In the modern world, it is especially important to provide the population and industries with energy, which is necessary to maintain a consistently high quality of life. Often, the process of generating energy is associated with a certain risk to personnel and the public when using various types of fuel, often with fire hazardous properties. For each fire damaging factor, for example, for thermal radiation, toxicity of combustion products, smoke, and elevated temperature, the probability of human injury can be calculated. In this paper, the probability of a person being damaged by thermal radiation in a fire spilling a fuel-air mixture is calculated. A spill fire begins by igniting the vapors of spilled hydrocarbon fuel on an open surface. The calculation was carried out according to three methods, one of which takes into account the movement of a person away from the epicenter of the fire. The dependence of the heat flux density on the distance from the center of the fire is given. Based on calculations of the safe distance from the center of the fire and the values of thermal radiation using the Matlab software environment, the optimal method for determining the probability of human injury in case of a fire spill of an oil product was selected, and it was also concluded that it can be used in case of using high-energy fuel.