The study is devoted to the decision-making theory, its philosophical foundations and certain algorithms of practical activities. The paper is focused on activities in the field of nuclear industry. The functioning of a technologically complex and large enterprise, for example, a nuclear power plant, is impossible without a complex management system, and the decision-making process is one of its elements. This paper is the primary description of the topic and its goal is to formulate approaches to several questions: why do we need a decision-making theory in general, how do we evaluate the correctness of an already made decision. The significance of mathematical calculations in decision-making theory is described. The paper defines the basic terms that are used or will be used in the future, such as: methodology, technology, process, risk, human factor. The theoretical (philosophical) foundations that formed the basis of the decision-making doctrine are described, an attempt is made to answer the question why it is needed and by whom this theory is used and for what purpose. The connection between decision-making with the human factor is formulated. The distinction between the concepts of “decision” (as already existing) and “making decision” (as a complex process, a system of management actions, forecasting options and choosing between them) is described. Certain procedures are presented in the implementation of the decisionmaking process in order to show possible approaches, stages and decisionmaking techniques, as well as the readiness to implement a specific solution. The dependence (efficiency) of the management organization on the decisions made and their implementation is indicated. Besides, the paper sets forth the logic of making the “right” decisions based on “information”. The authors conclude about the importance of applying the decisionmaking theory during the safety analysis and predicting the likely extreme situations at nuclear power facilities and the need to continuously improve the management structures.