the above steps, and by formula (4), the amount range of the selected tracer is:

[0073]

[0074] Wherein, m X-min is the minimum dose of the tracer element X, and the unit is g; m X-max is the maximum dose of the tracer element X, and the unit is g; m X-0 is the background mass of the tracer element X in the steam generator, and the unit is g; k is the proportion of the tracer element X in the tracer, and the unit is %.

[0075] In one embodiment, step S2 involves first determining the detection limit C of the tracer element X. LQD-X Further, step S21 is implemented to determine the composition of the tracer. Based on the actual situation, Cs₂CO₃ is used; therefore, in this embodiment, the tracer element X is cesium. Step S22 is then implemented to determine the detection limit C of the tracer element Cs based on the ion concentration detection equipment and detection method. LQD-X Specifically, the detection limit C of the tracer element Cs was determined based on the detection equipment ICP-MS and the ion concentration measurement method. LQD-X It is 0.1 ppb, where 1 ppb = 1 μg / kg.

[0076] Next, in step S31, the design humidity M at the steam generator outlet can be obtained from the steam generator design documents. design The water loading rate during normal operation of a single steam generator is 0.1% (m³). SG-water The minimum dosage m of the tracer element Cs in the tracer is calculated according to equation (2) and is 70t. X-min :

[0077]

[0078] Substituting the above data into equation (2), we get...

[0079] m X-min =[0.1 / 0.1%]*70*1000 / 1000000=7g;

[0080] Then, proceed to step S3: according to the chemical operation technical specifications, the permissible sodium ion concentration C of the steam generator... limit-Na The value is 95 ppb. With three steam generators, the maximum usable dose (m) of the secondary-side tracer element Cs in the steam generators can be calculated. X-max :

[0081]

[0082] Substituting the above data into equation (3), we get

[0083] m X-max =(95*133*70*1000*3) / (23*1000000)=115.36g;

[0084] Furthermore, in step S1, the background mass m of the tracer element X in the steam generator is determined. X-0 Understandably, this step can also be performed before step S2 in this embodiment without affecting the overall calculation. Specifically, if the background concentration of tracer element Cs before the experiment is 0.1 ppb, then the background mass of tracer element Cs is calculated as follows:

[0085]

[0086] Substitute the above data into formula (3) to obtain

[0087] m X-0 = (0.1 * 70 * 1000 * 3) / 1000000 = 0.021 g;

[0088] Finally, implement step S4, calculate the dosage range of the tracer according to the background mass m X-0 and the dose of the tracer element X in the steam generator. Wherein, the proportion of the tracer element Cs in the tracer needs to be determined first, and the proportion k of the tracer element Cs in the tracer is calculated as follows:

[0089] The compound in this embodiment is cesium carbonate Cs2CO3, so the mass number of the compound is:

[0090] 133 (Cs) * 2 + 12 (C) + 16 (O) * 3 = 326;

[0091] Therefore, the proportion k of cesium element in the compound is k = (133 * 2) / 326 = 81.6%;

[0092] Accordingly, substitute the relevant parameters into formula (4),

[0093]

[0094] Finally, the dosage range of cesium carbonate tracer is as follows:

[0095] [(7-0.021) / 81.6%, (115.36-0.021) / 81.6%] = [8.55, 141.35] g;

[0096] That is, in this embodiment, the dosage range of cesium carbonate tracer is [8.55, 141.35] g. Since the tracer is injected into the secondary circuit, the tracer will be enriched in the steam generator, and the amount of tracer remaining in the steam-water circulation loop is negligible, so the tracer remaining in the steam-water circulation loop is ignored in this embodiment.

[0097] Understandably, the method of the present application is not limited to the dosage calculation of cesium carbonate as a tracer, but also applies to the dosage calculation of other tracers, which will not be repeated here.

[0098] The present application uses the boundary values provided by the humidity measurement test calculation principle and the operation limit conditions of the unit to accurately calculate the tracer dosage, obtains the minimum dosage of the tracer according to the design humidity of the steam generator outlet and the detection limit of the tracer element, and uses the water quality limit as the maximum usage dosage of the tracer; the tracer dosage required by the humidity test can be accurately calculated in the case of reducing the risk of exceeding the water quality, the tracer dosage of different components can be solved, and the tracer dosage of the humidity measurement test of the new unit, especially the short-time repeated execution, can also be solved.

[0099] It can be understood that the above embodiments only express the preferred embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application; it should be pointed out that for ordinary skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and a number of modifications and improvements can be made, which belong to the protection scope of the present application; therefore, any equivalent transformation and modification within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A method for calculating the dosage of tracer used in a humidity measurement test of a steam generator, characterized in that, Includes the following steps: S1. Determine the background mass of tracer element X in the steam generator. ; S2. Determine the detection limit of the tracer element X. ; S3. Based on the detection limit of the tracer element X. The dosage of tracer element X is determined based on the water quality limit of the steam generator. S4. Based on the background mass of the tracer element X in the steam generator. Calculate the dosage range of the tracer based on the dose of the tracer element X; Step S3 specifically includes: S31, Based on the design humidity of the steam generator outlet and the detection limit of the tracer element X Calculate the minimum dose of the tracer element X. ; The minimum dose of the tracer element X Calculated from equation (2): Equation (2); In the formula, The water volume during normal operation of a single steam generator; S32. Using the water quality limit as the maximum dose of the tracer, the sodium concentration limit of the secondary side solution of the steam generator is converted into the tracer element concentration at the same molar concentration, and the maximum dose of the tracer element X is calculated. ; The maximum dose of the tracer element X Calculated from equation (3): Equation (3); in, The permissible sodium ion concentration for the steam generator is expressed in ppb. The relative atomic mass of tracer element X; is the relative atomic mass of sodium; This refers to the number of steam generators.

2. The method for calculating the amount of tracer used in the humidity measurement test of a steam generator according to claim 1, characterized in that, The background mass of tracer element X in the steam generator described before the experiment Calculated from equation (1): Equation (1); Where i = 1, 2, ...; The concentration of tracer element X in the steam generator mentioned before the experiment is expressed in ppb. The water volume during normal operation of a single steam generator is expressed in tons (t).

3. The method for calculating the amount of tracer used in the humidity measurement test of a steam generator according to claim 1, characterized in that, Step S2 specifically includes: S21. Determine the composition of the tracer; S22. Determine the detection limit of tracer element X in the tracer. .

4. The method for calculating the amount of tracer used in the humidity measurement test of a steam generator according to claim 3, characterized in that, Step S22 specifically includes: The detection limit of the tracer element X was determined based on the ion concentration detection equipment and method. .

5. The method for calculating the amount of tracer used in the humidity measurement test of a steam generator according to claim 4, characterized in that, The detection equipment is a mass spectrometer.

6. The method for calculating the amount of tracer used in the humidity measurement test of a steam generator according to claim 1, characterized in that, The dosage range of the tracer is calculated using equation (4): Equation (4); in, The percentage of the tracer element X in the tracer is expressed in units of %.

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