Natural uranium is considered the main resource of nuclear power based on thermal neutrons. It is a rather common element, though its concentration in natural substances is usually very low. The cost of production of uranium is an important factor for development of nuclear energy. Depending on the production cost of 1 kg of uranium, uranium ores are classified into four categories of cost. Deposits of uranium ores are distributed unevenly around the globe. Currently, 28 countries mine uranium ore from their bowels, yet only 19 countries produce uranium fuel. In the world there is a significant discrepancy between the countries leading in terms of the world's reserves of uranium and its main consumers. In countries like Australia, Kazakhstan and South Africa, nuclear power is underdeveloped, and uranium consumption is very low or non-existent. These countries have a large uranium resource base and are today global exporters of uranium ores. At the same time, countries like the US, China, Japan, Britain, France, or Germany, by contrast, have a well-developed nuclear industry and a lack of sufficient uranium ore deposits in their territory. They serve, as a rule, as major importers of uranium / uranium ore. The article considers the world's reserves of uranium in different price categories, the global reserves by countries, and unconventional uranium resources; provides an overview of reserves in Russia, the demand for uranium, global production volumes by countries, mining companies, uranium production output in Russia, with general conclusions made on development of the resource base of nuclear power.