Plutonium inventory neutron monitoring method and device, critical safety assessment method and system

Abstract

The present application discloses a plutonium inventory neutron monitoring method and device, a critical safety assessment method and system, which relate to the technical field of nuclear industry. The monitoring method includes: obtaining a first spatial effect correction factor, a second spatial effect correction factor, and a third spatial effect correction factor, and determining the equivalent mass of plutonium-240 according to the first spatial effect correction factor, the second spatial effect correction factor, and the third spatial effect correction factor; determining the plutonium concentration of the solution system according to the equivalent mass. According to the embodiments of the present application, the method can improve the accuracy of plutonium inventory neutron monitoring.

Description

Technical Field

[0001] This application belongs to the technical field of nuclear industry, and specifically relates to a plutonium inventory neutron monitoring method and device, a critical safety assessment method and system. Background Art

[0002] In a system containing plutonium materials, the spontaneous fission neutrons released by the spontaneous fission of plutonium and the particles generated by the decay of plutonium react with nuclides such as N and O in the solution to release neutrons, which can cause induced fission and proliferation in the system. Eventually, some neutrons leak out and form monitoring neutron counts in the detection system outside the system. Therefore, the plutonium inventory information in the system can be inferred based on this neutron count rate.

[0003] The spontaneous fission and induced fission neutrons of plutonium have multiplicity, that is, a single spontaneous fission or induced fission will simultaneously release multiple indistinguishable neutrons, and the number of neutrons released by each spontaneous or induced fission follows a probability distribution and statistical law. The time coincidence method can be used to measure coincidence events, that is, two or more events that occur simultaneously or have a definite correlation in time within a certain time period.

[0004] Boehnel derived the "point model" equations for neutron multiplicity counting based on a plutonium metal system (see: LA-13422-M, Application guide to neutron multiplicity counting; Shi Xueming, Liu Cheng'an. Application research of coincidence counting in the measurement of plutonium properties [J]. Nuclear Physics Review. 2004.) as follows:

[0005] (1-1)

[0006] (2-1)

[0007] Wherein, represents the total neutron count rate, represents the coincidence neutron count rate, represents the detection efficiency, represents 240 the spontaneous fission rate of Pu (constant), represents 240 the equivalent mass of Pu, represents the neutron multiplication leakage coefficient, that is, the ratio of the number of leaked neutrons to the number of source neutrons in the system after the spontaneous fission neutrons and neutrons in the system are multiplied and finally leak out of the system, represents the ratio of the number of neutrons to the number of spontaneous fission neutrons. , denote 240 the first moment and the second moment of the spontaneous fission neutron multiplicity distribution of Pu, and denote the first moment and the second moment of the induced fission neutron multiplicity distribution, is the gate utilization factor.

[0008] The "point model" equations based on the plutonium metal system are based on the following assumptions:

[0009] (1) All induced fission neutrons are released almost simultaneously with the spontaneous fission neutrons and neutrons, without considering the length of the fission chain;

[0010] (2) It is assumed that the neutron detection efficiency and the fission probability are volume-uniform within the sample;

[0011] (3) It is assumed that the spontaneous fission neutrons and neutrons have the same energy spectrum. Therefore, the detection efficiency, the fission probability, and the induced fission multiplication are all the same;

[0012] (4) The probability of neutron capture without fission is negligible;

[0013] (5) The neutron multiplicity and the neutron energy are not correlated;

[0014] (6) The decay time of neutrons in the sample / detector is a single exponential decay.

[0015] In the prior art, the commonly used plutonium inventory neutron monitoring methods include: based on the "Boehnel" point model equations, and based on the fact that the probability of neutron capture without fission in the plutonium solution system cannot be ignored, and there are obvious differences in the energy spectra of spontaneous fission neutrons and neutrons, corrections for neutron absorption effects, corrections for the energy spectrum differences between neutrons and spontaneous fission neutrons, and corrections for the detection efficiency differences between induced fission neutrons and spontaneous fission neutrons are made. However, the above methods do not consider the spatial effects of the solution system, resulting in insufficient accuracy of plutonium inventory neutron monitoring. Summary of the Invention

[0016] The technical problem to be solved by this application is to address the above deficiencies in the prior art, and provide a plutonium inventory neutron monitoring method and device, a critical safety assessment method and system. Using this plutonium inventory neutron monitoring method, the determination of the equivalent mass of plutonium-240 considers the spatial effects to more accurately determine the equivalent mass of plutonium-240 so as to determine the plutonium concentration of the solution system according to the equivalent mass and improve the accuracy of plutonium inventory neutron monitoring.

[0017] In a first aspect, an embodiment of the present application provides a plutonium inventory neutron monitoring method, which is applied to a plutonium-containing solution system. The method includes:

[0018] Obtain a first spatial effect correction factor , a second spatial effect correction factor and a third spatial effect correction factor , where the first spatial effect correction factor is the spatial effect correction factor of the spontaneous fission neutron multiplication leakage coefficient, the second spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the spontaneous fission neutron source, and the third spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the neutron source;

[0019] Determine the equivalent mass of plutonium-240 according to the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor ;

[0020] Determine the plutonium concentration of the solution system according to the equivalent mass .

[0021] In some embodiments of the first aspect, the solution system includes sub-regions, where

[0022] is a positive integer; Obtain the first spatial effect correction factor

[0023] , specifically including: Obtain the first type of multiplication leakage coefficient and the first type of detection efficiency of the solution system, and the first multiplication leakage coefficients, the

[0024] first detection efficiencies and The first proliferation leakage coefficient, The first detection efficiency and volume, determine the first spatial effect correction factor .

[0025] In some implementations of the first aspect, according to the first type of proliferation leakage coefficient, the first type of detection efficiency, The first proliferation leakage coefficient, The first detection efficiency and volume, determine the first spatial effect correction factor , specifically including:

[0026] The first-type proliferation leakage coefficient, the first-type detection efficiency, The first proliferation leakage coefficient, The first detection efficiency and Substitute the volume into formula (1) to calculate and obtain the first space effect correction factor ;

[0027] Formula (1) includes:

[0028] (1)

[0029] in, Indicates The first detection efficiency of each sub-area; Indicates The first proliferation leakage coefficient of each sub-area; Indicates The volume of each sub-region; represents the total volume of the solution system, that is The sum of the volumes; represents the first type of detection efficiency; represents the first type proliferation leakage coefficient.

[0030] In some embodiments of the first aspect, the solution system comprises Sub-districts, is a positive integer;

[0031] Get the second space effect correction factor , specifically including:

[0032] Obtain the first-type proliferation leakage coefficient and the first-type detection efficiency of the solution system, and Sub-district Volume, The first induced fission reaction rate share, The first net growth factor, The second proliferation leakage coefficient, and a second detection efficiency; the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, and the first induced fission reaction rate fraction is the spontaneous fission neutron source in the sub-region in the sub-region causing the induced fission reaction rate fraction, the first net multiplication coefficient is the net multiplication coefficient of the spontaneous fission neutron source in the sub-region the second multiplication leakage coefficient is the multiplication leakage coefficient of the induced fission neutrons in the sub-region and the second detection efficiency is the detection efficiency of the induced fission neutrons in the sub-region The volume, the first net multiplication coefficient, the second multiplication leakage coefficient, and the second detection efficiency respectively correspond one-to-one to the sub-region, and one sub-region corresponds to a first induced fission reaction rate fraction and are all positive integers;

[0033] According to the first type of multiplication leakage coefficient, the first type of detection efficiency, a volume, a first induced fission reaction rate fraction, a first net multiplication coefficient, a second multiplication leakage coefficient, and a second detection efficiency, determine the second space effect correction factor .

[0034] In some embodiments of the first aspect, according to the first type of multiplication leakage coefficient, the first type of detection efficiency, a volume, a first induced fission reaction rate fraction, a first net multiplication coefficient, a second multiplication leakage coefficient, and a second detection efficiency, determine the second space effect correction factor , specifically including:

[0035] Substitute the first type of multiplication leakage coefficient, the first type of detection efficiency, a volume, a first induced fission reaction rate fraction, a first net multiplication coefficient, a second multiplication leakage coefficient, and a second detection efficiency into formula (2), and calculate to obtain the second space effect correction factor ;

[0036] Formula (2) includes:

[0037] (2)

[0038] Among them, represents the volume of the th sub-region; represents the total volume of the solution system, that is, the sum of the volumes; represents the first type of detection efficiency; represents the first type of breeding leakage coefficient; represents the share of the first induced fission reaction rate; represents the second detection efficiency; represents the second breeding leakage coefficient;

[0039] In some embodiments of the first aspect, the solution system includes sub-regions, where

[0040] Obtain the third space effect correction factor , specifically including:

[0041] Obtain the first type of breeding leakage coefficient and the first type of detection efficiency of the solution system, and the volumes of the sub-regions, the shares of the second induced fission reaction rates of the sub-regions, the second net breeding coefficients of the sub-regions, the second breeding leakage coefficients of the sub-regions, and the second detection efficiencies of the sub-regions; the first type of breeding leakage coefficient is the breeding leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the share of the second induced fission reaction rate is the share of the induced fission reaction rate caused by the neutron source of the sub-region in the sub-region, the second net breeding coefficient is the net breeding coefficient of the and neutron source of the

[0042] According to the first type of breeding leakage coefficient, the first type of detection efficiency, a volume, a second induced fission reaction rate fraction, a second net multiplication factor, a second multiplication leakage factor, and a second detection efficiency, to determine a third space effect correction factor .

[0043] In some embodiments of the first aspect, according to a first type of multiplication leakage factor, a first type of detection efficiency, a volume, a second induced fission reaction rate fraction, a second net multiplication factor, a second multiplication leakage factor, and a second detection efficiency, to determine a third space effect correction factor , specifically including:

[0044] Substitute the first type of multiplication leakage factor, the first type of detection efficiency, a volume, a second induced fission reaction rate fraction, a second net multiplication factor, a second multiplication leakage factor, and a second detection efficiency into formula (3) to calculate the third space effect correction factor ;

[0045] Formula (3) includes:

[0046] (3)

[0047] wherein, represents the volume of the th sub-region; represents the total volume of the solution system, i.e., the sum of the volumes; represents the first type of detection efficiency; represents the first type of multiplication leakage factor; represents the second induced fission reaction rate fraction; represents the second detection efficiency; represents the second multiplication leakage factor; represents the second net multiplication factor.

[0048] In some embodiments of the first aspect, according to the first space effect correction factor , the second space effect correction factor and the third space effect correction factor , determine the equivalent mass of plutonium-240 , specifically including:

[0049] Obtain the first information of the solution system, where the first information includes the total neutron count rate , the coincidence neutron count rate , the spontaneous fission rate of plutonium-240 , the detection efficiency of the first type , the detection efficiency of the second type , the first type of breeding leakage coefficient , the second type of breeding leakage coefficient , the first type of first moment , the first type of second moment , the second type of first moment , the second type of second moment and the gate utilization factor ; among them, the detection efficiency of the first type is the detection efficiency of the leakage neutrons when the solution system has only a spontaneous fission neutron source; the detection efficiency of the second type is the detection efficiency of the leakage neutrons when the solution system has only neutron source; the first type of breeding leakage coefficient is the breeding leakage coefficient of the solution system when the solution system has only a spontaneous fission neutron source; the second type of breeding leakage coefficient is the breeding leakage coefficient of the solution system when the solution system has only neutron source; the first type of first moment is the first moment of the spontaneous fission neutron multiplicity distribution in the solution system; the first type of second moment is the second moment of the spontaneous fission neutron multiplicity distribution in the solution system; the second type of first moment is the first moment of the induced fission neutron multiplicity distribution in the solution system; the second type of second moment is the second moment of the induced fission neutron multiplicity distribution in the solution system;

[0050] Determine the equivalent mass of plutonium-240 according to the first information, the first space effect correction factor , the second space effect correction factor , and the third space effect correction factor .

[0051] In some embodiments of the first aspect, determine the equivalent mass of plutonium-240 according to the first information, the first space effect correction factor , the second space effect correction factor , and the third space effect correction factor , specifically including:

[0052] Substitute the first information, the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor into Equation (4) to calculate the equivalent mass of plutonium-240 ;

[0053] Equation (4) includes:

[0054] (4).

[0055] In some embodiments of the first aspect, Equation (4) is obtained from a system of spatial model equations, and the system of spatial model equations includes Equation (5) and Equation (6). Equation (5) includes:

[0056] (5)

[0057] where represents the ratio of the number of neutrons to the number of spontaneous fission neutrons;

[0058] Equation (6) includes:

[0059] (6).

[0060] In some embodiments of the first aspect, based on the equivalent mass , determine the plutonium concentration of the solution system, which specifically includes:

[0061] Obtain the first mass percentage of plutonium-238 , the second mass percentage of plutonium-240 , the third mass percentage of plutonium-242 ;

[0062] Substitute the equivalent mass , the first mass percentage , the second mass percentage and the third mass percentage into Equation (7) to calculate the total plutonium mass of the solution system;

[0063] Equation (7) includes:

[0064] (7)

[0065] Based on the total plutonium mass , determine the plutonium concentration of the solution system.

[0066] Based on the same inventive concept, in a second aspect, an embodiment of the present application further provides a critical safety assessment method, which is applied to a plutonium-containing solution system. The method includes:

[0067] For the plutonium inventory neutron monitoring method according to any one of the first aspects, determine the plutonium concentration of the solution system;

[0068] Evaluate the critical safety of the solution system using the plutonium concentration.

[0069] Based on the same inventive concept, in a third aspect, an embodiment of the present application further provides a plutonium inventory neutron monitoring device, which is applied to a solution system containing plutonium. The device includes:

[0070] A first acquisition module for acquiring a first spatial effect correction factor , a second spatial effect correction factor and a third spatial effect correction factor , where the first spatial effect correction factor is the spatial effect correction factor of the spontaneous fission neutron multiplication leakage coefficient, and the second spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the spontaneous fission neutron source, and the third spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the neutron source;

[0071] A first determination module, connected to the first acquisition module, for determining the equivalent mass of plutonium-240 according to the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor ;

[0072] A second determination module, connected to the first determination module, for determining the plutonium concentration of the solution system according to the equivalent mass .

[0073] In some embodiments of the third aspect, the solution system includes sub-regions, where

[0074] is a positive integer;

[0075] The first acquisition module is specifically configured to: acquire the first type of multiplication leakage coefficient and the first type of detection efficiency of the solution system, and the first multiplication leakage coefficients, A volume, the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the first multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the sub-region only, the first detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the sub-region only, the first multiplication leakage coefficient, the first detection efficiency and the volume respectively correspond to the sub-regions one by one;

[0076] According to the first type of multiplication leakage coefficient, the first type of detection efficiency, a first multiplication leakage coefficient, a first detection efficiency and a volume, determine the first space effect correction factor .

[0077] In some embodiments of the third aspect, the solution system includes sub-regions, being a positive integer;

[0078] The first acquisition module is specifically used for:

[0079] Acquire the first type of multiplication leakage coefficient and the first type of detection efficiency of the solution system, and the volumes, the first induced fission reaction rate fractions, the first net multiplication coefficients, the second multiplication leakage coefficients, and the second detection efficiencies of sub-regions; the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the first induced fission reaction rate fraction is the fraction of the induced fission reaction rate caused by the spontaneous fission neutron source in sub-region in sub-region , the first net multiplication coefficient is the net multiplication coefficient of the spontaneous fission neutron source in sub-region , the second multiplication leakage coefficient is the multiplication leakage coefficient of the induced fission neutrons in sub-region , the second detection efficiency is the detection efficiency of the induced fission neutrons in sub-region a first induced fission reaction rate fraction, and are both positive integers;

[0080] According to the first type of multiplication leakage coefficient, the first type of detection efficiency, One volume, One first induced fission reaction rate fraction, One first net multiplication factor, One second multiplication leakage coefficient, and One second detection efficiency to determine a second space effect correction factor .

[0081] In some embodiments of the third aspect, the solution system includes M sub-regions, where M is a positive integer;

[0082] A first acquisition module, specifically configured to:

[0083] Acquire a first type of multiplication leakage coefficient and a first type of detection efficiency of the solution system, and the One volume, One second induced fission reaction rate fraction, One second net multiplication factor, One second multiplication leakage coefficient, and One second detection efficiency of M sub-regions; the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the second induced fission reaction rate fraction is the induced fission reaction rate fraction caused by the neutron source in sub-region in sub-region , the second net multiplication factor is the net multiplication factor of the neutron source in sub-region , the second multiplication leakage coefficient is the multiplication leakage coefficient of the induced fission neutrons in sub-region , the second detection efficiency is the detection efficiency of the induced fission neutrons in sub-region , the volume, the second net multiplication factor, the second multiplication leakage coefficient, and the second detection efficiency respectively correspond to the sub-regions one by one, and one sub-region corresponds to One second induced fission reaction rate fraction, and both are positive integers;

[0084] According to the first type of multiplication leakage coefficient, the first type of detection efficiency, One volume, One second induced fission reaction rate fraction, One second net multiplication factor, One second multiplication leakage coefficient, and One second detection efficiency, determine a third space effect correction factor .

[0085] Based on the same inventive concept, in a fourth aspect, an embodiment of the present application further provides a criticality safety assessment system, which is applied to a plutonium-containing solution system. The criticality safety assessment system includes:

[0086] The plutonium inventory neutron monitoring device according to any one of the third aspects, which is used to determine the plutonium concentration of the solution system;

[0087] An evaluation device, connected to the plutonium inventory neutron monitoring device, which is used to evaluate the criticality safety of the solution system by using the plutonium concentration.

[0088] According to the plutonium inventory neutron monitoring method and device, and the criticality safety assessment method and system provided by the embodiments of the present application, by combining the first spatial effect correction factor , the second spatial effect correction factor , and the third spatial effect correction factor , the equivalent mass of plutonium-240 is determined , that is, the first spatial effect correction factor , the second spatial effect correction factor , and the third spatial effect correction factor are introduced to consider the spatial effect correction of induced fission neutron multiplication leakage and neutron net multiplication, so that the equivalent mass of plutonium-240 takes into account the spatial effect, and the equivalent mass of plutonium-240 is more accurately determined . Thus, according to the equivalent mass , the plutonium concentration of the solution system is determined, and the accuracy of plutonium inventory neutron monitoring can be improved. Description of the Drawings

[0089] Figure 1 Shows a schematic flow chart of a plutonium inventory neutron monitoring method provided by an embodiment of the present application;

[0090] Figure 2 Shows a vertical sectional view of the device of an implementation case of the plutonium inventory neutron monitoring method provided by an embodiment of the present application;

[0091] Figure 3 Shows a horizontal sectional view of the device of an implementation case of the plutonium inventory neutron monitoring method provided by an embodiment of the present application. Detailed Embodiments

[0092] To enable those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below with reference to the drawings and embodiments.

[0093] The features and exemplary embodiments of various aspects of the present application will be described in detail below. To make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present application and are not configured to limit the present application. For those skilled in the art, the present application can be implemented without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0094] It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, elements defined by the statement "comprising..." do not preclude the existence of additional identical elements in the process, method, article or device comprising the said elements.

[0095] It should be understood that the term "and / or" used herein is only an associative relationship describing associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally represents an "or" relationship between the associated objects before and after. Embodiment 1

[0096] The plutonium inventory neutron monitoring method provided by the embodiments of the present application can be executed by a plutonium inventory neutron monitoring device, an electronic device, etc. The following takes the case where the plutonium inventory neutron monitoring method is executed by an electronic device for illustration.

[0097] The plutonium inventory neutron monitoring method provided by the embodiments of the present application can be applied to the post-treatment process of spent fuel.

[0098] It should be noted that the plutonium inventory neutron monitoring method provided by the embodiments of the present application can be applied to a plutonium-containing solution system, especially a large-volume solution system.

[0099] As Figure 1 shown, the plutonium inventory neutron monitoring method provided by the embodiments of the present application may include steps S110 to S130.

[0100] S110. Obtain the first space effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor , where the first spatial effect correction factor is the spatial effect correction factor of the spontaneous fission neutron multiplication leakage coefficient, and the second spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the spontaneous fission neutron source. The third spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the neutron source.

[0101] S120. According to the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor , determine the equivalent mass of plutonium-240.

[0102] S130. According to the equivalent mass , determine the plutonium concentration of the solution system.

[0103] According to the plutonium inventory neutron monitoring method provided by the embodiments of the present application, by combining the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor , determine the equivalent mass of plutonium-240. That is, the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor are introduced to consider the spatial effect correction of induced fission neutron multiplication leakage and neutron net multiplication, so that the determination of the equivalent mass of plutonium-240 takes into account the spatial effect, and the equivalent mass of plutonium-240 can be determined more accurately. Thus, according to the equivalent mass, the plutonium concentration of the solution system is determined, and the accuracy of plutonium inventory neutron monitoring can be improved.

[0104] The specific implementation methods of the above steps are introduced below.

[0105] In step S110, plutonium-240 is 240 the Pu nuclide.

[0106] In some embodiments, the electronic device may pre-store the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor for subsequent direct invocation.

[0107] In some other embodiments, the solution system includes sub-regions, where is a positive integer;

[0108] Obtain the first spatial effect correction factor , specifically including:

[0109] Obtain the first type of multiplication leakage coefficient and the first type of detection efficiency of the solution system, and the first multiplication leakage coefficients, the first detection efficiencies, and

[0110] the first multiplication leakage coefficients, the first detection efficiencies, and the

[0111] volumes of the sub-regions, where the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the first multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the sub-region only, the first detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the sub-region only, and the first multiplication leakage coefficient, the first detection efficiency, and the volume correspond to the sub-regions one by one; sub-regions.

[0112] Exemplarily, the sub-regions included in the solution system can be pre-stored in an electronic device for subsequent direct call, or the solution system can be divided according to the three-dimensional structure of the solution system to obtain sub-regions.

[0113] Exemplarily, the first multiplication leakage coefficients and

[0114] the An individual volume can be pre-stored in the electronic device for subsequent direct invocation.

[0115] It should be noted that Any two of the individual volumes can be equal or unequal, and no limitation is made here; The value of can be set according to the actual situation and no limitation is made here. For example, The value of can be 3, 5, 10, etc.

[0116] In some examples, according to the first type of multiplication leakage coefficient, the first type of detection efficiency, the first multiplication leakage coefficients, the first detection efficiencies, and the individual volumes, the first space effect correction factor is determined, specifically including:

[0117] Substitute the first type of multiplication leakage coefficient, the first type of detection efficiency, the first multiplication leakage coefficients, the first detection efficiencies, and the individual volumes into formula (1) for calculation to obtain the first space effect correction factor ;

[0118] Formula (1) includes:

[0119] (1)

[0120] Wherein, represents the first detection efficiency of the th sub-region; represents the first multiplication leakage coefficient of the th sub-region; represents the volume of the th sub-region; represents the volume of the th sub-region; represents the th sub-region; represents the volume of the th sub-region; represents the total volume of the solution system, that is, the sum of the individual volumes; represents the first type of detection efficiency; represents the first type of multiplication leakage coefficient.

[0121] That is to say, the space effect correction factor of the spontaneous fission neutron multiplication leakage coefficient considers the volume weighting of the power value of the first multiplication leakage coefficient and the spatial distribution of the first detection efficiency.

[0122] In some other embodiments, the solution system includes sub-regions, is a positive integer;

[0123] Obtain the second space effect correction factor specifically including:

[0124] Obtain the first type of multiplication leakage coefficient and the first type of detection efficiency of the solution system, and the individual volumes, the first induced fission reaction rate fractions, the first net multiplication coefficients, the second multiplication leakage coefficients, and the second detection efficiencies; the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the first induced fission reaction rate fraction is the fraction of the induced fission reaction rate caused by the spontaneous fission neutron source in sub-region in sub-region the and are all positive integers;

[0125] Determine the second spatial effect correction factor according to the first type of multiplication leakage coefficient, the first type of detection efficiency, the individual volumes, the first induced fission reaction rate fractions, the

[0126] Exemplarily, the first induced fission reaction rate fractions, the first net multiplication coefficients,

[0127] In some examples, according to the first type of multiplication leakage coefficient, the first type of detection efficiency, the individual volumes, the a second multiplication leakage coefficient, and a second detection efficiency, to determine a second spatial effect correction factor , specifically including:

[0128] Substitute the first type of multiplication leakage coefficient, the first type of detection efficiency, a volume, a first induced fission reaction rate fraction, a first net multiplication coefficient, a second multiplication leakage coefficient, and a second detection efficiency into formula (2) to calculate the second spatial effect correction factor ;

[0129] Formula (2) includes:

[0130] (2)

[0131] Wherein, represents the volume of the th sub-region; represents the total volume of the solution system, that is, the sum of volumes; represents the first type of detection efficiency; represents the first type of multiplication leakage coefficient; represents the second detection efficiency; represents the second multiplication leakage coefficient; represents the first net multiplication coefficient.

[0132] That is to say, the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the spontaneous fission neutron source takes into account the distribution of the first induced fission reaction rate generated by the spontaneous fission neutron source in the solution system, and the weighting of the spontaneous fission neutron source, and at the same time takes into account the spatial distribution of the second detection efficiency, and the difference in the neutron energy spectra between the spontaneous fission neutron source and the induced fission source.

[0133] It should be noted that the subscript represents the induced fission neutron, represents the average value of

[0134] In some other embodiments, the solution system includes sub-regions, is a positive integer;

[0135] Obtain a third spatial effect correction factor , specifically including:

[0136] Obtain the first-type proliferation leakage coefficient and the first-type detection efficiency of the solution system, and Sub-district Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and The second detection efficiency; the first type of proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only spontaneous fission neutron source in the solution system, and the second induced fission reaction rate share is the sub-area of Neutron source in sub-area The induced fission reaction rate share caused by the second net proliferation coefficient is the sub-area of The net multiplication coefficient of the neutron source, the second multiplication leakage coefficient is the sub-area The multiplication leakage coefficient of induced fission neutrons, the second detection efficiency is the sub-area The detection efficiency of induced fission neutrons, volume, second net multiplication coefficient, second multiplication leakage coefficient and second detection efficiency correspond to sub-areas one by one, and one sub-area corresponds to The second induced fission reaction rate fraction, and All are positive integers;

[0137] According to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and The second detection efficiency determines the third spatial effect correction factor .

[0138] For example, The second induced fission reaction rate fraction, Each second net growth factor can be calculated using a three-dimensional Monte Carlo program.

[0139] For example, The second induced fission reaction rate fraction, Each second net proliferation coefficient can be pre-stored in the electronic device for subsequent direct retrieval.

[0140] In some examples, according to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The second induced fission reaction rate fraction, a second net multiplication factor, a second multiplication leakage factor, and a second detection efficiency to determine a third space effect correction factor , specifically including:

[0141] Substitute the first type of multiplication leakage factor, the first type of detection efficiency, a volume, a second induced fission reaction rate fraction, a second net multiplication factor, a second multiplication leakage factor, and a second detection efficiency into formula (3) to calculate the third space effect correction factor ;

[0142] Formula (3) includes:

[0143] (3)

[0144] Wherein, represents the volume of the th sub-region; represents the total volume of the solution system, that is, the sum of volumes; represents the first type of detection efficiency; represents the first type of multiplication leakage factor; represents the second induced fission reaction rate fraction; represents the second detection efficiency; represents the second multiplication leakage factor.

[0145] That is to say, the space effect correction factor of the induced fission neutron multiplication leakage factor caused by the neutron source considers the induced fission reaction rate distribution generated by the neutron source in the solution system, and the neutron source weighting, and at the same time considers the spatial distribution of the second detection efficiency, and the difference between the neutron energy spectra of the neutron source and the induced fission source.

[0146] In the embodiments of the present application, the space effect correction factor of the induced fission neutron multiplication leakage factor considers the induced fission reaction rate distribution generated by the initial source in the solution system and the initial source distribution weighting, and at the same time considers the spatial distribution of the detection efficiency and the difference between the neutron energy spectra of the initial source and the induced fission source. The calculation formula is as follows:

[0147] (8)

[0148] Where the subscript = 1 , 2 respectively represent that the initial source is a spontaneous fission neutron source or a neutron source, and the subscript represents an induced fission neutron, is the volume of the sub-region of the solution system ; is the total volume of the solution system, is the sub-region the share of the induced fission reaction rate caused by the initial source neutrons in the sub-region (i.e., the first induced fission reaction rate share or the second induced fission reaction rate share), is the net multiplication factor of the initial source neutrons in the sub-region (i.e., the first net multiplication factor or the second net multiplication factor), is the multiplication leakage coefficient of the induced fission neutrons in the sub-region (i.e., the second multiplication leakage coefficient), is the detection efficiency of the induced fission neutrons in the sub-region (i.e., the second detection efficiency).

[0149] In step S120, after the electronic device obtains the first space effect correction factor , the second space effect correction factor and the third space effect correction factor , it can also determine the equivalent mass of plutonium-240 according to the first space effect correction factor , the second space effect correction factor and the third space effect correction factor .

[0150] In some possible implementation manners, according to the first space effect correction factor , the second space effect correction factor and the third space effect correction factor , determine the equivalent mass of plutonium-240, specifically including:

[0151] Obtain the first information of the solution system, and the first information includes the total neutron count rate , the coincidence neutron count rate , the spontaneous fission rate of plutonium-240 , the first type of detection efficiency , the second type of detection efficiency , the first type of multiplication leakage coefficient , the second type of multiplication leakage coefficient , the first type of first moment , the first type of second moment , the second type of first moment , the second type of second moment and the gate utilization factor ; where the detection efficiency of the first type is the detection efficiency of the leakage neutrons when the solution system has only a spontaneous fission neutron source; the detection efficiency of the second type is the detection efficiency of the leakage neutrons when the solution system has only neutron source; the multiplication leakage coefficient of the first type is the multiplication leakage coefficient of the solution system when the solution system has only a spontaneous fission neutron source; the multiplication leakage coefficient of the second type is the multiplication leakage coefficient of the solution system when the solution system has only neutron source; the first type of first moment is the first moment of the spontaneous fission neutron multiplicity distribution in the solution system; the first type of second moment is the second moment of the spontaneous fission neutron multiplicity distribution in the solution system; the second type of first moment is the first moment of the induced fission neutron multiplicity distribution in the solution system; the second type of second moment is the second moment of the induced fission neutron multiplicity distribution in the solution system;

[0152] According to the first information, the first space effect correction factor , the second space effect correction factor and the third space effect correction factor , determine the equivalent mass of plutonium-240 .

[0153] Exemplarily, the total neutron count rate , whose unit is counts per second (cps), and its value is the measured value or the value simulated by a three-dimensional Monte Carlo program; the coincidence neutron count rate , whose unit is cps, and its value is the measured value, or the value simulated by a three-dimensional Monte Carlo program; the spontaneous fission rate , whose unit is fissions per gram per second (fission / (g.s)), is 240 the inherent characteristic constant of the Pu nuclide, independent of the solution system, and its value is approximately equal to 475 fission / (g.s); is the gate utilization factor of the neutron detection system, indicating the coincidence count g when the gate duration is t D g and the coincidence count D ∞ when the gate duration is ∞.

[0154] As an example, the first piece of information can be pre-stored in the electronic device for subsequent direct invocation.

[0155] As another example, the total neutron count rate and the coincidence neutron count rate can both be obtained by measurement, or both can be calculated by a three-dimensional Monte Carlo program; the first type of detection efficiency and the second type of detection efficiency and the first type of breeding leakage coefficient and the second type of breeding leakage coefficient and the second type of first moment and the second type of second moment and the gate utilization factor can all be calculated by a three-dimensional Monte Carlo program.

[0156] It should be noted that the first type of first moment and the first type of second moment are both constants and have nothing to do with the solution system.

[0157] In some examples, according to the first piece of information, the first space effect correction factor and the second space effect correction factor and the third space effect correction factor , the equivalent mass of plutonium-240 is determined, specifically including:

[0158] Substitute the first piece of information, the first space effect correction factor and the second space effect correction factor and the third space effect correction factor into formula (4) to calculate the equivalent mass of plutonium-240 ;

[0159] Formula (4) includes:

[0160] (4).

[0161] In some examples, formula (4) is obtained from a space model system of equations, and the space model system of equations includes formula (5) and formula (6). Formula (5) includes:

[0162] (5)

[0163] where represents the ratio of the number of neutrons to the number of spontaneous fission neutrons;

[0164] Formula (6) includes:

[0165] (6).

[0166] Exemplarily, Equation (5) can be arranged into an expression, and then substitute this expression into Equation (6) and arrange to obtain the above Equation (4).

[0167] Exemplarily, the value of can be pre-stored in an electronic device for subsequent direct call.

[0168] The passive neutron real-time online monitoring method for plutonium inventory in a solution system based on a spatial model provided in the embodiments of the present application (i.e., the plutonium inventory neutron monitoring method) is based on the "point model" equations and their improved versions, considers the differences between the initial source distribution and the induced fission source distribution, corrects the spatial effects of induced fission neutron multiplication leakage and neutron net multiplication, and at the same time distinguishes spontaneous fission neutrons and the differences in neutrons in terms of detection efficiency, multiplication leakage, etc. Finally, a spatial model equation set that considers spatial effects and is applicable to the solution system is obtained. After considering the spatial effects, it can more accurately reflect the measurement results of the neutron count rate of the monitoring system outside the large-volume plutonium solution system, and thus more accurately estimate the plutonium inventory in the system. This method considers the characteristics of the induced fission neutron source varying with space, solves the spatial effects of induced fission neutron multiplication leakage and neutron net multiplication in a large-volume solution system, and realizes the neutron passive non-destructive monitoring and analysis of the plutonium content in a large-volume solution system. It is an advanced and engineering-feasible method for monitoring the plutonium content in a solution system.

[0169] The embodiments of the present application effectively solve the problem of the spatial effects of the net multiplication and multiplication leakage coefficient in the method for monitoring the plutonium content in a large-volume solution system, introduce the first spatial effect correction factor , to consider the volume weighting of the power value of the spontaneous fission neutron multiplication leakage coefficient, introduce the second spatial effect correction factor and the third spatial effect correction factor , to consider the induced fission reaction rate distribution and the initial source distribution weighting, and at the same time consider the spatial distribution of the detection efficiency and the differences in the neutron energy spectra of the initial source and the induced fission source, so that the plutonium content monitoring based on the spatial model equation set can well predict the neutron count rate of the large-volume solution system, and thus is applicable to the calculation of the plutonium content in the large-volume solution system, solving the problem of uneven spatial distribution of the multiplication leakage coefficient.

[0170] In some other embodiments, the equivalent mass can also be calculated through Equation (9). Equation (9) includes:

[0171] (9)

[0172] In step S130, the electronic device, according to the first space effect correction factor , the second space effect correction factor , and the third space effect correction factor , determines the equivalent mass of plutonium-240 . After that, the plutonium concentration of the solution system can also be determined according to the equivalent mass .

[0173] In some embodiments, determining the plutonium concentration of the solution system according to the equivalent mass specifically includes:

[0174] Obtaining the first mass percentage of plutonium-238 , the second mass percentage of plutonium-240 , and the third mass percentage of plutonium-242 ;

[0175] Substitute the equivalent mass , the first mass percentage , the second mass percentage , and the third mass percentage into formula (7) to calculate the total plutonium mass of the solution system ;

[0176] Formula (7) includes:

[0177] (7)

[0178] Determine the plutonium concentration of the solution system according to the total plutonium mass .

[0179] Exemplarily, the first mass percentage , the second mass percentage , and the third mass percentage are pre-stored in the electronic device for subsequent direct call.

[0180] Exemplarily, the product of the total plutonium mass and the total volume of the solution system is determined as the plutonium concentration of the solution system.

[0181] The plutonium inventory passive neutron real-time online monitoring method (i.e., the plutonium inventory neutron monitoring method) provided by the embodiments of the present application will be described below in combination with a specific embodiment.

[0182] The space model equations based on are as follows:

[0183] (5)

[0184] (6)

[0185] In the formula:

[0186] represents the total neutron count rate, in cps, which is a measured value or a value simulated by a three-dimensional Monte Carlo program;

[0187] represents the coincidence neutron count rate, in cps, which is a measured value or a value simulated by a three-dimensional Monte Carlo program;

[0188] represents 240 the spontaneous fission rate of Pu, in fission / (g·s), which is 240 the inherent characteristic constant of the Pu nuclide;

[0189] represents the detection efficiency of the monitoring system for leakage neutrons when there is only a spontaneous fission neutron source;

[0190] represents when there is only a neutron source, the detection efficiency of the monitoring system for leakage neutrons;

[0191] represents the multiplication leakage coefficient of the system when there is only a spontaneous fission neutron source in the solution system;

[0192] represents when there is only a neutron source in the solution system, the multiplication leakage coefficient of the system;

[0193] and represent the first moment and the second moment of the spontaneous fission neutron multiplicity distribution in the solution system;

[0194] and represent the first moment and the second moment of the induced fission neutron multiplicity distribution in the solution system;

[0195] is the gate utilization factor of the neutron detection system, representing the coincidence count g at the gate duration of t D g compared with the coincidence count D ∞ at the gate duration of ∞;

[0196] represents 240 the equivalent mass of Pu;

[0197] is the spatial effect correction factor for the spontaneous fission neutron multiplication leakage coefficient;

[0198] 、 is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient;

[0199] Based on the total neutron count rate and the coincidence neutron count rate, that is, formula (5) and formula (6), the 240 Pu equivalent mass formula can be derived as follows:

[0200] (4)

[0201] If only based on the total neutron count rate, that is, formula (5), the 240 Pu equivalent mass formula can also be derived as follows:

[0202] (9)

[0203] Using formula (4) or formula (9), the can be solved by the iterative method. Further, the total plutonium mass is obtained as follows:

[0204] (7)

[0205] Among them, 、 、 are respectively 238 Pu, 240 Pu, 242 Pu mass percentages in plutonium; combined with the volume of the solution, information such as plutonium concentration can be further obtained.

[0206] Furthermore, for the real-time on-line monitoring method of plutonium inventory in the solution system based on the spatial model equations as described above, the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient takes into account the induced fission reaction rate distribution generated by the initial source in the solution system and the weighting of the initial source distribution, and at the same time takes into account the spatial distribution of the detection efficiency and the difference in neutron energy spectra between the initial source and the induced fission source. The calculation formula is as follows:

[0207] (8)

[0208] Among them, the subscript = 1 , 2 respectively represent that the initial source is a spontaneous fission neutron source or neutron source, the subscript represents the induced fission neutron, is the volume of the sub-region of the solution system, is the total volume of the solution system, is the sub-region The initial source neutrons in the sub-region The share of the induced fission reaction rate caused For the sub-region The net multiplication factor of the initial source neutrons For the sub-region The multiplication leakage coefficient of the induced fission neutrons For the sub-region The detection efficiency of the induced fission neutrons. The spatial effect correction factor of the spontaneous fission neutrons considers the volume weighting of the power value of the multiplication leakage coefficient and the spatial distribution of the detection efficiency. The calculation formula is as follows:

[0209] (1)

[0210] The solution system is divided into multiple sub-regions, and the three-dimensional Monte Carlo program is used to calculate and statistically analyze the net multiplication factor, multiplication leakage coefficient, neutron detection efficiency, etc. of the induced fission source for each sub-region, as well as the multiplication leakage coefficient, neutron detection efficiency, etc. of the spontaneous fission neutrons, and then calculate the corresponding spatial correction factors according to formula (8) and formula (1).

[0211] Furthermore, for the above solution system plutonium inventory passive neutron real-time online monitoring method based on the spatial model (i.e., the plutonium inventory neutron monitoring method), wherein, the first moment and the second moment (i.e., the second type of first moment and the second type of second moment ) of the induced fission neutron multiplicity distribution caused by the spontaneous fission neutrons in the solution system, the detection efficiency (i.e., the first type of detection efficiency ) of the neutron detection system for the leakage neutrons when only considering the spontaneous fission neutrons, and the gate utilization factor can all be calculated using the three-dimensional Monte Carlo program under typical large-volume solution concentrations and isotope mass ratios.

[0212] The embodiment of the present application is a solution system plutonium inventory passive neutron real-time online monitoring method based on the spatial model equations (i.e., the plutonium inventory neutron monitoring method), including processes such as the calculation of the overall system parameters, the calculation of the spatial effect correction factor, and the final estimation and solution of the plutonium inventory using the spatial model equations.

[0213] To simplify the sample partition calculation, it is assumed that the sample to be measured is a spherical plutonium solution with a radius of R, outside the solution is a spherical stainless steel container with a wall thickness of 3 millimeters (mm), and outside the container is a cylindrical measuring device. There are 18 3 He detectors arranged in a circular pattern inside the polyethylene of the cylindrical measuring device. Five cases with the spherical plutonium solution radius R = 10 centimeters (cm), 15 cm, 20 cm, 25 cm, and 30 cm are analyzed. The entire plutonium inventory neutron monitoring device is as shown in Figure 2 andFigure 3 As shown Figure 2 is a vertical sectional view of the device, Figure 3 and is a horizontal sectional view of the device. Where 1 is the solution, 2 is the stainless-steel container, 3 is 3 He detector (4 atmospheres), 4 is polyethylene, 5 is an aluminum (Al) layer, and 6 is a cadmium (Cd) lining.

[0214] 240 The spontaneous fission rate of Pu, the first moment, and the second moment of the spontaneous fission neutron multiplicity distribution are all intrinsic properties of the nuclide 240 Pu, which are fixed values, being 475.276 fission / (g•s), 2.156, and 3.825 respectively.

[0215] First, taking the plutonium concentration and the mass ratio of plutonium isotopes in a typical pressurized water reactor spent fuel assembly as an example, a three-dimensional Monte Carlo program is used to establish a three-dimensional calculation model of a plutonium solution sphere with R = 10 cm. At the same time, assuming that the neutron coincidence gate duration t g = 64 microseconds (μs), the overall parameters of the system are calculated. Among them, the leakage multiplication factor (i.e., the first type of multiplication leakage factor ), the leakage multiplication factor (i.e., the second type of multiplication leakage factor ) are respectively the ratios of the number of neutrons leaked after multiplication of spontaneous fission source neutrons and source neutrons to the number of source neutrons. The net multiplication factor , the net multiplication factor are respectively the ratios of the number of neutrons generated after multiplication of spontaneous fission source neutrons and source neutrons to the number of source neutrons. The detection efficiency (i.e., the first type of detection efficiency ), (i.e., the second type of detection efficiency ) are estimated using the reaction rate of 3 He in the detector. The gate utilization factor n, p is defined as the ratio of the coincidence counts when the gate durations are t and ∞ respectively. The first moment g of the induced fission neutron multiplicity distribution when there is only a spontaneous fission source in the statistical system (i.e., the second type of first moment ) and the second moment (i.e., the second type of second moment ) are calculated. At the same time, the total neutron count rate and the coincidence neutron count rate can be statistically obtained. The Monte Carlo statistical methods for the above overall parameters are basically common knowledge in the art or existing technologies.

[0216] The calculation of the spatial correction factor mainly includes: , , (i.e., step S110, obtaining the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor ). The solution sphere with R = 10 cm is stratified, with each layer being 1 cm, that is, takes a value of 10. Spontaneous fission neutron sources are set layer by layer to form multiple calculation models, and the shares of induced fission reaction rates caused by the initial source neutrons in sub-region are respectively counted (i.e., the first induced fission reaction rate share ), and the net multiplication coefficients of the initial source neutrons in sub-region (i.e., the first net multiplication coefficient ). Neutron sources are set layer by layer to form multiple calculation models, and the shares of induced fission reaction rates (i.e., the second induced fission reaction rate share ) caused by the initial source neutrons in sub-region in sub-region are respectively counted, and the net multiplication coefficients of the initial source neutrons in sub-region (i.e., the second net multiplication coefficient ). The energy spectrum of induced fission neutrons is set layer by layer, and the multiplication leakage coefficients of induced fission neutrons in sub-region (i.e., the second multiplication leakage coefficient ), and the detection efficiencies of induced fission neutrons in sub-region (i.e., the second detection efficiency ) are calculated and statistically analyzed. The spatial correction factor of induced fission neutrons is calculated according to formula (8) in step S110.

[0217] The spatial effect correction factor of spontaneous fission neutrons is calculated as follows: The neutron detection efficiencies in sub-region (i.e., the first detection efficiency ) and the multiplication leakage coefficients (i.e., the first multiplication leakage coefficient ) of spontaneous fission neutrons, which are statistically analyzed using the calculation model with spontaneous fission neutron sources set layer by layer, are used to calculate the spatial correction factor of spontaneous fission neutrons according to formula (1) in step S110.

[0218] For models with R = 15 cm, 20 cm, 25 cm, and 30 cm, modeling and analysis are carried out in the same way, and the corresponding overall parameters and spatial effect correction factors are statistically obtained. The calculation results of these characteristic parameters are shown in Table 1.

[0219] Table 1

[0220]

[0221] It should be noted that the values in Table 1 are only for illustration and are not used to limit this application.

[0222] Finally, based on the total neutron count rate simulated by the three-dimensional Monte Carlo program and the coincidence neutron count rate , as well as the statistically obtained overall parameters and the spatial effect correction factors of spontaneous fission neutrons and induced fission neutrons, combined with the plutonium isotope mass ratio, taking the above information as input, the method in step S120 of this embodiment of the application can be used to calculate , and the corresponding results are shown in Table 2. Among them, Table 2 is the true value and the improved model and the spatial model. The comparison of the results calculated by these two models. The g in Table 2 represents the mass unit gram. It can be seen from Table 2 that the method provided by this embodiment of the application shows very good estimation accuracy. Especially as the radius of the plutonium solution sphere increases, the advantages of the spatial model equations are more obvious.

[0223] Table 2

[0224]

[0225] According to the value calculated above, as well as the known plutonium isotope composition ratio and the volume of the solution equipment, the plutonium inventory information can be further solved according to formula (9) in step S130.

[0226] This embodiment of the application has at least the following beneficial effects:

[0227] 1. Based on the "point model" equations and their improved versions, considering the differences between the initial source distribution and the induced fission source distribution, spatial effect corrections for induced fission neutron multiplication leakage and neutron net multiplication are carried out, and at the same time, spontaneous fission neutrons and Due to the differences in neutrons in terms of detection efficiency, multiplication leakage, etc., a set of spatial model equations considering spatial effects and applicable to solution systems is finally obtained. After considering the spatial effects, it can more accurately reflect the measurement results of the neutron count rate of the external monitoring system of a large-volume plutonium solution system, and further more accurately estimate the plutonium inventory in the system. This method takes into account the characteristics of the induced fission neutron source varying with space, solves the spatial effects of induced fission neutron multiplication leakage and neutron net multiplication in a large-volume solution system, and realizes the neutron passive non-destructive monitoring and analysis of the plutonium content in a large-volume solution system. It is an advanced and engineering-feasible method for monitoring the plutonium content in solution systems.

[0228] 2. Effectively solves the spatial effect problems of net multiplication and multiplication leakage coefficient in the plutonium content monitoring method for large-volume solution systems, and introduces the first spatial effect correction factor , to consider the volume weighting of the power value of the spontaneous fission neutron multiplication leakage coefficient, and introduces the second spatial effect correction factor and the third spatial effect correction factor , to consider the distribution of induced fission reaction rate and the weighting of the initial source distribution, and at the same time consider the spatial distribution of detection efficiency and the difference in neutron energy spectra between the initial source and the induced fission source, so that the plutonium content monitoring based on the spatial model equations can well predict the neutron count rate of a large-volume solution system, thus being applicable to the calculation of the plutonium content in a large-volume solution system and solving the problem of uneven spatial distribution of the multiplication leakage coefficient. Example 2

[0229] The critical safety assessment method provided by the embodiments of this application is also executed by a critical safety assessment system, an electronic device, etc. Here, an example will be given with the critical safety assessment method being executed by an electronic device.

[0230] The critical safety assessment method provided by the embodiments of this application can be applied to the post-treatment process of spent fuel.

[0231] It should be noted that the critical safety assessment method provided by the embodiments of this application can be applied to plutonium-containing solution systems, especially large-volume solution systems.

[0232] The critical safety assessment method provided by the embodiments of this application may include steps S210 to S220.

[0233] S210. Determine the plutonium concentration of the solution system according to the plutonium inventory neutron monitoring method of Example 1.

[0234] For the specific implementation manner of step S210, please refer to Example 1 and will not be elaborated here.

[0235] S220. Evaluate the critical safety of the solution system using the plutonium concentration.

[0236] In some embodiments, when the plutonium concentration is less than or equal to the plutonium concentration threshold, the critical safety of the solution system is determined to be in a safe state; or, when the plutonium concentration is greater than the plutonium concentration threshold, the critical safety of the solution system is determined to be in an unsafe state, and an alarm message is output, which is used to indicate that the critical safety of the solution system is in an unsafe state.

[0237] It should be noted that the plutonium concentration threshold can be set according to the actual situation and is not limited herein. For example, the value range of the plutonium concentration threshold can be from 1 g / L to 10 g / L. Embodiment 3

[0238] The embodiment of the present application further provides a plutonium inventory neutron monitoring device, which can be applied to a plutonium-containing solution system. The device includes:

[0239] A first acquisition module, configured to acquire a first space effect correction factor 、a second space effect correction factor and a third space effect correction factor , where the first space effect correction factor is the space effect correction factor of the spontaneous fission neutron multiplication leakage coefficient, the second space effect correction factor is the space effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the spontaneous fission neutron source, and the third space effect correction factor is the space effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the neutron source;

[0240] A first determination module, connected to the first acquisition module, is configured to determine the equivalent mass of plutonium-240 、based on the first space effect correction factor 、the second space effect correction factor ; ;

[0241] A second determination module, connected to the first determination module, is configured to determine the plutonium concentration of the solution system according to the equivalent mass ;

[0242] In some embodiments, the solution system includes sub-regions, where

[0243] is a positive integer;

[0244] The first acquisition module is specifically configured to: acquire the first type of multiplication leakage coefficient and the first type of detection efficiency of the solution system, and the a first detection efficiency and a volume, the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the first multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the sub-region only, the first detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the sub-region only, the first multiplication leakage coefficient, the first detection efficiency and the volume respectively correspond to the sub-regions one by one;

[0245] According to the first type of multiplication leakage coefficient, the first type of detection efficiency, a first multiplication leakage coefficient, a first detection efficiency and a volume, determine the first space effect correction factor .

[0246] In some embodiments, the solution system includes sub-regions, where is a positive integer;

[0247] The first acquisition module is specifically used for:

[0248] Acquire the first type of multiplication leakage coefficient and the first type of detection efficiency of the solution system, and the volumes, the first induced fission reaction rate fractions, the first net multiplication coefficients, the second multiplication leakage coefficients, and the second detection efficiencies of the sub-regions; the first type of multiplication leakage coefficient is the multiplication leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the first induced fission reaction rate fraction is the fraction of the induced fission reaction rate caused by the spontaneous fission neutron source of the sub-region in the sub-region , the first net multiplication coefficient is the net multiplication coefficient of the spontaneous fission neutron source of the sub-region , the second multiplication leakage coefficient is the multiplication leakage coefficient of the induced fission neutrons of the sub-region , the second detection efficiency is the detection efficiency of the induced fission neutrons of the sub-region , the volume, the first net multiplication coefficient, the second multiplication leakage coefficient and the second detection efficiency respectively correspond to the sub-regions one by one, and one sub-region corresponds to a first induced fission reaction rate fraction, and are both positive integers;

[0249] Determine the second spatial effect correction factor based on the first type of breeding leakage coefficient, the first type of detection efficiency, each volume, each first induced fission reaction rate fraction, each first net breeding coefficient, each second breeding leakage coefficient, and each second detection efficiency. .

[0250] In some embodiments, the solution system includes sub-regions, where is a positive integer;

[0251] The first acquisition module is specifically configured to:

[0252] Acquire the first type of breeding leakage coefficient and the first type of detection efficiency of the solution system, and each volume of the sub-regions, each second induced fission reaction rate fraction, each second net breeding coefficient, each second breeding leakage coefficient, and each second detection efficiency; the first type of breeding leakage coefficient is the breeding leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, the second induced fission reaction rate fraction is the of the neutron source in the sub-region causing the induced fission reaction rate fraction, the second net breeding coefficient is the of the neutron source in the sub-region net breeding coefficient, the second breeding leakage coefficient is the breeding leakage coefficient of the induced fission neutrons in the sub-region the second detection efficiency is the detection efficiency of the induced fission neutrons in the sub-region each second induced fission reaction rate fraction, and are both positive integers;

[0253] Determine the third spatial effect correction factor based on the first type of breeding leakage coefficient, the first type of detection efficiency, each volume, each second induced fission reaction rate fraction, each second net breeding coefficient, each second breeding leakage coefficient, and each second detection efficiency. .

[0254] In some examples, the plutonium inventory neutron monitoring device provided by the embodiments of the present application may include a plurality of neutron monitoring channels and a data analysis workstation surrounding the solution system. Among them, the neutron monitoring channel includes a neutron detector and corresponding moderators, shields, electronics components, and display modules; the signals of the neutron monitoring channels are transmitted to the data analysis workstation through a data acquisition module, and the data analysis workstation analyzes and processes the data using the method of Embodiment 1.

[0255] The plutonium inventory neutron monitoring device provided by the embodiments of the present application can be used to execute the plutonium inventory neutron monitoring method, that is, it has the beneficial effects and implementation manners of the plutonium inventory neutron monitoring method provided by Embodiment 1 of the present application. Specifically, reference can be made to the specific description of the plutonium inventory neutron monitoring method in the above Embodiment 1, and this embodiment will not be elaborated here. Embodiment 4

[0256] The embodiments of the present application further provide a critical safety assessment system, which can be applied to a plutonium-containing solution system. The critical safety assessment system includes: the plutonium inventory neutron monitoring device in Embodiment 3, which is used to determine the plutonium concentration of the solution system; an assessment device, connected to the plutonium inventory neutron monitoring device, which is used to evaluate the critical safety of the solution system using the plutonium concentration.

[0257] The critical safety assessment system provided by the embodiments of the present application can be used to execute the critical safety assessment method, that is, it has the beneficial effects and implementation manners of the critical safety assessment method provided by Embodiment 2 of the present application. Specifically, reference can be made to the specific description of the critical safety assessment method in the above Embodiment 2, and this embodiment will not be elaborated here.

[0258] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present application. However, the present application is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present application, and these modifications and improvements are also regarded as the protection scope of the present application.

Claims

1. A method for monitoring plutonium inventory neutrons, characterized in that: Applied to a solution system containing plutonium, the method comprises: Get the first space effect correction factor , Second space effect correction factor and the third space effect correction factor , wherein the first spatial effect correction factor is the spatial effect correction factor of the spontaneous fission neutron multiplication leakage coefficient, the second spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the spontaneous fission neutron source, and the third spatial effect correction factor for The spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the neutron source; According to the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor , determine the equivalent mass of plutonium-240 ; According to the equivalent mass , determining the plutonium concentration of the solution system; The solution system comprises Sub-districts, is a positive integer; Get the first space effect correction factor , specifically including: obtaining a first-type proliferation leakage coefficient and a first-type detection efficiency of the solution system, and Sub-district The first proliferation leakage coefficient, The first detection efficiency and a volume, the first type of proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of neutron leakage from the solution system when there is only a spontaneous fission neutron source in the solution system, the first proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the sub-area, the first detection efficiency is the detection efficiency of neutron leakage from the solution system when there is only a spontaneous fission neutron source in the sub-area, and the first proliferation leakage coefficient, the first detection efficiency and the volume correspond to the sub-areas one by one respectively; According to the first type of proliferation leakage coefficient, the first type of detection efficiency, The first proliferation leakage coefficient, The first detection efficiency and volume, determine the first spatial effect correction factor .

2. The method according to claim 1, characterized in that According to the first type of proliferation leakage coefficient, the first type of detection efficiency, The first proliferation leakage coefficient, The first detection efficiency and volume, determine the first spatial effect correction factor , specifically including: The first-type proliferation leakage coefficient, the first-type detection efficiency, The first proliferation leakage coefficient, The first detection efficiency and Substitute the volume into formula (1) to calculate and obtain the first space effect correction factor ; The formula (1) includes: （1） in, Indicates The first detection efficiency of each sub-area; Indicates The first proliferation leakage coefficient of each sub-area; Indicates The volume of each sub-region; represents the total volume of the solution system, i.e. The sum of the volumes; represents the first type of detection efficiency; represents the first type proliferation leakage coefficient.

3. The method according to claim 1, characterized in that The solution system comprises Sub-districts, is a positive integer; Get the second space effect correction factor , specifically including: obtaining a first-type proliferation leakage coefficient and a first-type detection efficiency of the solution system, and Sub-district Volume, The first induced fission reaction rate share, The first net growth coefficient, The second proliferation leakage coefficient, and The first type of proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, and the first induced fission reaction rate share is the sub-area The spontaneous fission neutron source is in the sub-region The induced fission reaction rate share caused by the first net proliferation coefficient is the sub-area The net multiplication coefficient of the spontaneous fission neutron source, the second multiplication leakage coefficient is The multiplication leakage coefficient of induced fission neutrons, the second detection efficiency is The detection efficiency of induced fission neutrons, the volume, the first net proliferation coefficient, the second proliferation leakage coefficient and the second detection efficiency correspond to sub-areas one by one, and one sub-area corresponds to The first induced fission reaction rate fraction, and All are positive integers; According to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The first induced fission reaction rate share, The first net growth coefficient, The second proliferation leakage coefficient, and The second detection efficiency determines the second spatial effect correction factor .

4. The method according to claim 3, characterized in that According to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The first induced fission reaction rate share, The first net growth factor, The second proliferation leakage coefficient, and The second detection efficiency determines the second spatial effect correction factor , specifically including: The first-type proliferation leakage coefficient, the first-type detection efficiency, Volume, The first induced fission reaction rate share, The first net growth coefficient, The second proliferation leakage coefficient, and Substitute the second detection efficiency into formula (2) and calculate the second spatial effect correction factor ; The formula (2) includes: （2） in, Indicates The volume of each sub-region; represents the total volume of the solution system, i.e. The sum of the volumes; represents the first type of detection efficiency; represents the first type proliferation leakage coefficient; represents the first induced fission reaction rate fraction; represents the second detection efficiency; represents the second proliferation leakage coefficient; Represents the first net growth factor.

5. The method according to claim 1, characterized in that The solution system comprises Sub-districts, is a positive integer; Get the third space effect correction factor , specifically including: obtaining a first-type proliferation leakage coefficient and a first-type detection efficiency of the solution system, and Sub-district Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and The first type of proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, and the second induced fission reaction rate share is the sub-area of Neutron source in sub-area The second net proliferation coefficient is the fraction of the induced fission reaction rate caused by of The net multiplication coefficient of the neutron source, the second multiplication leakage coefficient is The multiplication leakage coefficient of induced fission neutrons, the second detection efficiency is The detection efficiency of induced fission neutrons, the volume, the second net proliferation coefficient, the second proliferation leakage coefficient and the second detection efficiency correspond to sub-areas one by one, and one sub-area corresponds to The second induced fission reaction rate fraction, and All are positive integers; According to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and The second detection efficiency determines the third spatial effect correction factor .

6. The method according to claim 5, characterized in that According to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and The second detection efficiency determines the third spatial effect correction factor , specifically including: The first-type proliferation leakage coefficient, the first-type detection efficiency, Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and Substitute the second detection efficiency into formula (3) and calculate the third spatial effect correction factor ; The formula (3) includes: （3） in, Indicates The volume of each sub-region; represents the total volume of the solution system, i.e. The sum of the volumes; represents the first type of detection efficiency; represents the first type proliferation leakage coefficient; represents the second induced fission reaction rate fraction; represents the second detection efficiency; represents the second proliferation leakage coefficient; Represents the second net growth factor.

7. The method according to claim 1, characterized in that According to the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor , determine the equivalent mass of plutonium-240 , specifically including: Acquire first information of the solution system, wherein the first information includes a total neutron count rate , consistent with the neutron counting rate , spontaneous fission rate of plutonium-240 , the first type of detection efficiency , the second type of detection efficiency , the first type of proliferation leakage coefficient , the second type of proliferation leakage coefficient , first-order moment of the first kind , the first kind of second order moment , the second first-order moment , the second moment of the second kind AND gate utilization factor ; Wherein, the first type of detection efficiency is the detection efficiency of leaked neutrons when the solution system has only spontaneous fission neutron sources; the second type of detection efficiency For the solution system only Detection efficiency of leaked neutrons in neutron source; first-class multiplication leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system; the second type proliferation leakage coefficient For the solution system only When the neutron source is used, the proliferation leakage coefficient of the solution system; the first-order moment is the first-order moment of the spontaneous fission neutron multiplicity distribution in the solution system; the first-order second-order moment is the second-order moment of the spontaneous fission neutron multiplicity distribution in the solution system; the second first-order moment is the first-order moment of the multiplicity distribution of induced fission neutrons in the solution system; the second-order moment of the second kind is the second-order moment of the multiplicity distribution of induced fission neutrons in the solution system; According to the first information, the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor , determine the equivalent mass of plutonium-240 .

8. The method according to claim 7, characterized in that According to the first information, the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor , determine the equivalent mass of plutonium-240 , specifically including: The first information, the first spatial effect correction factor , the second spatial effect correction factor and the third spatial effect correction factor Substituting into formula (4), the equivalent mass of plutonium-240 is calculated ; The formula (4) includes: （4）。 9. The method according to claim 8, characterized in that The formula (4) is obtained from the space model equation group, and the space model equation group includes formula (5) and formula (6). The formula (5) includes: （5） in, express The ratio of the number of neutrons to the number of spontaneous fission neutrons; The formula (6) includes: （6）。 10. The method according to claim 1, characterized in that According to the equivalent mass , determining the plutonium concentration of the solution system, specifically comprising: Obtaining the first mass percentage of plutonium-238 , the second mass percentage of plutonium-240 , the third mass percentage of plutonium-242 ; Equivalent mass , first mass percentage , the second mass percentage and the third mass percentage Substituting into formula (7), the total mass of plutonium in the solution system is calculated as ; The formula (7) includes: （7） According to the total mass of plutonium , determine the plutonium concentration of the solution system.

11. A criticality safety assessment method, characterized in that: Applied to a solution system containing plutonium, the method comprises: The method for neutron monitoring of plutonium inventory according to any one of claims 1 to 10, determining the plutonium concentration of the solution system; The plutonium concentration is used to evaluate the criticality safety of the solution system.

12. A plutonium inventory neutron monitoring device, characterized in that: Applicable to a solution system containing plutonium, the device comprises: The first acquisition module is used to obtain the first spatial effect correction factor , Second space effect correction factor and the third space effect correction factor , wherein the first spatial effect correction factor is the spatial effect correction factor of the spontaneous fission neutron multiplication leakage coefficient, the second spatial effect correction factor is the spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the spontaneous fission neutron source, and the third spatial effect correction factor for The spatial effect correction factor of the induced fission neutron multiplication leakage coefficient caused by the neutron source; A first determining module is connected to the first acquiring module and is used to correct the first spatial effect factor , the second spatial effect correction factor and the third spatial effect correction factor , determine the equivalent mass of plutonium-240 ; A second determining module is connected to the first determining module and is used to determine the equivalent mass , determining the plutonium concentration of the solution system; The solution system comprises Sub-districts, is a positive integer; The first acquisition module is specifically used to: obtaining a first-type proliferation leakage coefficient and a first-type detection efficiency of the solution system, and Sub-district The first proliferation leakage coefficient, The first detection efficiency and a volume, the first type of proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of neutron leakage from the solution system when there is only a spontaneous fission neutron source in the solution system, the first proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the sub-area, the first detection efficiency is the detection efficiency of neutron leakage from the solution system when there is only a spontaneous fission neutron source in the sub-area, and the first proliferation leakage coefficient, the first detection efficiency and the volume correspond to the sub-areas one by one respectively; According to the first type of proliferation leakage coefficient, the first type of detection efficiency, The first proliferation leakage coefficient, The first detection efficiency and volume, determine the first spatial effect correction factor .

13. The device according to claim 12, characterized in that The solution system comprises Sub-districts, is a positive integer; The first acquisition module is specifically used to: obtaining a first-type proliferation leakage coefficient and a first-type detection efficiency of the solution system, and Sub-district Volume, The first induced fission reaction rate share, The first net growth coefficient, The second proliferation leakage coefficient, and The first type of proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, and the first induced fission reaction rate share is the sub-area The spontaneous fission neutron source is in the sub-region The induced fission reaction rate share caused by the first net proliferation coefficient is the sub-area The net multiplication coefficient of the spontaneous fission neutron source, the second multiplication leakage coefficient is The multiplication leakage coefficient of induced fission neutrons, the second detection efficiency is The detection efficiency of induced fission neutrons, the volume, the first net proliferation coefficient, the second proliferation leakage coefficient and the second detection efficiency correspond to sub-areas one by one, and one sub-area corresponds to The first induced fission reaction rate fraction, and All are positive integers; According to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The first induced fission reaction rate share, The first net growth coefficient, The second proliferation leakage coefficient, and The second detection efficiency determines the second spatial effect correction factor ; and / or, The solution system comprises Sub-districts, is a positive integer; The first acquisition module is specifically used to: obtaining a first-type proliferation leakage coefficient and a first-type detection efficiency of the solution system, and Sub-district Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and The first type of proliferation leakage coefficient is the proliferation leakage coefficient of the solution system when there is only a spontaneous fission neutron source in the solution system, the first type of detection efficiency is the detection efficiency of the leakage neutrons of the solution system when there is only a spontaneous fission neutron source in the solution system, and the second induced fission reaction rate share is the sub-area of Neutron source in sub-area The second net proliferation coefficient is the fraction of the induced fission reaction rate caused by of The net multiplication coefficient of the neutron source, the second multiplication leakage coefficient is The multiplication leakage coefficient of induced fission neutrons, the second detection efficiency is The detection efficiency of induced fission neutrons, the volume, the second net proliferation coefficient, the second proliferation leakage coefficient and the second detection efficiency correspond to sub-areas one by one, and one sub-area corresponds to The second induced fission reaction rate fraction, and All are positive integers; According to the first type of proliferation leakage coefficient, the first type of detection efficiency, Volume, The second induced fission reaction rate fraction, The second net growth factor, The second proliferation leakage coefficient, and The second detection efficiency determines the third spatial effect correction factor .

14. A criticality safety assessment system, characterized in that: Applied to a solution system containing plutonium, the criticality safety assessment system comprises: The plutonium inventory neutron monitoring device according to claim 12 or 13, used to determine the plutonium concentration of a solution system; An evaluation device is connected to the plutonium inventory neutron monitoring device and is used to evaluate the criticality safety of the solution system using the plutonium concentration.

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