阅读说明：本技术 屏蔽结构、屏蔽组件以及钠冷快堆 (Shielding structure, shielding assembly and sodium-cooled fast reactor ) 是由 夏宇 刘兆阳 徐海涛 燕春光 孙帅 王事喜 王毅 孙刚 邓夏 王明政 张东辉 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种屏蔽结构、屏蔽组件以及钠冷快堆。屏蔽结构包括沿其径向排布的多圈屏蔽件,每圈屏蔽件由围成一圈的多根石墨屏蔽棒组成,其中每根石墨屏蔽棒由多根石墨棒沿轴向拼接而成,沿屏蔽结构的径向排布的多根石墨屏蔽棒的拼缝位置不完全相同。本发明的技术方案可减少部分中子经由石墨棒的拼缝位置向外逸出,降低了钠冷快堆堆本体的剂量水平。(The invention discloses a shielding structure, a shielding assembly and a sodium-cooled fast reactor. The shielding structure comprises a plurality of circles of shielding pieces which are radially arranged along the shielding structure, each circle of shielding piece comprises a plurality of graphite shielding rods which are enclosed into a circle, each graphite shielding rod is formed by splicing the plurality of graphite rods along the axial direction, and the splicing positions of the plurality of graphite shielding rods which are radially arranged along the shielding structure are not identical. The technical scheme of the invention can reduce the outward escape of partial neutrons from the abutted seam position of the graphite rod, and reduce the dosage level of the sodium-cooled fast reactor body.)

1. A shielding structure of a reactor, which is characterized in that the shielding structure comprises a plurality of turns of shielding pieces which are arranged along the radial direction of the shielding structure, each turn of shielding piece is composed of a plurality of graphite shielding rods which form a turn, wherein

Every graphite shielding rod is formed by the concatenation of many graphite rods along the axial, follows the piece seam position of many graphite shielding rods that shielding structure's radial arrangement is not identical.

2. The shielding structure of claim 1, wherein the splicing positions of the graphite shielding rods of the same circle of shielding members are the same; the abutted seam positions of the graphite shielding rods of two adjacent circles of shielding parts are staggered mutually.

3. The shielding structure of claim 2, wherein the splicing positions of the graphite shielding rods of different turns of shielding members are staggered from each other.

4. The shielding structure of claim 3, wherein the intervals between the splicing positions of the graphite shielding rods of two adjacent turns of shielding parts are the same.

5. The shielding structure of claim 4, wherein each of the graphite shielding rods is formed by splicing two graphite rods in an axial direction.

6. The shielding structure of claim 5, wherein the two graphite rods spliced to form the graphite shielding rod are provided with concave holes on the axial end face of one graphite rod and convex blocks on the axial end face of the other graphite rod, and the two graphite rods are spliced together through splicing and inserting matching of the concave holes and the convex blocks.

7. The shielding structure of claim 6, wherein the depth of the concave hole is the same as the height of the boss, and is smaller than the distance between the splicing positions of the graphite shielding rods of two adjacent turns of shielding pieces.

8. The shielding structure of claim 1, wherein the number of turns of the shielding member is 2 to 6 turns.

9. The shielding structure of claim 1, further comprising: and a plurality of stainless steel rods which are dispersedly arranged on the inner side and the outer side of the multi-turn shielding piece.

10. The shielding structure of claim 9, wherein each of said graphite shielding rods and each of said stainless steel rods are externally wrapped with a steel tube;

the shielding structure further comprises: grid plates arranged at the upper end and/or the lower end of the shielding structure and used for fixing the upper end part and/or the lower end part of the steel pipe,

the grid plate is basically in a closed circular ring shape or an open circular ring shape, a plurality of circles of hole sites are arranged on the grid plate, and the end part of each steel pipe is correspondingly arranged in one hole site.

11. The shielding structure of claim 1, wherein the graphite rod contains boron carbide therein.

12. A shielding assembly for a sodium-cooled fast reactor, the sodium-cooled fast reactor comprising a reactor vessel and a core disposed within the reactor vessel,

the shielding assembly includes: a radially outer shield disposed radially outwardly of the core and extending in an axial direction, wherein the radially outer shield has a shield structure according to any one of claims 1 to 11.

13. The shield assembly of claim 12 further comprising a radially inner shield disposed between the core and the radially outer shield for reflecting neutrons;

the radially inner shield is made of stainless steel; the lower part of the radial inner shield is provided with a plurality of through holes for fluid to flow.

14. The shield assembly of claim 13, wherein a lower end of the radially inner shield is substantially flush with a lower end of the radially outer shield, an upper end of the radially inner shield is higher than an upper end of the radially outer shield,

the shielding assembly further includes: a middle shield disposed above the radially outer shield, an upper end of the middle shield being higher than an upper end of the radially inner shield, the middle shield having the same structure as the radially outer shield,

the lower end part of the steel pipe of the middle shield and the upper end part of the steel pipe of the radial outer shield are installed on the same grid plate together.

15. The shield assembly of claim 14, wherein the number of turns of the shield of the radially outer shield and the shield of the central shield is 3-6 turns.

16. The barrier assembly of claim 14, the sodium-cooled fast reactor further comprising an intermediate heat exchanger disposed within the reactor vessel, wherein the barrier assembly further comprises: and the upper shield is arranged above the middle shield and used for blocking neutrons from leaking into the upper part of the middle heat exchanger from the obliquely upper part.

17. The shield assembly of claim 16, said upper shield comprising a plurality of turns of stainless steel shield, each turn of stainless steel shield consisting of a plurality of stainless steel rods surrounding a turn; the outer side of each stainless steel rod is coated with a steel pipe, and the lower end part of the upper shielded steel pipe and the upper end part of the middle shielded steel pipe are installed on the same grid plate together;

the upper shield further includes: and the grid plate is used for fixing the upper end part of the steel pipe.

18. The shielding assembly of claim 16, further comprising: the setting is in radially outer shielding with interior steel cylinder between the radial interior shielding is in with the setting the outer steel cylinder in the radial outside of upper portion shielding is used for fixed mounting radially outer shielding radially interior shielding middle part shielding and the upper portion shielding.

19. The shield assembly of claim 12, the sodium cooled fast reactor further comprising a cascade plate header disposed within the reactor vessel, wherein the shield assembly further comprises: a lower shield disposed radially outwardly of said baffle header below said radially outer shield for shielding neutrons from entering said baffle header, said lower shield having a shielding structure according to any one of claims 1 to 11.

20. The shield assembly of claim 19 wherein said lower shield defines a passage therethrough for allowing passage of pressure tubes of said sodium-cooled fast reactor; in the lower shield, the number of turns of the shield is 2 to 3.

21. The shield assembly of claim 12, further comprising a drive unit disposed within the reactor vessel for driving the flow of liquid sodium, wherein a stainless steel shield layer is disposed on a sidewall of the radially outer shield facing the drive unit for reducing neutron radiation to the drive unit.

22. A sodium-cooled fast reactor comprising a reactor vessel, a core disposed within the reactor vessel, an intermediate heat exchanger, a grid header and a drive unit for driving the flow of liquid sodium, characterized in that the sodium-cooled fast reactor further comprises a shield assembly according to any one of claims 11 to 21.

23. The sodium-cooled fast reactor according to claim 22, further comprising an in-reactor support, wherein the in-reactor support comprises an upper support plate at the upper part, a middle support plate at the middle part and a bottom support plate at the bottom; the supporting upper plate is used for supporting the driving unit and the intermediate heat exchanger; the support middle plate is used for supporting the reactor core; the supporting bottom plate is used for supporting the grid plate header; wherein

A grid plate at the upper end of the lower shield of the shielding assembly is arranged on the supporting middle plate;

a grid plate at the lower end of the lower shield of the shielding assembly is mounted on the supporting bottom plate;

the lower end of the radial inner shield of the shielding assembly is arranged on the supporting middle plate; and is

The lower end of the inner steel cylinder of the shielding assembly is installed on the supporting middle plate.

Technical Field

The invention relates to the technical field of nuclear reactors, in particular to a shielding structure and a shielding assembly for a reactor and a sodium-cooled fast reactor.

Background

The sodium-cooled fast reactor is a fast neutron reactor taking liquid sodium as a coolant, and is a reactor type which is the most mature in relative development and the most experienced in operation in a fourth generation reactor. The in-reactor shielding of the sodium-cooled fast reactor is mainly used for reducing the dosage level of neutron flux to the reactor vessel, the reactor pit and the coolant of the two loops. At present, the in-reactor shielding of the sodium-cooled fast reactor has the defects of poor shielding effect, high radiation dose and the like.

Disclosure of Invention

The first aspect of the present invention aims to provide a new shielding structure to improve the shielding effect of the shielding structure in the reactor to neutrons, aiming at the defects existing in the prior art.

The second aspect of the present invention aims to provide a shielding assembly with good shielding effect, which overcomes the drawbacks of the prior art.

A further object of the second aspect of the invention is to effectively reduce the dosage level of neutron flux to the drive unit, intermediate heat exchanger, cascade plate header, etc.

The third aspect of the invention aims to provide a sodium-cooled fast reactor with low radiation dose.

According to a first aspect of the present invention there is provided a shielding structure for a reactor, the shielding structure comprising a plurality of turns of shielding members arranged radially therealong, each turn of shielding member comprising a plurality of graphite shielding rods arranged to define a turn, wherein

Every graphite shielding stick is formed by the concatenation of many graphite rods along the axial, and the piece position of many graphite shielding sticks of radially arranging along shielding structure is not identical.

Furthermore, the abutted seam positions of the graphite shielding rods of the same ring of shielding parts are the same; the abutted seam positions of the graphite shielding rods of two adjacent circles of shielding parts are staggered mutually.

Furthermore, the abutted seam positions of the graphite shielding rods of different rings of shielding parts are staggered.

Furthermore, each graphite shielding rod is formed by splicing two graphite rods along the axial direction.

Furthermore, the splicing positions of the graphite shielding rods of the same circle of shielding parts are the same.

Furthermore, the intervals of the splicing seam positions of the graphite shielding rods of two adjacent circles of shielding pieces are the same.

Furthermore, in the two graphite rods spliced to form the graphite shielding rod, a concave hole is formed in the axial end face of one graphite rod, a boss is formed in the axial end face of the other graphite rod, and the two graphite rods are spliced together through splicing and inserting matching of the concave hole and the boss.

Furthermore, the depth of the concave hole is the same as the height of the boss, and is smaller than the distance between the splicing seam positions of the graphite shielding rods of the two adjacent circles of shielding pieces.

Further, the number of turns of the shielding member is 2 to 6.

Further, the shielding structure further includes: and a plurality of stainless steel rods which are dispersedly arranged on the inner side and the outer side of the multi-ring shielding piece.

Furthermore, the outer sides of each graphite shielding rod and each stainless steel rod are coated with steel pipes;

the shielding structure further includes: grid plates arranged at the upper end and/or the lower end of the shielding structure and used for fixing the upper end and/or the lower end of the steel pipe,

the grid plate is basically in a closed circular ring shape or an open circular ring shape, a plurality of circles of hole sites are arranged on the grid plate, and the end part of each steel pipe is correspondingly arranged in one hole site.

Further, the graphite rod contains boron carbide.

According to a second aspect of the invention, the invention provides a shielding assembly for a sodium-cooled fast reactor, the sodium-cooled fast reactor comprises a reactor vessel and a reactor core arranged in the reactor vessel,

the shielding assembly includes: and a radially outer shield disposed radially outward of the core and extending in the axial direction, wherein the radially outer shield has any one of the shield structures described above.

Further, the shield assembly also includes a radially inner shield disposed between the core and the radially outer shield for reflecting neutrons.

Further, the radially inner shield is made of stainless steel; the lower part of the radial inner shield is provided with a plurality of through holes for fluid to flow.

Further, the lower end of the radially inner shield is substantially flush with the lower end of the radially outer shield, the upper end of the radially inner shield is higher than the upper end of the radially outer shield,

the shielding assembly further includes: a middle shield disposed above the radially outer shield, the upper end of the middle shield being higher than the upper end of the radially inner shield, the middle shield having the same structure as the radially outer shield,

the lower end part of the steel pipe of the middle shield and the upper end part of the steel pipe of the radial outer shield are arranged on the same grid plate together.

Furthermore, the number of turns of the shielding parts of the radial outer shielding and the middle shielding is 3-6.

Further, the sodium-cooled fast reactor still includes the intermediate heat exchanger who sets up in the reactor container, and the shield assembly still includes: and the upper shield is arranged above the middle shield and used for blocking neutrons from leaking into the upper part of the middle heat exchanger from the obliquely upper part.

Furthermore, the upper shield comprises a plurality of circles of stainless steel shields, and each circle of stainless steel shield consists of a plurality of stainless steel rods which are encircled into a circle; the outer side of each stainless steel rod is coated with a steel pipe, and the lower end part of the upper shielded steel pipe and the upper end part of the middle shielded steel pipe are installed on the same grid plate together;

the upper shield further includes: and the grid plate is used for fixing the upper end part of the steel pipe.

Further, the shielding assembly further comprises: the inner steel cylinder is arranged between the radial outer shield and the radial inner shield, and the outer steel cylinder is arranged on the radial outer side of the upper shield and used for fixedly mounting the radial outer shield, the radial inner shield, the middle shield and the upper shield.

Further, the sodium-cooled fast reactor still includes the grid tray header of setting in piling the container, and the shielding subassembly still includes: a lower shield disposed radially outwardly of the grid header below the radially outer shield for shielding neutrons from entering the grid header, the lower shield having any of the above-described shielding configurations.

Furthermore, a channel for allowing a pressure pipe of the sodium-cooled fast reactor to pass through is formed in the lower shield; in the lower shield, the number of turns of the shield is 2 to 3.

Further, the sodium-cooled fast reactor also comprises a driving unit which is arranged in the reactor container and used for driving liquid sodium to flow, and a stainless steel shielding layer is arranged on the side wall of the radial outer side of the radial outer shielding facing the driving unit and used for reducing radiation of neutrons to the driving unit.

According to a third aspect of the invention, the invention provides a sodium-cooled fast reactor, which comprises a reactor vessel, a reactor core arranged in the reactor vessel, an intermediate heat exchanger, a grid plate header and a driving unit for driving liquid sodium to flow, and further comprises any one of the shielding assemblies.

Furthermore, the sodium-cooled fast reactor also comprises an in-reactor support, wherein the in-reactor support comprises a support upper plate positioned at the upper part, a support middle plate positioned at the middle part and a support bottom plate positioned at the bottom; a supporting upper plate for supporting the driving unit and the intermediate heat exchanger; the support middle plate is used for supporting the reactor core; the supporting bottom plate is used for supporting the grid plate header; wherein

The grid plate at the upper end of the lower shield of the shielding assembly is arranged on the supporting middle plate;

the grid plate at the lower end of the lower shield of the shielding assembly is arranged on the supporting bottom plate;

the lower end of the radial inner shield of the shielding assembly is arranged on the supporting middle plate; and is

The lower end of the inner steel cylinder of the shielding assembly is arranged on the supporting middle plate.

In the related art of the shielding structure using graphite rod splicing, it is generally considered that the more the number of turns of the graphite shielding rod is, the better the shielding effect on neutrons is. However, the inventors of the present application have found that when the number of turns of the graphite shielding rod is increased to a certain number and the number of turns of the graphite shielding rod is further increased, the absorption effect on neutrons is not significantly increased. The inventor of the present application has further found, through research, that in the related art, for convenience of processing and convenience of installation, the positions of the seams of all graphite rods in the shielding structure are the same, and therefore neutrons can escape outwards through the positions of the seams. The inventors of the present application are making improvements to the related art based on this.

By applying the technical scheme of the invention, the splicing positions of the graphite shielding rods which are arranged along the radial direction of the shielding structure are not completely the same, and the splicing positions of at least part of the graphite shielding rods which are arranged along the radial direction of the shielding structure are allowed to be staggered, so that the outward escape of partial neutrons from the splicing positions of the graphite rods can be reduced, and the dosage level of the stack body is reduced. Furthermore, the splicing positions of the graphite shielding rods of the same circle of shielding parts are arranged to be the same, and the splicing positions of the graphite shielding rods of two adjacent circles of shielding parts are staggered mutually, so that neutrons are further reduced from escaping outwards through the splicing positions of the graphite rods, and the dosage level of the reactor body is further reduced. Furthermore, the splicing positions of the graphite shielding rods of different rings of shielding parts are staggered mutually, the intervals between the splicing positions of the graphite shielding rods of two adjacent rings of shielding parts are the same, and the splicing positions of the graphite shielding rods of all layers are staggered uniformly, so that the dosage level can be reduced remarkably.

By applying the technical scheme of the invention, the overall structure of the shielding assembly is reasonably arranged, and the dosage level of neutron flux on a reactor vessel, a reactor pit, a driving unit, an intermediate heat exchanger, a grid plate header, a secondary circuit coolant and an accident waste heat discharge coolant can be effectively reduced.

Drawings

Other objects and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings, and may assist in a comprehensive understanding of the invention.

FIG. 1 is a schematic block diagram of a shielding structure according to an embodiment of the present invention;

FIG. 2 is an enlarged view at A of FIG. 1;

FIG. 3 is a schematic top view of the shielding structure of FIG. 1;

FIG. 4 is an enlarged view of the grid plate at B in FIG. 3;

FIG. 5 is an enlarged view at C of FIG. 3, schematically illustrating the multi-turn shield of the shield arrangement;

FIG. 6 schematically illustrates the patchwork position of the multi-turn shield shown in FIG. 5;

FIG. 7 is a schematic structural diagram of a sodium-cooled fast reactor according to an embodiment of the invention;

FIG. 8 is a cross-sectional view of a shield assembly according to an embodiment of the present invention;

FIG. 9 is an enlarged view at D of FIG. 8;

FIG. 10 is an enlarged view at E of FIG. 8;

FIG. 11 is an enlarged view at F of FIG. 8;

fig. 12 is an installation schematic of a shield assembly according to an embodiment of the invention.

It is noted that the drawings are not necessarily to scale and are merely illustrative in nature and not intended to obscure the reader.

Description of reference numerals:

1. a reactor; 10. a shielding assembly; 100. a shielding structure; 101. a radially outer shield; 102. a radially inner shield 102; 103. shielding the middle part; 104. an upper shield; 105. a lower shield; 1051. a channel; 1052. a shielding steel plate; 106. an inner steel cylinder; 107. an outer steel cylinder; 11. a graphite shielding rod; 111. a first ring of shields; 112. a second turn of shielding; 113. a third turn of shielding; 114. a fourth turn of shielding; 115. a fifth turn of shielding; 12. a graphite rod; 13. a steel pipe; 131. a steel ring; 132. a bolt; 14. a stainless steel rod; 15. a grid plate; 151. hole site; 152. a support leg; 16. a through hole; 20. a stack container; 30. a core; 40. an intermediate heat exchanger; 50. a grid plate header; 60. a drive unit; 70. in-pile support; 71. supporting the upper plate; 72. a support middle plate; 73. a support floor; 90. and a stainless steel shielding layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention. It should be apparent that the described embodiment is one embodiment of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.

It is to be noted that technical terms or scientific terms used herein should have the ordinary meaning as understood by those having ordinary skill in the art to which the present invention belongs, unless otherwise defined. Spatially relative terms, such as "above," "below," "upper," "lower," and the like, may be used herein for ease of description to describe only the spatial relationship of one component or feature to another component or feature as illustrated in the figures, and should be understood to encompass different orientations in use or operation in addition to the orientation depicted in the figures.

The shielding structure provided by the embodiment of the invention is suitable for being applied to a reactor, particularly a sodium-cooled fast reactor, and is used as an in-reactor shielding structure for shielding neutrons.

As shown in fig. 1 to 6, the shielding structure of the embodiment of the present invention includes a plurality of turns of shielding members arranged along a radial direction thereof, and each turn of shielding member is composed of a plurality of graphite shielding rods 11 surrounding one turn.

Referring to fig. 1 and 3, in this embodiment, since the installation position of the shielding structure 100 interferes with the reactor internals, which need to be set aside, the shielding structure 100 is configured in a ring shape having an opening. Accordingly, the graphite shielding rods 11 of each shield turn substantially enclose an annular shape with an opening. Of course, the shielding structure 100 may be configured in a substantially closed circular ring shape when the installation position of the shielding structure 100 does not interfere with the reactor internals.

As will be readily understood by those skilled in the art, for two adjacent turns of the shield, the graphite shielding rod 11 located at the outer turn of the shield is preferably disposed between two adjacent graphite shielding rods 11 located at the inner turn of the shield to close the gap between the two graphite shielding rods 11 at the inner turn, thereby better shielding neutrons. In some cases, the shield may not necessarily enclose a continuous ring, may enclose multiple discontinuous, broken arcs, or may simply be dispersed at multiple points outside the shield of the next outer turn (see shield 115 in fig. 5), where the line of the discontinuous arcs or dispersed points may generally form a ring.

In the embodiment shown in fig. 5 and 6, the shielding structure 100 is divided into 5 turns of shielding members in the radial direction thereof, namely, a shielding member 111 (the innermost turn or the first turn), a shielding member 112 (the second turn), a shielding member 113 (the third turn), a shielding member 114 (the fourth turn), and a shielding member 115 (the outermost turn or the fifth turn).

It should be noted that in some embodiments, since the graphite shielding rods 11 are not arranged in a standard circular ring by one turn, it may be inconvenient to divide the shielding members by turns in some cases. In such an embodiment, to facilitate dividing the turns of the shield, the division may be performed as follows: the plurality of graphite shielding rods 11 arranged along the radial direction of the shielding structure 100, from the inside to the outside, the graphite shielding rods 11 sequentially belong to a first circle, a second circle, a third circle, a fourth circle and the like.

In some cases, if the circle to which the graphite shielding rod 11 belongs is divided in the above dividing manner, and a certain graphite shielding rod 11 belongs to two circles along the radial direction of different angles of the shielding structure 100, which circle of shielding member the graphite shielding rod 11 belongs to can be determined according to the following method. The plurality of graphite shielding bars 11 in the radial direction of the shielding structure 100 passing through the axis of the graphite shielding bar 11 (i.e., the graphite shielding bar 11 to which the turn of the shielding member is to be determined) belong to a first turn, a second turn, a third turn, a fourth turn, and the like in this order from the inside to the outside. For example, the shield structure 100 has 5 steel pipes 13 in total in a radial direction S passing through the axis of the graphite shield rod 11 with respect to the graphite shield rod 11 indicated by an arrow in fig. 5. Wherein, the stainless steel bar 14 is wrapped in the first steel tube 13 from inside to outside, the arrangement and the function of which are described in detail below, the steel tube 13 wrapped with the stainless steel bar 14 does not belong to any ring of shielding members. The graphite shielding rod 11 wrapped by the second steel pipe 13 belongs to the first shielding ring 111, the graphite shielding rod 11 wrapped by the third steel pipe 13 belongs to the second shielding ring 112, the graphite shielding rod 11 wrapped by the fourth steel pipe 13 belongs to the third shielding ring 113, and the graphite shielding rod 11 wrapped by the fifth steel pipe 13 (i.e. the steel pipe 13 indicated by the arrow in the figure) belongs to the fourth shielding ring 114.

The present application does not limit the dividing method of each shield, and each shield may be divided by other methods. In the present invention, there may be some graphite shielding rods 11 which are not easily divided, which does not affect the overall technical solution for implementing the present invention, and therefore, in some embodiments, it may be arbitrarily designated which circle it belongs to.

In the shielding structure 100 of the embodiment of the present invention, each graphite shielding rod 11 enclosing the shielding member is formed by splicing two graphite rods 12 in the axial direction. In the present embodiment, the graphite rod 12 is a boron carbide-containing graphite rod, referred to as boron-containing graphite rod for short. Because the graphite shielding rod 11 is longer and is limited by the production length of the boron-containing graphite rod, the graphite shielding rod 11 which is enclosed into the shielding part needs to be assembled in a splicing mode by adopting two graphite rods 12 in length, and the length requirement of the shielding part can be met. In the related art, in order to facilitate processing and installation, each graphite shielding rod 11 is formed by splicing two graphite rods 12 in the axial direction, and the splicing positions of all the graphite rods 12 in the shielding structure 100 are the same. However, the inventors of the present application have found that with the shield structure 100 thus configured, neutrons can escape outward via the patchwork locations. The inventors of the present application are making improvements to the related art based on this.

In particular, in the embodiment of the present invention, the positions of the seams of the plurality of graphite shielding rods 11 arranged in the radial direction of the shielding structure 100 are set to be not completely the same. That is, the axial projections of all the seam positions of the graphite shielding rods 11 arranged along the radial direction of the shielding structure 100 are not completely overlapped, and the projections of the seam positions are at least two. Alternatively, the positions of the seams of the plurality of graphite shielding rods 11 arranged in the radial direction of the shielding structure 100 are set to be at least partially the same. Therefore, partial neutrons can be reduced from escaping outwards through the splicing positions of the graphite rods 12, and the dosage level of the stack body is reduced.

For the convenience of processing, the splicing positions of the graphite shielding rods 11 of the same circle of shielding parts are the same. In some embodiments, the seam positions of the graphite shielding rods 11 of two adjacent turns of shielding members are staggered from each other. That is, in the plurality of graphite shielding rods 11 arranged in the radial direction of the shielding structure 100, the positions of the seams of two adjacent graphite shielding rods 11 are staggered from each other, so as to reduce the outward escape of neutrons through the positions of the seams of the graphite rods 12.

In a further embodiment, the splicing positions of the graphite shielding rods 11 of different shielding rings are all staggered with respect to each other, or the splicing positions of a plurality of graphite shielding rods 11 arranged along the radial direction of the shielding structure 100 are all staggered with respect to each other. This also means that the axial projections of all the patchwork positions of the graphite shielding rods 11 arranged in the radial direction of the shielding structure 100 do not coincide. Thus, neutrons are less likely to escape outward from the patchwork locations, and dosage levels can be significantly reduced. In a further embodiment, the intervals between the seam positions of the graphite shielding rods 11 of two adjacent turns of shielding members are the same, so that the seam positions of the graphite shielding rods 11 of each layer can be uniformly staggered. The shielding structure 100 designed according to the method can reduce neutron escape to the maximum extent, has better shielding effect, and further reduces the dosage level of the stack body.

Fig. 6 shows the position of the seams of the graphite shielding rods 11 in the first, second, third, fourth and fifth turns of shielding 111, 112, 113, 114, 115. The distance h between the abutted seam positions of the graphite shielding rods 11 of two adjacent circles of shielding parts₁Are all the same. In some embodiments, the distance h between the splicing positions of the graphite shielding rods 11 of two adjacent turns of shielding pieces₁Can be set to be 20 cm-50 cm; it may be further set to 30cm to 40cm, for example, 40 mm. In other embodiments, the spacing h₁May also be determined approximately according to the number of turns n of the shielding structure 100, for example, the position of the seam of each turn of the shielding rod may be located at (n +1) times the length of the graphite shielding rod 11. The design scheme of the staggered abutted seam of the graphite rod 12 can effectively resistThe stop neutron escapes from the abutted seam, the production and the assembly of the graphite rod 12 are facilitated, and the installation efficiency can be effectively improved.

In some embodiments, referring to fig. 6, in the two graphite rods 12 spliced to form the graphite shielding rod 11, one graphite rod 12 is provided with a concave hole at an axial end face, and the other graphite rod 12 is provided with a convex block at an axial end face, and the two graphite rods 12 are spliced together through the splicing fit of the concave hole and the convex block. The concave hole and the boss can be in clearance fit. Depth of concave hole and height h of boss₂The same distance h is smaller than the joint position of the graphite shielding rods 11 of two adjacent circles of shielding parts₁Thereby further hindering neutron escape. Tests show that the splicing mode can be reliably connected and can not be disconnected in the processes of manufacturing, transportation, assembly, normal operation and the like.

It should be noted that the splicing manner of the graphite rods 12 is not limited to this, and in other embodiments not shown in the drawings, other splicing schemes may be adopted for the two graphite rods 12. In addition, because the splicing positions of the graphite shielding rods 11 of different rings are staggered, the shielding effect of splicing the plurality of graphite rods 12 is equivalent to or even better than the shielding effect of splicing only two graphite rods 12 in the related art, and therefore each graphite shielding rod 11 can be formed by splicing three or more graphite rods 12 in the axial direction. Since the length of the graphite rod 12 is not required for the splicing of the plurality of graphite rods, the graphite rod 12 can be used properly, and even a short graphite rod 12 can be used without waste.

In the embodiment of the invention, the number of turns of the shielding members in the shielding structure 100 can be selected from 2 to 6, and the number of turns of the shielding members can be reasonably selected according to the shielding requirements of different positions in the reactor. When the shield structure 100 is used on the radially outer side of the core, the number of turns of the shield may be set to be larger, for example, 4 turns, 5 turns, or 6 turns, because neutrons are more. When the shielding structure 100 is used on the radially outer side of the cascade plate header, the number of turns of the shielding member can be set to be smaller, for example, 2 or 3 turns, because neutrons are relatively fewer.

For the convenience of assembly, the outer side of each graphite shielding rod 11 is coated with a steel pipe 13. Accordingly, the shielding structure 100 may further include two grid plates 15 for fixing the upper and lower ends of the steel pipes 13, respectively, so as to assemble the graphite shielding rods 11 together to form the unitary shielding structure 100. Referring to fig. 3 and 4, since the installation position of the shielding structure 100 interferes with the reactor internals, which need to be set aside, the grid plate 15 is configured in a ring shape having an opening. Of course, in other embodiments, the grid plate 15 may be configured in a substantially closed circular ring shape without interference of the installation position of the shielding structure 100 with the reactor internals.

Referring to fig. 3 and 4, the grid plate 15 is provided with a plurality of circles of hole sites 151, and the end of each steel tube 13 is correspondingly installed in one hole site 151. The holes 151 are mostly distributed in a regular triangle, so that the graphite shielding rods 11 located in the outer shielding member can close the gap between the two graphite shielding rods 11 in the inner shielding member.

The shielding structure 100 may further include a plurality of stainless steel rods 14 dispersedly disposed inside the innermost circumference shield and outside the outermost circumference shield. Referring to fig. 6, a plurality of stainless steel rods 14 are dispersedly disposed on the radially inner side of the first ring of shields 111, and a plurality of stainless steel rods 14 are dispersedly disposed on the radially outer side of the fifth ring of shields 115. For the convenience of installation, the outer side of each stainless steel bar 14 is also covered with a steel tube 13, and the end of the steel tube 13 is also correspondingly installed in one hole 151 of the grid plate 15.

In the embodiment of the present invention, although the graphite rods 12 and the stainless steel rods 14 are wrapped in the steel tube 13, since the reaction cross section of the steel tube 13 is small, the neutrons reflected by the steel tube 13 are limited, and most of the neutrons pass through the steel tube 13 and then contact the graphite rods 12 or the stainless steel rods 14 inside the steel tube 13. The stainless steel rods 14 mainly serve to reflect neutrons (collisions between the stainless steel rods 14 and neutrons, if elastic, macroscopically, neutrons are reflected; if inelastic, neutrons lose part of energy and have a slower speed). The graphite rod 12 acts to moderate neutrons; that is, the energy of neutrons is reduced and the speed is lowered. The smaller the neutron energy, the more likely it is for the desired and monitor controlled reaction to occur, so the presence of graphite rod 12 is more conducive to neutron monitoring. And the smaller the neutron energy is, the more difficult the neutron energy is to escape outwards, the neutron leakage can be reduced, and the service efficiency of the reactor core neutrons is improved.

Based on the shielding structure 100 of any of the foregoing embodiments, the present invention may also provide a shielding assembly for a sodium-cooled fast reactor. Referring to fig. 7, the sodium-cooled fast reactor 1 may include a reactor vessel 20, a core 30 disposed in the reactor vessel 20, an intermediate heat exchanger 40, a cascade plate header 50, and a driving unit 60 for driving the flow of liquid sodium.

Referring to fig. 8 to 11, the shielding assembly 10 may include: and a radially outer shield 101 disposed radially outwardly of the core 30 and extending in the axial direction. The radially outer shield 101 has a shield structure 100 as shown in fig. 1. In the embodiment of the present invention, because the seam positions of the graphite shielding rods 11 arranged in the radial direction of the radially outer shield 101 are set to be not completely the same, the seam positions of at least part of the graphite shielding rods 11 arranged in the radial direction of the radially outer shield 101 are allowed to be staggered from each other, so that it is possible to reduce the number of partial neutrons escaping outwards through the seam positions of the graphite rods 12, and to reduce the dosage level of the stack body.

In some embodiments, the shield assembly 10 may also include a radially inner shield 102 disposed between the core 30 and the radially outer shield 101 for reflecting neutrons. The radially inner shield 102 is a radial first pass shield located outside the core shroud. The radially inner shield 102 may be made of stainless steel. In the embodiment shown in the figures, the radially inner shield 102 is tailored by welding a plurality of layers of stainless steel sheet coils into a concentric sleeve. The radially inner shield 102 has a plurality of through holes 16 formed in a lower portion thereof for fluid flow.

The radially outer shield 101 and the radially inner shield 102 together form a radiation-blocking shield in the radial direction, and play a role in ensuring the maximum neutron fluence rate in the intermediate heat exchanger 40. Depending on the neutron detection requirements of the in-stack ionization chamber and the out-of-stack detector, it may be desirable to open a hole in the radially inner shield 102 and place the radially outer shield 101 in an open configuration as shown in fig. 1 and 3.

Referring to fig. 7 and 8, on a side wall facing the driving unit 60 on a radially outer side of the radially outer shield 101, a stainless steel shield layer 90 is provided for reducing radiation of neutrons to the driving unit 60.

As shown in fig. 7, the lower end of the radially inner shield 102 is substantially flush with the lower end of the radially outer shield 101, both lower than the lower end of the core 30; the upper end of the radially inner shield 102 is higher than the upper end of the core 30; the upper end of the radially inner shield 102 is higher than the upper end of the radially outer shield 101.

The shielding assembly 10 further includes: a middle shield 103 disposed above the radially outer shield 101, an upper end of the middle shield 103 being higher than an upper end of the radially inner shield 102. The middle shield 103 has the same structure as the radially outer shield 101, and the lower end portion of the steel pipe 13 of the middle shield 103 and the upper end portion of the steel pipe 13 of the radially outer shield 101 are mounted together on the same grid plate 15, see fig. 10. It will be understood by those skilled in the art that the radially outer shield 101 and the middle shield 103 could theoretically be provided integrally, and the middle shield 103 is an extension of the radially outer shield 101, but the radially outer shield 101 and the middle shield 103 are provided separately due to the limitations of the manufacturing process. The number of turns of the shield of the radially outer shield 101 and the central shield 103 may be 3-6 turns, such as 4 or 5 turns. Those skilled in the art will readily appreciate that the radially outer shield 101 and the central shield 103 may be similar or identical in construction, but may be different in height.

Referring to fig. 7 and 8, the shield assembly 10 may further include an upper shield 104 disposed above the middle shield 103 for blocking neutrons from leaking obliquely above into the upper portions of the intermediate heat exchanger 40 and the separate heat exchangers, acting to reduce secondary sodium activity.

In some embodiments, referring to fig. 8 and 9, the upper shield 104 may comprise a plurality of turns of stainless steel shield, each turn consisting of a plurality of stainless steel rods 14 surrounding a turn. The outer side of each stainless steel rod 14 is covered with a steel pipe 13, and the lower end part of the steel pipe 13 of the upper shield 104 and the upper end part of the steel pipe 13 of the middle shield 103 are installed on the same grid plate 15 together. The upper shield 104 further includes a grid plate 15 for fixing the upper end of the steel pipe 13 thereof.

In some embodiments, the shielding assembly 10 further comprises: an inner steel cylinder 106 disposed between the radially outer shield 101 and the radially inner shield 102, and an outer steel cylinder 107 disposed radially outside the upper shield 104 for fixedly mounting the radially outer shield 101, the radially inner shield 102, the middle shield 103, and the upper shield 104.

The upper end of the inner steel cylinder 106 is substantially flush with the upper end of the middle shield 103, the lower end of the inner steel cylinder is substantially flush with the lower end of the radial outer shield 101, and a plurality of through holes 16 for fluid to flow are formed in the side wall of the inner steel cylinder 106 higher than the radial inner shield 102. The upper end of the outer steel cylinder 107 is substantially flush with the upper end of the upper shield 104 and the lower end is lower than the upper end of the radially inner shield 102.

The grid plate 15 at the upper end of the upper shield 104 is mounted on the upper edge of the outer steel cylinder 107. The radially inner side of the grid plate 15 shared by the upper shield 104 and the middle shield 103 is mounted on the upper edge of the inner steel cylinder 106, and the radially outer side of the grid plate 15 is mounted on the middle-lower portion of the outer steel cylinder 107. The radially inner side of the grid plate 15 shared by the radially outer shield 101 and the central shield 103 is mounted in the middle of the inner steel cylinder 106. The radially inner side of the grid plate 15 of the lower end of the radially outer shield 101 is mounted at the lower end of the inner steel cylinder 106.

The method for mounting the upper and lower shield structures will be briefly described below by taking the middle shield 103 and the upper shield 104 as examples. Referring to fig. 12, one end of the steel pipe 13 is provided with a receiving groove, a steel ring 131 fixed by a bolt 132 is arranged in the receiving groove, and the other end of the steel pipe is provided with a protrusion structure, and the protrusion structure is provided with a threaded hole. The receiving groove at the lower end of the upper steel pipe 13 extends downwards into one hole 151 of the grid plate 15, the protruding structure at the upper end of the lower steel pipe 13 extends into the receiving groove, and the upper steel pipe 13 and the lower steel pipe are mounted on the same hole 151 of the middle grid plate 15 through the matching of the bolt 132 and the thread. The grid plate 15 is used for load bearing and is secured to the inner steel cylinder 106 by legs 152. Specifically, the supporting legs 152 are welded to the inner steel cylinder 106, and the grid plate 15 is fixed by slotted screws, and the slotted screws and bolts are fixed by spot-welding. The assembling manner of each shielding structure is similar, and is not described herein.

In some embodiments, the shielding assembly 10 may further include: a lower shield 105 disposed radially outwardly of the header 50 below the radially outer shield 101 for shielding neutrons from entering the header 50, the lower shield 105 may have the shielding structure 100 of any of the previously described embodiments. In the lower shield 105, the number of turns of the shield may be 2 to 3 turns.

The lower shield 105 is provided with a plurality of channels 1051 for allowing the pressure tubes of the sodium-cooled fast reactor 1 to pass through. In order to facilitate the opening of the passage 1051, the lower shield 105 is provided with a shield steel plate 1052 instead of the stainless steel rod 14 or the graphite shield rod 11 at the position where the passage 1051 is provided. The lower shield 105 may be disposed in a lower support of the in-stack support 70.

Based on the shielding assembly 10 of any one of the embodiments, the invention further provides a sodium-cooled fast reactor. Referring to fig. 7, the sodium-cooled fast reactor 1 includes a reactor vessel 20, a core 30 disposed in the reactor vessel 20, an intermediate heat exchanger 40, a cascade plate header 50, and a driving unit 60 for driving the flow of liquid sodium. The sodium-cooled fast reactor 1 further comprises a shielding assembly 10 in any one of the embodiments.

Referring to fig. 7, the in-stack shield is divided into two parts, a core-surrounding shield and a grid plate header-surrounding shield, according to the position and function of the shield structure 100: the core periphery shield includes a radially outer shield 101, a radially inner shield 102, a middle shield 103, and an upper shield 104; the grid header surrounding shield includes a lower shield 105. The shielding around the reactor core penetrates through the in-reactor ionization chamber channel, the sodium level meter and the thermocouple, and the in-reactor ionization chamber cooling channel, the sodium level meter channel and the thermocouple channel can be arranged on the corresponding shielding structure according to the requirement.

In the illustrated embodiment, the sodium-cooled fast reactor 1 further comprises an in-reactor support 70, and the in-reactor support 70 comprises an upper support plate 71 at the upper part, a middle support plate 72 at the middle part and a bottom support plate 73 at the bottom part. The supporting upper plate 71 for supporting the driving unit 60 and the intermediate heat exchanger 40; the support middle plate 72 is used for supporting the core 30; the support floor 73 serves to support the header 50. The grid plate 15 at the upper end of the lower shield 105 may be mounted on the support middle plate 72; the grid plate 15 at the lower end of the lower shield 105 may be mounted on the support floor 73; the lower end of the radially inner shield 102 may be mounted on the support mid-plate 72; the lower end of the inner steel cylinder 106 may be mounted on the support mid-plate 72.

In an alternative embodiment, the lower end of the steel tube 13 of the radially inner shield 102 is mounted on the same grid plate 15 together with the upper end of the steel tube 13 of the lower shield 105.

The sodium-cooled fast reactor 1 of the embodiment of the invention has the advantages that the overall structure of the shielding assembly 10 is reasonably arranged, and the seam positions of the graphite shielding rods 11 are carefully designed, so that the dosage levels of neutron flux to a reactor container, a reactor pit and a secondary loop coolant can be effectively reduced, neutrons are prevented from escaping from the seam positions, and the installation efficiency can be effectively improved.

It should also be noted that, in the case of the embodiments of the present invention, features of the embodiments and examples may be combined with each other to obtain a new embodiment without conflict.

The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and the scope of the present invention is subject to the scope of the claims.