阅读说明：本技术 一种混凝土仓筒式乏燃料贮存装置的通风及辐射防护结构 (Ventilation and radiation protection structure of concrete silo type spent fuel storage device ) 是由 王梦琪 丁谦学 梅其良 黎辉 翁晨阳 郑征 毛兰方 史涛 陈祖盼 周岩 夏春梅 于 2021-09-22 设计创作，主要内容包括：本发明属于核电技术领域,具体公开了一种混凝土仓筒式乏燃料贮存装置的通风及辐射防护结构,包括混凝土屏蔽体和通风系统,通风流道采用迷宫式设计,特别是内层通风道与外层通风道形成方位角迷宫；通风流道中安装屏蔽栅格。本发明通风流道迷宫式设计大大提升了辐射屏蔽效果,此外屏蔽栅格在保持通风性能的基础上,提升了放射性中子和光子的衰减功能,降低了经由通风流道泄漏至外环境的辐照水平,从而降低工作人员运维过程中接受的辐照剂量,具有屏蔽效果好、屏蔽材料成熟,价格经济,且通风流道结构简单、建造方便的特点。(The invention belongs to the technical field of nuclear power, and particularly discloses a ventilation and radiation protection structure of a concrete silo type spent fuel storage device, which comprises a concrete shielding body and a ventilation system, wherein a ventilation flow channel adopts a labyrinth design, and particularly an azimuth angle labyrinth is formed by an inner-layer ventilation channel and an outer-layer ventilation channel; a shielding grid is installed in the ventilation flow channel. The ventilation runner labyrinth design greatly improves the radiation shielding effect, and in addition, the shielding grid improves the attenuation function of radioactive neutrons and photons on the basis of keeping the ventilation performance, and reduces the irradiation level leaked to the external environment through the ventilation runner, thereby reducing the irradiation dose received by workers in the operation and maintenance process.)

1. The utility model provides a ventilation and radiation protection structure of concrete silo formula spent fuel storage device, includes concrete shield system, ventilation system, its characterized in that: the ventilation flow channel adopts a labyrinth design, the inner layer ventilation channel and the outer layer ventilation channel form an azimuth angle labyrinth, and a shielding grid is arranged in the ventilation flow channel.

2. The ventilation and radiation protection structure of a concrete silo-type spent fuel storage device as claimed in claim 1, wherein the concrete shielding system comprises a base, a side cylinder and a top cover, and the side cylinder is provided with a ventilation flow passage.

3. The ventilation and radiation protection structure of a concrete silo-type spent fuel storage device as claimed in claim 2, wherein a certain air gap is provided between the base and the side cylinder.

4. The ventilation and radiation protection structure of a concrete silo-type spent fuel storage device as claimed in claim 1, wherein the ventilation system comprises a plurality of bottom air inlet channels and top air outlet channels and is of a labyrinth structure; the axial height of an air inlet at the inner side of the bottom air inlet runner is not higher than the bottom surface of the sealed container of the spent fuel assembly; the axial height of an air outlet at the inner side of the top air outlet flow channel is not lower than the top surface of the spent fuel assembly sealed container; the bottom air inlet channel and the top air outlet channel are in one-to-one correspondence at the azimuth angle.

5. The ventilation and radiation protection structure of a concrete silo-type spent fuel storage device as claimed in claim 1, wherein the ventilation system is of a three-path labyrinth design, and the ventilation channel comprises an inner layer ventilation channel, a middle annular ventilation channel and an outer layer ventilation channel.

6. The ventilation and radiation protection structure for a concrete silo-type spent fuel storage device as claimed in claim 5, wherein the inner ventilation channel and the outer ventilation channel of the ventilation channel are at different axial heights.

7. The ventilation and radiation protection structure of a concrete silo-type spent fuel storage device as claimed in claim 5, wherein the inner ventilation channel and the outer ventilation channel are at different azimuth angles, and the inner and outer ventilation channels form an azimuth angle labyrinth.

8. The ventilation and radiation protection structure of the concrete silo-type spent fuel storage device according to claim 5, wherein the middle annular ventilation channel is a full-circumferential through ventilation channel and/or each ventilation flow channel is provided with the middle annular ventilation channel independently.

9. The ventilation and radiation protection structure of the concrete silo-type spent fuel storage device as claimed in claim 1, wherein the ventilation channel is of a two-labyrinth design and comprises an inner layer ventilation channel, a middle annular ventilation channel and an outer layer ventilation channel.

10. The ventilation and radiation protection structure for a concrete silo-type spent fuel storage device as claimed in claim 9, wherein the inner ventilation channel and the outer ventilation channel of the ventilation channel are at the same axial height.

11. The ventilation and radiation protection structure for a concrete silo-type spent fuel storage device as claimed in claim 9, wherein the inner ventilation channel and the outer ventilation channel of the ventilation channel are at different azimuth angles, and the inner and outer ventilation channels form an azimuth angle labyrinth.

12. The ventilation and radiation protection structure for a concrete silo-type spent fuel storage device according to claim 9, wherein the middle annular channel is a full circumferential through ventilation channel and/or each ventilation channel is provided with a middle annular ventilation channel separately.

13. The ventilation and radiation protection structure of the concrete silo-type spent fuel storage device as claimed in claim 1, wherein the shielding grids installed in the ventilation flow channel are grid-type or grid-plate-type structures, and the ventilation channel shielding grids are made of carbon steel material.

Technical Field

The invention relates to the technical field of nuclear power, in particular to the field of third-generation passive nuclear power, and particularly relates to a ventilation and radiation protection structure of a concrete barrel type spent fuel storage device.

Background

The fuel storage pool of the nuclear power plant is limited in capacity, and generally can only meet the storage requirement of discharging spent fuel within more than ten years, and the design life of the nuclear power plant is 40-60 years. At present, a plurality of nuclear power plants in China already face the problem of insufficient storage capacity of spent fuel pools in the plants, the generation amount of the spent fuel in China will still increase year by year in the future, dry storage of the spent fuel is another temporary storage mode before final disposal of the spent fuel, and a plurality of nuclear power plants in China develop dry storage measures of the spent fuel at present. The spent fuel dry storage is to transport a spent fuel assembly which is cooled in a spent fuel pool for a certain age into a spent fuel dry storage container through a transport container for long-term storage.

Spent fuel refers to irradiated nuclear fuel that is discharged from a reactor upon irradiation by a nuclear reactor and is not used further in the present reactor. The spent fuel contains a large amount of radioactive nuclides, including proliferative materials which are not irradiated completely, fissile nuclides and transuranic nuclides generated by irradiation, and has the characteristics of strong radioactivity, long service life of the radioactive nuclides, strong toxicity, large heat productivity and the like. Radiation safety and decay heat derivation safety are important matters for ensuring the safety of the spent fuel dry storage device. In order to ensure the radiation safety of workers, the environment and the public, the spent fuel dry storage device is required to be provided with enough shielding bodies. In addition, in order to ensure the safety of fuel, equipment and the like in the spent fuel storage process, decay heat needs to be timely led out, and a ventilation flow channel needs to be arranged on the spent fuel storage container, so that the decay heat of the spent fuel assembly is timely led out to the external environment. Due to the arrangement of the ventilation flow channel, radioactive particles released by the spent fuel penetrate through the sealed container and then leak to the external environment through the ventilation channel, so that the radioactivity level of the local area of the ventilation opening is obviously increased. Therefore, the ventilation duct of the spent fuel dry storage device weakens the radiation shielding of the spent fuel dry storage device to a certain extent.

At present, the spent fuel dry storage device has a plurality of modes, and currently, factory modular spent fuel dry storage devices are all established in China, such as vertical barrel type module storage represented by Qinshan three factories, horizontal type module storage represented by Tianwan VVER and the like.

The concrete silo type spent fuel dry storage device is one of the important model selection directions of the spent fuel dry storage device because of good economy and expansibility. At present, in the existing concrete silo type spent fuel dry-type storage device, a plurality of ventilation channels are generally axially arranged in the arrangement of a ventilation opening, a single ventilation channel adopts a coaxial design, and the central axes of the single ventilation channel are positioned at the same azimuth angle. The shielding effect is poor based on the coaxial air duct, so that radioactive particle leakage beams passing through the air duct have great influence on the external radiation safety of the storage device, and the dosage rate level at the air opening is several times or even more than one order of magnitude higher than that outside the main shielding body. Particularly, for a spent fuel assembly with high fuel intensity and radioactivity, if a concrete silo type spent fuel dry-type storage device still adopts the linear ventilation design in the prior art or only adopts a single short labyrinth design in the axial direction, the dosage rate level at the ventilation opening is difficult to meet the requirement. For example, for a third generation passive nuclear power plant AP1000 or CAP1400 high-burn spent fuel, due to the strong radioactivity of the high-burn spent fuel, the prior art air duct design will cause the dose level at the air vent to approach 10mSv/h, resulting in excessively high external ambient radiation levels. In the future, high-fuel-consumption and strong-radioactivity spent fuel in China will be more and more.

Therefore, for the highly radioactive spent fuel, it is necessary to provide a ventilation and radiation protection structure suitable for the concrete silo type spent fuel storage device, so as to ensure the ventilation function, improve the radiation shielding effect of the ventilation flow channel, effectively reduce the radioactivity leaked to the external environment by the ventilation flow channel, and ensure the radiation safety of workers, the external environment and the public.

Disclosure of Invention

The invention aims to provide a ventilation and radiation protection structure of a concrete silo type spent fuel storage device, which overcomes the defects of the prior art, improves the shielding effect of an air duct, and effectively reduces neutron and photon radiation leaked to the environment through the air duct.

The technical problem solved by the invention can be realized by adopting the following technical scheme:

the invention provides a ventilation and radiation protection structure of a concrete silo type spent fuel storage device, which comprises a concrete shielding system and a ventilation system, wherein the concrete shielding system comprises a concrete tank and a concrete storage tank; the concrete shielding system comprises a base, a side barrel and a top cover. Wherein, the outer surface of the concrete shield body can be coated by carbon steel or stainless steel, and can also be not coated. The side barrel is provided with a ventilation flow channel due to the requirement of leading out decay heat.

Preferably, an air gap is provided between the base and the side cylinder to direct a portion of the radioactive particles to leak into the air gap, thereby reducing the level of leakage to the outside environment via the ventilation flow path. The ventilation system comprises a plurality of bottom air inlet channels and top air outlet channels and is of a labyrinth structure. Preferably, four bottom air inlet channels and four top air outlet channels are provided. And the axial height of an air inlet at the inner side of the bottom air inlet channel is not higher than the bottom surface of the spent fuel assembly sealed container. And the axial height of an air outlet at the inner side of the top air outlet flow channel is not lower than the top surface of the spent fuel assembly sealing container. The bottom air inlet channel and the top air outlet channel are in one-to-one correspondence at the azimuth angle, namely, the axes of the ventilation channels of the bottom air inlet channel and the top air outlet channel at the same azimuth angle are parallel in the axial direction.

Preferably, the ventilation flow channel adopts a three-path labyrinth design, and comprises an inner layer ventilation channel, a middle annular ventilation channel and an outer layer ventilation channel. The inner layer ventilation channel and the outer layer ventilation channel are at different axial heights. The inner layer ventilation channel and the outer layer ventilation channel are positioned at different azimuth angles, and the inner layer ventilation channel and the outer layer ventilation channel form an azimuth angle labyrinth. Specifically, a certain included angle is formed between the axis of the inner-layer air duct and the axis of the outer-layer air duct in the azimuth direction. Preferably, the included angle between the axis of the inner-layer ventilation duct and the axis of the outer-layer ventilation duct at the azimuth angle is 30-60 degrees.

Preferably, for the design of three labyrinth ventilation channels, the middle annular ventilation channel is a full-circumferential through ventilation channel, that is, all bottom ventilation channels or top ventilation channels share the middle annular ventilation channel.

Preferably, aiming at the design of three labyrinth ventilation channels, each ventilation channel is independently provided with a middle annular ventilation channel, and adjacent ventilation channels are not communicated.

Preferably, the ventilation channel adopts a two-labyrinth design, and comprises an inner layer ventilation channel, a middle annular ventilation channel and an outer layer ventilation channel. The inner layer ventilation channel and the outer layer ventilation channel are at the same axial height. The inner layer ventilation channel and the outer layer ventilation channel are positioned at different azimuth angles, and the inner layer ventilation channel and the outer layer ventilation channel form an azimuth angle labyrinth. Specifically, a certain included angle is formed between the axis of the inner-layer air duct and the axis of the outer-layer air duct in the azimuth direction. Preferably, the included angle between the axis of the inner-layer ventilation duct and the axis of the outer-layer ventilation duct at the azimuth angle is 30-60 degrees.

Preferably, for the design of two labyrinth ventilation channels, the middle annular ventilation channel is a full-circumferential through ventilation channel, that is, all bottom ventilation channels or top ventilation channels share the middle annular ventilation channel.

Preferably, aiming at the design of two labyrinth ventilation channels, each ventilation channel is independently provided with a middle annular ventilation channel, and adjacent ventilation channels are not communicated.

In the embodiment of the invention, the inner layer ventilation channel, the middle annular ventilation channel and the outer layer ventilation channel of the ventilation flow channel can be provided with a ventilation hole shielding grid in the air flow channel. The ventilation duct shielding grid may be a grid or grid-like structure. The preferred vent shield grid material is carbon steel. The radioactive particles reduce the level of leakage to the external environment by colliding with the shielding grid.

The invention has the beneficial effects that:

1. the labyrinth ventilation flow channel is adopted, so that the level of radioactive particles leaking to the external environment through the ventilation flow channel can be effectively reduced; compared with the traditional linear ventilation flow channel arrangement, the radiation shielding effect is improved by more than 1-2 orders of magnitude; compared with the traditional design that only labyrinth ventilation flow channels are adopted in the axial direction, the radiation shielding effect is improved by 4-20 times.

2. The concrete type shielding module and the ventilation runner are mature in shielding material process, economical in price, simple in structure and convenient to construct.

3. The shielding grid device is arranged in the ventilation flow channel, so that the ventilation capacity of the ventilation flow channel can be ensured, meanwhile, the radiation level of the external environment can be reduced by effectively reducing the radioactive neutron and photon radiation scattered out through the ventilation flow channel.

Drawings

FIG. 1 is a schematic structural diagram of a concrete silo-type spent fuel dry storage device of the present invention;

FIG. 2 is a schematic cross-sectional view of a vent passage according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of another embodiment of a vent channel according to the present invention;

FIG. 4 is a schematic cross-sectional view of another embodiment of a ventilation duct of the present invention;

FIG. 5 is a schematic structural diagram of a concrete silo-type spent fuel dry storage device according to an embodiment of the invention;

FIG. 6 is a schematic cross-sectional view of a vent passage according to an embodiment of the present invention;

FIG. 7 is a schematic cross-sectional view of another embodiment of a vent channel according to the present invention;

fig. 8 is a schematic structural view of a shielding grid for radioactive particles of ventilation ducts in an embodiment of the present invention.

In the figure: 1. a base; 2. a concrete shielding cylinder; 3. a top cover; 4. a spent fuel assembly seal cartridge; 5. a bottom air inlet channel; 6. a top air outlet flow channel; 11. an inner airway axis; 12. an outer layer air duct axis; 21. an inner layer air duct; 22. a middle annular ventilation duct; 23. an outer layer air duct; 24. an air inlet at the outer side of the bottom; 25. an air inlet at the inner side of the bottom; 26. an air outlet at the outer side of the top; 27. an air outlet at the inner side of the top; 30. the ventilation duct shields the grid.

Detailed Description

The invention is further described below with reference to the figures and examples. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Examples

As shown in fig. 1 and 5, the ventilation and radiation protection structure of a concrete silo type spent fuel storage device of the present invention comprises a concrete shielding system and a ventilation system, wherein the concrete shielding system comprises a base 1, a side cylinder 2 and a top cover 3. The main structures of the base 1, the side barrel 2 and the top cover 3 are all made of concrete, and the outer surface of the concrete shielding body can be coated by carbon steel or stainless steel or not.

The side cylinder body 2 is provided with a ventilation flow passage due to the requirement of leading out decay heat.

In this embodiment, a certain air gap is provided between the base 1 and the side cylinder 2, and some of the radioactive particles are guided to leak to the air gap, thereby reducing the level of leakage to the outside environment via the ventilation flow path.

In this embodiment, the ventilation system includes four bottom air inlet channels 5 and four top air outlet channels 6, which form vertical spaces with the sealed container 4 of spent fuel assemblies and the side shield 2 of the storage device. Cold air flows in from the bottom air inlet channel 5 and is heated by the spent fuel storage container, the air density is reduced, the cold air rises along the vertical air gap space between the spent fuel assembly sealing container 4 and the storage device side shielding body 2, finally flows out from the top air outlet channel 6, and meanwhile, the heat is taken away.

In this embodiment, the bottom air inlet channel 5 is composed of a bottom outside air inlet 24, a bottom inside air inlet 25, an inner air duct 21, a middle annular air duct 22, and an outer air duct 23. The axial height of the bottom inner air inlet 25 is not higher than the bottom surface of the sealed container 4 of the spent fuel assembly, and is preferably lower than the bottom surface of the sealed container 4 of the spent fuel assembly in the height direction.

In this embodiment, the top air outlet channel 6 is composed of a top outside air outlet 26, a top inside air outlet 27, an inner air duct 21, a middle annular air duct 22, and an outer air duct 23. The top inner air outlet 26 has an axial height not lower than the top surface of the sealed container 4 of the spent fuel assembly, and preferably has a height higher than the top surface of the sealed container 4 of the spent fuel assembly.

In this embodiment, the bottom air inlet channel 5 and the top air outlet channel 6 are in one-to-one correspondence with each other in the azimuth, that is, the ventilation channel axes of the bottom air inlet channel 5 and the top air outlet channel 6 at the same azimuth are axially parallel.

Referring to fig. 1 to 7, in order to reduce the radiation leakage of the ventilation flow path and enhance the radiation shielding capability thereof, the ventilation flow path has a labyrinth structure.

Referring to fig. 1-4, a first embodiment of the ventilation channel (i.e. the ventilation channel adopts a three-labyrinth design) is shown, and the ventilation channel includes an inner layer ventilation channel 21, a middle annular ventilation channel 22, and an outer layer ventilation channel 23.

As shown in fig. 1, the inner layer air passage 21 and the outer layer air passage 23 are at different axial heights.

As shown in fig. 2, 3 and 4, the inner layer air duct 21 and the outer layer air duct 23 are at different azimuth angles, and the inner and outer layer air flow passages form an azimuth angle labyrinth. Specifically, a certain included angle is formed between the axis 11 of the inner-layer air duct and the axis 12 of the outer-layer air duct in the azimuth direction.

In the embodiment, the included angle between the axis 11 of the inner layer air duct and the axis 12 of the outer layer air duct is 30-60 degrees in azimuth.

As shown in fig. 2, the intermediate annular air duct 22 is a full-circumferential through air duct. All bottom or top plenums share the middle annular plenum 22.

As shown in fig. 3, in another structure form of the intermediate annular ventilation channel, each ventilation channel is separately provided with the intermediate annular ventilation channel 22, and adjacent ventilation channels are not communicated.

Referring to fig. 5, 6 and 7, a second embodiment of the ventilation channel (i.e. the ventilation channel adopts a two-labyrinth design) is shown, and the ventilation channel includes an inner layer ventilation channel 21, a middle annular ventilation channel 22 and an outer layer ventilation channel 23.

As shown in fig. 5, the inner layer air path 21 and the outer layer air path 23 are at the same axial height.

As shown in fig. 6 and 7, the inner layer air duct 21 and the outer layer air duct 23 are at different azimuth angles, and the inner and outer layer air flow passages form an azimuth angle labyrinth. Specifically, a certain included angle is formed between the axis 11 of the inner-layer air duct and the axis 12 of the outer-layer air duct in the azimuth direction.

In the embodiment, the included angle between the axis 11 of the inner layer air duct and the axis 12 of the outer layer air duct is 30-60 degrees in azimuth.

As shown in fig. 6, the intermediate annular air duct 22 is a full-circumferential through air duct. All bottom or top plenums share the middle annular plenum 22.

As shown in fig. 7, fig. 7 is another structure form of the middle annular ventilation duct, and each ventilation flow passage is separately provided with the middle annular ventilation duct 22, and adjacent ventilation flow passages are not communicated.

As shown in fig. 8, the inner air passage 21, the middle annular air passage 22, and the outer air passage 23 may be provided with a ventilation hole shielding grid 30. The ventilation duct shielding grid may be a grid or grid-like structure. The preferred vent shield grid material is carbon steel. With the ventilation flow path kept open, the radioactive particles, by colliding with the shielding grid 30, enhance the attenuation of the particles, thereby reducing the level of leakage to the outside environment.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the present invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined by the appended claims and their equivalents.