High-temperature neutron moderation rod and preparation method thereof

Abstract

The invention provides a high-temperature neutron moderation rod which comprises a cladding, a mounting cavity is formed in the cladding, and a plurality of spacers are arranged in the mounting cavity and divide the mounting cavity into a plurality of pellet mounting cavities; and a metal hydride core block is arranged in the core block mounting cavity. The invention discloses a preparation method of a high-temperature neutron moderation rod. The preparation method comprises the following steps: loading a metal hydride pellet and a spacer into a cladding; under the vacuum condition, the cladding is subjected to hole blocking and seal welding treatment, and the moderation rod subjected to hole blocking and seal welding is obtained; performing hot isostatic pressing treatment on the moderated rod subjected to hole plugging and sealing welding, and integrally welding the spacer and the cladding to obtain the moderated rod subjected to hot isostatic pressing treatment; and removing a surface oxide layer of the moderated rod subjected to hot isostatic pressing treatment to obtain the metal hydride moderated rod. The metal hydride core blocks are mutually isolated and independently sealed, compared with a moderation rod of a common structure, under the temperature gradient, hydrogen in the metal hydride core blocks cannot migrate for a long distance, and therefore it is ensured that hydrogen distribution in the moderation rod is relatively stable and controllable.

Description

Technical Field

[0001] This application belongs to the technical field of nuclear reactor fuel rods, and particularly relates to a high-temperature neutron moderator rod and a preparation method thereof. Background Art

[0002] Metal hydrides have a high hydrogen content, a high hydrogen decomposition temperature, and a high neutron moderation efficiency. When used as a moderator in a new type of reactor, they can significantly reduce the fuel loading in the reactor core. They are important candidate materials for solid moderators in new high-temperature reactors.

[0003] The high-temperature thermal stability of metal hydrides is a key performance of solid moderators during service. Metal hydrides have a risk of hydrogen loss at high temperatures. In addition, there is a risk of hydrogen migration in metal hydrides under the condition of a temperature gradient. The equilibrium hydrogen partial pressure of metal hydrides increases with the increase in temperature. During the operation of a reactor, there are temperature gradients in both the axial and radial directions of the reactor core. When the hydrogen content in the metal hydride in the moderator rod is the same, the equilibrium hydrogen partial pressure at the high-temperature end is high, and the equilibrium hydrogen partial pressure at the low-temperature end is low. Hydrogen atoms migrate from the high-temperature end to the low-temperature end, resulting in a decrease in the hydrogen content at the high-temperature end of the moderator rod and an increase in the hydrogen content at the low-temperature end. This causes changes in the neutron moderation ability at different positions of the reactor, deviates from the initial design state, affects the uniformity of the reactor power distribution, and increases the difficulty of reactor design and control. Summary of the Invention

[0004] Therefore, the purpose of this application is to provide a high-temperature neutron moderator rod and a preparation method thereof, which can at least solve the problem of reactor reactivity changes caused by hydrogen migration in metal hydride moderator rods under a temperature gradient.

[0005] To solve the above problems, a first aspect of this application provides a high-temperature neutron moderator rod, including a cladding, a spacer, and a metal hydride pellet; an installation chamber is formed inside the cladding, and a plurality of spacers are arranged in the installation chamber to divide the installation chamber into a plurality of pellet installation chambers; the metal hydride pellets are arranged in the pellet installation chambers, and the spacers are used to seal the pellets in independent pellet installation chambers so that hydrogen in the metal hydride pellets does not undergo long-distance migration.

[0006] Optionally, the metal hydride pellet is a mixture of one or more metal hydrides such as zirconium hydride, cerium hydride, and yttrium hydride.

[0007] Optionally, the cladding material is one of stainless steel and nickel alloy; the spacer is made of the same material as the cladding.

[0008] A second aspect of this application provides a preparation method of a high-temperature neutron moderator rod, and the above high-temperature neutron moderator rod is obtained by the preparation method of the high-temperature neutron moderator rod.

[0009] Optionally, the preparation method includes:

[0010] Loading the metal hydride pellets and the spacers into the cladding; under vacuum conditions, performing plugging and sealing welding on the cladding to obtain a moderating rod after plugging and sealing welding;

[0011] Performing hot isostatic pressing on the moderating rod after plugging and sealing welding to weld the spacer and the cladding into one body, obtaining a moderating rod after hot isostatic pressing;

[0012] Removing the surface oxide layer of the moderating rod after hot isostatic pressing to obtain a metal hydride moderating rod.

[0013] Optionally, the preparation method further includes:

[0014] Preparing a metal hydride blank by using a direct hydrogen doping method or a powder metallurgy method;

[0015] Machining the metal hydride blank to obtain metal hydride pellets.

[0016] Optionally, the step of loading the metal hydride pellets and the spacers into the cladding is specifically:

[0017] Loading the metal hydride pellets and the spacers into the cladding alternately so that one metal hydride pellet is arranged between adjacent spacers.

[0018] Optionally, the vacuum degree under the vacuum conditions is 10 -4 Pa to 10 -2 Pa.

[0019] Optionally, the step of performing hot isostatic pressing on the moderating rod after plugging and sealing welding to weld the spacer and the cladding into one body to obtain a moderating rod after hot isostatic pressing is specifically:

[0020] Putting one or more moderating rods after plugging and sealing welding into a hot isostatic pressing furnace for hot isostatic pressing to weld the spacer and the cladding into one body, obtaining a moderating rod after hot isostatic pressing;

[0021] Wherein, the temperature of the hot isostatic pressing furnace is 900 °C to 1050 °C.

[0022] Optionally, the step of removing the surface oxide layer of the moderating rod after hot isostatic pressing to obtain a metal hydride moderating rod is specifically:

[0023] Performing pickling treatment on the surface of the cladding of the moderating rod after hot isostatic pressing to remove the oxide layer on the surface of the cladding, obtaining a finished metal hydride moderating rod.

[0024] By the above technical solution, the invention of the present application has at least the following beneficial effects:

[0025] A high-temperature neutron moderator rod and a preparation method thereof disclosed in an embodiment of the present application divide a cladding into a plurality of pellet installation cavities through spacers, place metal hydride pellets in the pellet installation cavities, and each metal hydride pellet is isolated from each other by a spacer and separately sealed. The highest operating temperature of the moderator rod can reach 1000°C, preventing the migration of hydrides under a temperature gradient. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the high-temperature neutron moderator rod according to an embodiment of the present application;

[0027] Figure 2 It is a flowchart of the preparation method of the high-temperature neutron moderator rod according to an embodiment of the present application.

[0028] The reference numerals are represented as:

[0029] 1. Cladding; 2. Spacer; 3. Pellet. Detailed Embodiments

[0030] In the description of the present application, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0031] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0032] In the present application, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] The preferred embodiments of the present invention will be described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0034] The spacer 2 divides the cladding 1 into multiple pellet installation cavities, and the metal hydride pellets 3 are placed in the pellet installation cavities. Each metal hydride pellet 3 is isolated from each other by the spacer 2 and separately sealed. The maximum operating temperature of the moderator rod can reach 1000°C, preventing the migration of hydrides under temperature gradients.

[0035] Referring to Figure 1 As shown, according to the first aspect of the embodiments of the present application, a high-temperature neutron moderator rod is provided, including a cladding 1, a spacer 2, and metal hydride pellets 3; an installation chamber is formed inside the cladding 1, and a plurality of spacers 2 are arranged in the installation chamber, dividing the installation chamber into multiple pellet installation cavities; metal hydride pellets 3 are arranged in the pellet installation cavities, and the spacer 2 is used to seal the metal hydride pellets 3 in independent pellet installation cavities, so that the hydrogen in the metal hydride pellets 3 does not undergo long-distance migration.

[0036] Among them, a plurality of spacers 2 are arranged in the installation chamber, dividing the installation chamber into multiple pellet installation cavities; in this embodiment, the plurality of spacers 2 divide the installation chamber into multiple pellet installation cavities of the same size; First, it effectively disperses stress, avoids stress concentration, and reduces the risk of structural damage caused by stress concentration; Second, the partition can ensure that the thermal environment around each pellet is relatively independent and uniform. In a nuclear reactor, the moderator rod needs to efficiently conduct heat to maintain the thermal balance of the reactor. Through the isolation of the partition, each pellet can absorb and release heat more evenly, avoiding local overheating or overcooling. Third, through the isolation of the partition, it can ensure that the hydrogen concentration in each small pellet installation cavity is relatively stable, thereby improving the performance and service life of the metal hydride pellets.

[0037] In another embodiment, the metal hydride pellet 3 is a mixture of one or more metal hydrides such as zirconium hydride, cerium hydride, and yttrium hydride.

[0038] Zirconium hydride has a high hydrogen content and a low neutron absorption cross-section, and the operating temperature can reach 800°C; the neutron absorption cross-section of cerium hydride is slightly higher than that of zirconium hydride, and the operating temperature can reach 900°C; yttrium hydride is currently the metal hydride with the highest known decomposition temperature, and the use temperature can reach above 1000°C, and the neutron absorption cross-section is moderate.

[0039] In another embodiment, the material of the cladding 1 is one of stainless steel and nickel alloy; the spacer 2 is made of the same material as the cladding 1.

[0040] Among them, stainless steel has good mechanical properties and is inexpensive, and its service temperature generally does not exceed 900°C; nickel alloy has good high-temperature properties and good mechanical properties, and its service temperature can reach 1000°C.

[0041] Among them, the spacer 2 and the cladding 1 are made of the same material; First, when diffusion welding is carried out with the same material, the mechanical properties (such as strength, toughness, etc.) of the welded joint can be consistent with those of the cladding 1. Second, diffusion welding of the same material can achieve good atomic diffusion at a lower temperature, thereby ensuring a higher strength at the connection between the spacer 2 and the cladding 1. Third, the thermal expansion coefficients of the same material are the same. Therefore, during the welding process, the stress distribution caused by thermal expansion is more uniform, effectively reducing the thermal stress and deformation generated during the welding process, thereby improving the quality and stability of the joint between the spacer 2 and the cladding 1.

[0042] In the second aspect of the present application, a preparation method of a high-temperature neutron moderator rod is provided, and the high-temperature neutron moderator rod is obtained by the preparation method of the high-temperature neutron moderator rod.

[0043] The high-temperature neutron moderator rod produced by this method can reach a maximum temperature of 1000°C. Under a temperature gradient, hydrogen in yttrium hydride will not undergo long-distance migration, thereby ensuring that the hydrogen distribution in the moderator rod is relatively stable and controllable.

[0044] As Figure 2 shown, in another embodiment, the preparation method includes:

[0045] Step S1, loading the metal hydride pellets 3 and the spacers 2 into the cladding 1; under vacuum conditions, performing plugging and sealing welding on the cladding 1 to obtain the moderating rod after plugging and sealing welding.

[0046] Specifically: The metal hydride pellets 3 and the spacers 2 are alternately loaded into the cladding 1 so that one metal hydride pellet 3 is arranged between adjacent spacers 2.

[0047] That is to say, the installation chamber of the cladding is divided into multiple pellet installation chambers by the spacers 2, and the metal hydride pellets 3 are loaded into the divided pellet installation chambers for sealing; compared with the moderating rod with a common structure, under a temperature gradient, hydrogen in the metal hydride pellets 3 will not undergo long-distance migration, thereby ensuring that the hydrogen distribution in the moderating rod is relatively stable and controllable.

[0048] Among them, the vacuum degree is 10 -4 Pa to 10 -2 Pa.

[0049] Under vacuum conditions, plug the holes of the cladding 1 and perform sealing welding. On the one hand, ensure that the inside of the cladding is completely isolated from the external environment, prevent external gases from entering the inside of the cladding tube, and ensure its good sealing performance. On the other hand, performing plugging and welding under vacuum conditions can minimize the impurities inside the cladding and improve the service performance and service life of the moderator rod.

[0050] Step S2: Perform hot isostatic pressing on the moderator rod after plugging and sealing welding to weld the spacer 2 and the cladding 1 into one body, obtaining the moderator rod after hot isostatic pressing.

[0051] Specifically: Put one or more moderator rods into a hot isostatic pressing furnace for hot isostatic pressing. Under diffusion welding, the spacer 2 and the cladding 1 are welded into one body to form multiple sealed core block installation cavities.

[0052] Among them, the temperature of the hot isostatic pressing furnace is 900°C to 1050°C.

[0053] Step S3: Remove the surface oxide layer of the moderator rod after hot isostatic pressing to obtain a metal hydride moderator rod.

[0054] Specifically: Perform pickling treatment on the surface of the cladding 1 of the moderated rod after hot isostatic pressing to remove the oxide layer on the surface of the cladding 1, obtaining the finished product of the metal hydride moderator rod.

[0055] As a refinement and extension of the specific implementation manner of the above embodiment, in order to fully illustrate the specific implementation process of this embodiment, another preparation method of a high-temperature neutron moderator rod is provided, including:

[0056] Step S1: Prepare a metal hydride blank by using a direct hydrogen doping method or a powder metallurgy method.

[0057] When preparing a metal hydride blank by using a direct hydrogen doping method, on the one hand, by precisely controlling the purity of hydrogen and the reaction conditions, a high-purity and crack-free metal hydride blank is prepared. On the other hand, hydrogen directly reacts with the metal, which can avoid introducing new impurities.

[0058] When preparing a metal hydride blank by using a powder metallurgy method, on the one hand, by precisely controlling the particle size of the powder and the molding pressure, high-precision dimensional control can be achieved, reducing the amount of subsequent machining and improving the material utilization rate. On the other hand, the powder metallurgy method can quickly prepare metal hydrides, with no crack risk and a high yield.

[0059] Step S2: Perform machining on the metal hydride blank to obtain a metal hydride core block 3.

[0060] The purpose of machining the metal oxide blank is to obtain a metal hydride core block 3 that meets the design size requirements.

[0061] Step S3: Load the metal hydride pellets 3 and spacers 2 into the cladding 1; under vacuum conditions, perform plugging and welding on the cladding 1 to obtain a moderating rod after plugging and welding.

[0062] Specifically: Alternately load the metal hydride pellets 3 and spacers 2 into the cladding 1 so that one metal hydride pellet 3 is arranged between adjacent spacers 2.

[0063] That is to say, the installation chamber of the cladding is divided into multiple pellet installation chambers by the spacers 2, and the metal hydride pellets 3 are loaded into the separated pellet installation chambers for sealing; compared with a moderating rod of a common structure, under a temperature gradient, hydrogen in the metal hydride pellets 3 will not undergo long-distance migration, thereby ensuring that the hydrogen distribution in the moderating rod is relatively stable and controllable.

[0064] Among them, the vacuum degree is 10 -4 Pa to 10 -2 Pa.

[0065] Performing plugging and welding on the cladding 1 under vacuum conditions, on the one hand, ensures that the inside of the cladding is completely isolated from the external environment, prevents external gas from entering the inside of the cladding tube, and ensures its good sealing performance; on the other hand, plugging and welding under vacuum conditions can minimize the impurities inside the cladding and improve the service performance and service life of the moderating rod.

[0066] Step S4: Perform hot isostatic pressing on the moderating rod after plugging and welding to weld the spacer 2 and the cladding 1 into one body to obtain a moderating rod after hot isostatic pressing. Specifically: Put one or more moderating rods into a hot isostatic pressing furnace for hot isostatic pressing. Under diffusion welding, the spacer 2 and the cladding 1 are welded into one body to form multiple sealed pellet installation chambers;

[0067] Among them, the temperature of the hot isostatic pressing furnace is 900 °C to 1050 °C.

[0068] Step S5: Remove the surface oxide layer of the moderating rod after hot isostatic pressing to obtain a metal hydride moderating rod.

[0069] Specifically: Perform pickling treatment on the cladding 1 of the moderating rod after hot isostatic pressing to remove the oxide layer on the surface of the cladding 1 to obtain a finished metal hydride moderating rod.

[0070] Example 1

[0071] In this example, the metal hydride pellet 3 uses a yttrium hydride solid moderator pellet with a maximum operating temperature of 950 °C; the spacer 2 and the cladding 1 are made of stainless steel.

[0072] A method for preparing a high-temperature neutron moderating rod includes the following steps:

[0073] Step S1: Prepare a yttrium hydride blank using the direct hydrogen permeation method;

[0074] Step S2: Machine the yttrium hydride blank to obtain yttrium hydride pellets that meet the design size requirements;

[0075] Step S3: Load the yttrium hydride pellets and spacer 2 into the cladding 1; under vacuum conditions, perform plugging and sealing welding on the cladding 1 to keep the inside of the cladding 1 in a high-vacuum sealed state, obtaining a moderating rod after plugging and sealing welding;

[0076] Step S4: Place one or more moderating rods after plugging and sealing welding into a hot isostatic pressing furnace, perform hot isostatic pressing on the moderating rods after plugging and sealing welding, diffusion-weld the spacer 2 and the cladding 1 into an integral structure, and form a sealed pellet installation cavity;

[0077] Among them, the processing pressure of the hot isostatic pressing furnace is 150 MPa and the temperature is 950 °C.

[0078] Step S5: Pickle the surface of the cladding 1 of the moderating rod after hot isostatic pressing to remove the oxides on the surface of the cladding 1, obtaining a finished yttrium hydride moderating rod.

[0079] Example 2

[0080] In this example, the metal hydride pellet 3 uses a cerium hydride solid moderator pellet, with a maximum operating temperature of 900 °C; the spacer 2 and the cladding 1 are made of stainless steel.

[0081] A method for preparing a high-temperature neutron moderating rod includes the following steps:

[0082] Step S1: Prepare a cerium hydride blank using the direct hydrogen permeation method;

[0083] Step S2: Machine the cerium hydride blank to obtain cerium hydride pellets that meet the design size requirements;

[0084] Step S3: Load the cerium hydride pellets and spacer 2 into the cladding 1; under vacuum conditions, perform plugging and sealing welding on the cladding 1 to keep the inside of the cladding 1 in a high-vacuum sealed state, obtaining a moderating rod after plugging and sealing welding;

[0085] Step S4: Place one or more moderating rods after plugging and sealing welding into a hot isostatic pressing furnace, perform hot isostatic pressing on the moderating rods after plugging and sealing welding, diffusion-weld the spacer 2 and the cladding 1 into an integral structure, and form a sealed pellet installation cavity;

[0086] Among them, the processing pressure of the hot isostatic pressing furnace is 150 MPa and the temperature is 950 °C.

[0087] Step S5, pickling the surface of the cladding 1 of the moderating rod after hot isostatic pressing to remove the oxides on the surface of the cladding 1, and obtaining the finished product of the cerium hydride moderating rod.

[0088] Example 3

[0089] In this example, the metal hydride pellets 3 are made of yttrium hydride solid moderator pellets, with a maximum service temperature of 1000 °C; the spacer 2 and the cladding 1 are made of nickel alloy.

[0090] A preparation method of a high-temperature neutron moderating rod includes the following steps:

[0091] Step S1, preparing a yttrium hydride blank by a direct hydrogen permeation method;

[0092] Step S2, machining the yttrium hydride blank to obtain yttrium hydride pellets that meet the design size requirements;

[0093] Step S3, loading the yttrium hydride pellets and the spacer 2 into the cladding 1; under vacuum conditions, performing plugging and sealing welding on the cladding 1 to keep the inside of the cladding 1 in a high-vacuum sealed state, and obtaining the moderating rod after plugging and sealing welding;

[0094] Step S4, putting one or more moderating rods after plugging and sealing welding into a hot isostatic pressing furnace, performing hot isostatic pressing on the matrix of the moderating rod after plugging and sealing welding, diffusion welding the spacer 2 and the cladding 1 into an integral structure, and forming a sealed pellet installation cavity;

[0095] Among them, the processing pressure of the hot isostatic pressing furnace is 150 MPa and the temperature is 1050 °C.

[0096] Step S5, pickling the surface of the cladding 1 of the moderating rod after hot isostatic pressing to remove the oxides on the surface of the cladding 1, and obtaining the finished product of the yttrium hydride moderating rod.

[0097] Example 4

[0098] In this example, the metal hydride pellets 3 are made of zirconium hydride solid moderator pellets, with a maximum service temperature of 900 °C; the spacer 2 and the cladding 1 are made of stainless steel.

[0099] A preparation method of a high-temperature neutron moderating rod includes the following steps:

[0100] Step S1, preparing a zirconium hydride blank by a direct hydrogen permeation method;

[0101] Step S2, machining the zirconium hydride blank to obtain zirconium hydride pellets that meet the design size requirements;

[0102] Step S3, load the zirconium hydride pellets and the spacer 2 into the cladding 1; under vacuum conditions, perform plugging and welding on the cladding 1 to keep the inside of the cladding 1 in a high-vacuum sealed state, obtaining a moderating rod after plugging and welding.

[0103] Step S4, put one or more moderating rods after plugging and welding into a hot isostatic pressing furnace, perform hot isostatic pressing on the moderating rods after plugging and welding, diffusion-weld the spacer 2 and the cladding 1 into an integral structure, forming a sealed pellet installation cavity.

[0104] Among them, the processing pressure of the hot isostatic pressing furnace is 150 MPa and the temperature is 950 °C.

[0105] Step S5, pickle the surface of the cladding 1 of the moderating rod after hot isostatic pressing to remove the oxides on the surface of the cladding 1, obtaining a finished zirconium hydride moderating rod.

[0106] Example 5

[0107] In this example, the metal hydride pellets 3 are cerium hydride solid moderator pellets with a maximum service temperature of 1000 °C; the spacer 2 and the cladding 1 are made of nickel alloy.

[0108] A preparation method of a high-temperature neutron moderating rod includes the following steps:

[0109] Step S1, prepare a cerium hydride blank by the direct hydrogen permeation method;

[0110] Step S2, perform machining on the cerium hydride blank to obtain cerium hydride pellets that meet the design size requirements;

[0111] Step S3, load the cerium hydride pellets and the spacer 2 into the cladding 1; under vacuum conditions, perform plugging and welding on the cladding 1 to keep the inside of the cladding 1 in a high-vacuum sealed state, obtaining a moderating rod after plugging and welding.

[0112] Step S4, put one or more moderating rods after plugging and welding into a hot isostatic pressing furnace, perform hot isostatic pressing on the moderating rods after plugging and welding, diffusion-weld the spacer 2 and the cladding 1 into an integral structure, forming a sealed pellet installation cavity.

[0113] Among them, the processing pressure of the hot isostatic pressing furnace is 150 MPa and the temperature is 1000 °C.

[0114] Step S5, pickle the surface of the cladding 1 of the moderating rod after hot isostatic pressing to remove the oxides on the surface of the cladding 1, obtaining a finished cerium hydride moderating rod.

[0115] The cladding 1 is divided into a plurality of pellet mounting cavities by the spacer 2, and the metal hydride pellets 3 are placed in the pellet mounting cavities. Each metal hydride pellet 3 is isolated from each other and individually sealed by the spacer 2. The maximum operating temperature of the moderator rod can reach 1000°C to prevent the migration of hydrides under the temperature gradient.

[0116] It is easily understood by those skilled in the art that, on the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0117] The above are only the preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above is only the preferred implementation manner of the present application. It should be noted that for those of ordinary skill in the art in the technical field, several improvements and variations can be made without departing from the technical principle of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A high-temperature neutron moderating rod, characterized in that, It includes a cladding (1), spacers (2), and metal hydride pellets (3); an installation chamber is formed inside the cladding (1), and a plurality of spacers (2) are arranged in the installation chamber, dividing the installation chamber into a plurality of pellet installation chambers; the metal hydride pellets (3) are arranged in the pellet installation chambers, and the spacers (2) are used to seal the pellets (3) in independent pellet installation chambers, so that hydrogen in the metal hydride pellets (3) does not undergo long-distance migration.

2. The high-temperature neutron moderator rod according to claim 1, characterized in that, The metal hydride pellets (3) are one or a mixture of several metal hydrides such as zirconium hydride, cerium hydride, and yttrium hydride.

3. A high-temperature neutron moderating rod according to claim 1, characterized in that, The material of the cladding (1) is one of stainless steel and nickel alloy; the spacer (2) is made of the same material as the cladding (1).

4. A preparation method of a high-temperature neutron moderator rod, characterized in that, The high-temperature neutron moderator rod described in any one of claims 1 to 3 is obtained by a preparation method of a high-temperature neutron moderator rod.

5. The preparation method of the high-temperature neutron moderating rod according to claim 4, characterized in that, The preparation method includes: Loading the metal hydride pellets (3) and the spacers (2) into the cladding (1); under vacuum conditions, performing plugging and sealing welding on the cladding (1) to obtain a moderator rod after plugging and sealing welding. Performing hot isostatic pressing on the moderator rod after plugging and sealing welding to weld the spacer (2) and the cladding (1) into one body to obtain a moderator rod after hot isostatic pressing. Removing the surface oxide layer of the moderator rod after hot isostatic pressing to obtain a metal hydride moderator rod.

6. The preparation method of a high-temperature neutron moderating rod according to claim 5, characterized in that, The preparation method further includes: Preparing a metal hydride blank by a direct hydrogen doping method or a powder metallurgy method. Performing machining on the metal hydride blank to obtain the metal hydride pellets (3).

7. The preparation method of a high-temperature neutron moderating rod according to claim 5, characterized in that, The step of loading the metal hydride pellets (3) and the spacers (2) into the cladding (1) is specifically: Alternately loading the metal hydride pellets (3) and the spacers (2) into the cladding (1) so that one metal hydride pellet (3) is arranged between adjacent spacers (2).

8. The preparation method of a high-temperature neutron moderator rod according to claim 5, characterized in that, The degree of vacuum under the vacuum condition is 10 -4 Pa to 10 -2 Pa.

9. The preparation method of a high-temperature neutron moderator rod according to claim 5, characterized in that, The step of performing hot isostatic pressing on the moderator rod after plugging and sealing welding to weld the spacer (2) and the cladding (1) into one body to obtain a moderator rod after hot isostatic pressing is specifically: Putting one or more moderator rods after plugging and sealing welding into a hot isostatic pressing furnace for hot isostatic pressing to weld the spacer (2) and the cladding (1) into one body to obtain a moderator rod after hot isostatic pressing. Wherein, the temperature of the hot isostatic pressing furnace is 900°C to 1050°C.

10. The preparation method of a high-temperature neutron moderating rod according to claim 5, characterized in that, The step of removing the surface oxide layer of the moderator rod after hot isostatic pressing to obtain a metal hydride moderator rod is specifically: Performing pickling treatment on the surface of the cladding (1) of the moderator rod after hot isostatic pressing to remove the oxide layer on the surface of the cladding (1) to obtain a finished metal hydride moderator rod.

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