The topic of low-power nuclear power plants has been relevant for more than 50 years. They allow you to conduct electrical energy in remote areas, such as, for example, the Arctic, and to build stations with the possibility of mobile regulation in cases of emergency. Currently, the state corporation Rosatom has launched a broad propaganda about the prospects of these nuclear power plants and has stepped up the construction of the first floating nuclear thermal power plant, which is one of the variants of this type of nuclear power plants. The idea of creating this project has generated a mass of protests from environmental organizations. In this paper, the scenario of a beyond design basis accident at a floating nuclear power plant is considered. Calculation of the damaging factors of this accident. The calculation of prevented damage was made using the existing methodology with some changes made for convenience of calculation, and a formula was introduced for comparing the costs of measures to prevent damage with the magnitude of this damage. The improved methodology can be used in the EMERCOM of Russia system for forecasting emergencies at the facility level. The introduction of this methodology and its practical application for the assessment of prevented damage will make it possible to predict the consequences of the occurrence of emergency situations on energy-saturated objects, objects with a massive presence of people.