First cycle 18 month pressurized water reactor core for a 4000mw pressurized water reactor and method of loading same

Abstract

This invention discloses a pressurized water reactor core and its loading method for the first 18 months of a 4000MW pressurized water reactor. The core consists of 177 annular fuel assemblies, each with an enrichment degree of 4.1%, 4.25%, or 4.45%. Specifically, the annular fuel assemblies with the highest enrichment degree of 4.45% are placed in the outer region of the core, and there are 88 annular fuel assemblies with an enrichment degree of 4.25%. The annular fuel assemblies with relatively lower enrichment degrees of 4.25% and 4.1% are arranged in a checkerboard pattern in the inner region of the core, with 68 annular fuel assemblies with an enrichment degree of 4.25% and 21 annular fuel assemblies with an enrichment degree of 4.1%. This invention can ensure that, without changing the core size, the pressurized water reactor core consisting of 177 fuel assemblies can achieve a 25% increase in core power compared to using rod fuel, reaching 4000MW, and a first cycle life of 18 months, thereby significantly improving the core's economic efficiency.

Description

Technical Field

[0001] This invention belongs to the field of nuclear engineering technology, specifically relating to a 4000MW pressurized water reactor core for the first 18-month cycle and its loading method. Background Technology

[0002] Currently, pressurized water reactor cores, consisting of 177 fuel assemblies, use 12-foot rod fuel assemblies. The reactor output thermal power is typically 3050~3180MW, the first cycle core life is 12~16 months, the core power is relatively low, the core refueling cycle is short, and the economic efficiency is poor.

[0003] Compared to the aforementioned rod-shaped fuel assemblies, annular fuel can simultaneously cool the fuel pellets through both internal and external channels. This reduces the fuel's thermal conductivity thickness and increases its heat transfer area, lowering the peak pellet temperature and improving core safety. Furthermore, using annular fuel can increase the pressurized water reactor core power density by 20% to 50%, improving the economics of nuclear power plants. However, with the increase in reactor power, under current uranium loading conditions, the core refueling cycle will shorten, potentially failing to meet the 12-month refueling requirement, leading to insufficient economic viability after operation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the existing technology by providing a pressurized water reactor core with a first cycle of 18 months and its loading method for a 4000MW pressurized water reactor. This method can ensure that the pressurized water reactor core composed of 177 fuel assemblies can achieve a 25% increase in core power to 4000MW compared to the use of rod fuel, without changing the core size, and achieve a first cycle life of 18 months, thereby significantly improving economic efficiency.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is: According to one aspect of the present invention, a method for loading the core of a 4000MW pressurized water reactor during its first 18-month cycle is provided. The core consists of 177 annular fuel assemblies, each with an enrichment of 4.1%, 4.25%, or 4.45%, wherein: The annular fuel assemblies with the highest enrichment of 4.45% were placed in the outer region of the reactor core, with a total of 88 annular fuel assemblies having an enrichment of 4.45%. The annular fuel assemblies with a relatively low enrichment of 4.25% and the annular fuel assemblies with an enrichment of 4.1% were arranged in a checkerboard pattern in the inner region of the reactor core. There were 68 annular fuel assemblies with an enrichment of 4.25% and 21 annular fuel assemblies with an enrichment of 4.1%.

[0006] Optionally, some of the annular fuel assemblies contain combustible poison rods, and the number of combustible poison rods in each annular fuel assembly is 4, 8 or 12.

[0007] Optionally, the combustible poison rod is a gadolinium-loaded fuel rod with a Gd2O3 weight percentage of 8.0%.

[0008] Optionally, in gadolinium-loaded fuel rods 235 The U enrichment level was 2.5%.

[0009] Optionally, there are 40 annular fuel assemblies with an enrichment of 4.45% and containing no combustible poison rods; 16 annular fuel assemblies with an enrichment of 4.45% and containing 4 combustible poison rods; 20 annular fuel assemblies with an enrichment of 4.45% and containing 8 combustible poison rods; and 12 annular fuel assemblies with an enrichment of 4.45% and containing 12 combustible poison rods.

[0010] Optionally, there are 4 sets of annular fuel assemblies with an enrichment of 4.25% and containing no combustible poison rods; 24 sets of annular fuel assemblies with an enrichment of 4.25% and containing 4 combustible poison rods; and 40 sets of annular fuel assemblies with an enrichment of 4.25% and containing 12 combustible poison rods.

[0011] Optionally, there are 12 annular fuel assemblies with an enrichment of 4.1% and containing 8 combustible poison rods; or 9 annular fuel assemblies with an enrichment of 4.1% and containing 12 combustible poison rods.

[0012] According to another aspect of the present invention, a pressurized water reactor core for the first 18-month cycle of a 4000MW pressurized water reactor is provided, which is loaded using the method described above. Beneficial effects

[0013] The present invention relates to a 4000MW pressurized water reactor (PWR) core with an 18-month first-cycle lifespan and its loading method. Compared with existing technologies, this invention ensures that the PWR core, composed of 177 fuel assemblies, achieves a 25% increase in core power (4000MW) and an 18-month first-cycle lifespan without altering the core's external dimensions, by using annular fuel assemblies. This significantly improves core economics. Furthermore, the annular fuel assemblies allow for simultaneous cooling of the fuel pellets through both internal and external channels, reducing fuel thermal conductivity thickness, increasing heat transfer area, lowering peak pellet temperature, and consequently significantly enhancing core safety. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the core structure of a 4000MW pressurized water reactor during its first 18-month cycle, according to an embodiment of the present invention. Detailed Implementation

[0015] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0016] In the description of this invention, it should be noted that the terms "above" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience and simplification of the description and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0018] To address the issues of low core power, short refueling cycles, and poor economic efficiency in existing pressurized water reactors (PWRs) with 177 fuel assemblies, where the core output thermal power is only 3050-3180 MW and the first-cycle core lifespan is 12-16 months, this invention discloses a core loading method for a 4000 MW PWR with a first-cycle lifespan of 18 months. The core consists of 177 annular fuel assemblies, with each annular fuel assembly having an enrichment level of 4.1%, 4.25%, or 4.45%. The annular fuel assemblies with the highest enrichment of 4.45% were placed in the outer region of the reactor core, with a total of 88 annular fuel assemblies having an enrichment of 4.45%. The annular fuel assemblies with a relatively low enrichment of 4.25% and the annular fuel assemblies with an enrichment of 4.1% were arranged in a checkerboard pattern in the inner region of the reactor core. There were 68 annular fuel assemblies with an enrichment of 4.25% and 21 annular fuel assemblies with an enrichment of 4.1%.

[0019] Accordingly, the present invention also discloses a pressurized water reactor core for the first 18-month cycle of a 4000MW pressurized water reactor, which is loaded using the method described above.

[0020] Compared with existing technologies, this invention can ensure that the pressurized water reactor core, composed of 177 fuel assemblies, can achieve a 25% increase in core power to 4000MW when using annular fuel assemblies without changing the core's size, and achieve a first cycle life of 18 months, thereby significantly improving the core's economic efficiency. Example 1

[0021] This embodiment discloses a core loading method for a 4000MW pressurized water reactor during its first 18-month cycle. The core consists of 177 annular fuel assemblies, with each annular fuel assembly having an enrichment level of 4.1%, 4.25%, or 4.45%. The annular fuel assemblies with the highest enrichment of 4.45% were placed in the outer region of the reactor core, with a total of 88 annular fuel assemblies having an enrichment of 4.45%. The annular fuel assemblies with a relatively low enrichment of 4.25% and the annular fuel assemblies with an enrichment of 4.1% were arranged in a checkerboard pattern in the inner region of the reactor core. There were 68 annular fuel assemblies with an enrichment of 4.25% and 21 annular fuel assemblies with an enrichment of 4.1%.

[0022] Specifically, the height of the active section of the reactor core is 365.76 cm, and the size of the annular fuel assembly is 12 feet. The annular fuel assembly includes several fuel rods, guide tubes, and instrument tubes. In this embodiment, the annular fuel assembly includes 160 fuel rods, 8 guide tubes, and 1 instrument tube. The fuel rods within each annular fuel assembly are arranged in a 13×13 configuration.

[0023] In some embodiments, a portion of the annular fuel assembly contains combustible poison rods, and the number of combustible poison rods in each annular fuel assembly is 4, 8, or 12.

[0024] In some more specific embodiments, as shown in Table 1, there are 40 sets of annular fuel assemblies with an enrichment of 4.45% and containing no combustible poison rods; 16 sets of annular fuel assemblies with an enrichment of 4.45% and containing 4 combustible poison rods; 20 sets of annular fuel assemblies with an enrichment of 4.45% and containing 8 combustible poison rods; and 12 sets of annular fuel assemblies with an enrichment of 4.45% and containing 12 combustible poison rods.

[0025] There were 4 sets of annular fuel assemblies with an enrichment of 4.25% and no combustible poison rods; 24 sets of annular fuel assemblies with an enrichment of 4.25% and containing 4 combustible poison rods; and 40 sets of annular fuel assemblies with an enrichment of 4.25% and containing 12 combustible poison rods.

[0026] There are 12 annular fuel assemblies with an enrichment of 4.1% and containing 8 combustible poison rods; and 9 annular fuel assemblies with an enrichment of 4.1% and containing 12 combustible poison rods.

[0027] Table 1

[0028] In some implementations, the combustible poison rods are gadolinium-loaded fuel rods with a Gd2O3 weight percentage of 8.0%. This allows for optimal core power flattening, which is beneficial for core safety. Furthermore, the release of combustible poison at this ratio throughout the entire lifespan can best match changes in core reactivity, thus enabling better control of reactivity.

[0029] In some embodiments, the gadolinium-loaded fuel rods 235 A U enrichment level of 2.5% optimizes the power flattening of the reactor core, which is beneficial for core safety. Furthermore, at this level, the release of combustible poisons throughout the reactor's lifespan best matches changes in core reactivity, allowing for better control of reactivity.

[0030] This embodiment also discloses a 4000MW pressurized water reactor core with a first cycle of 18 months obtained by the above method. Its specific structure is as described in the above method and will not be repeated here.

[0031] The pressurized water reactor (PWR) core loading method for the 4000MW PWR in this embodiment, with a first-cycle lifespan of 18 months, compared to existing technologies, ensures that the PWR core, composed of 177 fuel assemblies, achieves a 25% increase in core power (4000MW) and a first-cycle lifespan of 18 months by using annular fuel assemblies, without altering the core's external size. This significantly improves core economics. Furthermore, the annular fuel assemblies allow for simultaneous cooling of the fuel pellets through both internal and external channels, reducing fuel thermal conductivity thickness, increasing heat transfer area, lowering peak pellet temperature, and consequently significantly enhancing core safety. Example 2

[0032] This embodiment discloses a core loading method for a 4000MW pressurized water reactor during its first 18-month cycle. It is essentially the same as the method described in Embodiment 1, except that: like Figure 1 As shown, the x-axis is arranged from right to left as AR, and the y-axis is arranged from top to bottom as 1-15. This method includes: Twelve annular fuel assemblies with an enrichment of 4.1% and containing eight gadolinium-loaded poison rods are arranged at positions H4, J5, G5, L7, E7, M8, D8, L9, E9, J11, G11, and H12 in the reactor core. Nine annular fuel assemblies with an enrichment of 4.1% and containing 12 gadolinium poison rods are arranged at positions H6, J7, G7, K8, H8, F8, J9, G9, and H10 in the reactor core. Twenty-four annular fuel assemblies, each with an enrichment of 4.25% and containing four gadolinium-loaded rods, are arranged at positions H5, L8, E8, H11, J3, G3, K4, F4, L5, E5, M6, K6, F6, D6, N7, C7, N9, C9, M10, K10, F10, D10, L11, E11, K12, F12, J13, and G13 in the reactor core. Forty annular fuel assemblies, each enriched to 4.25% and containing 12 gadolinium-loaded rods, are arranged at positions H3, L4, J4, G4, E4, M5, K5, F5, D5, L6, J6, G6, E6, M7, K7, H7, F7, D7, N8, J8, G8, C8, M9, K9, H9, F9, D9, L10, J10, G10, E10, M11, K11, F11, D11, L12, J12, G12, E12, and H13 in the reactor core. Forty annular fuel assemblies with an enrichment of 4.45% and without gadolinium poison rods are arranged at positions K1, J1, H1, G1, F1, M2, L2, E2, D2, N3, C3, P4, B4, P5, B5, R6, A6, R7, A7, R8, A8, R9, A9, R10, A10, P11, B11, P12, B12, N13, C13, M14, L14, E14, D14, K15, J15, H15, G15, and F15 in the reactor core. Sixteen annular fuel assemblies with an enrichment of 4.45% and containing four gadolinium-loaded rods are arranged at positions K2, F2, M3, D3, N4, C4, P6, B6, P10, B10, N12, C12, M13, D13, K14, and F14 in the reactor core. Twenty annular fuel assemblies with an enrichment of 4.45% and containing eight gadolinium-loaded rods are arranged at positions J2, H2, G2, L3, E3, N5, C5, P7, B7, P8, B8, P9, B9, N11, C11, L13, E13, J14, H14, and G14 in the reactor core. Twelve annular fuel assemblies with an enrichment of 4.45% and containing 12 gadolinium poison rods are arranged at positions K3, F3, M4, D4, N6, C6, N10, C10, M12, D12, K13, and F13 in the reactor core.

[0033] It should be noted that, Figure 1 The position of a fuel assembly in the reactor core is indicated by a combination of letters and numbers. For example, H4 indicates that the fuel assembly is located at position H4 in the reactor core.

[0034] This embodiment also discloses a 4000MW pressurized water reactor core with a first cycle of 18 months obtained by the above method. Its specific structure is as described in the above method and will not be repeated here.

[0035] The main parameters of the first cycle of the pressurized water reactor core in this embodiment are shown in Table 2 after calculation.

[0036] Table 2

[0037] Currently, there are no clear safety guidelines for the core parameters of pressurized water reactors using annular fuel assemblies. Referring to the existing design guidelines for pressurized water reactor cores with 177 assemblies, the core design guidelines in this embodiment are as follows: 1) Core fuel assemblies 235 U enrichment ≤ 4.95%; 2) The design criteria are: maximum nuclear enthalpy rise factor ≤ 1.48 and maximum hot spot factor ≤ 2.50. 3) The temperature coefficient of the reactor core moderator is ≤0 pcm / ℃; 4) Maximum fuel consumption of the component ≤ 52000MWd / tU.

[0038] Based on the calculation results of the main core parameters in Table 2, it can be determined that the core parameters meet the design criteria requirements.

[0039] Furthermore, a core loading method for a 4000MW pressurized water reactor with an initial cycle life of 18 months can be determined. This method allows the application of annular fuel to a 177-assembly pressurized water reactor core without changing the core's external shape and size. The core power is increased by 25% compared to using rod fuel, and the initial cycle life reaches 18 months.

[0040] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled 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 of loading a pressurized water reactor core for a first cycle of 18 months for a power 4000 MW pressurized water reactor, characterized in that, The reactor core consists of 177 annular fuel assemblies, with each annular fuel assembly having an enrichment level of 4.1%, 4.25%, or 4.45%, respectively. The annular fuel assemblies with the highest enrichment of 4.45% were placed in the outer region of the reactor core, with a total of 88 annular fuel assemblies having an enrichment of 4.45%. The annular fuel assemblies with a relatively low enrichment of 4.25% and the annular fuel assemblies with an enrichment of 4.1% are arranged in a checkerboard pattern in the inner region of the reactor core. There are 68 annular fuel assemblies with an enrichment of 4.25% and 21 annular fuel assemblies with an enrichment of 4.1%. Among them, some annular fuel assemblies contain combustible poison rods, and the number of combustible poison rods in annular fuel assemblies with an enrichment of 4.45% is 0, 4, 8 or 12, the number of combustible poison rods in annular fuel assemblies with an enrichment of 4.25% is 0, 4 or 12, and the number of combustible poison rods in annular fuel assemblies with an enrichment of 4.1% is 8 or 12.

2. The power 4000 MW pressurized water first cycle 18 months pressurized water core loading method of claim 1, wherein, The combustible poison rods use gadolinium-loaded fuel rods, with a Gd2O3 weight percentage of 8.0% in the gadolinium-loaded fuel rods.

3. The power 4000 MW pressurized water first cycle 18 months pressurized water core loading method of claim 2, wherein, In gadolinium loaded fuel rods 235 U enrichment is 2.5%.

4. The method for loading the core of a 4000MW pressurized water reactor during its first 18-month cycle according to claim 1, characterized in that, Forty sets of annular fuel assemblies with an enrichment level of 4.45% and containing no combustible poison rods; There are 16 sets of annular fuel assemblies with an enrichment of 4.45% and containing 4 combustible poison rods; There are 20 sets of annular fuel assemblies with an enrichment of 4.45% and containing 8 combustible poison rods; There are 12 sets of annular fuel assemblies with an enrichment of 4.45% and containing 12 combustible poison rods.

5. The method for loading the core of a 4000MW pressurized water reactor during its first 18-month cycle according to claim 1, characterized in that, Four sets of annular fuel assemblies with an enrichment level of 4.25% and containing no combustible poison rods were used. There are 24 sets of annular fuel assemblies with an enrichment of 4.25% and containing 4 combustible poison rods; There are 40 annular fuel assemblies with an enrichment level of 4.25% and containing 12 combustible poison rods.

6. The method for loading the core of a 4000MW pressurized water reactor during its first 18-month cycle according to claim 1, characterized in that, There are 12 sets of annular fuel assemblies with an enrichment of 4.1% and containing 8 combustible poison rods; There are nine annular fuel assemblies with an enrichment level of 4.1% and containing 12 combustible poison rods.

7. A first cycle 18 month pressurized water reactor core for a power 4000 MW pressurized water reactor, characterized in that, It is loaded using the method described in any one of claims 1-6.

Images