A pressurized water reactor core employing all-ceramic microencapsulated fuel assemblies for the first 18 months of a cycle and a method of loading the same

Abstract

The application discloses a full-ceramic microcapsule packaged fuel assembly first-cycle 18-month pressurized water reactor core and a loading method thereof. The core is composed of 177 full-ceramic microcapsule packaged fuel assemblies. The assemblies are loaded according to the enrichment degree and are divided into three zones. The enrichment degree of the assemblies in the three zones is controlled within the range of 8% to 10%. Each of the assemblies is provided with 12 burnable poison rods. The assembly with the highest enrichment degree is arranged in the outer zone of the core, and there are 72 assemblies with the highest enrichment degree. The assembly with relatively low enrichment degree is arranged in the middle zone of the core, and there are 32 assemblies with relatively low enrichment degree. The assembly with the lowest enrichment degree is arranged in the inner zone of the core, and there are 73 assemblies with the lowest enrichment degree. The application can ensure that the pressurized water reactor core composed of 177 fuel assemblies can improve the core power by 40% compared with the rod-shaped fuel under the premise of not changing the size of the core shape, and the core power can reach 4400MW. The first-cycle service life length reaches 18 months, and the nuclear fuel utilization rate and the economy are obviously improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nuclear engineering, and particularly relates to a first-cycle 18-month pressurized water reactor core adopting full-ceramic microcapsule-encapsulated fuel assemblies and a loading method thereof. BACKGROUND

[0002] At present, a pressurized water reactor core composed of 177 fuel assemblies adopts 12-foot rod-shaped fuel assemblies, the reactor output thermal power is 3050-3180 MW, the first-cycle core service life length is only 12-16 months, the core refueling period is short, and the economy is poor. Moreover, since the fuel assemblies of the above-mentioned pressurized water reactor core adopt the design of "UO2 pellets-Zr alloy cladding", there is a risk of hydrogen explosion under accident conditions, which is not conducive to the safety of the reactor. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a first-cycle 18-month pressurized water reactor core adopting full-ceramic microcapsule-encapsulated fuel assemblies and a loading method thereof, which can ensure that the pressurized water reactor core composed of 177 fuel assemblies has a core power increased by 40% compared with the rod-shaped fuel, reaches 4400 MW, and has a first-cycle service life length of 18 months, so that the safety and economy of the reactor are obviously improved.

[0004] The technical scheme for solving the above technical problem of the present application is:

[0005] According to one aspect of the present application, a first-cycle 18-month pressurized water reactor core loading method adopting full-ceramic microcapsule-encapsulated fuel assemblies is provided, the core is composed of 177 full-ceramic microcapsule-encapsulated fuel assemblies, each full-ceramic microcapsule-encapsulated fuel assembly is loaded according to the enrichment degree size into three zones, the enrichment degrees of the full-ceramic microcapsule-encapsulated fuel assemblies in the three zones are controlled within the range of 8%-10%, and 12 burnable poison rods are arranged in each full-ceramic microcapsule-encapsulated fuel assembly, wherein:

[0006] the full-ceramic microcapsule-encapsulated fuel assemblies with the highest enrichment degree are arranged in the outer zone of the core, and there are 72 full-ceramic microcapsule-encapsulated fuel assemblies with the highest enrichment degree;

[0007] the full-ceramic microcapsule-encapsulated fuel assemblies with relatively low enrichment degree are arranged in the middle zone of the core, and there are 32 full-ceramic microcapsule-encapsulated fuel assemblies with relatively low enrichment degree;

[0008] the full-ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment degree are arranged in the inner zone of the core, and there are 73 full-ceramic microcapsule-encapsulated fuel assemblies with the lowest enrichment degree.

[0009] Optionally, the enrichment levels of the all-ceramic microencapsulated fuel assemblies in the three regions are 8%, 9%, and 10%, respectively, where:

[0010] The fuel assembly, encapsulated in all-ceramic microcapsules with an enrichment level of 10%, was placed in the outer region of the reactor core.

[0011] All-ceramic microencapsulated fuel assemblies with an enrichment level of 9% were arranged in the middle region of the reactor core;

[0012] Fuel assemblies encapsulated in all-ceramic microcapsules with an enrichment level of 8% were arranged in the inner region of the reactor core.

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

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

[0015] Optionally, the enrichment of 235U in the combustible poison rods can be the same as that in the fuel pellets.

[0016] According to another aspect of the present invention, a pressurized water reactor core for the first 18-month cycle of a fuel assembly encapsulated in all-ceramic microcapsules is provided, which is loaded using the method described above.

[0017] Beneficial effects:

[0018] Compared to existing technologies, this invention can ensure that the core power of a pressurized water reactor composed of 177 fuel assemblies is increased by 40% compared to the use of rod fuel, reaching 4400MW, without changing the core size, and the first cycle life reaches 18 months, significantly improving the safety and economy of the reactor.

[0019] Furthermore, compared to the existing pressurized water reactors that generally use rod-shaped UO2-Zr alloy fuel, the all-ceramic microencapsulated fuel has a better fission product containment capacity due to its coating layer design characteristics. This can significantly reduce the possibility of large-scale release in severe accidents and the need for off-site emergency response. The use of all-ceramic microencapsulated fuel assemblies in pressurized water reactors is beneficial to the simplification of nuclear power plant equipment systems. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the core structure of a pressurized water reactor with fuel assemblies encapsulated in all ceramic microcapsules, representing an embodiment of the present invention, for the first 18-month pressurized water reactor cycle. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Addressing the issues of poor economic efficiency and compromised core safety in existing pressurized water reactor (PWR) cores composed of 177 fuel assemblies (output thermal power of only 3050–3180 MW and first-cycle core life of only 12–16 months), this invention discloses a method for loading a PWR core with a first-cycle life of 18 months using all-ceramic microencapsulated fuel assemblies. The core consists of 177 all-ceramic microencapsulated fuel assemblies, which are loaded into three zones based on their enrichment levels. The enrichment level of the all-ceramic microencapsulated fuel assemblies in the three zones is controlled within the range of 8%–10%. Each all-ceramic microencapsulated fuel assembly contains 12 combustible poison rods.

[0025] The fuel assemblies with the highest enrichment of all-ceramic microcapsules are placed in the outer region of the reactor core, and there are a total of 72 sets of the fuel assemblies with the highest enrichment of all-ceramic microcapsules.

[0026] The fuel assemblies with relatively low enrichment are arranged in the middle region of the reactor core, and there are a total of 32 sets of the fuel assemblies with relatively low enrichment.

[0027] The fuel assemblies with the lowest enrichment level, all-ceramic microcapsule encapsulated fuel assemblies, are arranged in the inner region of the reactor core, and there are a total of 73 sets of the fuel assemblies with the lowest enrichment level, all-ceramic microcapsule encapsulated fuel assemblies.

[0028] Accordingly, the present invention also discloses a pressurized water reactor core for the first 18-month cycle of a fuel assembly encapsulated in all ceramic microcapsules, which is loaded using the method described above.

[0029] Compared to existing technologies, this invention can ensure that the core power of a pressurized water reactor composed of 177 fuel assemblies is increased by 40% compared to the use of rod fuel, reaching 4400MW, without changing the core size, and the first cycle life reaches 18 months, significantly improving the safety and economy of the reactor.

[0030] Example 1

[0031] This embodiment discloses a method for loading a pressurized water reactor core for the first cycle of 18 months using all-ceramic microencapsulated fuel assemblies. This method can be used for pressurized water reactor cores with a reactor output thermal power of 4400MW. The core consists of 177 all-ceramic microencapsulated fuel assemblies. Under the core power of this embodiment, to achieve a first cycle core length of 18 months, and to avoid excessive enrichment leading to high fuel assembly costs and reduced core economics, the enrichment of the core fuel assemblies is controlled within the range of 8% to 10%. To control core reactivity, some fuel assemblies are equipped with several combustible poison rods. The combustible poison within these rods can introduce sufficiently high negative reactivity while effectively matching the decreasing reactivity due to burnup, thus achieving core reactivity control.

[0032] In this implementation scheme, the all-ceramic microcapsule-encapsulated fuel assemblies are loaded into three zones according to their enrichment levels. The enrichment levels of the all-ceramic microcapsule-encapsulated fuel assemblies in the three zones are controlled within the range of 8% to 10%, and each group of all-ceramic microcapsule-encapsulated fuel assemblies contains 12 combustible poison rods, wherein:

[0033] The fuel assemblies with the highest enrichment of all-ceramic microcapsules are placed in the outer region of the reactor core, and there are a total of 72 sets of the fuel assemblies with the highest enrichment of all-ceramic microcapsules.

[0034] The fuel assemblies with relatively low enrichment are arranged in the middle region of the reactor core, and there are a total of 32 sets of the fuel assemblies with relatively low enrichment.

[0035] The fuel assemblies with the lowest enrichment level, all-ceramic microcapsule encapsulated fuel assemblies, are arranged in the inner region of the reactor core, and there are a total of 73 sets of the fuel assemblies with the lowest enrichment level, all-ceramic microcapsule encapsulated fuel assemblies.

[0036] In some implementations, the enrichment levels of the all-ceramic microencapsulated fuel assembly in the three regions are 8%, 9%, and 10%, respectively, wherein:

[0037] The 10% of the most enriched all-ceramic microcapsule fuel assemblies were placed in the outer region of the reactor core, and as shown in Table 1, there were a total of 72 sets of all-ceramic microcapsule fuel assemblies with an enrichment of 10%.

[0038] The above arrangement and quantity of fuel assemblies encapsulated in all-ceramic microcapsules with a 10% enrichment level, as well as the arrangement and quantity of combustible poisons, are only one of the solutions that meet the requirements. Of course, there are other solutions, which will not be described in detail in this embodiment.

[0039] A total of 32 fuel assemblies with a 9% enrichment of all-ceramic microcapsules were arranged in the core region, with a relatively low enrichment of 9%.

[0040] The above arrangement and quantity of fuel assemblies encapsulated in all-ceramic microcapsules with a 9% enrichment level, as well as the arrangement and quantity of combustible poisons, are only one of the solutions that meet the requirements. Of course, there are other solutions, which will not be described in detail in this embodiment.

[0041] The fuel assemblies with the lowest enrichment of 8% were arranged in the inner core region, and a total of 73 sets of fuel assemblies with an enrichment of 8% were arranged in the inner core region.

[0042] The above arrangement and quantity of fuel assemblies encapsulated in all-ceramic microcapsules with an 8% enrichment level, as well as the arrangement and quantity of combustible poisons, are only one of the solutions that meet the requirements. Of course, there are other solutions, which will not be described in detail in this embodiment.

[0043] Table 1

[0044]

[0045]

[0046] Specifically, the height of the active section of the reactor core is 365.76 cm, and the size of the all-ceramic microencapsulated fuel assembly is 12 inches. The all-ceramic microencapsulated fuel assembly includes several fuel rods, guide tubes, and instrumentation tubes. In this embodiment, the all-ceramic microencapsulated fuel assembly includes 160 fuel rods, 8 guide tubes, and 1 instrumentation tube. The fuel rods within each all-ceramic microencapsulated fuel assembly are arranged in a 13×13 pattern. The fuel rods include several fuel pellets, which are formed by fuel particles dispersed in a SiC matrix. The fuel particles consist of a fuel core and a coating layer. The fuel coating layer has excellent fission product containment capacity and does not produce hydrogen, which not only improves fuel safety under accident conditions but also facilitates the simplification of nuclear power plant equipment systems and enhances reactor economics.

[0047] In some embodiments, the combustible poison rod uses Er2O3 as the combustible poison, and the fuel particles and the combustible poison are dispersed in the SiC matrix to form the combustible poison rod.

[0048] In some implementations, the Er2O3 weight percentage in the combustible poison rod is 12.0%, which is beneficial for controlling the distribution and flattening of core reactivity, thus contributing to core safety. Furthermore, the 12% content of combustible poison is just right for this core, neither too much leading to poison penalty nor too little resulting in poor core power flattening and Fdh exceeding the limit.

[0049] In some implementations, the enrichment degree of 235U in the combustible poison rods is the same as that in the fuel pellets, which is beneficial for obtaining combustible poison ingredients.

[0050] This embodiment also discloses a pressurized water reactor core with a first cycle of 18 months that uses the above method to encapsulate fuel assemblies in all-ceramic microcapsules. Its specific structure is as described in the above method and will not be repeated here.

[0051] The pressurized water reactor (PWR) core loading method for the first cycle of 18 months using all-ceramic microencapsulated fuel assemblies in this embodiment, compared with the prior art, can ensure that the PWR core composed of 177 fuel assemblies can achieve a core power of 40% higher than that using traditional rod-shaped fuel (i.e., UO2 pellets are round rods with an outer cladding) without changing the core size, reaching 4400MW. The first cycle life can reach 18 months, and the safety and economy of the reactor are significantly improved.

[0052] Furthermore, compared to the existing pressurized water reactors that generally use rod-shaped UO2-Zr alloy fuel, the all-ceramic microencapsulated fuel has a better fission product containment capacity due to its coating design characteristics. This can significantly reduce the possibility of large-scale release in severe accidents and the need for off-site emergency response. The use of all-ceramic microencapsulated fuel assemblies in pressurized water reactors is conducive to the simplification of nuclear power plant equipment systems and can improve the economics of the reactor.

[0053] Example 2

[0054] This embodiment discloses a method for loading a pressurized water reactor core for the first 18 months of operation of a fully ceramic microencapsulated fuel assembly. This method is used for a pressurized water reactor core with a reactor output thermal power of 4400MW. It is essentially the same as the method described in Embodiment 1, with the following differences:

[0055] like Figure 1 As shown, the axes are arranged from right to left in the order of AR, and the ordinates are arranged from top to bottom in the order of 1-15. This method includes:

[0056] In the reactor 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 9. The fuel assemblies consisting of 73 groups with an enrichment of 8% and containing 12 combustible poison rods are arranged in positions 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] Thirty-two sets of fully ceramic microcapsule-encapsulated fuel assemblies, each containing 12 combustible 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 in the reactor 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 A fuel assembly consisting of 72 groups of fully ceramic microcapsules with an enrichment of 10% and containing 12 combustible poison rods is arranged at 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 The location of the all-ceramic microencapsulated fuel assembly in the reactor core is indicated by a combination of letters and numbers. For example, H3 indicates that the fuel assembly is located at H3 in the reactor core.

[0060] This embodiment also discloses a pressurized water reactor core with a first cycle of 18 months for a fuel assembly encapsulated in all ceramic microcapsules using the above method. Its specific structure is as described in the above method and will not be repeated here.

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

[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 / °C) -0.329 Assembly maximum burnup value (MWd / tU) 36160

[0064] 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.

[0065] Furthermore, it can be determined that the pressurized water reactor core loading method of the first cycle of 18 months using fully ceramic microencapsulated fuel assemblies in this embodiment can apply fully ceramic microencapsulated fuel to the pressurized water reactor core of 177 assemblies without changing the core shape and size. The core power is increased by 40% compared with the use of rod fuel, and the first cycle life reaches 18 months.

[0066] 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 for loading a pressurized water reactor core with fuel assemblies encapsulated with all-ceramic microcapsules for a first cycle of 18 months, characterized in that, The core is composed of 177 groups of full-ceramic micro-encapsulated fuel assemblies, each group of full-ceramic micro-encapsulated fuel assemblies is loaded in three zones according to the enrichment, the enrichment of the full-ceramic micro-encapsulated fuel assemblies in the three zones is controlled in the range of 8% to 10%, and 12 burnable poison rods are arranged in each group of full-ceramic micro-encapsulated fuel assemblies, wherein: The full-ceramic micro-encapsulated fuel assemblies with the highest enrichment are arranged in the outer zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with the highest enrichment are 72 groups; The full-ceramic micro-encapsulated fuel assemblies with relatively low enrichment are arranged in the middle zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with relatively low enrichment are 32 groups; The full-ceramic micro-encapsulated fuel assemblies with the lowest enrichment are arranged in the inner zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with the lowest enrichment are 73 groups.

2. The method for loading the core of a pressurized water reactor with fuel assemblies encapsulated with all-ceramic microcapsules for the first cycle of 18 months according to claim 1, characterized in that, The enrichment of the full-ceramic micro-encapsulated fuel assemblies in the three zones is 8%, 9% and 10% respectively, wherein: The full-ceramic micro-encapsulated fuel assemblies with an enrichment of 10% are arranged in the outer zone of the core, The full-ceramic micro-encapsulated fuel assemblies with an enrichment of 9% are arranged in the middle zone of the core; The full-ceramic micro-encapsulated fuel assemblies with an enrichment of 8% are arranged in the inner zone of the core.

3. A method for loading the core of a pressurized water reactor with fuel assemblies encapsulated with all-ceramic microcapsules for the first cycle of 18 months according to claim 1 or 2, characterized in that, The burnable poison rod adopts 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.

4. The method for loading the core of a pressurized water reactor with fuel assemblies encapsulated with all-ceramic microcapsules 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 with fuel assemblies encapsulated with all-ceramic microcapsules for the first cycle of 18 months according to claim 1 or 2, characterized in that, The enrichment of 235U in the burnable poison rod is the same as the enrichment of the fuel pellets.

6. A full ceramic microencapsulated fuel assembly first cycle 18 month pressurized water reactor core, characterized in that, The loading is obtained by the method of any one of claims 1-5.

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