A pressurized water reactor core employing all-ceramic microencapsulated fuel assemblies for the first cycle of 24 months and a method of loading the same

Abstract

The application discloses a full-ceramic microcapsule packaged fuel assembly first-cycle 24-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 degrees of the assemblies in the three zones are controlled within the range of 8% to 10%. The assemblies with the highest enrichment degree are arranged in the outer zone of the core. The assemblies with the highest enrichment degree are 72 assemblies. The burnable poison rods in part of the assemblies are 8, and the burnable poison rods in another part of the assemblies are 12. The assemblies with relatively low enrichment degree are arranged in the middle zone of the core. The assemblies with relatively low enrichment degree are 32 assemblies, and the burnable poison rods in the assemblies are 12. The assemblies with the lowest enrichment degree are arranged in the inner zone of the core. The assemblies with the lowest enrichment degree are 73 assemblies, and the burnable poison rods in the assemblies are 12. The power of the core is increased by 15% compared with the power of the rod-shaped fuel, and can reach 3500MW. The first-cycle service life length reaches 24 months. The safety and economy of the core 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 24-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 is in a chessboard distribution, the reactor output heat power is usually 3050-3180 MW, the first cycle core service life is not more than 16 months, and the subsequent cycle service life is about 18 months, so the core reloading period is short and the economy is poor.

[0003] In addition, the fuel rods in the fuel assemblies of the pressurized water reactor core have UO2 pellets and Zr alloy cladding. Although the UO2 pellets have a high melting point, the thermal conductivity is low in a high-temperature and high-radiation environment, which will lead to a steeper temperature gradient and thermal stress, and aggravate the accident consequences in accident conditions. Although the Zr alloy cladding has a small thermal neutron capture cross section, the cladding temperature may be high enough to cause a violent zirconium-water reaction under high-temperature accident conditions, thereby generating a large amount of hydrogen, and even a hydrogen explosion may occur, causing a large amount of radioactive material to be released, and the core safety is low. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a first cycle 24-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 15% compared with the rod-shaped fuel, reaches 3500 MW, and has a first cycle service life of 24 months, thereby obviously improving the core safety and economy without changing the size of the core.

[0005] The technical solution of the present application to solve the above technical problem is:

[0006] According to one aspect of the present application, a first cycle 24-month pressurized water reactor core loading method adopting full ceramic microcapsule encapsulated fuel assemblies is provided, characterized in that the core is composed of 177 full ceramic microcapsule encapsulated fuel assemblies, each full ceramic microcapsule encapsulated fuel assembly is loaded in three zones according to the enrichment degree, and the enrichment degrees of the full ceramic microcapsule encapsulated fuel assemblies in the three zones are controlled in the range of 8%-10%, wherein:

[0007] the full ceramic microcapsule encapsulated fuel assemblies with the highest enrichment degree are placed in the outer zone of the core, and the full ceramic microcapsule encapsulated fuel assemblies in the outer zone of the core are 72 groups, wherein the number of burnable poison rods in part of the assemblies is 8, and the number of burnable poison rods in another part of the assemblies is 12;

[0008] The full-ceramic micro-encapsulated fuel assembly with relatively low enrichment is arranged in the middle zone of the core, and the full-ceramic micro-encapsulated fuel assembly in the middle zone of the core is 32 groups, and the number of the burnable poison rods in the assembly is 12;

[0009] The full-ceramic micro-encapsulated fuel assembly with the lowest enrichment is arranged in the inner zone of the core, and the full-ceramic micro-encapsulated fuel assembly in the inner zone of the core is 73 groups, and the number of the burnable poison rods in the assembly is 12.

[0010] Optionally, the enrichment of the full-ceramic micro-encapsulated fuel assemblies in the three zones is 8%, 9% and 10% respectively, wherein:

[0011] The full-ceramic micro-encapsulated fuel assembly with the enrichment of 10% is arranged in the outer zone of the core;

[0012] The full-ceramic micro-encapsulated fuel assembly with the enrichment of 9% is arranged in the middle zone of the core;

[0013] The full-ceramic micro-encapsulated fuel assembly with the enrichment of 8% is arranged in the inner zone of the core.

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

[0015] 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.

[0016] Optionally, the weight percentage of Er2O3 in the burnable poison rod is 12.0%.

[0017] Optionally, the enrichment of 235U in the burnable poison rod is the same as the enrichment of the fuel pellet.

[0018] According to another aspect of the present application, a 24-month primary cycle pressurized water reactor core of full-ceramic micro-encapsulated fuel assemblies is provided, which is obtained by using the above method.

[0019] Beneficial effects:

[0020] Compared with the prior art, the present application can ensure that the pressurized water reactor core composed of 177 fuel assemblies can increase the core power by 15% compared with the rod-shaped fuel under the premise of not changing the size of the core shape, and can reach 3500MW, the primary cycle service life length reaches 24 months, and the safety and economy of the core are obviously improved.

[0021] And, the full ceramic microcapsule encapsulated fuel has better fission product containment capacity due to the design features of the coating layer, has the significant advantages of high temperature resistance, corrosion resistance and no hydrogen production, can greatly reduce the possibility of large-scale release under severe accidents and the demand for off-site emergency, is beneficial to the simplification of nuclear power plant equipment systems and plays a crucial role in the improvement of economy. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of a 24-month primary cycle pressurized water reactor core adopting the full ceramic microcapsule encapsulated fuel assembly of the embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to enable a person skilled in the art to better understand the technical solutions of the present application, the technical solutions in the present application will be described in detail below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person skilled in the art without creative labor fall within the protection scope of the present application.

[0024] In the description of the present application, it should be noted that the terms "upper", "lower" and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience and simplification of description, and do not indicate or imply that the indicated device or element must be provided with a particular orientation, constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0025] In the description of the present application, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0026] In view of the problems of the pressurized water reactor core composed of 177 fuel assemblies in the prior art, such as the output thermal power of only 3050-3180MW, the primary cycle core service life not exceeding 16 months, the subsequent cycle being about 18 months, low core safety and poor economy, the present application discloses a primary cycle 24-month pressurized water reactor core loading method adopting full ceramic microcapsule encapsulated fuel assemblies. The core is composed of 177 full ceramic microcapsule encapsulated fuel assemblies. Each full ceramic microcapsule encapsulated fuel assembly is loaded in three zones according to the enrichment degree. The enrichment degrees of the full ceramic microcapsule encapsulated fuel assemblies in the three zones are controlled within the interval of 8%-10%, wherein:

[0027] The full-ceramic micro-encapsulated fuel assembly with the highest enrichment is arranged in the outer zone of the core, and the full-ceramic micro-encapsulated fuel assemblies in the outer zone of the core are 72 groups, wherein the number of the burnable poison rods in some assemblies is 8, and the number of the burnable poison rods in another part of the assemblies is 12;

[0028] The full-ceramic micro-encapsulated fuel assembly with relatively low enrichment is arranged in the middle zone of the core, and the full-ceramic micro-encapsulated fuel assemblies in the middle zone of the core are 32 groups, and the number of the burnable poison rods in the assemblies is 12;

[0029] The full-ceramic micro-encapsulated fuel assembly with the lowest enrichment is arranged in the inner zone of the core, and the full-ceramic micro-encapsulated fuel assemblies in the inner zone of the core are 73 groups, and the number of the burnable poison rods in the assemblies is 12.

[0030] Correspondingly, the application further discloses a 24-month primary cycle pressurized water reactor core of full-ceramic micro-encapsulated fuel assemblies, which is obtained by loading by the method.

[0031] Compared with the prior art, the application can ensure that the pressurized water reactor core composed of 177 fuel assemblies has a core power increased by 15% compared with the rod-shaped fuel, reaches 3500MW, and has a 24-month primary cycle service life, so that the safety and economy of the core are obviously improved.

[0032] Embodiment 1

[0033] The embodiment discloses a 24-month primary cycle pressurized water reactor core loading method of full-ceramic micro-encapsulated fuel assemblies, which can be used for a pressurized water reactor core with an output heat power of 3500MW, and the core is composed of 177 full-ceramic micro-encapsulated fuel assemblies. In order to make the length of the primary cycle core reach 24 months and avoid too high enrichment to cause too high cost of the fuel assemblies and reduce the economy of the core, the enrichment of the fuel assemblies in the core is controlled in the range of 8% to 10%. In order to control the reactivity of the core, some fuel assemblies are provided with a plurality of burnable poison rods, and the burnable poison in the burnable poison rods can introduce a large enough negative reactivity, and can also well match the reactivity of the burnup reduction, so as to realize the control of the reactivity of the core.

[0034] In the embodiment, the full-ceramic micro-encapsulated fuel assemblies are divided into three zones according to the enrichment, and the enrichment of the full-ceramic micro-encapsulated fuel assemblies in the three zones is controlled in the range of 8% to 10%, wherein:

[0035] 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, wherein the number of burnable poison rods in part of the assemblies is 8, and the number of burnable poison rods in another part of the assemblies is 12;

[0036] 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, and the number of burnable poison rods in the assemblies is 12.

[0037] 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, and the number of burnable poison rods in the assemblies is 12.

[0038] In some embodiments, the enrichment of the full-ceramic micro-encapsulated fuel assemblies in the three zones is 8%, 9% and 10% respectively, wherein:

[0039] The full-ceramic micro-encapsulated fuel assemblies with the highest enrichment of 10% are arranged in the outer zone of the core, and as shown in Table 1, the full-ceramic micro-encapsulated fuel assemblies with the highest enrichment of 10% are 72 groups, wherein the number of burnable poison rods in part of the assemblies is 8, and the number of burnable poison rods in another part of the assemblies is 12.

[0040] The above arrangement and number of full-ceramic micro-encapsulated fuel assemblies with 10% enrichment and the arrangement and number of burnable poisons are only one of the required schemes, and of course there are other schemes, which will not be repeated here.

[0041] The full-ceramic micro-encapsulated fuel assemblies with relatively low enrichment of 9% are arranged in the middle zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with relatively low enrichment of 9% are 32 groups, and the number of burnable poison rods in the assemblies is 12.

[0042] The above arrangement and number of full-ceramic micro-encapsulated fuel assemblies with 9% enrichment and the arrangement and number of burnable poisons are only one of the required schemes, and of course there are other schemes, which will not be repeated here.

[0043] The full-ceramic micro-encapsulated fuel assemblies with the lowest enrichment of 8% are arranged in the inner zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with the lowest enrichment of 8% are 73 groups, and the number of burnable poison rods in the assemblies is 12.

[0044] The above arrangement and number of full-ceramic micro-encapsulated fuel assemblies with 8% enrichment and the arrangement and number of burnable poisons are only one of the required schemes, and of course there are other schemes, which will not be repeated here.

[0045] Table 1

[0046]

[0047] Specifically, the height of the active core section is 365.76 cm, and the size of the ceramic micro-encapsulated fuel assembly is 12 feet. The ceramic micro-encapsulated fuel assembly comprises a plurality of fuel rods, guide tubes and instrument tubes. In this embodiment, the ceramic micro-encapsulated fuel assembly comprises 160 fuel rods, 8 guide tubes and 1 instrument tube. The fuel rods in each full ceramic micro-encapsulated fuel assembly are arranged in a 13x13 manner. The fuel rod comprises a plurality of fuel pellets formed by dispersing fuel particles in a SiC matrix, and the fuel particles are composed of a fuel kernel and a cladding layer.

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

[0049] In some embodiments, 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.

[0050] In some embodiments, the weight percentage of Er2O3 in the burnable poison rod is 12.0%, which is beneficial to control the core reactivity distribution flattening and the core safety, and the 12% content of the burnable poison is just right for the core, which does not cause too much poison penalty, nor does it cause the core power flattening effect to be poor and the Fdh to be out of limit.

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

[0052] The embodiment also discloses a 24-month primary cycle pressurized water reactor core of the full ceramic micro-encapsulated fuel assembly of the pressurized water reactor, which has the structure as described above.

[0053] Compared with the prior art, the loading method of the 24-month primary cycle pressurized water reactor core of the full ceramic micro-encapsulated fuel assembly can ensure that the pressurized water reactor core composed of 177 fuel assemblies has a core power increased by 15% compared with the conventional rod fuel (i.e., the UO2 pellets are in the form of a circular rod with a cladding), which can reach 3500 MW, and the primary cycle service life length reaches 24 months, and the core safety and economy are obviously improved.

[0054] And, the full ceramic microcapsule encapsulated fuel has better fission product containment capacity due to the design characteristics of the coating layer, has the significant advantages of high temperature resistance, corrosion resistance, and no hydrogen generation, can greatly reduce the possibility of large-scale release under severe accidents and the demand for off-site emergency, is beneficial to the simplification of nuclear power plant equipment systems, and plays a crucial role in the improvement of economy.

[0055] Embodiment 2

[0056] The embodiment discloses a 24-month primary cycle pressurized water reactor core loading method of a full ceramic microcapsule encapsulated fuel assembly, which is used for a pressurized water reactor core with an output thermal power of 3500 MW, and is basically same as the method in the embodiment 1, and the difference lies in that:

[0057] As shown in Figure 1 , arranged in order from right to left by A-R along the abscissa, and arranged in order from top to bottom by 1-15 along the ordinate, the method comprises

[0058] arranging 73 groups of full ceramic microcapsule encapsulated fuel assemblies with an enrichment degree of 8% and containing 12 burnable poison rods at positions of 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, J9, 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, H13 in the core;

[0059] arranging 32 groups of full ceramic microcapsule encapsulated fuel assemblies with an enrichment degree of 9% and containing 12 burnable poison rods at positions of 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, H14 in the core.

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

[0061] The 52 groups of full-ceramic micro-encapsulated fuel assemblies with 10% enrichment and 12 burnable poison rods are arranged in the positions 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, F15 of the reactor core.

[0062] It should be noted that, Figure 1 The position of the fuel assembly in the reactor core is represented by a combination of letters and numbers, for example, H3 indicates that the position of the fuel assembly in the reactor core is H3.

[0063] The embodiment also discloses a 24-month primary cycle pressurized water reactor core of full-ceramic micro-encapsulated fuel assemblies obtained by the method, and the specific structure is as described above.

[0064] According to calculation, the main parameters of the primary cycle of the pressurized water reactor core of the 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 / °C) -0.200 Assembly maximum burnup value (MWd / tU) 37946

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

[0068] Further, it can be determined that a 24-month primary cycle pressurized water reactor core loading method of full-ceramic micro-encapsulated fuel assemblies can be used to apply full-ceramic micro-encapsulated fuel assemblies to 177 assemblies of a pressurized water reactor core without changing the size of the reactor core, the power of the reactor core is increased by 15% compared with the use of rod-shaped fuel, and the primary cycle service life length reaches 24 months.

[0069] It can be understood that the above embodiments are only exemplary embodiments for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. A method for loading a pressurized water reactor core with fuel assemblies encapsulated with all-ceramic microcapsules for a first cycle of 24 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 assembly is loaded in three zones according to the enrichment degree, and the enrichment degree of the full-ceramic micro-encapsulated fuel assemblies in the three zones is controlled in the range of 8% to 10%, wherein: The full-ceramic micro-encapsulated fuel assemblies with the highest enrichment degree are placed in the outer zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with the highest enrichment degree are 72 groups, wherein the number of burnable poison rods in part of the assemblies is 8, and the number of burnable poison rods in another part of the assemblies is 12; The full-ceramic micro-encapsulated fuel assemblies with relatively low enrichment degree are arranged in the middle zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with relatively low enrichment degree are 32 groups, and the number of burnable poison rods in the assemblies is 12; The full-ceramic micro-encapsulated fuel assemblies with the lowest enrichment degree are arranged in the inner zone of the core, and the full-ceramic micro-encapsulated fuel assemblies with the lowest enrichment degree are 73 groups, and the number of burnable poison rods in the assemblies is 12.

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 24 months according to claim 1, characterized in that, The enrichment degrees of the full-ceramic micro-encapsulated fuel assemblies in the three zones are 8%, 9% and 10% respectively, wherein: The full-ceramic micro-encapsulated fuel assemblies with an enrichment degree of 10% are placed in the outer zone of the core; The full-ceramic micro-encapsulated fuel assemblies with an enrichment degree of 9% are arranged in the middle zone of the core; The full-ceramic micro-encapsulated fuel assemblies with an enrichment degree of 8% are arranged in the inner zone of the core.

3. The core loading method of a first cycle 24-month pressurized water reactor using full-ceramic micro-encapsulated fuel assemblies according to claim 1 or 2, characterized in that, The number of full-ceramic micro-encapsulated fuel assemblies with an enrichment degree of 10% containing 8 burnable poison rods is 20 groups; The number of full-ceramic micro-encapsulated fuel assemblies with an enrichment degree of 10% containing 12 burnable poison rods is 52 groups.

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 24 months according to claim 3, characterized in that, 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.

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 24 months according to claim 3, characterized in that, The weight percentage of Er2O3 in the burnable poison rod is 12.0%.

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

7. A full ceramic microencapsulated fuel assembly first cycle 24 month pressurized water reactor core, characterized in that, It is loaded by the method of any one of claims 1-6.

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