Pressurized water reactor core with 18-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 18-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 degree of the assemblies in the three areas is controlled within the range of 8%-10%, and the full-ceramic microcapsule packaged fuel assemblies are loaded in the three areas. 12 burnable poison rods are arranged in each group of components, the components with the highest enrichment degree are arranged in the outer area of the reactor core, and 72 groups of components with the highest enrichment degree are arranged in total; the assemblies with relatively low enrichment degrees are arranged in the middle area of the reactor core, and the total number of the assemblies with relatively low enrichment degrees is 32; the assemblies with the lowest enrichment degree are arranged in the reactor core, and the total number of the assemblies with the lowest enrichment degree is 73. According to the invention, on the premise of not changing the appearance and size of the pressurized water reactor core consisting of 177 groups of fuel assemblies, the power of the reactor core is increased by 40% compared with that of the pressurized water reactor core consisting of rod-shaped fuel and can reach 4400MW, the first cycle life length reaches 18 months, and the nuclear fuel utilization rate and the economical efficiency are obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear engineering, and in particular relates to a pressurized water reactor core with a first cycle of 18 months using all-ceramic microcapsules to encapsulate fuel assemblies, and a loading method thereof. Background Art

[0002] At present, the core of a pressurized water reactor consists of 177 fuel assemblies, using 12-foot rod-shaped fuel assemblies. The reactor output thermal power is 3050-3180MW, the first cycle core life is only 12-16 months, the core refueling cycle is short, and the economy is poor. In addition, since the fuel assembly of the above-mentioned pressurized water reactor core adopts the design of "UO2 pellet-Zr alloy cladding", there is a risk of hydrogen explosion under accident conditions, which is not conducive to reactor safety. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a pressurized water reactor core with a first cycle of 18 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 40% to 4400MW compared with the use of rod-shaped fuel without changing the core size, and the first cycle life can reach 18 months, thereby significantly improving the safety and economy of the reactor.

[0004] The technical solution of the present invention to solve the above technical problems is:

[0005] According to one aspect of the present invention, a method for loading a core of a pressurized water reactor with a first cycle of 18 months using a fully ceramic microcapsule encapsulated fuel assembly is provided. The core is composed of 177 groups of fully ceramic microcapsule encapsulated fuel assemblies. The fully ceramic microcapsule encapsulated fuel assemblies are divided into three zones for loading according to their enrichment. The enrichment of the fully ceramic microcapsule encapsulated fuel assemblies in the three zones is controlled within the range of 8% to 10%, and each group of fully ceramic microcapsule encapsulated fuel assemblies is provided with 12 combustible poison rods, wherein:

[0006] Placing the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree in the outer area of ​​the core, and a total of 72 groups of the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree;

[0007] Arrange all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment in the middle area of ​​the core, and there are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment;

[0008] The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core, and there are 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment.

[0009] Optionally, the enrichment of the fully ceramic microencapsulated fuel assembly in the three zones is 8%, 9% and 10% respectively, wherein:

[0010] The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment level of 10% is placed outside the core.

[0011] The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment level of 9% is arranged in the middle area of ​​the core;

[0012] The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment degree of 8% is arranged in the inner area of ​​the core.

[0013] Optionally, the burnable poison rod uses Er2O3 as the burnable poison, and the fuel particles and the burnable poison are dispersed in the SiC matrix to form the burnable poison rod.

[0014] Optionally, the Er2O3 weight percentage in the burnable poison rod is 12.0%.

[0015] Optionally, the 235U enrichment in the burnable poison rods is the same as that of the fuel pellets.

[0016] According to another aspect of the present invention, a pressurized water reactor core with a first cycle of 18 months is provided, which has a fully ceramic microcapsule encapsulated fuel assembly and is loaded by the method described above.

[0017] Beneficial effects:

[0018] 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 40% to 4400MW without changing the core size, compared with the use of rod-shaped fuel, and the first cycle life reaches 18 months, thereby significantly improving the safety and economy of the reactor.

[0019] Moreover, compared with the rod-shaped UO2-Zr alloy fuel commonly used in existing pressurized water reactors, the fully ceramic microcapsule-encapsulated fuel has better fission product containment capabilities due to its coating design features, which can significantly reduce the possibility of large-scale releases under severe accidents and the need for off-site emergencies. The pressurized water reactor uses fully ceramic microcapsule-encapsulated fuel assemblies, which is conducive to the simplification of nuclear power plant equipment systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a pressurized water reactor core with a first cycle of 18 months using a fully ceramic microcapsule encapsulated fuel assembly according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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 is only 12-16 months, and there are problems such as poor economy and disadvantageous core safety, the present invention discloses a method for loading a pressurized water reactor core of the first cycle of 18 months using a fully ceramic microcapsule encapsulated fuel assembly. The core is composed of 177 groups of fully ceramic microcapsule encapsulated fuel assemblies, and each fully ceramic microcapsule encapsulated fuel assembly is divided into three zones for loading according to the enrichment degree. The enrichment degree of the fully ceramic microcapsule encapsulated fuel assemblies in the three zones is controlled within the range of 8%-10%, and each group of fully ceramic microcapsule encapsulated fuel assemblies is provided with 12 combustible poison rods, wherein:

[0025] Placing the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree in the outer area of ​​the core, and a total of 72 groups of the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree;

[0026] Arrange all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment in the middle area of ​​the core, and there are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment;

[0027] The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core, and there are 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment.

[0028] Correspondingly, the present invention also discloses a pressurized water reactor core with a first cycle of 18 months and a fully ceramic microcapsule-encapsulated fuel assembly, which is loaded by the method described above.

[0029] 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 40% to 4400MW without changing the core size, compared with the use of rod-shaped fuel, and the first cycle life reaches 18 months, thereby significantly improving the safety and economy of the reactor.

[0030] Example 1

[0031] This embodiment discloses a method for loading the core of a pressurized water reactor with a first cycle of 18 months of all-ceramic microcapsule encapsulated fuel assemblies, which can be used for a pressurized water reactor core with a reactor output thermal power of 4400MW. The core is composed of 177 groups of all-ceramic microcapsule encapsulated fuel assemblies. Under the core power of this embodiment, in order to make the first cycle core length reach 18 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.

[0032] In this embodiment, each all-ceramic microcapsule encapsulated fuel assembly is loaded into three zones according to the enrichment degree. The enrichment degree of the all-ceramic microcapsule encapsulated fuel assembly in the three zones is controlled within the range of 8% to 10%, and each group of all-ceramic microcapsule encapsulated fuel assemblies is provided with 12 combustible poison rods, of which:

[0033] Placing the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree in the outer area of ​​the core, and a total of 72 groups of the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree;

[0034] Arrange all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment in the middle area of ​​the core, and there are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment;

[0035] The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core, and there are 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment.

[0036] In some embodiments, the enrichment of the all-ceramic microencapsulated fuel assembly in the three zones is 8%, 9% and 10%, respectively, wherein:

[0037] 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%;

[0038] 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 in this embodiment;

[0039] The all-ceramic microcapsule encapsulated fuel assemblies with a relatively low enrichment of 9% are arranged in the middle area of ​​the core, and there are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies with an enrichment of 9%;

[0040] The above arrangement and quantity of the all-ceramic microcapsule encapsulated fuel assembly with 9% 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 in this embodiment;

[0041] The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment of 8% are arranged in the inner area of ​​the core, and there are a total of 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 8%.

[0042] The above arrangement and quantity of the all-ceramic microcapsule encapsulated fuel assembly with an enrichment degree of 8% 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 in this embodiment;

[0043] Table 1

[0044]

[0045]

[0046] Specifically, the height of the core active section is 365.76 cm, and the size of the all-ceramic microcapsule encapsulated fuel assembly is 12 inches. The all-ceramic microcapsule encapsulated fuel assembly includes a number of fuel rods, guide tubes and instrument tubes. In this embodiment, the all-ceramic microcapsule encapsulated fuel assembly includes 160 fuel rods, 8 guide tubes and 1 instrument tube. The fuel rods in each all-ceramic microcapsule encapsulated 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. The fuel particles are composed of a fuel core and a cladding layer. The fuel cladding layer has a very good fission product containment capacity and does not produce hydrogen. It can not only improve the safety of the fuel under accident conditions, but also facilitate the simplification of the equipment system of the nuclear power plant and improve the economy of the reactor.

[0047] In some embodiments, 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.

[0048] In some embodiments, the weight percentage of Er2O3 in the burnable poison rod is 12.0%, which can be beneficial to controlling the flattening of the core reactivity distribution and is beneficial to core safety. In addition, the 12% content of burnable poison is just right for the core. It will not be too much to cause poison penalty, nor will it be insufficient to cause poor core power flattening effect and Fdh exceeding the limit.

[0049] 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.

[0050] This embodiment also discloses a pressurized water reactor core with a first cycle of 18 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.

[0051] Compared with the prior art, the method for loading the core of a pressurized water reactor with a first cycle of 18 months using all-ceramic microcapsule-encapsulated fuel assemblies in this embodiment can ensure that the core power of a pressurized water reactor core composed of 177 fuel assemblies is increased by 40% to 4400MW compared with the use of traditional rod-shaped fuel (i.e., the UO2 core block is in the shape of a round rod with a cladding on the outside) without changing the core's external size. The first cycle life span reaches 18 months, and the safety and economy of the reactor are significantly improved.

[0052] Moreover, compared with the rod-shaped UO2-Zr alloy fuel commonly used in existing pressurized water reactors, the fully ceramic microcapsule-encapsulated fuel has better fission product containment capabilities due to its coating design features, which can significantly reduce the possibility of large-scale releases under severe accidents and the need for off-site emergencies. The pressurized water reactor uses fully ceramic microcapsule-encapsulated fuel assemblies, which is conducive to the simplification of nuclear power plant equipment systems and can improve the economy of the reactor.

[0053] Example 2

[0054] This embodiment discloses a method for loading a pressurized water reactor core with a first cycle of 18 months of all-ceramic microcapsule encapsulated fuel assemblies, which is used for a pressurized water reactor core with a reactor output thermal power of 4400MW. The method is basically the same as the method described in Example 1, except that:

[0055] like Figure 1 As shown, the horizontal coordinates are arranged from right to left by AR, and the vertical coordinates are arranged from top to bottom by 1-15. The method includes:

[0056] 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;

[0057] Arrange 32 sets of all-ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 9% and 12 burnable poison rods 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;

[0058] K1, J1, H1, G1, F1, M2, L2, K2, J2, G2, F2, E2, D2, N3, M3, L3, E3, D3, C3, P4, N4, C4, B4, P5 , N5, C5, B5, R6, P6, B6, A6, R7, P7, B7, A7, R8, A8, R9, P9, B9, A9, R10, P10, B10, A10, P11 72 sets of fully ceramic microcapsule-encapsulated fuel assemblies with an enrichment of 10% and containing 12 burnable poison rods are arranged in positions N11, C11, B11, P12, N12, C12, B12, N13, M13, L13, E13, D13, C13, M14, L14, K14, J14, G14, F14, E14, D14, K15, J15, H15, G15, and F15.

[0059] It should be noted that Figure 1 A combination of letters and numbers is used to indicate the position of the all-ceramic microcapsule encapsulated fuel assembly in the core. For example, H3 indicates that the position of the fuel assembly in the core is H 3.

[0060] This embodiment also discloses a pressurized water reactor core with a first cycle of 18 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.

[0061] After calculation, the main parameters of the first cycle of the pressurized water reactor core of this embodiment are as shown in Table 2.

[0062] Table 2

[0063] Parameter name First cycle Cycle length (MWd / tU) 30594 Cycle length (EFPD) 490 Maximum nuclear enthalpy rise factor 1.450 Maximum hot spot factor 2.011 Critical boron concentration (ppm) 1325 Moderator temperature coefficient (pcm / ℃) -0.329 Maximum fuel consumption of components (MWd / tU) 36160

[0064] 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.

[0065] Furthermore, it can be determined that the first cycle 18-month pressurized water reactor core loading method using all-ceramic microcapsule encapsulated fuel assemblies of this embodiment can apply all-ceramic microcapsule encapsulated fuel to a pressurized water reactor core of 177 assemblies without changing the core size. The core power is increased by 40% compared to when rod-shaped fuel is used, and the first cycle life length reaches 18 months.

[0066] 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 using all-ceramic microcapsules to encapsulate fuel assemblies for the first 18 months of the cycle, characterized in that: The core consists of 177 groups of all-ceramic microcapsule encapsulated fuel assemblies, which are loaded into three zones according to their enrichment. The enrichment of the all-ceramic microcapsule encapsulated fuel assemblies in the three zones is controlled within the range of 8% to 10%, and each group of all-ceramic microcapsule encapsulated fuel assemblies is equipped with 12 burnable poison rods, including: Placing the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree in the outer area of ​​the core, and a total of 72 groups of the fully ceramic microcapsule-encapsulated fuel assembly with the highest enrichment degree; Arrange all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment in the middle area of ​​the core, and there are 32 groups of all-ceramic microcapsule encapsulated fuel assemblies with relatively low enrichment; The fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner area of ​​the core, and there are 73 groups of fully ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment.

2. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first cycle of 18 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: The fully ceramic microcapsule-encapsulated fuel assembly with an enrichment level of 10% is placed outside 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 cycle of 18 months according to claim 1 or 2, 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.

4. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first cycle of 18 months according to claim 3, characterized in that: The weight percentage of Er2O3 in the burnable poison rod is 12.0%.

5. The method for loading the core of a pressurized water reactor using all-ceramic microcapsule encapsulated fuel assemblies for the first 18 months of the cycle 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.

6. A pressurized water reactor core with a first cycle of 18 months using all-ceramic microcapsule encapsulated fuel assemblies, characterized in that: The method according to any one of claims 1 to 5 is used for loading.

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