Modeling of spatial and temporal assessment of territorial risk in case of accidents during transportation of chemically dangerous goods by rail

Abstract

During the operation of railway transport, various pollutants are emitted into the atmosphere. Sources of pollutants on rail transport are divided into two main classes. The first class is moving sources. The second is stationary sources. From the standpoint of assessing the level of environmental safety and environmental protection, it is necessary to identify two main types of emissions of pollutants. The first type is an organized issue. For example, the emission of fuel combustion products during the operation of a locomotive. The second type is unorganized emission in case of emergencies at the stage of transportation of dangerous goods, their loading or unloading. For example, depressurization of the tank.

This article considers the problem of unorganized emissions of chemically hazardous substances into the atmosphere during the operation of railway rolling stock. The transport of dangerous goods by rail poses a potential threat of large-scale environmental pollution in case of emergencies. The analysis of the situation shows that accidents on the railways of Ukraine occur quite often. The main causes of emergencies during the transportation of chemically dangerous goods by rail are: mechanical damage to capacitive equipment; corrosion, thermal action on capacitive equipment; depressurization of shut-off valves, welded joints; getting into the capacitive equipment of foreign substances; fatigue phenomena in metal, welded elements; equipment defects; errors during the design, manufacture, installation, repair of equipment; lack of optimization of routes for delivery of chemically dangerous goods to the consumer; collision of a train with motor transport at crossings. We should also not forget about the possibility of sabotage at railway facilities. For example, blasting tracks.

During emergencies, large areas of contamination are formed during the transportation of chemically dangerous goods by rail. These pollution zones extend far into the regions adjacent to the railway. There are the following striking factors in emergencies during the transportation of chemically dangerous goods: cloud (train) of toxic substances; the emergence of a fireball; shock wave.

One of the main reasons for exceeding the permissible concentrations of toxic substances and carcinogens in the atmosphere in the surrounding area is the emission of exhaust gases during the operation of main and shunting locomotives and in emergencies during the transportation of chemically dangerous goods.

In the case of emissions of harmful and chemically hazardous substances in transport, the following tasks must be solved: assessment of the scale of pollution; assessment of potential territorial risk; development of measures to protect the environment from pollution.

To solve these problems, it is necessary to develop mathematical models that take into account the specifics of emissions of harmful and dangerous substances at railway facilities.

When transporting chemically hazardous substances by rail, an important safety aspect must be taken into account – the distance between tracks, station areas and residential or industrial buildings. It is related to the requirement to protect, first of all, the population, as well as the territory from possible dangerous factors that arise during emergencies.

Therefore, the purpose of this article is to forecast risk areas for residents of the adjacent accident site with chemically hazardous substances on the railway track, determine the rate of air pollution in the area and provide recommendations for the evacuation of civilians.

In assessing the territorial risk in case of accidents on railway transport, accompanied by the emission of hazardous substances into the atmosphere, the method of spatial-temporal assessment was used. This method takes into account the following factors: the probable value of wind speed and direction; emission intensity; start and end time of the issue; state of the atmosphere; emission source movement.

To forecast the territorial risk, it is necessary to know: the emission power of a hazardous substance; place of possible accident; scenario of meteorological situations; concentration field of a dangerous substance, which is formed for a specific meteorological situation.

Territorial risk assessment in case of emergency leakage of hazardous substances at the railway station is carried out in two stages. Stage I – the calculation of the concentration field of a dangerous substance for a particular meteorological situation is carried out. Stage II – the calculation of the magnitude of territorial risk for each point of the region, taking into account the specified concentration threshold.

Thus, the proposed mathematical model of the method of spatial-temporal assessment of territorial risk in the emission of hazardous substances by rail takes into account various factors. Namely: the influence of different meteorological situations, the power of the emission, the movement of the emission source, the trajectory of the warehouse, and so on. It also shows the speed (time) of propagation of the plume (cloud) of a dangerous substance, which allows the relevant services to carry out the necessary evacuation measures.

The mathematical model of the method of spatial-temporal assessment of territorial risk is recommended to be used in the Head Department of the State Emergency Situations Service of Ukraine (DNSU of Ukraine) in Mykolayiv region to assess the consequences of extreme situations at chemically dangerous facilities in the region and transport.