Neutron extraction device for fast neutron reactor

Abstract

The embodiment of the present invention discloses a neutron extraction device for a fast neutron reactor, comprising: a body, the body is arranged in the fast neutron reactor coolant, and is used to discharge the coolant; wherein the body is provided with a cavity, and the neutrons are led out of the fast neutron reactor through the cavity; and a shielding layer, the shielding layer is arranged outside the body, and is used to prevent the neutrons from leaking. This neutron extraction device helps to lead the neutrons in the reactor to the detector located outside the reactor main container, thereby realizing online monitoring.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of reactor technology, and in particular to a neutron extraction device for a fast neutron reactor. Background Art

[0002] The nuclear measurement system is an important part of the control and protection system of a nuclear power plant. It is used to measure the reactor power and its changes, power distribution, power change rate, etc.

[0003] The current measurement system layout scheme can place the detector inside the reactor main vessel, or outside the reactor main vessel, that is, out-of-core measurement.

[0004] When measuring outside the reactor, since most existing fast neutron reactors are pool-type cores with large main vessels, the detectors are placed outside the main vessels and are far away from the core. In addition, existing fast neutron reactors use liquid metal sodium as a coolant, and the shielding effect of sodium on neutrons will reduce the level of neutron injection rate at the detector position. Summary of the invention

[0005] In view of the above problems, the present invention is proposed to provide a neutron extraction device for a fast neutron reactor that overcomes the above problems or at least partially solves the above problems.

[0006] The present invention provides a neutron extraction device for a fast neutron reactor, comprising: a body, which is arranged in the coolant of the fast neutron reactor and is used to discharge the coolant; wherein a cavity is arranged in the body, and the neutrons are led out of the fast neutron reactor through the cavity; and a shielding layer, which is arranged outside the body and is used to prevent the neutrons from leaking. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Other objects and advantages of the present invention will become apparent from the following description of the present invention with reference to the accompanying drawings, which will help to provide a comprehensive understanding of the present invention.

[0008] Figure 1 is a schematic diagram of a shielding layer of a neutron extraction device according to an embodiment of the present invention;

[0009] Figure 2 is a schematic front view of a neutron extraction device body according to an embodiment of the present invention;

[0010] Figure 3 yes Figure 2 A schematic left side view of the neutron extraction device body shown;

[0011] Figure 4 is a schematic diagram of a ventilator of a neutron extraction device according to an embodiment of the present invention;

[0012] Figure 5 is a schematic diagram of installing a neutron extraction device in a reactor according to one embodiment of the present invention;

[0013] Figure 6 is a schematic diagram of a neutron detection device according to an embodiment of the present invention.

[0014] It should be noted that the drawings are not drawn to scale, and for illustrative purposes, elements of similar structure or function are generally represented by similar reference numerals throughout the drawings. It should also be noted that the drawings are only for the convenience of describing the preferred embodiments, not the invention itself. The drawings do not illustrate every aspect of the described embodiments and do not limit the scope of the invention.

[0015] In the figure, 10 is an outer container, 11 is a fixing part, 20 is a shielding layer, 30 is an inner container, 40 is a connecting part, 50 is a ventilation part, 60 is a sealing part, 70 is an in-core support, 80 is a core, 90 is a detector housing, and 91 is a detector. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiment is one embodiment of the present invention, not all embodiments. Based on the described 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.

[0017] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0018] An embodiment of the present invention provides a neutron extraction device for a fast neutron reactor, which includes a body, which is arranged in the fast neutron reactor coolant and is used to discharge the coolant; wherein a cavity is arranged in the body, and neutrons are extracted from the fast neutron reactor through the cavity.

[0019] The current fast neutron reactor uses liquid metallic sodium as a coolant. The neutron extraction device is placed in the liquid metallic sodium to displace the liquid metallic sodium at its location, thereby allowing neutrons to be extracted from the main reactor container through the cavity of the neutron extraction device.

[0020] The neutron extraction device further comprises a shielding layer 20, which is arranged outside the body and is used to prevent neutron leakage. Figure 1 is a schematic diagram of a shielding layer 20 of a neutron extraction device according to an embodiment of the present invention, see Figure 1The shielding layer 20 may be disposed on the upper and lower sides of the neutron extraction device body. Optionally, the shielding layer 20 may be a steel plate.

[0021] Figure 2 is a schematic front view of a neutron extraction device body according to an embodiment of the present invention, Figure 3 yes Figure 2 The schematic left side view of the neutron extraction device body shown in FIG. Figure 2 and Figure 3 The main body includes an outer container 10 and an inner container 30, and the outer container 10 is sleeved in the inner container 30. That is to say, the main body of the neutron extraction device is a double-layer structure, which makes the neutron extraction device highly reliable.

[0022] The body further includes a connector 40, the two ends of which are respectively connected to the outer container 10 and the inner container 30, for fixing the inner container 30 to the outer container 10. In some embodiments, the connector 40 may be a connecting plate, and the inner container 30 may be welded to the outer container 10 through the connecting plate.

[0023] The neutron extraction device also includes a fixing part 11, which is arranged on the outer container 10 and is used to fix the neutron extraction device to the support inside the reactor. Optionally, the fixing part 11 can be arranged at an angle to adapt to the space of the support inside the reactor. In an embodiment of the present invention, the fixing part 11 can be a saddle support, which refers to a support structure in which a plastic plate is partially attached to a horizontal container and is saddle-shaped. Optionally, an annular reinforcement ring can be arranged on the cross section of the support or in the vicinity thereof to increase the circumferential rigidity and strength. In an embodiment of the present invention, two saddle supports can be used to fix the neutron extraction device to the support inside the reactor. It can be ensured that the saddle supports are evenly stressed. In other embodiments, when the neutron extraction device is too long and exceeds the support range allowed by two saddle supports, the number of saddle supports can be increased, and three, four or other numbers of saddle supports can be selected. In some embodiments, one of the two saddle supports may be a fixed saddle and the other may be a movable saddle. The movable saddle is used to slide and adjust the distance between the two saddle supports when the container expands or contracts due to temperature difference, so that the container is not subjected to additional stress. The equipment will stretch when heated. In order to prevent thermal stress from being generated in the equipment, the fixed saddle and the movable saddle are used together to provide elongation space for the equipment to stretch when heated. Optionally, a base pad can be installed under the floor of the movable saddle. The base pad is flat and smooth, so that the equipment can freely expand and contract when the temperature changes. In other embodiments, both saddle supports can be fixed saddles. The saddle support can be fixed to the sealing partition supported in the pile by bolts. Under seismic loads, the fastening bolts of the neutron extraction device can reliably bear the load, so that the neutron extraction device can be reliably fixed in the reactor.

[0024] Argon is provided in the cavity, and argon can be used as a shielding gas during the manufacturing process of the neutron extraction device. For example, in the process of welding the inner container 30 to the outer container 10 through the connector 40, argon can be used as a shielding gas to avoid welding defects and thus ensure the quality of welding.

[0025] The neutron extraction device further includes a ventilator 50. Figure 4 is a schematic diagram of a vent 50 of a neutron extraction device according to an embodiment of the present invention, see Figure 4 , the vent 50 is connected to the body and is used to replace the argon in the cavity. In some embodiments, the vent 50 can be connected to the inner container 30. In other embodiments, two vents 50 can be provided, one of which is connected to the inner container 30 and the other is connected to the outer container 10, for replacing the argon in the space formed between the inner container 30 and the outer container 10. In other embodiments, the vent 50 can also be connected to the inner container 30, and an opening is provided at the portion of the vent 50 located between the inner container 30 and the outer container 10, for replacing the argon in the space formed between the inner container 30 and the outer container 10.

[0026] See also Figure 2 , seals 60 are provided at both ends of the body, which are used to seal the cavity in the body of the neutron extraction device, prevent the coolant in the reactor from entering the device, shield the neutrons passing through the device, and affect the neutron extraction effect. The seal 60 can be a head, which is a component used to seal the end of the container to isolate the internal and external media. In an embodiment of the present invention, the head can be a convex head, that is, a head with a convex outer surface. Optionally, the seal 60 can be an elliptical head. In other embodiments, the head can also be a combined bottom head with the convex surface facing inward. The seal 60 can be welded to both ends of the body. In an embodiment of the present invention, seals 60 are provided at both ends of the outer container 10, and seals 60 are provided at both ends of the inner container 30. The shapes of the two seals 60 may not be exactly the same, and the middle parts of the two seals 60 may contact each other, so that there is a part of the two seals 60 that overlaps each other without a gap. In other embodiments, the two seals 60 can be heads with exactly the same shape, so that there is a gap between the two seals 60.

[0027] Figure 5 is a schematic diagram of installing a neutron extraction device in a reactor according to an embodiment of the present invention, see Figure 5The main body can be set to two, one of which is set above the other body, used to drain the coolant in the fast neutron reactor, and the internal cavity between the two bodies forms a neutron extraction channel, so that neutrons are extracted outside the fast neutron reactor. The diameters of the two neutron extraction device bodies are consistent. Since the neutron extraction device is set on the side of the elevator channel in the reactor, there is space on the side of the elevator channel for extracting neutrons. The elevator is used for loading and unloading, and is used in conjunction with the material changer and the transporter. The elevator receives the new components sent by the transporter. The material changer puts the new components in the elevator bucket into the core and puts the spent components into the elevator bucket. The transporter then takes out the spent components in the elevator bucket and puts in the new components, and the operation is cyclic. The elevator is set at the upper support plate in the pile. In order to adapt to the space on the side of the elevator channel on the upper support plate in the pile, the length of the neutron extraction device body located at the upper part is shorter than that of the neutron extraction device body located at the lower part.

[0028] The neutron extraction device provided in the embodiment of the present invention is applied in the China Demonstration Fast Reactor. The position where the neutron extraction device is set is determined, and the diameter and length of the neutron extraction device body are determined according to the size of the space where the position is located and the need to drain the coolant. When the reactor is operating normally, the neutron extraction device is not under pressure. Under reactor replacement, gas heating, sodium filling, full power operation, and transient conditions, the neutron extraction device is strength checked and stability checked respectively. The neutron extraction device can maintain structural integrity under different operating conditions of the reactor.

[0029] An embodiment of the present invention provides a fast neutron reactor, including: an in-core support 70 and the neutron extraction device, wherein the neutron extraction device is fixed to the in-core support 70 .

[0030] The in-core support 70 includes a partition, and the neutron extraction device is fixed to the partition.

[0031] The fast neutron reactor further includes a core 80, and the core 80 and the neutron extraction device are arranged at the same height.

[0032] The fast neutron reactor also includes a hoist, and a neutron extraction device is arranged on the side of the hoist passage.

[0033] An embodiment of the present invention provides a neutron detection device for a fast neutron reactor. Figure 6 is a schematic diagram of a neutron detection device according to an embodiment of the present invention, see Figure 6The neutron detection device includes a detector housing 90 and a neutron extraction device. The detector housing 90 includes at least one detector 91. The detector 91 and the neutron extraction device are arranged at the same height, and are used to allow the neutrons extracted from the neutron extraction device to enter the detector, so that the detector detects the neutrons. Optionally, the detector 91 can be a source range detector, an intermediate range detector, or a power range detector. In some embodiments, the detector housing 90 can include a source range detector, an intermediate range detector, and a power range detector. The measurement ranges of the three ranges overlap with each other, and the measurement range from reactor startup to full power operation can be covered without blind spots.

[0034] The detector 91 further includes a detection channel, which is arranged at the same height as the neutron extraction device. That is, the detection channel and the neutron extraction channel formed by the neutron extraction device body are arranged at the same height. The detection channel and the neutron extraction channel may be connected or not connected.

[0035] The embodiment of the present invention provides a neutron detection method for a fast neutron reactor, comprising: placing a neutron detector outside the main container of the fast neutron reactor so that the neutron detector and the neutron extraction device are arranged at the same height; the neutrons in the fast neutron reactor are extracted from the main container of the fast neutron reactor by the neutron extraction device and reach the neutron detector; and the neutrons are detected. This neutron detection method places the detector outside the main container of the reactor for off-core measurement. The detector is placed outside the main container of the reactor, the working environment is moderate, it is easy to debug and maintain, the cost is low, and the neutron extraction channel solves the problem that the detector is far from the core so that the neutron signal is not easy to reach the detector. The off-core measurement can continuously monitor the neutrons, and the measured neutron injection rate signal can be used for the control and protection of the nuclear power plant.

[0036] Regarding the embodiments of the present invention, it should also be noted that, in the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0037] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A neutron extraction device for a fast neutron reactor, characterized in that: include: A body, the body being disposed in the fast neutron reactor coolant and used to discharge the coolant; Wherein, a cavity is provided in the body, and the neutrons are led out of the fast neutron reactor through the cavity; a shielding layer (20), the shielding layer (20) being arranged outside the body and used to prevent leakage of the neutrons; Sealing members (60) are provided at both ends of the body, which are used to seal the cavity in the body of the neutron extraction device, thereby preventing the coolant in the reactor from entering the neutron extraction device, shielding the neutrons passing through the neutron extraction device, and affecting the neutron extraction effect; The bodies are provided in pairs, wherein one of the bodies is provided above the other body, and is used to discharge the coolant in the fast neutron reactor to form a neutron extraction channel so that the neutrons are extracted outside the fast neutron reactor.

2. The neutron extraction device according to claim 1, characterized in that: The body comprises an outer container (10) and an inner container (30), and the outer container (10) is sleeved on the inner container (30).

3. The neutron extraction device according to claim 2, characterized in that: The main body further comprises a connecting piece (40), and two ends of the connecting piece (40) are respectively connected to the outer container (10) and the inner container (30).

4. The neutron extraction device according to claim 2, characterized in that: It also comprises a fixing part (11), wherein the fixing part (11) is arranged on the outer container (10).

5. The neutron extraction device according to claim 1, characterized in that: Argon gas is arranged in the cavity.

6. The neutron extraction device according to claim 5, characterized in that: It also includes a vent (50), which is connected to the body and is used to replace the argon gas in the cavity.

7. The neutron extraction device according to claim 1, characterized in that: The length of the main body arranged at the top is shorter than the length of the other main body.

8. A fast neutron reactor, characterized in that: include: In-pile support (70); The neutron extraction device according to any one of claims 1 to 7, wherein the neutron extraction device is fixed to the in-pile support (70).

9. The fast neutron reactor according to claim 8, characterized in that: The in-pile support (70) includes a partition, and the neutron extraction device is fixed to the partition.

10. The fast neutron reactor according to claim 8, characterized in that: It also includes a core (80), wherein the core (80) and the neutron extraction device are arranged at the same height.

11. The fast neutron reactor according to claim 8, characterized in that: It also includes a hoist, and the neutron extraction device is arranged on the side of the hoist channel.

12. A neutron detection device for a fast neutron reactor, characterized in that: include: A detector accommodating portion (90), wherein the detector accommodating portion (90) comprises at least one detector (91); The neutron extraction device according to any one of claims 1 to 7, wherein the detector (91) and the neutron extraction device are arranged at the same height.

13. The neutron detection device according to claim 12, characterized in that: The detector (91) further comprises a detection channel, wherein the detection channel and the neutron extraction device are arranged at the same height.

14. A neutron detection method for a fast neutron reactor, characterized in that: include: Placing a neutron detector outside the fast neutron reactor main container so that the neutron detector and the neutron extraction device are arranged at the same height; Neutrons in the fast neutron reactor are led out of the main container of the fast neutron reactor through the neutron extraction device and reach the neutron detector; detecting the neutrons; The neutron extraction device is the neutron extraction device described in any one of claims 1-7.

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