Doctoral thesis is dedicated to developing the methodology for economic and environmental losses in high-risk objects. Effective assessment methods increase safety levels and help prepare for a potential accident involving uncontrolled release of a large energy stock, and predict the extent of potential loss in the event of an emergency As part of this paper, modelling of the hazards causing accidents, compiling global emergency statistics has been carried out, and the author has developed a useful, innovative methodology for the calculation of environmental and economic losses, so that all stakeholders, without investing large time resources, can obtain a reliable and reasonable result. The current risk assessment methods has been summarised in the paper and their shortcomings and benefits has been evaluated. The correlation between the depreciation of objects and the increase in the frequency of emergency situations have been analysed in the paper, as well as the proposals for reducing risks during the operational life of the site have been developed and the proposed methodology for assessing losses caused by a potential accident has been offered. The hazard assessment methodology proposed by the author is based on a probit function model that has been used very rarely so far in Latvia. As part of the doctoral thesis, the probit model constants has been tested using different scenarios for possible accidents in the calculation. As part of the doctoral thesis, the methodology algorithm developed by the author is innovative and consists of 6 core blocks: identification of the risk scenario; parameters depending on the surroundings and external meteorological conditions of the high-risk object (hereinafter - HRO); possible risk scenarios and modelling of their probability; identification of negative environmental effects; calculation of probability using the probit model and the assessment of economic and environmental losses. The executing algorithm of the proposed core blocks is closely linked to the efficiency theory, as the sequence of operations and the adoption of effective management decisions, based on the procedure carried out, where different types of data are collected. Using the proposed methodology developed by the author, it may be possible to establish the level of risk at the objects concerned and to foresee potential economic, environmental losses in the event of an accident. The proposed methodology can be used both at the design stage of the installation and in existing high-risk objects. This paper provides a detailed example of the calculation that can be used as a sample. The doctoral thesis is written in Latvian and consists of the introduction, 3 chapters, results and conclusions, the list of bibliography used and 15 annexes. The total volume of the paper is 153 pages of computer text containing 39 images, 52 tables and 15 annexes on 37 pages. The lists of bibliography contains 300 information sources.