A segmented rod position detector for reactor shutdown rods in a nuclear power plant

Abstract

This invention belongs to the field of nuclear power plants, specifically relating to a segmented rod position detector for a shut-down rod group in a nuclear power plant. It includes: an excitation coil, a measuring coil, a measuring coil support slot, and a coil holder. The excitation coil is wound on the coil holder, and the measuring coil support slot is installed on the coil holder, with the measuring coil wound within the slot. The entire rod position measurement range of the shut-down rod group detector is divided into three segments: the first segment is located at the bottom of the coil holder, the second segment is located in the middle of the coil holder, and the third segment is located at the top of the coil holder. The first segment covers five control rod positions, and the third segment covers the maximum operating position of the control rod. This invention effectively simplifies the detector structure and reduces costs while meeting measurement requirements.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plants, specifically relating to a segmented rod position detector for a nuclear power plant shutdown rod group. Background Technology

[0002] The rod bundle control assembly (RCCA) is located in a high-temperature, high-pressure environment in the primary loop, and its position is generally measured using the principle of electromagnetic induction. When the control rod is in different positions within the detector, the inductive reactance of the rod position detector changes, and the excitation current of the measuring coil changes accordingly, thereby obtaining the position of the control rod.

[0003] Currently, most nuclear power technologies use coil-type probe detectors, where the measuring coils are distributed at certain intervals along the entire probe travel sleeve according to the required measurement accuracy.

[0004] Nuclear power plant core control rod groups are divided into shutdown rod groups, temperature rod groups, and power rod groups. During normal operation, the shutdown rod group remains at the top of the core. During shutdown, the shutdown rod group remains at the bottom of the core or the 5-step position. Considering the operating characteristics of the shutdown rod group, its position only needs to be monitored during startup and normal operation. That is, when the control rods are at the bottom and top of the core, the rod position detectors need to meet the measurement accuracy requirements. When the control rods are operating in the middle section, the rod position detectors can be set to low-precision rod position detectors or no rod position detectors can be installed. Summary of the Invention

[0005] The purpose of this invention is to provide a segmented rod position detector for the shutdown rod group of a nuclear power plant. The rod position detector for the shutdown rod group is segmented, and each segment is equipped with rod position measurement coils of different precision. While meeting the measurement requirements, the detector structure is simplified and the cost is reduced.

[0006] Technical solution to achieve the purpose of this invention:

[0007] A segmented rod position detector for a nuclear power plant shutdown rod group includes: an excitation coil, a measuring coil, a measuring coil support slot, and a coil holder; the excitation coil is wound on the coil holder, the measuring coil support slot is installed on the coil holder, and the measuring coil is wound inside the measuring coil support slot; the entire rod position measurement range of the shutdown rod group detector is divided into three segments: the first measurement segment is located at the bottom of the coil holder, the second measurement segment is located in the middle of the coil holder, and the third measurement segment is located at the top of the coil holder; wherein, the first measurement segment covers 5 steps of the control rod position, and the third measurement segment covers the maximum operating position of the control rod.

[0008] The rod position detector includes multiple sets of vertical measuring coils, with each set of vertical measuring coils spaced apart and each set of vertical measuring coils installed in a measuring coil support groove.

[0009] The winding interval between each set of measuring coils in the first and third measurement intervals is set to N steps, so that the rod position detector can achieve the maximum resolution and rod position measurement accuracy requirements.

[0010] The winding interval between each group of measuring coils in the second measurement interval is set to a low-precision bar position measuring coil with more than N steps.

[0011] No measuring coil is wound on the second measurement section.

[0012] The detector further includes: an inner support for the cage, a cage outer shell, a top cover for the rod position detector, and a detector base. The coil cage is a cylindrical body with end plates. The cylindrical body is made of a non-magnetic material, and the outer diameter of the end plates is larger than the outer diameter of the cylindrical body. The coil cage is fitted outside the inner support for the cage, and the cage outer shell is fitted outside the coil cage. The upper part of the cage outer shell is fixedly connected to the top cover for the rod position detector, and the lower part of the cage outer shell is fixedly connected to the detector base.

[0013] The detector also includes a terminal block, through which the external wiring of the measuring coil is achieved.

[0014] The detector also includes: a compression spring and a locking clamp. A compression spring is provided between the top end plate of the coil holder and the lower end face of the detector top cover, and a locking clamp is installed on the detector top cover.

[0015] The beneficial technical effects of this invention are as follows:

[0016] The present invention provides a segmented rod position detector for a shut-down rod group in a nuclear power plant. Based on the operating characteristics of the shut-down rod group, the detector measurement range is divided into three segments. The top and bottom segments of the detector are equipped with measurement coils that meet the measurement accuracy requirements, while the middle segment is equipped with low-precision or no measurement coil. While meeting the actual measurement needs on site, this invention greatly reduces the number of measurement coils, effectively simplifies the internal structure and complexity of the detector, and reduces the cost of the detector. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a segmented rod position detector structure for a nuclear power plant shutdown rod group provided by the present invention;

[0018] Figure 2 This is a schematic diagram of the distribution of rod position measurement intervals in a segmented rod position detector for a nuclear power plant shutdown rod group provided by the present invention;

[0019] Figure 3 This invention provides a schematic diagram of the distribution of measuring coils in each measuring section of a segmented rod position detector for a nuclear power plant shutdown rod group: Figure 3 (a) A low-precision rod position measurement coil is wound on the second measurement section. Figure 3(b) No measuring coil is wound in the second measurement section.

[0020] In the diagram: 1-excitation coil, 2-measuring coil, 3-measuring coil support slot, 4-coil retainer, 5-inner support of retainer, 6-retainer housing, 7-terminal block, 8-locking clamp, 9-detector top cover, 10-compression spring, 11-detector base. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, the present invention provides a segmented rod position detector for a nuclear power plant shutdown rod group, comprising: an excitation coil 1, a measuring coil 2, a measuring coil support groove 3, a coil retainer 4, an inner support within the retainer 5, a retainer housing 6, a terminal block 7, a locking clamp 8, a rod position detector top cover 9, a compression spring 10, and a detector base 11.

[0023] The rod position detector's measuring coil consists of an excitation coil 1 and a discrete measuring coil 2. The coil holder 4 is a thin-walled cylinder with end plates, made of non-magnetic material, with the outer diameter of the end plates larger than the outer diameter of the cylinder. The excitation coil 1 is wound on the coil holder 4, and a measuring coil support slot 3 is installed on the coil holder 4. The measuring coil 2 is wound inside the measuring coil support slot 3. Both the inner support 5 and the outer shell 6 of the holder are thin-walled structures. The coil holder 4 is fitted over the inner support 5, and the outer shell 6 is fitted over the coil holder 4. The upper part of the outer shell 6 is connected to the rod position detector's top cover 9 by screws, and the lower part is connected to the detector base 11 by screws and welding. The inner support 5 and the outer shell 6 provide support and protection for the excitation coil 1 and the measuring coil 2. External wiring of the measuring coil 2 is achieved through a terminal block 7. A compression spring 10 is provided between the top end plate of the coil holder 4 and the lower end face of the detector's top cover 9, and a locking clamp 8 is installed on the detector's top cover 9.

[0024] The excitation coil 1 is wound and distributed on the coil holder 4. The excitation coil 1 receives AC power as its electromagnetic excitation power. When the control rod drops, the power supply to the excitation coil 1 is cut off, and an induced voltage is generated on both sides of it for measuring the drop time.

[0025] The rod position detector includes multiple sets of vertical measuring coils 2, each set of vertical measuring coils 2 is spaced a certain distance apart, and each set of vertical measuring coils 2 is installed in a measuring coil support groove 3. When the control rod is within its measuring range, the induced voltage amplitude of the measuring coil 2 is larger, and vice versa.

[0026] When the control rod moves within the measurement range of the rod position detector, the difference between the induced voltage of the measurement coil covered by the control rod's operating position and the induced voltage of the measurement coil not covered can be identified.

[0027] like Figure 2 As shown, the rod position detector for the stop rod assembly is divided into three sections: the first section is located at the bottom of the coil holder 4, the second section is located in the middle of the coil holder 4, and the third section is located at the top of the coil holder 4. The first section covers five control rod positions, and the third section covers the maximum operating position of the control rod.

[0028] The winding interval between each group of measuring coils 2 in the first and third measurement intervals is set to N steps. The arrangement of measuring coils 2 is shown in the diagram below. Figure 3 As shown, this mainly depends on the maximum resolution that the rod position detector can achieve and the accuracy requirements of the rod position measurement.

[0029] The winding interval between each group of measuring coils 2 in the second measurement interval is set to a low-precision bar position measuring coil with a step interval greater than N. The arrangement of measuring coils 2 is shown in the figure. Figure 3 As shown in (a); or the measuring coil 2 is not wound around the rod position in the second measurement interval, and the arrangement of the measuring coil 2 is shown in the diagram. Figure 3 As shown in (b).

[0030] In the research project on key technologies for optimization and improvement of third-generation pressurized water reactors, the rod position detector proposed in this invention has been tested and verified. The test results show that the rod position detector proposed in this invention meets the rod position measurement requirements of the shut-down rod group, simplifies the number of detector coils, reduces the detector cost, and has great application value.

[0031] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. All contents not described in detail in the present invention can be derived from existing technologies.

Claims

1. A segmented rod position detector for a nuclear power plant shutdown rod group, characterized in that, The detector includes: an excitation coil (1), a measuring coil (2), a measuring coil support slot (3), and a coil holder (4); the excitation coil (1) is wound on the coil holder (4), the measuring coil support slot (3) is installed on the coil holder (4), and the measuring coil (2) is wound inside the measuring coil support slot (3); the entire rod position measurement range of the stop rod group detector is divided into three sections, the first measurement range is located at the bottom of the coil holder (4), the second measurement range is located in the middle of the coil holder (4), and the third measurement range is located at the top of the coil holder (4); the first measurement range covers 5 steps of the control rod position, and the third measurement range covers the maximum operating position of the control rod.

2. The segmented rod position detector for a nuclear power plant shutdown rod group according to claim 1, characterized in that, The rod position detector includes multiple sets of vertical measuring coils (2), each set of vertical measuring coils (2) is spaced apart, and each set of vertical measuring coils (2) is installed in a measuring coil support groove (3).

3. A segmented rod position detector for a nuclear power plant shutdown rod group according to claim 2, characterized in that, The winding interval between each set of measuring coils (2) in the first and third measurement intervals is set to N steps, so that the rod position detector can achieve the maximum resolution and rod position measurement accuracy requirements.

4. A segmented rod position detector for a nuclear power plant shutdown rod group according to claim 2, characterized in that, The winding interval between each group of measuring coils (2) in the second measurement interval is set to a low-precision bar position measuring coil with more than N steps.

5. A segmented rod position detector for a nuclear power plant shutdown rod group according to claim 2, characterized in that, No measuring coil (2) is wound on the second measurement section.

6. A segmented rod position detector for a nuclear power plant shutdown rod group according to claim 1, characterized in that, The detector also includes: an inner support (5), a cage shell (6), a rod position detector top cover (9), and a detector base (11). The coil cage (4) is a cylinder with end plates. The cylinder material is a non-magnetic material, and the outer diameter of the end plates is larger than the outer diameter of the cylinder. The coil cage (4) is fitted outside the inner support (5), and the cage shell (6) is fitted outside the coil cage (4). The upper part of the cage shell (6) is fixedly connected to the rod position detector top cover (9), and the lower part of the cage shell (6) is fixedly connected to the detector base (11).

7. A segmented rod position detector for a nuclear power plant shutdown rod group according to claim 1, characterized in that, The detector also includes a terminal block (7), through which the external wiring of the measuring coil (2) is achieved.

8. A segmented rod position detector for a nuclear power plant shutdown rod group according to claim 6, characterized in that, The detector also includes: a compression spring (10) and a locking clamp (8). A compression spring (10) is provided between the top end plate of the coil holder (4) and the lower end face of the detector top cover (9). A locking clamp (8) is installed on the detector top cover (9).

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