Complex sentence: It is powered by a nuclear reactor and due to unique spherical construction elements used is believed to be able to operate at a depth of 1000 m. Those elements are hidden inside conventional submarine hull (perhaps for better hydrodynamics and lower noise frame).
Split into simpler sentences: It is powered by a nuclear reactor and is believed to be able to operate at a depth of 1000 m due to the unique spherical construction elements. These elements are hidden inside conventional submarine hull (perhaps for better hydrodynamics and lower noise frame).