US lab uses lasers, heat to map neptunium for deep-space nuclear fuel

Researchers at Oak Ridge National Laboratory (ORNL) are advancing the study of neptunium, a rare radioactive element crucial for producing plutonium-238 (Pu-238), which powers Radioisotope Thermoelectric Generators (RTGs) used in deep-space missions like NASA’s Perseverance Rover. Since conventional solar panels and batteries are inadequate for the harsh conditions of deep space, Pu-238-based RTGs remain the only reliable power source for long-range spacecraft instruments. To meet increasing demand for these nuclear fuels, the ORNL team is focusing on understanding the chemical and structural properties of neptunium through thermal decomposition, heating the element between 150°C and 600°C to identify its intermediate transformation phases. The researchers combined Raman spectroscopy—a laser-based technique that maps molecular vibrations—with computational modeling to create the first-ever “structural fingerprint” of a key neptunium oxide. This approach allowed them to observe how the material’s bonding environment changes under heat in real time,