CN108461167B

CN108461167B - Vertical silo for dry storage of spent fuel in nuclear power plant

Info

Publication number: CN108461167B
Application number: CN201810094255.7A
Authority: CN
Inventors: 程呈; 张学岭; 唐琼辉; 杨寿海
Original assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd
Current assignee: China General Nuclear Power Corp; China Nuclear Power Engineering Co Ltd
Priority date: 2018-01-31
Filing date: 2018-01-31
Publication date: 2021-08-24
Anticipated expiration: 2038-01-31
Also published as: CN108461167A

Abstract

The invention discloses a vertical silo for dry-type storage of spent fuel in a nuclear power plant, which comprises a silo, a top cover and a bottom plate, wherein the silo comprises an internal silo and an external silo, a first annular cavity is arranged between the internal silo and the external silo, when a spent fuel storage tank is stored in the silo, a second annular cavity is arranged between the internal silo and the spent fuel storage tank, and an air inlet air flow passage communicated with the first annular cavity and the second annular cavity is also arranged between the bottom of the internal silo and the bottom plate; the upper area of the silo is provided with an air inlet communicated with the first annular cavity, the air inlet is provided with an air inlet protective cover, the upper part of the top cover is provided with an air outlet, the air outlet is provided with an air outlet protective cover, the bottom of the silo is fixedly connected with the bottom plate, and the top cover is fixed on the upper part of the silo. Compared with the prior art, the vertical silo for the dry storage of the spent fuel in the nuclear power plant can prevent the vent from being blocked, has high natural ventilation flow, good radiation shielding effect and safe integral structure.

Description

Vertical silo for dry storage of spent fuel in nuclear power plant

Technical Field

The invention belongs to the field of dry storage of spent fuel discharged from a reactor core of a nuclear power plant, and particularly relates to a vertical silo for dry storage of spent fuel of a nuclear power plant.

Background

The vertical silo (hereinafter referred to as the vertical silo) for the dry storage of the spent fuel is mainly used for storing and protecting a fuel storage tank for hermetically loading spent fuel components, and is used as an important item of nuclear safety, and the main functions of the vertical silo in the long-term storage process comprise: 1) providing spent fuel storage tank structure protection and radiation shielding; 2) an air convection channel is provided, and the natural circulation of air is utilized to remove decay heat of the spent fuel assembly, so that the spent fuel storage tank is fully cooled.

At present, the international widely and mature vertical silo structure is an integrated vertical cylinder with a hollow interior, is used for storing a spent fuel storage tank and mainly comprises a top cover, a cylinder body and a base. The top cover is independent of the barrel and is fixedly connected with the barrel through bolts. The barrel is of a single-layer thick-wall concrete structure, and the base is connected with the barrel in a welding mode. The spent fuel storage tank is freely arranged on the base of the silo, no constraint is generated, and the silo is freely arranged on the ground. The ventilation mode is that an air inlet with a smaller area and an opening to the outside is arranged in a local area at the bottom of the concrete silo, an air outlet with a smaller area and an opening to the outside is arranged in a local area at the upper end of the concrete silo, cold air enters the air inlet from the horizontal direction of the bottom, then enters an annular cavity between the spent fuel storage tank and the silo to take away spent fuel assembly decay heat and become hot air, finally the hot air is discharged from an air outlet at the top to the periphery in the horizontal direction, and natural circulation of the air is realized through the heat pressure difference of the air inlet and the air outlet, and finally the spent fuel storage tank is continuously cooled.

However, this structure has some problems:

1) the air inlet is positioned at the bottom, so that the equipment thermal safety and the sealing safety of the spent fuel in the storage tank are affected easily due to the blockage, and the ventilation opening is easy to be attacked from the outside and has potential safety hazards;

2) the ventilation openings are open and not shielded with the outside, and are easily blocked by foreign matters, so that the ventilation performance is influenced;

3) the natural ventilation heat exchange quantity is insufficient, and the spent fuel loading performance of equipment is influenced;

4) the radioactive dose level of the air inlet area at the bottom of the silo is high, and the radiation shielding safety of personnel is influenced;

5) the storage tank is not restrained, and the silo is easy to tip over under the accident condition, so that the structural safety of the equipment is influenced.

In view of the above, it is necessary to provide a vertical silo for dry storage of spent nuclear fuel in a nuclear power plant, which can prevent blockage of a vent, has high natural ventilation flow, good radiation shielding effect and safe overall structure.

Disclosure of Invention

The invention aims to: the vertical silo for the dry storage of the spent fuel in the nuclear power plant can prevent the blockage of the ventilation opening, has high natural ventilation flow, good radiation shielding effect and safe integral structure.

In order to achieve the purpose, the invention provides a vertical silo for dry-type storage of spent fuel in a nuclear power plant, which comprises a silo, a top cover and a bottom plate, wherein the silo comprises an internal silo and an external silo, a first annular cavity is arranged between the internal silo and the external silo, a second annular cavity is arranged between the internal silo and a spent fuel storage tank when the spent fuel storage tank is stored in the silo, and an air inlet air flow channel communicated with the first annular cavity and the second annular cavity is also arranged between the bottom of the internal silo and the bottom plate; the upper portion region of silo is provided with the air intake with first ring chamber intercommunication, and air intake department is provided with the air intake safety cover, top cap upper portion is provided with the air outlet, and air outlet department is provided with the air outlet safety cover, silo bottom and bottom plate fixed connection, the top cap is fixed on the upper portion of silo.

The vertical silo for the dry storage of the spent fuel in the nuclear power plant is an improvement, the internal silo comprises a cylinder body fixed with a bottom plate, the bottom of the cylinder body is provided with a plurality of through holes, and after the cylinder body is fixed on the bottom plate, the plurality of through holes form an air inlet air flow channel between the bottom of the internal silo and the bottom plate.

The vertical silo for the dry storage of the spent fuel in the nuclear power plant is improved, the internal silo comprises a barrel body and a bottom ribbed plate, the bottom ribbed plate is fixed on a bottom plate, the barrel body is fixed on the bottom ribbed plate, and an air inlet air flow channel is formed between the bottom of the barrel body and the bottom plate.

As an improvement of the vertical silo for the dry storage of the spent fuel in the nuclear power plant, the inner wall of the barrel is provided with a steel lining, a vertical ribbed plate is fixed on the steel lining, the bottom of the vertical ribbed plate extends to the bottom plate, the top interface of the vertical ribbed plate is lower than that of the barrel, and when a top cover is used for sealing, the bottom of the top cover is nested in the barrel and is supported at the top of the vertical ribbed plate.

As an improvement of the vertical silo for the dry storage of the spent fuel in the nuclear power plant, the internal silo also comprises an annular bottom plate arranged between the barrel body and a bottom ribbed plate, the annular bottom plate is welded with the bottom ribbed plate, and the vertical ribbed plate is fixedly connected with the bottom ribbed plate.

The vertical silo for the dry storage of the spent fuel in the nuclear power plant comprises a shell and a skirt edge arranged at the bottom of the shell, wherein a first support rib plate is arranged inside the shell, the first support rib plate is positioned between the external silo and the internal silo and is tightly contacted with the outer wall of the internal silo, the upper end of the first support rib plate is flush with the shell, the lower end of the first support rib plate is flush with the bottom of a barrel body of the internal silo, a fixing hole is formed in the skirt edge, a fixing screw rod is arranged on a bottom plate, and the external silo is fixed by inserting the fixing screw rod in the bottom plate through the fixing hole in the skirt edge.

The vertical silo for the dry-type storage of the spent fuel of the nuclear power plant further comprises a shielding ring, wherein a fixing hole is formed in the shielding ring, the shielding ring is inserted into a fixing screw rod on a bottom plate through the fixing hole, then is located on the skirt edge of the external silo and is fixed through a matched nut, and therefore the shielding ring, the external silo and the internal silo form an integral structural unit.

As an improvement of the vertical silo for the dry storage of the spent fuel in the nuclear power plant, the top cover comprises an outer shell and an inner shielding block, the inner part of the outer shell is of a spherical crown structure with a cavity, the inner shielding block is of a spherical crown structure and is fixed in the spherical crown cavity in the outer shell through a rib plate to form a spherical ventilation flow channel with a circular arc-shaped section, the top of the outer shell is provided with an air outlet, and the air outlet at the top of the outer shell is communicated with the spherical ventilation flow channel.

As an improvement of the vertical silo for the dry storage of the spent fuel in the nuclear power plant, the top cover also comprises a top cover skirt edge, the top cover skirt edge is fixed on the edge of the shell, and when the top cover is used for sealing, the top cover skirt edge is positioned on the inner edge of the top of the internal silo and is fixedly connected with the internal silo.

As an improvement of the vertical silo for the dry storage of the spent fuel in the nuclear power plant, the top cover further comprises a top cover connecting ring fixed at the top of the shell, the air outlet protective cover comprises a base plate, an annular enclosing plate and a second supporting rib plate, the upper end of the second supporting rib plate is fixedly connected with the base plate, the lower end of the second supporting rib plate is fixedly connected with the top cover connecting ring, and the annular enclosing plate is positioned at the outer edge of the base plate; preferably, the air outlet protection cover further comprises an air guide block, the air guide block is of an 1/4 round structure, and the air guide block is fixedly connected with the base plate and the annular enclosing plate respectively; further preferably, the air outlet protection cover further comprises an air outlet filter screen, and the air outlet filter screen is arranged at the lower end of the annular enclosing plate.

The vertical silo for the dry storage of the spent fuel in the nuclear power plant is improved in that the air inlet protective cover is arranged along the circumferential direction of the silo and comprises a top lap joint ring plate, an air inlet channel outer ring plate and an air inlet channel inner ring plate, wherein the air inlet channel outer ring plate is fixed on the outermost side of the top lap joint ring plate, the air inlet channel inner ring plate is fixed on the inner side of the top lap joint ring plate, and the innermost side of the top lap joint ring plate is fixed on the outer edge of the top of the internal silo.

As an improvement of the vertical silo for dry storage of spent fuel in a nuclear power plant, the air inlet protective cover further comprises an air guide groove, two sides of the air guide groove are respectively and fixedly connected with the outer annular plate of the air inlet duct and the inner annular plate of the air inlet duct, and preferably, the air guide groove is of a cavity structure with a semicircular section; further preferably, the air inlet protection cover is further provided with an air inlet protection filter screen, and the air inlet protection filter screen is arranged at the lower end of the outer ring plate of the air inlet duct.

Compared with the prior art, the vertical silo for the dry storage of the spent fuel in the nuclear power plant has the following technical effects:

1) on the one hand, even flood and its associated matters (silt, broken stone, vegetation and the like) appear under the accident condition, the problem that the thermal safety of equipment is influenced by the blockage of the ventilation opening can be avoided because the air inlet is higher from the ground surface; on the other hand, the air inlet is protected by the air inlet protection cover, and the air outlet is protected and shielded by the air outlet protection cover, so that the air inlet and the air outlet can be prevented from being blocked by external foreign matters, and the influence of the backflow effect such as rainstorm, tornado and the like on the ventilation performance is effectively avoided;

2) in the aspect of nuclear security, as the air inlet and the air outlet are both positioned in the high-level area of the equipment, the damage caused by external attack can be avoided, and the potential safety hazard of physical security of high-radioactivity nuclear-like materials (spent fuel assemblies) is eliminated;

3) in the aspect of spent fuel loading performance, because the ventilation area covers the annular full-range space to the maximum extent in the air inlet and air outlet regions, the silo has high-flow ventilation and heat exchange characteristics, and meanwhile, the spent fuel storage tank has the equipment performance of loading spent fuel assemblies with high heat release rate, particularly spent fuel assemblies with short cooling time and high fuel consumption level discharged from the reactor core after the final retirement of the nuclear power plant;

4) in the aspect of radiation shielding, because the integral thick-wall concrete shielding ring is additionally arranged outside the external silo, the dose of neutrons and gamma rays transmitted from the air flow channel of the air inlet in the full range of the bottom of the internal silo in the bottom of the silo in the 360-degree direction is effectively shielded, and the problem that the irradiation dose of operators is high in the open air inlet of the bottom area of the existing silo is solved;

5) in the aspect of structural safety, because the supporting rib plates with uniformly distributed axes are welded on the steel lining of the internal silo, the displacement constraint of the spent fuel storage tank is realized, the damage caused by the collision of the conventional spent fuel storage tank and the silo under the unrestrained mode of earthquake accident working conditions can be prevented, and meanwhile, the storage tank can be effectively prevented from sliding to a low position along the bottom plate in the tipping process of the silo, so that the gravity center of the whole silo is changed, and the accident risk of tipping the silo is reduced; in addition, as the shielding ring is additionally arranged on the periphery of the vertical silo, the coverage area of a bottom plate of the silo is increased, the length-diameter ratio is reduced, the gravity center is reduced, and the anti-overturning capability under the working conditions of earthquake and flood can be effectively improved.

Drawings

The vertical silo for dry storage of spent fuel in nuclear power plant and the beneficial technical effects thereof of the invention are explained in detail with reference to the accompanying drawings and the specific implementation mode, wherein:

fig. 1 is a schematic structural diagram of a vertical silo for dry storage of spent fuel in a nuclear power plant.

Fig. 2 is a top view of the vertical silo for dry storage of spent fuel in a nuclear power plant.

Fig. 3 is a side view of the vertical silo for dry storage of spent nuclear power plant fuel according to the present invention.

Fig. 4 is a partial sectional view of the vertical silo for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 5 is a top view of the vertical silo for dry storage of spent nuclear fuel in a nuclear power plant with the top cover removed.

Fig. 6 is a partial sectional view of an internal silo of the vertical silo for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 7 is a schematic view of the vertical silo fixing mode and ventilation for the dry storage of the spent fuel in the nuclear power plant.

Fig. 8 is a partial sectional view of an external silo of a vertical silo for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 9 is a top view of an external vertical silo for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 10 is a partial sectional view of an assembly structure of an external silo and an internal silo for the dry storage of spent fuel in a nuclear power plant.

Fig. 11 is a sectional elevation view of an external silo of the vertical silo for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 12 is a sectional elevation view of a vertical silo roof for dry storage of spent nuclear fuel from a nuclear power plant in accordance with the present invention.

Fig. 13 is a partial cross-sectional view of a vertical silo roof for dry storage of spent nuclear fuel from a nuclear power plant in accordance with the present invention.

Figure 14 is a partial cross-sectional view of the vertical silo roof shell for dry storage of spent nuclear power plant fuel in accordance with the present invention.

Fig. 15 is a schematic structural diagram of the vertical silo internal shielding device for the dry storage of the spent fuel in the nuclear power plant.

Fig. 16 is a sectional elevation view of the vertical silo air inlet protective cover for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 17 is a partial cross-sectional view of the vertical silo air inlet protective cover for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 18 is a sectional view of the vertical silo air outlet protective cover for the dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 19 is a bottom view of the vertical silo air outlet protective cover for dry storage of spent nuclear fuel in a nuclear power plant.

Fig. 20 is a schematic structural diagram of the vertical silo shielding ring for dry storage of spent fuel in nuclear power plants.

Fig. 21 is a schematic diagram of the vertical silo for dry storage of spent fuel in a nuclear power plant and the vertical silo in the prior art tilting under accident conditions.

Fig. 22 is an assembly structure diagram of the vertical silo for dry storage of spent fuel in nuclear power plant.

Fig. 23 is a schematic view of the vertical silo ventilation structure for the dry storage of spent fuel in a nuclear power plant.

Fig. 24 is a partial sectional view of an internal silo of a second embodiment of the vertical silo for dry storage of spent nuclear power plant fuel in accordance with the present invention.

Reference numerals:

10-a silo; 100-an internal silo; 1000-cylinder; 1000 a-pore channel; 1001-bottom rib; 1002-a vertical rib plate; 1003-annular baseplate; 1004-steel lining; 1005-outer side fixing screw rod; 1006-an inner fixing screw; 102-an external silo; 1020-a housing; 1024-skirt edge; 1025-fixing holes; 1026 — a first support rib; 104-a first ring cavity; 106-a second ring cavity; 108-air inlet air flow path; 110-an air inlet; 20-a top cover; 200-air outlet; 201-a housing; 202-inner shielding block; 203-ribbed plate; 204-a head connection ring; 205-skirt; 30-a bottom plate; 300-fixing the screw rod; 40-spent fuel storage tank; 50-air inlet protective cover; 500-top lap ring plate; 501-outer ring plate of air inlet duct; 502-air inlet duct inner ring plate; 503-air guiding groove; 504-air inlet protection filter screen; 60-air outlet protective cover; 600-a substrate; 601-annular coaming; 602-second support rib 602; 603-a wind guiding block; 604-air outlet filter screen; 70-a shield ring; 700-fixing holes.

Detailed Description

In order to make the objects, technical solutions and technical effects of the present invention more clear, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. 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.

Example 1

Referring to fig. 1 to 23, the vertical silo for dry storage of spent fuel in nuclear power plant of the present invention includes a silo 10, a top cover 20 and a bottom plate 30, wherein the silo 10 includes an internal silo 100 and an external silo 102, a first annular cavity 104 is provided between the internal silo 100 and the external silo 102, when the spent fuel storage tank 40 is stored in the silo 10, a second annular cavity 106 is provided between the internal silo 100 and the spent fuel storage tank 40, and an air inlet air channel 108 communicated with the first annular cavity 104 and the second annular cavity 106 is further provided between the bottom of the internal silo 100 and the bottom plate 30; an air inlet 110 communicated with the first annular cavity 104 is arranged in the upper region of the silo 10, an air inlet protective cover 50 is arranged at the air inlet 110, an air outlet 200 is arranged at the upper part of the top cover 20, an air outlet protective cover 60 is arranged at the air outlet 200, the bottom of the silo 10 is fixedly connected with the bottom plate 30, and the top cover 20 is fixed at the upper part of the silo 10.

Referring to fig. 4, 6 and 7, the internal silo 10 includes a cylinder 1000 and a bottom rib 1001, the cylinder 1000 is seated on the bottom rib 1001, and performs the functions of protecting the spent fuel storage tank 40 from the structure and shielding radiation, and is connected to the bottom rib 1001 by welding. In the illustrated embodiment, 8 bottom ribs 1001 are provided, the axial center ring is uniformly distributed at the bottom of the cylinder 1000, and the bottom is connected to the bottom plate 30 by welding. Through the supporting function of the bottom rib plate 1001, the cylinder body 1000 and the bottom plate 30 are separated from each other, and the space between the cylinder body 1000 and the bottom plate 30 forms the bottom annular air inlet air flow passage 108 of the internal silo 100, and because the annular air inlet air flow passage 108 has the unshielded full-range ventilation characteristic, the ventilation flow rate can be obviously improved.

The cylinder 1000 is of a hollow thick-wall concrete structure, a vertical ribbed plate 1002 fixedly connected with the bottom plate 30 is arranged on the inner wall of the cylinder, the vertical ribbed plate 1002 is connected with a bottom ribbed plate 1001 in a welding mode, the top interface of the vertical ribbed plate 1002 is lower than that of the cylinder 1000, and when the top cover 20 is used for sealing, the bottom of the top cover 20 is nested inside the cylinder 1000 and supported at the top of the vertical ribbed plate 1002. The outer diameter of the bottom of the top cover 20 is substantially equivalent to the inner diameter of the can 1000.

Further, as a preferred embodiment of the present invention, an annular bottom plate 1003 is further disposed at the bottom of the cylinder 1000, a steel lining 1004 is disposed on the inner wall of the cylinder 1000, the vertical rib 1002 is welded to the steel lining 1004, and the bottom rib 1001 is welded to the annular bottom plate 1003. The top of the cylinder 1000 is also provided with an outer fixing screw 1005 and an inner fixing screw 1006. In the illustrated embodiment, 8 outer fastening screws 1005 are provided, and are fixedly connected to the top lap ring plate 500 of the air inlet protection cover 50 by means of nuts, so as to finally fix the air inlet protection cover 50 to the periphery of the top of the internal silo 100. The inner fixing screws 1006 are designed with 8 screws, and are fixedly connected with the top cover skirt 205 on the top cover 20 by using matched nuts, so as to finally fix the top cover 20 on the inner upper part of the inner silo 100. In the illustrated embodiment, 8 vertical ribs 1002 are uniformly distributed and welded to the steel lining 1004 on the inner wall of the cylinder 1000, the height of the top of the vertical rib 1002 is lower than that of the cylinder 1000, and the height difference between the top of the vertical rib 1002 and the top of the cylinder 1000 can just accommodate the top cover 20, so that the lower part of the top cover 20 is nested in the inner silo 100. The height of the vertical rib 1002 is higher than that of the spent fuel storage tank 40, and after the spent fuel storage tank 40 is placed in the internal silo 100, an air flow passage communicated with the second annular cavity 106 is formed between the top of the spent fuel storage tank 40 and the top cover 20.

By adopting the structural design of the vertical rib plate 1002, on one hand, the displacement of the spent fuel storage tank 40 can be restrained, and the spent fuel storage tank can be prevented from colliding with the silo 10; on the other hand, the air flow channel of the second annular cavity 106 between the spent fuel storage tank 40 and the internal silo 100 can be isolated into 8 mutually independent and non-interfering vertical sub-channels, so that the stability of the whole ventilation and heat exchange is enhanced. Furthermore, by welding the vertical ribs 1002 to the floor 30, the overall structural strength of the internal silo 100 may be significantly enhanced.

Referring to fig. 8 to 11, an external silo 102 is fixed to the outside of an internal silo 100, a first annular cavity 104 for ventilation is formed between the external silo 102 and the internal silo 100, the height of the external silo 102 is lower than that of the internal silo 100, the top of the first annular cavity 104 between the external silo 102 and the internal silo 100 is used as an air inlet 110 of the silo 10, an air inlet protection cover 50 is fixed to the top of the internal silo 100, the air inlet protection cover 50 is located at the upper part of the external silo 102 in a spatial position, and the air inlet protection cover 50 protects the air inlet 110. The external silo 102 is primarily used to undertake vertical ventilation of the air intake and to protect the structure of the internal silo 100.

The external silo 102 includes a housing 1020 and a skirt 1024 secured to the outside of the bottom of the housing 1020. The shell 1020 is a thin-wall metal cylinder, the skirt 1024 is an annular steel plate, and the shell 1020 and the skirt 1024 are connected through welding. Further, the external silo 102 further includes a first supporting rib 1026 disposed on the inner wall of the housing 1020, and preferably, the first supporting rib 1026 is a T-shaped supporting rib, in the illustrated embodiment, a total of 8T-shaped supporting ribs are disposed and uniformly distributed on the inner wall of the housing 1020 by welding, the first supporting rib 1026 is located between the external silo 102 and the internal silo 100, and there is no fixed connection between the T-shaped supporting rib and the cylindrical body 1000 of the internal silo 100. In height, the upper end of the T-shaped support plate is flush with the housing 1020 and the lower end is flush with the bottom of the barrel 1000 of the internal silo 100. 8-12 fixing holes 1025 are formed in the cylinder body skirt edge 1024, and in the assembling process of the internal silo 100 and the external silo 102, the external silo 102 is inserted into the fixing screw 300 on the bottom plate 30 through the fixing holes 1025, so that a double-cylinder structure unit is formed.

When the external silo 102 is nested outside the internal silo 100, in terms of the ventilation structure design, a vertical first annular cavity 104 ventilation flow channel is formed between the inner wall of the external silo 102 and the outer wall of the internal silo 100, the first annular cavity 104 is divided into 8 mutually independent and non-interfering ventilation subareas by 8T-shaped support rib plates, and the stability of vertical ventilation at the air inlet side is enhanced. In the ventilation direction, the external natural air firstly rises to enter the annular closed air inlet protection screen 504 at the upper end of the silo 10, then enters the first annular cavity 104 to be adjusted by 180 degrees in the rear direction and ventilates towards the vertical downward direction under the shielding and flow guiding effects of the air inlet protection cover 50 at the upper end of the silo 10, and then enters the air inlet air flow passage 108 between the bottom of the internal silo 100 and the base 30. In terms of structural safety design, the 8T-shaped support rib plates are in close contact with the outer wall of the internal silo 100, and the structural support effect between the 8T-shaped support rib plates and the outer wall of the internal silo 100 improves the overall structural strength of the external silo 102 and simultaneously plays an auxiliary structural protection function for the internal silo 100.

Referring to fig. 12 to 15, the roof panel 20 includes an outer shell 201, an inner shielding block 202, a rib plate 203, a roof panel connecting ring 204, and a roof panel skirt 205, the outer shell 201 and the inner shielding block 202 are of an integrally molded and poured reinforced concrete structure, and the roof panel connecting ring 204, the rib plate 203, and the roof panel skirt 205 are steel plates. During long-term storage of spent fuel, the bottom of the top cover 20 nests inside the internal silo 100 and the top cover skirt 205 sits directly on the inner edge of the internal silo 100. The inside spherical crown cavity structure that is of shell 201, the outside leans out the structure for the conical surface, can prevent effectively that outside foreign matter from being detained and blockking up air outlet filter screen 604 in top cap 20 region, interior shielding piece 202 is the spherical crown structure, and fix in the inside spherical crown cavity of shell 201 through floor 203, it is convex sphere ventilation runner to form the section, can show to reduce the flow resistance of airing exhaust, the middle part of shell 201 is provided with the cylindrical air outlet 200 that link up, air outlet 200 link up with convex sphere ventilation runner. The top cover skirt 205 is a metal ring plate, is fixed on the edge of the outer shell 201, and is uniformly provided with 8 fixing holes along the circumference, and is used for embedding the inner fixing screw 1006 at the top of the internal silo 100, and fixing the top cover 20 at the top of the internal silo 100 through a matched nut, and simultaneously enabling the bottom of the top cover 20 to be located on the vertical rib plate 1002 of the internal silo 100. The top cover connection ring 204 is used for being connected with the lower end of the second support rib 602 in the air outlet protection cover 60 by welding.

In the illustrated embodiment, the housing 201 and the inner shielding block 202 are fixedly connected by 4 ribs 203. The main functions of the inner shielding block 202 are: 1) a streamline spherical ventilation flow channel is constructed, and the exhaust flow resistance inside the silo 10 is reduced; 2) as a radiation protection shield, after the top cover 20 is installed and fixed on the internal silo 100, the internal shielding block 202 is positioned right above the spent fuel storage tank, so that neutrons and gamma rays generated in the area right above the top cover of the spent fuel storage tank can be directly shielded, and the radiation dose of an air outlet area to operators and the public is reduced. Meanwhile, the cross section formed by the shell 201 and the inner shielding block 202 is an arc-shaped air flow channel, so that the shielding effect on neutrons and gamma rays generated by the spent fuel assembly is achieved, and the radiation dose of an air outlet area to operators and surrounding public is further reduced.

Referring to fig. 17, the air inlet protection cover 50 is a buckle-cap type structure, and includes a metal top lap ring plate 500, a metal air inlet duct outer ring plate 501 and a metal air inlet duct inner ring plate 502, the air inlet duct outer ring plate 501 is welded on the outermost side of the top lap ring plate 500, the air inlet duct inner ring plate 502 is welded on the inner side of the top lap ring plate 500, and keeps a proper distance from the innermost side of the top lap ring plate 500, the innermost side of the top lap ring plate 500 forms a skirt of the top lap ring plate 500, 8 fixing holes are formed in the skirt, the axial center of the fixing holes is uniformly distributed around the skirt, the air inlet protection cover 50 is nested in the peripheral area of the top of the internal silo 100 through the skirt, the air inlet protection cover 50 is inserted into the outer fixing screw 1005 of the top of the internal silo 100 through the fixing holes, and is fixed through the matching nuts, and fixed in the peripheral area of the top of the internal silo 100, and spatially position the air intake protection shroud 50 in an upper portion of the external silo 102. Meanwhile, the structural strength of the air inlet protection cover 50 is further enhanced by the annular fixed support after the air inlet duct inner ring plate 502 is nested with the inner silo 100 shell.

Further, the air inlet protection cover 50 is further provided with an air guide groove 503, the air guide groove 503 is of a concrete structure with a semicircular cavity cross section, the air guide groove 503 is formed by pouring concrete materials, two sides of the air guide groove are fixedly connected with the air inlet duct outer ring plate 501 and the air inlet duct inner ring plate 502 respectively, external natural air flow resistance is reduced through streamline structural design, structural safety function is born, and structural strength of the air inlet protection cover 50 is enhanced.

Furthermore, an air inlet protection screen 504 is disposed at the lower end of the outer annular plate 502 of the air inlet duct of the air inlet protection cover 50, so as to prevent the air inlet from being blocked by foreign matters.

In the air intake mode, the hidden vertical ventilation of the concrete silo is realized through the shielding and guiding effects of the air inlet duct outer ring plate 501, the air inlet duct inner ring plate 502 and the air guide groove 503, that is, under the shielding effect of the air inlet protection cover 50, external ambient air firstly enters the air inlet along the vertical upward direction, then changes the direction by 180 degrees along the circular arc-shaped air guide groove 503, and then enters the air inlet air flow channel 108 between the bottom of the internal silo 100 and the bottom plate 30 from the first ring cavity 104 along the vertical downward direction. Therefore, the hidden vertical ventilation design and the double protection of the annular closed air inlet protection filter screen 504 can fully prevent the air inlet from being blocked by external foreign matters.

Referring to fig. 18 and 19, the air outlet protection cover 60 is an integrated buckle cover structure, and includes a metal base plate 600, a metal annular enclosure 601 and a metal second support rib 602, the upper end of the second support rib 602 is connected to the base plate 600 by welding, the lower end of the second support rib 602 is connected to the top cover connection ring 204 by welding, and the annular enclosure 601 is located at the outer edge of the base plate 600. In the illustrated embodiment, there are 6 second support ribs 602 uniformly distributed around the center of the circle, thereby forming six independent full-range unshielded air outlets in the horizontal direction. Further, the air outlet protection cover 60 is also provided with an air guide block 603 of a concrete structure, the air guide block 603 is of an annular concrete structure with a section of 1/4 circles, the air guide block 603 is respectively welded with the substrate 600 and the annular enclosing plate 601, the edge angle air guide block 603 can obviously reduce air flow resistance of the air outlet at the top by adopting a streamline structure, and the air outlet is vertically and downwards discharged with hot air by shielding and guiding the air outlet through the annular enclosing plate 601 and the edge angle air guide block 603. Further, be provided with annular air outlet filter screen 604 at the lower extreme of annular bounding wall 601, air outlet filter screen 604 is the stainless steel filter screen, both ends respectively with annular bounding wall 601 and top cap 20 welded connection, through the vertical ventilation design of formula of hiding of full range and the annular filter screen duplicate protection that seals, can avoid outside foreign matter to block up the air outlet.

The bottom plate 30 is a circular steel plate, the bottom plate 30 is provided with fixing screws 300, in the illustrated embodiment, a total of 8 fixing screws are designed, and the axial center ring is uniformly distributed on the bottom plate 30 and is welded and fixed with the bottom plate 30.

Referring to fig. 20 to 22, as a preferred embodiment of the present invention, the vertical silo for storing spent nuclear fuel in a nuclear power plant further includes a shielding ring 70 disposed at an outer bottom region of the outer silo 102. The shield ring 70 is an integral concrete structure mounted at the outer bottom end of the housing 1020 of the outer silo 102. The shield ring 70 is provided with 12 through fixing holes 700, after the shield ring 70 is inserted into the fixing screw 300 on the bottom plate 30, the shield ring 70 is directly seated on the skirt 1024 of the outer silo 102, and then the shield ring 70, the outer silo 102 and the inner barrel silo 100 are fixedly connected by using a matching nut, so that the shield ring 70, the outer silo 102 and the inner barrel silo 100 are an integral structural unit.

Because the circumferential air inlet air flow channel 108 between the bottom of the internal silo 100 and the bottom plate 30 adopts an unshielded full-range ventilation design, for the bottom area, only the thin-wall shell 1020 of the external silo 102 is used as the only shielding layer of the air inlet air flow channel 108 area, in order to strengthen the radiation shielding effect of the bottom air inlet air flow channel 108 area, the integrated thick-wall concrete shielding ring 70 is additionally arranged outside the external silo 102, thereby realizing the radiation shielding of neutrons and gamma rays generated by a spent fuel storage tank, and effectively reducing the radiation dose of the whole silo bottom area while realizing the unshielded full-range ventilation of the air inlet air flow channel 108 of the internal silo 100. In addition, as the shielding ring 70 is additionally arranged on the periphery of the external silo 102, the coverage area of the bottom plate 30 is increased, the length-diameter ratio is reduced, the gravity center is lowered, and the anti-overturning capability under the working conditions of earthquake and flood can be effectively improved.

The operation process of the vertical silo for the dry storage of the spent fuel in the nuclear power plant comprises the following steps:

1) the integrated top cover (the air outlet protection cover 60 and the top cover 20) is moved away by a special crane, and an adapter is installed at the top of the vertical silo;

2) hoisting the matched transfer container loaded with the spent fuel storage tank to a top adapter of the vertical silo, and removing a cover plate of the transfer container by using an adapter supporting plate;

3) hoisting the spent fuel storage tank by using a crane and slowly lowering the spent fuel storage tank, and slowly hoisting the spent fuel storage tank from the inside of the transfer container to the inside of the cylinder body 1000 of the internal silo 100;

4) the adapter is removed and the integrated top cap (air outlet protection cap 60 and top cap 20) is hoisted to the top of the internal silo 100 using a special crane and secured using bolts.

Fig. 23 is a schematic view of the vertical silo ventilation structure for dry storage of spent fuel in nuclear power plant, the ventilation process mainly includes:

1) after the spent fuel storage tank 40 is placed in an annular cavity formed by the internal silo 100 and the base 30, natural air in the external environment firstly flows upwards from an air inlet protection filter screen 504 at the bottom of an air inlet protection cover 50 positioned at the upper end of the silo 10, and the air flow direction changes 180 degrees after passing through an annular concrete ventilation groove 503 with the section of 1/2 circular in the air inlet protection cover 50;

2) natural air flows vertically downward along a first annulus 104 formed by the inner silo 100 and the outer silo 102;

3) when the natural air reaches the bottom of the first annular cavity 104, the air flow direction is further turned by 90 degrees and enters a full-range unshielded air inlet air flow channel 108 formed by bottom rib plates 1001 between the internal silo 13 and the bottom plate 30;

4) the natural air enters a second annular cavity 106 formed by the spent fuel storage tank 40 and the internal silo 100, and after being heated by the spent fuel assembly, the decay heat of the spent fuel assembly is taken away and flows vertically upwards;

5) after reaching the top cover 20, the air enters a spherical low-resistance ventilation flow channel between the concrete shell 201 and the inner shielding block 202 and then passes through the vertical ventilation opening 200 in a centralized manner;

6) then the air enters the whole range of the non-shielding air outlet formed by the second supporting rib plates 602 of the air outlet protection cover 60 after being turned by 90 degrees, finally the air is vertically exhausted downwards after passing through a circular annular concrete air guide block 603 with the inner section of 1/2, and the air is exhausted from an air outlet filter screen 604 at the bottom of the air outlet protection cover 60;

7) under the influence of the hot pressure difference between the air inlet and the air outlet, hot air can flow upwards vertically in the direction of 180 degrees and is discharged to the surrounding atmosphere, so that decay passive natural ventilation circulation heat dissipation of the spent fuel assembly is realized.

Example 2

Fig. 24 is a schematic view of a vertical silo for dry storage of spent fuel in a nuclear power plant according to a second embodiment of the present invention, which is basically configured in the same manner as in example 1, except that: the internal silo 100 comprises a cylinder body 1000 fixed with the bottom plate 30, a plurality of through holes 1000a are uniformly arranged at intervals at the bottom of the cylinder body 1000, and the plurality of through holes 1000a form an air inlet air flow channel between the bottom of the internal silo 100 and the bottom plate 30.

The inner wall of barrel 1000 is provided with steel lining 1004, and the welding has vertical floor 1002 on steel lining 1004, and the bottom of vertical floor 1002 extends to bottom plate 30, and with bottom plate 30 welded fastening, the top interface of vertical floor 1002 is less than barrel 1000 top interface, and when carrying out the closing cap with the top cap (not shown), top floor nestification is inside barrel 1000, and supports the top at vertical floor 1002.

Other arrangements of the external silo, the air inlet protection cover, the air outlet protection cover, the shielding ring, etc. are the same as those of embodiment 1, and are not described herein again.

The present invention can be modified and adapted appropriately from the above-described embodiments, according to the principles described above. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A vertical silo for dry-type storage of spent fuel in a nuclear power plant comprises a silo, a top cover and a bottom plate, and is characterized in that the silo comprises an internal silo and an external silo, a first annular cavity is arranged between the internal silo and the external silo, when a spent fuel storage tank is stored in the silo, a second annular cavity is arranged between the internal silo and the spent fuel storage tank, and an air inlet air flow passage communicated with the first annular cavity and the second annular cavity is also arranged between the bottom of the internal silo and the bottom plate; an air inlet communicated with the first annular cavity is formed in the upper region of the silo, an air inlet protection cover is arranged at the air inlet, an air outlet is formed in the upper portion of the top cover, an air outlet protection cover is arranged at the air outlet, the bottom of the silo is fixedly connected with the bottom plate, and the top cover is fixed to the upper portion of the silo; the air inlet protection cover is arranged along the circumferential direction of the silo and comprises a top lap joint ring plate, an air inlet channel outer ring plate and an air inlet channel inner ring plate, the air inlet channel outer ring plate is fixed on the outermost side of the top lap joint ring plate, the air inlet channel inner ring plate is fixed on the inner side of the top lap joint ring plate, and the innermost side of the top lap joint ring plate is fixed on the outer edge of the top of the internal silo, so that the air inlet protection cover is positioned on the upper portion of the external silo, and a vertical air inlet is formed between the air inlet channel outer ring plate and the external silo; under the shielding effect of the air inlet protective cover, external environment air firstly enters the air inlet along the vertical upward direction and then enters the first annular cavity after changing the direction.

2. The vertical silo for the dry storage of the spent nuclear fuel in the nuclear power plant as claimed in claim 1, wherein the internal silo comprises a cylinder body fixed with a bottom plate, the bottom of the cylinder body is provided with a plurality of through holes, and after the cylinder body is fixed on the bottom plate, the plurality of through holes form an air inlet air flow channel between the bottom of the internal silo and the bottom plate.

3. The vertical silo for the dry storage of the spent nuclear fuel in the nuclear power plant as claimed in claim 1, wherein the internal silo comprises a cylinder body and a bottom rib plate, the bottom rib plate is fixed on the bottom plate, the cylinder body is fixed on the bottom rib plate, and an air inlet air flow passage is formed between the bottom of the cylinder body and the bottom plate.

4. The vertical silo for the dry storage of the spent nuclear fuel in the nuclear power plant as claimed in claim 3, wherein the inner wall of the barrel is provided with a steel lining, vertical ribs are fixed on the steel lining, the bottoms of the vertical ribs extend to the bottom plate, the top interfaces of the vertical ribs are lower than the top interfaces of the barrel, and when the top cover is used for sealing, the bottom of the top cover is nested inside the barrel and supported on the tops of the vertical ribs.

5. The vertical silo for the dry storage of the spent nuclear fuel in the nuclear power plant as claimed in claim 4, wherein the internal silo further comprises an annular bottom plate arranged between the barrel and the bottom rib plate, the annular bottom plate is welded with the bottom rib plate, and the vertical rib plate is fixedly connected with the bottom rib plate.

6. The vertical silo for the dry storage of the spent fuel in the nuclear power plant as claimed in any one of claims 2 to 5, wherein the external silo comprises a shell and a skirt edge arranged at the bottom of the shell, a first support rib plate is arranged inside the shell, the first support rib plate is positioned between the external silo and the internal silo and is in close contact with the outer wall of the internal silo, the upper end of the first support rib plate is flush with the shell, the lower end of the first support rib plate is flush with the bottom of the barrel body of the internal silo, a fixing hole is formed in the skirt edge, a fixing screw is arranged on the bottom plate, and the external silo is fixed by inserting the fixing hole in the skirt edge into the fixing screw on the bottom plate.

7. The vertical silo for the dry-type storage of the spent fuel in the nuclear power plant as claimed in claim 6, wherein the vertical silo for the dry-type storage of the spent fuel in the nuclear power plant further comprises a shielding ring, the shielding ring is provided with a fixing hole, the shielding ring is inserted into a fixing screw rod on the bottom plate through the fixing hole, then is seated on the skirt edge of the external silo, and is fixed through a matched nut, so that the shielding ring, the external silo and the internal silo form an integral structural unit.

8. The vertical silo for the dry storage of the spent nuclear fuel in the nuclear power plant as claimed in claim 1, wherein the top cover comprises an outer shell and an inner shielding block, the inside of the outer shell is of a spherical crown structure with a cavity, the inner shielding block is of a spherical crown structure and is fixed in the spherical crown cavity inside the outer shell through a rib plate to form a spherical ventilation channel with a circular arc-shaped section, the top of the outer shell is provided with an air outlet, and the air outlet at the top of the outer shell is communicated with the spherical ventilation channel.

9. The vertical silo for dry storage of spent nuclear fuel from a nuclear power plant as claimed in claim 8, wherein the top cover further comprises a top cover skirt secured to an edge of the outer shell, the top cover skirt seated on and fixedly attached to the top inner edge of the internal silo when the top cover is closed.

10. The vertical silo for the dry storage of spent nuclear fuel in a nuclear power plant as claimed in claim 9, wherein the top cover further comprises a top cover connecting ring fixed on the top of the housing, the air outlet protection cover comprises a base plate, an annular shroud and second support ribs, the upper ends of the second support ribs are fixedly connected with the base plate, the lower ends of the second support ribs are fixedly connected with the top cover connecting ring, and the annular shroud is located at the outer edge of the base plate, so that a vertical air outlet is formed between the annular shroud and the top cover connecting ring; under the shielding effect of the air outlet protective cover, hot air in the vertical silo is vertically discharged downwards from the air outlet.

11. The vertical silo for dry storage of spent nuclear fuel in nuclear power plant according to claim 10, wherein the air outlet protection cover further comprises an air guide block, the air guide block is 1/4 round structure, and the air guide block is fixedly connected with the base plate and the annular enclosing plate respectively.

12. The vertical silo for dry storage of spent nuclear fuel in nuclear power plant according to claim 10, wherein the air outlet protection cover further comprises an air outlet screen disposed at a lower end of the annular enclosure.

13. The vertical silo for the dry-type storage of the spent nuclear fuel in the nuclear power plant according to claim 1, wherein the air inlet protection cover further comprises an air guide groove, and two sides of the air guide groove are fixedly connected with the outer annular plate of the air inlet duct and the inner annular plate of the air inlet duct respectively.

14. The vertical silo for the dry-type storage of the spent nuclear fuel in the nuclear power plant according to claim 13, wherein the air guide groove has a cavity structure with a semicircular cross section.

15. The vertical silo for dry-type storage of spent nuclear fuel in nuclear power plant according to claim 13, wherein the air inlet protection cover is further provided with an air inlet protection screen, and the air inlet protection screen is arranged at the lower end of the outer ring plate of the air inlet duct.