Pit (nuclear weapon)

In nuclear weapon design, the pit is the core of an implosion nuclear weapon, consisting of fissile material and any neutron reflector or tamper bonded to it. Some weapons tested during the 1950s used pits made with uranium-235 alone, or as a composite with plutonium.^[1] All-plutonium pits are the smallest in diameter and have been the standard since the early 1960s. The pit is named after the hard core found in stonefruit such as peaches and apricots.^[2]

^ "Restricted Data Declassification Decisions from 1945 until Present"Archived 2020-04-04 at the Wayback Machine – "Fact that plutonium and uranium may be bonded to each other in unspecified pits or weapons."
^ National Research Council, ed. (1996). "2 Background". An Evaluation of the Electrometallurgical Approach for Treatment of Excess Weapons Plutonium. Washington DC, USA: The National Academies Press. p. 15. doi:10.17226/9187. ISBN 978-0-309-57330-6. Archived from the original on 30 July 2021. Retrieved 30 July 2021.