A method for assessing the atmospheric environmental toxicity risk of a uranium processing and fuel fabrication facility

Abstract

The present application relates to a kind of method for evaluating the atmospheric environment toxicity risk of uranium processing and fuel manufacturing facilities.The present application provides reference for carrying out environmental risk analysis and quantitative evaluation of uranium processing and fuel manufacturing facilities.Using the method provided by the present application, according to the process characteristics of uranium processing and fuel manufacturing facilities, the leakage scenarios of dangerous chemical substance supply container in three leakage positions and three leakage apertures are analyzed, the public individual risk of each leakage scenario under 6 kinds of atmospheric diffusion conditions is calculated, the public individual environmental risk value of each residential area is calculated, and the environmental risk value result is compared with the regulatory requirements, to evaluate whether the environmental risk of the uranium processing and fuel manufacturing facilities meets the regulatory requirements of the regulatory department on environmental risk.

Description

Technical Field

[0001] This invention belongs to the field of radiation environmental risk assessment technology for nuclear facilities, specifically relating to a method for assessing the atmospheric environmental toxicity risk of uranium processing and fuel manufacturing facilities. Background Technology

[0002] The production process in uranium processing and fuel manufacturing facilities requires the use of large quantities of chemicals, including anhydrous hydrogen fluoride, fluorine, hydrogen, and liquid ammonia. Most of these substances are toxic and harmful gases, with hydrogen and liquid ammonia posing a risk of combustion and explosion.

[0003] Most of the uranium processing and fuel manufacturing facilities in the country are located within large nuclear bases. Explosions and fires mainly pose safety risks to facilities in the vicinity, while environmental risks primarily involve the large-scale release of hazardous chemicals.

[0004] The Safety Regulations for Civil Nuclear Fuel Cycle Facilities (HAF301) provide detailed regulations on radiation safety in the design and operation of uranium processing and fuel manufacturing facilities. However, these regulations do not cover non-radiation safety issues unless a non-radiation safety issue can cause radiation hazards.

[0005] Appendix II of the "Interim Provisions on the Supervision and Management of Major Hazard Sources of Hazardous Chemicals" (Order No. 40 of the State Administration of Work Safety) issued by the former State Administration of Work Safety stipulates that the personal risk borne by important targets and sensitive locations around hazardous chemical substance units should meet the following requirements: 1) The risk borne by important targets and sensitive locations around hazardous chemical substance units should not exceed 1×10 -6 / year; 2) Highly sensitive locations (schools, hospitals, etc.) and special high-density locations (such as large stadiums, etc.) shall not exceed 3×10 -7 / Year.

[0006] Environmental risk analysis should be conducted using a single storage unit (such as a single container or a single process pipeline) as the unit of analysis. The analysis should focus on the concentration contribution of a single storage unit to the surrounding environment when it leaks, and calculate the environmental risk of a single storage unit leaking.

[0007] Immediately Dangerous To Life or Health Values ​​(IDLH) are air concentration values ​​(IDLH values) established by the National Institute for Occupational Safety and Health (NIOSH) in the United States that pose an immediate danger to life or health. IDLHs characterize the concentration limits of chemicals exposed to high-risk concentrations and conditions. IDLH values ​​specify the highest concentration level at which an occupational worker can escape from a high-risk environment in the event of a malfunction in respiratory protection equipment. This concentration value can be used as a screening threshold for calculating individual environmental risk.

[0008] The "Hygienic Design Standard for Industrial Enterprises" (TJ36-79) has been superseded by the newly published "Hygienic Design Standard for Industrial Enterprises: Chemical Hazardous Factors" (GBZ2.1-2019). However, TJ36-79 specifies the maximum permissible concentration of hazardous chemicals in residential areas. This standard value is still referenced in environmental risk assessments and can be used as the toxicity endpoint for environmental risk calculations. Summary of the Invention

[0009] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a method for assessing the atmospheric environmental toxicity risk of uranium processing and fuel manufacturing facilities. This method can be used to conduct quantitative assessments of the environmental risks of uranium processing and fuel manufacturing facilities based on their production characteristics, so as to assess whether the environmental risks of hazardous chemicals in such facilities meet the regulatory requirements of regulatory authorities.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities, comprising the following steps:

[0011] S1. Analyze the leakage scenarios of hazardous chemicals and estimate the leakage source terms;

[0012] The analysis of the leakage scenarios considers three leakage locations of the feeding container: top, middle, and bottom. Each leakage location includes three leakage scenarios with different orifice diameters: small orifice leakage, medium orifice leakage, and large orifice leakage. The leakage source term is the leakage rate of each leakage scenario.

[0013] S2. Calculate the radius of influence of the leaked hazardous chemical substance;

[0014] The radius of influence includes the radius of the IDLH concentration point and the radius of the toxicity endpoint.

[0015] S3. Assess environmental risk areas;

[0016] If the radius of the toxic endpoint is not greater than the radius of the plant site boundary, the environmental safety of the facility meets the requirements of the national regulatory authorities; if the radius of the toxic endpoint is greater than the radius of the plant site boundary, further assessment of the low-concentration area, medium-concentration area, and high-concentration area is required.

[0017] S4. Analyze and quantify the risks;

[0018] Quantitatively calculate the individual environmental risk values ​​of the public in each residential area in the high-concentration zone, and analyze and explain whether the individual environmental risk values ​​of the public meet the requirements of the national regulatory authorities for individual risk.

[0019] Furthermore, the diameter of the small hole leakage is 1 mm, the diameter of the medium hole leakage is 10 mm, and the diameter of the large hole leakage is 50 mm.

[0020] Furthermore, when estimating the leakage source, the highest pressure and highest temperature set by the process in which the feeding container is located are used for calculation and analysis.

[0021] Furthermore, when calculating the radius of influence, the atmospheric stability categories that need to be considered in calculating the atmospheric diffusion concentration of hazardous chemicals include: Category B, Category D, Category E, and Category F.

[0022] Furthermore, when calculating the radius of influence, a steady-state model is used to calculate the atmospheric diffusion concentration of hazardous chemicals.

[0023] Furthermore, based on the IDLH limits for hazardous chemicals, the IDLH concentration point radii for different leakage scenarios and atmospheric diffusion conditions were obtained.

[0024] Furthermore, based on the concentration values ​​of the toxic endpoints of hazardous chemicals, the toxic endpoint radii are obtained under different leakage scenarios and different atmospheric diffusion conditions.

[0025] Furthermore, with the release point of the hazardous chemical substance as the center, the distance between the low concentration zone and the center is greater than the radius of the toxic endpoint;

[0026] The distance between the intermediate concentration zone and the center is less than the radius of the toxic endpoint but greater than the radius of the IDLH concentration point.

[0027] The distance between the high-concentration zone and the center is less than the radius of the IDLH concentration point.

[0028] Furthermore, in step S4, the quantitative calculation of the risk includes the following steps:

[0029] S41. Calculate the individual mortality risk of each settlement in the high-concentration area;

[0030] The formula for calculating the individual mortality risk is as follows:

[0031]

[0032] In the formula:

[0033] P i Let be the probability of an individual in the public dying acutely from inhaling a hazardous chemical substance in the i-th leakage scenario;

[0034] erf is the error function. ;

[0035] Y is an intermediate quantity, and the formula for calculating Y is Y = a + b·ln(C n ·t e ); where C is the concentration, in ppm; t eThe exposure time to this concentration is expressed in minutes, and the calculation takes the time of release of the hazardous chemical substance; a, b, and n are the toxicity constants of the hazardous chemical substance.

[0036] S42. Calculate the individual risk value for the public in each leakage scenario;

[0037] The risk value for the general public under certain atmospheric diffusion conditions in the i-th leakage scenario is calculated using the following formula:

[0038] ΔIR M,u,i =f i ×P M ×P u ×P i

[0039] In the formula:

[0040] ΔIR M,u,i The risk to the public under certain atmospheric diffusion conditions in the i-th leakage scenario;

[0041] f i Let be the annual failure probability of the i-th leakage scenario;

[0042] P M ×P u The three-dimensional joint frequency of atmospheric stability M and wind speed u under a certain wind direction;

[0043] P i Let be the probability of an individual in the public dying acutely from inhaling a hazardous chemical substance in the i-th leakage scenario;

[0044] S43. Calculate the individual environmental risk value (IR) for each residential area;

[0045] The individual public environmental risk value (IR) for each residential area is calculated using the following formula:

[0046] IR=Σ i ×Σ M ×Σ u ΔIR M,u,i

[0047] In the formula:

[0048] i represents the i-th leakage scenario;

[0049] M represents atmospheric stability;

[0050] u represents wind speed;

[0051] ΔIR M,u,i Let be the risk to the general public under certain atmospheric diffusion conditions in the i-th leakage scenario.

[0052] Furthermore, the calculated individual public environmental risk value (IR) for each residential area is compared with 1×10⁻⁶. -6 For comparison per year, if the individual public environmental risk value (IR) of a residential area is ≥1×10 -6 If the environmental risk of a settlement is less than 1 × 10⁶ per year, then the environmental risk of that settlement is unacceptable. -6 If the environmental risk level of the settlement is within a certain range per year, then the environmental risk level of the settlement is acceptable.

[0053] The beneficial effects of this invention are as follows: The method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities provided by this invention can analyze leakage scenarios at three leakage locations and with three leakage orifice diameters for hazardous chemical supply containers, based on the technological characteristics of the uranium processing and fuel manufacturing facilities. It calculates the individual public risk and the individual public environmental risk value for each residential site under six types of atmospheric diffusion conditions for each leakage scenario. The environmental risk values ​​are then compared with the requirements of regulatory authorities to evaluate whether the environmental risk of this type of uranium processing and fuel manufacturing facility meets the regulatory requirements for environmental risk. This invention provides a reference for conducting environmental risk analysis and quantitative calculation and evaluation of uranium processing and fuel manufacturing facilities. Attached Figure Description

[0054] Figure 1 A schematic flowchart illustrating a method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities, provided as an embodiment of the present invention. Detailed Implementation

[0055] The technical solutions in the embodiments of the present invention will be further clearly and completely described below with reference to the accompanying drawings and examples. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0056] like Figure 1 As shown, this embodiment provides a method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities, analyzing the environmental risk of a specific hazardous chemical substance. The method includes the following steps:

[0057] S1. Analyze the leakage scenarios of hazardous chemicals and estimate the leakage source terms;

[0058] The process piping storage capacity of uranium processing and fuel manufacturing facilities is less than the storage capacity of the feed containers for hazardous chemicals, and the analysis of hazardous chemical leakage scenarios focuses on the feed containers.

[0059] The leakage scenario should consider three leakage locations: the top, middle, and bottom of the feeding container. The leakage orifice diameter for each location should be a small hole (1mm), a medium hole (10mm), and a large hole (50mm), respectively. That is, each leakage location includes leakage at three different orifice diameters: small hole leakage, medium hole leakage, and large hole leakage. The leakage source term refers to the leakage rate of each leakage scenario, i.e., the leakage amount per unit time in each leakage scenario.

[0060] When estimating the leakage sources, the highest pressure and highest temperature set by the process in which the feed container is located should be used for calculation and analysis.

[0061] When estimating the aforementioned leakage sources, the activation of dedicated safety facilities (or equipment) and personnel response are not taken into account.

[0062] In a specific embodiment, the hazardous chemical substance leaked in step S1 is anhydrous hydrogen fluoride (AHF), the source of leakage and the object of analysis of the leakage scenario is the AHF supply container, and the leakage accident is that the AHF supply container, which is in the process of supplying materials, leaked.

[0063] At the time of the leak, the temperature inside the AHF feed container was 25°C.

[0064] During the analysis of leakage scenarios, it is necessary to consider the three leakage locations located at the top, middle, and bottom of the AHF feeding container. Furthermore, it is necessary to consider the different orifice diameters at each leakage location: small (1mm), medium (10mm), and large (50mm).

[0065] Based on the highest pressure and highest temperature set in the process where the AHF feeding container is located, calculate the leakage source items for each leakage scenario, that is, calculate the leakage rate of each leakage location when the leakage orifice diameter is small, medium, or large, respectively, under the highest pressure and highest temperature set in the process where the AHF feeding container is located.

[0066] The analysis of leakage rate, leakage volume, and leakage time is relatively complex. Manual calculations can be performed using the formulas in Appendix F of the "Technical Guidelines for Environmental Risk Assessment of Construction Projects" (HJ169-2018), or relevant software can be used for analysis. In this embodiment, the ALOHA software released by the U.S. Environmental Protection Agency was used for analysis and calculation, resulting in the leakage source items for each leakage scenario shown in Table 1, i.e., the leakage rate at each leakage location when the orifice diameter is small, medium, or large.

[0067] Table 1. Leakage source items for each leakage scenario

[0068]

[0069] The release method for each leakage scenario is ground release.

[0070] S2. Calculate the radius of influence of the leaked hazardous chemical substance;

[0071] To calculate the impact radius of a leaked hazardous chemical substance, it is necessary to calculate its atmospheric diffusion concentration. This calculation requires consideration of various atmospheric diffusion conditions. In this embodiment, the atmospheric stability categories to be considered include: Category B, Category D, Category E, and Category F. For Category B atmospheric stability, the wind speed is 4 m / s; for Category D, the wind speeds are 1.5 m / s, 4 m / s, and 8 m / s respectively; for Category E, the wind speed is 4 m / s; and for Category F, the wind speed is 1.5 m / s.

[0072] The calculation of the radius of influence should take into account both the radius of the IDLH concentration point and the radius of the toxic endpoint.

[0073] The toxic endpoint is the concentration point at which a hazardous chemical substance will not cause irreversible effects on individuals in the public. The concentration value of the toxic endpoint can be taken from the maximum permissible concentration of hazardous substances in the residential area shown in Table 1 of the TJ36-79 standard, or from the AEGLs Level 1 limit for 60 minutes of exposure published by the U.S. Environmental Protection Agency.

[0074] The IDLH concentration point is the concentration point at which the atmospheric dispersion concentration of a hazardous chemical substance reaches the IDLH limit; the IDLH limit is the limit level published by the National Institute for Occupational Safety and Health (NIOSH) in the United States.

[0075] When calculating the radius of influence, the radius of the IDLH concentration point and the radius of the toxicity endpoint should be given separately.

[0076] The atmospheric diffusion concentration of hazardous chemicals is calculated using a steady-state model. Specifically, a steady-state Gaussian model or a modified steady-state Gaussian model may be used depending on the specific circumstances. Considering the conservatism of the assessment, the axial concentration is generally taken. The atmospheric diffusion concentration of hazardous chemicals can be calculated manually, using mathematical software, or using existing calculation software packages. The steady-state Gaussian model is currently a widely used model for calculating the atmospheric diffusion of pollutants. In this embodiment, the ALOHA software released by the U.S. Environmental Protection Agency is used for analysis.

[0077] According to the limits published by the National Institute for Occupational Safety and Health (NIOSH), the IDLH limit for HF is 30 ppm. According to the Acute Exposure Guideline Levels (AEGLs) published by the U.S. Environmental Protection Agency, the concentration of HF at the toxic endpoint after 60 minutes of exposure is 1 ppm.

[0078] In one specific embodiment, the facility site boundary radius is 0.5 km.

[0079] Based on the IDLH limit of HF, the IDLH concentration point radius under different atmospheric stability conditions can be obtained when the leakage location is a small hole, a medium hole, or a large hole. That is, the IDLH concentration point radius under different leakage scenarios and different atmospheric diffusion conditions, as shown in Table 2.

[0080] Similarly, based on the concentration value of the toxic endpoint of HF, the toxic endpoint radius under different atmospheric stability conditions can be obtained when the leakage location is a small hole, a medium hole, or a large hole, i.e. the toxic endpoint radius under different leakage scenarios and different atmospheric diffusion conditions, as shown in Table 3.

[0081] Table 2. Radius (m) of IDLH concentration points under different leakage scenarios and atmospheric stability conditions

[0082]

[0083] Table 3. Toxicity endpoint radius (km) under different leakage scenarios and atmospheric stability conditions

[0084]

[0085] S3. Assess environmental risk areas;

[0086] Using the release point of the hazardous chemical substance as the center, assess whether the radius of the toxic endpoint is greater than the radius of the plant site boundary. If the radius of the toxic endpoint is not greater than the radius of the plant site boundary, i.e., the toxic endpoint is within the plant site boundary, then the environmental safety of the facility meets the requirements of national regulatory authorities. If the radius of the toxic endpoint is greater than the radius of the plant site boundary, i.e., the toxic endpoint is outside the plant site boundary, then the affected areas and extents of the low-concentration, medium-concentration, and high-concentration zones need to be further explained as follows:

[0087] S31. Low concentration zone: The distance between the low concentration zone and the center is greater than the radius of the toxic endpoint, and the atmospheric concentration of the hazardous chemical substance in the low concentration zone is lower than the concentration value of the hazardous chemical substance at the toxic endpoint.

[0088] S32. Medium Concentration Zone: An area that may be affected by hazardous chemicals but will not endanger individual life safety; the distance between the medium concentration zone and the center is less than the radius of the toxic endpoint but greater than the radius of the IDLH concentration point. Within the medium concentration zone, the atmospheric concentration of the hazardous chemical is greater than the concentration value of the hazardous chemical at the toxic endpoint but less than the IDLH concentration limit of the hazardous chemical.

[0089] S33. High Concentration Area: An area that may endanger individual lives; the distance between the high concentration area and the center is less than the radius of the IDLH concentration point, and in the high concentration area, the atmospheric concentration of the hazardous chemical substance exceeds the IDLH concentration limit. The individual environmental risk value for the public in the high concentration area should be calculated based on the concentrations at each residential point outside the plant site boundary, and it should be explained whether the individual environmental risk value meets the requirements of the national regulatory authorities for individual risk.

[0090] Specifically, when comparing the radius of the IDLH concentration point with the radius of the plant site boundary, two methods can be used: the first method is to directly observe the data in the table, and the second method is to divide the radius of the IDLH concentration point by the radius of the plant site boundary. Through this comparison, the atmospheric diffusion conditions and leakage scenarios that significantly influence the atmospheric diffusion concentration of hazardous chemicals in a leak accident can be obtained.

[0091] In this embodiment, the second method is used to obtain the following table 4, which shows a comparison of radii under different leakage scenarios and different atmospheric stability.

[0092] Table 4. Comparison of radii under different leakage scenarios and atmospheric stability conditions.

[0093]

[0094] Table 4 directly shows the relative size relationship between the radius of the high concentration area and the radius of the plant site boundary; while the atmospheric diffusion conditions that have a greater impact on the atmospheric diffusion concentration of hazardous chemicals in a leak accident are: Class F stability and wind speed of 1.5 m / s.

[0095] Table 3 shows the calculated toxic endpoint radii for different leakage scenarios and atmospheric stability conditions. It can be seen that in the case of a large-hole leak, the radius of the low-concentration zone exceeds 10 km; while in the case of a medium-hole leak, the radius of the medium-concentration zone also exceeds 10 km under atmospheric diffusion conditions of Class F stability and 1.5 m / s. This demonstrates that the influence radius of the leaked hazardous chemicals is very large under these two types of leak scenarios.

[0096] S4. Analyze and quantify the risks;

[0097] Quantitatively calculate the individual environmental risk values ​​of the public in each residential area in the high-concentration zone, and analyze and explain whether the individual environmental risk values ​​of the public meet the requirements of the national regulatory authorities for individual risk.

[0098] The quantitative calculation of risk in step S4 includes the following steps:

[0099] S41. Calculate the individual mortality risk for each settlement within the high-concentration area;

[0100] The formula for calculating individual mortality risk is:

[0101]

[0102] In the formula:

[0103] P i Let be the probability of an individual in the public dying acutely from inhaling a hazardous chemical substance in the i-th leakage scenario;

[0104] erf is the error function. ;

[0105] Y is an intermediate quantity, and the formula for calculating Y is Y = a + b·ln(C n ·t e ); where C is the concentration, in ppm; t e The exposure time to this concentration is expressed in minutes, and the calculation takes the time of release of the hazardous chemical substance; a, b, and n are the toxicity constants of the hazardous chemical substance, which are taken as -26.4, 3.35, and 1 respectively.

[0106] S42. Calculate the individual risk value for the public in each leakage scenario;

[0107] The risk value for the individual public under certain atmospheric diffusion conditions in the i-th leakage scenario (calculation point) is calculated using the following formula:

[0108] ΔIR M,u,i =f i ×P M ×P u ×P i

[0109] In the formula:

[0110] ΔIR M,u,i The risk to the public in the i-th leakage scenario under certain atmospheric diffusion conditions;

[0111] f i Let be the annual failure probability of the i-th leakage scenario;

[0112] P M ×P uThe joint frequency of atmospheric stability M and wind speed u at a certain wind speed is called the three-dimensional joint frequency of the atmosphere (the three-dimensional joint frequency of the atmosphere refers to the joint frequency of atmospheric wind speed, atmospheric wind direction and atmospheric stability).

[0113] P i Let be the probability of an individual in the public dying acutely from inhaling a hazardous chemical substance in the i-th leakage scenario.

[0114] S43. Calculate the individual environmental risk value (IR) for each residential area.

[0115] The individual public environmental risk value (IR) for each residential area is calculated using the following formula:

[0116] IR=Σ i ×Σ M ×Σ u ΔIR M,u,i

[0117] In the formula:

[0118] i represents the i-th leakage scenario;

[0119] M represents atmospheric stability;

[0120] u represents wind speed;

[0121] ΔIR M,u,i Let be the risk to the general public under certain atmospheric diffusion conditions in the i-th leakage scenario.

[0122] This allows us to obtain the environmental risk value for acute death caused by inhalation of hazardous chemicals by an individual in each residential area under all the above-mentioned leakage scenarios and atmospheric diffusion conditions.

[0123] The calculated individual environmental risk value (IR) for each residential area is compared with 1×10. -6 Compare with the annual rate (in accordance with the relevant requirements of the "Interim Provisions on the Supervision and Management of Major Hazard Installations of Hazardous Chemicals" (Order No. 40 of the State Administration of Work Safety), if IR ≥ 1×10 -6 / year, indicating that the environmental risk value of the settlement is higher than this risk level, then the environmental risk of the settlement is unacceptable; if IR < 1×10 -6 The value per year indicates that the environmental risk level of the settlement is lower than the specified risk level, and therefore the environmental risk level of the settlement is acceptable.

[0124] In a specific embodiment, it is assumed that there are four residential areas A, B, C and D around the facility, and the distribution of each residential area is shown in Table 5 below.

[0125] Table 5. Distribution of residential areas around the facility

[0126]

[0127] The locations of the four residential sites A, B, C, and D are compared with the radii of the high-concentration zone. Then, according to the calculation formula in step S4, the environmental risk values ​​of each leakage scenario under different atmospheric diffusion conditions are calculated. The wind frequency data of the four residential sites A, B, C, and D under different atmospheric diffusion conditions are shown in Table 6 below, and the calculated environmental risk values ​​of the four residential sites A, B, C, and D are shown in Table 7 below.

[0128] Table 6. Joint three-dimensional atmospheric frequencies (%) of four settlements A, B, C, and D

[0129]

[0130] Table 7. Individual Environmental Risk Values ​​for Residential Sites A, B, C, and D

[0131]

[0132] In Table 7, " / " indicates that the concentration of hazardous chemicals at the residential site is below the IDLH concentration limit under this type of leakage scenario and atmospheric diffusion conditions, and is not included in the calculation of environmental risk value.

[0133] By summing the environmental risk values ​​of a residential area under all leakage scenarios and corresponding atmospheric diffusion conditions, the individual environmental risk value of the public at that residential area can be obtained.

[0134] As can be seen from the calculation results in Table 7, the residential area with the highest individual environmental risk value is D, which has an individual environmental risk value of 5.76 × 10⁻⁶. -7 / year, lower than the 1×10 required by national regulatory authorities -6 The per-year figure indicates that the environmental risk to the public from such hazardous chemical spills is acceptable.

[0135] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities, characterized in that, Includes the following steps: S1. Analyze the leakage scenarios of hazardous chemicals and estimate the leakage source terms; The analysis of the leakage scenarios considers three leakage locations of the feeding container: top, middle, and bottom. Each leakage location includes three leakage scenarios with different orifice diameters: small orifice leakage, medium orifice leakage, and large orifice leakage. The leakage source term is the leakage rate of each leakage scenario. S2. Calculate the radius of influence of the leaked hazardous chemical substance; The radius of influence includes the radius of the IDLH concentration point and the radius of the toxicity endpoint. The IDLH concentration point is the concentration point at which the atmospheric dispersion concentration of a hazardous chemical substance reaches the IDLH limit; based on the IDLH limit of the hazardous chemical substance, the radius of the IDLH concentration point is obtained under different leakage scenarios and different atmospheric diffusion conditions. The toxic endpoint is the concentration point at which a hazardous chemical substance will not cause irreversible effects on individuals in the public; based on the concentration value of the toxic endpoint of a hazardous chemical substance, the radius of the toxic endpoint is obtained under different leakage scenarios and different atmospheric diffusion conditions. S3. Assess environmental risk areas; If the radius of the toxic endpoint is not greater than the radius of the plant site boundary, the environmental safety of the facility meets the requirements of the national regulatory authorities; if the radius of the toxic endpoint is greater than the radius of the plant site boundary, the affected areas and ranges of the low-concentration zone, medium-concentration zone, and high-concentration zone should be further described; taking the release point of the hazardous chemical substance as the center, the distance between the low-concentration zone and the center is greater than the radius of the toxic endpoint; the distance between the medium-concentration zone and the center is less than the radius of the toxic endpoint but greater than the radius of the IDLH concentration point; the distance between the high-concentration zone and the center is less than the radius of the IDLH concentration point. S4. Analyze and quantitatively calculate the risks; Quantitatively calculate the individual environmental risk values ​​of the public in each residential area in the high-concentration zone, and analyze and explain whether the individual environmental risk values ​​of the public meet the requirements of the national regulatory authorities for individual risk. In step S4, the quantitative calculation of the risk includes the following steps: S41. Calculate the individual mortality risk of individuals in each residential area within the high-concentration zone in the i-th leakage scenario; The formula for calculating the individual mortality risk is as follows: In the formula: P i Let be the probability of an individual in the public dying acutely from inhaling a hazardous chemical substance in the i-th leakage scenario; erf is the error function. ; Y is an intermediate quantity, and the formula for calculating Y is Y = a + b·ln(C n ·t e ); where C is the concentration, in ppm; t e The exposure time to this concentration is expressed in minutes, and the calculation takes the time of release of the hazardous chemical substance; a, b, and n are the toxicity constants of the hazardous chemical substance. S42. Calculate the individual risk value for the public in each leakage scenario; The risk value for the individual public under certain atmospheric diffusion conditions in the i-th leakage scenario is calculated using the following formula: ΔIR M,u,i =f i ×P M ×P u ×P i In the formula: ΔIR M,u,i The risk to the public in the i-th leakage scenario under certain atmospheric diffusion conditions; f i Let be the annual failure probability of the i-th leakage scenario; P M ×P u The three-dimensional joint frequency of atmospheric stability M and wind speed u under a certain wind direction; P i Let be the probability of an individual in the public dying acutely from inhaling a hazardous chemical substance in the i-th leakage scenario; S43. Calculate the individual environmental risk value (IR) for each residential area; The individual public environmental risk value (IR) for each residential area is calculated using the following formula: IR=Σ i ×S M ×S u ΔIR M,u,i In the formula: i represents the i-th leakage scenario; M represents atmospheric stability; u represents wind speed; ΔIR M,u,i Let i represent the risk to the public and individuals in the i-th leakage scenario under certain atmospheric diffusion conditions.

2. The method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities according to claim 1, characterized in that, The diameter of the small hole leakage is 1 mm, the diameter of the medium hole leakage is 10 mm, and the diameter of the large hole leakage is 50 mm.

3. The method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities according to claim 1, characterized in that, When estimating the leakage source, the highest pressure and highest temperature set by the process in which the feeding container is located are used for calculation and analysis.

4. The method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities according to claim 1, characterized in that, When calculating the radius of influence, the atmospheric stability categories that need to be considered in calculating the atmospheric diffusion concentration of hazardous chemicals include: Category B, Category D, Category E, and Category F.

5. The method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities according to claim 4, characterized in that, When calculating the radius of influence, a steady-state model is used to calculate the atmospheric diffusion concentration of hazardous chemicals.

6. The method for assessing the atmospheric toxicity risk of uranium processing and fuel manufacturing facilities according to claim 1, characterized in that, The calculated individual environmental risk value (IR) for each residential area is compared with 1×10. -6 Comparing per year, if the individual public environmental risk value (IR) of a residential area is ≥1×10⁻⁶, then... -6 If the environmental risk of the settlement is less than / year, then the environmental risk of the settlement is unacceptable. If the individual environmental risk value (IR) of a residential area is less than 1×10 -6 If the environmental risk level of the settlement is within a certain range per year, then the environmental risk level of the settlement is acceptable.

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