Method for assessing the inhalation pathway probability of a radionuclide-contaminated site

Abstract

The present application relates to a kind of radionuclide contaminated site inhalation pathway probability risk assessment method.The radionuclide contaminated site inhalation pathway probability risk assessment method provided by the present application, by investigating the method model of foreign radioactive contaminated site risk assessment, after comparative analysis, select to use the wide range, maturity high deterministic mode, then select the inhalation pathway of greater influence, study air / soil concentration ratio, area correction coefficient, covering and depth correction coefficient, residence coefficient and air annual intake amount etc.The probability density distribution function of the related parameters of the environmental transfer coefficient of inhalation pathway is obtained, and the probability distribution function of the environmental transfer coefficient of inhalation pathway is obtained, and the dose value based on probability distribution of inhalation pathway is obtained, and by comparing with the dose specified in the relevant standard, the risk assessment conclusion of the inhalation pathway of radioactive contaminated site is obtained, and the foundation for public dose assessment is laid.

Description

Technical Field

[0001] This invention belongs to the field of radiation protection risk assessment technology, specifically relating to a method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites. Background Technology

[0002] In recent years, with the rapid development of my country's nuclear industry and the successive decommissioning of nuclear facilities, a number of sites contaminated by radioactive nuclides and sites left behind after the decommissioning of nuclear facilities have emerged. The redevelopment and utilization of such sites poses significant environmental risks, endangering public health, ecological environment safety and social stability, which has aroused great concern from the whole society and government departments.

[0003] Currently, the assessment model for radioactive nuclide contaminated sites in China is a standard general model. This general model is based on the premise that the site medium is uniform and the relevant parameters for risk assessment are fixed. However, it lacks consideration of the uncertainty of the parameter values ​​and ignores the impact of parameter uncertainty on risk assessment, resulting in conservative assessment results that fail to accurately reflect the current status of the contamination impact. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a probabilistic risk assessment method for the inhalation pathways of radioactive nuclide-contaminated sites. Based on a deterministic risk assessment model for radioactive contaminated sites, the method selects the inhalation pathways that contribute significantly to public dose. By studying the probability distribution of the model's input parameters, the method obtains the probability density distribution function of the environmental transfer coefficient of the inhalation pathway and calculates the dose generated per unit concentration of radionuclide in the soil of the radioactive contaminated site, thereby obtaining the risk assessment conclusion for the inhalation pathways of radioactive contaminated sites.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites, comprising the following steps:

[0006] S1. Establish a dose assessment model;

[0007] S2. Investigate and statistically analyze relevant parameters of the environmental transfer coefficient of the inhalation route;

[0008] S3. The probability distribution function of relevant parameters of the environmental transfer coefficient of the inhalation route;

[0009] S4. Obtain the dose produced by a unit concentration of radionuclides in the soil of a radiocontaminated site;

[0010] S5. Obtain the risk assessment conclusion of the inhalation route from radioactive contaminated sites.

[0011] Furthermore, the dose assessment model is a deterministic risk assessment model.

[0012] Furthermore, the relevant parameters of the environmental transfer coefficient of the inhalation pathway include: air / soil concentration ratio, area correction factor, cover and depth correction factor, residence factor, and annual air intake.

[0013] Furthermore, in step S2, the values ​​of relevant parameters of the environmental transfer coefficient of the inhalation pathway are given.

[0014] Furthermore, step S3 includes the following two steps:

[0015] S31. Membership function of triangular fuzzy number of relevant parameters for determining the environmental transfer coefficient of inhalation route for age-group populations;

[0016] S32. The probability density distribution function of the triangular fuzzy number of relevant parameters for establishing the environmental transfer coefficient of the inhalation route for different age groups.

[0017] Furthermore, the membership function of the triangular fuzzy number, a relevant parameter of the environmental transfer coefficient of the inhalation pathway, is expressed by equation (1):

[0018]

[0019] Where μ(x) is the membership function of the triangular fuzzy number of the environmental transfer coefficient of the inhalation pathway, and x is the relevant parameter of the environmental transfer coefficient of the inhalation pathway; a, b, and c are the minimum, expected, and maximum values ​​of the relevant parameter of the environmental transfer coefficient of the inhalation pathway for the corresponding age group population, respectively.

[0020] Furthermore, the probability density distribution function of the triangular fuzzy number, a relevant parameter of the environmental transfer coefficient of the inhalation pathway, is expressed by equation (2):

[0021]

[0022] Among them, f A (x) is the probability density distribution function of the triangular fuzzy number A, which is the relevant parameter of the environmental transfer coefficient of the inhalation route. x is the relevant parameter of the environmental transfer coefficient of the inhalation route; a, b, and c are the minimum, expected, and maximum values ​​of the relevant parameter of the environmental transfer coefficient of the inhalation route for the corresponding age group, respectively.

[0023] Furthermore, step S4 includes the following two steps:

[0024] S41. The probability density distribution function of the environmental transfer coefficient of the inhalation route for different age groups;

[0025] S42. Calculate the dose produced by a unit concentration of radionuclides in the soil of radiocontaminated sites for different age groups.

[0026] Furthermore, the probability density distribution function of the environmental transfer coefficient of the inhalation pathway is expressed by equation (3):

[0027] ETF i =ASR×FA×FCD(t)×FO×FI (3)

[0028] Among them, ETF i —Probability density distribution function of environmental transfer coefficient via inhalation route, g / a;

[0029] ASR—Air / Soil Concentration Ratio, g / m³ 3 ;

[0030] FA—Area Correction Factor;

[0031] FCD(t) — Coverage and depth correction factor;

[0032] FO—Detention coefficient;

[0033] FI—Annual air intake, m 3 / a.

[0034] Furthermore, the dose produced by a unit concentration of radionuclides in the soil of the radiocontaminated site is expressed by formula (4):

[0035] DSR i =DCF i ×ETF i ×SF i (4)

[0036] Among them, DSR i —The dose produced by a unit concentration of radionuclide i in soil, g / a;

[0037] DCF i — Dosage conversion factor;

[0038] ETF i —Probability density distribution function of environmental transfer coefficient via inhalation route, g / a;

[0039] SF i —Source characteristic correction factor.

[0040] The beneficial effects of this invention are as follows: Using the probabilistic risk assessment method for radioactive nuclide-contaminated sites provided by this invention, after researching and comparing foreign methods and models for risk assessment of radioactive contaminated sites, a deterministic model with wide application and high maturity is selected. Then, the most influential inhalation pathways are selected, and the probability density distribution functions of relevant parameters of the environmental transfer coefficients of inhalation pathways, such as the air / soil concentration ratio (ASR), area correction factor (FA), coverage and depth correction factor (FCD(t)), residence factor (FO), and annual air intake (FI), are studied. The probability distribution function of the environmental transfer coefficient of the inhalation pathway is then obtained, and the dose value of the inhalation pathway based on the probability distribution is calculated. Finally, by comparing the dose with the dose specified in relevant standards, the risk assessment conclusion of the radioactive contaminated site inhalation pathway is obtained. This invention, by conducting research on a probabilistic risk assessment method, supplements and improves the deterministic method, can truly reflect the impact of parameter changes on the risk assessment results, realize the uncertainty analysis of input parameters, and thus obtain the risk assessment results, laying the foundation for the assessment of the dose received by the public. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the probabilistic risk assessment method for the inhalation pathway of radioactive nuclide contaminated sites provided by the present invention. Detailed Implementation

[0042] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0043] like Figure 1 As shown in the figure, the present invention provides a method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites, the method comprising the following steps:

[0044] S1. Establish a dose assessment model;

[0045] In this implementation, by surveying the risk assessment methods and models for radioactive contaminated sites in countries such as the United States, France, and Japan, as well as the International Atomic Energy Agency (IAEA), and through comparative analysis, we selected the most widely used and mature models and methods. Then, considering the characteristics of radioactive contaminated sites in my country, we selected a deterministic risk assessment model (which is also the current radioactive contaminated site assessment model used in China).

[0046] S2. Investigate and statistically analyze relevant parameters of the environmental transfer coefficient of the inhalation route;

[0047] In this embodiment, by surveying empirical values, literature, and historical data on the environmental transfer coefficient of the inhalation route both domestically and internationally, and combining them with actual measurement data from radioactive contaminated sites in China, the values ​​of the relevant parameters of the environmental transfer coefficient of the inhalation route in the risk assessment of the inhalation route are given after sorting, summarizing, and statistical analysis. The values ​​of the relevant parameters of the environmental transfer coefficient of the inhalation route include the minimum, expected, and maximum values ​​of the relevant parameters of the environmental transfer coefficient of the inhalation route for each age group, as shown in Table 1 below.

[0048] The relevant parameters of the environmental transfer coefficient of the inhalation pathway include: air / soil concentration ratio (ASR), area correction factor (FA), cover and depth correction factor (FCD(t)), residence factor (FO), and annual air intake (FI).

[0049] Table 1. Values ​​of relevant parameters for the environmental transfer coefficient of the inhalation route in the risk assessment.

[0050]

[0051] S3. The probability distribution function of relevant parameters of the environmental transfer coefficient of the inhalation route;

[0052] In this embodiment, fuzzy distribution is used to study the probability distribution function of the relevant parameters of the environmental transfer coefficient of the inhalation pathway. Fuzzy distribution mainly includes various forms such as triangular distribution, trapezoidal distribution, rectangular distribution, normal distribution, and Cauchy distribution. Since the triangular distribution is easier to perform algebraic operations and facilitates membership function processing, this embodiment uses triangular fuzzy numbers to represent the membership degree of the relevant parameters of the environmental transfer coefficient of the inhalation pathway.

[0053] Step S3 includes the following two steps:

[0054] S31. Membership function of triangular fuzzy number of relevant parameters for determining the environmental transfer coefficient of inhalation route for age-group populations;

[0055] The definition of a triangular fuzzy number is as follows: Let A be a triangular fuzzy number in the real number field R, and define a membership function μ(x), x∈R, the membership function μ(x) is expressed by the following equation (1):

[0056]

[0057] Where μ(x) is the membership function of the triangular fuzzy number of the relevant parameters of the environmental transfer coefficient of the inhalation pathway, and x is the relevant parameter of the environmental transfer coefficient of the inhalation pathway; A is the triangular fuzzy number of the relevant parameters of the environmental transfer coefficient of the inhalation pathway, denoted as A = (a, b, c); a, b, and c are the minimum, expected, and maximum values ​​of the relevant parameters of the environmental transfer coefficient of the inhalation pathway for the corresponding age group obtained in step S2, respectively. When a = b = c, A is a definite real number.

[0058] S32. The probability density distribution function of the triangular fuzzy number of relevant parameters for establishing the environmental transfer coefficient of the inhalation route for different age groups;

[0059] According to equation (1), by dividing the membership function μ(x) by the area (ca) / 2 enclosed by the membership function μ(x) and the x-axis, we finally obtain the probability density distribution function f of the triangular fuzzy number A, a related parameter of the environmental transfer coefficient of the inhalation pathway, as shown in equation (2). A (x):

[0060]

[0061] Among them, f A (x) is the probability density distribution function of the triangular fuzzy number A, which is the relevant parameter of the environmental transfer coefficient of the inhalation pathway. x is the relevant parameter of the environmental transfer coefficient of the inhalation pathway; a, b, and c are the minimum, expected, and maximum values ​​of the relevant parameters of the environmental transfer coefficient of the inhalation pathway for each age group, respectively.

[0062] S4. Obtain the dose produced by a unit concentration of radionuclides in the soil of a radiocontaminated site;

[0063] In this embodiment, step S4 includes the following two steps:

[0064] S41. The probability density distribution function of the environmental transfer coefficient of the inhalation route for different age groups;

[0065] Based on the probability density distribution function f of the relevant parameters of the environmental transfer coefficient of the inhalation pathway for the age group population obtained in step S32. A (x), combined with equation (3), the Monte Carlo method is used to simulate and generate random numbers for the relevant parameters of the environmental transfer coefficient of each inhalation route. The calculations are considered for 10,000 times, 100,000 times and 1,000,000 times respectively. Comparative analysis reduces errors, and the probability density distribution function of the environmental transfer coefficient of the inhalation route is obtained for people of different age groups.

[0066] ETF i =ASR×FA×FCD(t)×FO×FI (3)

[0067] Among them, ETFi —Probability density distribution function of environmental transfer coefficient via inhalation, g / a, where the subscript i represents radionuclide i;

[0068] ASR—Air / Soil Concentration Ratio, g / m³ 3 ;

[0069] FA—Area Correction Factor;

[0070] FCD(t) — Coverage and depth correction factor;

[0071] FO—Detention coefficient;

[0072] FI—Annual air intake, m 3 / a.

[0073] S42. Calculate the dose produced by a unit concentration of radionuclides in the soil of a radiocontaminated site for different age groups.

[0074] In this embodiment, based on the probability density distribution function of the environmental transfer coefficient of the inhalation pathway obtained by the age group in step S41, and combined with equation (4), the dose (DSR) generated by a unit concentration of radionuclide i in the soil of the radiocontaminated site is calculated for the age group. i ):

[0075] DSR i =DCF i ×ETF i ×SF i (4)

[0076] Among them, DSR i —The dose produced by a unit concentration of radionuclide i in soil, g / a;

[0077] DCF i — Dosage conversion factor;

[0078] ETF i —Probability density distribution function of environmental transfer coefficient via inhalation route, g / a;

[0079] SF i —Source characteristic correction factor.

[0080] S5. Obtain the risk assessment conclusion of the inhalation route from radioactive contaminated sites.

[0081] The dose generated by a unit concentration of radionuclides in the soil of the radiocontaminated site calculated in step S4 is compared with the dose specified in relevant standards to obtain the risk assessment conclusion of the inhalation route of the radiocontaminated site.

[0082] The probabilistic risk assessment method for inhalation pathways at radionuclide-contaminated sites provided in this invention, through research on foreign methods and models for risk assessment of radionuclide-contaminated sites, and after comparative analysis, selects a deterministic model with wide application and high maturity, and chooses the inhalation pathway with significant impact. It studies the probability density distribution functions of relevant parameters such as air / soil concentration ratio (ASR), area correction factor (FA), coverage and depth correction factor (FCD(t)), residence factor (FO), and annual air intake (FI), thereby obtaining the probability distribution function of the environmental transfer coefficient of the inhalation pathway. Finally, it calculates the dose value of the inhalation pathway based on the probability distribution, and then compares it with the dose specified in relevant standards to obtain the risk assessment conclusion of the inhalation pathway at radionuclide-contaminated sites, laying the foundation for the dose assessment of the public.

[0083] By conducting research on risk assessment methods based on probability theory, the inventors have supplemented and improved deterministic methods, which can truly reflect the impact of parameter changes on risk assessment results, realize uncertainty analysis of input parameters, and thus obtain risk assessment results.

[0084] The methods described in this invention are not limited to the specific embodiments described above. The embodiments described are merely illustrative examples of this invention, and the invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of this invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of this invention.

Claims

1. A method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites, characterized in that: The method includes the following steps: S1. Establish a dose assessment model; S2. Investigate and statistically analyze relevant parameters of the environmental transfer coefficient of the inhalation route; The relevant parameters for the environmental transfer coefficient of the inhalation pathway include: air / soil concentration ratio, area correction factor, cover and depth correction factor, residence factor, and annual air intake. S3. The probability distribution function of relevant parameters of the environmental transfer coefficient of the inhalation route; Step S3 includes the following two steps: S31. Membership function of triangular fuzzy number of relevant parameters for determining the environmental transfer coefficient of inhalation route for age-group populations; S32. The probability density distribution function of the triangular fuzzy number of relevant parameters for establishing the environmental transfer coefficient of the inhalation route for different age groups; S4. Obtain the dose produced by a unit concentration of radionuclides in the soil of a radiocontaminated site; Step S4 includes the following two steps: S41. The probability density distribution function of the environmental transfer coefficient of the inhalation route for different age groups; S42. Calculate the dose produced by a unit concentration of radionuclides in the soil of a radiocontaminated site for different age groups. S5. Obtain the risk assessment conclusion of the inhalation route from radioactive contaminated sites.

2. The method for assessing the probability risk of inhalation pathways from radionuclide-contaminated sites according to claim 1, characterized in that: The dose assessment model is a deterministic risk assessment model.

3. The method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites according to claim 1, characterized in that: In step S2, the values ​​of relevant parameters of the environmental transfer coefficient of the inhalation pathway are given.

4. The method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites according to claim 1, characterized in that: The membership function of the triangular fuzzy number, a relevant parameter of the environmental transfer coefficient of the inhalation route, is expressed by equation (1): Where μ(x) is the membership function of the triangular fuzzy number of the environmental transfer coefficient of the inhalation pathway, and x is the relevant parameter of the environmental transfer coefficient of the inhalation pathway; a, b, and c are the minimum, expected, and maximum values ​​of the relevant parameter of the environmental transfer coefficient of the inhalation pathway for the corresponding age group population, respectively.

5. The method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites according to claim 1, characterized in that: The probability density distribution function of the triangular fuzzy number, a relevant parameter of the environmental transfer coefficient of the inhalation route, is expressed by equation (2): Among them, f A (x) is the probability density distribution function of the triangular fuzzy number of the relevant parameters of the environmental transfer coefficient of the inhalation pathway, where x is the relevant parameter of the environmental transfer coefficient of the inhalation pathway; a, b, and c are the minimum, expected, and maximum values ​​of the relevant parameters of the environmental transfer coefficient of the inhalation pathway for each age group, respectively.

6. The method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites according to claim 1, characterized in that: The probability density distribution function of the environmental transfer coefficient of the inhalation route is expressed by equation (3): ETF i =ASR×FA×FCD(t)×FO×FI(3) Among them, ETF i —Probability density distribution function of environmental transfer coefficient via inhalation route, g / a; ASR—Air / Soil Concentration Ratio, g / m³ 3 ; FA—Area Correction Factor; FCD(t) — Coverage and depth correction factor; FO—Detention coefficient; FI—Annual air intake, m 3 / a.

7. The method for assessing the probability risk of inhalation pathways from radioactive nuclide-contaminated sites according to claim 6, characterized in that: The dose produced by a unit concentration of radionuclides in the soil of the radiocontaminated site is expressed by formula (4): DSR i =DCF i ×ETF i ×SF i (4) Among them, DSR i —The dose produced by a unit concentration of radionuclide i in soil, g / a; DCF i — Dosage conversion factor; ETF i —Probability density distribution function of environmental transfer coefficient via inhalation route, g / a; SF i —Source characteristic correction factor.

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