Heating device for circumferential non-uniform thermal destructive test of nuclear fuel rod cladding

Abstract

The utility model discloses a heating device for a circumferential non-uniform thermal destructive test of a nuclear fuel rod cladding, which is characterized by comprising an inner heating tube with the length matched with that of the cladding, a connector is arranged at the incoming end of the inner heating tube, and a plug is arranged at the outgoing end of the inner heating tube. Two linear electric heating wires which are arranged in the axial direction are arranged in the middle position in the inner heating tube in parallel at intervals in the diameter direction, and the two linear electric heating wires are the same in length but different in heating power specification. According to the utility model, the thermal instability of nuclear reaction during the working of the cladding can be better simulated to detect the thermal destruction performance of the cladding, and the quality safety of products can be better ensured.

Description

Technical Field

[0001] This utility model relates to the field of nuclear fuel rod cladding testing technology, specifically to a heating device for circumferential non-uniform thermal destructive testing of nuclear fuel rod cladding. Background Technology

[0002] With traditional resources facing gradual depletion, nuclear power generation using nuclear fuel is becoming increasingly promising. Nuclear fuel cladding is the sealed outer shell of nuclear fuel; because it is generally long and cylindrical, it is also called cladding tube or nuclear fuel rod cladding. Its function is to prevent the escape of fission products, avoid fuel corrosion by coolant, and effectively dissipate heat. It is the second safety barrier of a nuclear power plant; therefore, destructive performance quality testing of the cladding is particularly important during the production process.

[0003] Existing methods for testing the destructive performance of cladding typically involve introducing a high-temperature, high-pressure testing medium into the cladding to test its burst strength. Examples include a zirconium alloy cladding tube burst test energy storage measurement device and method disclosed in CN202311606401.7; a rapid pressure boosting burst system for nuclear fuel cladding tubes disclosed in CN202122268106.8; and a burst test device and method for nuclear fuel cladding tubes disclosed in CN202011052604.2, among other patents. However, due to the significant instability of nuclear fuel reactions, the cladding does not experience uniform thermal pressure impacts during actual operation; the temperature experienced by different parts varies. Additionally, some existing technologies use heating wires to heat the cladding while simultaneously introducing high-pressure gas into the cladding for testing. In this method, the heating wires are typically located inside the cladding and are heated uniformly, resulting in relatively lower testing costs. However, the impact of nuclear fuel reaction instability was still not considered, and the heating element is located inside the cladding, which can easily affect the internal ventilation and pressurization process.

[0004] Therefore, how to test the thermal destructive properties of the casing under non-uniform working conditions and better ensure its quality has become a problem that needs to be considered and solved by those skilled in the art. Utility Model Content

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by this utility model is: how to provide a heating device for circumferential non-uniform thermal destructive test of nuclear fuel rod cladding that can better simulate the thermal instability of nuclear reaction during cladding operation and detect its thermal destructive performance, so as to better ensure product quality and safety.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A circumferentially non-uniform thermal destructive test heating device for a nuclear fuel rod cladding, characterized in that it includes an internal heating tube with a length matching that of the cladding. A joint is provided at the access end of the internal heating tube, and a plug is provided at the outlet end. Two linear electric heating wires arranged axially in parallel are arranged at intervals in the middle of the internal heating tube along the diameter direction. The two linear electric heating wires have the same length but different rated heating powers. After the access ends of the two linear electric heating wires are each welded and fixed to a positive conductive metal wire, they are connected to the joint. The joint has two external DC positive input wires that are connected to the two positive conductive metal wires inside the joint. The outlet ends of the two linear electric heating wires are simultaneously welded to a negative conductive metal wire. The negative conductive metal wire is connected along the axis of the internal heating tube to the plug and is externally connected to a DC negative output wire.

[0008] In this way, when the circumferentially non-uniform thermal destructive test heating device for the nuclear fuel rod cladding is in use, the device is installed and fixed inside the cladding to be tested. Nitrogen is introduced into the inside of the cladding to form air pressure, and then DC power is used for heating. The two DC positive input wires are connected to the DC positive pole, and the single DC negative output wire is connected to the DC negative pole. Different voltages can be respectively connected, so that the two linear electric heating wires form two different heating powers. This enables the two sides of the cladding in the circumferential direction to withstand different amounts of heat and temperatures. After the test time ends, if no rupture or deformation is detected in the cladding, it is considered qualified. Therefore, this can better simulate the actual working conditions and detect the thermal destruction performance of the cladding when it withstands non-uniform heat shocks in the circumferential direction. Compared with the method of uniform heating, it can better improve the detection effect and the safety of the cladding.

[0009] Furthermore, the specifications of the two linear electric heating wires are Φ0.9 and Φ0.7 respectively. This can better improve the detection effect. During implementation, the electric heating wire uses a Cr20Ni80 electric heating wire, which has a large calorific value and can better ensure the test effect.

[0010] Furthermore, both the positive conductive metal wire and the negative conductive metal wire are copper wires. Copper wires are inexpensive and have good electrical conductivity.

[0011] Furthermore, the internal heating tube is a metal tube (preferably made of stainless steel during implementation). The two linear electric heating wires and the connected positive conductive metal wires are each inserted and fixed inside a magnesia tube. Magnesia powder is filled by powder filling between the inside and outside of the two magnesia tubes and between the magnesia tubes and the internal heating tube. Magnesia powder is filled by powder filling between the negative conductive metal wire and the internal heating tube.

[0012] In this way, the internal heating element, being a metal tube, facilitates heat conduction. Simultaneously, the internal magnesium oxide powder filling provides better insulation. By attaching magnesium oxide tubes to the outside of the two straight heating wires and the connected positive conductive metal wire before filling with powder, it is easy to position the two straight heating wires and the connected positive conductive metal wire, maintaining distance between them and between them and the external metal tubes, ensuring insulation, and preventing short circuits and leakage.

[0013] Furthermore, the plug is made of silicone rubber and is used to seal the end of the inner heating element. Using this material allows for better sealing and withstands high-temperature environments.

[0014] Furthermore, the connector includes a sleeve-shaped connector shell made of metal and a sealing material located inside. The outer surface of the connector shell is provided with two truncated cones that gradually decrease in size towards the connector outlet. The surface at the smallest diameter of the truncated cone is used for the insertion and positioning of the shell port. The middle diameter of the truncated cone is used for welding and fixing to the inserted shell port. The largest diameter of the truncated cone is used for the installation and positioning of the device itself.

[0015] In this way, when using the device, one end of the casing to be tested is inserted into the inner heating tube and positioned on the step surface at the minimum diameter of the truncated cone of the connector, connecting with the position at the middle diameter. Then, it is welded and sealed in place. The test is then conducted by creating pressure with nitrogen gas from the other end of the casing. Therefore, this method facilitates the installation and fixation of the casing to be tested. In practice, silicone rubber is used as the sealing material inside the connector.

[0016] In summary, this invention can better simulate the thermal instability of nuclear reactions during shell operation and detect its thermal destructive properties, thus better ensuring product quality and safety. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the heating device for the circumferential non-uniform thermal destructive test of nuclear fuel rod cladding used in this utility model. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings.

[0019] In specific implementation: a heating device for circumferential non-uniform thermal destructive testing of nuclear fuel rod cladding, see [reference needed]. Figure 1, including an internal heating tube 1 with a length matching the length of the cladding. A connector 2 is provided at the access end of the internal heating tube 1, and a plug 3 is provided at the outlet end. Two linear heating wires 4 arranged in parallel along the axial direction are spaced apart in the middle of the internal heating tube 1 in the diameter direction. The two linear heating wires 4 have the same length but different heating power specifications. After the access ends of the two linear heating wires 4 are each welded and fixed to a positive conductive metal wire 5, they are connected to the connector 2. The connector 2 has two external DC positive input wires 6 that are connected to the two positive conductive metal wires 5 inside the connector. The outlet ends of the two linear heating wires 4 are simultaneously welded to a negative conductive metal wire 7. The negative conductive metal wire 7 is connected along the axis of the internal heating tube to the plug 3 and is externally connected to a DC negative output wire 8.

[0020] In this way, when the circumferential non-uniform thermal destructive test heating device of the nuclear fuel rod cladding is in use, the device is installed and fixed inside the cladding to be tested. Nitrogen is introduced into the inside of the cladding to form air pressure, and then DC power is used for heating. The two DC positive input wires are connected to the DC positive pole, and the single DC negative output wire is connected to the DC negative pole. Different voltages can be respectively connected, so that the two linear heating wires form two different heating powers. This enables the two sides of the cladding in the circumferential direction to bear different amounts of heat and temperatures. After the test time ends, if no rupture or deformation is detected in the cladding, it is considered qualified. Therefore, this can better simulate the actual working conditions and detect the thermal destruction performance of the cladding when it withstands non-uniform heat impact in the circumferential direction. Compared with the method of uniform heating, it can better improve the detection effect and enhance the safety of the cladding.

[0021] Among them, the specifications of the two linear heating wires 4 are Φ0.9 and Φ0.7 respectively. This can better improve the detection effect. During implementation, the heating wire uses a Cr20Ni80 heating wire, which has a large calorific value and can better ensure the test effect.

[0022] Among them, both the positive conductive metal wire 5 and the negative conductive metal wire 7 are copper wires. Copper wires have low cost and good electrical conductivity.

[0023] Among them, the internal heating tube 1 is a metal tube (preferably made of stainless steel during implementation). The two linear heating wires 4 and the connected positive conductive metal wires 5 are respectively inserted and fixed inside a magnesia tube (not shown in the figure). Magnesia powder (not shown in the figure) is filled by powder injection inside and outside the two magnesia tubes and between the outside and the internal heating tube. Magnesia powder (not shown in the figure) is filled by powder injection between the negative conductive metal wire 7 and the internal heating tube 1.

[0024] In this way, the internal heating element, being a metal tube, facilitates heat conduction. Simultaneously, the internal magnesium oxide powder filling provides better insulation. By attaching magnesium oxide tubes to the outside of the two straight heating wires and the connected positive conductive metal wire before filling with powder, it is easy to position the two straight heating wires and the connected positive conductive metal wire, maintaining distance between them and between them and the external metal tubes, ensuring insulation, and preventing short circuits and leakage.

[0025] The plug 3 is made of silicone rubber and is used to seal the end of the inner heating element. Using this material allows for better sealing and withstands high-temperature environments.

[0026] The connector 2 includes a sleeve-shaped connector shell 9 made of metal and a sealing material inside. The outer surface of the connector shell 9 is provided with two truncated cones that gradually decrease in size towards the connector outlet. The surface at the smallest diameter of the truncated cone is used for the insertion and positioning of the shell port. The middle diameter of the truncated cone is used for welding and fixing to the inserted shell port. The largest diameter of the truncated cone is used for the installation and positioning of the device itself.

[0027] In this way, when using the device, one end of the casing to be tested is inserted into the inner heating tube and positioned on the step surface at the minimum diameter of the truncated cone of the connector, connecting with the position at the middle diameter. Then, it is welded and sealed in place. The test is then conducted by creating pressure with nitrogen gas from the other end of the casing. Therefore, this method facilitates the installation and fixation of the casing to be tested. In practice, silicone rubber is used as the sealing material inside the connector.

Claims

1. A heating device for a circumferentially non-uniform thermal destructive test of nuclear fuel rod cladding, characterized in that, It includes an inner heating element with a length matching that of the casing. The inner heating element has a connector at its inlet and a plug at its outlet. Two straight heating wires are arranged axially in parallel along the diameter direction in the middle of the inner heating element. The two straight heating wires are the same length but have different heating power specifications. Each of the two straight heating wires has a positive conductive metal wire welded to its inlet and then connected to the connector. The connector has two external DC positive input wires connected to the two positive conductive metal wires inside the connector. The outlets of the two straight heating wires are simultaneously welded to a negative conductive metal wire. The negative conductive metal wire is connected to the plug along the axis of the inner heating element and is externally connected to a DC negative output wire.

2. The heating device for circumferential non-uniform thermal destructive testing of nuclear fuel rod cladding according to claim 1, characterized in that: Both the positive and negative conductive metal wires are copper wires.

3. The heating device for circumferential non-uniform thermal destructive testing of nuclear fuel rod cladding according to claim 1, characterized in that: The internal heating element is a metal tube. Two straight heating wires and a connected positive conductive metal wire are each inserted into and fixed inside a magnesium oxide tube. The inside and outside of the two magnesium oxide tubes and the space between them and the internal heating element are filled with magnesium oxide powder. The space between the negative conductive metal wire and the internal heating element is also filled with magnesium oxide powder.

4. The heating device for circumferential non-uniform thermal destructive testing of nuclear fuel rod cladding according to claim 1, characterized in that: The plug is made of silicone rubber and is used to seal the end of the internal heating element.

5. The heating device for circumferential non-uniform thermal destructive testing of nuclear fuel rod cladding according to claim 1, characterized in that: The connector includes a sleeve-shaped connector shell made of metal and a sealing material inside. The outer surface of the connector shell is provided with two truncated cones that gradually decrease in size towards the connector outlet. The surface at the smallest diameter of the truncated cone is used for the insertion and positioning of the shell port. The middle diameter of the truncated cone is used for welding and fixing to the inserted shell port. The largest diameter of the truncated cone is used for the installation and positioning of the device itself.

Images