Fuel element transient irradiation device

Abstract

The invention relates to the technical field of fuel element reactor irradiation tests, and provides a fuel element transient irradiation device which comprises a heat insulation pipe, a pressure pipe and a shunt pipe which are coaxially connected from outside to inside, the heat insulation pipe is communicated with a gas inlet pipe and a gas outlet pipe, the pressure pipe is communicated with a liquid inlet pipe, and the shunt pipe comprises an outer pipe and an inner pipe. The top of the inner pipe is communicated with a liquid outlet pipe, the lower portion of the inner pipe is communicated with a fuel element, a neutron absorption screen surrounds the fuel element, two end ports of the neutron absorption screen penetrate out of the side wall of the pressure pipe, a thermocouple is arranged between the outer pipe and the inner pipe, the measuring end of the thermocouple is arranged around the fuel element through a lead pipe, and the lead end of the thermocouple penetrates out of the shunt pipe. Through the multi-layer sleeve structure composed of the heat insulation pipe, the pressure pipe and the shunt pipe and the reasonable layout of the gas inlet pipe, the gas outlet pipe, the liquid inlet pipe, the liquid outlet pipe and the neutron absorption screen, the transient irradiation test requirement of the fuel element is met, the complexity of the structure is reduced, and the integration level of the structure is improved.

Description

Technical Field

[0001] The invention relates to the technical field of fuel element irradiation testing, and in particular to a fuel element transient irradiation device. Background Art

[0002] Fuel element irradiation test is a key link in the design and development of new fuel elements. It can be divided into steady-state irradiation test and transient irradiation test according to the power level of the fuel element. Among them, transient irradiation test refers to irradiation test that can achieve rapid changes in fuel element power. The core of transient irradiation test is to quickly adjust and control the power of fuel elements. Nuclear technology advanced countries started early in the research of transient irradiation test technology and developed a variety of technical methods, including adjusting reactor power, displacement of irradiation device, mechanical movement of absorber, and helium-3 gas loop.

[0003] In comparison, the helium-3 gas loop method is a more advanced technology that uses helium-3 gas as a neutron absorber and adjusts the density of helium-3 gas to change the neutron injection in the area around the fuel element, thereby achieving fuel element power regulation.

[0004] Compared with the steady-state irradiation test device, the transient irradiation test device needs to add an additional helium-3 gas neutron absorption screen. At the same time, since helium-3 gas generates heat when absorbing neutrons, it is also necessary to design a matching cooling water flow channel for the helium-3 gas neutron absorption screen. This significantly increases the structural complexity of the transient irradiation device, thereby increasing the manufacturing cost and the difficulty of the test operation. Summary of the invention

[0005] The object of the present invention is to provide a fuel element transient irradiation device to solve the above-mentioned technical problems, meet the requirements of fuel element transient irradiation test, reduce the complexity of the structure, and improve the integration of the structure.

[0006] The present invention is achieved through the following technical scheme: a fuel element transient irradiation device, comprising an insulation tube, a pressure tube and a shunt tube coaxially connected from outside to inside, the insulation tube is respectively connected with an air inlet pipe and an air outlet pipe, the pressure tube is connected with a liquid inlet pipe, the shunt tube comprises an outer tube and an inner tube, the top of the inner tube is connected with a liquid outlet pipe, the bottom of the inner tube is connected with a fuel element, the fuel element is surrounded by a neutron absorption screen, both end ports of the neutron absorption screen are passed through the side wall of the pressure tube, a thermocouple is arranged between the outer tube and the inner tube, the thermocouple measuring end is arranged around the fuel element through a lead tube, and the thermocouple lead end passes through the outside of the shunt tube.

[0007] Furthermore, a plurality of inner gaskets are evenly arranged between the outer tube and the inner tube, and a plurality of outer gaskets are evenly arranged between the outer tube and the pressure tube.

[0008] Furthermore, the thermal insulation pipe comprises a first flange and a second flange for sealingly connecting with the top cover of the research reactor, and the air inlet pipe and the air outlet pipe both pass through between the first flange and the second flange.

[0009] Preferably, the pressure pipe comprises a third flange and a fourth flange for sealingly connecting with the second flange, and both end ports of the neutron absorption screen pass through between the third flange and the fourth flange.

[0010] Preferably, the shunt pipe comprises a top cover sealedly connected to the third flange, and both the inner pipe and the outer pipe are sealedly connected to the top cover.

[0011] Furthermore, the neutron absorption screen is a double helix structure formed by bending a single tube.

[0012] Further, the air inlet pipe extends to the bottom of the insulation pipe.

[0013] Furthermore, nitrogen is filled between the insulation tube and the pressure tube, and a coolant is introduced into the pressure tube.

[0014] The present invention has at least the following advantages and beneficial effects:

[0015] (1) The multi-layer casing structure composed of the insulation tube, pressure tube and shunt tube, as well as the reasonable layout of the air inlet pipe, air outlet pipe, liquid inlet pipe, liquid outlet pipe and neutron absorption screen, has a compact and reliable structure, occupies a small space, is easy to manufacture and test, meets the requirements of the transient irradiation test of fuel elements, and ensures the accuracy and safety of the test;

[0016] (2) By arranging the neutron absorption screen inside the pressure tube, and passing the coolant into the pressure tube through the liquid inlet pipe, and then flowing out from the liquid outlet pipe after passing through the fuel element and the inner tube, a coolant flow channel is formed in the pressure tube, so that the coolant can be used to cool the neutron absorption screen while extracting the heat from the fuel element, thereby reducing the complexity of the structure and improving the integration of the structure;

[0017] (3) By setting an inner pad between the outer tube and the inner tube, and setting an outer pad between the outer tube and the pressure tube, the inner tube, the outer tube and the pressure tube are kept coaxial, which effectively reduces vibration transmission and ensures the stability of the internal environment of the pressure tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0019] Figure 1A schematic structural diagram of a fuel element transient irradiation device provided by the present invention;

[0020] Figure 2 For the present invention Figure 1 Sectional view along AA direction;

[0021] Figure 3 For the present invention Figure 2 Cross-sectional view along the BB direction;

[0022] Figure 4 For the present invention Figure 3 Sectional view along CC direction;

[0023] Figure 5 For the present invention Figure 3 Cross-sectional view along the DD direction;

[0024] Figure 6 A schematic diagram of the structure of an insulation tube in a fuel element transient irradiation device provided by the present invention;

[0025] Figure 7 A schematic structural diagram of a pressure tube in a fuel element transient irradiation device provided by the present invention;

[0026] Figure 8 A schematic diagram of the structure of a shunt tube in a fuel element transient irradiation device provided by the present invention;

[0027] Fig. 9 A schematic diagram of the structure of a neutron absorption screen in a fuel element transient irradiation device provided by the present invention;

[0028] Icons: 1-insulating pipe, 11-inlet pipe, 12-outlet pipe, 13-first flange, 14-second flange, 2-pressure pipe, 21-liquid inlet pipe, 22-third flange, 23-fourth flange, 3-diverter pipe, 31-outer pipe, 32-inner pipe, 33-liquid outlet pipe, 34-inner pad, 35-outer pad, 36-top cover, 4-fuel element, 5-neutron absorption screen, 6-thermocouple. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example

[0032] like Figure 1-9 As shown, in this embodiment, a fuel element transient irradiation device is mainly disclosed, which has a simple and reliable structure and is easy to manufacture and test. Its main structure includes an insulation tube 1, a pressure tube 2 and a shunt tube 3 which are coaxially connected from outside to inside. The insulation tube 1 is respectively connected with an air inlet tube 11 and an air outlet tube 12, the pressure tube 2 is connected with a liquid inlet tube 21, the shunt tube 3 includes an outer tube 31 and an inner tube 32, the top of the inner tube 32 is connected with a liquid outlet tube 33, and the lower part of the inner tube 32 is connected with a fuel element 4, the fuel element 4 is surrounded by a neutron absorption screen 5, and both end ports of the neutron absorption screen 5 are passed through the side wall of the pressure tube 2, a thermocouple 6 is arranged between the outer tube 31 and the inner tube 32, the measuring end of the thermocouple 6 is arranged around the fuel element 4 through a lead tube, and the lead end of the thermocouple 6 passes through the outside of the shunt tube 3;

[0033] Specifically, the insulation pipe 1, the pressure pipe 2 and the diversion pipe 3 form a multi-layer casing structure, and the insulation pipe 1 and the pressure pipe 2 both adopt a round pipe structure with a spherical head at one end and an open end at the other end;

[0034] The space between the insulation tube 1 and the pressure tube 2 is filled with nitrogen as an insulation layer to reduce the heat conduction between the irradiation device and the research reactor. In addition, the insulation tube 1 and the pressure tube 2 can be monitored for leakage based on the changes in the temperature, humidity, pressure and other parameters of the nitrogen filled.

[0035] A coolant is introduced into the pressure tube 2. The coolant may be cooling water. The coolant enters the pressure tube 2 through the liquid inlet pipe 21, then enters the inner tube 32 after passing through the fuel element 4, and finally flows out of the irradiation device from the liquid outlet pipe 33 and returns to the coolant loop outside the pile, so that the coolant is circulated, so that the coolant can be used to cool the neutron absorption screen 5 while extracting the heat of the fuel element 4;

[0036] The neutron absorption screen 5 can be a helium-3 screen, and helium-3 gas is introduced into its pipeline as a neutron absorber. The ports at both ends of the neutron absorption screen 5 serve as the inlet and outlet of the helium-3 gas respectively. The neutron injection in the area around the fuel element 4 is changed by adjusting the density of the helium-3 gas, thereby realizing the adjustment of the power of the fuel element 4.

[0037] The thermocouple 6 can adopt existing technology, and multiple thermocouples 6 are evenly distributed along the circumferential direction in the gap between the outer tube 31 and the inner tube 32. The lead wire of the thermocouple 6 passes through the lead tube so that the measuring point at the end of the thermocouple 6 is placed around the fuel element 4 to measure the temperature of the fuel element 4.

[0038] Furthermore, in the specific implementation, Figure 4 , 8 As shown, a plurality of inner pads 34 are evenly arranged between the outer tube 31 and the inner tube 32 provided in the embodiment of the present invention, for fixing the relative position of the outer tube 31 and the inner tube 32, so that the gap between the outer tube 31 and the inner tube 32 is uniform and remains coaxial, and a plurality of outer pads 35 are evenly arranged between the outer tube 31 and the pressure tube 2, for fixing the relative position of the outer tube 31 and the pressure tube 2, so that the coolant can be evenly distributed between the outer tube 31 and the pressure tube 2, and the outer tube 31 and the pressure tube 2 are kept coaxial, so that the inner tube, the outer tube and the pressure tube are kept coaxial, thereby effectively reducing vibration transmission and ensuring the stability of the internal environment of the pressure tube.

[0039] Furthermore, in the specific implementation, Figure 2 , 3 As shown in FIG. 6 , the above-mentioned thermal insulation pipe 1 provided in the embodiment of the present invention comprises a first flange 13 and a second flange 14 for sealingly connecting with the research reactor cover, and the air inlet pipe 11 and the air outlet pipe 12 both pass through between the first flange 13 and the second flange 14; Figure 7 As shown, the pressure pipe 2 includes a third flange 22 and a fourth flange 23 for sealingly connecting with the second flange 14, and both end ports of the neutron absorption screen 5 pass through between the third flange 22 and the fourth flange 23; specifically, an oblique boss structure is provided on the connecting section between the first flange 13 and the second flange 14 and between the third flange 22 and the fourth flange 23, and a through hole is obliquely opened on the end surface of the oblique boss structure for the ports of the air inlet pipe 11, the air outlet pipe 12 or the neutron absorption screen 5 to pass through obliquely, so that the fluid in the channel forms a more uniform flow velocity distribution, reduces local turbulence, and thus improves the transmission efficiency;

[0040] It should be noted that the exit position of the neutron absorption screen 5 should avoid interference with the entry position of the liquid inlet pipe 21; in addition, the air inlet pipe 11, the air outlet pipe 12 and the port of the neutron absorption screen 5 extending out of the irradiation device should not be too long to ensure smooth assembly;

[0041] like Figure 8As shown, the shunt pipe 3 includes a top cover 36 sealed with the third flange 22, and the inner tube 32 and the outer tube 31 are both sealed with the top cover 36. It should be noted that the gap between the outer tube 31 and the inner tube 32 cannot constitute a circulation channel for the coolant due to the obstruction of the top cover 36, so that the coolant between the outer tube 31 and the inner tube 32 is in a relatively static state, thereby avoiding the erosion and wear of the lead wire of the thermocouple 6 by the coolant, and extending the service life of the thermocouple 6; in addition, the liquid outlet pipe 33 can be integrally formed with the top cover 36, and the liquid outlet pipe 33 is vertically arranged at the center position of the top cover 36, and a connecting flange is arranged at the end of the liquid outlet pipe 33, so as to facilitate external connection to the interface flange of the off-stack coolant circuit by bolts.

[0042] Furthermore, in the specific implementation, Fig. 9 As shown, the neutron absorption screen 5 provided in the embodiment of the present invention is a double helix structure formed by bending a single tube; specifically, the folded portion of the single tube is U-shaped, and the folded single tubes are wound together in the same direction to form a double helix structure, which has a simple structure and occupies a small space, can effectively reduce the volume of the irradiation device, and is easy to process, which can reduce the manufacturing cost of the irradiation device.

[0043] Furthermore, in the specific implementation, Figure 2 , 6 As shown, the above-mentioned air inlet pipe 11 provided in the embodiment of the present invention extends to the bottom of the insulating pipe 1; it can prevent the gas from being retained in the insulating pipe 1, help to ensure the continuous flow of gas, reduce dead zones, and improve the gas flow efficiency of the insulation layer between the insulating pipe 1 and the pressure pipe 2.

[0044] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fuel element transient irradiation device, characterized in that: The invention comprises an insulating tube (1), a pressure tube (2) and a shunt tube (3) which are coaxially connected from outside to inside. The insulating tube (1) is respectively connected to an air inlet tube (11) and an air outlet tube (12). The pressure tube (2) is connected to a liquid inlet tube (21). The shunt tube (3) comprises an outer tube (31) and an inner tube (32). The top of the inner tube (32) is connected to a liquid outlet tube (33). A fuel element (4) is arranged below the inner tube (32). A neutron absorption screen (5) surrounds the fuel element (4). Both end ports of the neutron absorption screen (5) pass through the side wall of the pressure tube (2). A thermocouple (6) is arranged between the outer tube (31) and the inner tube (32). The measuring end of the thermocouple (6) is arranged around the fuel element (4) through a lead tube. The lead end of the thermocouple (6) passes through the outside of the shunt tube (3).

2. A fuel element transient irradiation device as claimed in claim 1, characterized in that: A plurality of inner pads (34) are evenly arranged between the outer tube (31) and the inner tube (32), and a plurality of outer pads (35) are evenly arranged between the outer tube (31) and the pressure tube (2).

3. A fuel element transient irradiation device as claimed in claim 1, characterized in that: The thermal insulation pipe (1) comprises a first flange (13) and a second flange (14) for sealingly connecting to a research reactor cover, and the air inlet pipe (11) and the air outlet pipe (12) both pass through between the first flange (13) and the second flange (14).

4. A fuel element transient irradiation device as claimed in claim 3, characterized in that: The pressure pipe (2) comprises a third flange (22) and a fourth flange (23) for sealingly connecting with the second flange (14), and both end ports of the neutron absorption screen (5) pass through between the third flange (22) and the fourth flange (23).

5. A fuel element transient irradiation device as claimed in claim 4, characterized in that: The diverter pipe (3) comprises a top cover (36) which is sealed to the third flange (22); the inner pipe (32) and the outer pipe (31) are both sealed to the top cover (36).

6. A fuel element transient irradiation device as claimed in claim 1, characterized in that: The neutron absorption screen (5) is a double helix structure formed by bending a single tube.

7. A fuel element transient irradiation device as claimed in claim 1, characterized in that: The air inlet pipe (11) extends to the bottom of the thermal insulation pipe (1).

8. A fuel element transient irradiation device as claimed in claim 1, characterized in that: The space between the thermal insulation tube (1) and the pressure tube (2) is filled with nitrogen, and a coolant is introduced into the pressure tube (2).

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