This paper presents a probabilistic concept of fragmentation risk assessment based on simulation modeling. An original probabilistic mass method for the assessment of fragmentation scenarios of a tank has been proposed. It has been concluded that the generation of individual fragments is accompanied by aleatoric uncertainty, regardless of their mass. The highest frequency of fragmentation occurs with generation of two fragments (17%) and three fragments (average 11%) if their masses range from 10% to 20% of the total mass of the tank. The epistemic uncertainty of the velocity, acceleration and attack angle of a fragment is eliminated by the introduction of initial acceleration and uniform fluctuation of variable parameters (coefficients of aerodynamic and lift acceleration). The range of fragments having a mass between 200 kg and 3500 kg can be adequately described by Weibull's distribution, while 70% of the fragments have a range of 298 m-902 m (average 638 m). The proposed methodological concept has been realized in terms of eliminating epistemic uncertainty in the fragmentation of a tank and is applicable to the analysis of explosions of a variety of process equipment in the process industry.