Уран-238 (Uranium-238) is a naturally occurring isotope of uranium, making up about 99.3% of all uranium found in nature. It has a long half-life of approximately 4.5 billion years, which means it decays very slowly. This isotope is not fissile, meaning it cannot sustain a nuclear chain reaction on its own, but it can be converted into плутоній-239 (Plutonium-239) in a nuclear reactor. Уран-238 is primarily used in the nuclear industry, particularly in the production of nuclear fuel and in the development of nuclear weapons. It also plays a role in geological dating and is a source of радіоактивність (radioactivity) in the environment. Its presence in soil and rocks contributes to natural background radiation levels.