plutonium235

Plutonium-235, symbol Pu-235, is a radioactive isotope of plutonium with 94 protons and 141 neutrons. It is fissile, meaning it can sustain a nuclear chain reaction with thermal (slow) neutrons. Pu-235 decays by alpha emission to uranium-231, with a half-life of about 703.8 million years, making it long-lived but radiotoxic when ingested or inhaled.

Natural occurrence and production: Pu-235 is not found in meaningful quantities in nature. It is produced artificially in nuclear reactors and appears in trace amounts in reactor-produced plutonium. In typical reactor- or weapon-grade plutonium, Pu-235 is a small fraction relative to other isotopes such as Pu-239 and Pu-241.

Uses and significance: Because of its fissile character, Pu-235 is relevant to discussions of nuclear materials, but Pu-239 and Pu-241 are the principal fissile isotopes used in most reactor fuels and weapons. Pu-235's low abundance and long half-life limit its practical use compared with the major isotopes.

Safety and handling: Pu-235 emits alpha radiation and poses radiological hazards if materials containing it are ingested or inhaled. Handling requires strict containment, monitoring, and regulatory controls to minimize exposure and environmental release.