Integrated reactor pressure vessel and refueling method

Abstract

The invention provides an integrated reactor pressure vessel and a refueling method, the pressure vessel comprises a cylinder and a bottom seal head arranged at the bottom of the cylinder, and the bottom seal head and the cylinder are detachably connected through a flange; at least one supporting boss is arranged in the bottom sealing head, the supporting boss is used for supporting a reactor core supporting plate and a reactor core shroud mounted on the reactor core supporting plate, and the fuel assembly is arranged in the reactor core shroud; in the refueling and refueling period, the bottom sealing head, the reactor core supporting plate, the reactor core shroud and the fuel assembly are transferred to a refueling pool together for fuel disassembly operation by disassembling the bottom sealing head. According to the pressure vessel, the bottom sealing head is detachably arranged at the bottom of the barrel, refueling is carried out from the bottom of the barrel, and the bottom sealing head, the reactor core supporting plate and the fuel assembly are transferred to the refueling pool together for centralized refueling during refueling, so that the refueling period is shortened, and due to refueling at the bottom of the barrel, the refueling efficiency is improved. Therefore, the problems that a traditional reactor top penetrating piece is difficult and tedious to disassemble and assemble, and long-distance deep reactor core reloading is difficult are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of reactor refueling, and in particular to an integrated reactor pressure vessel and a refueling method. Background Art

[0002] A reactor pressure vessel is used to contain fuel assemblies during operation and serves as the pressure boundary for the primary coolant. When the fuel assemblies reach a certain burnup and become spent fuel, the reactor needs to be shut down, the cover opened, and refueling carried out.

[0003] For traditional pressurized water reactors, refueling requires a refueling machine with thick shielding, usually unloading single fuel elements one by one, and then loading single fuel elements after unloading. Reactor refueling is a highly radioactive operation, and the operation process involves the highest level of radioactive exposure and the most harmful gases for personnel. Therefore, an overly long reactor shutdown and refueling cycle will reduce the economy of the reactor, and a long refueling cycle will increase the radiation dose to personnel and reduce the safety of the reactor.

[0004] Compared with large pressurized water reactors such as advanced passive pressurized water reactors, integrated small reactors adopt a natural circulation and fully integrated design. The pressurizer, heat exchanger, etc. are all built into the reactor pressure vessel. The reactor components have a compact structure, a large height difference, and a dense number of penetrations passing through the reactor pressure vessel head and the top of the containment vessel. If the existing method of opening the upper cover for refueling in pressurized water reactors is adopted, difficulties and complexities in disassembling and assembling the penetrations at the reactor top, and refueling at a long distance deep into the reactor core will be faced.

[0005] Based on this, the inventors of the present application propose an integrated reactor pressure vessel and a refueling method in order to solve one or more of the above technical problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defect of difficult refueling in existing integrated small reactors, and provide an integrated reactor pressure vessel and a refueling method.

[0007] The present invention solves the above technical problems by the following technical solutions:

[0008] The present invention provides an integrated reactor pressure vessel, including: a cylindrical body and a bottom head provided at the bottom of the cylindrical body, and the bottom head and the cylindrical body are detachably connected by a flange;

[0009] At least one supporting boss is provided in the bottom head, and the supporting boss is used to support the core support plate and the core shroud installed on the core support plate, and the fuel assemblies are arranged in the core shroud; wherein,

[0010] During refueling, by disassembling the bottom head, the bottom head, the core support plate, the core shroud and the fuel assembly are transferred to the refueling pool together for fuel disassembly operation.

[0011] According to an embodiment of the present invention, a first connection flange is provided at the bottom end of the cylinder body, a second connection flange is provided at the top end of the bottom head, and the first connection flange and the second connection flange are connected by at least two connection bolts.

[0012] According to an embodiment of the present invention, at least two first connection holes are formed in the first connection flange, and at least two second connection holes are formed in the second connection flange;

[0013] The first connection flange and the second connection flange are connected by sequentially passing the connection bolts through the first connection holes and the second connection holes.

[0014] According to an embodiment of the present invention, a stainless steel surfacing layer is provided in the inner cavity and the outer peripheral wall of the bottom head, in the first connection holes and in the second connection holes.

[0015] According to an embodiment of the present invention, at least two guiding blocks are circumferentially arranged on the outer peripheral side of the first connection flange of the cylinder body, and guiding holes are formed in the guiding blocks;

[0016] The guiding blocks are used for guiding the assembly of the cylinder body and the bottom head; or, the guiding blocks are used for guiding the installation of an external automatic device.

[0017] According to an embodiment of the present invention, at least two of the guiding blocks are evenly distributed on the outer peripheral side circumference of the first connection flange.

[0018] According to an embodiment of the present invention, a first chamber is formed in the cylinder body, and a second chamber communicating with the first chamber is formed in the bottom head;

[0019] At least one of the supporting bosses is provided at the bottom of the second chamber.

[0020] According to an embodiment of the present invention, at least one guiding member is provided on the outer peripheral wall of the core shroud;

[0021] At least one guiding boss is further provided in the second chamber of the bottom head, and the guiding boss and the guiding member are in radial cooperation along the cylinder body.

[0022] According to an embodiment of the present invention, the number of both the supporting bosses and the guiding bosses is at least two;

[0023] At least two of the supporting bosses are evenly distributed on the bottom of the second chamber, and at least two of the guiding bosses are evenly distributed on the peripheral wall of the second chamber.

[0024] According to an embodiment of the present invention, a top head is further provided at the top of the cylinder body, and the top head and the cylinder body are connected by at least two mating bolts.

[0025] The present invention also provides a refueling method for an integrated reactor pressure vessel, which is realized by using the integrated reactor pressure vessel as described above. The refueling method includes:

[0026] Using a bolt tensioner to disassemble the connecting bolts between the cylinder body and the bottom head;

[0027] Transporting the disassembled bottom head, core support plate and fuel assembly to the refueling pool together for refueling.

[0028] The positive and progressive effects of the present invention are as follows:

[0029] For the integrated reactor pressure vessel of the present invention, a detachable bottom head is provided at the bottom of the cylinder body, and refueling is carried out from the bottom of the cylinder body. During refueling, the bottom head, core support plate and fuel assembly are transported to the refueling pool together for centralized refueling, which is beneficial to shortening the refueling cycle. Moreover, because refueling is carried out at the bottom of the cylinder body, the problems of difficult and cumbersome disassembly and assembly of traditional top penetrations and difficult refueling of deep core at a long distance are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other features, properties and advantages of the present invention will become more obvious through the following description with reference to the drawings and embodiments, wherein:

[0031] Figure 1 is a sectional view of an integrated reactor pressure vessel of the present invention from an angle;

[0032] Figure 2 is Figure 1 a partial structural schematic diagram of the lower part of the cylinder body in ;

[0033] Figure 3 is Figure 1 a structural schematic diagram of the bottom head in ;

[0034] Figure 4 is Figure 1 a structural schematic diagram of the top head in.

[0035] 1. Cylinder body; 11. First connection flange; 111. First connection hole; 12. Guide block; 121. Guide hole; 13. First chamber; 14. Top head; 141. Mating bolt;

[0036] 2. Bottom head; 21. Support boss; 22. Second connecting flange; 221. Second connecting hole; 23. Connecting bolt; 24. Second chamber; 25. Guide boss;

[0037] 3. Core support plate;

[0038] 4. Fuel assembly;

[0039] 5. Core shroud; 51. Guide member. Detailed implementation manner

[0040] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above accompanying drawings description are intended to cover non-exclusive inclusion.

[0042] Please refer to Figures 1 to 4 , the present invention provides an integrated reactor pressure vessel, which includes a cylindrical body 1 and a bottom head 2 provided at the bottom of the cylindrical body 1. The bottom head 2 and the cylindrical body 1 are detachably connected by a flange.

[0043] Compared with the traditional refueling method at the top of the pressure vessel, the bottom of the integrated reactor pressure vessel is in the pool. In this application, the refueling method at the bottom of the pressure vessel is adopted. Thus, the disassembly and assembly of the entire reactor and the fuel loading and unloading operations are all carried out underwater, effectively reducing the personnel irradiation dose.

[0044] Furthermore, at least one support boss 21 is provided inside the bottom head 2. The support boss 21 is used to support the core support plate 3 and the core shroud 5 installed on the core support plate 3, and the fuel assembly 4 is arranged in the core shroud 5.

[0045] Among them, because the support boss 2 is provided inside the bottom head 2, the core support plate 3 and the in-core shroud 5 are supported and limited in the bottom head 2. Thus, during refueling and refitting, by disassembling the bottom head 2, the bottom head 2, the core support plate 3, the core shroud 5 and the fuel assembly 4 included therein can be transported to the refueling pool together for fuel disassembly operations.

[0046] That is, when performing underwater head opening and refueling, without removing the CV, RPV, and reactor head penetrations, the present invention only removes the bottom head 2, core support plate 3, fuel assemblies 4, and core shroud 5, and transports them to the refueling pool for fuel handling operations. Compared with the traditional single-fuel-assembly handling at the reactor head, the present invention transports the fuel assemblies 4 to the refueling pool for refueling, which is beneficial to improving the efficiency of reactor refueling; moreover, the present invention realizes an underwater refueling method in a coolant-full coverage environment, greatly reducing the irradiation dose of the operators and improving the safety of the refueling process.

[0047] Please refer to Figure 2 and Figure 3 , a first connecting flange 11 is provided at the bottom end of the cylinder body 1, a second connecting flange 22 is provided at the top end of the bottom head 2, and the first connecting flange 11 and the second connecting flange 22 are connected by at least two connecting bolts 23.

[0048] That is, the present invention uses the connecting bolts 23 to connect the cylinder body 1 and the bottom head 2, thereby meeting the requirements of refueling at the bottom of the cylinder body 1. During actual refueling, the bottom head 2 is disassembled and assembled.

[0049] Furthermore, at least two first connecting holes 111 are formed on the first connecting flange 11, and at least two second connecting holes 221 are formed on the second connecting flange 22; the first connecting flange 11 and the second connecting flange 22 are connected by sequentially passing the connecting bolts 23 through the first connecting holes 111 and the second connecting holes 221.

[0050] It can be seen that the number of the first connecting holes 111, the second connecting holes 221, and the connecting bolts 23 is the same. Specifically, the number of the three can be set according to actual needs and is not limited here.

[0051] To ensure the overall sealing performance of the pressure vessel, a double-sealing ring is also used to seal between the cylinder body 1 and the bottom head 2, thereby preventing external media from flowing into the cylinder body 1 and the bottom head 2. For the double-sealing ring, it can be arranged around the bottom end of the cylinder body 1 or the top end of the bottom head 2, and the specific arrangement method is not limited.

[0052] It should be noted that a stainless steel surfacing layer is provided in the inner cavity, outer peripheral wall, the first connecting holes 111, and the second connecting holes 221 of the bottom head 2.

[0053] Since the core fuel has been in the bottom head 2 and needs to be immersed in the cooling water to prevent the core from being directly exposed to the air, when the bottom head 2 is disassembled by a bolt tensioner, the bottom end of the cylinder body 1 needs to be immersed in water, so surfacing is required on the surface of the bottom head 2 and the first connecting holes 111 and the second connecting holes 221 to improve the corrosion resistance of the bottom end of the cylinder body 1 and the bottom head 2.

[0054] Please continue to refer toFigure 2 and Figure 3 On the outer circumferential side of the outer periphery of the first connecting flange 11 of the cylinder body 1, at least two guiding blocks 12 are provided, and guiding holes 121 are formed in the guiding blocks 12; the guiding blocks 12 are used to guide the assembly of the cylinder body 1 and the bottom head 2; alternatively, the guiding blocks 12 are used to guide the installation of an external automatic device.

[0055] Optionally, the number of the guiding blocks 12 is four, and the four guiding blocks 12 are evenly distributed on the circumferential side of the first connecting flange 11. On the one hand, the guiding blocks 12 can be used to provide mechanical guiding and positioning for the centering of the cylinder body 1 and the bottom head 2; they can also be used to provide guiding installation for an external automatic device, such as an automatic bolt tensioner.

[0056] That is to say, the guiding blocks 12 provide positioning interfaces for the automatic bolt tensioner. These interfaces can effectively fix the automatic bolt tensioner and provide precise positioning, thereby facilitating the automatic disassembly and assembly of bolts.

[0057] To improve the use stability of the automatic bolt tensioner, at least two guiding blocks 12 are evenly distributed around the circumferential circle of the first connecting flange 11.

[0058] Taking the above four guiding blocks 12 as an example, the four guiding blocks 12 are evenly distributed on the circumferential circle of the first connecting flange 11.

[0059] Please continue to refer to Figure 1 and Figure 3 In the cylinder body 1, a first chamber 13 is formed, and in the bottom head 2, a second chamber 24 communicated with the first chamber 13 is formed; at least one supporting boss 21 is provided at the bottom of the second chamber 24.

[0060] The first chamber 13 and the second chamber 24 are smoothly and transitionally connected. The core support plate 3, the fuel assembly 4 and the core shroud 5 are placed in the second chamber 24. After the bottom head 2 is disassembled, the bottom head 2 can carry the core support plate 3 and the fuel assembly 4 together to be transferred to the refueling water pool, thereby improving the refueling efficiency and realizing the underwater refueling method under the full coverage environment of the coolant.

[0061] Specifically, at least one guiding boss 25 is further provided in the second chamber 24 of the bottom head 2, and the guiding boss 25 is matched with a guiding member 51 provided on the core shroud 5; the guiding boss 25 is provided on the peripheral wall of the second chamber 24.

[0062] For example, a mating groove is provided on one side of the guiding boss 25 facing the core support plate 3, and the guiding member 51 is axially adapted to be inserted into the mating groove along the cylinder body 1. Thus, the cooperation between the guiding boss 25 and the guiding member 51 can form a support and positioning for the core support plate 3 in the radial direction, thereby avoiding the vibration of the fuel assembly 4 caused by the flow-induced vibration load generated by the coolant flowing through or the load under abnormal working conditions.

[0063] Preferably, the number of the supporting bosses 21 and the guiding bosses 25 is at least two; at least two supporting bosses 21 are evenly distributed on the bottom of the second chamber 24, and at least two guiding bosses 25 are evenly distributed on the peripheral wall of the second chamber 24.

[0064] It can be known that the number of the supporting bosses 21 and the guiding bosses 25 can be two, four, six, etc., which is not limited herein.

[0065] Please refer to Figure 1 and Figure 4 A top head 14 is further provided at the top of the cylinder body 1, and the top head 14 and the cylinder body 1 are connected by at least two mating bolts 141.

[0066] It should be noted that the top head 14 and the cylinder body 1 are connected by at least two mating bolts 141, and the number of the mating bolts 141 can be determined according to actual requirements, which is not limited herein.

[0067] Optionally, the pressure vessel is welded by a plurality of cylindrical forgings along its axial direction, which can be respectively composed of a pressure stabilizing section cylinder body, an upper nozzle section cylinder body, a lower nozzle section cylinder body and a lower cylinder body.

[0068] Among them, the top head 14 and the pressure stabilizing section cylinder body are connected by mating bolts, and the lower cylinder body and the bottom head 2 are connected by a flange.

[0069] During charging, the automatic positioning device installs the specified bolt assembly into the first connection hole 111 and the second connection hole 221, and pre-tightens the bolt to the designed pre-tightening load or the corresponding tensile amount, and automatically tightens the nut.

[0070] During discharging, the automatic unloading device unloads the bolt pre-tightening load, loosens the nut, and automatically positions and unscrews the bolt into the bolt storage rack.

[0071] It should be noted that the top of the core shroud 5 of the present invention does not interfere with the in-core components such as the basket cylinder body, so the core shroud 5 can be lifted out together with the core support plate 3 and the bottom head 2.

[0072] The present invention also provides an integrated reactor pressure vessel refueling method, which is realized by using the above integrated reactor pressure vessel. The refueling method includes:

[0073] Using a bolt tensioning machine to disassemble the connection bolts between the cylinder body and the bottom head;

[0074] Transferring the disassembled bottom head, core support plate and fuel assembly to the refueling pool for refueling.

[0075] Using the refueling method of the present invention, refueling is carried out under the cylinder body, and the underwater refueling method in an environment with full coverage of the coolant is realized, greatly reducing the radiation dose received by the operator and improving the refueling economy and safety of the reactor.

[0076] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0077] The present application uses specific terms to describe the embodiments of the present application. Such as "one embodiment", "an embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "an embodiment" or "one embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification is not necessarily the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the present application can be combined appropriately.

[0078] Although the present invention is disclosed above in preferred embodiments, it is not used to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention all fall within the protection scope defined by the claims of the present invention.

Claims

1. An integrated reactor pressure vessel, characterized in that, Comprising: A cylinder body and a bottom head arranged at the bottom of the cylinder body, and the bottom head and the cylinder body are detachably connected by a flange; At least one support boss is arranged inside the bottom head, and the support boss is used for supporting a core support plate and a core shroud installed on the core support plate, and a fuel assembly is arranged in the core shroud; wherein, During refueling and reshuffling, by disassembling the bottom head, the bottom head, the core support plate, the core shroud and the fuel assembly are transferred to the refueling pool together for fuel disassembly operation.

2. The integrated reactor pressure vessel according to claim 1, wherein A first connection flange is arranged at the bottom end of the cylinder body, a second connection flange is arranged at the top end of the bottom head, and the first connection flange and the second connection flange are connected by at least two connection bolts.

3. The integrated reactor pressure vessel according to claim 2, characterized in that, At least two first connection holes are formed in the first connection flange, and at least two second connection holes are formed in the second connection flange; The first connection flange and the second connection flange are connected by sequentially passing the connection bolts through the first connection holes and the second connection holes.

4. The integrated reactor pressure vessel according to claim 3, characterized in that, Stainless steel surfacing layers are arranged on the inner cavity and the outer peripheral wall of the bottom head, inside the first connection holes and inside the second connection holes.

5. The integrated reactor pressure vessel according to claim 2, wherein, At least two guiding blocks are arranged on the circumference of the outer side of the first connection flange of the cylinder body, and guiding holes are formed in the guiding blocks; The guiding blocks are used for guiding the assembly of the cylinder body and the bottom head; alternatively, the guiding blocks are used for installing and guiding an external automatic device.

6. The integrated reactor pressure vessel according to claim 3, characterized in that At least two of the guiding blocks are evenly distributed on the circumference of the outer side of the first connection flange.

7. The integrated reactor pressure vessel according to claim 1, characterized in that, A first chamber is formed inside the cylinder body, and a second chamber communicated with the first chamber is formed inside the bottom head; At least one of the support bosses is arranged at the bottom of the second chamber.

8. The integrated reactor pressure vessel according to claim 7, characterized in that, At least one guiding member is arranged on the outer peripheral wall of the core shroud; At least one guiding boss is further arranged in the second chamber of the bottom head, and the guiding boss and the guiding member are matched with each other along the radial direction of the cylinder body.

9. The integrated reactor pressure vessel according to claim 8, characterized in that, The number of the support bosses and the guiding bosses is at least two; At least two of the support bosses are evenly distributed at the bottom of the second chamber, and at least two of the guiding bosses are evenly distributed on the peripheral wall of the second chamber.

10. The integrated reactor pressure vessel according to claim 1, characterized in that, A top head is further arranged at the top of the cylinder body, and the top head and the cylinder body are connected by at least two mating bolts.

11. A refueling method for an integrated reactor pressure vessel, characterized in that, Realized by using the integral reactor pressure vessel according to any one of claims 1-19, the refueling method comprising: Using a bolt tensioner to disassemble the connection bolts between the cylinder body and the bottom head; Transferring the disassembled bottom head, core support plate and fuel assembly to the refueling pool together for refueling.

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