Solid-state heat pipe reactor core temperature distribution monitoring method

Abstract

The invention discloses a method for monitoring temperature distribution of a reactor core of a solid-state heat pipe reactor. The method comprises a scheme of arranging thermocouples in a fuel assembly, and a method for acquiring local temperature data in real time by utilizing the thermocouples and inverting three-dimensional temperature distribution. Fuel rods and heat pipes in the assembly are arranged in a hexagonal array mode, in order to achieve the purpose of monitoring the temperature of the whole assembly, a measuring hole channel of a thermocouple is formed in the center of a triangular area formed by every three heat pipes, and the local temperature measurement value of a base body around the measuring hole channel is obtained; the average temperature of a matrix and the temperature of a measurement channel are obtained based on the assembly power of online calculation of a reactor core, and three-dimensional temperature distribution in the reactor is obtained by utilizing three-dimensional data inversion reconstruction. The method can be used for monitoring the state change of the reactor core and implementing safety protection.

Description

Technical Field

[0001] The invention relates to the field of nuclear reactor core design and safety technology, and in particular to a method for monitoring temperature distribution in a solid-state heat pipe reactor core. Background Art

[0002] The heat pipe reactor is a new type of nuclear reactor based on the heat pipe heat exchange principle. It adopts a solid core design concept and transfers fission heat to the heat pipe through the matrix by heat conduction. The above characteristics of the heat pipe reactor determine that it is impossible to monitor the core thermal parameters through traditional methods such as outlet temperature and flow rate. Instead, it is necessary to monitor the temperature distribution in the reactor to ensure the safe operation of the reactor.

[0003] Due to the characteristics of the core structure of the heat pipe reactor, it is impossible to arrange dense sampling points in the reactor to directly measure the three-dimensional temperature distribution. Instead, the temperature distribution of the entire reactor core can only be inverted through limited temperature measurement points. Limited by the solid matrix, the influence of local power changes in the component on the temperature distribution in the surrounding area is limited. In order to achieve the reconstruction of the temperature distribution, it is necessary to reasonably arrange the measurement points in the component, and then reconstruct the three-dimensional distribution through algorithms on this basis. At present, there is no effective solution to the above problems. Therefore, it is of great significance to propose a temperature distribution monitoring technology suitable for the solid-state core of the heat pipe reactor and develop a targeted core temperature monitoring system for the safe operation of the heat pipe reactor. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for monitoring the core temperature distribution of a solid-state heat pipe reactor. By combining the design of a temperature measurement point arrangement scheme with online calculation and data inversion, the three-dimensional temperature field distribution can be reconstructed in real time to realize core temperature distribution monitoring.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for monitoring the core temperature distribution of a solid-state heat pipe reactor comprises: a scheme for arranging fuel rods, heat pipes and thermocouples in the core and a reconstruction technology used for online monitoring of temperature changes using thermocouple temperature changes, specifically: a hexagonal fuel assembly is arranged in the core of the solid-state heat pipe reactor, and the fuel rods and heat pipes in the hexagonal fuel assembly are arranged in a hexagonal array. To achieve the purpose of temperature monitoring of the entire assembly, a measurement channel equipped with a thermocouple is arranged at the center of a triangular area formed by every three heat pipes to obtain a local temperature measurement value of a substrate around the measurement channel; to monitor the core temperature change in real time, the average power of the hexagonal fuel assembly and the average temperature of the substrate around the measurement channel are calculated online by a nuclear design program, and the temperature distribution of the core is obtained in combination with a reconstruction technology based on local temperature measurement data.

[0007] Fuel rods, measuring channels and heat pipes are classified according to their relative positional relationships, and corresponding data reconstruction algorithms are used to reconstruct the three-dimensional temperature field of areas corresponding to different relative positional relationships.

[0008] Classification is carried out according to the relative position relationship of the fuel rod, the measuring channel and the heat pipe. Specifically, classification is carried out according to the arrangement of the components and the position characteristics of the points to be measured. There are four categories in total, namely: the first characteristic temperature point is the temperature of the substrate between the measuring channel and the fuel rod; the second characteristic temperature point is the temperature of the substrate between two fuel rods; the third characteristic temperature point is the temperature of the substrate between the fuel rod and the heat pipe; the fourth characteristic temperature point is the temperature of the substrate between the measuring channel and the heat pipe; different data reconstruction methods are used for characteristic temperature points at different positions;

[0009] (1) The first and second characteristic temperature points are adopted as follows:

[0010] Calculate the distance between any two known data points:

[0011]

[0012] Where: x i ,x j Represents the horizontal coordinate of the known data point, y i ,y j Represents the ordinate of a known data point, d ij Represents the distance between any two data points;

[0013] The distance matrix is ​​formed and the matrix is ​​transformed as follows:

[0014]

[0015] Get a new matrix J:

[0016]

[0017] Calculate the value of the measured data point and the obtained weight vector ω to obtain the first and second characteristic temperature point values

[0018] T(x,y)=rω=r·J -1 S=r·J -1 ·[s 1 ,s 2 ,s 3 ,…,s k ] T

[0019] Where: x, y represent the horizontal and vertical coordinates of the data points to be measured; T(x, y) represents the first and second characteristic temperature point values; J is the distance matrix of known data points; r is the distance matrix formed by the data points to be measured and the known data points; ω is the weight vector; S is the temperature value matrix of the known data points; s 1 ~s k is the temperature of the known data point;

[0020] (2) The third and fourth types of characteristic temperature points are adopted as follows:

[0021] T i (x i ,y i )=a 1 (y i 3 -3x i 2 y i )+a 2 (x i 2 +y i 2 )+a 3 (y i 2 -x i 2 )+a 4 x i y i +a 5 x i +a 6 y i +a 7

[0022] Among them: a 1 ~a 7 is the coefficient of the equation; x i Represents the horizontal coordinate of the known data point, y i Represents the ordinate of a known data point; T i (x i ,y i ) represents the temperature value of a known data point;

[0023] Substitute the horizontal and vertical coordinates (x i ,y i ), that is, we get 7 equations, which can be expressed as follows:

[0024]

[0025] In order to calculate the coefficients of the unknowns, the coefficient matrix is ​​inverted and the above formula is transformed into:

[0026]

[0027] Substitute the horizontal and vertical coordinates of the point to be measured to obtain the temperature value of the point to be measured

[0028] T(x,y)=a 1 (y 3 -3x 2 y)+a 2 (x 2 +y 2 )+a 3 (y 2 -x 2 )+a 4 xy+a 5 x+a 6 y+a 7

[0029] Where: x, y represent the horizontal and vertical coordinates of the data point to be measured; T(x, y) represents the temperature value of the data point to be measured.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. The arrangement method proposed in the present invention can realize the measurement in the temperature measurement channel.

[0032] The signal maximizes the acquisition of core temperature information of the heat pipe reactor, so that limited measurement data can characterize the temperature change characteristics of each area of ​​the heat pipe reactor;

[0033] 2. The data inversion method proposed in this invention can achieve the goal of

[0034] The purpose of the high-precision prediction of the three-dimensional temperature distribution of the core is to solve the problem that the traditional method cannot provide temperature monitoring data with sufficient accuracy due to the limited space inside the heat pipe stack and the small number of measurement points. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0036] Figure 1 It is a flow chart of the method of the present invention.

[0037] Figure 2 This is a schematic diagram of a heat pipe reactor core.

[0038] Figure 3 It is a radial schematic diagram of the fuel assembly. DETAILED DESCRIPTION

[0039] like Figure 1 The method process flow chart of the present invention is a method for monitoring the core temperature distribution of a solid-state heat pipe reactor of the present invention, comprising the following steps:

[0040] Step 1: Arrange thermocouples at designated locations. Heat pipe reactor core layout is as follows: Figure 2 As shown in the figure, the heat pipe nuclear reactor is mainly composed of the core, reflector, control rods and shielding system. The heat pipe nuclear reactor has a symmetrical structure and is located in the center of the reactor. The fuel rods are made of UO with mature technology, good data integrity and balanced key performance indicators. 2 Fuel. The selection of cladding materials needs to consider the manufacturing process, high temperature resistance and radiation resistance, structural stability, compatibility with fuel, etc. In the radial direction of the fuel rod, the fuel rod consists of fuel core blocks, air gaps, inner cladding and outer cladding. The core block diameter is 17.2mm, the inner diameter of the fuel cladding is 17.4mm, the outer diameter of the fuel cladding is 19mm, and the fuel cladding material is 15-15Ti. In order to reduce the leakage of neutrons from the core, beryllium oxide (BeO) reflective layers with the advantages of dense and stable structure, high strength, good thermal stability and good performance are arranged at the upper and lower ends of the fuel rods.

[0041] like Figure 3 As shown in the figure, the core of the heat pipe reactor is arranged with 30 fuel assemblies, each of which consists of 30 fuel rods, 19 heat pipes and 6 thermocouples. The fuel rods and heat pipes in the fuel assembly are arranged in a traditional hexagonal array, which is divided into 5 circles from the inside to the outside. In order to achieve the purpose of temperature monitoring of the entire assembly, a measurement channel equipped with a thermocouple is arranged at the center of the triangle formed by every 3 heat pipes to obtain local temperature measurement values.

[0042] Step 2: Obtain temperature field thermocouple data. Based on the principle of thermal radiation, let the temperature inside the measuring channel represent the temperature of the substrate on the outer surface of the measuring channel, that is, obtain the substrate temperature at the specified point. Since the thermocouple works online continuously, the real-time temperature data at the specified location can be obtained;

[0043] Steps 3 and 4: Calculate the power of the component and the average temperature of the component base online. The average power of the component is calculated online through the nuclear design program that matches the heat pipe stack, and then the average temperature of the base around the measurement channel is obtained by combining thermal calculations;

[0044] Step 5: Process the temperature field data matrix. First, classify the fuel rods, measurement channels, and heat pipes according to their relative positional relationships, and use different data reconstruction algorithms to reconstruct the three-dimensional temperature field for areas corresponding to different relationships, such as Figure 3In the relative position relationship, according to the arrangement of the fuel assembly and the position characteristics of the measured points, there are four categories: the first characteristic temperature point is the temperature of the matrix between the measuring channel and the fuel rod; the second characteristic temperature point is the temperature of the matrix between two fuel rods; the third characteristic temperature point is the temperature of the matrix between the fuel rod and the heat pipe; the fourth characteristic temperature point is the temperature of the matrix between the measuring channel and the heat pipe. Different data processing methods are used for characteristic temperature points at different positions. The average matrix temperature is combined with the local temperature measurement data to reconstruct the temperature distribution of the core.

[0045] (1) The first and second characteristic temperature points are adopted as follows:

[0046] Calculate the distance between any two known data points:

[0047]

[0048] Where: x i ,x j Represents the horizontal coordinate of the known data point, y i ,y j Represents the ordinate of a known data point, d ij Represents the distance between any two data points;

[0049] Form a distance matrix and transform the matrix as follows to obtain a new matrix J

[0050]

[0051] Calculate the value of the interpolation point to be measured and the obtained weight vector ω to obtain the first and second characteristic temperature point values

[0052] T(x,y)=rω=r·J -1 S=r·J -1 ·[s 1 ,s 2 ,s 3 ,…,s k ] T

[0053] Where: x, y represent the horizontal and vertical coordinates of the data points to be measured; T(x, y) represents the first and second characteristic temperature point values; J is the distance matrix of known data points; r is the distance matrix formed by the data points to be measured and the known data points; ω is the weight vector; S is the temperature value matrix of the known data points; s 1 ~s k is the temperature of the known data point.

[0054] (2) The third and fourth types of characteristic temperature points are adopted as follows:

[0055] T i(x i ,y i )=a 1 (y i 3 -3x i 2 y i )+a 2 (x i 2 +y i 2 )+a 3 (y i 2 -x i 2 )+a 4 x i y i +a 5 x i +a 6 y i +a 7

[0056] Among them: a 1 ~a 7 is the coefficient of the equation; x i Represents the horizontal coordinate of the known data point, y i Indicates the ordinate of a known data point; Y i (x i ,y i ) represents the temperature value of a known data point.

[0057] Substitute the horizontal and vertical coordinates (x i ,y i ), we can get 7 equations, which can be expressed as follows:

[0058]

[0059] In order to calculate the coefficients of the unknowns, the coefficient matrix is ​​inverted and the above formula is transformed into:

[0060]

[0061] Substitute the horizontal and vertical coordinates of the point to be measured to obtain the temperature value of the point to be measured

[0062] T(x,y)=a 1 (y 3 -3x 2 y)+a 2 (x 2 +y 2 )+a 3 (y 2 -x 2 )+a 4xy+a 5 x+a 6 y+a 7

[0063] Where: x, y represent the horizontal and vertical coordinates of the point to be measured; T(x, y) represents the temperature value of the data point to be measured.

[0064] Step 6: Temperature field reconstruction. For any specified position, the type of characteristic temperature point is determined by its location, and the position coordinates are substituted into the corresponding reconstruction function to obtain the temperature distribution monitoring value of the position, thus realizing the online temperature distribution monitoring of the heat pipe reactor core.

[0065] The present invention aims at the characteristics of the solid core of the heat pipe reactor and proposes a technology for online monitoring of the three-dimensional temperature distribution of the reactor based on the measurement signal at a specific position. The present invention can meet the needs of core temperature monitoring of the heat pipe reactor, and the local temperature measurement value can be obtained by using the thermocouples arranged in the fuel assembly, and the average power of the fuel assembly and the average temperature of the matrix can be calculated online in combination with the nuclear design program. The temperature distribution of the core can be obtained by using the data reconstruction technology, which can be used to monitor the state change of the core and implement safety protection.

Claims

1. A method for monitoring core temperature distribution of a solid-state heat pipe reactor, characterized in that: include: The arrangement scheme of fuel rods, heat pipes and thermocouples in the core and the reconstruction technology used for online monitoring of temperature changes using thermocouple temperature changes are specifically as follows: the core of the solid-state heat pipe reactor is arranged with a hexagonal fuel assembly, and the fuel rods and heat pipes in the hexagonal fuel assembly are arranged in a hexagonal array. In order to achieve the purpose of temperature monitoring of the entire assembly, a measurement channel equipped with a thermocouple is arranged at the center of the triangular area formed by every three heat pipes to obtain the local temperature measurement value of the matrix around the measurement channel; in order to monitor the core temperature changes in real time, the nuclear design program calculates the average power of the hexagonal fuel assembly and the average temperature of the matrix around the measurement channel online, and the temperature distribution of the core is obtained by combining the reconstruction technology based on the local temperature measurement data.

2. A method for monitoring core temperature distribution of a solid-state heat pipe reactor according to claim 1, characterized in that: Fuel rods, measuring channels and heat pipes are classified according to their relative positional relationships, and corresponding data reconstruction algorithms are used to reconstruct the three-dimensional temperature field of areas corresponding to different relative positional relationships.

3. A method for monitoring core temperature distribution of a solid-state heat pipe reactor according to claim 2, characterized in that: Classification is carried out according to the relative position relationship of the fuel rod, the measuring channel and the heat pipe. Specifically, classification is carried out according to the arrangement of the components and the position characteristics of the points to be measured. There are four categories in total, namely: the first characteristic temperature point is the temperature of the substrate between the measuring channel and the fuel rod; the second characteristic temperature point is the temperature of the substrate between two fuel rods; the third characteristic temperature point is the temperature of the substrate between the fuel rod and the heat pipe; the fourth characteristic temperature point is the temperature of the substrate between the measuring channel and the heat pipe; different data reconstruction methods are used for characteristic temperature points at different positions; (1) The first and second characteristic temperature points are adopted as follows: Calculate the distance between any two known data points: Where: x i , x j Represents the horizontal coordinate of the known data point, y i ,y j Represents the ordinate of a known data point, d ij Represents the distance between any two data points; The distance matrix is ​​formed and the matrix is ​​transformed as follows: Get a new matrix J: Calculate the value of the measured data point and the obtained weight vector ω to obtain the first and second characteristic temperature point values T(x,y)=rω=r·J -1 S=r·J -1 ·[s1,s2,s3,…,s k ] T Where: x, y represent the horizontal and vertical coordinates of the data points to be measured; T(x, y) represents the first and second characteristic temperature point values; J is the distance matrix of known data points; r is the distance matrix formed by the data points to be measured and the known data points; ω is the weight vector; S is the temperature value matrix of the known data points; s1~s k is the temperature of the known data point; (2) The third and fourth types of characteristic temperature points are adopted as follows: T i (x i ,and i )=a1(and i 3 -3x i 2 and i )+a2(x i 2 +y i 2 )+a3(and i 2 -x i 2 )+a4x i and i +a5x i +a6y i +a7 Among them: a1~a7 are equation coefficients; x i Represents the horizontal coordinate of the known data point, y i Represents the ordinate of a known data point; T i (x i ,y i ) represents the temperature value of a known data point; Substitute the horizontal and vertical coordinates (x i ,y i ), that is, we get 7 equations, which can be expressed as follows: In order to calculate the coefficients of the unknowns, the coefficient matrix is ​​inverted and the above formula is transformed into: Substitute the horizontal and vertical coordinates of the point to be measured to obtain the temperature value of the point to be measured T(x,y)=a1(y 3 -3x 2 y)+a2(x 2 +y 2 )+a3(y 2 -x 2 )+a4xy+a5x+a6y+a7 Where: x, y represent the horizontal and vertical coordinates of the data point to be measured; T(x, y) represents the temperature value of the data point to be measured.

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