Plutonium241

Plutonium-241 (Pu-241) is a radioactive isotope of the element plutonium, defined by a mass number of 241 and an atomic number of 94. It occurs as a component in reactor-produced plutonium and in aged stockpiles where decay products accumulate, contributing to the overall radiological characteristics of plutonium materials.

Production and decay: Pu-241 is formed in reactors by successive neutron captures on Pu-239: Pu-239 captures a neutron to become Pu-240, which captures another neutron to become Pu-241. Pu-241 decays by beta minus emission to americium-241 (Am-241) with a half-life of about 14.3 years. Am-241 is an alpha emitter with a half-life of about 432 years and produces gamma radiation, including a prominent 59.5 keV line, which is detectable in monitoring equipment.

Physical and chemical characteristics: Pu-241 has a relatively high specific activity due to its short half-life. As an isotope of plutonium, it shares chemical properties with other plutonium isotopes and is typically found in oxide form as PuO2 within nuclear materials. In reactor environments it can undergo fission upon neutron absorption, contributing to the neutron economy alongside Pu-239, the primary fissile isotope.

Safety and usage: The decay of Pu-241 to Am-241 increases the long-term gamma activity of plutonium-bearing materials, complicating storage, handling, and safeguards. Am-241’s gamma emissions enable detection and assay of plutonium inventories. Pu-241 is not used on its own as a fuel but is an important component of the isotopic inventory in spent fuel and legacy sources, influencing radiological hazard assessments and fuel-cycle planning.