Sectional rod position detector for shutdown rod group of nuclear power station

Abstract

The invention belongs to the field of nuclear power stations, and particularly relates to a nuclear power station shutdown rod group sectional rod position detector which comprises a magnet exciting coil, a measuring coil, a measuring coil supporting groove and a coil holder. The magnet exciting coil is wound on the coil holder, a measuring coil supporting groove is formed in the coil holder, and the measuring coil is wound in the measuring coil supporting groove; the whole rod position measurement interval of the shutdown rod group rod position detector is divided into three sections, the first section of measurement interval is located in the bottom interval of the coil holder, the second section of measurement interval is located in the middle interval of the coil holder, and the third section of measurement interval is located in the top interval of the coil holder; wherein the first section of measurement interval covers the five-step position of the control rod, and the third section of measurement interval covers the maximum operation position of the control rod. On the premise of meeting the measurement requirements, the structure of the detector is effectively simplified, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power plants, and in particular relates to a segmented rod position detector for a shutdown rod group of a nuclear power plant. Background Art

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

[0003] At present, the rod position detectors used in most nuclear power technologies are coil-type detectors, that is, the measuring coils are distributed on the entire detector travel casing at a certain interval according to the measurement accuracy requirements.

[0004] The core control rod group of a nuclear power plant is divided into a shutdown rod group, a temperature rod group and a power rod group. During normal operation, the shutdown rod group is always kept at the top of the core. During shutdown, the shutdown rod group is kept at the bottom of the core or the 5-step position. In view of the operating characteristics of the shutdown rod group, it is only necessary to monitor its rod position during startup and normal operation. That is, when the control rod is at the bottom and top of the core, the setting of the rod position detector needs to meet the measurement accuracy requirements. When the control rod is running in the middle section, the rod position detector can be set to a low-precision rod position detector or no rod position detector is set. Summary of the invention

[0005] The object of the present invention is to provide a nuclear power plant shutdown rod group segmented rod position detector, the shutdown rod group rod position detector is divided into segments, each segment is provided with a rod position measurement coil of different precision, under the premise of meeting the measurement requirements, the detector structure is simplified and the cost is reduced.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A nuclear power plant shutdown rod group segmented rod position detector, the detector comprising: an excitation coil, a measuring coil, a measuring coil supporting groove, and a coil holder; the excitation coil is wound on the coil holder, the coil holder is provided with a measuring coil supporting groove, and the measuring coil is wound in the measuring coil supporting groove; the entire rod position measurement interval of the shutdown rod group rod position detector is divided into three sections, the first measurement interval is located at the bottom interval of the coil holder, the second measurement interval is located at the middle interval of the coil holder, and the third measurement interval is located at the top interval of the coil holder; wherein the first measurement interval covers 5-step positions of the control rod, and the third measurement interval covers the maximum operating position of the control rod.

[0008] The rod position detector comprises a plurality of groups of vertical measuring coils, each group of vertical measuring coils is arranged at intervals, and each group of vertical measuring coils is installed in a measuring coil supporting groove.

[0009] The winding interval between each group of measuring coils in the first measuring interval and the third measuring interval 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 measuring interval is set to be a low-precision rod position measuring coil greater than N steps.

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

[0012] The detector also includes: an inner support of a holder, an outer shell of a holder, a rod-position detector top cover, and a detector base. The coil holder is a cylinder with an end plate, the cylinder material is a non-magnetic material, and the outer diameter of the end plate is larger than the outer diameter of the cylinder; the coil holder is sleeved on the outside of the inner support of the holder, and the outer shell of the holder is sleeved on the outside of the coil holder; the upper part of the outer shell of the holder is fixedly connected to the top cover of the rod-position detector, and the lower part of the outer shell of the holder is fixedly connected to the detector base.

[0013] The detector further comprises: a terminal block, and external wiring of the measuring coil is realized through the terminal block.

[0014] The detector further comprises: a compression spring and a locking hoop. A compression spring is arranged between the top end plate of the coil holder and the lower end surface of the detector top cover, and a locking hoop is installed on the detector top cover.

[0015] The beneficial technical effects of the present invention are:

[0016] The present invention provides a segmented rod position detector for a nuclear power plant shutdown rod group. The detector side measurement range is divided into three sections according to the operating characteristics of the shutdown rod group. The segments located at the top and bottom of the detector are equipped with measuring coils that meet the measurement accuracy requirements, and the middle section is equipped with low-precision or no measuring coils. While meeting the actual measurement needs on site, the number of measuring coils is greatly reduced, the internal structure and complexity of the detector are effectively simplified, and the detector cost is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0018] Figure 2 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 A schematic diagram of the distribution of measuring coils in each measuring interval of a segmented rod position detector for a nuclear power plant shutdown rod group provided by the present invention: Figure 3 (a) is a low-precision rod position measurement coil wound on the second measurement interval. Figure 3(b) The second measurement section has no measuring coil wound around it.

[0020] In the figure: 1-excitation coil, 2-measuring coil, 3-measuring coil support groove, 4-coil holder, 5-holder inner support, 6-holder housing, 7-terminal row, 8-locking hoop, 9-detector top cover, 10-compression spring, 11-detector base. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

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

[0023] The rod position detector measuring coil is composed of an excitation coil 1 and a discrete measuring coil 2. The coil holder 4 is a thin-walled cylinder with an end plate, the cylinder material is a non-magnetic material, and the outer diameter of the end plate is larger than the outer diameter of the cylinder; the excitation coil 1 is wound on the coil holder 4, and the coil holder 4 is equipped with a measuring coil support groove 3, and the measuring coil 2 is wound in the measuring coil support groove 3; the inner support 5 of the holder and the outer shell 6 of the holder are both thin-walled structures, the coil holder 4 is sleeved outside the inner support 5 of the holder, and the outer shell 6 of the holder is sleeved outside the coil holder 4; the upper part of the outer shell 6 of the holder is connected to the top cover 9 of the rod position detector by screws, and the lower part of the outer shell 6 of the holder is connected to the base 11 of the detector by screws and welding. The inner support 5 of the holder and the outer shell 6 of the holder provide support and protection for the excitation coil 1 and the measuring coil 2; the external wiring of the measuring coil 2 is realized through the terminal block 7. A compression spring 10 is provided between the top end plate of the coil holder 4 and the lower end surface of the detector top cover 9, and a locking hoop 8 is installed on the detector top cover 9.

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

[0025] The rod position detector includes multiple groups of vertical measuring coils 2, each group of vertical measuring coils 2 is spaced a certain distance apart, and each group of vertical measuring coils 2 is installed in a measuring coil support slot 3. When the control rod is within its measuring range, the induced voltage amplitude of the measuring coil 2 is larger, otherwise it is smaller.

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

[0027] like Figure 2 As shown, the entire rod position measurement interval of the shutdown rod group rod position detector is divided into three sections, the first measurement interval is located at the bottom section of the coil holder 4, the second measurement interval is located in the middle section of the coil holder 4, and the third measurement interval is located at the top section of the coil holder 4. Among them, the first measurement interval covers the 5-step position of the control rod, and the third measurement interval covers the maximum operating position of the control rod.

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

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

[0030] In the key technology research project for optimizing and improving the third-generation pressurized water reactor, the rod position detector proposed in the present invention has been tested and verified. The test results show that the rod position detector proposed in the present invention meets the rod position measurement requirements of the shutdown rod group, simplifies the number of detector coils, reduces the cost of the detector, and has great application value.

[0031] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A segmented rod position detector for a nuclear power plant shutdown rod group, characterized in that: The detector comprises: an excitation coil (1), a measuring coil (2), a measuring coil support groove (3), and a coil holder (4); the excitation coil (1) is wound on the coil holder (4), the coil holder (4) is provided with a measuring coil support groove (3), and the measuring coil (2) is wound in the measuring coil support groove (3); the entire rod position measurement interval of the shutdown rod group rod position detector is divided into three sections, the first measurement interval is located at the bottom section of the coil holder (4), the second measurement interval is located at the middle section of the coil holder (4), and the third measurement interval is located at the top section of the coil holder (4); wherein the first measurement interval covers the 5-step position of the control rod, and the third measurement interval covers the maximum operating position of the control rod.

2. A nuclear power plant shutdown rod group segmented rod position detector according to claim 1, characterized in that: The rod position detector comprises a plurality of groups of vertical measuring coils (2), each group of vertical measuring coils (2) being arranged at intervals, and each group of vertical measuring coils (2) being installed in a measuring coil supporting groove (3).

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

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

5. A nuclear power plant shutdown rod group segmented rod position detector according to claim 2, characterized in that: The second measuring section has no measuring coil (2) wound around it.

6. A nuclear power plant shutdown rod group segmented rod position detector according to claim 1, characterized in that: The detector further comprises: a retaining frame inner support (5), a retaining frame outer shell (6), a rod position detector top cover (9), and a detector base (11); the coil retaining frame (4) is a cylinder with an end plate, the cylinder body material is a non-magnetic material, and the outer diameter of the end plate is larger than the outer diameter of the cylinder; the coil retaining frame (4) is sleeved on the outside of the retaining frame inner support (5), and the retaining frame outer shell (6) is sleeved on the outside of the coil retaining frame (4); the upper part of the retaining frame outer shell (6) is fixedly connected to the rod position detector top cover (9), and the lower part of the retaining frame outer shell (6) is fixedly connected to the detector base (11).

7. A nuclear power plant shutdown rod group segmented rod position detector according to claim 1, characterized in that: The detector further comprises a terminal block (7), and external wiring of the measuring coil (2) is realized via the terminal block (7).

8. A nuclear power plant shutdown rod group segmented rod position detector according to claim 6, characterized in that: The detector further comprises: a compression spring (10) and a locking hoop (8); a compression spring (10) is arranged between the top end plate of the coil holder (4) and the lower end surface of the detector top cover (9); and a locking hoop (8) is installed on the detector top cover (9).

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