GB/T 11847-2008 is a national standard for uranium dioxide powder, a key material for the nuclear industry. It specifies the use of BET volumetric method, which is to accurately determine the specific surface area of uranium dioxide powder by measuring the physical adsorption of nitrogen to a certain amount of powder sample at low temperature (usually liquid nitrogen temperature) and applying the classical BET theoretical model to calculate. The standard specifies the method principle, test equipment, sample prepative, experimental operation flow, data processing and reporting requirements, and aims to provide a key, unified and reliable technical basis for the production, research and development and quality control of nuclear fuel components.