Uranium-plutonium mixed fuel for pressurized water reactor and method for configuring the same

Abstract

The application discloses a configuration method of uranium-plutonium mixed fuel for a pressurized water reactor, comprising the following steps: S1, calculating the equivalent share difference D of a target raw material; S2, calculating the equivalent life coefficient C of an existing raw material; S3, determining the uranium-plutonium mixed ratio of the existing raw material; and S4, taking the existing raw material and uranium raw material, mixing and configuring to obtain the uranium-plutonium mixed fuel for the pressurized water reactor according to the uranium-plutonium mixed ratio of the existing raw material. The application further discloses the uranium-plutonium mixed fuel for the pressurized water reactor configured by using the configuration method. The application can utilize the existing raw material in a spent fuel reprocessing plant, configure the MOX fuel with the same core life length compared with the MOX fuel configured by the target raw material without changing the plutonium isotope composition, break the limitation of raw material selection in the prior art, and fully utilize the existing raw material in the spent fuel reprocessing plant.

Description

Technical Field

[0001] This invention belongs to the field of nuclear industry technology, specifically relating to a uranium-plutonium mixed fuel for pressurized water reactors and its preparation method. Background Technology

[0002] The use of mixed uranium-plutonium fuel (MOX fuel) in pressurized water reactors is an important component of the closed nuclear fuel cycle and a requirement for third-generation pressurized water reactors. Changes in parameters such as the Pu isotope composition and PuO2 content in MOX fuel can alter its reactivity, inevitably affecting parameters such as core lifespan. Among core characteristics, the impact on core lifespan is the most significant.

[0003] Based on current experience in procuring UO2 fuel for pressurized water reactors, nuclear power plants determine the type and quantity of new fuel assemblies to be used in subsequent refueling cycles through fuel management reports, thereby procuring the corresponding fuel assemblies from fuel manufacturers in advance. Similarly, for MOX fuel, nuclear power plants need to provide relevant parameters to MOX fuel manufacturers, including the PuO2 content, Pu isotopic composition, and number of assemblies. In other words, currently, for MOX, nuclear power plants need to provide MOX fuel manufacturers with relevant parameters such as PuO2 content, Pu isotopic composition, and number of assemblies. The manufacturing process requires strict adherence to the provided parameters when selecting raw materials (target raw materials), and existing raw materials in spent fuel reprocessing plants cannot be used directly, severely limiting raw material selection. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a uranium-plutonium mixed fuel for pressurized water reactors and a method for its preparation. This preparation method can utilize existing raw materials in spent fuel reprocessing plants to prepare MOX fuel with the same core lifespan as MOX fuel prepared using target raw materials without changing the plutonium isotope composition. This breaks the limitations on raw material selection in the prior art and makes full use of existing raw materials in spent fuel reprocessing plants.

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

[0006] According to one aspect of the present invention, a method for preparing a uranium-plutonium mixed fuel for a pressurized water reactor is provided, comprising:

[0007] S1, calculate the equivalent share difference D of the target raw material;

[0008] S2, calculate the equivalent lifespan coefficient C of the existing raw materials;

[0009] S3. Determine the uranium-plutonium mixing ratio of the existing raw materials based on the equivalent share difference D of the target raw materials and the equivalent lifetime coefficient C of the existing raw materials.

[0010] S4. Based on the existing uranium-plutonium mixing ratio of raw materials, take existing raw materials and uranium raw materials, mix them, and prepare uranium-plutonium mixed fuel for pressurized water reactors.

[0011] Preferably, the calculation of the equivalent share difference D of the target raw material includes the following steps:

[0012] S101, determine the composition of plutonium isotopes in the target raw material;

[0013] S102, Based on the plutonium isotope composition of the target raw material, calculate the target components respectively. 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 ;

[0014] S103, based on the target component 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 The equivalent share difference D is calculated.

[0015] Preferably, the target components are calculated based on the plutonium isotope composition of the target raw materials. 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 This includes the following steps:

[0016] S1021, defines the target raw material in 238 Pu、 239 Pu、 240 Pu、 241 Pu、 242 The mass fraction of Pu is P 238 p 239 P 240 P 241 P 242 ;

[0017] S1022, according to the target component 239 The formula for calculating the equivalent mass share of Pu is m. 239 =p 239 +2.59×p 241 m was calculated 239 The value, based on the target component 240 The formula for calculating the equivalent mass share of Pu is m. 240 =2.52×P 238 +P 240 +1.68×P 242m was calculated 240 The value of .

[0018] Preferably, the formula for calculating the equivalent share difference D is D = m 239 -m 240 .

[0019] Preferably, the calculation of the equivalent lifespan coefficient C of the existing raw materials includes the following steps:

[0020] S201, determine the plutonium isotope composition of existing raw materials;

[0021] S202, based on the plutonium isotope composition of the existing raw materials, calculate the composition respectively. 239 Pu's equivalent mass share M 239 and ingredients 240 Pu's equivalent mass share M 240 ;

[0022] S203, based on the composition of existing raw materials 239 Pu's equivalent mass share M 239 and ingredients 240 Pu's equivalent mass share M 240 The equivalent life coefficient C is calculated.

[0023] Preferably, the composition is calculated based on the plutonium isotope composition of the existing raw materials. 239 Pu's equivalent mass share M 239 and ingredients 240 Pu's equivalent mass share M 240 This includes the following steps:

[0024] S2021 defines the existing raw materials in 238 Pu、 239 Pu、 240 Pu、 241 Pu、 242 The mass fraction of Pu is P 238 P 239 P 240 P 241 P 242 ;

[0025] S2022, according to ingredients 239 The formula for calculating the equivalent mass share of Pu is M. 239 =P 239 +2.59×P 241 Calculate M 239 The value depends on the ingredients. 240 The formula for calculating the equivalent mass share of Pu is M. 240 =2.52×P 238 +P240 +1.68×P 242 Calculate M 240 The value of .

[0026] Preferably, the formula for calculating the equivalent lifespan coefficient C is as follows:

[0027] Preferably, determining the uranium-plutonium mixing ratio of the existing raw materials based on the equivalent proportion difference D of the target raw materials and the equivalent lifetime coefficient C of the existing raw materials includes the following steps:

[0028] S301, define the proportion of plutonium mass in the target raw material to the total mass of uranium and plutonium as the target quality t of plutonium, and determine the target quality t of plutonium in the target raw material based on the plutonium isotope composition of the target raw material.

[0029] S302, define the proportion of plutonium mass in MOX fuel to the total mass of uranium and plutonium as the current quality T of plutonium, and calculate the current quality T of plutonium based on the target quality t of plutonium in the target raw material and the equivalent lifetime coefficient C of the existing raw material.

[0030] S303, based on the existing quality T of plutonium, determine the required proportion of existing raw materials and uranium raw materials in MOX fuel. The required proportion of existing raw materials and uranium raw materials is the uranium-plutonium mixing ratio of existing raw materials.

[0031] Preferably, the existing quality T of the plutonium is calculated using the formula T = C × t.

[0032] According to another aspect of the present invention, a uranium-plutonium mixed fuel for pressurized water reactors is provided, which is configured using the method described above.

[0033] Beneficial effects:

[0034] The present invention relates to a uranium-plutonium mixed fuel for pressurized water reactors and its preparation method, which solves for the equivalent mass fraction of Pu isotopes and utilizes the target raw material's... 239 Pu equivalent quality share and 240 The Pu equivalent mass fraction yields the plutonium mass fraction required to configure existing feedstocks for a core lifespan equivalent to that of the target feedstock. By blending and proportioning MOX fuel according to this plutonium mass fraction, existing feedstocks obtained through processes such as spent fuel reprocessing plants can be used to formulate MOX fuel products with the same core lifespan as those formulated with the target feedstock, without altering the plutonium isotope composition. Compared to existing technologies, this invention overcomes the limitations on feedstock selection, is not restricted by the plutonium composition of existing feedstocks, and does not require altering the plutonium isotope composition of existing feedstocks. It can fully utilize existing feedstocks in spent fuel reprocessing plants and make the most of all feedstocks in the treasury. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the method for preparing uranium-plutonium mixed fuel for a pressurized water reactor according to an embodiment of the present invention. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] 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.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] In response to the problems of existing pressurized water reactor (PWR) uranium-plutonium mixed fuel (MOX fuel) where the nuclear power plant provides MOX fuel manufacturing plants with parameters such as PuO2 content, Pu isotopic composition, and assembly quantity, the manufacturing process requires strict adherence to these parameters for selecting target raw materials, making it impossible to directly use existing raw materials from spent fuel reprocessing plants, thus severely limiting raw material selection, the applicant believes that when the plutonium isotopic composition of MOX fuel assemblies changes, if plutonium isotope mixing is not possible, the characteristics of maintaining a core lifespan as consistent as possible with the original design can be achieved by adjusting the uranium-plutonium mass ratio. Therefore, this invention provides a method for configuring uranium-plutonium mixed fuel for pressurized water reactors, comprising:

[0041] Step S1: Calculate the equivalent share difference D of the target raw material;

[0042] Step S2: Calculate the equivalent lifespan coefficient C of the existing raw materials;

[0043] Step S3: Determine the uranium-plutonium mixing ratio of the existing raw materials based on the equivalent share difference D of the target raw materials and the equivalent lifetime coefficient C of the existing raw materials.

[0044] Step S4: Based on the existing uranium-plutonium mixing ratio of the raw materials, take the existing raw materials and uranium raw materials, mix them, and prepare uranium-plutonium mixed fuel for pressurized water reactors.

[0045] Accordingly, the present invention provides a uranium-plutonium mixed fuel for pressurized water reactors, which is prepared using the above-described configuration method.

[0046] Example 1

[0047] like Figure 1 As shown in the figure, this embodiment discloses a method for preparing a uranium-plutonium mixed fuel for a pressurized water reactor, including:

[0048] Step S1: Calculate the equivalent share difference D of the target raw material;

[0049] Step S2: Calculate the equivalent lifespan coefficient C of the existing raw materials;

[0050] Step S3: Determine the uranium-plutonium mixing ratio of the existing raw materials based on the equivalent share difference D of the target raw materials and the equivalent lifetime coefficient C of the existing raw materials.

[0051] Step S4: Based on the existing uranium-plutonium mixing ratio of the raw materials, take the existing raw materials and uranium raw materials, mix them, and prepare uranium-plutonium mixed fuel for pressurized water reactors.

[0052] In some implementations, step S1, calculating the equivalent share difference D of the target raw material, includes the following steps:

[0053] S101, determine the composition of a set of plutonium isotopes as the target raw material;

[0054] S102, Calculate the target composition based on the plutonium isotope composition of the target raw material. 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 ;

[0055] S103, based on the target component 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 The equivalent share difference D is calculated.

[0056] In some more specific embodiments, step S101 involves determining a set of plutonium isotope compositions as the target raw material. Specifically, the target lifespan of the reactor core can be determined based on the requirements for the core lifespan, and raw materials with the target lifespan can be selected as the target raw material. For example, the plutonium isotope composition corresponding to the statistical average unloading burnup and a certain cooling time corresponding to a certain initial enrichment can be used as the target raw material.

[0057] In this embodiment, the statistical average unloading fuel consumption corresponding to a typical initial enrichment degree and the plutonium isotope composition corresponding to a certain cooling time are selected as the plutonium isotope composition of the target raw material.

[0058] In some more specific embodiments, step S102 involves calculating the target components based on the plutonium isotope composition of the target raw material. 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 Specifically, it includes the following steps:

[0059] S1021, defines the target raw material in 238 Pu、 239 Pu、 240 Pu、 241 Pu、 242 The mass fraction of Pu is P 238 P 239 P 240 P 241 P 242 ;

[0060] S1022, according to the target component 239 P u The formula for calculating the equivalent quality share m 239 =p 239 +2.59×p 241 m was calculated 239The value, based on the target component 240 The formula for calculating the equivalent mass share of Pu is m. 240 =2.52×P 238 +p 240 +1.68×p 242 m was calculated 240 The value of .

[0061] In some more specific implementations, the target component is defined. 239 P u Equivalent quality share and target component 240 P u The difference in equivalent quality shares is called the equivalent share difference D, and the formula for calculating the equivalent share difference D is D = m 239 -m 240 .

[0062] In some implementations, step S2, calculating the equivalent lifespan factor C of the existing raw materials, includes the following steps:

[0063] S201, determine the plutonium isotope composition of existing raw materials. Specifically, it is generally determined based on the actual situation of the user. For example, it can be determined based on the PuO2 raw materials stored in the spent fuel reprocessing plant.

[0064] S202, based on the plutonium isotope composition of the existing raw materials, calculate the existing components respectively. 239 Pu's equivalent mass share M 239 and existing raw material components 240 Pu's equivalent mass share M 240 ;

[0065] S203, based on existing raw material composition 239 Pu's equivalent mass share M 239 and existing raw material components 240 Pu's equivalent mass share M 240 The equivalent life coefficient C is calculated.

[0066] In some more specific embodiments, step S102 involves calculating the composition of the existing raw materials based on the plutonium isotope composition of the existing raw materials. 239 Pu's equivalent mass share M 239 and existing raw material components 240 Pu's equivalent mass share M 240 This includes the following steps:

[0067] S2021 defines the existing raw materials in 238 Pu、 239 Pu、 240 Pu、 241 Pu、 242The mass fraction of Pu is P 238 P 239 P 240 P 241 P 242 ;

[0068] S2022, based on existing raw material composition 239 The formula for calculating the equivalent mass share of Pu is M. 239 =P 239 +2.59×P 241 Calculate M 239 The value is based on the existing raw material composition. 240 The formula for calculating the equivalent mass share of Pu is M. 240 =2.52×P 238 +P 240 +1.68×P 242 Calculate M 240 The value of .

[0069] In some more specific implementations, the existing raw material composition is defined. 240 The equivalent mass fraction of Pu, after taking into account the equivalent fraction difference D, is compared with the existing raw material composition. 239 The equivalent mass share of Pu is the equivalent lifespan factor C, and the formula for calculating the equivalent lifespan factor C is:

[0070]

[0071] In some implementations, step S3, determining the uranium-plutonium mixing ratio of the existing raw materials based on the equivalent share difference D of the target raw materials and the equivalent lifetime coefficient C of the existing raw materials, includes the following steps:

[0072] S301, define the proportion of plutonium mass in the target raw material to the total mass of uranium and plutonium as the target quality t of plutonium, and determine the target quality t of plutonium in the target raw material based on the plutonium isotope composition of the target raw material.

[0073] S302, the proportion of plutonium mass in the pressurized water reactor mixed uranium-plutonium fuel (MOX fuel) to be configured in this embodiment is defined as the existing quality T of plutonium. Based on the target quality t of plutonium in the target raw material and the equivalent lifetime coefficient C of the existing raw material, the existing quality T of plutonium in MOX fuel is calculated. The formula for calculating the existing quality T of plutonium is T = C × t.

[0074] S303. Based on the existing quality T of plutonium, while keeping the plutonium isotope composition of the existing raw materials unchanged, determine the required ratio of existing raw materials and uranium raw materials in MOX fuel. The required ratio of existing raw materials and uranium raw materials is the uranium-plutonium mixing ratio of the existing raw materials.

[0075] The method for configuring uranium-plutonium mixed fuel for pressurized water reactors in this embodiment solves for the equivalent mass fraction of Pu isotopes, utilizing the target raw materials'... 239 Pu equivalent quality share and 240 The Pu equivalent mass fraction method yields the plutonium mass fraction required to configure existing feedstocks for a core lifespan equivalent to that of the target feedstock. MOX fuel is then blended and proportioned according to this plutonium mass fraction. This method utilizes existing feedstocks obtained from processes such as spent fuel reprocessing plants, and without altering the plutonium isotope composition, can formulate MOX fuel products with the same core lifespan as those formulated with the target feedstock. Compared to existing technologies, this formulation method overcomes the limitations imposed by existing feedstock selection, is not restricted by the plutonium composition of existing feedstocks, and does not require altering the plutonium isotope composition of existing feedstocks. It can fully utilize existing feedstocks in spent fuel reprocessing plants and make the most of all feedstocks in the treasury.

[0076] Example 2

[0077] like Figure 1 As shown, this embodiment discloses a method for preparing a uranium-plutonium mixed fuel for a pressurized water reactor, including steps S1 to S4:

[0078] Step S1, calculate the equivalent share difference D of the target raw material, specifically including the following steps S101 to S103:

[0079] S101, determine the composition of plutonium isotopes used as the target raw material.

[0080] Taking the average unloading burnup of spent fuel assemblies with a certain initial enrichment level in domestic pressurized water reactors as an example, and the isotopic composition of plutonium after 20 years of cooling, UO2 (i.e., uranium raw material) uses depleted uranium as the target raw material, and the plutonium isotopic composition (mass fraction) is shown in Table 1.

[0081] Table 1. Plutonium isotope composition (%) of the target raw material

[0082] Cooldown time <![CDATA[ 238 Pu]]> <![CDATA[ 239 Pu]]> <![CDATA[ 240 Pu]]> <![CDATA[ 241 Pu]]> <![CDATA[ 242 Pu]]> Cooling for 20 years 2.27 60.94 24.39 6.11 6.30

[0083] S102, Calculate the target composition based on the plutonium isotope composition of the target raw material. 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 .

[0084] Specifically, based on the target component 239 The formula for calculating the equivalent mass share of Pu is m. 239 =p 239 +2.59×p 241 The target component was calculated. 239Pu equivalent mass share m 239 =76.75.

[0085] According to the target ingredients 240 The formula for calculating the equivalent mass share of Pu is m. 240 =2.52×p 238 +p 240 +1.68×p 242 Calculated 240 Pu equivalent mass share m 240 =40.69.

[0086] S103, based on the target component 239 Pu's equivalent mass share m 239 and target components 240 Pu's equivalent mass share m 240 The equivalent share difference D is calculated.

[0087] Specifically, according to the formula for calculating the equivalent share difference D, D = m 239 -m 240 The equivalent share difference D was calculated to be 36.07.

[0088] Step S2, calculate the equivalent lifespan coefficient C of the existing raw materials, specifically including the following steps S201 to S203:

[0089] S201, determine the plutonium isotope composition of existing raw materials.

[0090] In this embodiment, it is assumed that there are three existing raw materials, and the plutonium isotope composition (mass fraction) of these three existing raw materials is shown in Table 2.

[0091] Table 2. Plutonium isotope composition (%) of existing raw materials

[0092] Element <![CDATA[ 238 Pu]]> <![CDATA[ 239 Pu]]> <![CDATA[ 240 Pu]]> <![CDATA[ 241 Pu]]> <![CDATA[ 242 Pu]]> Existing raw material 1 0.68 75.62 17.70 4.19 1.81 Existing raw materials 2 3.70 55.37 25.71 6.39 8.82 Existing raw materials 3 0.18 77.63 18.13 2.95 1.11

[0093] S202, based on the plutonium isotope composition of the existing raw materials, calculate the composition respectively. 239 Pu's equivalent mass share M 239 and ingredients 240 Pu's equivalent mass share M 240 .

[0094] Specifically, based on the composition of existing raw materials 239 The formula for calculating the equivalent mass share of Pu is M. 239 =P 239 +2.59×P 241 The M values ​​of existing raw material 1, existing raw material 2, and existing raw material 3 are calculated. 239 The values ​​are calculated, and the results are shown in Table 3.

[0095] Table 3 Composition of existing raw materials 239 Pu's equivalent mass share

[0096] Element <![CDATA[M 239 ]]> Existing raw material 1 86.47 Existing raw materials 2 71.94 Existing raw materials 3 85.28

[0097] Based on the composition of existing raw materials 240 The formula for calculating the equivalent mass share of Pu is M. 240 =2.52×P 238 +P 240 +1.68×P 242 The M values ​​for existing raw material 1, existing raw material 2, and existing raw material 3 are calculated respectively. 240 The values ​​are calculated, and the results are shown in Table 4:

[0098] Table 4 Composition of Existing Raw Materials 240 Pu's equivalent mass share

[0099] Element <![CDATA[M 240 ]]> Existing raw material 1 22.45 Existing raw materials 2 49.85 Existing raw materials 3 20.44

[0100] S203, based on the composition of existing raw materials 239 Pu's equivalent mass share M 239 and ingredients 240 Pu's equivalent mass share M 240 The equivalent life coefficient C was calculated.

[0101] Specifically, the formula for calculating the equivalent lifespan factor C is as follows: The equivalent life coefficients C of existing raw material 1, existing raw material 2, and existing raw material 3 were calculated respectively, and the calculation results are shown in Table 5.

[0102] Table 5 Equivalent life coefficient C of existing raw materials

[0103] Element C Existing raw material 1 0.68 Existing raw materials 2 1.19 Existing raw materials 3 0.66

[0104] Step S3, determining the uranium-plutonium mixing ratio of the existing raw materials, specifically includes the following steps S301 to S303:

[0105] S301, define the proportion of plutonium mass in the target raw material to the total mass of uranium and plutonium as the target quality t of plutonium, and calculate and determine the target quality t of plutonium in the target raw material based on the plutonium isotope composition of the target raw material.

[0106] Specifically, assuming that there are three types of MOX fuel assemblies used in the reactor core, namely MOX assembly 1, MOX assembly 2 and MOX assembly 3, the plutonium content of each MOX assembly is arranged in three zones (zone 1, zone 2 and zone 3). According to the definition of the target quality t of plutonium in the target raw material, the target quality t of plutonium in the MOX assembly of each zone is determined as shown in Table 6.

[0107] Table 6 Target quality t (%) of plutonium

[0108] Target quality (%) of plutonium in each region MOX Component 1 MOX Component 2 MOX Component 3 Zone 1 4 4.85 5 Zone 2 5 6.95 7 Zone 3 9 9.52 10

[0109] S302 defines the proportion of plutonium mass in MOX fuel to the total mass of uranium and plutonium as the current quality T of plutonium, and calculates the current quality T of plutonium based on the target quality t of plutonium in the target feedstock and the equivalent lifetime coefficient C of the existing feedstock.

[0110] Specifically, based on the formula for calculating the existing quality T of plutonium as T=C×t, the requirements for the existing quality T of plutonium when using MOX fuel prepared with existing raw material 1, existing raw material 2, and existing raw material 3 are shown in Table 7.

[0111] Table 7. Current quality T (%) of plutonium

[0112]

[0113] S303. Based on the existing quality T of plutonium (Table 7), while keeping the plutonium isotope composition of the existing raw materials unchanged, determine the required ratio of existing raw materials and uranium raw materials in MOX fuel. The required ratio of existing raw materials and uranium raw materials is the uranium-plutonium mixing ratio of the existing raw materials.

[0114] Step S4: Based on the existing uranium-plutonium mixing ratio of the raw materials, take the existing raw materials and uranium raw materials, mix them, and you can prepare uranium-plutonium mixed fuel for pressurized water reactors.

[0115] Using the above method, a uranium-plutonium mixed fuel (MOX fuel) assembly for pressurized water reactors was prepared based on existing raw materials 1, 2, and 3. While keeping the core loading scheme and operating parameters unchanged, the assembly-core calculation program was used for calculation, and the results were compared with those when using the target raw materials. The comparison results are shown in Table 8.

[0116] Table 8 Core Lifetime (days)

[0117] raw material Lifespan (days) Difference in proportion to target raw materials Target raw materials 487 0.00％ Existing raw material 1 487 0.00％ Existing raw materials 2 484 -0.62％ Existing raw materials 3 486 -0.21％

[0118] As shown in Table 8, under the condition that the core loading scheme and operating parameters remain unchanged, the MOX assemblies prepared by mixing different existing raw materials using the method of this embodiment have a core lifespan that is in good agreement with the core lifespan when using the target raw materials. The difference in core lifespan ratio is less than 1%, which is acceptable. In other words, the uranium-plutonium mixed fuel (MOX fuel) for pressurized water reactors prepared by the method of this embodiment has the same core lifespan as the MOX fuel prepared using the target raw materials.

[0119] Example 3

[0120] This embodiment discloses a uranium-plutonium mixed fuel for pressurized water reactors, which is configured using the method described in Embodiment 1 or 2.

[0121] 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 configuring uranium-plutonium mixed fuel for a pressurized water reactor, comprising: S1, calculating the equivalent share difference D of the target raw material, the equivalent share difference D being the difference between the target component 239 the equivalent mass share m of Pu 239 and the target component 240 the equivalent mass share m of Pu 240 D = m 239 -m 240 ; S2, calculating the equivalent life coefficient C of the existing raw material, which is the ratio of the existing raw material composition 240 The equivalent mass share M of Pu 239 After considering the equivalent share difference D, the ratio of the existing raw material composition 239 The equivalent mass share M of Pu 240 The calculation formula is: S3, determining a uranium-plutonium mixing ratio of the existing raw material according to an equivalent share difference D of the target raw material and an equivalent lifetime coefficient C of the existing raw material; S4, mixing the existing raw material and uranium raw material according to the uranium-plutonium mixing ratio of the existing raw material to obtain the uranium-plutonium mixed fuel for the pressurized water reactor.

2. The method of configuring a uranium-plutonium mixed fuel for a pressurized water reactor according to claim 1, characterized by, The calculation of the equivalent share difference D of the target raw material comprises the following steps: S101, determining a composition of plutonium isotopes in the target raw material; S102, the target component is calculated according to the composition of plutonium isotopes in the target raw material 239 Equivalent mass fraction m of Pu 239 and the target component 240 Equivalent mass fraction m of Pu 240 ; S103, calculating the equivalent mass fraction m of Pu according to the target composition 239 Pu's equivalent mass fraction m 239 and the target composition 240 Pu's equivalent mass fraction m 240 , and the equivalent fraction difference D is calculated.

3. The method of arranging a uranium-plutonium mixed fuel for a pressurized water reactor according to claim 2, characterized by, said target component is calculated from the composition of the plutonium isotopes in the target feed material 239 the equivalent mass fraction m of Pu 239 and the target component 240 the equivalent mass fraction m of Pu 240 comprising the steps of: S1021, define the target raw material in 238 Pu, 239 Pu, 240 Pu, 241 Pu, 242 Pu's mass share is p 238 , p 239 , p 240 , p 241 , p 242 ; S1022, according to the target component 239 The formula for calculating the equivalent mass share of Pu is m. 239 =p 239 +2.59×p 241 m was calculated 239 The value, based on the target component 240 The formula for calculating the equivalent mass share of Pu is m. 240 =2.52×p 238 +p 240 +1.68×p 242 m was calculated 240 The value of .

4. The method of arranging a mixed uranium-plutonium fuel for a pressurized water reactor according to claim 1, characterized by, The calculation of the equivalent lifetime coefficient C of the existing raw material comprises the following steps: S201, determining a composition of plutonium isotopes of the existing raw material; S202, according to the composition of the existing raw material plutonium isotope, respectively, to calculate the composition 239 Equivalent mass fraction M of Pu 239 and the composition 240 Equivalent mass fraction M of Pu 240 ; S203, the equivalent mass fraction M of Pu is calculated according to the components in the existing raw material 239 The equivalent mass fraction M of Pu 239 and components 240 The equivalent mass fraction M of Pu 240 , and the equivalent service life coefficient C is calculated.

5. The method of arranging a uranium-plutonium mixed fuel for a pressurized water reactor according to claim 4, characterized by, said composition of plutonium isotopes in the existing feed material is calculated separately 239 the equivalent mass fraction M of Pu 239 and the composition 240 the equivalent mass fraction M of Pu 240 comprising the following steps: S2021, define the mass fraction of Pu in the existing raw material 238 Pu, 239 Pu, 240 Pu, 241 Pu, 242 The mass fraction of Pu is P 238 , P 239 , P 240 , P 241 , P 242 ; S2022, according to the composition 239 Pu equivalent mass share calculation formula M 239 = P 239 + 2.59 x P 241 The value of M 239 is calculated, according to the composition 240 Pu equivalent mass share calculation formula M 240 = 2.52 x P 238 + P 240 + 1.68 x P 242 The value of M 240 is calculated.

6. The method of configuring a mixed uranium-plutonium fuel for a pressurized water reactor according to claim 1, characterized by, The determination of the uranium-plutonium mixing ratio of the existing raw material according to the equivalent share difference D of the target raw material and the equivalent lifetime coefficient C of the existing raw material comprises the following steps: S301, defining a target quality t of plutonium in the target raw material as a share of plutonium in total uranium-plutonium mass, and determining the target quality t of plutonium in the target raw material according to the composition of plutonium isotopes of the target raw material; S302, defining an existing quality T of plutonium in the MOX fuel as a share of plutonium in total uranium-plutonium mass, and calculating the existing quality T of plutonium according to the target quality t of plutonium in the target raw material and the equivalent lifetime coefficient C of the existing raw material; S303, determining a required usage ratio of the existing raw material and uranium raw material in the MOX fuel according to the existing quality T of plutonium, the required usage ratio of the existing raw material and uranium raw material being the uranium-plutonium mixing ratio of the existing raw material.

7. The method of arranging a uranium-plutonium mixed fuel for a pressurized water reactor according to claim 6, characterized by, The calculation formula of the existing quality T of plutonium is T=Cxt.

8. A uranium-plutonium mixed fuel for a pressurized water reactor, characterized by, The uranium-plutonium mixed fuel is configured by the method of any one of claims 1-7.

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