A method, system, medium and equipment for risk assessment of substation fire residues

Abstract

The present invention relates to a method for assessing the risk of fire residues in a substation, comprising the following steps: determining an exposure medium for fire residues; determining an exposure route for fire residues; calculating the concentration of fire residues in a first exposure medium; setting a distribution ratio of fire residues entering other exposure mediums through the first exposure medium; calculating the concentration of fire residues in other exposure mediums based on the distribution ratio and the concentration of fire residues in the first exposure medium; calculating the average daily exposure amount of fire residues in different exposure routes based on the fire residue concentrations in different exposure mediums; and calculating the carcinogenic risk and non-carcinogenic risk of fire residues in different exposure routes based on the average daily exposure amount of fire residues.

Description

Technical Field

[0001] The present invention relates to a method, system, medium and equipment for risk assessment of fire residues in a transformer substation, belonging to the field of risk assessment. Background Art

[0002] When a fire, explosion, or other accident occurs in a substation, thermal radiation is generated, and a large amount of thick smoke and exhaust gas diffuses into the surrounding air, affecting the ambient air quality. Firefighting produces a large amount of firefighting wastewater, which may enter the rainwater pipes within the substation area. If the rainwater outlet is not blocked, it may be discharged into the water area outside the station, affecting the surface water quality. Fire and explosion accidents cause the main control transformer oil to leak, and if the enclosure is not timely, it will also enter the external environment. Therefore, pollutants generated by fire accidents (such as mineral oil, heavy metals, and PAHs) can enter the surrounding air, soil, water bodies, crops, and other exposure media, affecting or endangering the ecosystem and the health of sensitive people in the surrounding area. Therefore, a risk assessment method for substation fire residues is needed. Summary of the Invention

[0003] In order to overcome the problems existing in the prior art, the present invention designs a substation fire residue risk assessment method, system, medium and equipment. According to the concentration of fire residues in different exposure media, the average daily exposure to fire residues is calculated, thereby obtaining the carcinogenic risk and non-carcinogenic risk of fire residues in different exposure pathways, and realizing the human health risk assessment of residues generated by substation electrical equipment fires.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for risk assessment of fire residues in a substation, comprising the following steps:

[0006] Identify several exposure media for fire residues;

[0007] Identify several exposure pathways for fire debris;

[0008] calculating a concentration of fire residues in a first exposure medium, where the first exposure medium is the exposure medium that the fire residues first enter among the plurality of exposure pathways;

[0009] Setting a distribution ratio of the fire residues from the first exposure medium to the other exposure mediums; and calculating the fire residue concentrations in the other exposure mediums based on the distribution ratio and the fire residue concentration in the first exposure medium.

[0010] Based on the concentration of fire residues in different exposure media, the average daily exposure to fire residues in different exposure routes is calculated; based on the average daily exposure to fire residues, the carcinogenic risk and non-carcinogenic risk of fire residues in different exposure routes are calculated.

[0011] Furthermore, it also includes:

[0012] Fit the functional relationship between the distance from the first exposure medium to the fire source and the concentration of fire residues in the first exposure medium, and calculate the concentration of fire residues in the first exposure medium at different distances;

[0013] Calculate the carcinogenic risk of fire residues at different distances and different exposure pathways based on the fire residue concentrations in the first exposure medium at the different distances;

[0014] The total carcinogenic risk is obtained by adding up the carcinogenic risks of fire residues at the same distance and different exposure pathways;

[0015] According to the total carcinogenic risk, the fire-affected area is divided into the risk acceptable area, the potential carcinogenic risk area and the carcinogenic risk area.

[0016] Furthermore, it also includes:

[0017] At the critical point between the designated carcinogenic risk zone and the potential carcinogenic risk zone, the total benzo[a]pyrene toxic equivalent concentration of fire residues in each exposure medium was calculated.

[0018] Furthermore, the functional relationship between the distance between the first exposure medium and the fire source and the concentration of the fire residue in the first exposure medium is specifically:

[0019] Within the first distance from the fire source, the fire residue concentration in the first exposure medium is obtained through on-site measurement; outside the second distance from the fire source, the fire plume deposition flux is obtained and converted into the fire residue concentration in the first exposure medium; within the second distance outside the first distance from the fire source, the fire residue concentration in the first exposure medium is calculated by extrapolation or interpolation; based on the fire residue concentration in the first exposure medium, a nonlinear fitting is performed on the distance of the first exposure medium from the fire source and the fire residue concentration in the first exposure medium to obtain the functional relationship between the fire residue concentration in the first exposure medium and the distance.

[0020] Furthermore, the carcinogenic risk of fire residues under different exposure pathways is calculated using the formula:

[0021] CR n =ADD n ×SF n

[0022] Where, CR n Indicates the carcinogenic risk of fire residues to humans under the nth exposure route; ADD n SF represents the average daily exposure to fire residues under the nth exposure pathway; nFurthermore, the non-carcinogenic risk of fire residues under different exposure pathways is calculated using the formula:

[0023]

[0024] Where HI n Indicates the non-carcinogenic risk of fire residues to humans under the nth exposure route; ADD n RfD represents the average daily exposure to fire residues under the nth exposure pathway; n It represents the long-term ingestion reference dose of fire residues under the nth exposure mode.

[0025] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0026] This method calculates the average daily exposure to fire residues based on the concentration of fire residues in different exposure media, thereby determining the carcinogenic and non-carcinogenic risks of fire residues across different exposure pathways. This approach enables a human health risk assessment of residues generated by substation electrical equipment fires. Furthermore, by fitting a functional relationship between the distance of the first exposure medium from the fire source and the concentration of fire residues, the total carcinogenic risk of fire residues at different distances is determined. This allows for the classification of acceptable risk zones, potential carcinogenic risk zones, and carcinogenic risk zones, facilitating subsequent risk management. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a flow chart of the present invention;

[0028] Figure 2 This is a schematic diagram of the change of PAHs concentration-distance in soil;

[0029] Figure 3 This is a diagram showing the change in the total carcinogenic risk of PAHs in adults and children as a function of the distance from the fire source;

[0030] Figure 4 This is a diagram showing the change in the total carcinogenic risk of PAHs in adults and children as a function of the distance from the fire source, ignoring the food exposure pathway;

[0031] Figure 5 This is a schematic diagram of the change in the total non-carcinogenic risk of PAHs in adults / children as the distance from the fire source changes. DETAILED DESCRIPTION

[0032] The present invention will be described in more detail below with reference to the embodiments.

[0033] Example 1

[0034] like Figure 1 As shown, a method for risk assessment of fire residues in a substation includes the following steps:

[0035] In this embodiment, the fire source is a substation; the fire residues are polycyclic aromatic hydrocarbons (PAHs), which are compounds composed of two or more benzene rings arranged in a linear, angular or clustered shape.

[0036] The exposure media of PAHs were determined to include surface water, groundwater, soil, and food. It was assumed that PAHs first entered the soil and then entered other exposure media through the soil.

[0037] The exposure routes of PAHs include direct inhalation of soil, oral ingestion, skin contact with soil, ingestion of food, oral drinking of surface / groundwater, and direct skin contact with surface / groundwater.

[0038] Fitting the functional relationship between distance and soil PAHs concentration: Within a first distance from the substation, soil PAHs concentrations were obtained through field sampling. Outside the substation, fire plume deposition flux was measured and converted to soil PAHs concentrations using the CALPUFF model. Within the second distance from the substation, soil PAHs concentrations were determined using extrapolation and interpolation. The first distance was smaller than the second distance. Based on the soil fire residue concentrations obtained at different distances, a nonlinear fit was performed using the WRF-CALPUFF coupled model to determine the relationship between soil distance from the fire source and soil PAHs concentration. This relationship was then used to determine the functional relationship between soil PAHs concentration and distance around the substation under a pre-defined fire scenario. This functional relationship allowed the determination of soil PAHs concentrations at different distances.

[0039] Set the distribution ratio of PAHs into different exposure media (such as soil residues: food: groundwater: surface water), and calculate the concentration of PAHs in other exposure media based on the concentration and distribution ratio of PAHs in soil.

[0040] Based on the concentrations of PAHs in different exposure media, the average daily exposure to PAHs under different exposure pathways was calculated.

[0041] Based on the average daily exposure to PAHs, the carcinogenic risk and non-carcinogenic risk of PAHs under different exposure pathways are calculated using the formula:

[0042] CR n =ADD n ×SF n

[0043] Where, CR n ADD represents the carcinogenic risk of fire residues to humans under the nth exposure route, dimensionless; n represents the average daily exposure to fire residues under the nth exposure pathway; SF nCarcinogenic slope factor for fire residues under the nth exposure route, [mg / (kg·d)]-1.

[0044]

[0045] Where HI n ADD represents the non-carcinogenic risk of fire residues to humans under the nth exposure route, dimensionless; n RfD represents the average daily exposure to fire residues under the nth exposure pathway; n It represents the long-term reference dose of fire residues under the nth exposure mode, mg / (kg·d)

[0046] The total carcinogenic risk is obtained by adding up the carcinogenic risks of fire residues at the same distance and different exposure pathways;

[0047] Preset risk thresholds; based on the total carcinogenic risk and risk thresholds, the fire-affected area is divided into risk-acceptable areas, potential carcinogenic risk areas, and carcinogenic risk areas.

[0048] At the critical point between the carcinogenic risk zone and the potential carcinogenic risk zone, the total benzopyrene toxic equivalent concentration (ΣBaP eq ). Finally, ΣBaP in a single exposure medium eq The areas with the largest range or area among the areas above the national standard, carcinogenic risk areas and non-carcinogenic risk areas shall be regarded as the key risk control areas after the fire occurs; the risk acceptable areas (CR<10 -6 ) as a safe area in fire scenarios.

[0049] Example 2

[0050] Calculate the average daily exposure to fire residues under different exposure pathways:

[0051] 1. Calculate the average daily exposure through respiratory inhalation

[0052] Exposure to pollutants through the respiratory tract includes inhalation of pollutants from the atmosphere and inhalation of particulate and gaseous pollutants from the soil. Considering the relatively short duration of the fire and the influence of various meteorological factors, the high concentrations of PAHs produced in the atmosphere rapidly drop to near zero within a short period of time, ultimately entering the soil through sedimentation. Therefore, the risk to human health from exposure to PAHs produced in the air by the fire is not considered in this example. The average daily exposure to PAHs from contaminated soil through the respiratory tract is calculated as follows:

[0053]

[0054] ADD inh-soil——Exposure to PAHs from contaminated soil through inhalation, mg / (kg·d);

[0055] C s ——PAHs concentration in soil, mg / kg;

[0056] IR a ——The human body's breathing volume per hour, m 3 / h;

[0057] ET – daily exposure hours, h / d;

[0058] EF—exposure frequency, d / a;

[0059] ED – duration of exposure, a;

[0060] VF——the volatility level of PAHs in the environment (volatility factor), m 3 / kg

[0061] PEF - soil dust generation factor, m 3 / kg;

[0062] BW - body weight, kg;

[0063] AT——average exposure time, d.

[0064] 2. Calculate the average daily exposure through digestive tract intake

[0065] (A) Average daily exposure to PAHs from oral intake of contaminated food:

[0066]

[0067] ADD oral-food —Exposure to PAHs from oral intake of contaminated food (mainly vegetables grown on contaminated soil), in mg / (kg·d);

[0068] C f ——PAHs concentration in food, in mg / kg;

[0069] IR f ——Average daily food intake, kg / d. Since carrots are the main vegetable crops near the Dongyuan substation, China's annual carrot consumption is approximately 16.8 million tons. [110-111] , the average daily carrot intake of Chinese residents is calculated to be 0.033 kg / d. Assuming that children's intake is half of that of adults, the intake for children is calculated to be 0.022 kg / d, and for adults, it is calculated to be 0.044 kg / d.

[0070] C F——Conversion coefficient between wet mass and dry mass of vegetables

[112] .

[0071] (B) Daily exposure to PAHs through oral drinking of contaminated groundwater / surface water

[0072]

[0073] ADD oral-water ——Exposure to PAHs from oral drinking of contaminated groundwater / surface water, mg / (kg·d);

[0074] C w ——PAHs concentration in groundwater / surface water, mg / L

[0075] IR w ——Average daily intake volume of surface water / groundwater, L / d.

[0076] (C) Average daily exposure to PAHs from contaminated soil through oral ingestion

[0077]

[0078] ADD oral-soil ——Exposure to PAHs in contaminated soil through oral ingestion, mg / (kg·d);

[0079] IR s ——The mass of soil ingested by the human body every day, mg / d;

[0080] CF - mass conversion factor, 1×10 -6 kg / mg.

[0081] 3. Calculate the average daily exposure through skin contact

[0082] (A) Average daily exposure to PAHs in contaminated soil through direct skin contact:

[0083]

[0084] ADD dermal-soil ——Exposure amount of PAHs in contaminated soil by human skin, mg / (kg·d);

[0085] SA s ——Area of ​​human skin in contact with contaminated soil, cm 2 ;

[0086] AF——per cm 2 Skin adhesion soil mass, mg / cm 2 ;

[0087] ABSd ——Absorption efficiency factor of PAHs by skin contact, dimensionless.

[0088] (B) Daily exposure to PAHs in contaminated surface water / groundwater through direct skin contact

[0089]

[0090] ADD dermal-water ——Exposure amount of PAHs in human skin from direct contact with contaminated surface water / groundwater, mg / (kg·d);

[0091] SA w ——Surface area of ​​human skin in contact with contaminated surface water / groundwater, cm 2 ;

[0092] PC - permeability constant of PAHs to skin, cm / h;

[0093] CF w ——Volume conversion factor, 1×10 -3 L / cm 3 ;

[0094] ET w ——Average bathing time per person per day, h / d.

[0095] Example 3

[0096] 1. Fire scenario analysis:

[0097] The substation's insulating oil weighed 13.75 tons, 50% of it leaked and burned, with one fire incident and a duration of 2 hours. The prevailing wind direction was southwesterly at a speed of 3.2 m / s. The contaminated land use types were residential and agricultural (the primary vegetable grown was carrots). The fire affected a certain school district to the northeast. The sensitive populations were adults and children. Surface water was assumed to exist within 500 meters of the substation. After the fire, PAHs carried in the large amount of smoke and dust generated by the fire diffused and migrated through the atmosphere under the influence of meteorological factors, eventually settling into the soil. Vegetables continued to be grown on the untreated soil, transferring the pollutants to the vegetables. Furthermore, PAHs generated by firefighting wastewater, residual water, and water-soluble transformer oil smoke and residues that were not discharged into the sewer system entered nearby surface waters through surface runoff. Some pollutants seeped into groundwater through rainfall and other means, ultimately causing environmental contamination.

[0098] 2. Analysis of the diffusion law of PAHs in soil:

[0099] After a substation fire, soil PAHs concentrations vary with distance from the fire source. At close range, concentrations are significantly elevated due to multiple factors, including unburned debris, firefighting wastewater leakage, and smoke deposition. Models cannot accurately predict soil PAH concentrations under these conditions. Therefore, field measurements are used to ensure accurate results. At long distances, the primary contribution of fire to soil PAHs is smoke deposition. Therefore, the CALPUFF model is used to obtain smoke plume deposition flux output and convert it into long-distance soil PAH concentrations. Furthermore, soil PAH concentrations are missing at distances intermediate between the measured and model outputs. Extrapolation and interpolation methods are used to determine concentrations in the intermediate range. Finally, a curve of soil PAH concentrations varying with distance from the fire source is fitted based on the measured, interpolated, and model output values, facilitating the identification of safe zones in health risk assessments. This method also provides a strategy for collecting soil samples at shorter distances after a real fire, thereby reducing labor costs. The specific fitting method is as follows: determine the functional relationship between PAHs concentration and distance in soil samples at the fire scene, extend the curve backward, and obtain PAHs concentrations in soil at greater distances within a range of less than 150 m; determine the functional relationship between PAHs concentration and distance in the CALPUFF model output data, and extend the curve forward to determine PAHs concentrations in soil at closer distances, greater than 500 m; and obtain PAHs concentration values ​​in the soil within the intermediate range through the above methods. This range can be adjusted according to the actual scale of the fire. OriginPro (2016) was used to perform a nonlinear fitting of the "distance-PAHs concentration in soil" relationship (setting the limiting condition: y0 ≥ 0, and the curve passing through the near-distance maximum and far-distance maximum fixed points respectively), and the final functional relationship was obtained (which conforms to the second-order exponential decay function y = A1e (-x / t1) +A2e (-x / t2) +y0).

[0100] Since it is impossible to conduct an on-site fire test at the Dongyuan 110KV substation according to the set scenario of complete combustion of 13.75 tons of 50% transformer oil, this embodiment conducts a full-scale transformer fire test with 1 / 3 of the combustion volume of the fire scenario. Assuming that the two have the same underlying surface and soil conditions, the PAHs concentration in the on-site soil obtained from the full-scale fire test is magnified by 3 times and used as the PAHs concentration in the soil at close range of the set fire scenario (satisfying y = -0.92ln(x) -1.75). After extending backward, the PAHs concentration values ​​at other distances within a range of 150m are obtained. The PAHs concentration obtained by CALPUFF output under the meteorological conditions of Scenario 3 in 4.2.3 is used as the PAHs concentration in the soil at long distances (satisfying y = 1.233e -x / 0.719 +1.203e -x / 0.713 +3.795×10-6 ), extending forward to obtain PAHs concentration values ​​at other distances beyond 500m. Selecting representative distance point values ​​as interpolation values, combining the close-range measured values ​​and the model output values, the function of the variation of PAHs concentration in the soil with distance after the fire at Dongyuan 110KV substation under scenario 3 was obtained, as shown in the figure below: Figure 2 As shown, y=3.143e -x / 0.042 +0.871e -x / 0.109 Using this function, we calculated that at approximately 263 m, the soil PAHs concentration was equal to the average background PAHs concentration in the soil near the Dongyuan substation (84.00 ng / g). At the fire source (x = 0), the soil ΣPAHs concentration was 4014 ng / g, and the ΣBaPeq was 483.59 ng / g, both significantly greater than the background values ​​in the substation soil.

[0101] 3. Analyze the concentration of PAHs in other exposure media:

[0102] Under the proposed fire scenario, PAHs generated after entering the soil would partially remain there, while some would enter groundwater with rainfall and other factors. Furthermore, the substation is located southwest of a vegetable field, primarily cultivated with carrots. If the fire-contaminated soil is not treated and vegetable cultivation continues, some PAHs in the soil could be transferred to the vegetables and ingested by humans. Furthermore, PAHs carried by firefighting wastewater, water-soluble transformer oil fume, and residual debris generated during the firefighting process, if not promptly discharged into sewer pipes, could also enter nearby surface waters with surface runoff and rainfall. Because it was impossible to simulate the proposed fire scenario and collect on-site samples, it was impossible to measure the specific PAHs entering the vegetables, surface water, and groundwater environment after the fire. Therefore, we assumed the proportions of PAHs entering different exposure media from contaminated soil and on-site wastewater to determine PAH concentrations in these media.

[0103] According to soil leaching experiments, under the influence of meteorological conditions such as rainfall, the proportion of PAHs in the soil entering groundwater is 0.001%, which is used as the proportion of soil PAHs distributed into groundwater. In addition, studies have shown that the content of PAHs in plants is significantly positively correlated with the content and composition of PAHs in soil and atmospheric deposition. [119-120] The enrichment level in the root system is much greater than that in other parts.

[121] At the same time, root vegetables have a much greater ability to accumulate PAHs than other vegetables.

[122] . Carrots are typical root vegetables and have a stronger ability to enrich PAHs in the soil. The enrichment capacity is often calculated by the ratio of the PAHs concentration in vegetables to the PAHs concentration in the soil (enrichment coefficient CF). Therefore, the distribution ratio of PAHs in carrots and soil can be determined based on the known CF value of carrots to PAHs in soil. Affected by plant physiology and soil characteristics, the CF values ​​of different plants are different. Since the CF of 16 polycyclic aromatic hydrocarbons (ΣPAHs) in carrots grown in wastewater-irrigated soil is 0.64, the proportion of 4-ring PAHs is high, which is similar to the soil composition, among which the enrichment coefficient of fluoranthene is as high as 0.93; the composition of PAHs in carrots is similar to that in soil, mainly 4 to 6 rings; the enrichment of 3 and 4-ring PAHs in carrots accounts for 94% of the total, which is greater than the proportion in soil (72%); the CF of ΣPAHs in carrots is 0.67. Overall, the composition characteristics of PAHs in carrots are significantly affected by the composition of PAHs in the soil itself. The mean ΣPAHs enrichment coefficient for carrots in soil was used as the ratio of PAH concentrations in the residual soil to PAHs enriched by carrots, which was 1:0.65. Based on this, the distribution ratio of PAHs ultimately entering the soil among the different exposure media was determined to be approximately 60.605% (soil residues): 39.394% (vegetables): 0.001% (groundwater).

[0104] In addition, there is surface water within 500m of the substation. The total ΣPAHs concentration in the firefighting wastewater at the full-scale transformer fire scene (including firefighting water and transformer oil smoke and residue dissolved in water) was measured to be 0.0534±0.0095mg / L. Since the volume of firefighting water sprayed in large-scale fires will also increase further, the value is not amplified and is used as the on-site wastewater concentration under the proposed fire scenario. eq The concentration of PAHs in wastewater is 0.03±0.04ng / mL, which just reaches the maximum discharge threshold of BaP (0.03ng / mL) stipulated in the Integrated Wastewater Discharge Standard and can be discharged directly into the drainage system. However, if a large amount of wastewater is not discharged into the sewage pipe in time, some of the PAHs carried in the wastewater will enter the nearby surface water in various ways, causing water pollution. Surface runoff is the main way for PAHs to migrate to the aquatic environment.

[127] In bioretention

[128] Under the influence of factors such as water quality and soil interception, the concentration of PAHs will decay with the runoff process.

[129] Different surface layers will also affect the PAHs concentration in the runoff process. Asphalt pavement may even increase the PAHs concentration in the runoff.

[130] Therefore, considering the possibility that wastewater may flow into surface water bodies, and taking into account the effects of runoff attenuation and surface water dilution, the PAHs concentration that may enter nearby surface water is calculated as 10% of the PAHs concentration in the wastewater at the fire scene (0.0053 mg / L).

[0105] 4. Human health risk assessment:

[0106] 4.1 Parameter determination

[0107] With reference to the Canadian Industrial Chemicals Assessment and Management Methods, the USEPA Exposure Factor Book, the Technical Guidelines for Risk Assessment of Contaminated Sites (HJ 25.3-2019), and the recommended values ​​in relevant literature, the values ​​of different exposure parameters 5 were determined as shown in Table 1.

[0108] Table 1 Human health risk assessment parameters

[0109]

[0110]

[0111] 4.2 Calculation of carcinogenic risk (CR) and non-carcinogenic risk (HI) of PAHs through different exposure pathways:

[0112] According to the set fire scenario, the exposure routes of human body to PAHs in the residues after the fire include inhalation of soil PAHs (inh-soil), oral ingestion of soil PAHs (oral-soil), skin contact with soil PAHs (dermal-soil), oral ingestion of food PAHs (oral-food), oral drinking of surface water PAHs (oral-water1), direct skin contact with surface water PAHs (dermal-water1), oral drinking of groundwater PAHs (oral-water2), and direct skin contact with groundwater PAHs (dermal-water2).

[0113] Table 2 shows the carcinogenic and non-carcinogenic risks of PAHs entering the human body through the eight pathways mentioned above. Analysis of the contribution of different exposure pathways to the carcinogenic and non-carcinogenic risks reveals the following pattern: ingestion of food contributes the most to the health risk for adults and children (>39%), while dermal contact with groundwater contributes the least, i.e., direct ingestion > dermal contact > inhalation. For different exposure media, the overall risk is food (50.32%) > surface water (37.72%) > soil (11.33%) > groundwater (0.63%). However, the health risk posed by inhalation exposure to soil for children (16.70%) is much greater than that for adults (5.96%). Overall, ingestion of food and drinking surface water are significant sources of health risk from PAHs in the substation fire residue.

[0114] Table 2 Carcinogenic and non-carcinogenic risks of different exposure pathways

[0115]

[0116] 4.3 Carcinogenic risk assessment:

[0117] Since the carcinogenic effect is additive, the carcinogenic risk of all PAHs exposure pathways is accumulated to obtain the total carcinogenic risk, and the relationship between "distance from the fire source-total carcinogenic risk" is obtained as follows: Figure 3 According to the criteria for determining the carcinogenic risk of PAHs to human health, the fire-affected area is divided into three areas: the risk acceptable area, the potential carcinogenic risk area, and the carcinogenic risk area. The figure shows the carcinogenic risk contour line. When the risk value is greater than 10 -4 At 10 -4 to 10 -6 Between 10 and 20, it is a potential carcinogenic risk area; less than 10 -6 When , it is the risk acceptable zone.

[0118] Under the proposed fire scenario, the relationship between adult cancer risk and distance satisfies y = 1.14 × 10 -4 ×e -x / 0.02 +1.15×10 -4 ×e -x / 0.03 , CR ranges from 0 to 2.3×10 -4 Between the range; children meet y = 6.94 × 10 -5 ×e -x / 0.03 +6.88×10 -5 ×e -x / 0.03 , the risk range is from 0 to 1.4×10 -4 The range of the potential cancer risk area is larger than the cancer risk area. For adults, the risk within 23m from the substation fire source is greater than 10 -4, which is a cancer risk area; after 160m, the risk is 10 -6 , which is in the acceptable risk zone. At 1000m, the carcinogenic risk value is reduced to 10 -18 For children, the cancer risk range is smaller than that of adults. The cancer risk zone is within 10m; at 81m, the risk value is 10 -5 ; After 143m, it enters the risk acceptable zone; at 1000m, the risk value drops to 10 -17 Overall, the cancer risk in adults is greater than that in children. The difference in cancer risk may be affected by differences in exposure duration during the setting of parameters. Overall, there was no significant difference in the total cancer risk between adults and children (P>0.05). Although the cancer risk in children is lower than that in adults, their higher sensitivity to toxic substances cannot be ignored in the evaluation process.

[0119] Since PAH in food contributes most to the risk of cancer in humans, if residents consciously avoid eating vegetables grown on contaminated soil after the fire, further analysis will ignore other total cancer risks through food exposure, such as Figure 4 As shown in the figure, the carcinogenic risk zone and potential carcinogenic risk zone have both decreased accordingly, but there has been no significant change. For adults, the carcinogenic risk zone has decreased to within 15 meters, and the acceptable risk zone is beyond 101 meters. For children, the carcinogenic risk zone and potential carcinogenic risk zone are within 6 meters and 117 meters, respectively. The potential carcinogenic risk range for children has increased. In summary, although the risk from food ingestion is the greatest, after a substation fire, the risk cannot be reduced simply by avoiding vegetable cultivation in the fire area. It is still necessary to implement appropriate risk management and control measures.

[0120] 4.4 Non-carcinogenic risk assessment

[0121] For non-carcinogenic risk, when the non-carcinogenic risk HI>1, it means that PAHs in the environment have non-carcinogenic risk to human body. If it is the opposite, the risk impact can be ignored. The non-carcinogenic risk assessment of the set fire scenario is carried out, and the assessment results are as follows: Figure 5As shown. The cumulative non-carcinogenic risk of PAHs is far less than 1, posing no non-carcinogenic risk to humans. The non-carcinogenic risk for adults (0.007) is slightly greater than that for children (0.004). The risk value drops below 0 after approximately 450 meters. The non-carcinogenic risk posed to humans by PAHs generated in a substation fire is significantly lower than the carcinogenic risk. Considering the extreme case, where the carcinogenic risk (HI) equals 1, the calculation shows that adults and children present a non-carcinogenic risk at the fire site when amplified by 145 and 251 times, respectively, under the proposed fire scenario. Amplification by the same factor increases the carcinogenic risk accordingly. Based on this, the carcinogenic risk of PAHs to humans should be the primary consideration after a transformer oil fire. However, since non-carcinogenic effects are also cumulative, considering extreme cases, when transformer oil combustion is larger or fires occur more frequently, the non-carcinogenic risk needs to be evaluated.

[0122] 4.5 Total toxicity equivalent evaluation

[0123] In order to better determine the toxicity of PAHs produced by fire in different exposure media, the range of carcinogenic risk area and potential carcinogenic risk area obtained by carcinogenic risk assessment was combined with the total benzo[a]pyrene toxic equivalent concentration (ΣBaP) of PAHs in soil, surface water, groundwater and vegetables at the critical point. eq ), after comparing the results, provide a reference for the final division of the safe area. Table 3 shows the ΣBaP in different exposure media eq . Still shows that food is good for ΣBaP eq The contribution is the largest. Within the designated carcinogenic risk zone (23m), the surface water concentration seriously exceeds the national BaP threshold (0.0028ng / mL). At the same time, referring to the "Limits of Contaminants in Food" (GB 2762-2005), the BaP content in food cannot exceed 5μg / kg. In the carcinogenic risk zone, the concentration of BaP in carrots is 0.0028ng / mL. eq The value is 4-5 times higher than the national standard. Taking 5μg / kg as the reference value, the BaP enrichment in food after 106m is calculated to be lower than the national standard. eq It is lower than the BaP risk screening value of 0.55 mg / kg specified in the Soil Environmental Quality Standard Agricultural Land Soil Pollution Risk Control Standard (GB15618-2018). Outside the potential risk range, ΣBaP in different exposure media eq Both are lower than the national standard.

[0124] Table 3 ΣBaP in different exposure media eq

[0125]

[0126]

[0127] It should be noted that the above-mentioned substation fire residue risk assessment method system is also used to implement the above-mentioned Figure 1 The method steps corresponding to each embodiment of the method for risk assessment of substation fire residues shown are not repeated in this application.

[0128] It should be noted that the functional units / modules in the various embodiments of the present invention may be integrated into a single processing unit / module, each unit / module may exist physically separately, or two or more units / modules may be integrated into a single unit / module. The aforementioned integrated units / modules may be implemented in the form of hardware or software functional units / modules.

[0129] Through the description of the above embodiments, it will be clear to those skilled in the art that the embodiments described herein can be implemented in hardware, software, firmware, middleware, code, or any appropriate combination thereof. For hardware implementation, the processor can be implemented in one or more of the following units: an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, other electronic units designed to implement the functions described herein, or a combination thereof. For software implementation, part or all of the processes of the embodiments can be completed by instructing the relevant hardware through a computer program. During implementation, the above program can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transmission of computer programs from one place to another. The storage medium can be any available medium that can be accessed by a computer. Computer-readable media can include, but are not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should analyze that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for risk assessment of fire residues in a substation, characterized in that: The following steps are involved: Identify several exposure media for fire residues; Identify several exposure pathways for fire debris; calculating a concentration of fire residues in a first exposure medium, where the first exposure medium is the exposure medium that the fire residues first enter among the plurality of exposure pathways; Setting a distribution ratio of the fire residues from the first exposure medium to the other exposure mediums; and calculating the fire residue concentrations in the other exposure mediums based on the distribution ratio and the fire residue concentration in the first exposure medium. Based on the concentration of fire residues in different exposure media, the average daily exposure to fire residues in different exposure pathways was calculated; Calculate the carcinogenic and non-carcinogenic risks of fire residues from different exposure pathways based on the average daily exposure to fire residues; Also includes: Fit the functional relationship between the distance from the first exposure medium to the fire source and the concentration of fire residues in the first exposure medium, and calculate the concentration of fire residues in the first exposure medium at different distances; Calculate the carcinogenic risk of fire residues at different distances and different exposure pathways based on the concentration of fire residues in the first exposure medium at the different distances; The total carcinogenic risk is obtained by adding up the carcinogenic risks of fire residues at the same distance and different exposure pathways; According to the total carcinogenic risk, the fire-affected area is divided into the risk-acceptable area, the potential carcinogenic risk area and the carcinogenic risk area; The functional relationship between the distance between the first exposure medium and the fire source and the concentration of the fire residue in the first exposure medium is specifically: Within the first distance from the fire source, the fire residue concentration in the first exposure medium is obtained through on-site measurement; outside the second distance from the fire source, the fire plume deposition flux is obtained and converted into the fire residue concentration in the first exposure medium; within the second distance outside the first distance from the fire source, the fire residue concentration in the first exposure medium is calculated by extrapolation or interpolation; based on the fire residue concentration in the first exposure medium, a nonlinear fitting is performed on the distance of the first exposure medium from the fire source and the fire residue concentration in the first exposure medium to obtain the functional relationship between the fire residue concentration in the first exposure medium and the distance.

2. A substation fire residue risk assessment method according to claim 1, characterized in that: Also includes: At the critical point between the designated carcinogenic risk zone and the potential carcinogenic risk zone, the total benzo[a]pyrene toxic equivalent concentration of fire residues in each exposure medium was calculated.

3. A substation fire residue risk assessment method according to claim 1, characterized in that: The calculation of the carcinogenic risk of fire residues under different exposure pathways is expressed as follows: Where, Indicates the carcinogenic risk of fire residues to humans under the nth exposure route; It represents the average daily exposure of fire residues under the nth exposure pathway; Carcinogenicity slope factors for fire residues under the nth exposure route.

4. A substation fire residue risk assessment method according to claim 1, characterized in that: The calculation of the non-carcinogenic risk of fire residues under different exposure pathways is expressed as follows: Where, Indicates the non-carcinogenic risk of fire residues to humans under the nth exposure route; It represents the average daily exposure of fire residues under the nth exposure pathway; It represents the long-term ingestion reference dose of fire residues under the nth exposure mode.

5. A substation fire residue risk assessment system, characterized in that: include: a parameter confirmation unit, the parameter confirmation unit being configured to determine a plurality of exposure media for the fire residue, determine a plurality of exposure pathways for the fire residue, and set a distribution ratio of the fire residue from a first exposure medium to other exposure media, the first exposure medium being the first exposure medium that the fire residue enters among the plurality of exposure pathways; a data processing unit configured to calculate a concentration of fire residues in a first exposure medium, calculate the concentrations of fire residues in other exposure media based on the distribution ratio and the concentration of fire residues in the first exposure medium, calculate an average daily exposure to fire residues in each exposure pathway based on the concentrations of fire residues in each exposure medium, and calculate a carcinogenic risk and a non-carcinogenic risk of fire residues in each exposure pathway based on the average daily exposure to fire residues; The data processing unit is also used to: Fit the functional relationship between the distance from the first exposure medium to the fire source and the concentration of fire residues in the first exposure medium, and calculate the concentration of fire residues in the first exposure medium at different distances; Calculate the carcinogenic risk of fire residues at different distances and different exposure pathways based on the concentration of fire residues in the first exposure medium at the different distances; The total carcinogenic risk is obtained by adding up the carcinogenic risks of fire residues at the same distance and different exposure pathways; According to the total carcinogenic risk, the fire-affected area is divided into the risk-acceptable area, the potential carcinogenic risk area and the carcinogenic risk area; The functional relationship between the distance between the first exposure medium and the fire source and the concentration of the fire residue in the first exposure medium is specifically: Within the first distance from the fire source, the fire residue concentration in the first exposure medium is obtained through on-site measurement; outside the second distance from the fire source, the fire plume deposition flux is obtained and converted into the fire residue concentration in the first exposure medium; within the second distance outside the first distance from the fire source, the fire residue concentration in the first exposure medium is calculated by extrapolation or interpolation; based on the fire residue concentration in the first exposure medium, a nonlinear fitting is performed on the distance of the first exposure medium from the fire source and the fire residue concentration in the first exposure medium to obtain the functional relationship between the fire residue concentration in the first exposure medium and the distance.

6. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 4.

7. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is configured to read the executable instructions from the memory and execute the instructions to implement the method according to any one of claims 1 to 4.

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