Spatial planners need risk assessment input while establishing land-use plans. The purpose is to avoid proximity of industrial hazardous installations and vulnerable neighbourhood. Collaboration between spatial planners and risk assessors in this context still needs to be developed since common forms of risk assessment results do not match the form of input needed for land-use plans. While spatial planning aims at producing precise and justified identification of pieces of territory dedicated to a certain purpose risk assessment provides results in the form of probability of impact area based on analysed accident scenarios. Uncertainty of such scenarios and associated results may be within one or even two orders of magnitude, which makes them non applicable in the context of spatial planning. Therefore, collaboration between spatial planners and risk assessors is inevitable as to overcome these issues. The paper demonstrates weaknesses in accidental scenario development for risk assessment in selected industrial establishments in Slovenia and their implication to modelling results in the context of spatial planning. Due to significant differences, i.e., variations in terms of potential costs, damage to infrastructure, and casualties caused by uncertainty of accident scenarios, the paper shows that only trustworthy risk assessment makes point in decision-making associated with land development.