Uranium is a high‐value energy element, yet also poses an appreciable environmental burden. The demand for a straightforward, low energy, and environmentally friendly method for encapsulating uranium species can be beneficial for long‐term storage of spent uranium fuel and a host of other applications. Leveraging on the low melting point (60 °C) of uranyl nitrate hexahydrate and nanocapillary effect, a uranium compound is entrapped in the hollow core of WS2 nanotubes. Followingly, the product is reduced at elevated temperatures in a hydrogen atmosphere. Nanocrystalline UO2 nanoparticles anchor within the WS2 nanotube lumen are obtained through this procedure. Such methodology can find utilization in the processing of spent nuclear fuel or other highly active radionuclides as well as a fuel for deep space missions. Moreover, the low melting temperatures of different heavy metal‐nitrate hydrates, pave the way for their encapsulation within the hollow core of the WS2 nanotubes, as demonstrated herein.