Neutron field construction method for research reactor

Abstract

The invention relates to the technical field of reactor engineering design, in particular to a neutron field construction method for a research reactor, and the method comprises the following steps: obtaining irradiation test indexes; determining neutron field characteristics corresponding to the irradiation test indexes, wherein the neutron field characteristics comprise a neutron energy spectrum and a neutron fluence rate; on the basis of an inherent structure of an original research reactor body, an adjustment strategy of a structural member around an irradiation duct is determined based on neutron field characteristics; and constructing the neutron field based on the adjustment strategy. According to the invention, the movable reactor core components are flexibly arranged, and the loading capacity, the operating power and the control rod lifting strategy of the reactor core fuel element of the research reactor are adjusted, so that a specific neutron field required by the irradiation test can be constructed, a suitable irradiation environment is provided for various irradiation tests, and a beneficial reference is also provided for comprehensive and efficient utilization of the subsequent research reactor.

Description

Technical Field

[0001] This invention relates to the field of reactor engineering design technology, and more specifically, to a method for constructing a neutron field for a research reactor. Background Technology

[0002] One of the main uses of research reactors is irradiation testing of reactor fuel and materials. Currently, my country has a relatively small number of research reactors and scarce irradiation resources. In-service research reactors need to undertake a number of irradiation testing and isotope production tasks simultaneously. However, the irradiation test requirements vary depending on the application scenario of each irradiation task, which brings many difficulties to research reactors in meeting the requirements of various irradiation test indicators at the same time.

[0003] my country has conducted multiple batches of fuel and material irradiation tests using research reactors. However, no clear research results or relevant methods have been given on how to construct the neutron field required for fuel and material irradiation tests within the research reactor, while ensuring that it matches the inherent structure or operation mode of the research reactor.

[0004] Therefore, how to construct the neutron field environment required for fuel and materials without changing the inherent structure of the research reactor itself, and meet the requirements of various irradiation mission indicators, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for constructing a neutron field for a research reactor, in order to solve the technical problem of how to construct the neutron field environment required for fuel and materials without changing the inherent structure of the research reactor itself, and to meet the requirements of various irradiation mission indicators.

[0006] This invention is achieved through the following technical solution: a method for constructing a neutron field for research reactors, comprising the following steps: Obtain irradiation test parameters; Determine the neutron field characteristics corresponding to the irradiation test indicators, including the neutron energy spectrum and neutron flux rate; Based on the inherent structure of the original research reactor body, the adjustment strategy of the structural components around the irradiation channel is determined based on the neutron field characteristics. A neutron field is constructed based on the aforementioned adjustment strategy.

[0007] According to a preferred embodiment, the adjustment strategy includes adjusting one or more combinations of the arrangement position, component type, or arrangement quantity of components within the irradiation channel stack.

[0008] According to a preferred embodiment, the adjustment target of the irradiated channel reactor internals is one or more combinations of fuel elements, isotope targets, beryllium assemblies, aluminum assemblies, or stainless steel assemblies.

[0009] According to a preferred embodiment, the adjustment strategy includes adjusting the burn-out depth and / or the number of arrangement of irradiation channel fuel elements.

[0010] According to a preferred embodiment, the fuel element's burn depth adjustment range is 0 to 50%.

[0011] According to a preferred embodiment, the number of fuel elements arranged is adjustable from 25 to 80.

[0012] According to a preferred embodiment, the adjustment strategy includes adjusting the operating power of the research reactor.

[0013] According to a preferred embodiment, the operating power is adjusted from 0 to 80 MW.

[0014] According to a preferred embodiment, the adjustment strategy includes adjusting the lifting sequence of control rods within the research stack.

[0015] According to a preferred embodiment, the target for adjusting the lifting sequence of control rods within the research stack is the compensation rod.

[0016] The technical solution of the neutron field construction method for research reactors provided by the present invention has at least the following advantages and beneficial effects: By flexibly arranging movable core components and adjusting the fuel element loading, operating power and control rod lifting strategy of the research reactor core, the present invention can construct a specific neutron field required for irradiation tests, provide a suitable irradiation environment for various irradiation tests, and also provide a useful reference for the comprehensive and efficient utilization of research reactors in the future. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall process of the neutron field construction method provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the 80 fuel element boxes loaded into the reactor core according to Embodiment 1 of the present invention; Figure 3 This is a schematic diagram showing the types and quantities of in-pile components that can be arranged in a partial irradiation channel according to Embodiment 1 of the present invention. Figure 4 This is a schematic diagram of the fuel element burnup in a partially arranged irradiation channel according to Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of a reactor core loaded with 60 fuel element boxes as provided in Embodiment 1 of the present invention; Reference numerals: 100-fuel assembly, 200-isotope target, 300-beryllium assembly, 400-aluminum assembly, 500-stainless steel assembly, 600-irradiation channel, 700-control rod. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments 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, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Example 1 This invention provides a method for constructing a neutron field in a research reactor. Figure 1 For a schematic diagram of the overall process of this neutron field construction method, see [link / reference]. Figure 1 As shown, the neutron field construction method includes the following steps: Step S1: Obtain irradiation test parameters; Obtaining irradiation test parameters is a prerequisite for neutron field construction. In this embodiment, the irradiation test parameters refer to quantitative parameters determined according to the specific requirements of the irradiation mission, including but not limited to: the type of irradiated sample, the irradiation time period, the environmental conditions of the irradiation process, the specific position requirements of the sample in the irradiation channel, the expected damage level or activation degree of the sample after irradiation, etc., which will not be elaborated on here.

[0020] Step S2: Determine the neutron field characteristics corresponding to the irradiation test indicators; The core of this step is to transform the irradiation test indicators obtained in step S1 into neutron field physics target parameters that can be used to guide core physics calculations; in this embodiment, the neutron field characteristics are selected as neutron energy spectrum and neutron flux rate.

[0021] Regarding the quantification of the neutron energy spectrum, this embodiment transforms the indicators into specific energy spectrum distribution targets based on the neutron type requirements of the irradiation experiment. For example, if the experiment requires a high proportion of thermal neutrons, the target can be quantified as the thermal neutron distribution at a specific irradiation channel location. The proportion of fluence rate to total neutron fluence should not be less than a certain value; however, if the experiment requires research on material irradiation damage, then fast neutrons should be the primary focus. Injection rate was determined as the core target parameter.

[0022] Regarding the determination of neutron flux rate, this embodiment determines the required neutron flux rate level by back-calculation based on indicators such as irradiation metrology, damage level (e.g., dpa value), or isotope production rate required for the irradiation test, combined with parameters such as the nuclear reaction cross section of the sample material. For example, to achieve a certain dpa value within a predetermined period, the required fast neutron flux rate target value can be calculated; to produce a specific isotope, the required thermal neutron flux rate target value can be calculated.

[0023] Step S3: Based on the inherent structure of the original research reactor body, determine the adjustment strategy of the structural components around the irradiation channel based on the neutron field characteristics, and construct the neutron field accordingly. In this embodiment, the adjustment strategy includes adjusting one or more of the following: the arrangement position, component type, or arrangement quantity of the irradiated channel reactor internal components; wherein, the adjustment target of the irradiated channel reactor internal components is one or more of the following: fuel element, isotope target, beryllium assembly, aluminum assembly, or stainless steel assembly.

[0024] In some specific implementations, see Figure 3 As shown, four types of neutron fields, A, B, C, and D, were constructed by adjusting the types or quantities of fuel elements, isotope targets, beryllium assemblies, aluminum assemblies, or stainless steel assemblies arranged at different positions around the irradiation channel. (See attached diagram.) Figure 2 The typical neutron energy spectra of the four neutron fields are shown in Table 1 below: Table 1. Neutron field constructed by adjusting the type and quantity of in-core components in the local arrangement of irradiation channels.

[0025] As can be seen from Table 1 above, various types of neutron fields can be constructed by adjusting one or more of the fuel elements, isotope targets, beryllium assemblies, aluminum assemblies, or stainless steel assemblies arranged at different positions around the irradiation channel.

[0026] In another embodiment, the adjustment strategy includes adjusting the burn-out depth of the irradiation channel fuel element, the burn-out depth of which is adjusted from 0 to 50%. See also Figure 4 As shown, four burnup combinations of fuel elements with localized irradiation channels are presented. The neutron energy spectra of the irradiation channels under the four fuel element burnup combinations are shown in Table 2 below: Table 2. Neutron field constructed by adjusting the local arrangement of fuel element burnup in the irradiation channel

[0027] As can be seen from Table 2 above, various types of neutron fields can be constructed by adjusting the burnup depth of the fuel elements arranged around the irradiation channel.

[0028] In another embodiment, the adjustment strategy includes adjusting the number of fuel elements arranged in the irradiation channels, the number of fuel elements being adjusted from 25 to 80. See also Figure 2 and Figure 5 As shown, by adjusting the number of fuel elements loaded in the reactor core, the following results can be obtained: Figure 2 The core loading of the 80 fuel element boxes shown and as follows Figure 5The core loading of the 60 fuel elements shown below, and the neutron energy spectrum of the irradiated channels at an operating power of 80 MW for both types of fuel element loading, are shown in Table 3 below: Table 3. Neutron Field Constructed by Adjusting the Number of Core Fuel Elements

[0029] As can be seen from Table 3 above, when the operating power of the research reactor is constant, various types of neutron fields can be constructed by adjusting the number of fuel elements loaded in the reactor core.

[0030] In another implementation, the adjustment strategy includes adjusting the operating power of the research reactor, the adjustment range being 0 to 80 MW. See also Figure 2 As shown, without changing the number of fuel assemblies loaded in the reactor core, the neutron field of the irradiation channel can be altered by adjusting the operating power of the research reactor. Table 4 shows the neutron field of the irradiation channel when the operating power of the research reactor is 80MW, 60MW, and 40MW, as shown in Table 4 below: Table 4. Neutron field constructed by adjusting the operating power of the research reactor

[0031] As can be seen from Table 4 above, without changing the core fuel assembly loading, various types of neutron fields can be constructed by adjusting the operating power of the research reactor.

[0032] In another implementation, the adjustment strategy includes adjusting the lifting order of control rods within the research stack, wherein the adjustment target for the lifting order of control rods within the research stack is the compensation rod. In this embodiment, two lifting orders are provided, as shown in Table 5 below: Table 5. Neutron field constructed by adjusting the control rod lifting strategy

[0033] As shown in Table 5 above, without changing the number of fuel assemblies loaded in the reactor core and the operating power, the neutron field of the irradiation channel can be changed by adjusting the order of lifting the control rods of the research reactor.

[0034] In summary, by flexibly arranging movable core components and adjusting the fuel element loading, operating power, and control rod lifting strategy of the research reactor core, this invention can construct a specific neutron field required for irradiation experiments, providing a suitable irradiation environment for various irradiation experiments, and also providing a useful reference for the comprehensive and efficient utilization of the research reactor in the future.

[0035] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for constructing a neutron field for studying reactors, characterized in that, Includes the following steps: Obtain irradiation test parameters; Determine the neutron field characteristics corresponding to the irradiation test indicators, including the neutron energy spectrum and neutron flux rate; Based on the inherent structure of the original research reactor body, the adjustment strategy of the structural components around the irradiation channel is determined based on the neutron field characteristics. A neutron field is constructed based on the aforementioned adjustment strategy.

2. The method for constructing a neutron field for a research reactor as described in claim 1, characterized in that, The adjustment strategy includes adjusting one or more of the following: the arrangement position, component type, or arrangement quantity of components within the irradiation channel stack.

3. The method for constructing a neutron field for a research reactor as described in claim 2, characterized in that, The adjustment target of the irradiated channel reactor internals is one or more combinations of fuel elements, isotope targets, beryllium assemblies, aluminum assemblies, or stainless steel assemblies.

4. The method for constructing a neutron field for a research reactor as described in claim 3, characterized in that, The adjustment strategy includes adjusting the burn-out depth and / or the number of fuel elements in the irradiation channel.

5. The method for constructing a neutron field for a research reactor as described in claim 4, characterized in that, The fuel element's burn depth adjustment range is 0 to 50%.

6. The method for constructing a neutron field for a research reactor as described in claim 4, characterized in that, The number of fuel elements can be adjusted from 25 to 80.

7. The method for constructing a neutron field for a research reactor as described in any one of claims 1 to 6, characterized in that, The adjustment strategy includes adjusting the operating power of the research reactor.

8. The method for constructing a neutron field for a research reactor as described in claim 7, characterized in that, The operating power can be adjusted from 0 to 80 MW.

9. The method for constructing a neutron field for a research reactor as described in any one of claims 1 to 6, characterized in that, The adjustment strategy includes adjusting the lifting sequence of control rods within the research stack.

10. The method for constructing a neutron field for a research reactor as described in claim 9, characterized in that, The target of adjusting the lifting sequence of control rods within the reactor core is the compensation rod.

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