Nuclear power plant fuel operation accident source item result determination method and device, nuclear power plant fuel operation accident alarm method and nuclear power plant fuel operation accident alarm system

Abstract

The invention discloses a nuclear power plant fuel operation accident source item result determination method and device and a nuclear power plant fuel operation accident alarm method and system, and relates to the technical field of nuclear industry. The method for determining the fuel operation accident source item result of the nuclear power plant comprises the following steps: acquiring a target decontamination factor corresponding to a target nuclide in a first time period and the total concentration of aerosol iodine retained in a spent pool of the nuclear power plant in a second time period; determining a first release amount corresponding to the target nuclide in the first time period according to the target decontamination factor; according to the total concentration of iodine in the aerosol, determining the share of iodine volatilized in the form of elements in the spent fuel pool in the second time period; determining a second release amount of the element iodine in a second time period according to the iodine share; and generating a fuel operation accident source item result of the nuclear power plant according to the first release amount and the second release amount. According to the embodiment of the invention, the method can improve the accuracy of determining the fuel operation accident source item result of the nuclear power plant.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nuclear industry, and particularly relates to a fuel handling accident source term result determination and device for a nuclear power plant, and a fuel handling accident alarm method and system for the nuclear power plant. BACKGROUND

[0002] For a fuel handling accident occurring in a fuel building, a conventional fuel handling accident source term calculation assumes that radioactive substances escaping from a fuel pool to the fuel building are released to the environment within 2 hours, and conservatively assumes that aerosol iodine is completely dissolved in the spent fuel pool, and when the pH value of the pool water is low, the aerosol iodine entering the pool water is instantaneously converted into elemental iodine. However, in reality, due to reasons such as the aerosol iodine not being completely dissolved in the spent fuel pool, the accuracy of the fuel handling accident source term result determined in the related art needs to be improved. SUMMARY

[0003] The technical problem to be solved by the application is to solve the above-mentioned deficiencies existing in the prior art, and provide a fuel handling accident source term result determination and device for a nuclear power plant, and a fuel handling accident alarm method and system for the nuclear power plant. The method can improve the accuracy of the fuel handling accident source term result determination for the nuclear power plant by comprehensively considering the influence of the target decontamination factor, the aerosol iodine concentration, and the iodine fraction in the elemental form re-volatilized in the spent fuel pool in the second period on the fuel handling accident source term of the nuclear power plant.

[0004] In a first aspect, an embodiment of the application provides a fuel handling accident source term result determination method for a nuclear power plant, comprising:

[0005] obtaining a target decontamination factor corresponding to a target nuclide in a first period, and a total concentration of aerosol iodine remaining in a spent fuel pool of the nuclear power plant in a second period; the target nuclide includes at least one of a radioactive isotope of inert gas, elemental iodine, and organic iodine; the first period includes a time when a fuel handling accident of the nuclear power plant occurs to N hours after the occurrence; the second period includes N hours to M hours after the occurrence of the fuel handling accident, and M is greater than N;

[0006] determining a first release amount of the target nuclide in the first period according to the target decontamination factor;

[0007] determining an iodine fraction in the elemental form re-volatilized in the spent fuel pool in the second period according to the total concentration of the aerosol iodine;

[0008] determining a second release amount of the elemental iodine in the second period according to the iodine fraction;

[0009] generating a fuel handling accident source term result of the nuclear power plant according to the first release amount and the second release amount.

[0010] In some embodiments of the first aspect, the target nuclide includes elemental iodine,

[0011] obtaining a target decontamination factor corresponding to the target nuclide in the first period, specifically comprising:

[0012] obtaining the rising time of the radioactive gas bubble and the diameter of the radioactive gas bubble;

[0013] determining the target decontamination factor corresponding to the element iodine in the first period according to the rising time of the bubble and the diameter of the bubble.

[0014] In some embodiments of the first aspect, the rising time of the radioactive gas bubble and the diameter of the radioactive gas bubble are obtained, specifically comprising:

[0015] obtaining the internal pressure of the fuel rod;

[0016] determining the rising time of the radioactive gas bubble according to the internal pressure of the fuel rod and formula (1);

[0017] formula (1) comprises:

[0018]

[0019] wherein t is the rising time of the bubble; x is the internal pressure of the fuel rod;

[0020] determining the diameter of the radioactive gas bubble according to the internal pressure of the fuel rod and formula (2);

[0021] formula (2) comprises:

[0022] d = -0.0002x + 1.0009 (2)

[0023] wherein d is the diameter of the bubble.

[0024] In some embodiments of the first aspect, the target decontamination factor corresponding to the element iodine in the first period is determined according to the rising time of the bubble and the diameter of the bubble, specifically comprising:

[0025] substituting the rising time of the bubble and the diameter of the bubble into formula (3) to obtain the target decontamination factor corresponding to the element iodine in the first period;

[0026] formula (3) comprises:

[0027] DF I = 81.046e 0.305(t / d) (3)

[0028] wherein t is the rising time of the bubble; d is the diameter of the bubble; DF I is the target decontamination factor corresponding to the element iodine in the first period.

[0029] In some embodiments of the first aspect, in the case that the target nuclide includes a radioactive isotope of noble gas and organic iodine, the target decontamination factors corresponding to the radioactive isotope of noble gas and the organic iodine are both 1.

[0030] In some embodiments of the first aspect, the total concentration of aerosol iodine remaining in the spent pool of the nuclear power plant in the second period of time is specifically obtained by:

[0031] obtaining the sum of the molar numbers of the iodine isotopes released from the gap of the damaged fuel assembly in the nuclear power plant;

[0032] determining the total concentration of aerosol iodine remaining in the spent pool of the nuclear power plant in the second period of time according to the sum of the molar numbers.

[0033] In some embodiments of the first aspect, the sum of the molar numbers of the iodine isotopes released from the gap of the damaged fuel assembly in the nuclear power plant is specifically obtained by:

[0034] obtaining the decay constant of iodine, the Avogadro constant, and the iodine activity released from the gap of the damaged fuel assembly in the nuclear power plant;

[0035] determining the sum of the molar numbers of the iodine isotopes released from the gap of the damaged fuel assembly in the nuclear power plant according to the decay constant, the Avogadro constant, and the iodine activity.

[0036] In some embodiments of the first aspect, the sum of the molar numbers of the iodine isotopes released from the gap of the damaged fuel assembly in the nuclear power plant is specifically determined according to the decay constant, the Avogadro constant, and the iodine activity by:

[0037] substituting the decay constant, the Avogadro constant, and the iodine activity into formula (4) to obtain the sum of the molar numbers of the iodine isotopes released from the gap of the damaged fuel assembly in the nuclear power plant;

[0038] Formula (4) includes:

[0039]

[0040] wherein N I，gap is the sum of the molar numbers; A(I i ) is the iodine activity; I i is the isotope of iodine; is the decay constant; N A is the Avogadro constant.

[0041] In some embodiments of the first aspect, the total concentration of aerosol iodine remaining in the spent pool of the nuclear power plant in the second period of time is specifically determined according to the sum of the molar numbers by:

[0042] obtaining the free volume of the spent pool;

[0043] Substituting the sum of free volume and number of moles into formula (5), the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is calculated.

[0044] Formula (5) includes:

[0045]

[0046] Among them, C t This represents the total concentration of iodine in aerosols; N I，gap It is the sum of the number of moles; V pool For free volume.

[0047] In some embodiments of the first aspect, the fraction of iodine that re-volatilizes in elemental form in the waste tank during the second time period is determined based on the total concentration of aerosol iodine, specifically including:

[0048] Obtain the concentration ratio of elemental iodine to iodide ions in the waste pool;

[0049] The partition coefficient of iodine in aerosols is determined based on the total concentration and concentration ratio of iodine in aerosols.

[0050] Based on the allocation coefficient and the total concentration of aerosol iodine, the proportion of iodine that re-volatilizes in elemental form in the waste tank during the second time period is determined.

[0051] In some embodiments of the first aspect, obtaining the concentration ratio of elemental iodine to iodide ions in the wastewater specifically includes:

[0052] Obtain the hydrogen ion concentration in the wastewater;

[0053] Substituting the hydrogen ion concentration into formula (6), the concentration ratio of iodine element to the square of iodide ions in the waste pool is calculated.

[0054] Formula (6) includes:

[0055] R i =[I2] / [I - ] 2 =C h 2 / (6.05×10 -14 +1.47×10 -9 C h (6)

[0056] Among them, R i For concentration ratio; C h This represents the hydrogen ion concentration.

[0057] In some embodiments of the first aspect, the partition coefficient of iodine in the aerosol is determined based on the total concentration and concentration ratio of iodine in the aerosol, specifically including:

[0058] Substitute the total concentration and concentration ratio of iodine in the aerosol into formula (7) to calculate the distribution coefficient of iodine in the aerosol.

[0059] Formula (7) includes:

[0060] B m =4C t +1 / R i (7)

[0061] Among them, R i For concentration ratio; C t B represents the total concentration of iodine in aerosols. m This is the allocation coefficient.

[0062] In some embodiments of the first aspect, the fraction of iodine re-volatilized in elemental form in the waste tank during the second time period is determined based on the distribution coefficient and the total concentration of aerosol iodine, specifically for:

[0063] Substituting the distribution coefficient and the total concentration of aerosol iodine into formula (8), the proportion of iodine that is volatilized again in elemental form in the waste pool during the second time period is calculated.

[0064] Formula (8) includes:

[0065]

[0066] Among them, B m C is the allocation coefficient; t X represents the total concentration of iodine in aerosols. e This refers to the iodine content.

[0067] In some embodiments of the first aspect, the second release amount of elemental iodine during the second time period is determined based on the iodine fraction, specifically including:

[0068] The rate of elemental iodine release from the spent pool during the second time period was determined based on the iodine fraction.

[0069] The second release amount of elemental iodine in the second time period was determined based on the elemental iodine rate.

[0070] In some embodiments of the first aspect, the rate of elemental iodine release from the spent pool during the second time period is determined based on the iodine fraction, specifically including:

[0071] Obtain the mass transfer coefficient, surface area of ​​the waste pool, and free volume;

[0072] The rate at which elemental iodine is released from the waste pool during the second time period is determined based on the mass transfer coefficient, surface area, free volume, and iodine fraction.

[0073] In some embodiments of the first aspect, the rate of elemental iodine release from the waste pool during the second time period is determined based on the mass transfer coefficient, surface area, and free volume, specifically including:

[0074] The rate at which elemental iodine is released from the waste pool during the second time period is calculated by substituting the mass transfer coefficient, surface area, and free volume into formula (9).

[0075] Formula (9) includes:

[0076] λ e =K L X e S pool / V pool (9)

[0077] Where, λ e For the rate of elemental iodine; K L X is the mass transfer coefficient; e For iodine fraction; S pool V is the surface area; pool For free volume.

[0078] Based on the same inventive concept, in a second aspect, embodiments of this application also provide a fuel operation accident alarm method for a nuclear power plant, comprising:

[0079] Based on the method for determining the source term results of fuel operation accidents in nuclear power plants according to any one of the first aspects, generate the source term results of fuel operation accidents in nuclear power plants.

[0080] The accident consequence assessment model was used to process the source term results of the fuel operation accident to obtain the radioactive dose distribution corresponding to the source term results of the fuel operation accident.

[0081] If the radiation dose distribution is greater than or equal to a preset threshold, an alarm message is output. The alarm message is used to indicate that the radiation dose distribution is greater than or equal to the preset threshold.

[0082] Based on the same inventive concept, in a third aspect, embodiments of this application also provide a device for determining the source term results of a fuel operation accident in a nuclear power plant, comprising:

[0083] The first acquisition module is used to acquire the target decontamination factor corresponding to the target nuclide in the first time period, and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period; the target nuclide includes at least one of radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes the period from the time of the fuel operation accident at the nuclear power plant to the Nth hour after the accident; the second time period includes the period from the Nth hour to the Mth hour after the fuel operation accident, where M is greater than N;

[0084] The first determining module, connected to the first acquiring module, is used to determine the first release amount of the target nuclide in the first time period based on the target decontamination factor.

[0085] The second determining module, connected to the first determining module, is used to determine the proportion of iodine that is re-volatile in elemental form in the waste pool during the second time period based on the total concentration of aerosol iodine.

[0086] The third determining module, connected to the second determining module, is used to determine the second release amount of elemental iodine in the second time period based on the iodine fraction.

[0087] The generation module, connected to the first determination module and the third determination module, is used to generate the fuel operation accident source item results of the nuclear power plant based on the first release amount and the second release amount.

[0088] In some embodiments of the third aspect, the target nuclide includes elemental iodine.

[0089] The first acquisition module is specifically used for:

[0090] Obtain the rise time and diameter of the radioactive bubble;

[0091] Based on the bubble rise time and bubble diameter, the target decontamination factor corresponding to elemental iodine in the first time period is determined.

[0092] In some embodiments of the third aspect, the first acquisition module is specifically used for:

[0093] Obtain the sum of the molar numbers of each iodine isotope released from the gaps in damaged fuel assemblies in a nuclear power plant;

[0094] The total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is determined based on the sum of the molar numbers.

[0095] In some embodiments of the third aspect, the second determining module is specifically used for:

[0096] Obtain the concentration ratio of elemental iodine to iodide ions in the waste pool;

[0097] The partition coefficient of iodine in aerosols is determined based on the total concentration and concentration ratio of iodine in aerosols.

[0098] Based on the allocation coefficient and the total concentration of aerosol iodine, the proportion of iodine that re-volatilizes in elemental form in the waste tank during the second time period is determined.

[0099] Fourthly, embodiments of this application also provide a fuel operation accident alarm system for a nuclear power plant, comprising:

[0100] The third aspect is a nuclear power plant fuel operation accident source term result determination device, used to generate nuclear power plant fuel operation accident source term results;

[0101] The processing device, connected to the fuel operation accident source term result determination device of the nuclear power plant, is used to process the fuel operation accident source term results using an accident consequence assessment model to obtain the radioactive dose distribution corresponding to the fuel operation accident source term results.

[0102] The output device, connected to the processing device, is used to output alarm information when the radioactive dose distribution is greater than or equal to a preset threshold. The alarm information is used to indicate that the radioactive dose distribution is greater than or equal to the preset threshold.

[0103] According to the method and apparatus for determining the source term of a nuclear power plant fuel operation accident, and the method and system for alarming a nuclear power plant fuel operation accident provided in the embodiments of this application, the target decontamination factor corresponding to the target nuclide in the first time period and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period are first obtained; the target nuclide includes at least one of radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes the time from the occurrence of a fuel operation accident in the nuclear power plant to the Nth hour after the occurrence; the second time period includes the Nth hour to the Mth hour after the occurrence of the fuel operation accident, where M is greater than N; secondly, based on the target decontamination factor, the first release amount corresponding to the target nuclide in the first time period is determined; then, based on the total concentration of aerosol iodine, the fraction of iodine that is re-volatile in the spent pool in elemental form in the second time period is determined; then, based on the iodine fraction, the second release amount of elemental iodine in the second time period is determined; and finally, based on the first release amount and the second release amount, the source term of the nuclear power plant fuel operation accident is generated. In other words, in this embodiment of the application, by comprehensively considering the impact of the target decontamination factor, aerosol iodine concentration, and the proportion of iodine re-volatilized in elemental form in the second-period spent pool on the fuel operation accident source terms of the nuclear power plant, the accuracy of the determination of the fuel operation accident source terms of the nuclear power plant can be improved. Attached Figure Description

[0104] Figure 1 This illustration shows a flowchart of a method for determining the source term of a fuel operation accident in a nuclear power plant, as provided in an embodiment of this application.

[0105] Figure 2 This illustration shows another flowchart of the method for determining the source term of a fuel operation accident in a nuclear power plant, as provided in an embodiment of this application.

[0106] Figure 3 This illustration shows a structural schematic diagram of a device for determining the source term of a fuel operation accident in a nuclear power plant, as provided in an embodiment of this application. Detailed Implementation

[0107] To enable those skilled in the art to better understand the technical solutions of this application, the application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0108] The features and exemplary embodiments of various aspects of this application will now be described in detail. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain this application and are not configured to limit this application. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples of this application.

[0109] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0110] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0111] Extensive research by the inventors revealed that the pH value of the waste pool actually affects the conversion ratio of aerosol iodine to elemental iodine, which means that the accuracy of the fuel operation accident source items identified in related technologies needs to be improved.

[0112] Example 1

[0113] The method for determining the source term results of a fuel operation accident in a nuclear power plant provided in this application embodiment can be executed by a fuel operation accident source term result determination device and electronic equipment in the nuclear power plant. The following description takes the execution of the fuel operation accident source term result determination method in the nuclear power plant by electronic equipment as an example.

[0114] like Figure 1 As shown, the method for determining the source term of a fuel operation accident in a nuclear power plant provided in this application embodiment may include steps S110 to S150.

[0115] S110. Obtain the target decontamination factor corresponding to the target nuclide in the first time period, and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period; the target nuclide includes at least one of the following: radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes the period from the time of the fuel operation accident at the nuclear power plant to the Nth hour after the accident; the second time period includes the period from the Nth hour to the Mth hour after the fuel operation accident, where M is greater than N.

[0116] S120. Based on the target decontamination factor, determine the first release amount of the target nuclide in the first time period.

[0117] S130. Based on the total concentration of aerosol iodine, determine the proportion of iodine that is re-volatile in elemental form in the waste tank during the second time period.

[0118] S140. Determine the second release amount of elemental iodine in the second time period based on the iodine fraction.

[0119] S150. Based on the first and second release amounts, generate the fuel operation accident source term results for the nuclear power plant.

[0120] According to the method and apparatus for determining the source term of a nuclear power plant fuel operation accident, and the method and system for alarming a nuclear power plant fuel operation accident provided in the embodiments of this application, the target decontamination factor corresponding to the target nuclide in the first time period and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period are first obtained; the target nuclide includes at least one of radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes the time from the occurrence of a fuel operation accident in the nuclear power plant to the Nth hour after the occurrence; the second time period includes the Nth hour to the Mth hour after the occurrence of the fuel operation accident, where M is greater than N; secondly, based on the target decontamination factor, the first release amount corresponding to the target nuclide in the first time period is determined; then, based on the total concentration of aerosol iodine, the fraction of iodine that is re-volatile in the spent pool in elemental form in the second time period is determined; then, based on the iodine fraction, the second release amount of elemental iodine in the second time period is determined; and finally, based on the first release amount and the second release amount, the source term of the nuclear power plant fuel operation accident is generated. In other words, in this embodiment of the application, by comprehensively considering the impact of the target decontamination factor, aerosol iodine concentration, and the proportion of iodine re-volatilized in elemental form in the second-period spent pool on the fuel operation accident source terms of the nuclear power plant, the accuracy of the determination of the fuel operation accident source terms of the nuclear power plant can be improved.

[0121] The specific implementation methods for each of the above steps are described below.

[0122] In step S110, for example, N can be 2 and M can be 720. That is, the first time period includes the time from the occurrence of the fuel operation accident at the nuclear power plant to the second hour after the accident; the second time period includes the second hour to the 720th hour after the occurrence of the fuel operation accident at the nuclear power plant, that is, the second time period includes the time from the second hour to 30 days after the occurrence of the fuel operation accident at the nuclear power plant. It should be noted that the values ​​of N and M can be set according to the actual situation and are not limited here.

[0123] For example, the radioactive isotopes of the inert gas may include at least one of krypton-83m (Ke-83m), krypton-85 (Ke-85), krypton-85m (Ke-85m), krypton-87 (Ke-87), krypton-88 (Ke-88), xenon-131m (Xe-131m), xenon-133 (Xe-133), xenon-133m (Xe-133m), xenon-135 (Xe-135), and xenon-135m (Xe-135m).

[0124] For example, elemental iodine may include at least one of iodine-131 (elemental iodine), iodine-132 (elemental iodine), iodine-133 (elemental iodine), iodine-134 (elemental iodine), and iodine-135 (elemental iodine).

[0125] For example, organic iodine may include at least one of iodine-131 (organic iodine), iodine-132 (organic iodine), iodine-133 (organic iodine), iodine-134 (organic iodine), and iodine-135 (organic iodine).

[0126] For example, a spent fuel pool is also known as a spent fuel pool.

[0127] Therefore, in some implementations, the target nuclide includes elemental iodine.

[0128] Obtain the target decontamination factor corresponding to the target nuclide in the first time period, specifically including:

[0129] Obtain the rise time and diameter of the radioactive bubble;

[0130] Based on the bubble rise time and bubble diameter, the target decontamination factor corresponding to elemental iodine in the first time period is determined.

[0131] Extensive research by the inventors revealed that parameters such as the depth of the water layer above damaged fuel assemblies and the internal pressure of the fuel rods in nuclear power plants affect the target decontamination factor of elemental iodine. Assuming the water layer thickness above the damaged fuel assembly is between 5.79m and 7.01m, the target decontamination factor of elemental iodine is related to the internal pressure of the fuel rods. Based on this, in some examples, the rise time and diameter of radioactive bubbles are obtained, specifically including:

[0132] Obtain the internal pressure of the fuel rods;

[0133] The rise time of the entrained radioactive bubbles is determined based on the internal pressure of the fuel rod and formula (1).

[0134] Formula (1) includes:

[0135]

[0136] Where t is the bubble rise time; x is the internal pressure of the fuel rod;

[0137] The diameter of the radioactive bubble is determined based on the internal pressure of the fuel rod and formula (2);

[0138] Formula (2) includes:

[0139] d = -0.0002x + 1.0009 (2)

[0140] Where d is the diameter of the bubble.

[0141] For example, the unit of bubble rise time is seconds (s).

[0142] For example, the unit of bubble diameter is centimeters (cm).

[0143] For example, the unit of internal pressure of the fuel rod is pounds per square inch (psi).

[0144] In some examples, the target detergency factor corresponding to elemental iodine in the first time period is determined based on the bubble rise time and bubble diameter, specifically including:

[0145] Substituting the bubble rise time and bubble diameter into formula (3), the target decontamination factor corresponding to elemental iodine in the first time period is calculated.

[0146] Formula (3) includes:

[0147] DF I =81.046e 0.305(t / d) (3)

[0148] Where t is the bubble rise time; d is the bubble diameter; DF I The target decontamination factor corresponding to elemental iodine in the first time period.

[0149] It is understandable that by comprehensively considering the water depth above the damaged fuel assembly and the internal pressure of the fuel rod, the rise time and diameter of the bubbles can be determined, and then the target decontamination factor of elemental iodine can be determined based on the rise time and diameter of the bubbles. This can improve the accuracy of the target decontamination factor of elemental iodine, and further improve the accuracy of determining the source terms of fuel operation accidents in nuclear power plants.

[0150] In some embodiments, when the target nuclide includes a radioactive isotope of an inert gas and organic iodine, the target decontamination factor corresponding to the radioactive isotope of the inert gas and organic iodine is 1.

[0151] Of course, in other embodiments, the target decontamination factors corresponding to the radioactive isotopes of the inert gas and the organic iodine can also be other values.

[0152] In the second period, from 2 hours to 30 days after the fuel operation accident, the pH value of the wastewater affects the proportion of aerosol iodine converted into elemental iodine, causing a certain proportion of aerosol iodine to volatilize back into elemental iodine and be released from the wastewater.

[0153] Based on this, in some implementations, obtaining the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period specifically includes:

[0154] Obtain the sum of the molar numbers of each iodine isotope released from the gaps in damaged fuel assemblies in a nuclear power plant;

[0155] The total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is determined based on the sum of the molar numbers.

[0156] In some examples, the sum of the molar numbers of each iodine isotope released from the gaps in damaged fuel assemblies in a nuclear power plant is obtained, specifically including:

[0157] To obtain the decay constant of iodine, Avogadro's constant, and the iodine activity released from the gaps in damaged fuel assemblies in nuclear power plants;

[0158] Based on the decay constant, Avogadro's constant, and iodine activity, determine the sum of the molar numbers of each iodine isotope released from the gaps in damaged fuel assemblies in a nuclear power plant.

[0159] For example, the unit for the sum of moles is the mole (mol).

[0160] For example, the unit of iodine activity is becquerel (Bq).

[0161] For example, the decay constant is measured in seconds (s). -1 ).

[0162] For example, Avogadro's constant is 6.02 × 10⁻⁶. 23 mol -1 .

[0163] For example, the decay constant, Avogadro's constant, and iodine activity can all be pre-stored in the electronic device for direct later retrieval.

[0164] In some examples, the sum of the molar numbers of each iodine isotope released from the gaps in damaged fuel assemblies in nuclear power plants is determined based on the decay constant, Avogadro's constant, and iodine activity. These examples include:

[0165] Substituting the decay constant, Avogadro constant, and iodine activity into formula (4), the sum of the molar numbers of each iodine isotope released from the gaps in the damaged fuel assemblies in the nuclear power plant is calculated.

[0166] Formula (4) includes:

[0167]

[0168] Where, N I , gap The sum of the number of moles; A(I i ) represents iodine activity; I i It is an isotope of iodine; N is the decay constant; A is Avogadro's constant.

[0169] For example, I i May include I 131 and I 132 wait.

[0170] In some examples, the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is determined based on the sum of molar numbers, specifically including:

[0171] Obtain the free volume of the waste pool;

[0172] Substituting the sum of free volume and number of moles into formula (5), the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is calculated.

[0173] Formula (5) includes:

[0174]

[0175] Among them, C t This represents the total concentration of iodine in aerosols; N I，gap It is the sum of the number of moles; V pool For free volume.

[0176] For example, the total concentration of iodine in aerosols, C t The unit is moles per liter (mol / L).

[0177] For example, the free volume V pool The unit is liter (L).

[0178] For example, the free volume can be obtained by measurement or pre-stored in an electronic device for later direct retrieval.

[0179] In step S120, after the electronic device obtains the target decontamination factor corresponding to the target nuclide in the first time period and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period, it can also determine the first release amount corresponding to the target nuclide in the first time period based on the target decontamination factor.

[0180] For example, based on the target decontamination factor, the first release amount corresponding to the target nuclide in the first time period is determined, specifically including: obtaining the accumulation amount, release share and percentage of the target nuclide; multiplying the accumulation amount, release share and percentage as the first product; and using the ratio of the first product to the target decontamination factor as the first release amount corresponding to the target nuclide in the first time period.

[0181] In step S130, after determining the first release amount of the target nuclide in the first time period based on the target decontamination factor, the electronic device can also determine the proportion of iodine that is volatilized again in elemental form in the waste pool in the second time period based on the total concentration of aerosol iodine.

[0182] In some implementations, the fraction of iodine that re-volatilizes in elemental form in the waste tank during the second time period is determined based on the total concentration of aerosol iodine, specifically including:

[0183] Obtain the concentration ratio of elemental iodine to iodide ions in the waste pool;

[0184] The partition coefficient of iodine in aerosols is determined based on the total concentration and concentration ratio of iodine in aerosols.

[0185] Based on the allocation coefficient and the total concentration of aerosol iodine, the proportion of iodine that re-volatilizes in elemental form in the waste tank during the second time period is determined.

[0186] In some examples, the concentration ratio of iodine to iodide ions in the waste pool is obtained, specifically including:

[0187] Obtain the hydrogen ion concentration in the wastewater;

[0188] Substituting the hydrogen ion concentration into formula (6), the concentration ratio of iodine element to the square of iodide ions in the waste pool is calculated.

[0189] Formula (6) includes:

[0190] R i =[I2] / [I - ] 2 =C h 2 / (6.05×10 -1 +1.47×10 -9 C h (6)

[0191] Among them, R i For concentration ratio; Ch This represents the hydrogen ion concentration.

[0192] For example, the hydrogen ion concentration satisfies: C h =[H + ] = 10 -pH .

[0193] In some examples, the partition coefficient of iodine in aerosols is determined based on the total concentration and concentration ratio of iodine in the aerosols, specifically including:

[0194] Substitute the total concentration and concentration ratio of iodine in the aerosol into formula (7) to calculate the distribution coefficient of iodine in the aerosol.

[0195] Formula (7) includes:

[0196] B m =4C t +1 / R i (7)

[0197] Among them, R i For concentration ratio; C t B represents the total concentration of iodine in aerosols. m This is the allocation coefficient.

[0198] In some examples, the fraction of iodine that re-volatilizes in elemental form in the waste tank during the second time period is determined based on the allocation coefficient and the total concentration of aerosol iodine, specifically for:

[0199] Substituting the distribution coefficient and the total concentration of aerosol iodine into formula (8), the proportion of iodine that is volatilized again in elemental form in the waste pool during the second time period is calculated.

[0200] Formula (8) includes:

[0201]

[0202] Among them, B m C is the allocation coefficient; t X represents the total concentration of iodine in aerosols. e This refers to the iodine content.

[0203] In step S140, after determining the proportion of iodine that is re-volatile in elemental form in the waste tank during the second time period based on the total concentration of aerosol iodine, the electronic device can also determine the second release amount of elemental iodine during the second time period based on the iodine proportion.

[0204] In some implementations, the second release of elemental iodine in the second time period is determined based on the iodine fraction, specifically including:

[0205] The rate of elemental iodine release from the spent pool during the second time period was determined based on the iodine fraction.

[0206] The second release amount of elemental iodine in the second time period was determined based on the elemental iodine rate.

[0207] For example, the unit of iodine rate is per second.

[0208] In some examples, the rate of elemental iodine release from the spent pool during the second time period is determined based on the iodine fraction, specifically including:

[0209] Obtain the mass transfer coefficient, surface area of ​​the waste pool, and free volume;

[0210] The rate at which elemental iodine is released from the waste pool during the second time period is determined based on the mass transfer coefficient, surface area, free volume, and iodine fraction.

[0211] For example, the mass transfer coefficient is 3.66 × 10⁻⁶. -6 m / s.

[0212] In some examples, the rate of elemental iodine release from the spent tank during the second time period is determined based on the mass transfer coefficient, surface area, and free volume. Specifically, this includes:

[0213] The rate at which elemental iodine is released from the waste pool during the second time period is calculated by substituting the mass transfer coefficient, surface area, and free volume into formula (9).

[0214] Formula (9) includes:

[0215] λ e =K L X e S pool / V pool (9)

[0216] Where, λ e For the rate of elemental iodine; K L X is the mass transfer coefficient; e For iodine fraction; S pool V is the surface area; pool For free volume.

[0217] For example, the surface area S pool The unit is square meters (m) 2 Surface area can be obtained through measurement or pre-stored in electronic devices for later direct retrieval.

[0218] For example, the product of the iodine rate, the accumulated amount of elemental iodine, and the release duration is taken as the second amount of elemental iodine released in the second time period. The release duration is measured in seconds (s).

[0219] In step S150, after determining the second release amount of elemental iodine in the second time period based on the iodine fraction, the electronic device can also generate the fuel operation accident source term result of the nuclear power plant based on the first release amount and the second release amount.

[0220] For example, the results of a fuel operation accident at a nuclear power plant include a first release and a second release.

[0221] To better understand the fuel operation accident source term determination method provided in the embodiments of this application, a specific implementation method will be described below.

[0222] like Figure 2 As shown, the interstitial release fraction of the highest component gaseous fission product accumulation 100 hours (h) after reactor shutdown includes 4.85% elemental iodine, 95% aerosol iodine, 0.15% organic iodine, and inert gases.

[0223] The detailed calculation steps for determining the source term results of this fuel operation accident include the following.

[0224] Phase 1 (i.e., the first period): From the start of the accident to 2 hours later, assuming the water layer thickness above the damaged fuel assembly is between 5.79m and 7.01m, the decontamination factor (DF) of elemental iodine... I The target decontamination factor (i.e., the decontamination factor) is related to the internal pressure of the fuel rod and is calculated as follows:

[0225] DF I =81.046e 0.305(t / d) (3)

[0226]

[0227] d = -0.0002x + 1.0009(2)

[0228] Where x is the internal pressure of the fuel rod, in psi;

[0229] t is the ascent time of the radioactive bubble, in seconds;

[0230] d is the diameter of the radioactive bubble, in cm;

[0231] For other nuclides (such as krypton, xenon, etc.) and organic iodine in the gaps between damaged fuel rods, their decontamination factor (i.e., the target decontamination factor) is assumed to be 1; for aerosol iodine, it is conservatively assumed that it is completely dissolved in the pool water.

[0232] Phase 2 (i.e., the second period): 2 hours to 30 days after the accident, the pH value of the pool water affects the proportion of aerosol iodine converted into elemental iodine, causing a certain proportion of aerosol iodine to volatilize back into elemental iodine and be released from the pool water.

[0233] Calculate the sum of the moles of each iodine isotope released from the gap in the damaged fuel assembly (∑N). I，gap (unit: mol):

[0234]

[0235] Among them, I i Iodine isotopes, such as I 131 I 132 wait;

[0236] A(I i () represents the iodine activity released from the gaps in the damaged fuel assembly, in Bq.

[0237] λ Ii is the decay constant of iodine, in units of s⁻¹;

[0238] N A is Avogadro's constant, 6.02 × 10⁻⁶. 23 mol-1;

[0239] Calculate the total concentration of aerosol iodine (C) retained in the wastewater tank. t (unit: mol / L):

[0240]

[0241] Among them, V pool The free volume of the wastewater is expressed in liters (L).

[0242] Calculate [I2] / [I - ] 2 Concentration ratio (R) i ):

[0243] R i =[I2] / [I - ] 2 =C h 2 / (6.05×10 -14 +1.47×10 -9 C h (6)

[0244] Among them, C h =[H + ] = 10 -pH .

[0245] Calculate the proportion of iodine that re-volatilizes in the pool water as elemental iodine (X). e ):

[0246]

[0247] Among them, B m Satisfy: Bm =4C t +1 / R i (7).

[0248] In summary, the rate (λ) of elemental iodine released from the pool water in stage 2 e Unit s -1 ):

[0249] λe=K L X e S pool / V pool (9)

[0250] Among them, K L The mass transfer coefficient is 3.66 × 10⁻⁶. -6 m / s;

[0251] S pool The surface area of ​​the wastewater pool is expressed in meters (m²). 2 .

[0252] It is understood that the embodiments of this application propose a refined method for calculating the source terms of nuclear power plant fuel operation accidents (i.e., a method for determining the source terms of nuclear power plant fuel operation accidents). It comprehensively considers calculation parameters such as the water depth above the damaged fuel assembly, the internal pressure of the fuel rod, the surface area of ​​the spent fuel pool, the free volume, the pH value, and the amount of radioactive fission products accumulated in the spent fuel assembly at the initial moment of the accident. It analyzes in detail the process of fission products being released from the gaps in the damaged fuel cladding into the spent fuel pool in the early stage of the accident (stage 1), and the process of some aerosol iodine being volatilized from the pool into elemental iodine and then released into the environment (stage 2).

[0253] It should be noted that current traditional methods for calculating the source terms of fuel handling accidents occurring within the fuel building are overly conservative. These methods assume that radioactive materials escaping from the fuel pool into the fuel building are released into the environment within two hours, and conservatively assume that aerosol iodine is completely dissolved in the spent fuel pool. Furthermore, they conservatively assume that when the pool water has a low pH, the aerosol iodine entering the pool water instantly transforms into elemental iodine. This application proposes a refined method for calculating the source terms of nuclear power plant fuel handling accidents, comprehensively considering the impact of detailed design parameters of the nuclear power plant on the elemental iodine decontamination factor, aerosol iodine dissolution, and speciation processes. This application is the first to propose a method for calculating the source terms of nuclear power plant fuel handling accidents based on actual conditions, resulting in more refined and realistic assessments.

[0254] To better understand the method for determining the source term of a fuel operation accident in a nuclear power plant provided in the embodiments of this application, the following explanation is provided in conjunction with specific calculation examples.

[0255] Table 1 shows the highest accumulation of gaseous fission products in the components 100 hours after reactor shutdown. Iodine was classified into three forms: 95% aerosol iodine, 4.85% elemental iodine, and 0.15% organic iodine. Table 2 shows the proportion of fission products released from the fuel rod gaps. Table 3 shows the half-lives of various iodine isotopes.

[0256] Table 1

[0257]

[0258]

[0259] Table 2

[0260] Nuclide Release fraction I-131 0.07 I-132 0.07 Kr-85 0.4 Other noble gases 0.06

[0261] Table 3

[0262] Nuclide half-life (s -1 )]]> I-131 9.97E-07 I-132 8.36E-05 I-133 9.25E-06 I-134 2.20E-04 I-135 2.92E-05

[0263] The water depth above the damaged fuel assembly is 6.7 m, and the internal pressure of the fuel rod is approximately 9.48 MPa (1374.6 psi); the free volume of the spent fuel pool is 501 m³. 3 The surface area is 51m² 2 The pH value of the pool water is 4.8.

[0264] The detergency factor of elemental iodine in Stage 1 is calculated as follows:

[0265]

[0266] d=-0.0002x+1.0009=-0.0002×1374.6+1.0009=0.72598

[0267] DF I =81.046e 0.305(t / d) =81.046e 0.305(4.04417 / 0.72598) =443.2

[0268] For a Phase 1 accident with a release period of 0-2 hours, taking I-131 as an example, the amount of elemental iodine released is:

[0269] 7.94E+15×0.07×4.85% / 443.2=6.08E+10Bq

[0270] The organic iodine detergency factor is 1, and its release amount is:

[0271] 7.94E+15×0.07×0.15%=8.34E+11Bq

[0272] All aerosol iodine remained in the pool water and was not released during stage 1.

[0273] Taking Kr-85 as an example, the release amount of inert gas is:

[0274] 1.40E + 14 × 0.4 = 5.6E + 13Bq

[0275] Similarly, the release amounts of other iodine isotopes, organic iodine, and other inert gases in stage 1 can be obtained.

[0276] The rate of elemental iodine released from the pool water by aerosol iodine re-evaporation in stage 2 is calculated as follows:

[0277]

[0278] C h =[H + ] = 10 -pH =10 -4.8 =1.55×10 -5

[0279] R i =[I2] / [I - ] 2 =C h 2 / (6.05×10 -14 +1.47×10 -9 C h ) = 2997.55

[0280] B m =4C t +1 / R i = 4 × 1.79 × 10 -9 +1 / 2997.55 = 3.34 × 10 -4

[0281]

[0282] λe=K L X e S pool / V pool =4×10 -12

[0283] Phase 2 accident release periods range from 2 hours to 30 days. Taking I-131 as an example, the amount of aerosol iodine released as elemental iodine during different release periods in this phase is as follows:

[0284] 2-8 hours: 7.94E+15×4×10 -12 ×6×3600=6.52×10 8 Bq

[0285] 8-24 hours: 7.94E+15×4×10-12 ×16×3600=6.52×10 8 Bq

[0286] Days 1-4: 7.94E + 15 × 4 × 10 -12 ×3×24×3600=6.52×10 8 Bq

[0287] 4-30 days: 7.94E+15×4×10 -12 ×26×24×3600=6.52×10 8 Bq

[0288] Similarly, the amount of elemental iodine released from other iodine isotopes at different release periods can be obtained.

[0289] In summary, after considering detailed design parameters, the refined fuel operation accident source item results are shown in Table 4.

[0290] Table 4

[0291] Nuclide 0-2h 2-8h 8-24h 24-96h 96-720h I-131 (elemental iodine) 6.08E+10 6.86E+08 1.83E+09 8.23E+09 7.13E+10 I-132 (elemental iodine) 5.03E+10 5.68E+08 1.51E+09 6.81E+09 5.90E+10 I-133 (elemental iodine) 6.20E+09 6.99E+07 1.86E+08 8.39E+08 7.27E+09 I-134 (elemental iodine) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 I-135 (elemental iodine) 4.24E+06 4.79E+04 1.28E+05 5.74E+05 4.98E+06 I-131 (organic iodine) 8.34E+11 0.00E+00 0.00E+00 0.00E+00 0.00E+00 I-132 (organic iodine) 6.90E+11 0.00E+00 0.00E+00 0.00E+00 0.00E+00 I-133 (organic iodine) 8.49E+10 0.00E+00 0.00E+00 0.00E+00 0.00E+00 I-134 (organic iodine) 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 I-135 (organic iodine) 5.82E+07 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Kr-83m 9.78E+01 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Kr-85 5.60E+13 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Kr-85m 3.30E+07 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Kr-87 6.72E-10 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Kr-88 1.03E+04 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Xe-131m 8.46E+12 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Xe-133 9.18E+14 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Xe-133m 1.70E+13 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Xe-135 1.75E+12 0.00E+00 0.00E+00 0.00E+00 0.00E+00 Xe-135m 5.43E+09 0.00E+00 0.00E+00 0.00E+00 0.00E+00

[0292] Example 2

[0293] This application embodiment also provides a fuel operation accident alarm method for a nuclear power plant, which includes steps S210 to S230.

[0294] S110. Generate fuel operation accident source term results for the nuclear power plant according to the method for determining fuel operation accident source terms in Example 1.

[0295] S120. The accident consequence assessment model is used to process the source term results of the fuel operation accident to obtain the radioactive dose distribution corresponding to the source term results of the fuel operation accident.

[0296] S130. When the radioactive dose distribution is greater than or equal to a preset threshold, output alarm information. The alarm information is used to indicate that the radioactive dose distribution is greater than or equal to the preset threshold.

[0297] For example, an accident consequence assessment model is a type of computer simulation tool used to quantify the impact of radioactive material releases on people, the environment, and society. For instance, an accident consequence assessment model may include a Gaussian plume model, etc.

[0298] For example, the radioactive dose distribution includes the radioactive dose distribution within the factory area and the radioactive dose distribution in the public area outside the factory. An alarm is output when the radioactive dose distribution within the factory area is greater than or equal to its corresponding preset threshold, and / or when the radioactive dose distribution in the public area outside the factory is greater than or equal to its corresponding preset threshold.

[0299] For example, the preset threshold can be determined according to existing standards.

[0300] In this embodiment of the application, the source term results of the fuel operation accident of the nuclear power plant are first generated, and then the source term results of the fuel operation accident are processed by the accident consequence assessment model to obtain the radioactive dose distribution corresponding to the source term results of the fuel operation accident. Then, when the radioactive dose distribution is greater than or equal to a preset threshold, an alarm message is output so as to promptly remind the staff of abnormal radioactive dose.

[0301] Example 3

[0302] like Figure 3 As shown in the embodiment of this application, a device for determining the source term results of a fuel operation accident in a nuclear power plant is also provided. The device for determining the source term results of a fuel operation accident in a nuclear power plant includes a first acquisition module 201, a first determination module 202, a second determination module 203, a third determination module 204, and a generation module 205.

[0303] The first acquisition module 201 is used to acquire the target decontamination factor corresponding to the target nuclide in the first time period, and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period; the target nuclide includes at least one of radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes the period from the time of the fuel operation accident at the nuclear power plant to the Nth hour after the accident; the second time period includes the period from the Nth hour to the Mth hour after the fuel operation accident, where M is greater than N;

[0304] The first determining module 202, connected to the first acquiring module 201, is used to determine the first release amount of the target nuclide in the first time period based on the target decontamination factor.

[0305] The second determining module 203, connected to the first determining module 202, is used to determine the proportion of iodine that is re-volatile in elemental form in the waste pool during the second time period based on the total concentration of aerosol iodine.

[0306] The third determining module 204, connected to the second determining module 203, is used to determine the second release amount of elemental iodine in the second time period based on the iodine fraction.

[0307] The generation module 205, connected to the first determination module 202 and the third determination module 204, is used to generate the fuel operation accident source item results of the nuclear power plant based on the first release amount and the second release amount.

[0308] According to the nuclear power plant fuel operation accident source term determination device provided in the embodiments of this application, the target decontamination factor corresponding to the target nuclide in the first time period and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period are first obtained; the target nuclide includes at least one of radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes from the time of the fuel operation accident of the nuclear power plant to the Nth hour after the accident; the second time period includes from the Nth hour to the Mth hour after the fuel operation accident, where M is greater than N; secondly, based on the target decontamination factor, the first release amount corresponding to the target nuclide in the first time period is determined; then, based on the total concentration of aerosol iodine, the fraction of iodine that is re-volatile in elemental form in the spent pool in the second time period is determined; then, based on the iodine fraction, the second release amount of elemental iodine in the second time period is determined; and finally, based on the first release amount and the second release amount, the nuclear power plant fuel operation accident source term result is generated. In other words, in this embodiment of the application, by comprehensively considering the impact of the target decontamination factor, aerosol iodine concentration, and the proportion of iodine re-volatilized in elemental form in the second-period spent pool on the fuel operation accident source terms of the nuclear power plant, the accuracy of the determination of the fuel operation accident source terms of the nuclear power plant can be improved.

[0309] In some implementations, the first acquisition module 201 is specifically used for:

[0310] Obtain the rise time and diameter of the radioactive bubble;

[0311] Based on the bubble rise time and bubble diameter, the target decontamination factor corresponding to elemental iodine in the first time period is determined.

[0312] In some implementations, the first acquisition module 201 is specifically used for:

[0313] Obtain the internal pressure of the fuel rods;

[0314] The rise time of the entrained radioactive bubbles is determined based on the internal pressure of the fuel rod and formula (1).

[0315] Formula (1) includes:

[0316]

[0317] Where t is the bubble rise time; x is the internal pressure of the fuel rod;

[0318] The diameter of the radioactive bubble is determined based on the internal pressure of the fuel rod and formula (2);

[0319] Formula (2) includes:

[0320] d = -0.0002x + 1.0009 (2)

[0321] Where d is the diameter of the bubble.

[0322] In some implementations, the first acquisition module 201 is specifically used for:

[0323] Substituting the bubble rise time and bubble diameter into formula (3), the target decontamination factor corresponding to elemental iodine in the first time period is calculated.

[0324] Formula (3) includes:

[0325] DF I =81.046e 0.305(t / d) (3)

[0326] Where t is the bubble rise time; d is the bubble diameter; DF I The target decontamination factor corresponding to elemental iodine in the first time period.

[0327] In some embodiments, when the target nuclide includes a radioactive isotope of an inert gas and organic iodine, the target decontamination factor corresponding to the radioactive isotope of the inert gas and organic iodine is 1.

[0328] In some implementations, the first acquisition module 201 is specifically used for:

[0329] Obtain the sum of the molar numbers of each iodine isotope released from the gaps in damaged fuel assemblies in a nuclear power plant;

[0330] The total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is determined based on the sum of the molar numbers.

[0331] In some implementations, the first acquisition module 201 is specifically used for:

[0332] To obtain the decay constant of iodine, Avogadro's constant, and the iodine activity released from the gaps in damaged fuel assemblies in nuclear power plants;

[0333] Based on the decay constant, Avogadro's constant, and iodine activity, determine the sum of the molar numbers of each iodine isotope released from the gaps in damaged fuel assemblies in a nuclear power plant.

[0334] In some implementations, the first acquisition module 201 is specifically used for:

[0335] Substituting the decay constant, Avogadro constant, and iodine activity into formula (4), the sum of the molar numbers of each iodine isotope released from the gaps in the damaged fuel assemblies in the nuclear power plant is calculated.

[0336] Formula (4) includes:

[0337]

[0338] Where, N I，gap The sum of the number of moles; A(I i) represents iodine activity; N is the decay constant; A is Avogadro's constant.

[0339] In some implementations, the first acquisition module 201 is specifically used for:

[0340] Obtain the free volume of the waste pool;

[0341] Substituting the sum of free volume and number of moles into formula (5), the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is calculated.

[0342] Formula (5) includes:

[0343]

[0344] Among them, C t This represents the total concentration of iodine in aerosols; N I，gap It is the sum of the number of moles; V pool For free volume.

[0345] In some implementations, the second determining module 203 is specifically used for:

[0346] Obtain the concentration ratio of elemental iodine to iodide ions in the waste pool;

[0347] The partition coefficient of iodine in aerosols is determined based on the total concentration and concentration ratio of iodine in aerosols.

[0348] Based on the allocation coefficient and the total concentration of aerosol iodine, the proportion of iodine that re-volatilizes in elemental form in the waste tank during the second time period is determined.

[0349] In some implementations, the second determining module 203 is specifically used for:

[0350] Obtain the hydrogen ion concentration in the wastewater;

[0351] Substituting the hydrogen ion concentration into formula (6), the concentration ratio of iodine element to the square of iodide ions in the waste pool is calculated.

[0352] Formula (6) includes:

[0353] R i =[I2] / [I - ] 2 =C h 2 / (6.05×10 -14 +1.47×10 -9 C h (6)

[0354] Among them, R i For concentration ratio; C h This represents the hydrogen ion concentration.

[0355] In some implementations, the second determining module 203 is specifically used for:

[0356] Substitute the total concentration and concentration ratio of iodine in the aerosol into formula (7) to calculate the distribution coefficient of iodine in the aerosol.

[0357] Formula (7) includes:

[0358] B m =4C t +1 / R i (7)

[0359] Among them, R i For concentration ratio; C t B represents the total concentration of iodine in aerosols. m This is the allocation coefficient.

[0360] In some implementations, the second determining module 203 is specifically used for:

[0361] Substituting the distribution coefficient and the total concentration of aerosol iodine into formula (8), the proportion of iodine that is volatilized again in elemental form in the waste pool during the second time period is calculated.

[0362] Formula (8) includes:

[0363]

[0364] Among them, B m C is the allocation coefficient; t X represents the total concentration of iodine in aerosols. e This refers to the iodine content.

[0365] In some implementations, the third determining module 204 is specifically used for:

[0366] The rate of elemental iodine release from the spent pool during the second time period was determined based on the iodine fraction.

[0367] The second release amount of elemental iodine in the second time period was determined based on the elemental iodine rate.

[0368] In some implementations, the third determining module 204 is specifically used for:

[0369] Obtain the mass transfer coefficient, surface area of ​​the waste pool, and free volume;

[0370] The rate at which elemental iodine is released from the waste pool during the second time period is determined based on the mass transfer coefficient, surface area, free volume, and iodine fraction.

[0371] In some implementations, the third determining module 204 is specifically used for:

[0372] The rate at which elemental iodine is released from the waste pool during the second time period is calculated by substituting the mass transfer coefficient, surface area, and free volume into formula (9).

[0373] Formula (9) includes:

[0374] λ e =K L X e S pool / V poo (9)

[0375] Where, λ e For the rate of elemental iodine; K L X is the mass transfer coefficient; e For iodine fraction; S pool V is the surface area; pool For free volume.

[0376] The nuclear power plant fuel operation accident source term result determination device provided in this application embodiment has the beneficial effects and implementation methods of the nuclear power plant fuel operation accident source term result determination method provided in Embodiment 1 of this application. For details, please refer to the specific description of the nuclear power plant fuel operation accident source term result determination method in Embodiment 1 above. This embodiment will not repeat the description here.

[0377] Example 4

[0378] This application also provides a fuel operation accident alarm system for a nuclear power plant. The fuel operation accident alarm system for the nuclear power plant includes:

[0379] Example 3 describes a device for determining the source terms of a nuclear power plant's fuel operation accident, used to generate the source terms of a nuclear power plant's fuel operation accident.

[0380] The processing device, connected to the fuel operation accident source term result determination device of the nuclear power plant, is used to process the fuel operation accident source term results using an accident consequence assessment model to obtain the radioactive dose distribution corresponding to the fuel operation accident source term results.

[0381] The output device, connected to the processing device, is used to output alarm information when the radioactive dose distribution is greater than or equal to a preset threshold. The alarm information is used to indicate that the radioactive dose distribution is greater than or equal to the preset threshold.

[0382] The nuclear power plant fuel operation accident alarm system provided in this application embodiment has the beneficial effects and implementation methods of the nuclear power plant fuel operation accident alarm method provided in embodiment 2 of this application. For details, please refer to the specific description of the nuclear power plant fuel operation accident alarm method in embodiment 2 above. This embodiment will not repeat the description here.

[0383] Example 5

[0384] This application provides an electronic device, including a memory and a processor. The memory stores a computer program, and the processor is configured to run the computer program to execute the method for determining the source item result of a fuel operation accident in a nuclear power plant in Embodiment 1 or the method for alarming a fuel operation accident in a nuclear power plant in Embodiment 2.

[0385] The memory is connected to the processor. The memory can be flash memory, read-only memory or other types of memory. The processor can be a central processing unit or a microcontroller.

[0386] Example 6

[0387] This embodiment provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the method for determining the source item of a nuclear power plant's fuel operation accident in Embodiment 1 or the method for alarming a nuclear power plant's fuel operation accident in Embodiment 2.

[0388] The computer-readable storage medium includes volatile or non-volatile, removable or non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, computer program modules, or other data). Computer-readable storage media include, but are not limited to, RAM (Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory or other memory technologies, CD-ROM (Compact Disc Read-Only Memory), DVD or other optical disc storage, cartridges, magnetic tapes, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer.

[0389] Example 7

[0390] This application also provides a computer program product in which, when the instructions in the computer program product are executed by the processor of an electronic device, the electronic device executes the method for determining the source item result of a fuel operation accident in a nuclear power plant as in Embodiment 1 or the method for alarming a fuel operation accident in a nuclear power plant as in Embodiment 2.

[0391] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this application, and this application is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this application, and these modifications and improvements are also considered to be within the scope of protection of this application.

Claims

1. A method for determining the source terms of a fuel operation accident in a nuclear power plant, characterized in that, include: Obtain the target decontamination factor corresponding to the target nuclide in the first time period, and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period; The target nuclide includes at least one of radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes the period from the time of the fuel operation accident at the nuclear power plant to the Nth hour after the accident; the second time period includes the period from the Nth hour to the Mth hour after the fuel operation accident, where M is greater than N; Based on the target decontamination factor, determine the first release amount of the target nuclide during the first time period; Based on the total concentration of iodine in the aerosol, determine the proportion of iodine that is re-volatile in elemental form in the waste pool during the second time period; Based on the iodine fraction, determine the second release amount of elemental iodine during the second time period; Based on the first release amount and the second release amount, the fuel operation accident source term results of the nuclear power plant are generated.

2. The method according to claim 1, characterized in that, The target nuclide includes elemental iodine. The acquisition of the target decontamination factor corresponding to the target nuclide in the first time period specifically includes: Obtain the rise time and diameter of the radioactive bubble; Based on the bubble rise time and the bubble diameter, the target decontamination factor corresponding to the elemental iodine in the first time period is determined.

3. The method according to claim 2, characterized in that, The acquisition of the rise time and diameter of the radioactive bubble specifically includes: Obtain the internal pressure of the fuel rods; The rise time of the radioactive bubble is determined based on the internal pressure of the fuel rod and formula (1); Formula (1) includes: Where t is the bubble rise time; x is the internal pressure of the fuel rod; The diameter of the radioactive bubble is determined based on the internal pressure of the fuel rod and formula (2); Formula (2) includes: d = -0.0002x + 1.0009 (2) Where d is the diameter of the bubble.

4. The method according to claim 2, characterized in that, The step of determining the target decontamination factor corresponding to elemental iodine in the first time period based on the bubble rise time and the bubble diameter specifically includes: Substituting the bubble rise time and bubble diameter into formula (3), the target decontamination factor corresponding to the element iodine in the first time period is calculated; Formula (3) includes: DF I =81.046e 0.305 (t / d) (3) Where t is the bubble rise time; d is the bubble diameter; DF I The target decontamination factor corresponding to the element iodine during the first time period.

5. The method according to claim 1, characterized in that, When the target nuclide includes a radioactive isotope of an inert gas and the organic iodine, the target decontamination factor corresponding to the radioactive isotope of the inert gas and the organic iodine is 1.

6. The method according to claim 1, characterized in that, Obtain the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period, specifically including: Obtain the sum of the molar numbers of each iodine isotope released from the gaps in the damaged fuel assemblies in the nuclear power plant; Based on the sum of the molar numbers, the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is determined.

7. The method according to claim 6, characterized in that, The step of obtaining the sum of the molar numbers of each iodine isotope released from the gaps in the damaged fuel assemblies of the nuclear power plant specifically includes: The decay constant, Avogadro's constant, and iodine activity released from the gaps in the damaged fuel assemblies of the nuclear power plant were obtained. Based on the decay constant, the Avogadro constant, and the iodine activity, determine the sum of the molar numbers corresponding to each iodine isotope released from the gaps in the damaged fuel assemblies in the nuclear power plant.

8. The method according to claim 7, characterized in that, The determination of the sum of moles of each iodine isotope released from the gaps in the damaged fuel assemblies of the nuclear power plant based on the decay constant, the Avogadro constant, and the iodine activity specifically includes: Substituting the decay constant, the Avogadro constant, and the iodine activity into formula (4), the sum of the molar numbers of each iodine isotope released from the gaps in the damaged fuel assemblies in the nuclear power plant is calculated. Formula (4) includes: Where, N I，gap The sum of the stated number of moles; A(I i ) represents the iodine activity; I i It is an isotope of iodine; N is the decay constant; A Let be the Avogadro constant.

9. The method according to claim 6, characterized in that, The determination of the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period based on the sum of the molar numbers specifically includes: Obtain the free volume of the waste pool; Substituting the sum of the free volume and the number of moles into formula (5), the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period is calculated. Formula (5) includes: Among them, C t The total concentration of iodine in the aerosol; N I，gap V is the sum of the number of moles; pool The free volume is the aforementioned free volume.

10. The method according to claim 1, characterized in that, The determination of the proportion of iodine re-volatilized in elemental form in the waste pool during the second time period based on the total aerosol iodine concentration specifically includes: Obtain the concentration ratio of elemental iodine to iodide ions in the waste pool; The partition coefficient of iodine in the aerosol is determined based on the total concentration of iodine in the aerosol and the concentration ratio. Based on the allocation coefficient and the total concentration of aerosol iodine, the proportion of iodine that re-volatilizes in elemental form in the waste pool during the second time period is determined.

11. The method according to claim 10, characterized in that, Obtaining the concentration ratio of iodine element to iodide ions in the waste pool specifically includes: Obtain the hydrogen ion concentration in the wastewater. Substituting the hydrogen ion concentration into formula (6), the concentration ratio of iodine element to the square of iodide ions in the waste pool is calculated; Formula (6) includes: R i =[I2] / [I - ] 2 =C h 2 / (6.05×10 -1 +1.47×10 -9 C h ) (6) Among them, R i The concentration ratio is C. h The hydrogen ion concentration is [value missing].

12. The method according to claim 10, characterized in that, The determination of the partition coefficient of iodine in the aerosol based on the total concentration of iodine in the aerosol and the concentration ratio specifically includes: Substituting the total concentration of iodine in the aerosol and the concentration ratio into formula (7), the distribution coefficient of iodine in the aerosol is calculated; Formula (7) includes: B m =4C t +1 / R i (7) Among them, R i The concentration ratio is C. t B is the total concentration of iodine in the aerosol; m The allocation coefficient is denoted as .

13. The method according to claim 10, characterized in that, The determination of the proportion of iodine re-volatilized in elemental form in the waste pool during the second time period, based on the allocation coefficient and the total concentration of aerosol iodine, is specifically used for: Substituting the allocation coefficient and the total concentration of aerosol iodine into formula (8), the proportion of iodine that is re-volatile in elemental form in the waste pool during the second time period is calculated. Formula (8) includes: Among them, B m C is the allocation coefficient; t X represents the total iodine concentration in the aerosol; e The iodine content is [the specified percentage].

14. The method according to claim 1, characterized in that, The determination of the second release amount of elemental iodine during the second time period based on the iodine fraction specifically includes: The rate at which elemental iodine is released from the waste pool during the second time period is determined based on the iodine fraction. Based on the iodine rate, the second release amount of elemental iodine during the second time period is determined.

15. The method according to claim 14, characterized in that, The step of determining the rate of elemental iodine release from the spent iodine pool during the second time period based on the iodine fraction specifically includes: Obtain the mass transfer coefficient, the surface area of ​​the waste pool, and the free volume; The rate at which elemental iodine is released from the waste pool during the second time period is determined based on the mass transfer coefficient, the surface area, the free volume, and the iodine fraction.

16. The method according to claim 15, characterized in that, The step of determining the rate of elemental iodine release from the waste pool during the second time period based on the mass transfer coefficient, the surface area, and the free volume specifically includes: The rate at which elemental iodine is released from the waste pool during the second time period is calculated by substituting the mass transfer coefficient, the surface area, and the free volume into formula (9). Formula (9) includes: λ e =K L X e S pool / V pool (9) Where, λ e The rate of iodine in the element; K L X is the mass transfer coefficient; e The iodine content; S pool V is the surface area; pool The free volume is the aforementioned free volume.

17. A method for alarming fuel operation accidents in a nuclear power plant, characterized in that, include: The method for determining the fuel operation accident source term results of a nuclear power plant according to any one of claims 1 to 16 generates the fuel operation accident source term results of the nuclear power plant. The accident consequence assessment model was used to process the source term results of the fuel operation accident to obtain the radioactive dose distribution corresponding to the source term results of the fuel operation accident. If the radiation dose distribution is greater than or equal to a preset threshold, an alarm message is output, which indicates that the radiation dose distribution is greater than or equal to the preset threshold.

18. A device for determining the source term results of a fuel operation accident in a nuclear power plant, characterized in that, include: The first acquisition module is used to acquire the target decontamination factor corresponding to the target nuclide in the first time period, and the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant in the second time period; the target nuclide includes at least one of radioactive isotopes of inert gases, elemental iodine, and organic iodine; the first time period includes the period from the time of the fuel operation accident of the nuclear power plant to the Nth hour after the accident; the second time period includes the period from the Nth hour to the Mth hour after the fuel operation accident, where M is greater than N; The first determining module, connected to the first acquiring module, is used to determine the first release amount of the target nuclide in the first time period based on the target decontamination factor. The second determining module, connected to the first determining module, is used to determine the proportion of iodine that is re-volatile in elemental form in the waste pool during the second time period based on the total concentration of iodine in the aerosol. The third determining module, connected to the second determining module, is used to determine the second release amount of elemental iodine during the second time period based on the iodine fraction. A generation module, connected to the first determining module and the third determining module, is used to generate fuel operation accident source item results for the nuclear power plant based on the first release amount and the second release amount.

19. The apparatus according to claim 18, characterized in that, The target nuclide includes elemental iodine. The first acquisition module is specifically used for: Obtain the rise time and diameter of the radioactive bubble; Based on the bubble rise time and the bubble diameter, determine the target decontamination factor corresponding to the elemental iodine during the first time period; And / or, The first acquisition module is specifically used for: Obtain the sum of the molar numbers of each iodine isotope released from the gaps in the damaged fuel assemblies in the nuclear power plant; Based on the sum of the molar numbers, determine the total concentration of aerosol iodine retained in the spent pool of the nuclear power plant during the second time period; And / or, The second determining module is specifically used for: Obtain the concentration ratio of elemental iodine to iodide ions in the waste pool; The partition coefficient of iodine in the aerosol is determined based on the total concentration of iodine in the aerosol and the concentration ratio. Based on the allocation coefficient and the total concentration of aerosol iodine, the proportion of iodine that re-volatilizes in elemental form in the waste pool during the second time period is determined.

20. A fuel operation accident alarm system for a nuclear power plant, characterized in that, include: The apparatus for determining the fuel operation accident source term results of a nuclear power plant according to any one of claims 18 to 19 is used to generate the fuel operation accident source term results of the nuclear power plant. The processing device is connected to the fuel operation accident source term result determination device of the nuclear power plant, and is used to process the fuel operation accident source term result using an accident consequence assessment model to obtain the radioactive dose distribution corresponding to the fuel operation accident source term result. An output device, connected to the processing device, is used to output alarm information when the radioactive dose distribution is greater than or equal to a preset threshold. The alarm information is used to indicate that the radioactive dose distribution is greater than or equal to the preset threshold.

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