An in-pile auxiliary heating system for a test reactor

Abstract

This invention belongs to the field of irradiation technology for materials used in research reactors, and specifically relates to an auxiliary heating system within an irradiation device based on a test reactor. It includes a computer, a temperature transmitter, a PLC controller, and a temperature frequency converter. The computer is connected to the PLC controller, which transmits signals to the temperature transmitter and the temperature frequency converter. The clamping block assembly is installed inside the test device and connected to the temperature frequency converter and an external power supply. The temperature transmitter is connected to a temperature sensor within the test device. This invention aims to solve the problem of large axial temperature differences in the test section of the irradiation device, increase the effective axial height length of the irradiation test section, and increase the loading capacity of the irradiated sample, making full use of limited irradiation resources. It features a high-power, compact structure, and is suitable for installation within the irradiation test section, effectively mitigating the axial temperature difference within the test section.

Description

Technical Field

[0001] This invention relates to the field of materials irradiation technology, and more specifically to an auxiliary heating system within an irradiation device based on a test reactor. Background Technology

[0002] Irradiation testing plays a crucial role in the development of the nuclear industry, and in-reactor irradiation verification is an essential step in the research and development of new nuclear materials and fuels. The High Flux Engineering Test Reactor (HFETR) has undertaken more than 90% of the irradiation testing tasks for the Nuclear Power Institute.

[0003] The HFETR has a high neutron flux rate within its channels, with the fast neutron flux rate in the inner single channel reaching the order of 10¹⁴, which is highly advantageous for quickly achieving the target flux and shortening the experimental cycle. However, because the neutron flux in the HFETR core exhibits a cosine distribution along the axial direction, and the heat release rate of the inner channel material is close to 7 W / g, the power of a single irradiation device test section can even reach 30 kW. This results in an axial temperature difference of 50–100 °C, far exceeding the temperature requirements for irradiation experiments. To achieve the technical specifications for irradiation experiment temperature, the effective length of the irradiation test section should be controlled within 400 mm, but the active section length of the 493 reactor reaches 1000 mm, leading to a significant waste of irradiation data.

[0004] To increase the axial space utilization of the irradiation device's test section, a high-power micro-heating device is installed on the extended irradiation test section. This effectively smooths out the axial temperature difference within the test section, increasing the sample loading capacity by 30-50%, resulting in significant economic benefits. Simultaneously, the addition of the high-power micro-heating device significantly improves the temperature control capability of the irradiation test device, reducing its reliance on stepped clamps, air gap structures, and inert gas temperature control. Consequently, the required machining precision for the irradiation device will also decrease, leading to a reduction in manufacturing costs.

[0005] To increase the axial space of the irradiation device's test section and improve the utilization rate of irradiation resources, a high-power micro-heating device is installed on the extended irradiation test section. This effectively smooths out the axial temperature difference within the test section, increasing the sample loading capacity by 30-50%. For irradiation experiments with a large number of samples, the increased sample loading capacity can shorten the irradiation test cycle by nearly half, resulting in significant economic benefits. Simultaneously, the addition of the high-power micro-heating device to the test section greatly improves the temperature control capability of the irradiation device, reducing its reliance on stepped clamps, air gap structures, and inert gas temperature control. Consequently, the required machining precision of the irradiation device will also decrease, leading to a reduction in manufacturing costs.

[0006] This project aims to design a high-power, compact heating device suitable for installation within the irradiation test section to flatten the axial temperature difference within the test section. The goal is to address the large axial temperature difference in the irradiation device's test section by increasing the effective axial height of the test section, significantly increasing the load capacity of irradiated samples, and making full use of limited irradiation resources. Furthermore, based on temperature information obtained from a temperature measurement system, this project will enable automatic control of the axial temperature difference in the irradiation test. Summary of the Invention

[0007] The purpose of this invention is to design a high-power, compact heating device suitable for installation within an irradiation test section to flatten the axial temperature difference within the test section. This aims to address the large axial temperature difference in the irradiation test section by increasing the effective axial height of the irradiation test section, significantly increasing the loading capacity of the irradiated sample, and making full use of limited irradiation resources. Furthermore, based on temperature information obtained from a temperature measurement system, this invention enables automatic control of the axial temperature difference in the irradiation test.

[0008] The technical solution of the present invention is as follows: an auxiliary heating system for an irradiation device based on a test reactor, comprising a computer, a temperature transmitter, a PLC controller, and a temperature frequency converter, and further comprising a test device and a clamping block assembly. The computer is connected to the PLC controller, and the PLC controller transmits signals to the temperature transmitter and the temperature frequency converter. The clamping block assembly is installed inside the test device and connected to the temperature frequency converter and an external power supply. The temperature transmitter is connected to a temperature sensor inside the test device. The experimental apparatus includes an inlet nozzle, an outlet nozzle, a cage, an inlet pipe, a flange, a transition pipe, a protective pipe, an upper cover, an irradiation tank, an upper pad, clamping blocks, a neutron temperature detector, a lower pad, a lower cover, a heating element assembly, and a sample. The upper cover, the irradiation tank, and the lower cover form a sealed space. The inlet pipe passes through the upper cover and extends into the bottom of the irradiation tank. The upper end of the inlet pipe passes through the flange, and the inlet nozzle is welded to the top. The protective pipe is welded to the upper cover and communicates with the irradiation tank. A transition pipe is welded to the upper end of the protective pipe, and a transition pipe is welded to the lower end face of the flange. A cage is welded to the upper end face of the flange. The outlet nozzle passes through the cage and is welded to the flange, communicating with the irradiation tank. The clamping blocks are axially stacked and sequentially installed inside the irradiation tank, with upper and lower pads used for positioning at both ends. The neutron temperature detector and the sample are arranged in the middle of the clamping block, and the heating element assembly is distributed in the axial position of the clamping block.

[0009] The heating element assembly includes electrodes, a heating element, and a casing. The electrodes are located at the ends of the heating element and are divided into positive and negative electrodes. The entire heating element is installed inside the casing, and the inner wall of the casing and the heating element are isolated by an insulator.

[0010] The heating element is a column with a central through hole, and axial grooves are machined around the column, giving it a labyrinthine structure.

[0011] The heating element is square and has a labyrinth structure inside.

[0012] In the radial direction of the heating element end face, the labyrinth structure is a multi-layered structure.

[0013] In the heating element assembly, the resistivity of the heating element is greater than 13 μΩm.

[0014] The casing material is stainless steel.

[0015] The end face of the heating element assembly has an arc-shaped structure and a square structure; the entire heating element assembly is implanted inside the clamping block.

[0016] The heating element components are evenly distributed along the axial position of the clamping block.

[0017] The outer edge of the clamping block forms an annular cavity with the inner wall of the irradiation tank.

[0018] The thickness of the cavity is 1.1~0.45mm.

[0019] The clamping block has holes that match the shape and structure of the sample, neutron temperature detector and heating element assembly, and its outer wall is in close contact with the inner wall of the clamping block hole.

[0020] The heating element 152 is made of carbon material.

[0021] The significant advantage of this invention lies in its ability to solve the technical problem of providing a high-power, compact heating device suitable for installation within an irradiation test section to flatten the axial temperature difference within the test section. This addresses the issue of large axial temperature differences in the irradiation device's test section by increasing the effective axial height of the test section, significantly increasing the loading capacity of the irradiated sample, and fully utilizing limited irradiation resources. Furthermore, based on temperature information obtained from a temperature measurement system, this invention enables automatic control of the axial temperature difference in the irradiation test.

[0022] In practical use, the present invention has demonstrated the following beneficial effects: This invention features high power, compact structure, and suitability for installation within irradiation test sections. It can be flexibly arranged in the low-temperature region of the irradiation test section, fully flattening the axial temperature difference of the irradiation test section.

[0023] The heating element assembly of this invention is designed with high resistivity material and a labyrinth structure, which greatly improves the resistance value of the heating element, significantly increases the thermal power, effectively reduces the space occupied by the heating element in the device, and increases the loading capacity of the sample; at the same time, the heating element adopts a material armor structure, which improves the high temperature resistance and safety of the heating element.

[0024] This invention designs a matching temperature control system with closed-loop temperature control capability, which can automatically adjust the temperature according to the temperature setting to keep the temperature of the irradiation test section stable within a certain range. Attached Figure Description

[0025] Figure 1 : A schematic diagram of the auxiliary heating system of the present invention; Figure 2 : A schematic diagram of the overall structure of the present invention; Figure 3 : Schematic diagram of the clamping block assembly structure; Figure 4 : Schematic diagram of the clamping block structure; Figure 5 Schematic diagram of the heating element assembly; Figure 6 Schematic diagram of the heating element structure; Figure 7 Schematic diagram of the heating element assembly; Figure 8 Schematic diagram of the arc-shaped heating element clamping block assembly; Figure 9 : Schematic diagram of the circular arrangement clamping block assembly for the sample.

[0026] Symbol explanation: 1. Inlet nozzle; 2. Outlet nozzle; 3. Rag cage; 4. Inlet pipe; 5. Flange; 6. Transition pipe; 7. Protective pipe; 8. Top cover; 9. Irradiation vessel; 10. Upper pad; 11. Clamping block; 12. Neutron temperature detector; 13. Lower pad; 14. Lower cover; 15. Heating element assembly; 16. Sample; 21. Computer; 22. Temperature transmitter; 23. PLC controller; 24. Temperature frequency converter; 25. Testing apparatus; 26. Clamp assembly 151. Electrode; 152. Heating element; 153. Sheath Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, where there is no conflict, the embodiments and features described in these embodiments can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0029] An auxiliary heating system for an irradiation device based on a test reactor includes a computer 21, a temperature transmitter 22, a PLC controller 23, and a temperature frequency converter 24. It also includes a test device 25 and a clamping block assembly 26. The computer 21 is connected to the PLC controller 23, which can transmit signals with the temperature transmitter 22 and the temperature frequency converter 24. The clamping block assembly 26 is installed inside the test device 25 and connected to the temperature frequency converter 24 and an external power supply. The temperature transmitter 22 is connected to a temperature sensor inside the test device 25. The experimental apparatus 25 includes an inlet nozzle 1, an outlet nozzle 2, a cage 3, an inlet pipe 4, a flange 5, a transition pipe 6, a protective pipe 7, an upper cover 8, an irradiation tank 9, an upper pad 10, a clamping block 11, a neutron temperature detector 12, a lower pad 13, a lower cover 14, a heating element assembly 15, and a sample 16. The upper cover 8, the irradiation tank 9, and the lower cover 14 form a sealed space. The inlet pipe 4 passes through the upper cover 8 and extends into the bottom of the irradiation tank 9. Its upper end passes through the flange 5, and the inlet nozzle 1 is welded to the top. The protective pipe 7 is welded to the upper cover 8 and communicates with the irradiation tank 9. The transition pipe 6 is welded to the upper end of the protective pipe 7. The transition pipe 6 is welded to the lower end face of the flange 5, and the cage 3 is welded to the upper end face. The outlet nozzle 2 passes through the cage 3 and is welded to the flange 5, communicating with the irradiation tank 9. The clamping blocks 11 are axially stacked and sequentially installed inside the irradiation tank 9, and are positioned at both ends by the upper pad 10 and the lower pad 13.

[0030] The neutron temperature detector 12 and the sample 16 are arranged in the middle of the clamp 11, and the heating element assembly 15 is evenly distributed in the axial position of the clamp 11. The heating element assembly has wires leading out from the top of the test device 25 and connected to the temperature frequency converter 24. The computer 21 can control the thermal power of the heating element assembly 15 through the temperature frequency converter 24. A temperature sensor is connected to the neutron temperature detector 12. The temperature sensor leads out of the test device 25 and is connected to the temperature transmitter 22. The temperature transmitter 22 feeds back the temperature of the clamp 11 and the sample 16 to the PLC controller 23. The PLC controller 23 compares the temperature with the set value and then determines whether to control the thermal power of the heating element assembly 15 through the temperature frequency converter 24, forming a closed-loop temperature control system.

[0031] The heating element assembly 15 includes an electrode 151, a heating element 152, and a casing 153. The electrode 151 is located at the end of the heating element 152 and is divided into positive and negative electrodes, which are connected through the heating element 152 itself. The heating element 152 is armored, and the entire heating element 152 is installed inside the casing 153. The casing 153 encloses the entire heating element 152 to form a sealed cavity, and the inner wall of the casing 153 and the heating element 152 are isolated by an insulator. The wires connected to the heating element are also armored with stainless steel to increase the strength and high-temperature resistance of the wires.

[0032] The outer edge of the clamp 11 forms an annular cavity with the inner wall of the irradiation tank 9, and the thickness of the cavity is 1.1~0.45mm. During the test, pure inert gas is filled into the annular cavity. The inert gas is composed of two gases with very different thermal conductivity. The inert gas fills the annular cavity, forming a gas insulation layer to ensure that the temperature of the sample 16 reaches the test index. At the same time, the thermal conductivity of the gas insulation layer can be changed by changing the proportion of inert gas, thereby achieving the purpose of controlling the temperature of the sample 16.

[0033] The end face of the heating element assembly 15 can be an arc-shaped structure or a square structure; the heating element assembly 15 can be implanted inside the clamping block 11, so that the entire clamping block 11 acts as a heating element. The clamping block into which the heating element assembly 15 is implanted can be designed according to the structure of the sample 16, and holes can be machined in the clamping block 11 according to the shape of the sample 16.

[0034] The heating element assembly 15 can be installed at the center of the clamping block 11, and the sample 16 is evenly distributed along the axial direction of the clamping block 11. The arrangement and design structure of the heating element assembly 15 can be flexibly adjusted according to design requirements and test temperature indicators.

[0035] The clamping block 11 has holes that match the shape and structure of the sample 16, the neutron temperature detector 12, and the heating element assembly 15, and its outer wall is in close contact with the inner wall of the hole in the clamping block 11. In order for heat to be smoothly discharged or transferred, the outer walls of the sample 16, the neutron temperature detector 12, and the heating element assembly 15 must be in close contact with the inner wall of the hole in the clamping block.

[0036] The heating element 152 is a column with a through hole in the center. The column is axially machined with grooves around its perimeter, and the column has a labyrinth structure, connecting one electrode to another. The labyrinth structure is mainly to increase the length of the conductor and, under the premise of the same volume, to increase the resistance value as much as possible, so that the heating element 152 can obtain higher electrical power.

[0037] In the heating element assembly 15, the heating element 152 is made of a high resistivity material with a resistivity greater than 13 μΩm, the shell 153 is made of stainless steel, and the insulating material is magnesium oxide; the heating element 152 material should be a high-power material, and the electrode material should be heat-resistant.

[0038] When the heating element 152 is arc-shaped or square, its interior also has a labyrinth structure. The arc-shaped or square cross-section of the heating element 152 is also to accommodate the needs of the clamping block 11 and to meet the requirements of increasing thermal power. The square or arc shape is also cut into a labyrinth structure along the edges. According to design requirements, the labyrinth structure is processed in multiple layers radially on the end face of the heating element 16, with at least two layers. The high resistivity material of the heating element 152 is a carbon material. Carbon material, as an alternative material for the heating element 152, has the advantages of high resistivity, high temperature resistance, and good processing performance.

[0039] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. An auxiliary heating system for an irradiation device based on a test reactor, comprising a computer (21), a temperature transmitter (22), a PLC controller (23), and a temperature frequency converter (24), characterized in that: It also includes a test apparatus (25); the test apparatus (25) includes an inlet nozzle (1), an outlet nozzle (2), a cage (3), an inlet pipe (4), a flange (5), a transition pipe (6), a protective pipe (7), an upper end cover (8), an irradiation vessel (9), an upper pad (10), a clamping block (11), a neutron temperature detector (12), a lower pad (13), a lower end cover (14), a heating element assembly (15), and a sample (16); the upper end cover (8), the irradiation vessel (9), and the lower end cover (14) form a sealed space; the inlet pipe (4) passes through the upper end cover (8). The air inlet pipe (4) extends into the bottom of the irradiation tank (9), passes through the flange (5) at the top, and is welded to the top with the air inlet nozzle (1); the protective pipe (7) is welded to the upper end cover (8) and communicates with the irradiation tank (9), the upper end of the protective pipe (7) is welded with the transition pipe (6), the lower end face of the flange (5) is welded with the transition pipe (6), the upper end face is welded with the rat cage (3), the air outlet nozzle (2) passes through the rat cage (3) and is welded to the flange (5) and communicates with the irradiation tank (9); the clamping blocks (11) are stacked axially and installed sequentially inside the irradiation tank (9), and the two ends are positioned by the upper pad block (10) and the lower pad block (13); The neutron temperature detector (12) and the sample (16) are arranged in the middle of the clamp (11), and the heating element assembly (15) is distributed in the axial position of the clamp (11). The heating element assembly has wires leading out from the top of the test device (25) and connected to the temperature inverter (24). The computer (21) controls the thermal power of the heating element assembly (15) through the temperature inverter (24). A temperature sensor is connected to the neutron temperature detector (12). The temperature sensor leads out from the test device (25) and connects to the temperature transmitter (22). The temperature transmitter (22) feeds back the temperature of the clamp (11) and the sample (16) to the PLC controller (23). The PLC controller (23) determines whether to control the thermal power of the heating element assembly (15) through the temperature inverter (24) by comparing it with the set value, thus forming a closed-loop system for temperature control. The heating element assembly (15) includes an electrode (151), a heating element (152), and a casing (153). The electrode (151) is located at the end of the heating element (152) and is divided into positive and negative electrodes. The entire heating element (152) is installed inside the casing (153), and the inner wall of the casing (153) and the heating element (152) are isolated by an insulator. The heating element (152) is a column with a through hole in the center, and the column is axially machined with grooves around its perimeter, forming a labyrinth structure; or the heating element (152) is square, with a labyrinth structure inside, and the labyrinth structure is multi-layered in the radial direction of the end face of the heating element (152). The outer edge of the clamp (11) and the inner wall of the irradiation tank (9) form an annular cavity; the thickness of the cavity is 0.45~1.1mm; The clamp (11) has holes that match the shape and structure of the sample (16), neutron temperature detector (12) and heating element assembly (15). The outer walls of the sample (16), neutron temperature detector (12) and heating element assembly (15) are all in close contact with the inner wall of the holes in the clamp (11).

2. The auxiliary heating system within an irradiation device based on a test reactor as described in claim 1, characterized in that: In the heating element assembly (15), the resistivity of the heating element (152) is greater than 13 μΩm.

3. The auxiliary heating system within an irradiation device based on a test reactor as described in claim 1, characterized in that: The casing (153) is made of stainless steel.

4. An auxiliary heating system for an irradiation device based on a test reactor as described in any one of claims 1 to 3, characterized in that: The heating element (152) is a carbon material.

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