Neptunium

Neptunium is a radioactive actinide metal with atomic number 93, produced mainly in nuclear reactors. Its best-known isotope, neptunium-237, is a long-lived product of uranium irradiation.

Neptunium-237: Neptunium’s longest-lived isotope, with a half-life of about 2.14 million years. It accumulates in irradiated uranium and decays through the actinide series.
Nuclear reactor: A system that sustains a controlled nuclear fission chain reaction to produce heat or neutron flux. Reactor neutrons transform uranium into neptunium isotopes.
Edwin McMillan: An American physicist who shared the 1951 Nobel Prize in Chemistry for discoveries in transuranium chemistry. He co-discovered neptunium in 1940 through uranium irradiation.
Uranium: A naturally occurring radioactive actinide metal with atomic number 92. Uranium is neptunium’s immediate periodic-table predecessor and its main reactor precursor.
Neptunium-239: A short-lived neptunium isotope with a half-life of about 2.36 days. It forms when uranium-238 captures a neutron and beta-decays.
Spent nuclear fuel: Used reactor fuel containing residual uranium, plutonium, fission products, and other radioactive nuclides. Neptunium-237 persists in spent fuel and complicates its long-term management.
Philip H. Abelson: An American physicist and science writer who co-discovered neptunium. He identified neptunium-239 after McMillan’s initial experiments.
Plutonium: A radioactive actinide metal with atomic number 94, produced mainly in nuclear reactors. Plutonium follows neptunium in the periodic table and shares its reactor origins.
Uranium-238: The most abundant naturally occurring uranium isotope, which can capture a neutron to form uranium-239. Its neutron-capture chain is a major route to neptunium-239.
Actinide partitioning: The chemical separation of actinide elements from nuclear fuel or radioactive waste. Partitioning can separate neptunium for transmutation or specialized waste treatment.

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Actinide conceptBroader topic: Its discovery helped establish that elements beyond uranium belonged to a coherent series.