**5. Risk assessment**

The risk assessment is the final phase of the fragmentation analysis due to the explosion of the LPG tank. Defining fracture probabilities, shape and mass of fragments, as well as kinematic parameters are the basis for defining fragmentation density and sector angles. The fragmentation risk assessment is performed based on the results given in Section 4. Research has shown that the fragmentation effect of a 50,000-liter tank can endanger objects and people at distances greater than 1,000 meters. Therefore, fragmentation stands out as the dominant hazard versus shock wave and thermal effect during tank explosion. Fragmentation risk assessment is carried out by dividing the area around the focus of the accident into quadrants measuring 200 200 meters within which the number of fragments is observed.

A larger number of fragments gives a higher fragmentation risk and vice versa. The fragmentation risk analysis is given for the limit values of the mass factor (0.55 and 0.75), so we obtain the limit values of the fragmentation risk. For example, for quadrant D1 we have that the limit values of fragmentation risk are 5.24% and 4.91%, which gives an average value of 5.08%. Although there is a significant deviation between the limit values of the mass factor (0.55 and 0.75), based on the appropriate risk matrices, we can conclude that the deviation of the limit values of fragmentation risk is only a few percent. This indicates that the presented methodology based on the identification of uncertainties provides convergent and reliable solutions in the assessment of fragmentation risk. Simulations of fragment bursting as well as risk matrices are shown in **Figure 7**.
