Np237

Neptunium-237 (Np-237) is the most long-lived isotope of the element neptunium, with mass number 237 and atomic number 93. It is a radiogenic alpha emitter with a half-life of about 2.14 million years. Its decay is dominated by alpha emission to protactinium-233 (Pa-233), which subsequently beta-decays with a half-life of about 27 days to uranium-233 (U-233). This decay sequence links Np-237 to the thorium fuel cycle via Pa-233 and U-233.

Production and occurrence: Np-237 is produced primarily in nuclear reactors as a byproduct of the uranium fuel cycle and accumulates in spent nuclear fuel and other nuclear waste streams. It is not found in meaningful quantities in nature and is mainly encountered in human-made radioactive systems and disposal contexts.

Applications and production pathways: One notable use of Np-237 is as a target material for the production of Pu-238, a valuable heat source for radioisotope power systems. In reactor irradiation, Np-237 captures a neutron to form Np-238, which beta-decays to Pu-238 with a half-life of about 2 days. Pu-238 has been used in space missions and defense applications as a compact, long-lived heat source.

Safety and handling: Np-237 is a long-lived radiological hazard, primarily hazardous if ingested or inhaled. As a late actinide, it is strongly regulated, requiring remote-handling facilities, specialized chemical separation techniques, and appropriate waste management strategies to minimize environmental and health risks.