Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor

Abstract

A fuel fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor, comprising a box body, a spiral screen channel, a fuel ball inlet, a fuel ball outlet, and a waste outlet; the box body is arranged on the inlet line of the baffle, with the fuel ball inlet provided on the top of the box body and the fuel ball outlet and the waste outlet provided on the bottom; inside the box body, between the fuel ball inlet and the fuel ball outlet, the spiral screen channel is provided, and the spiral screen channel has a certain angle and is in an inclined state, with the waste outlet being located below the spiral screen channel.During the operation of the present application, when the fuel balls, fuel ball fragment, and the dust mixture pass through the device, the device can completely separate the intact fuel balls from the fuel ball fragment and the graphite dust from the graphite ball fragment, thus effectively preventing the fragment and dust from entering the baffle and affecting its normal operation, thereby improving the normal operation of the fuel loading and unloading system and increasing the reliability of the system operation.

Description

Cross-references to related applications

[0001] This application claims priority to the Chinese patent application filed with the Chinese Patent Office on February 21, 2023, with Application No. 202310147568.5 and invention titled “Fuel assembly fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor,” the entire contents of which are hereby incorporated by reference. Technical area

[0002] The present application belongs to the technical field of screening devices and relates in particular to a fuel element fragment screening device of a loading and unloading system for nuclear fuel in a gas-cooled high-temperature reactor. Background technology

[0003] Gas-cooled high-temperature reactors are a fourth-generation nuclear power generation system whose design concept is based on the fact that their inherent physical safety features—such as no core meltdown, no large-scale release of radioactive materials, and no need for off-site emergency measures under extreme accident conditions—offer unique development advantages and open up broad development prospects in the context of energy scarcity and CO2 reduction targets. However, the fourth-generation gas-cooled high-temperature reactor is a brand-new system, and experience is lacking for much of its design and operation. The system must be continuously reviewed and improved during testing and operation in the model project.During the design of the baffle of the nuclear fuel loading and unloading system, the influence of fuel fragments and graphite dust on the function of the baffle was not taken into account, which led to shearing of the fuel sphere during operation and thus to the bursting of the fuel sphere, so that the UO2 in the fuel sphere entered the primary circuit, thereby increasing the radiation dose of the dust in the primary circuit and generating a large amount of nuclear waste with a high radiation dose, which in turn resulted in unnecessary fuel loss and high costs for nuclear waste disposal.However, when the system operates normally in a high-temperature environment, the disturbances of the primary circuit medium as well as the deposits and dust generated by the friction during the fuel sphere filling process will enter the baffle along the sphere unloading tube, causing shearing of the fuel sphere and severe damage to the fuel spheres, making the normal operation of the fuel loading and unloading system impossible and seriously limiting the hot test process of the high-temperature reactor. Content of the invention

[0004] The purpose of the present application is to provide a fuel fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor to solve the problem of shearing of the fuel element ball by the baffle during the operation of the fuel loading and unloading system and to improve the reliability of the loading and unloading system.

[0005] To achieve the above objectives, this application uses the following technical solutions: A fuel fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor, comprising a box body, a spiral screen channel, a fuel ball inlet, a fuel ball outlet, and a waste outlet; the box body is arranged on the inlet line of the baffle, with the fuel ball inlet provided on the top of the box body and the fuel ball outlet and the waste outlet provided on the bottom; inside the box body, between the fuel ball inlet and the fuel ball outlet, the spiral screen channel is provided, and the spiral screen channel has a certain angle and is in an inclined state, with the waste outlet being located below the spiral screen channel.

[0006] In addition, the inclination angle of the spiral screen channel is 45° to 80°, and the distance between the inlet and outlet of the spiral screen channel projected perpendicularly onto a plane is at least three times the fuel sphere diameter; the diameter of the planar projection of the ring of the spiral screen channel is 5 mm smaller than the diameter of the fuel spheres, and the straight line between any two rings of the spiral screen channel is 85% of the diameter of the fuel spheres.

[0007] In addition, a uniform spiral sieve interval is arranged on the spiral sieve channel and the sieve interval is designed to sieve fuel balls and graphite dust with a diameter of less than 80% of the nominal value. there is a guide funnel opening at the top of the fuel element sphere outlet and the outlet of the spiral screen channel is connected to the guide funnel opening.

[0008] In addition, an electromagnetic throttle switch is also provided at the fuel ball outlet of the spiral sieve channel.

[0009] In addition, a buffer hopper and a fuel sphere fragment buffer tank are arranged above the waste outlet; the buffer hopper is connected to the top of the fuel sphere fragment buffer tank, and the waste outlet is connected to the bottom of the fuel sphere fragment buffer tank.

[0010] In addition, an isolation valve is provided at the junction between the buffer funnel and the nuclear fuel sphere fragment buffer tank. The isolation valve comprises two superimposed round steel plates, each of which has an 8-shaped hole in the center. The steel plates are connected to a drive device. When the two holes between the two steel plates overlap, the flow opening is opened, and when they are staggered, the flow opening is sealed and closed.

[0011] In addition, an outlet valve is provided at the connection point between the waste outlet and the nuclear fuel sphere fragment buffer tank, the structure of the outlet valve being the same as that of the isolation valve.

[0012] Furthermore, a level measuring element, a pressure measuring element, and a connecting line are provided on the nuclear fuel sphere fragment buffer tank, with a vacuum valve being provided on the connecting line; a piping is provided between the waste outlet and the fuel sphere outlet, with first and second valves being arranged on the piping.

[0013] In addition, an inspection opening is provided on the box body.

[0014] Compared to the prior art, the present application has the following technical effects: The present application provides a fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor, and during operation of the device, when the fuel balls, fuel ball fragment, and the dust mixture pass through the device, the device can completely separate the intact fuel balls from the fuel ball fragment and the graphite dust from the graphite ball fragment, thus effectively preventing the fragment and dust from entering the baffle and affecting its normal operation, thereby increasing the reliability of the fuel loading and unloading system. Figures Fig. 1 shows a schematic representation of the structure of the screening device of the present application. Fig. 2 shows a plan view of the structure of the isolation valve of the present application. Fig. Figure 3 shows a connection diagram between the device and the system. Fig. Figure 4 shows a schematic representation of the baffle. Specific embodiments

[0015] In the following, the technical solution of the present application will be described clearly and completely in conjunction with the figures. It is understood that the description of the embodiments represents only a portion of the embodiments of the present application and not all embodiments. Based on the embodiments in the present application, all other embodiments that are readily apparent to the general technical personnel without creative effort fall within the scope of this application.

[0016] In describing the present application, it should be understood that azimuth or positional relationships referring to the terms "center," "top," "bottom," "left," "right," "vertical," "horizontal," "inside," "outside," etc., have the azimuth or positional relationships based on the figures. They are intended to facilitate and simplify the description of the present application, rather than to indicate or imply that the stated device or component must have a particular orientation, be constructed, and operate in a particular orientation. Therefore, they should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be interpreted as indicating or implying relative importance.

[0017] It should be noted that in the description of the present application, the terms "installing", "connecting" and "connecting" are to be understood in a broad sense unless expressly stated or limited otherwise, e.g., it may be a fixed connection, a detachable connection, or a one-piece connection; it may be a mechanical connection or an electrical connection; it may be a direct connection, an indirect connection via an intermediate medium, or a connection within the two elements. For general technical personnel in the field, the specific meaning of the above terms in the present application may be understood depending on the specific circumstances.

[0018] With reference to Fig. 1 to Fig. 4 shows the Fig. 1 shows a fuel fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor. The fuel fragment screening device is installed on the inlet line of the baffle of the nuclear fuel loading and unloading system and is connected in series with the baffle on the same line. During normal operation of the system, the fuel pellets, fuel pellet fragments, and graphite dust first enter the fragment screening device before entering the baffle. The screening device separates the intact fuel pellets from the fuel pellet fragments and graphite dust to ensure that neither fuel pellet fragments nor graphite dust enter the baffle.

[0019] As in Fig. 1, the inlet line of the baffle of the nuclear fuel loading and unloading system is cut off and a box body 003 with a volume of more than 0.3 cm3installed on the severed part of the line, the box body 003 being provided with a fuel ball inlet 001, a fuel ball outlet 006 and a waste outlet 013.A spiral sieve channel 004 is provided between the fuel ball inlet 001 and the fuel ball outlet 006, one end of the spiral sieve channel being connected to the fuel ball inlet 001 and the other end to the fuel ball outlet 006, whereby a sieve channel is formed in the box 003, the angle of inclination of the spiral sieve channel 004 being 45° to 80° and the straight line of the distance between the inlet and outlet of the spiral sieve channel 004 projected perpendicularly onto a plane being at least three times the fuel ball diameter; the diameter of the planar projection of the ring of the spiral sieve channel 004 being 5 mm smaller than the diameter of the fuel balls and the straight line between any two rings of the spiral sieve channel 004 being 85% of the diameter of the fuel balls.The designed pressure load capacity of box body 003 is over 9 MPa and an inspection port 022 is provided on the box body to facilitate inspection of the situation inside the box body during maintenance.

[0020] During normal operation of the device, the fuel balls 002, their fragments, and the graphite dust 020 generated by flow wear in the reactor core pass from the fuel ball inlet 001 into the spiral screen channel 004. In the spiral screen channel 004, the fuel balls 002, their fragments, and the graphite dust 020 generated by flow wear in the reactor core are mixed and separated into two paths after passing through the spiral screen channel 004. One path is designed to allow undamaged fuel balls or fuel balls that are not seriously damaged and do not cause other fuel balls to be cut after entering the baffle, and then to pass through the guide funnel opening 005 into the fuel ball outlet 006, and then pass through the fuel ball outlet 006 into the baffle.In order to prevent the fuel ball 002 from shattering after reaching the fuel ball outlet 006 and affecting the normal function of the baffle, an electromagnetic throttle switch 007 is provided at the fuel ball outlet 006. When the orifice plate malfunctions, the electromagnetic throttle switch blocks the fuel ball 002. After the baffle operates twice, the electromagnetic throttle switch stops its function and releases the fuel ball 002 to ensure the normal function of the baffle.

[0021] The other route for sorted fuel is designed for the fuel ball fragments and graphite dust 020 with a diameter of less than 80% of the nominal value to fall into the buffer hopper 021 after sorting through the screen channel 004, to reach the nuclear fuel ball fragments buffer tank 010 for buffering via the isolation valve 008, then to reach the waste outlet line 013 via the outlet valve 011 and finally to be discharged into the line of the spent fuel storage system.

[0022] An isolation valve 008 is provided at the lower part of the buffer funnel 021. The isolation valve 008 is connected to the buffer container 021 at the top and to the nuclear fuel sphere fragment buffer tank 010 at the bottom. After opening the isolation valve 008, the separated fuel element fragment and the graphite dust 020 can fall into the buffer funnel 021 for interim storage.

[0023] The isolation valve 008 consists of two round steel plates arranged one above the other, each of which has an 8-shaped hole in the middle; as in Fig. As shown in Figure 2, a drive wheel is provided on the edge of the upper steel plate, which is driven by a pneumatic or electric actuator 009 for opening and closing. The upper steel plate is capable of rotating 90 degrees in both directions. When the two holes between the steel plates overlap, the passage opens, allowing nuclear waste and graphite dust to flow directly from the buffer hopper 021 into the nuclear fuel sphere fragments buffer tank 010. When the two holes between the two steel plates do not overlap, the passage is closed, preventing nuclear waste and graphite dust from flowing directly from the buffer hopper 021 into the nuclear fuel sphere fragments buffer tank 010.

[0024] The upper part of the nuclear fuel sphere fragment buffer tank 010 is connected to the isolation valve 008, and the lower part is connected to the exhaust valve 011. To detect the material level of the nuclear fuel sphere fragment buffer tank 010 during normal operation, a level measuring element 019 is provided at its upper end. When the material level rises and the level measuring element 019 reaches a certain height, the system executes the discharge program to discharge the nuclear fuel sphere fragment in the nuclear fuel sphere fragment buffer tank 010 and the graphite dust 020 into the waste outlet line 013.

[0025] An outlet valve 011 is mounted beneath the fuel sphere-fragmentation buffer tank 010. The upper part is connected to the fuel sphere-fragmentation buffer tank 010, and the lower part is connected to the spent fuel discharge line. Its structure is the same as that of the isolation valve 008 and consists of two round steel plates, each with an 8-shaped opening in the center, as shown in Fig.As shown in Figure 2, a drive wheel is provided on the edge of the upper steel plate, which is driven by a pneumatic or electric actuator 009 for opening and closing. The upper steel plate is capable of rotating 90 degrees in both directions. When the two holes between the steel plates overlap, the passage opens, allowing nuclear waste and graphite dust from the nuclear fuel sphere fragment buffer tank 010 to directly enter the waste outlet pipe 013. When the two holes between the two steel plates do not overlap, the passage is closed, preventing nuclear waste and graphite dust from the nuclear fuel sphere fragment buffer tank 010 from directly entering the waste outlet pipe 013.

[0026] Under normal operating conditions, the pressure in the screening device 003 is always above 7-9 MPa. In order to avoid accidents, the supply and discharge control of the nuclear fuel sphere fragments buffer tank 010 must be carried out as follows: before the isolation valve 008 is opened to discharge into the nuclear fuel sphere fragments buffer tank 010, the outlet valve 011 must be closed, the second valve 017 between the nuclear fuel sphere fragments buffer tank 010 and the waste outlet pipe 013 must be closed, the first valve 015 between the nuclear fuel sphere fragments buffer tank 010 and the fuel sphere outlet pipe 006 must be closed, the vacuum valve 023 of the nuclear fuel sphere fragments buffer tank 010 must be closed, the first valve 015 must be open, and the isolation valve 008 must be opened when the pressure rise of the pressure sensing element 024 is in balance with the system pressure.Under normal operating conditions, the isolation valve 008 remains open. When the material level signal 019 is output, the isolation valve 008 is closed and the drain process is performed.

[0027] When the supply of the nuclear fuel sphere fragment buffer tank 010 is completed, the system performs the discharge process, that is, the isolation valve 008 is closed, the second valve 017 between the nuclear fuel sphere fragment buffer tank 010 and the waste outlet line 013 is closed, the first valve 015 between the nuclear fuel sphere fragment buffer tank 010 and the fuel sphere outlet line 006 is closed, the vacuum valve 023 of the nuclear fuel sphere fragment buffer tank 010 is opened, and when the pressure drop of the pressure sensing element 024 is balanced with the pressure of the waste outlet line 013, the vacuum valve 023 is closed, the isolation valve 011 is opened to discharge the fragment and graphite dust 020 into the spent fuel waste outlet line 013 and then transported to the spent fuel storage tank.

[0028] In order to ensure material supply and discharge in the event of a failure of the vacuum valve 023, when the vacuum valve fails and suction cannot be performed, the outlet valve 011 is closed before opening the isolation valve 008 for supply, the second valve 017 between the nuclear fuel sphere fragment buffer tank 010 and the waste discharge line 013 is closed, the first valve 015 between the nuclear fuel sphere fragment buffer tank 010 and the fuel sphere outlet line 006 is closed, the vacuum valve 023 of the nuclear fuel sphere fragment buffer tank 010 is closed, the first valve 015 and the isolation valve 008 are opened when the pressure rise of the pressure sensing element 024 is in balance with the system pressure, and the fragment and graphite dust 020 are discharged into the nuclear fuel sphere fragment buffer tank 010.

[0029] When the vacuum valve 023 cannot exhaust and the nuclear fuel sphere fragments buffer tank 010 needs to be discharged, the isolation valve 008 is closed, the second valve 017 between the nuclear fuel sphere fragments buffer tank 010 and the waste discharge line 013 is closed, the first valve 015 between the nuclear fuel sphere fragments buffer tank 010 and the fuel sphere outlet line 006 is closed, the vacuum valve 023 of the nuclear fuel sphere fragments buffer tank 010 is closed, the second valve 017 is opened, and when the pressure drop of the pressure sensing element 024 is balanced with the pressure of the waste discharge line 013, the isolation valve 011 is opened to discharge the fragments and graphite dust 020 into the spent fuel waste outlet line 013 and then transported to the spent fuel storage tank.

[0030] Finally, it should be noted that the above embodiments merely serve to illustrate the technical solutions of the present application and do not limit them. Although the present application has been described in detail using the above embodiments, it is possible for those skilled in the art to modify the technical solutions described in the above embodiments or to replace some or all of the technical features with equivalent ones; however, these modifications or replacements do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 202310147568.5

[0001]

Claims

[1] Fuel element fragment screening device of a loading and unloading system for nuclear fuel in a gas-cooled high-temperature reactor, characterized by that it comprises a box body (003), a spiral screen channel (004), a fuel ball inlet (001), a fuel ball outlet (006), and a waste outlet (013); that the box body (003) is arranged on the inlet line of the baffle, wherein the fuel ball inlet (001) is provided on the top side of the box body (003), and the fuel ball outlet (006) and the waste outlet (013) are provided on the bottom side; that the spiral screen channel (004) is provided inside the box body (003), between the fuel ball inlet (001) and the fuel ball outlet (006), and the spiral screen channel (004) has a certain angle and is in an inclined state, wherein the waste outlet (013) is located below the spiral screen channel (004). [2] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 1, characterized by that the angle of inclination of the spiral sieve channel (004) is 45° to 80° and the straight line of the distance between the inlet and outlet of the spiral sieve channel (004) projected perpendicularly onto a plane is at least three times the fuel ball diameter; that the diameter of the planar projection of the ring of the spiral sieve channel (004) is 5 mm smaller than the diameter of the fuel balls and the straight line between any two rings of the spiral sieve channel (004) is 85% of the diameter of the fuel balls. [3] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 1, characterized bythat a uniform spiral sieve interval is arranged on the spiral sieve channel (004) and the sieve interval is designed to sieve fuel balls and graphite dust with a diameter of less than 80% of the nominal value. [4] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 1, characterized by that a guide funnel opening (005) is located at the top of the fuel element ball outlet (006) and the outlet of the spiral sieve channel (004) is connected to the guide funnel opening (005). [5] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 4, characterized by that an electromagnetic throttle switch (007) is also provided at the fuel ball outlet (006) of the spiral sieve channel (004). [6] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 1, characterized by that a buffer funnel (021) and a nuclear fuel sphere fragment buffer tank (010) are arranged above the waste outlet (013); that the buffer funnel (021) is connected to the top of the nuclear fuel sphere fragment buffer tank (010) and the waste outlet (013) is connected to the bottom of the nuclear fuel sphere fragment buffer tank (010). [7] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 6, characterized bythat an isolation valve (008) is provided at the connection point between the buffer funnel (021) and the nuclear fuel sphere fragment buffer tank (010), wherein the isolation valve (008) comprises two superimposed round steel plates, each of which has an 8-shaped hole in the center; that the steel plates are connected to a drive device, wherein when the two holes between the two steel plates overlap, the flow opening is opened, and when they are arranged offset, the flow opening is sealed and closed. [8] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 7, characterized bythat an outlet valve (011) is provided at the connection point between the waste outlet (013) and the nuclear fuel ball fragment buffer tank (010), the structure of the outlet valve (011) being the same as that of the isolation valve (008). [9] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 8, characterized by that a level measuring element (19), a pressure measuring element (024) and a connecting line are provided on the nuclear fuel sphere fragment buffer tank (010), wherein a vacuum valve (023) is provided on the connecting line; that a vacuum connecting line is provided between the waste outlet (013) and the fuel sphere outlet (006), wherein manual isolation valves (014, 015) and pneumatic isolation valves (017, 018) are attached to the connecting line. [10] Fuel element fragment screening device of a nuclear fuel loading and unloading system in a gas-cooled high-temperature reactor according to claim 1, characterized by that an inspection opening (022) is provided on the box body (003).

Images