Insertion time

In nuclear weaponry, '''insertion time''' is the interval required to rearrange a subcritical mass of fissile material into critical mass.<ref>{{Cite web |title=4.1 Elements of Fission Weapon Design |url=https://nuclearweaponarchive.org/Nwfaq/Nfaq4-1.html |access-date=2024-11-28 |website=nuclearweaponarchive.org}}</ref>

Appropriate insertion time is one of the three main requirements to create a working fission atomic bomb. The need for a short insertion time with plutonium-239 is the reason the implosion method was chosen for the first plutonium bomb, while with uranium-235 it is possible to use a gun design.

The basic requirements{{Of what|date=November 2024}} are: * Start with a subcritical system * Create a super prompt critical system * Switch between these two states in a length of time (insertion time) shorter than the time between the random appearance of a neutron in the fissile material through spontaneous fission or by other random processes. * At the right moment, neutrons must be injected into the fissile material to start the fission process. This can be done by several methods. ** Alpha emitters such as polonium or plutonium-238 can be rapidly combined with beryllium to create a neutron source. ** Neutrons can be generated using an electrostatic discharge tube, this tube uses the D-T reaction.

==References== {{reflist}}

{{DEFAULTSORT:Insertion Time}} Category:Nuclear weapons Category:Nuclear physics Category:Nuclear technology