Power transient irradiation device suitable for chip element and power partition measurement method

Abstract

The invention discloses a power transient irradiation device suitable for sheet elements and a power partition measurement method, and relates to the technical field of reactor irradiation, the power transient irradiation device comprises a square box, an inner cavity of the square box is an inner flow channel for cooling water to pass through, and a plurality of sheet fuel elements are sequentially and uniformly distributed in the inner flow channel from bottom to top at intervals; the plurality of spiral tube helium screens are in one-to-one correspondence with the plurality of sheet-shaped fuel elements, the spiral tube helium screens are wound on the outer side of the square box in a folding manner, and the adjacent spiral tube helium screens are communicated with each other; the two ends of the fuel section of each sheet-shaped fuel element are located between the two ends of the corresponding spiral pipe helium screen. An axial multilayer sheet-shaped fuel arrangement scheme is adopted, a plurality of sheet-shaped fuel elements can be carried at the same time, and each layer of fuel elements can be matched with spiral tube helium screens with different pipeline inner diameters and winding screw pitches, so that the fuel elements at different positions correspond to different power variation amplitudes; therefore, the power transient test capability and the test parameter range of the device can be greatly expanded.

Description

Technical Field

[0001] The invention relates to the technical field of stack irradiation, and in particular to a power transient irradiation device suitable for sheet elements and a power partition measurement method. Background Art

[0002] The performance of pressurized water reactor fuel elements is directly related to the safety and economy of the reactor. Carrying out in-pile irradiation tests on fuel elements is a key link in the research and development and design of fuel elements. Power transient irradiation tests on fuel elements are generally carried out in research reactors using special power transient irradiation test equipment; by changing the power of the fuel elements in a short period of time, the performance parameters and safety margins of the fuel elements are verified. In order to conduct power transient irradiation tests on pressurized water reactor fuel elements in research reactors, some foreign research reactors, such as the HBWR reactor in Norway, the BR2 reactor in Belgium, the R2 reactor in Sweden and the JMTR reactor in Japan, use helium-3 gas loops as power regulating devices for fuel elements. By changing the gaseous neutron poison ( 3 He gas) to effectively regulate the irradiation power of the test fuel element.

[0003] The helium shield of the helium-3 gas circuit and some of the helium pipelines connected to it are located in the active area of ​​the research reactor core; 3 He gas absorbs thermal neutrons in the reactor, producing tritium ( 3 H). Tritium is an isotope of hydrogen. Tritium in gaseous state has strong permeability. Tritium at higher temperatures can easily penetrate containers made of metal materials and leak into the environment. The permeability of tritium increases sharply as its temperature rises.

[0004] Since the sheet fuel element is a thin plate structure with a rectangular cross-section, the traditional helium shield structure greatly reduces the range of fuel element power variation. It is necessary to develop an innovative helium shield design to achieve a significantly increased fuel power transient test. On the other hand, since the power of fuel elements at different positions in a single test varies greatly, the traditional heat balance method can only measure the total heat release power of multiple fuel elements. Therefore, it is necessary to develop a corresponding method to achieve real-time measurement of the power of fuel elements at different positions during the fuel power transient test. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the present invention aims to provide a power transient irradiation device and a power partition measurement method suitable for sheet elements. An axial multi-layer sheet fuel arrangement scheme is adopted, and multiple sheet fuel elements can be carried at the same time. Each layer of fuel elements can be matched with a spiral tube helium screen with different pipe inner diameters and winding pitches to achieve different power variation amplitudes corresponding to fuel elements in different positions, thereby greatly expanding the power transient test capability and test parameter range of the device.

[0006] The present invention is achieved through the following technical solutions:

[0007] Power transient irradiation device for chip components, including:

[0008] A square box, wherein the upper and lower ends of the square box are open, the inner cavity of the square box is an inner flow channel for cooling water to pass through, and a plurality of sheet-like fuel elements are evenly spaced in the inner flow channel from bottom to top, and the plurality of sheet-like fuel elements are placed vertically and located on the same vertical plane;

[0009] A plurality of spiral tube helium screens, wherein the plurality of spiral tube helium screens correspond to the plurality of sheet-like fuel elements one by one, and the spiral tube helium screens are folded around the outside of the square box, and the adjacent spiral tube helium screens are connected to each other; the lower end of the spiral tube helium screen at the bottom is connected to the helium inlet pipe, and the upper end of the spiral tube helium screen at the top is connected to the helium outlet pipe;

[0010] Both ends of the fuel segment of the sheet-like fuel element are located between the corresponding ends of the spiral tube helium shield.

[0011] Compared with the prior art, the helium shield of the helium-3 gas circuit and part of the helium pipeline connected thereto are located in the active area of ​​the research reactor core; 3 He gas absorbs thermal neutrons in the reactor, producing tritium ( 3 H). Tritium is an isotope of hydrogen. Tritium in gaseous state has a strong permeability; tritium at a higher temperature can easily penetrate containers made of metal materials and then leak into the environment. The permeability of tritium increases sharply with the increase of its own temperature; and because the sheet fuel element is a thin plate structure with a rectangular cross-section, the power variation range of the fuel element is greatly reduced by the traditional helium screen structure, and because the power of fuel elements at different positions in a single test is quite different, the traditional heat balance method can only measure the total heat release power of multiple fuel elements. The present invention provides a power transient irradiation device suitable for sheet elements, which adopts an axial multi-layer sheet fuel arrangement scheme, can carry multiple sheet fuel elements at the same time, and each layer of fuel elements can be equipped with a spiral tube helium screen with different pipe inner diameters and winding pitches to achieve different power variation ranges for fuel elements at different positions, thereby greatly expanding the power transient test capability and test parameter range of the device.

[0012] In the specific scheme, a square box, a spiral tube helium screen, a helium inlet pipe and a helium outlet pipe are included. The spiral tube helium screen is folded around the outside of the square box in a spiral direction. At this time, several spiral tube helium screens, such as the first spiral tube helium screen, the second spiral tube helium screen and the third spiral tube helium screen, are connected to each other. The gas pipelines of the spiral tube helium screens at different positions can be preferably connected by welding. The lower end of the third spiral tube helium screen at the bottom is connected to the helium inlet pipe, and the upper end of the first spiral tube helium screen at the top is connected to the helium outlet pipe. In this way, helium can be filled into several spiral tube helium screens ( 3 He gas), helium-3 gas enters from the helium inlet pipe, flows through a number of spiral tube helium screens, and finally flows out through the helium outlet pipe; in addition, there is an inner cavity inside the square box, that is, an inner flow channel for cooling water to pass through, and a number of sheet-like fuel elements are evenly spaced in sequence along the axial direction of the inner flow channel, that is, N sheet-like fuel elements are arranged in a row vertically, and the array of sheet-like fuel elements is in the shape of a thin rectangular parallelepiped, and the shape and position are kept fixed by the corresponding fixed structure, so that the cooling water entering the square box will be divided into two parts by the sheet-like fuel elements, and after being heated by the fuel elements, they will re-converge at the top of the sheet-like fuel element array and enter the inner flow channel in the middle joint area; each layer of sheet-like fuel elements corresponds to an independent spiral tube helium screen, so that a large power jump of the sheet-like fuel elements can be achieved through the spiral tube helium screen; in addition, the spiral tube helium screen corresponding to each layer of sheet-like fuel elements can independently set the diameter of the pipeline and the pitch of the spiral tube, so that under the same helium-3 gas pressure change range, the sheet-like fuel elements at different positions can achieve different power change ranges. Wherein, both ends of the fuel segment of the sheet-like fuel element are located between the corresponding ends of the spiral tube helium shield, and preferably, the axial position and length of the spiral tube helium shield are the same as those of the corresponding sheet-like fuel element.

[0013] The above scheme aims to achieve: the axial multi-layer sheet fuel arrangement scheme is adopted, which can carry multiple sheet fuel elements at the same time, thereby improving the utilization rate of the irradiation space in the irradiation channel; while the spiral tube helium screen is used to achieve a substantial jump in the sheet fuel power, each layer of fuel elements can be equipped with a spiral tube helium screen with different pipe inner diameters and winding pitches, so that different positions of fuel elements correspond to different power change amplitudes, thereby greatly expanding the power transient test capability and test parameter range of the device. In addition, the spiral tube helium screen is located outside the inner flow channel for cooling the sheet fuel element, which reduces the influence of the heat release of helium-3 gas and its helium screen structural materials on the measurement of the fuel heat release power, and improves the accuracy of the measurement of the heat release power of the sheet fuel element. The spiral tube helium screen does not contact the higher temperature cooling water for cooling the sheet fuel element, which reduces the temperature of the helium pipeline and the tritium helium gas contained in the pipeline to a certain extent, thereby helping to reduce the penetration and leakage of tritium.

[0014] In order to serve as a pressure boundary and form a coolant channel, a pressure tube is also included. The square box and the spiral tube helium shield are both located in the chamber of the pressure tube. The pressure tube has a cooling water inlet, and the cooling water inlet is located above the spiral tube helium shield. The lower end of the square box is connected to the bottom of the pressure tube, and the upper end of the square box is connected to the cooling water outlet. In this scheme, the pressure tube is a thick-walled cylindrical structure made of stainless steel material, which serves as a pressure boundary and accommodates cooling water with typical pressurized water reactor environmental parameters. In this way, cooling water can flow in from the upper cooling water inlet, flow downward along the outer flow channel, thereby cooling the pressure tube and the spiral tube helium shield, and then return upward at the bottom of the pressure tube and the outer tube, so as to pass through the inner flow channel, flush and cool the sheet-like fuel elements, and then flow out from the coolant outlet.

[0015] In order to completely separate the outer flow channel from the inner flow channel, a shunt pipe is also included, one end of which is connected to the upper end of the square box through an intermediate joint, and the other end of the shunt pipe passes through the pressure pipe.

[0016] In order to reduce heat transfer, a protection tube is also included. The pressure tube and the protection tube are coaxial and arranged in sequence from the inside to the outside. The chamber between the inner side of the protection tube and the outer side of the pressure tube is a nitrogen chamber. In this solution, the protection tube is located outside the pressure tube and is also a cylindrical structure; there is a nitrogen chamber between the two, which is filled with nitrogen at normal pressure and is connected to the nitrogen inlet and the nitrogen outlet respectively.

[0017] In order to reduce the heat exchange between cooling water in different flow channels inside and outside the tube and provide a measurement lead channel, the diverter tube and the square box both adopt a first double-layer tube structure, and the gap in the first double-layer tube structure is filled with nitrogen.

[0018] In order to further prevent the tritium in the spiral tube helium shield and the connected helium pipeline from penetrating and leaking into the cooling water, the spiral tube helium shield, the helium inlet pipe and the helium outlet pipe all adopt a second double-layer tube structure with a filling layer, and the second double-layer tube structure includes an inner tube, a sponge-like metal titanium tube filling layer and an outer tube from the inside to the outside; the inner tube and the outer tube are both made of stainless steel with a dense Al2O3 coating. In this solution, a helium pipeline with a double-layer stainless steel tube structure with an interlayer is adopted, and the double-layer tube is designed with Al2O3 coating. The inner tube contains tritium-containing helium, which can prevent the tritium in the helium shield and the connected helium pipeline from penetrating and leaking into the cooling water, thereby effectively reducing the radioactive hazards caused by tritium leakage.

[0019] In order to monitor the thermal neutron flux rate near different sheet fuel elements online, so as to accurately measure the relative power distribution of sheet fuel elements at different positions during the power transient test, a measuring head of a self-powered neutron detector is installed at the central area of ​​the wide side of each sheet fuel element, and the measuring heads of several self-powered neutron detectors are located in the square box. In this scheme, the self-powered neutron detector is preferably configured to be implanted in the hollow interlayer of the square box, and the number of detectors is consistent with the number of sheet fuel elements. Each detector corresponds to a layer of sheet fuel elements, and its installation position is close to the central area of ​​the wide side of the sheet fuel element. The self-powered neutron detector arranged in the device can monitor the thermal neutron flux rate near different sheet fuel elements online; so as to accurately measure the relative power distribution of sheet fuel elements at different positions during the power transient test.

[0020] In order to measure the temperature rise of the inner channel cooling water in the fuel area, a number of fuel section inlet thermocouples are arranged below the bottommost sheet fuel element; and a number of fuel section outlet thermocouples are arranged above the topmost sheet fuel element. By measuring the temperature rise of the inner channel cooling water in the test fuel area and using the cooling water flow measured by the external system connected to the device, the total heat release power of all sheet fuel elements can be obtained.

[0021] A further solution is a power partition measurement method for a power transient irradiation device suitable for a sheet element, comprising the following steps:

[0022] The inlet cooling water temperature at the lower end of the inner flow channel and the outlet cooling water temperature at the upper end are measured respectively to obtain the temperature rise of the cooling water in the test fuel area, and the cooling water flow rate is measured by an external system to obtain the total heat release power of all the sheet-like fuel elements;

[0023] The relative power distribution of each sheet-shaped fuel element is obtained by online measurement;

[0024] By using the relative power distribution of each sheet-like fuel element and combining it with the total heat release power, the power data of each sheet-like fuel element during the fuel power transient test can be measured in real time.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] 1) The power transient irradiation device and power partition measurement method suitable for sheet elements provided by the present invention adopt an axial multi-layer sheet fuel arrangement scheme, which can carry multiple sheet fuel elements at the same time, thereby improving the utilization rate of the irradiation space in the irradiation channel.

[0027] 2) The power transient irradiation device and power zone measurement method suitable for sheet elements provided by the present invention are equipped with a spiral tube helium screen with different pipe inner diameters and winding pitches for each layer of fuel elements, so as to achieve different power variation amplitudes corresponding to fuel elements in different positions; thereby greatly expanding the power transient test capability and test parameter range of the device.

[0028] 3) The power transient irradiation device and power partition measurement method suitable for sheet elements provided by the present invention utilize the traditional thermal balance method to measure the total heat release power of the fuel, and combine the relative power distribution data of different fuel elements obtained by online measurement of SPND at different positions to realize real-time independent measurement of the power of all fuel elements during the power transient test.

[0029] 4) The power transient irradiation device and power partition measurement method suitable for sheet elements provided by the present invention adopt a double-layer tube structure design for both the square box and the shunt tube, which effectively reduces the heat exchange of cooling water between the inner and outer flow channels; at the same time, the helium shield is located outside the square box, which reduces the influence of the heat release of helium-3 gas and its helium shield structural materials on the fuel heat release power measurement, thereby improving the accuracy of the heat release power measurement.

[0030] 5) The power transient irradiation device and power partition measurement method suitable for sheet elements provided by the present invention, wherein the helium screen is located in the pressure tube and is relatively close to the sheet fuel element, can effectively increase the variation range of the fuel power.

[0031] 6) The power transient irradiation device and power partition measurement method suitable for sheet elements provided by the present invention adopt a helium pipeline with a double-layer stainless steel tube structure with an interlayer, and the double-layer tube adopts an Al2O3 coating design, which can effectively reduce the penetration and leakage of tritium in the helium pipeline.

[0032] 7) The present invention can be applied to the design of in-pile device for a fuel power transient test loop using a helium-3 gas loop, and can ultimately be used to study power transient irradiation tests of sheet-like fuel elements in the reactor and partitioned power measurements of fuel elements at different positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0034] Figure 1 A schematic diagram of the structure of the power transient irradiation device provided by the present invention;

[0035] Figure 2An AA cross-sectional view of the power transient irradiation device provided by the present invention;

[0036] Figure 3 A BB cross-sectional view of the power transient irradiation device provided by the present invention;

[0037] Figure 4 This is a schematic structural diagram of the spiral tube helium screen provided by the present invention.

[0038] Marks and corresponding parts names in the attached drawings:

[0039] 1-protection tube; 2-nitrogen cavity; 3-pressure tube; 4-helical tube helium screen; 401-first helical tube helium screen, 402-second helical tube helium screen, 403-third helical tube helium screen; 5-square box; 6-sheet fuel element; 7-external flow channel; 8-internal flow channel; 9-shunt tube; 10-nitrogen inlet; 11-nitrogen outlet; 12-cooling water inlet; 13-cooling water outlet; 14-fuel section inlet thermocouple; 15-fuel section outlet thermocouple; 16-self-powered neutron detector; 17-helium outlet pipe; 18-helium inlet pipe. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0041] Example 1

[0042] This embodiment 1 provides a power transient irradiation device suitable for sheet components, such as Figure 1-Figure 4 As shown, including:

[0043] A square box 5, wherein the upper and lower ends of the square box 5 are open, and the inner cavity of the square box 5 is an inner flow channel 8 for cooling water to pass through, and a plurality of sheet-like fuel elements 6 are uniformly spaced in the inner flow channel 8 from bottom to top, and the plurality of sheet-like fuel elements 6 are placed vertically and located on the same vertical plane;

[0044] A plurality of spiral tube helium shields 4, wherein the plurality of spiral tube helium shields 4 correspond to the plurality of sheet-like fuel elements 6 one by one, and the spiral tube helium shields 4 are folded around the outside of the square box 5, and the adjacent spiral tube helium shields 4 are connected to each other; the lower end of the spiral tube helium shield 4 at the bottom is connected to the helium inlet pipe 18, and the upper end of the spiral tube helium shield 4 at the top is connected to the helium outlet pipe 17;

[0045] Both ends of the fuel segment of the sheet-like fuel element 6 are located between the corresponding ends of the spiral tube helium shield 4 .

[0046] Compared with the prior art, the helium shield of the helium-3 gas circuit and part of the helium pipeline connected thereto are located in the active area of ​​the research reactor core; 3 He gas absorbs thermal neutrons in the reactor, producing tritium ( 3 H). Tritium is an isotope of hydrogen, and tritium in a gaseous state has a strong permeability; tritium at a higher temperature can easily penetrate containers made of metal materials and then leak into the environment. The permeability of tritium increases sharply with the increase of its own temperature; and because the sheet-like fuel element 6 is a thin plate structure with a rectangular cross-section, the power variation range of the fuel element for the traditional helium screen structure is greatly reduced, and because the power of the fuel elements at different positions in a single test is quite different, the traditional heat balance method can only measure the total heat release power of multiple fuel elements. The present invention provides a power transient irradiation device suitable for sheet-like elements, which adopts an axial multi-layer sheet fuel arrangement scheme, can carry multiple sheet-like fuel elements 6 at the same time, and each layer of fuel elements can be matched with a spiral tube helium screen 4 with different pipe inner diameters and winding pitches to achieve different power variation ranges corresponding to fuel elements at different positions, thereby greatly expanding the power transient test capability and test parameter range of the device.

[0047] In the specific scheme, a square box 5, a spiral tube helium screen 4, a helium inlet pipe 18 and a helium outlet pipe 17 are included. The spiral tube helium screen 4 is folded around the outside of the square box 5 in a spiral direction. At this time, a plurality of spiral tube helium screens 4, such as the first spiral tube helium screen 401, the second spiral tube helium screen 402 and the third spiral tube helium screen 403 are connected to each other. The gas pipelines of the spiral tube helium screens 4 at different positions can be preferably connected by welding. The lower end of the third spiral tube helium screen 403 at the bottom is connected to the helium inlet pipe 18, and the upper end of the first spiral tube helium screen 401 at the top is connected to the helium outlet pipe 17. In this way, helium can be filled into the plurality of spiral tube helium screens 4 ( 3He gas), helium-3 gas enters from the helium inlet pipe 18, flows through a plurality of spiral tube helium screens 4, and finally flows out through the helium outlet pipe 17; in addition, there is an inner cavity inside the square box 5, that is, an inner flow channel 8 for cooling water to pass through, and a plurality of sheet-like fuel elements 6 are uniformly spaced in sequence along the axial direction of the inner flow channel 8, that is, N sheet-like fuel elements 6 are arranged in a row vertically, and the array of sheet-like fuel elements 6 is in the shape of a thin rectangular parallelepiped, and the shape and position are fixed by the corresponding fixing structure, so that the cooling water entering the square box 5 will be divided into two parts by the sheet-like fuel elements 6, After the fuel element is heated, it re-converges at the top of the sheet fuel element 6 array and enters the inner flow channel 8 in the middle joint area; each layer of sheet fuel element 6 corresponds to an independent spiral tube helium shield 4, so that the sheet fuel element 6 can achieve a large power jump through the spiral tube helium shield 4; in addition, the spiral tube helium shield 4 corresponding to each layer of sheet fuel element 6 can independently set the diameter of the pipeline and the pitch of the spiral tube, so that the sheet fuel element 6 at different positions can achieve different power change ranges under the same helium-3 gas pressure change range. Among them, both ends of the fuel section of the sheet fuel element 6 are located between the corresponding ends of the spiral tube helium shield 4, and preferably the axial position and length of the spiral tube helium shield 4 are the same as those of the corresponding sheet fuel element 6.

[0048] The above scheme aims to achieve: adopting an axial multi-layer sheet fuel arrangement scheme, which can carry multiple sheet fuel elements 6 at the same time, thereby improving the utilization rate of the irradiation space in the irradiation channel; while realizing a substantial jump in the sheet fuel power through the spiral tube helium shield 4, each layer of fuel elements can be equipped with a spiral tube helium shield 4 with different pipe inner diameters and winding pitches, so as to realize different power variation amplitudes corresponding to fuel elements at different positions, thereby greatly expanding the power transient test capability and test parameter range of the device. In addition, the spiral tube helium shield 4 is located outside the inner flow channel 8 for cooling the sheet fuel element 6, reducing the influence of the heat release of helium-3 gas and its helium shield structural material on the measurement of the fuel heat release power, and improving the accuracy of the measurement of the heat release power of the sheet fuel element 6. The spiral tube helium shield 4 does not contact the high-temperature cooling water for cooling the sheet fuel element 6, which reduces the temperature of the helium pipeline and the tritium helium gas contained in the pipeline to a certain extent, thereby helping to reduce the penetration and leakage capacity of tritium.

[0049] Embodiment 2:

[0050] This embodiment 2 is further optimized on the basis of embodiment 1, such as Figure 1 and Figure 2 As shown, the specific setting methods of other supporting parts are provided.

[0051] In this embodiment, in order to serve as a pressure boundary and form a coolant channel, a pressure tube 3 is also included. The square box 5 and the spiral tube helium shield 4 are both located in the chamber of the pressure tube 3. The pressure tube 3 is provided with a cooling water inlet 12, and the cooling water inlet 12 is located above the spiral tube helium shield 4. The lower end of the square box 5 is connected to the bottom of the pressure tube 3, and the upper end of the square box 5 is connected to the cooling water outlet 13. In this scheme, the pressure tube 3 is a thick-walled cylindrical structure made of stainless steel material, which serves as a pressure boundary and accommodates cooling water with typical pressurized water reactor environmental parameters. In this way, the cooling water can flow in from the upper cooling water inlet 12, flow downward along the outer flow channel 7, thereby cooling the pressure tube 3 and the spiral tube helium shield 4, and then turn back upward at the bottom of the pressure tube 3 and the outer tube, so as to pass through the inner flow channel 8, flush and cool the sheet-like fuel element 6, and then flow out from the coolant outlet.

[0052] In order to completely separate the outer flow channel 7 from the inner flow channel 8, a shunt pipe 9 is further included. One end of the shunt pipe 9 is connected to the upper end of the square box 5 through an intermediate joint, and the other end of the shunt pipe 9 passes through the pressure pipe 3.

[0053] In order to reduce heat transfer, a protection tube 1 is also included. The pressure tube 3 and the protection tube 1 are coaxial and arranged in sequence from the inside to the outside. The chamber between the inner side of the protection tube 1 and the outer side of the pressure tube 3 is a nitrogen chamber 2. In this solution, the protection tube 1 is located outside the pressure tube 3 and is also a cylindrical structure; between the two is a nitrogen chamber 2, which is filled with nitrogen at normal pressure and is connected to a nitrogen inlet 10 and a nitrogen outlet 11 respectively.

[0054] In order to reduce the heat exchange between cooling water in different flow channels inside and outside the tube and provide a measurement lead channel, the shunt tube 9 and the square box 5 both adopt a first double-layer tube structure, and the gap in the first double-layer tube structure is filled with nitrogen.

[0055] In order to further prevent the tritium in the spiral tube helium shield 4 and the connected helium pipeline from penetrating and leaking into the cooling water, the spiral tube helium shield 4, the helium inlet pipe 18 and the helium outlet pipe 17 all adopt a second double-layer tube structure with a filling layer, and the second double-layer tube structure includes an inner tube, a sponge-like metal titanium tube filling layer and an outer tube from the inside to the outside; the inner tube and the outer tube are both made of stainless steel with a dense Al2O3 coating. In this solution, a helium pipeline with a double-layer stainless steel tube structure with an interlayer is adopted, and the double-layer tube is designed with Al2O3 coating. The inner tube contains tritium-containing helium, which can prevent the tritium in the helium shield and the connected helium pipeline from penetrating and leaking into the cooling water, thereby effectively reducing the radioactive hazards caused by tritium leakage.

[0056] In order to monitor the thermal neutron fluence rate near different sheet fuel elements 6 online, so as to accurately measure the relative power distribution of sheet fuel elements 6 at different positions during the power transient test, a measuring head of a self-powered neutron detector 16 is installed at the central area of ​​the wide side of each sheet fuel element 6, and the measuring heads of several self-powered neutron detectors 16 are located in the square box 5. In this scheme, the self-powered neutron detector 16 is preferably configured to be implanted in the hollow interlayer of the square box 5, and the number of detectors is consistent with the number of sheet fuel elements 6. Each detector corresponds to a layer of sheet fuel elements 6, and its installation position is close to the central area of ​​the wide side of the sheet fuel element 6. The self-powered neutron detector 16 arranged in the device can monitor the thermal neutron fluence rate near different sheet fuel elements 6 online; so as to accurately measure the relative power distribution of sheet fuel elements 6 at different positions during the power transient test.

[0057] In order to measure the temperature rise of the cooling water in the inner flow channel 8 in the fuel area, a plurality of fuel segment inlet thermocouples 14 are arranged below the bottommost sheet-shaped fuel element 6; and a plurality of fuel segment outlet thermocouples 15 are arranged above the topmost sheet-shaped fuel element 6. By measuring the temperature rise of the cooling water in the test fuel area of ​​the inner flow channel 8 and using the cooling water flow measured by the external system connected to the device, the total heat release power of all sheet-shaped fuel elements 6 can be obtained.

[0058] Embodiment 3:

[0059] This embodiment 3 is further limited on the basis of embodiment 2, and provides a specific working principle of a power transient irradiation device structure suitable for sheet elements and a power partition measurement method thereof.

[0060] Specific working principle:

[0061] The present invention provides a power transient irradiation device suitable for sheet elements. Figure 1 and Figure 2 As shown in the figure, the device is installed in the core area of ​​the research reactor and is part of the fuel power transient test system; the cooling water inlet and outlet, helium inlet and outlet pipes, and nitrogen inlet and outlet of the device are connected to the external equipment of the test system, and the external equipment provides cooling water and helium (high purity) that meet the test requirements. 3He gas) and nitrogen sources. From outside to inside, the main structural parts of the device include a protective tube 1, a pressure tube 3, a shunt tube 9 and a square box 5, as well as an air cavity or fluid domain separated by the above structure. The nitrogen cavity 2 between the protective tube 1 and the pressure tube 3 is mainly used for heat preservation, reducing the heat transfer from the pressure tube 3 to the protective tube 1; at the same time, the nitrogen inlet and outlet are connected to external equipment to realize the circulation and quality detection of nitrogen, thereby realizing the online detection of the integrity of the pressure tube 3 (whether there is cooling water leakage). The cooling water in the device is driven by an external device, and flows into the outer flow channel 7 after entering from the cooling water inlet 12, flows from top to bottom to the bottom of the square box 5, and then turns upward, flows into the inner flow channel 8 and is divided into two streams. After being cooled by the sheet-like fuel element 6 and heated, it converges at the top of the fuel section, and then flows out of the device from the cooling water outlet 13 through the shunt tube 9. As for the helium-3 gas, it is also driven by an external device to flow in from the helium inlet pipe 18, flows through a plurality of spiral tube helium screens 4 in sequence, enters the helium outlet pipe 17 through the connecting pipe, and finally flows out of the device.

[0062] A plurality of (usually 2 to 5) sheet fuel elements 6 are arranged vertically in a row and cooled by cooling water in the square box 5. The temperature rise of cooling water in the inner flow channel 8 measured by thermocouples arranged at the lower and upper parts of the fuel section, combined with the cooling water flow measured by an external system connected to the device, can be used to obtain the total heat release power of all sheet fuel elements 6. The relative power distribution of the sheet fuel elements 6 can be obtained by using the measurement data of the self-powered neutron detector 16 of each layer, and finally the real-time measurement of the power of each layer of sheet fuel elements 6 can be realized.

[0063] Each layer of sheet-like fuel element 6 corresponds to an independent helium screen, and the axial position and length of the helium screen are the same as those of the corresponding fuel element. The helium screen is a double-layer tube structure formed by spirally winding a helium gas pipeline around a square box 5. The diameter of the pipeline and the pitch of the spiral tube can be independently set for each layer of the spiral tube helium screen 4, so that different fuel element power variation ranges can be achieved at different axial positions.

[0064] The shunt pipe 9 and the square box 5 both adopt a hollow double-layer structure, and the gap of the double-layer structure is filled with nitrogen to reduce the heat exchange of cooling water between the inner and outer flow channels 7 and provide a measurement lead channel. Self-powered neutron detectors 16 are implanted in the hollow interlayer of the square box 5, and each detector corresponds to a layer of sheet fuel element 6, and its installation position is close to the central area of ​​the wide side of the sheet fuel element 6.

[0065] Power partition measurement method:

[0066] A plurality of thermocouples are respectively arranged at the lower and upper parts of the fuel section of the inner flow channel 8 to measure the temperature rise of the cooling water in the inner flow channel 8 in the test fuel area; the total heat release power of all the sheet-like fuel elements 6 can be obtained by measuring the cooling water flow rate measured by the external system connected to the device. On the other hand, the relative power distribution of the sheet-like fuel elements 6 measured online by the self-powered neutron detector 16 is combined with the total heat release rate power obtained by measuring the cooling water flow rate and the temperature rise, so that the power data of each sheet-like fuel element 6 during the fuel power transient test can be measured in real time.

[0067] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A power transient irradiation device suitable for sheet components, characterized in that: include: A square box (5), wherein the upper and lower ends of the square box (5) are both open, the inner cavity of the square box (5) is an inner flow channel (8) for cooling water to pass through, a plurality of sheet-shaped fuel elements (6) are uniformly spaced in sequence from bottom to top in the inner flow channel, and the plurality of sheet-shaped fuel elements (6) are placed vertically and are located on the same vertical plane; A plurality of spiral tube helium shields (4), wherein the plurality of spiral tube helium shields (4) correspond to the plurality of sheet-shaped fuel elements (6) one by one, and the spiral tube helium shields (4) are folded around the outside of the square box (5), and adjacent spiral tube helium shields (4) are connected to each other; the lower end of the spiral tube helium shield (4) at the bottom is connected to a helium inlet pipe (18), and the upper end of the spiral tube helium shield (4) at the top is connected to a helium outlet pipe (17); Both ends of the fuel section of the sheet-shaped fuel element (6) are located between the corresponding ends of the spiral tube helium shield (4).

2. The power transient irradiation device suitable for sheet components according to claim 1, characterized in that: It also includes a pressure tube (3), wherein the square box (5) and the spiral tube helium shield (4) are both located in the chamber of the pressure tube (3), and the pressure tube (3) is provided with a cooling water inlet (12), and the cooling water inlet (12) is located above the spiral tube helium shield (4); the lower end of the square box (5) is connected to the bottom of the pressure tube (3), and the upper end of the square box (5) is connected to the cooling water outlet (13).

3. The power transient irradiation device suitable for sheet components according to claim 2, characterized in that: It also comprises a shunt pipe (9), one end of which is connected to the upper end of the square box (5) via an intermediate joint, and the other end of which passes through the pressure pipe (3).

4. The power transient irradiation device suitable for sheet components according to claim 2, characterized in that: It also comprises a protection tube (1), the pressure tube (3) and the protection tube (1) being coaxial and arranged in sequence from the inside to the outside, and the chamber between the inside of the protection tube (1) and the outside of the pressure tube (3) being a nitrogen chamber (2).

5. The power transient irradiation device suitable for sheet components according to claim 4, characterized in that: The diverter tube (9) and the square box (5) both adopt a first double-layer tube structure, and the gap in the first double-layer tube structure is filled with nitrogen.

6. The power transient irradiation device suitable for sheet components according to claim 1, characterized in that: The spiral tube helium shield (4), the helium inlet tube (18) and the helium outlet tube (17) all adopt a second double-layer tube structure with a filling layer, and the second double-layer tube structure comprises, from inside to outside, an inner tube, a sponge-like titanium metal inter-tube filling layer and an outer tube.

7. The power transient irradiation device suitable for sheet components according to claim 6, characterized in that: The inner tube and the outer tube are both made of stainless steel material with a dense Al2O3 coating.

8. The power transient irradiation device suitable for sheet components according to claim 1, characterized in that: A measuring head of a self-powered neutron detector (16) is installed at the central area of ​​the wide side of each sheet-shaped fuel element (6), and the measuring heads of several self-powered neutron detectors (16) are located in the square box (5).

9. The power transient irradiation device suitable for sheet components according to claim 1, characterized in that: A plurality of fuel section inlet thermocouples (14) are arranged below the bottom sheet-shaped fuel element (6); and a plurality of fuel section outlet thermocouples (15) are arranged above the top sheet-shaped fuel element (6).

10. The power partition measurement method for a power transient irradiation device applicable to sheet components according to any one of claims 1 to 9, characterized in that: The following steps are involved: The inlet and outlet cooling water temperatures at the lower end and the upper end of the inner flow channel (8) are measured respectively to obtain the temperature rise of the cooling water in the test fuel area, and the cooling water flow rate is measured by an external system to obtain the total heat release power of all the sheet-shaped fuel elements (6); Obtaining the relative power distribution of each sheet-shaped fuel element (6) through online measurement; By means of the relative power distribution of each sheet-shaped fuel element (6) and combining it with the total heat release power, the power data of each sheet-shaped fuel element (6) during the fuel power transient test can be measured in real time.

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