Pressurized water reactor core with 24-month first circulation adopting full-ceramic microcapsule packaging fuel assembly and loading method of pressurized water reactor core

Abstract

The invention discloses a first circulation 24-month pressurized water reactor core adopting full-ceramic microcapsule packaged fuel assemblies and a loading method thereof, the reactor core is composed of 177 groups of full-ceramic microcapsule packaged fuel assemblies, each assembly is loaded in three areas according to the enrichment degree, the enrichment degrees of the assemblies in the three areas are all controlled within the range of 8%-10%, and the full-ceramic microcapsule packaged fuel assemblies are loaded in the three areas. The assemblies with the highest enrichment degree are placed in the outer area of the reactor core, the number of the assemblies is 72, the number of the burnable poison rods in part of the assemblies is 8, and the number of the burnable poison rods in the other part of the assemblies is 12; 32 groups of assemblies with relatively low enrichment degree are arranged in the middle area of the reactor core, and 12 burnable poison rods are arranged in each assembly; the assemblies with the lowest enrichment degree are arranged in the inner area of the reactor core, the number of the assemblies is 73, and the number of the burnable poison rods in each assembly is 12. According to the invention, the reactor core power is improved by 15% compared with that when rod-shaped fuel is adopted and can reach 3500MW, the first cycle life length reaches 24 months, and the safety and the economical efficiency of the reactor core are obviously improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear engineering, and in particular relates to a pressurized water reactor core with a first cycle of 24 months and a loading method thereof, which adopts all-ceramic microcapsule encapsulated fuel components. Background Art

[0002] At present, the core of a pressurized water reactor consists of 177 fuel assemblies, and the fuel assemblies are distributed in a checkerboard pattern. The reactor thermal output power is usually 3050-3180MW. The life of the core in the first cycle does not exceed 16 months, and the life of subsequent cycles is about 18 months. The core refueling cycle is short and the economy is poor.

[0003] In addition, the fuel rods in the fuel assembly of the above-mentioned pressurized water reactor core are made of UO 2 Core block, cladding is Zr alloy cladding. 2 Although the core has a high melting point, its thermal conductivity is low in a high temperature and high radiation environment, which will lead to steeper temperature gradients and thermal stresses, aggravating the consequences of accidents under accident conditions. Although the Zr alloy cladding has a small thermal neutron capture cross section, under high temperature accident conditions, the cladding temperature may rise high enough to cause a violent zirconium-water reaction, thereby producing a large amount of hydrogen, and in severe cases, even a hydrogen explosion may occur, causing a large amount of radioactive material to leak out, and the core safety is low. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a pressurized water reactor core with a first cycle of 24 months and a loading method thereof using all-ceramic microcapsule encapsulated fuel assemblies, which can ensure that the core power of the pressurized water reactor core composed of 177 groups of fuel assemblies is increased by 15% to 3500MW compared with the use of rod-shaped fuel without changing the core size, and the first cycle life length reaches 24 months, and the safety and economy of the core are significantly improved.

[0005] The technical solution of the present invention to solve the above technical problems is:

[0006] According to one aspect of the present invention, a method for loading a core of a pressurized water reactor for a first cycle of 24 months using all-ceramic microcapsule encapsulated fuel assemblies is provided, wherein the core is composed of 177 groups of all-ceramic microcapsule encapsulated fuel assemblies, and each all-ceramic microcapsule encapsulated fuel assembly is loaded in three zones according to the degree of enrichment, and the enrichment of the all-ceramic microcapsule encapsulated fuel assemblies in the three zones is controlled within the range of 8% to 10%, wherein:

[0007] The fully ceramic microcapsule-encapsulated fuel assemblies with the highest enrichment degree are placed in the outer core area. There are 72 groups of fully ceramic microcapsule-encapsulated fuel assemblies in the outer core area, of which some assemblies have 8 burnable poison rods and others have 12 burnable poison rods.

[0008] The all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment are arranged in the middle area of ​​the core. There are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies in the middle area of ​​the core, and the number of burnable poison rods in each assembly is 12;

[0009] The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core. There are 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies in the inner area of ​​the core, and the number of burnable poison rods in each assembly is 12.

[0010] Optionally, the enrichment of the fully ceramic microencapsulated fuel assembly in the three zones is 8%, 9% and 10% respectively, wherein:

[0011] Place the fully ceramic microcapsulated fuel assembly with an enrichment level of 10% in the outer area of ​​the core;

[0012] The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment level of 9% is arranged in the middle area of ​​the core;

[0013] The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment degree of 8% is arranged in the inner area of ​​the core.

[0014] Optionally, the number of all-ceramic microcapsule-encapsulated fuel assemblies with an enrichment degree of 10% and containing 8 burnable poison rods is 20 groups; the number of all-ceramic microcapsule-encapsulated fuel assemblies with an enrichment degree of 10% and containing 12 burnable poison rods is 52 groups.

[0015] Optionally, the burnable poison stick is Er 2 O 3 As the burnable poison, fuel particles and the burnable poison are dispersed in a SiC matrix to form the burnable poison rod.

[0016] Optionally, Er in the burnable poison stick 2 O 3 The weight percentage is 12.0%.

[0017] Optionally, the 235U enrichment in the burnable poison rods is the same as that of the fuel pellets.

[0018] According to another aspect of the present invention, a pressurized water reactor core with a first cycle of 24 months is provided, which is equipped with a fully ceramic microcapsule encapsulated fuel assembly and is loaded by the method described above.

[0019] Beneficial effects:

[0020] Compared with the prior art, the present invention can ensure that the core power of a pressurized water reactor core composed of 177 fuel assemblies is increased by 15% to 3500MW without changing the core shape and size, compared with the use of rod-shaped fuel, and the first cycle life reaches 24 months, and the core safety and economy are significantly improved.

[0021] In addition, due to the design characteristics of the coating layer, the fully ceramic microcapsule encapsulated fuel has better fission product containment capabilities, and has the significant advantages of high temperature resistance, corrosion resistance, and no hydrogen production. It can greatly reduce the possibility of large-scale release in severe accidents and the need for off-site emergency response, which is conducive to the simplification of nuclear power plant equipment systems and plays a vital role in improving economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of a pressurized water reactor core with a first cycle of 24 months using a fully ceramic microcapsule encapsulated fuel assembly according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0024] In the description of the present invention, it should be noted that the term "upper" and the like to indicate orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0025] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In view of the fact that the output thermal power of a pressurized water reactor core composed of 177 groups of fuel assemblies in the prior art is only 3050-3180MW, the life span of the first cycle core does not exceed 16 months, and the subsequent cycle is about 18 months, there are problems such as low core safety and poor economy. The present invention discloses a method for loading a pressurized water reactor core with a first cycle of 24 months using a fully ceramic microcapsule-encapsulated fuel assembly. The core is composed of 177 groups of fully ceramic microcapsule-encapsulated fuel assemblies. Each fully ceramic microcapsule-encapsulated fuel assembly is divided into three zones for loading according to the enrichment degree. The enrichment degrees of the fully ceramic microcapsule-encapsulated fuel assemblies in the three zones and the enrichment degrees of the fully ceramic microcapsule-encapsulated fuel assemblies in the three zones are all controlled within the range of 8%-10%, wherein:

[0027] The fully ceramic microcapsule-encapsulated fuel assemblies with the highest enrichment degree are placed in the outer core area. There are 72 groups of fully ceramic microcapsule-encapsulated fuel assemblies in the outer core area, of which some assemblies have 8 burnable poison rods and others have 12 burnable poison rods.

[0028] The all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment are arranged in the middle area of ​​the core. There are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies in the middle area of ​​the core, and the number of burnable poison rods in each assembly is 12;

[0029] The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core. There are 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies in the inner area of ​​the core, and the number of burnable poison rods in each assembly is 12.

[0030] Correspondingly, the present invention also discloses a pressurized water reactor core with a first cycle of 24 months and a fully ceramic microcapsule-encapsulated fuel assembly, which is loaded by the method described above.

[0031] Compared with the prior art, the present invention can ensure that the core power of a pressurized water reactor core composed of 177 fuel assemblies is increased by 15% to 3500MW without changing the core size, compared with the use of rod-shaped fuel, and the first cycle life can reach 24 months, and the core safety and economy are significantly improved.

[0032] Example 1

[0033] This embodiment discloses a method for loading a pressurized water reactor core with a first cycle of 24 months using a fully ceramic microcapsule encapsulated fuel assembly, which can be used for a pressurized water reactor core with a reactor output thermal power of 3500MW. The core is composed of 177 groups of fully ceramic microcapsule encapsulated fuel assemblies. Under the core power of this embodiment, in order to make the first cycle core length reach 24 months, and to avoid excessive enrichment, resulting in excessive fuel assembly costs and reduced core economy, the enrichment of the core fuel assembly is controlled within the range of 8% to 10%. In order to control the core reactivity, some fuel assemblies are provided with a number of burnable poison rods. The burnable poison in the burnable poison rods can introduce sufficiently large negative reactivity, and at the same time can well match the reactivity of the burnup reduction, so as to achieve core reactivity control.

[0034] In this embodiment, each all-ceramic microcapsule encapsulated fuel assembly is loaded into three zones according to the enrichment degree, and the enrichment degree of the all-ceramic microcapsule encapsulated fuel assembly in the three zones is controlled within the range of 8% to 10%, wherein:

[0035] The fully ceramic microcapsule-encapsulated fuel assemblies with the highest enrichment degree are placed in the outer core area. There are 72 groups of fully ceramic microcapsule-encapsulated fuel assemblies in the outer core area, of which some assemblies have 8 burnable poison rods and others have 12 burnable poison rods.

[0036] The all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment are arranged in the middle area of ​​the core. There are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies in the middle area of ​​the core, and the number of burnable poison rods in each assembly is 12;

[0037] The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core. There are 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies in the inner area of ​​the core, and the number of burnable poison rods in each assembly is 12.

[0038] In some embodiments, the enrichment of the all-ceramic microencapsulated fuel assembly in the three zones is 8%, 9% and 10%, respectively, wherein:

[0039] The fully ceramic microcapsule encapsulated fuel assembly with the highest enrichment of 10% is placed in the outer area of ​​the core, and as shown in Table 1, there are 72 groups of fully ceramic microcapsule encapsulated fuel assemblies with an enrichment of 10%, of which the number of burnable poison rods in some assemblies is 8 and the number of burnable poison rods in other assemblies is 12;

[0040] The above arrangement and quantity of the all-ceramic microcapsule encapsulated fuel assembly with 10% enrichment and the arrangement and quantity of the combustible poison are only one of the schemes that meet the requirements. Of course, there are other schemes, which will not be described one by one here;

[0041] The all-ceramic microcapsule encapsulated fuel assemblies with a relatively low enrichment of 9% are arranged in the middle area of ​​the core. There are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies with an enrichment of 9%, and the number of burnable poison rods in each assembly is 12;

[0042] The above arrangement and quantity of all-ceramic microcapsule encapsulated fuel assemblies with 9% enrichment and the arrangement and quantity of combustible poisons are only one of the schemes that meet the requirements. Of course, there are other schemes, which will not be described one by one here;

[0043] The fully ceramic microcapsule encapsulated fuel assemblies with the lowest enrichment of 8% are arranged in the inner area of ​​the core. There are 73 groups of fully ceramic microcapsule encapsulated fuel assemblies with an enrichment of 8%, and the number of burnable poison rods in each assembly is 12.

[0044] The above arrangement and quantity of the all-ceramic microcapsule encapsulated fuel assembly with 8% enrichment and the arrangement and quantity of the combustible poison are only one of the schemes that meet the requirements. Of course, there are other schemes, which will not be described here one by one.

[0045] Table 1

[0046]

[0047] Specifically, the height of the core active section is 365.76 cm, and the size of the ceramic microcapsule encapsulated fuel assembly is 12 feet. The ceramic microcapsule encapsulated fuel assembly includes a number of fuel rods, guide tubes and instrument tubes. In this embodiment, the ceramic microcapsule encapsulated fuel assembly includes 160 fuel rods, 8 guide tubes and 1 instrument tube. The fuel rods in each fully ceramic microcapsulated fuel assembly are arranged in a 13×13 manner. The fuel rods include a number of fuel core blocks, which are formed by fuel particles dispersed in a SiC matrix, and the fuel particles are composed of a fuel core and a cladding layer.

[0048] In some embodiments, as shown in Table 1, the number of all-ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 10% and containing 8 burnable poison rods is 20 groups; the number of all-ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 10% and containing 12 burnable poison rods is 52 groups.

[0049] In some embodiments, the burnable poison rod is Er 2 O 3 As the burnable poison, fuel particles and the burnable poison are dispersed in a SiC matrix to form the burnable poison rod.

[0050] In some embodiments, Er in the burnable poison rod 2 O 3The weight percentage is 12.0%, which is beneficial to controlling the flattening of the core reactivity distribution and is beneficial to core safety. In addition, the 12% content of combustible poisons is just right for this core. It is not too much to cause poison penalty, nor is it insufficient to cause poor core power flattening effect and Fdh exceeding the limit.

[0051] In some embodiments, the 235U enrichment in the burnable poison rod is the same as that in the fuel pellets, which is beneficial to the formulation of the burnable poison.

[0052] This embodiment also discloses a pressurized water reactor core with a first cycle of 24 months, which is a pressurized water reactor all-ceramic microcapsule encapsulated fuel assembly obtained by the above method. Its specific structure is as described in the above method and will not be repeated here.

[0053] Compared with the prior art, the method for loading the core of a pressurized water reactor with all-ceramic microcapsule encapsulated fuel assemblies for the first cycle of 24 months can ensure that the core power of a pressurized water reactor core composed of 177 fuel assemblies is lower than that of a core using traditional rod-shaped fuel (i.e., UO 2 The core block is in the shape of a round rod with a cladding on the outside. The power is increased by 15% to 3500MW, and the first cycle life is 24 months. The safety and economy of the core are significantly improved.

[0054] In addition, due to the design characteristics of the coating layer, the fully ceramic microcapsule encapsulated fuel has better fission product containment capabilities, and has the significant advantages of high temperature resistance, corrosion resistance, and no hydrogen production. It can greatly reduce the possibility of large-scale release in severe accidents and the need for off-site emergency response, which is conducive to the simplification of nuclear power plant equipment systems and plays a vital role in improving economic efficiency.

[0055] Example 2

[0056] This embodiment discloses a method for loading a pressurized water reactor core with a first cycle of 24 months of all-ceramic microcapsule encapsulated fuel assemblies, which is used for a pressurized water reactor core with a reactor output thermal power of 3500MW. The method is basically the same as the method described in Example 1, except that:

[0057] like Figure 1 As shown, the horizontal axis is arranged from right to left in sequence from AR, and the vertical axis is arranged from top to bottom in sequence from 1 to 15. This method includes

[0058] In the core, H3, K4, J4, H4, G4, F4, L5, K5, J5, H5, G5, F5, E5, M6, L6, K6, J6, H6, G6, F6, E6, D6, M7, L7, K7, J7, H7, G7, F7, E7, D7, N8, M8, L8, K8, J8, H8, G8, F8, E8, D8, C8, M9, L9, K9, J 73 sets of fully ceramic microencapsulated fuel assemblies with an enrichment of 8% and 12 burnable poison rods are arranged at positions 9, H9, G9, F9, E9, D9, M10, L10, K10, J10, H10, G10, F10, E10, D10, L11, K11, J11, H11, G11, F11, E11, K12, J12, H12, G12, F12, and H13;

[0059] 32 sets of fully ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 9% and containing 12 burnable poison rods are arranged at positions H2, K3, J3, G3, F3, M4, L4, E4, D4, M5, D5, N6, C6, N7, C7, P8, B8, N9, C9, N10, C10, M11, D11, M12, L12, E12, D12, K13, J13, G13, F13 and H14 of the core.

[0060] Arrange 20 sets of all-ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 10% and 8 burnable poison rods at positions J1, H1, G1, L2, E2, P5, B5, R7, A7, R8, A8, R9, A9, P11, B11, L14, E14, J15, H15, and G15 of the core;

[0061] 52 sets of fully ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 10% and containing 12 burnable poison rods are arranged at the K1, F1, M2, K2, J2, G2, F2, D2, N3, M3, L3, E3, D3, C3, P4, N4, C4, B4, N5, C5, R6, P6, B6, A6, P7, B7, P9, B9, R10, P10, B10, A10, N11, C11, P12, N12, C12, B12, N13, M13, L13, E13, D13, C13, M14, K14, J14, G14, F14, D14, K15, and F15 positions of the core.

[0062] It should be noted that Figure 1 A combination of letters and numbers is used to indicate the position of the fuel assembly in the core. For example, H3 indicates that the position of the fuel assembly in the core is H3.

[0063] This embodiment also discloses a pressurized water reactor core with a first cycle of 24 months, which is a fully ceramic microcapsule encapsulated fuel assembly obtained by the above method. The specific structure of the core is as described in the above method and will not be repeated here.

[0064] After calculation, the main parameters of the first cycle of the pressurized water reactor core of this embodiment are as shown in Table 2.

[0065] Table 2

[0066] Parameter name First cycle Cycle length (MWd / tU) 33000 Cycle length (EFPD) 665 Maximum nuclear enthalpy rise factor 1.428 Maximum hot spot factor 1.952 Critical boron concentration (ppm) 1363 Moderator temperature coefficient (pcm / ℃) -0.200 Maximum fuel consumption of components (MWd / tU) 37946

[0067] According to the calculation results of the main core parameters in Table 2, it can be determined that the core parameters meet the design criteria requirements.

[0068] Furthermore, a method for loading the core of a pressurized water reactor with a first cycle of 24 months using all-ceramic microcapsule encapsulated fuel assemblies can be determined. Without changing the core's external size, the all-ceramic microcapsule encapsulated fuel can be applied to a pressurized water reactor core of 177 assemblies. The core power is increased by 15% compared to when rod-shaped fuel is used, and the first cycle life reaches 24 months.

[0069] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for loading the core of a pressurized water reactor for the first 24 months of the cycle using all-ceramic microcapsule encapsulated fuel assemblies, characterized in that: The core consists of 177 sets of all-ceramic microcapsule encapsulated fuel assemblies, which are loaded into three zones according to their enrichment. The enrichment of all-ceramic microcapsule encapsulated fuel assemblies in the three zones is controlled within the range of 8% to 10%, including: The fully ceramic microcapsule-encapsulated fuel assemblies with the highest enrichment are placed in the outer area of ​​the core. There are 72 groups of fully ceramic microcapsule-encapsulated fuel assemblies with the highest enrichment, of which some assemblies have 8 burnable poison rods and others have 12 burnable poison rods. The all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment are arranged in the middle area of ​​the core. There are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment, and the number of burnable poison rods in each assembly is 12; The all-ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core. There are a total of 73 groups of all-ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment, and the number of burnable poison rods in each assembly is 12.

2. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first cycle of 24 months according to claim 1, characterized in that: The enrichment of the fully ceramic microcapsulated fuel assemblies in the three zones is 8%, 9% and 10% respectively, of which: Place the fully ceramic microcapsulated fuel assembly with an enrichment level of 10% in the outer area of ​​the core; The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment level of 9% is arranged in the middle area of ​​the core; The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment degree of 8% is arranged in the inner area of ​​the core.

3. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first 24 months of the cycle according to claim 1 or 2, characterized in that: The number of all-ceramic microcapsule encapsulated fuel assemblies with an enrichment of 10% and containing 8 burnable poison rods is 20; The number of all-ceramic microcapsule encapsulated fuel assemblies with an enrichment of 10% and containing 12 burnable poison rods is 52 sets.

4. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first cycle of 24 months according to claim 3, characterized in that: The burnable poison rod uses Er2O3 as the burnable poison, and fuel particles and the burnable poison are dispersed in a SiC matrix to form the burnable poison rod.

5. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first 24 months of the cycle according to claim 3, characterized in that: The weight percentage of Er2O3 in the burnable poison rod is 12.0%.

6. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first cycle of 24 months according to claim 1 or 2, characterized in that: The 235U enrichment in the burnable poison rods is the same as that in the fuel pellets.

7. A pressurized water reactor core with a first cycle of 24 months using all-ceramic microcapsule encapsulated fuel assemblies, characterized in that: The method according to any one of claims 1 to 6 is used for loading.

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