Np239

Neptunium-239 (Np-239) is a radioactive isotope of the element neptunium (atomic number 93) with a mass number of 239. It is not found naturally on Earth and is produced artificially in nuclear reactors and particle accelerators. In reactor fuel cycles, Np-239 is an intermediate in the production of plutonium-239: uranium-238 captures a neutron to form uranium-239, which beta decays with a half‑life of about 23.5 minutes to neptunium-239; neptunium-239 then beta decays with a half‑life of about 2.356 days to plutonium-239.

Np-239 decays by beta emission to Pu-239. As a member of the actinide series, neptunium exhibits multiple possible oxidation states and forms various compounds; in solution it commonly exists in oxidation states from +3 to +7. In practical handling, it requires specialized, shielded facilities due to its radioactive nature. The decay of Np-239 ultimately yields Pu-239, which is an alpha emitter and fissile material.

Applications and significance: Historically, Np-239 is important as the immediate precursor to Pu-239, the fissile material used in many reactor fuels and nuclear weapons programs. It is produced in small quantities for radiochemical research and as a target or intermediate in experiments related to actinide chemistry and nuclear fuel cycles.

Safety: Np-239 and its compounds are highly radiotoxic if inhaled or ingested. Handling requires containment in shielded hot cells, remote manipulation, and strict regulatory controls.

Discovery: Neptunium was first synthesized in 1940 by Edwin M. McMillan and Philip H. Abelson.