CN113921155A

CN113921155A - Critical experimental device for spent fuel

Info

Publication number: CN113921155A
Application number: CN202111389063.7A
Authority: CN
Inventors: 陈善发; 陈效先; 夏兆东; 周琦; 成昱廷; 李开健; 章秩烽; 徐健平; 吕牛
Original assignee: China Institute of Atomic of Energy
Current assignee: China Institute of Atomic of Energy
Priority date: 2021-11-22
Filing date: 2021-11-22
Publication date: 2022-01-11
Anticipated expiration: 2041-11-22
Also published as: CN113921155B

Abstract

The embodiment of the invention discloses a critical experimental device of spent fuel, which comprises: the reactor core comprises a reactor core container, wherein the bottom of the reactor core container is provided with a guide hole; the guide pipe is fixed at the guide hole in the reactor core container, the guide pipe is used for placing the spent fuel, and the guide hole is used for providing a hole channel for the input and the output of the spent fuel; a plurality of mounting units arranged in an array around the guide pipe in the core vessel, the mounting units being used for mounting new fuel elements; wherein the top end of the guide tube is closed for isolating the aqueous environment of the new fuel element. The embodiment of the invention adopts a mode of combining part of spent fuel and part of new fuel to develop a spent fuel critical experiment, and a closed guide pipe is arranged on a spent fuel critical experiment device and is specially used for temporarily storing the spent fuel to isolate the spent fuel from the water environment of the new fuel so as to avoid radioactive pollution.

Description

Critical experimental device for spent fuel

Technical Field

The embodiment of the invention relates to the technical field of spent fuel post-treatment, in particular to a critical experimental device for spent fuel.

Background

In the aspect of spent fuel aftertreatment, because the existing spent fuel aftertreatment has low efficiency, only the spent fuel which is not treated in time can be stored, so that the most extensive countermeasure at the present stage is to store the spent fuel. However, due to the lack of critical experimental data of the spent fuel, the effectiveness and accuracy of the critical calculation program for the spent fuel remain to be verified, so that most storage methods of the spent fuel are still stored according to the standard of new fuel, which greatly increases the storage cost of the spent fuel. Therefore, a critical experimental device for performing the experiment of the reactivity effect of the spent fuel is needed.

Disclosure of Invention

The embodiment of the invention provides a critical experimental device of spent fuel, which comprises: the reactor core comprises a reactor core container, wherein the bottom of the reactor core container is provided with a guide hole; the guide pipe is fixed at the guide hole in the reactor core container, the guide pipe is used for placing the spent fuel, and the guide hole is used for providing a hole channel for the input and the output of the spent fuel; a plurality of mounting units arranged in an array around the guide pipe in the core vessel, the mounting units being used for mounting new fuel elements; wherein the top end of the guide tube is closed for isolating the aqueous environment of the new fuel element.

Drawings

Other objects and advantages of the present invention will become apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, and may help to provide a full understanding of the present invention.

Fig. 1 is a schematic structural diagram of a critical experimental apparatus for spent fuel according to an embodiment of the present invention.

Fig. 2 is a top view of the apparatus for critical testing of spent fuel of fig. 1.

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:

100. spent fuel; 10. a core vessel; 11. a guide hole;

200. a new fuel element; 20. a guide tube;

30. a mounting unit; 31. a first grid plate; 32. a second grid plate; 33. a support pillar;

40. a support portion; 41. a base plate; 42. a floor support.

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. If the description "first", "second", etc. is referred to throughout, the description of "first", "second", etc. is used only for distinguishing similar objects, and is not to be construed as indicating or implying a relative importance, order or number of technical features indicated, it being understood that the data described in "first", "second", etc. may be interchanged where appropriate. If "and/or" is presented throughout, it is meant to include three juxtapositions, exemplified by "A and/or B" and including either scheme A, or scheme B, or schemes in which both A and B are satisfied. Furthermore, spatially relative terms, such as "above," "below," "top," "bottom," and the like, may be used herein for ease of description to describe one element or feature's spatial relationship to another element 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.

Fig. 1 is a schematic structural diagram illustrating a critical experimental apparatus for spent fuel according to an embodiment of the present invention. Fig. 2 shows a top view of the apparatus for critical testing of spent fuel of fig. 1. As shown in fig. 1 and 2, the critical experimental apparatus for spent fuel in the present embodiment includes a core vessel 10, a guide pipe 20, and a plurality of installation units 30. The bottom of the reactor core vessel 10 is provided with a guide hole 11, a guide pipe 20 is fixed in the reactor core vessel 10 at the guide hole 11, and the guide pipe 20 is used for placing the spent fuel 100. A plurality of installation units 30 are arranged in an array around the guide pipe 20 in the core vessel 10, and the installation units 30 are used for installing new fuel elements 200. Wherein the top end of the guide tube 20 is closed for isolating the aqueous environment of the new fuel element 200.

The critical experiment device in the embodiment can be used for developing the critical experiment of the spent fuel in a mode of combining part of spent fuel and part of new fuel. The moderator (for example, water) is injected into the reactor core container, so that the condition that the spent fuel is stored in the water pool can be simulated, and the top end of the guide pipe 20 is closed, so that the spent fuel can be isolated from the water environment of the fresh fuel, and the radioactive pollution of the spent fuel with stronger radioactivity to the experimental environment and even the safety of personnel can be endangered. By using the critical experiment device provided by the embodiment of the invention, the situation that the spent fuel is stored in the pool can be simulated, the critical experiment can be carried out on the spent fuel, and support data is provided for the storage of the spent fuel.

In some embodiments, the lower ports of the guide tubes 20 are located at the lower portion of the core vessel 10 and are matched and communicated with the guide holes 11 to perform the input and output operations of the spent fuel 100 from below the core vessel 10. In this embodiment, the spent fuel 100 can be transported into the guide tube 20 through the guide hole 11 at the bottom of the reactor core container 10, and the guide tube 20 can be used for temporarily storing a spent fuel sample, and can also guide the spent fuel when the spent fuel sample is input into the reactor core container 10, so that the spent fuel is installed at a preset position in the reactor core container 10.

Alternatively, the mounting units 30 for mounting the new fuel elements 200 may be arranged in a 3 × 3 array, with the unit at the center of the 3 × 3 array being left free, and the mounting unit 30 not being provided, and the guide tube 20 being provided at this position, so that the guide tube 20 and 8 mounting units together form a 3 × 3 array. By adopting the arrangement, the new fuel elements 200 can be arranged around the spent fuel 100, so that the new fuel has certain symmetry, and the 3 x 3 array arrangement can make the experimental device more compact, thereby reducing the loading capacity of the new fuel elements on the premise of completing the experiment.

In the present embodiment, a plurality of new fuel elements 200 may be provided on each mounting unit 30. A plurality of the new fuel elements 200 are arranged on the mounting unit 30 in an array, thereby forming a new fuel assembly. For example, for a new fuel element with a low enrichment (e.g., 4.95%), 81 new fuel elements 200 may be arranged in a 9 × 9 array on the mounting unit 30 to form a new fuel assembly. And 8 new fuel assemblies and spent fuel are arranged according to a 3 x 3 array.

In the embodiment, the installation units divide the new fuel elements into the new fuel assemblies, so that the situation that spent fuel is stored in the pool can be simulated. In the embodiment, the reactor core arrangement is carried out by arranging the new fuel elements and the spent fuel in the arrangement mode, so that the critical experiment of the arrangement of various reactor cores with various enrichment degrees can be realized, and the critical state is achieved by controlling the number of the fuel elements in the number of the loaded new fuel assemblies during the experiment.

In some embodiments, the position of each of the mounting units 30 is selectively movable therebetween. The position of the mounting unit 30 loaded with new fuel elements can be moved so that a moderated zone can be formed between each new fuel assembly. Alternatively, the width of the moderating zone may be adjusted by moving the mounting units 30 to change the spacing between the mounting units 30 to create a different spacing between new fuel assemblies.

As shown in fig. 1 and 2, the critical testing apparatus in the present embodiment further includes a support portion 40, the support portion 40 is disposed at the bottom of the core vessel 10, and the support portion 40 is disposed around the guide pipe 20; each of the mounting units 30 is movably coupled to the supporting part 40. In some embodiments, the support portion 40 is fixed to the bottom of the core vessel 10 to support each installation unit 30.

Further, the support portion 40 includes a bottom plate 41 and a bottom plate support 42, the mounting unit is movably coupled to the bottom plate 41, the bottom plate support 42 is fixed to the bottom of the core vessel 10, and the bottom plate 41 is coupled to the bottom plate support 42. Alternatively, the base plate support 42 is a column, and the base plate is fixed to the column-shaped base plate support 42, so that a plurality of mounting units 30 can be mounted on a flat base plate.

Wherein, the support portion 40 is disposed around the guide tube 20, and specifically includes: the base plate 41 surrounds the guide tube 20. Specifically, the bottom plate 41 is provided with through holes matched with the guide tubes 20 at positions corresponding to the positions of the guide tubes 20, through which the guide tubes 20 pass and are fixed in the core vessel 10.

In some embodiments, the mounting unit 30 is provided with at least one sliding portion (not shown), the supporting portion 40 is provided with a plurality of sliding rails (not shown) arranged perpendicular to each other, and the sliding portion is matched with the sliding rails so that the mounting unit 30 is slidably connected to the supporting portion 40, thereby realizing the movement of each mounting unit 30 on the supporting portion 40.

Specifically, the slide rails may be provided on the bottom plate 41, and in addition, a plurality of slide rails may be arranged on the bottom plate 41 in a grid shape perpendicular to each other, so that the mounting unit 30 may be moved to any position on the bottom plate 41. In addition, the sliding part may be a universal wheel, and at least one universal wheel is disposed at the bottom of the mounting unit 30, for example, a universal wheel is disposed at each of four corners of the bottom of the mounting unit 30, and the universal wheels may be embedded into the sliding rails on the supporting part 40, so that the mounting unit can be moved by the cooperation of the universal wheels and the sliding rails.

Further, the critical experiment apparatus in this embodiment further includes a fixing member (not shown in the figure), which is disposed on the supporting portion 40 or the mounting unit 30, and is used for fixing the mounting unit 30 on the supporting portion 40. For example, a fixing member may be provided on the bottom plate 41 at a position close to the slide rail, or a fixing member may be provided at a position close to the sliding portion at the bottom of the mounting unit 30, and the mounting unit 30 may be fixed at the position by the fixing member after the mounting unit 30 is moved to a suitable position, so as to prevent the mounting unit 30 from sliding during the experiment. Here, the fixing member may be any member for fixing the sliding portion of the mounting unit 30, for example, a bolt, a stopper, and the like.

As shown in fig. 1, in the present embodiment, the mounting unit 30 includes a first grid plate 31, a second grid plate 32, and a support column 33. The first grid plate 31 is movably connected to the support part 40, for example, a sliding part is provided on the lower surface of the first grid plate, so that the sliding part is matched with a slide rail provided on the support part 40 to realize the movement of the first grid plate 31. The support columns 33 are connected at both ends to the first and

second grid plates

31 and 32, respectively, and the support columns 33 may be used to support the second grid plate 32. The new fuel elements 200 are installed between the first and

second grid plates

31 and 32. In other embodiments, the new fuel element 200 may also be mounted on the first grid plate 31 and pass through the second grid plate 32, and the second grid plate 32 is located at a position higher than the middle of the new fuel element 200. Wherein, a plurality of grids are arranged on the first grid plate 31 and the second grid plate 32, and each new fuel element 200 is respectively arranged in the grids.

Further, the grids on the first and

second grid plates

31 and 32 are arranged in an array, so that the new fuel elements can be arranged in an array on the first and

second grid plates

31 and 32.

In this embodiment, the new fuel elements 200 are limited by the second grid plate 32, so that the new fuel elements 200 can be prevented from being inclined only by being arranged on the first grid plate 31 when the new fuel elements are long. The first grid plate 31 and the second grid plate 32 together enable the mounting and fixing of new fuel elements.

In other embodiments, the supporting column 33 may be fixed on the bottom plate 41 of the supporting portion 40, and a connecting plate may be disposed at the other end of the supporting column 33 away from the bottom plate 41, and the connecting plate may be supported by the supporting column 33. And the same slide rails are arranged on the bottom plate 41 on the lower surface of the connecting plate. The mounting unit 30 comprises a first grid plate 31 and a second grid plate 32, each of the first grid plate 31 and the second grid plate 32 being provided with a slide, the first grid plate 31 being movably attached to the support 40, while the second grid plate 32 is movably attached below the connection plate, and the new fuel elements 200 are attached between the first grid plate 31 and the second grid plate 32, so that the mounting unit 30 is moved between the connection plate and the support 40.

In the present embodiment, the critical experiment apparatus further includes a control rod and/or a safety rod (not shown) disposed in a space between the guide tube 20 and the mounting unit 30, so that the control rod and/or the safety rod can be disposed without affecting the arrangement of the spent fuel and the new fuel elements, so that the control rod and/or the safety rod does not occupy the space of the spent fuel or the new fuel elements.

Further, the control and/or safety rods are plate-shaped, thereby reducing a space width occupied by the control and/or safety rods, and making it easier to dispose the control and/or safety rods in the gap between the guide tube 20 and the mounting unit 30. In addition, the control rod and/or the safety rod in the embodiment are designed in a strip plate shape, so that the surface area of the absorber can be effectively increased under the condition of a certain volume, and the value of the control rod and/or the safety rod is increased.

In the present embodiment, the core vessel 10 may be a tank-shaped vessel, for example, a stainless steel tank-shaped vessel. Specifically, the upper portion of the core vessel is opened so that the support portion 40, the mounting unit 30 loaded with new fuel elements, and the like can be arranged therein to complete the construction of the experimental apparatus for the critical experiment.

By adopting the critical experiment device in the embodiment of the invention, the critical experiment can be carried out in a combined mode of taking the new fuel with low enrichment degree as the fuel main body and the spent fuel as the experiment sample. The spent fuel is temporarily stored through the special shielding pipeline of the guide pipe, so that radioactive pollution of the spent fuel is avoided, and the situation of the spent fuel in a water pool can be simulated. The device can be used for developing a spent fuel critical reference experiment and a spent fuel reactivity measurement experiment and providing data support for spent fuel storage.

When the critical test is performed using the critical test apparatus in the present embodiment, water needs to be injected into the core vessel 10 as a moderator. In controlling the reactivity, the reactivity may be controlled by adjusting the height of the water level, or may also be controlled using a control rod.

In designing the critical experimental setup of the described embodiment, the Monte Carlo procedure may be utilized to perform core physical design work. The number and arrangement of new fuel elements in each mounting unit, as well as the arrangement of multiple mounting units, may be determined by critical mass calculations. In addition, theoretical calculation software can be used for determining the optimal slowing grid distance of the new fuel elements in the new fuel assembly so as to save fuel consumption.

UO at low enrichment₂As an example of the new fuel element, it is determined by the critical mass calculation that the new fuel element is mounted to the mounting unit 30 every 9 × 9 pieces, thereby constituting a new fuel assembly. And determining new fuel assemblies by critical mass calculation, forming a square grid arrangement according to a 3 x 3 array, leaving a second row and a second column of new fuel assemblies in the integral grid plate, arranging a guide pipe 20 for temporarily storing a spent fuel sample in the guide pipe, and sealing the top end of the guide pipe 20 to isolate the water environment of the spent fuel and the new fuel.

In order to simulate the interval between different fuel assemblies when spent fuel is stored in the pool, in the critical experimental apparatus of this embodiment, the new fuel elements are divided into 8 new fuel assemblies as shown in fig. 2, and the new fuel assemblies can freely move to form different slowing intervals. 2 sets of safety rods and 2 sets of control rods are arranged in the space between the spent fuel guide tube at the central position and the surrounding new fuel assembly, wherein the control rods can be plate-shaped.

Finally, all the components are arranged in a stainless steel tank as a core vessel, thereby completing the arrangement of the core for critical experiments. The lower end opening of the guide pipe 20 is positioned at the lower portion of the reactor core vessel, and the operation of moving the spent fuel into and out of the reactor core vessel can be performed from below the reactor core vessel.

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.

Claims

1. A critical experimental device for spent fuel is characterized by comprising:

the reactor core comprises a reactor core container, wherein the bottom of the reactor core container is provided with a guide hole;

the guide pipe is fixed at the guide hole in the reactor core container, the guide pipe is used for placing the spent fuel, and the guide hole is used for providing a hole channel for the input and the output of the spent fuel;

a plurality of mounting units arranged in an array around the guide pipe in the core vessel, the mounting units being used for mounting new fuel elements;

wherein the top end of the guide tube is closed for isolating the aqueous environment of the new fuel element.

2. The critical experimental apparatus of claim 1, wherein each of said mounting units is selectively movable in position.

3. The critical experimental apparatus of claim 2, further comprising: a support part provided at the bottom of the core vessel and disposed around the guide pipe;

each of the mounting units is movably coupled to the support portion.

4. The critical experimental device according to claim 3, wherein at least one sliding portion is provided on the mounting unit;

the supporting part is provided with a plurality of mutually perpendicular slide rails, the sliding part is matched with the slide rails, and the mounting unit is connected to the supporting part in a sliding manner.

5. The critical experimental apparatus of claim 3 or 4, further comprising: and the fixing piece is arranged on the supporting part or the mounting unit and is used for fixing the mounting unit on the supporting part.

6. The critical experimental device according to any one of claims 2 to 5, wherein the mounting units are movable relative to the support portion to adjust a spacing between the mounting units.

7. The critical experimental device of claim 4, wherein the support portion comprises:

the sliding rail is arranged on the bottom plate;

a bottom plate support fixed to the bottom of the core vessel, the bottom plate being connected to the bottom plate support.

8. The critical experimental apparatus of claim 3, wherein the mounting unit comprises:

a first grid plate movably connected to a support;

a second grid plate, the new fuel elements being mounted between the first and second grid plates;

and the support column is connected between the first grid plate and the second grid plate and is used for supporting the second grid plate.

9. The critical experimental apparatus of claim 1, wherein a plurality of said new fuel elements are disposed on said mounting unit in an array.

10. The critical experimental apparatus of claim 1, further comprising:

a control rod and/or a safety rod disposed in a space between the guide tube and the mounting unit.

11. The critical experimental apparatus of claim 10, wherein the control rod and/or the safety rod is plate-shaped.