Self-powered detector on-pile test device and method

Abstract

The invention relates to a self-powered detector on-pile test device and method.The device comprises an outer support fixed in a test dry hole channel and an inner support coaxially nested in an inner cavity of the outer support, the outer diameter of the outer support and the inner diameter of the test dry hole channel form micro-tight fit, and the inner support can rotate around the axis relative to the outer support; a first mounting position for mounting at least one standard self-powered detector is arranged on the outer support, a second mounting position for mounting at least one self-powered detector to be detected is arranged on the inner support, and a cross arm is arranged at the bottom of the outer support and used for being in contact with the lower end of the inner support so as to limit the axial insertion position of the inner support. According to the on-pile test device and method for the self-powered detector, single-point calibration errors caused by uneven radial distribution of neutron fluence rates can be effectively eliminated or greatly reduced, and the calibration precision and the representativeness of results are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactor detector technology, and in particular to a self-powered on-reactor detector test apparatus and method. Background Technology

[0002] Self-powered neutron detectors are widely used in measuring the thermal neutron flux rate inside reactor cores due to their advantages such as high thermal neutron sensitivity, moderate response time, and small size. Their output current is proportional to the neutron flux rate. Therefore, accurately calibrating their sensitivity is the key to ensuring the accuracy of core power distribution monitoring.

[0003] On-reactor testing is an important method for calibrating the sensitivity of self-powered detectors. It is typically conducted in a vertical test channel (dry or wet) within the reactor. The conventional method involves placing the detector under test (DUT) and a standard detector with known sensitivity within the same test channel, and then comparing their output currents to estimate the DUT's sensitivity. However, due to the influence of fuel assemblies, control rods, and other structures within the reactor core, the neutron flux rate exhibits a significant non-uniform spatial distribution at different radial azimuth angles within the same test channel. If the DUT is fixed at a single azimuth angle for single-point measurement, the obtained sensitivity value only represents the local response characteristics and cannot accurately reflect the detector's response to the average neutron field across the entire radial interface. This introduces systematic errors caused by the measurement location selection, reducing the representativeness and reliability of the calibration results. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a self-powered detector on-pile testing apparatus and method to solve the above problems.

[0005] For the purposes described above, the present invention provides:

[0006] A self-sufficient energy detector on-pile test apparatus, comprising:

[0007] An outer support is used to fix it inside the test dry channel, and the outer diameter of the outer support and the inner diameter of the test dry channel form a tight fit.

[0008] The inner support can be coaxially inserted into the inner cavity of the outer support and can rotate about an axis relative to the outer support;

[0009] The outer bracket is provided with a first mounting position for installing at least one standard self-powered detector, and the inner bracket is provided with a second mounting position for installing at least one self-powered detector to be tested.

[0010] The bottom of the outer support is provided with a crossbeam for contacting the lower end of the inner support to limit the axial insertion position of the inner support.

[0011] Preferably, the outer support includes a plurality of annular support units spaced apart along the axial direction, the standard self-powered detector is inserted into and fixed in the plurality of annular support units, forming the main support structure of the outer support, and the crossbeam is welded to the lowest annular support unit.

[0012] Preferably, the annular support unit has a mounting hole for the standard self-powered detector to pass through. The port of the mounting hole extends to form two symmetrical and elastic clamping rings. The two clamping rings clamp the standard self-powered detector passing through the mounting hole, so as to realize the quick assembly and disassembly of the standard self-powered detector and the annular support unit and fix its position.

[0013] Preferably, the lower end of the inner support is provided with a spherical contact, and the upper surface of the crossarm is provided with a conical positioning groove adapted to the spherical contact. When the inner support is inserted into the inner cavity of the outer support, the spherical contact abuts against the bottom of the conical positioning groove, thereby realizing the radial automatic centering and axial positioning of the inner support and allowing the inner support to rotate freely around the spherical contact.

[0014] Preferably, the top of the outer support is provided with a support ring, which is fixedly connected to the uppermost structure of the outer support through several connecting rods. The outer diameter of the support ring is larger than the inner diameter of the test channel port, and is used to abut against the test channel port to prevent the entire outer support from falling into the test channel.

[0015] Preferably, the inner support extends upward to form a cylindrical guide rod, and a limit ring is provided on the guide rod. A quick-operation limiting structure is installed on the support ring. After the inner support is inserted into the inner cavity of the outer support, the limiting structure is operated to act above the limit ring to limit the upward axial displacement of the inner support relative to the outer support. The guide rod extends upward through the limiting structure, and its top end is used to connect the inner support hoisting line.

[0016] Preferably, the limiting structure includes a base fixedly mounted on the support ring. The base has a sliding hole extending radially along the support ring. A cylindrical locking tongue passes through the sliding hole. The base has a spring acting on the locking tongue, causing the locking tongue to slide towards the center of the support ring. A limiting protrusion is formed on the side of the locking tongue away from the center of the support ring. A limiting groove adapted to the limiting protrusion is formed on the inner wall of the sliding hole. When the limiting protrusion is inserted into the limiting groove, the end of the locking tongue is located above the limiting ring, thus limiting the upward axial displacement of the inner bracket within the outer bracket.

[0017] Preferably, the guide rod has an axially through wiring cavity inside, and a through hole communicating with the wiring cavity is opened on its side wall. The signal cable of the self-powered detector under test, which is installed on the inner bracket, is introduced into the wiring cavity through the through hole and led out from the top of the guide rod.

[0018] Preferably, a first thermocouple and a second thermocouple are respectively installed on the outer support and the inner support, and the first thermocouple and the second thermocouple are used to monitor the temperature of the microenvironment in which the standard self-powered detector and the self-powered detector under test are located.

[0019] A method for on-pile calibration of a self-powered detector based on the above-mentioned device includes the following steps:

[0020] S1. Place the outer bracket with the standard self-powered detector into the test dry channel and fix it. Place the inner bracket with the self-powered detector to be tested into the inner cavity of the outer bracket until the lower end of the inner bracket contacts and positions itself against the crossbeam.

[0021] S2. After the reactor power stabilizes, drive the inner support to rotate at a constant speed relative to the outer support in the radial plane for at least one revolution through the inner support hoisting line. During the rotation, pause at multiple equiangular intervals. After the signal stabilizes, synchronously record the output current of each standard self-powered detector and the self-powered detector under test.

[0022] S3. Calculate the arithmetic mean of the output current of each self-powered detector under test at all recorded positions within one rotation, and use it as its average response current. Based on the output current of the standard self-powered detector and its known sensitivity, calculate and deduce the theoretical average neutron fluence rate of the test dry channel in the radial plane where the inner support is located.

[0023] S4. Divide the average response current of each self-powered detector under test by the corresponding theoretical average neutron fluence rate to obtain the calibration sensitivity of each self-powered detector under test.

[0024] The beneficial effects of this invention are:

[0025] 1. By establishing a spatial reference through a fixed standard self-powered detector, the average neutron field is calculated. By rotating the self-powered detector under test one revolution, the circumferential average response current is obtained. The radial non-uniform neutron field of the reactor is actively integrated in space, which effectively eliminates or significantly reduces the single-point calibration error caused by the uneven radial distribution of neutron flux rate, and significantly improves the calibration accuracy and representativeness of the results.

[0026] 2. The outer support adopts a lightweight cage structure composed of a ring support unit and a standard self-powered detector, which reduces the metal footprint and helps to reduce the disturbance to the neutron field inside the reactor. The inner support achieves radial self-centering and axial positioning with the outer support through the cooperation of spherical contacts and conical positioning grooves. This ensures the positional accuracy of the inner and outer supports after nesting installation, and also ensures low-resistance, interference-free free rotation between the inner and outer supports, which facilitates the implementation of calibration tests.

[0027] 3. The standard self-contained energy detector is assembled with the ring-shaped support unit through a clamping ring, which facilitates the assembly and disassembly of the standard self-contained energy detector and the adjustment of the position of the ring-shaped support unit on the standard self-contained energy detector. The overall length of the outer support can be adjusted to match the test dry channel or the self-contained energy detector under test. The limiting structure at the top of the outer support limits the inner support through quick operation, which improves the efficiency and safety of the calibration test. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the present invention installed in the test dry channel;

[0030] Figure 2 This is a schematic diagram of the structure of the present invention;

[0031] Figure 3 This is a cross-sectional schematic diagram of the present invention;

[0032] Figure 4 for Figure 3 Enlarged view of point A in the middle;

[0033] Figure 5 for Figure 3 Enlarged view of point B in the middle;

[0034] Figure 6 This is a schematic diagram of the structure of the external support in this invention;

[0035] Figure 7 This is a schematic diagram of the internal support structure in this invention;

[0036] Figure 8 This is a cross-sectional schematic diagram of the limiting structure in this invention.

[0037] The diagram is marked as follows:

[0038] 1. Test dry channel; 2. Outer support; 21. Annular support unit; 211. Mounting hole; 212. Clamping ring; 22. Crossbeam; 221. Conical positioning groove; 23. Support ring; 24. Connecting rod; 3. Inner support; 31. Spherical contact; 32. Axial groove; 33. Guide rod; 331. Wiring cavity; 332. Wire hole; 34. Limiting ring; 35. Limiting structure; 351. Base; 352. Sliding hole; 353. Locking tongue; 354. Spring; 355. Limiting protrusion; 356. Limiting groove; 4. Standard self-powered detector; 5. Self-powered detector under test; 6. First thermocouple; 7. Second thermocouple. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0040] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0041] like Figure 1-8 As shown, this embodiment provides a self-powered detector on-pile test apparatus, which constructs a support system in which a fixed reference unit and a rotatable scanning unit are nested together to perform a self-powered detector calibration test method aimed at eliminating the influence of radial neutron distribution non-uniformity.

[0042] The device includes an outer support 2 and an inner support 3. The outer support 2 is used as a fixed spatial reference unit to be inserted and fixed as a whole in the test dry channel 1. The outer diameter of the outer support 2 is slightly smaller than the inner diameter of the test dry channel 1. After the outer support 2 is inserted into the test dry channel 1, it is slightly tight-fitted with the inner wall of the test dry channel 1. The inner support 3 is a movable measurement and scanning unit that can be coaxially inserted into the inner cavity of the outer support 2. The inner support 3 can be driven by the inner support 3 hoisting line at the top to rotate relative to the outer support 2 around a common axis.

[0043] The specific structure of the outer support 2 is as follows: Figure 3-6As shown, the structure consists of multiple axially equidistant annular support units 21 connected to multiple standard self-powered detectors 4 that pass through and are fixedly connected to the annular support units 21. The standard self-powered detectors 4 themselves serve as structural components, forming a stable, lightweight cage frame with minimal metal footprint together with the annular support units 21. This helps reduce disturbance to the neutron field within the reactor. To facilitate the assembly and disassembly of the standard self-powered detectors 4 and the annular support units 21, several mounting holes 211 are provided on the annular support units 21. The ports of the mounting holes 211 extend to form two symmetrical and elastic clamping rings 212. During installation, the standard self-powered detectors 4 are passed through the mounting holes 211 and pressed between the two clamping rings 212. The two clamping rings 212 clamp the standard self-powered detectors 4 by the clamping force generated by their elastic deformation, thus facilitating the quick assembly and disassembly of individual standard detectors and fine position adjustments.

[0044] A crossbeam 22 is welded to the lowest annular support unit 21. A conical positioning groove 221 is provided at the center of the upper surface of the crossbeam 22. A support ring 23 is fixedly connected to the top of the highest annular support unit 21 by several connecting rods 24. The outer diameter of the support ring 23 is larger than the inner diameter of the port of the test dry channel 1, and the top of the support ring 23 is used to connect the hoisting line of the outer support 2. When the outer support 2 is placed in the test dry channel 1, the support ring 23 abuts against the port of the test dry channel 1, ensuring the stability of the outer support 2 placed in the test dry channel 1 while preventing the outer support 2 from falling into the test dry channel 1 as a whole.

[0045] The outer support 2 is also equipped with a first thermocouple 6 that passes through the ring support unit 21. The measuring end of the first thermocouple 6 is aligned with the midpoint of the emitter of the standard self-powered detector 4 to monitor the temperature of the microenvironment in which the standard self-powered detector 4 is located, so as to prevent the test environment temperature from being too high and causing danger.

[0046] The specific structure of the internal support 3 is as follows: Figure 2 , 3As shown in Figures 4 and 7, the main body is a rod-shaped or tubular structure. Several axial grooves 32 are formed on its sidewalls for mounting the self-powered detector 5 under test. After the self-powered detector 5 is embedded in the axial grooves 32, it is fixedly mounted on the inner bracket 3 by straps. A hemispherical spherical contact 31 matching the conical positioning groove 221 is welded to the center of the bottom of the inner bracket 3. A cylindrical guide rod 33 extends integrally from or is connected to the top of the inner bracket 3. The guide rod 33 has a hollow interior forming an axially penetrating wiring cavity 331. Several through holes 332 communicating with the wiring cavity 331 are formed on the sidewalls of the guide rod 33. The signal cable of the self-powered detector 5 fixedly mounted on the inner bracket 3 is introduced into the wiring cavity 331 through the through holes 332 and leads out from the top of the guide rod 33. A limit ring 34 is sleeved and fixed on the guide rod 33. The outer diameter of the limit ring 34 matches the inner diameter of the support ring 23. The support ring 23 is provided with a quick-operation limit. Structure 35: After the inner support 3 is inserted into the inner cavity of the outer support 2, the spherical contact 31 automatically slides into the center of the conical positioning groove 221 of the crossarm 22 under the action of gravity and contacts the bottom of the conical positioning groove 221, realizing the radial automatic centering and axial positioning of the inner support 3 and the outer support 2, and allowing the inner support 3 to rotate freely around the spherical contact 31 in the outer support 2 along the common axis of the inner support 3 and the outer support 2. At this time, the limiting ring 34 is located in the support ring 23. The operating limiting structure 35 is made to act above the limiting ring 34 to limit the upward axial position of the inner support 3 relative to the outer support 2, so that the axial position of the inner support 3 relative to the outer support 2 remains stable when the inner support 3 rotates. The guide rod 33 passes upward through the limiting structure 35, and its top end is used to connect the inner support 3 hoisting line. The signal cable of the self-powered detector 5 under test led out from the top of the guide rod 33 is connected to the monitoring equipment, and the signal cable of the standard self-powered detector 4 passes through the support ring 23 and is connected to the monitoring equipment.

[0047] A second thermocouple 7 is also installed on the inner support 3. The second thermocouple 7 is embedded in the axial groove 32 opened on the side of the inner support 3. The measuring end of the second thermocouple 7 is aligned with the center of the emitter of the self-powered detector 5 under test. It is used to monitor the temperature of the microenvironment where the self-powered detector 5 is located and to prevent the test environment temperature from being too high and causing danger.

[0048] The specific structure of the limiting structure 35 is as follows: Figure 8As shown, the device includes a base 351 fixedly mounted on a support ring 23. The base 351 has a sliding hole 352 extending radially along the support ring 23. A cylindrical locking tongue 353 passes through the sliding hole 352. A spring 354 acts on the locking tongue 353, causing it to tend to slide towards the center of the support ring 23. A limiting protrusion 355 is formed on the side of the locking tongue 353 away from the center of the support ring 23. A limiting groove 356, adapted to the limiting protrusion 355, is formed on the inner wall of the sliding hole 352. Before the inner bracket 3 is inserted into the outer bracket 2, the locking tongue 353 is pulled to slide away from the center of the support ring 23, and the limiting protrusion 355 slides with the locking tongue 353. Exit the limiting groove 356 and rotate the locking tongue 353 so that the end of the limiting protrusion 355 abuts against the port of the sliding hole 352. At this time, the end of the locking tongue 353 leaves from above the inner hole of the support ring 23, allowing the inner bracket 3 to be inserted into the inner cavity of the outer bracket 2 through the inner hole of the support ring 23. When the inner bracket 3 is inserted into the outer bracket 2, rotate the locking tongue 353 so that the limiting protrusion 355 is aligned with the limiting groove 356. Under the restoring force of the spring 354, the locking tongue 353 slides towards the center of the support ring 23, so that the end of the locking tongue 353 is located above the limiting ring 34, thereby restricting the upward axial position of the inner bracket 3 in the outer bracket 2 and realizing the rapid operation of the upward axial limitation of the inner bracket 3 in the outer bracket 2.

[0049] A calibration method for a self-powered detector based on the above-mentioned experimental apparatus includes the following steps:

[0050] S1. First, the outer bracket 2, equipped with the standard self-powered detector 4 and the first thermocouple 6, is guided vertically into the selected test dry channel 1 by the lifting line of the outer bracket 2, which is fixedly connected to the top of the support ring 23, until the support ring 23 abuts against the port of the test dry channel 1. Then, the inner bracket 3, equipped with the self-powered detector 5 to be tested and the second thermocouple 7, is guided vertically into the inner cavity of the outer bracket 2 by the lifting line of the inner bracket 3, which is fixedly connected to the top of the guide rod 33, so that the spherical contact 31 at the bottom of the inner bracket 3 is aligned with the inner cavity entrance of the outer bracket 2. The spherical contact 31 automatically slides into the conical positioning groove 221 and contacts the bottom of the conical positioning groove 221. The spherical contact 31 and the conical positioning groove 221 cooperate to achieve axial positioning of the inner bracket 3 in the outer bracket 2. The free rotation of the spherical contact 31 in the positioning groove achieves radial rotation of the inner bracket 3 in the outer bracket 2. Then, the limiting structure 35 is operated to make the locking tongue 353 slide above the limiting ring 34, which restricts the upward axial displacement of the inner bracket 3 in the outer bracket 2 and ensures the stability of the inner bracket 3 when rotating in the outer bracket 2.

[0051] S2. Start the reactor and increase it to the predetermined stable power. Rotate the inner support 3 at a uniform speed through an external mechanism (manual or motor driven) connected to the inner support 3 hoisting line, so that the inner support 3 and the self-powered detector 5 under test mounted on it rotate smoothly inside the outer support 2. The rotation speed of the inner support 3 should be slow enough to ensure that each measurement point has sufficient signal stabilization time. The inner support 3 should pause after rotating a fixed angle (e.g., 30°). After the output current of the self-powered detector 5 under test stabilizes, the current data of the self-powered detector 5 under test and the standard self-powered detector 4, as well as the temperature data of the first thermocouple 6 and the second thermocouple 7, are collected and recorded simultaneously. This process continues until the inner support 3 has rotated a full revolution (i.e., the inner support 3 rotates 360°).

[0052] S3. For each self-powered detector 5 under test, the arithmetic average of the current values ​​recorded at various angular positions during its rotation with the inner support 3 is taken to obtain the circumferential average response current. At the same time, based on the current value measured at its fixed position by the standard self-powered detector 4, combined with the known sensitivity of the standard self-powered detector 4, the real-time neutron fluence at that fixed position is calculated. Based on the prior knowledge of the neutron fluence distribution in the reactor physics model or the experimental dry channel 1, the theoretical average neutron fluence of the entire calibration radial plane is deduced from the neutron fluence at that fixed position.

[0053] S4. Divide the average response current of each self-powered detector 5 under test by the corresponding theoretical average neutron fluence rate to obtain the calibration sensitivity of each self-powered detector 5 under test.

[0054] In the above-mentioned experimental setup and method, a spatial reference is established by fixing the standard self-powered detector 4 to calculate the average neutron field. By rotating the self-powered detector 5 under test one revolution, the circumferential average response current is obtained, and the radial non-uniform neutron field of the reactor is actively integrated spatially. This effectively eliminates or significantly reduces the single-point calibration error caused by the uneven radial distribution of neutron flux, and significantly improves the calibration accuracy and representativeness of the results. The outer support 2 adopts a lightweight cage structure composed of a ring-shaped support unit 21 and the standard self-powered detector 4, which reduces the metal footprint and helps to reduce the disturbance to the neutron field inside the reactor. The inner support 3 uses the cooperation of the spherical contact 31 and the conical positioning groove 221. The inner support 3 and outer support 2 achieve radial self-centering and axial positioning, ensuring the positional accuracy of the inner support 3 after nesting with the outer support 2, and also ensuring low-resistance, interference-free free rotation between the inner support 3 and outer support 2, which facilitates the implementation of calibration tests. The standard self-powered detector 4 is assembled with the annular support unit 21 through the clamping ring 212, which facilitates the disassembly and assembly of the standard self-powered detector 4 and the position adjustment of the annular support unit 21 on the standard self-powered detector 4. The overall length of the outer support 2 is adjusted to match the test dry channel 1 or the self-powered detector 5 to be tested. The limiting structure 35 at the top of the outer support 2 limits the inner support 3 through quick operation, improving the efficiency and safety of calibration tests.

[0055] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0056] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A self-sufficient energy detector on-pile testing device, characterized in that, include: An outer support (2) is used to fix it inside the test dry channel (1). The outer diameter of the outer support (2) and the inner diameter of the test dry channel (1) form a tight fit. The inner support (3) can be coaxially inserted into the inner cavity of the outer support (2) and can rotate about the axis relative to the outer support (2); The outer bracket (2) is provided with a first mounting position for installing at least one standard self-powered detector (4), and the inner bracket (3) is provided with a second mounting position for installing at least one self-powered detector (5) to be tested; The bottom of the outer support (2) is provided with a crossbeam (22) for contacting the lower end of the inner support (3) to limit the axial insertion position of the inner support (3).

2. The on-pile test apparatus for a self-sufficient energy detector according to claim 1, characterized in that, The outer support (2) includes multiple annular support units (21) spaced apart along the axial direction. The standard self-powered detector (4) is inserted and fixed in the multiple annular support units (21) to form the main support structure of the outer support (2). The crossbeam (22) is welded on the lowest annular support unit (21).

3. The on-pile test apparatus for a self-sufficient energy detector according to claim 2, characterized in that, The ring-shaped support unit (21) has a mounting hole (211) for the standard self-powered detector (4) to pass through. The port of the mounting hole (211) extends to form two symmetrical and elastic clamping rings (212). The two clamping rings (212) clamp the standard self-powered detector (4) passing through the mounting hole (211), so as to realize the quick assembly and disassembly and position fixation of the standard self-powered detector (4) and the ring-shaped support unit (21).

4. The on-pile test apparatus for a self-sufficient energy detector according to claim 1, characterized in that, The lower end of the inner support (3) is provided with a spherical contact (31), and the upper surface of the crossarm (22) is provided with a conical positioning groove (221) that is adapted to the spherical contact (31). When the inner support (3) is inserted into the inner cavity of the outer support (2), the spherical contact (31) abuts against the bottom of the conical positioning groove (221), thereby realizing the radial automatic centering and axial positioning of the inner support (3) and allowing the inner support (3) to rotate freely around the spherical contact (31).

5. The on-pile test apparatus for a self-sufficient energy detector according to claim 1 or 4, characterized in that, The top of the outer support (2) is provided with a support ring (23). The support ring (23) is fixedly connected to the uppermost structure of the outer support (2) through several connecting rods (24). The outer diameter of the support ring (23) is larger than the inner diameter of the port of the test dry channel (1) and is used to abut against the port of the test dry channel (1) to prevent the outer support (2) from falling into the test dry channel (1) as a whole.

6. The on-pile test apparatus for a self-sufficient energy detector according to claim 5, characterized in that, The inner support (3) extends upward to form a cylindrical guide rod (33). A limit ring (34) is provided on the guide rod (33). A quick-operation limit structure (35) is installed on the support ring (23). When the inner support (3) is inserted into the inner cavity of the outer support (2), the limit structure (35) is operated to act on the limit ring (34) to limit the axial displacement of the inner support (3) relative to the outer support (2). The guide rod (33) extends upward through the limit structure (35), and its top end is used to connect the inner support (3) hoisting line.

7. The on-pile test apparatus for a self-sufficient energy detector according to claim 6, characterized in that, The limiting structure (35) includes a base (351) fixedly installed on the support ring (23). The base (351) has a sliding hole (352) extending radially along the support ring (23). A cylindrical latch (353) passes through the sliding hole (352). The base (351) has a spring (354) that acts on the latch (353) to make the latch (353) slide towards the center of the support ring (23). A limiting protrusion (355) is formed on the side of the latch (353) away from the center of the support ring (23). A limiting groove (356) adapted to the limiting protrusion (355) is opened on the inner wall of the sliding hole (352). When the limiting protrusion (355) is inserted into the limiting groove (356), the end of the latch (353) is located above the limiting ring (34), which restricts the upward axial displacement of the inner support (3) within the outer support (2).

8. The on-pile test apparatus for a self-sufficient energy detector according to claim 6, characterized in that, The guide rod (33) has an axially through wiring cavity (331) inside, and a wire hole (332) communicating with the wiring cavity (331) is provided on its side wall. The signal cable of the self-powered detector (5) to be tested, which is installed on the inner bracket (3), is introduced into the wiring cavity (331) through the wire hole (332) and led out from the top of the guide rod (33).

9. The on-pile test apparatus for a self-sufficient energy detector according to claim 1, characterized in that, The outer support (2) and the inner support (3) are respectively equipped with a first thermocouple (6) and a second thermocouple (7). The first thermocouple (6) and the second thermocouple (7) are used to monitor the temperature of the microenvironment where the standard self-powered detector (4) and the self-powered detector under test (5) are located.

10. A method for on-pile calibration of a self-powered detector based on the device according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Insert the outer bracket (2) with the standard self-powered detector (4) into the test dry channel (1) and fix it. Insert the inner bracket (3) with the self-powered detector (5) to be tested into the inner cavity of the outer bracket (2) until the lower end of the inner bracket (3) contacts and positions the crossbeam (22). S2. After the reactor power stabilizes, drive the inner support (3) to rotate at a constant speed in the radial plane at least one revolution relative to the outer support (2) through the inner support hoisting line. During the rotation, pause at multiple equiangular intervals. After the signal stabilizes, synchronously record the output current of each standard self-powered detector (4) and the self-powered detector under test (5). S3. Calculate the arithmetic mean of the output current of each self-powered detector (5) at all recorded positions within one rotation, and use it as its average response current. Based on the output current of the standard self-powered detector (4) and its known sensitivity, calculate and deduce the theoretical average neutron flux rate of the test dry channel (1) in the radial plane of the inner support (3). S4. Divide the average response current of each self-powered detector (5) under test by the corresponding theoretical average neutron fluence rate to obtain the calibration sensitivity of each self-powered detector (5) under test.

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