Urchin (detonator)

:"See Urchin disambiguation page for other uses of the word Urchin."

Urchin was the code name for the neutron generating device that triggered the nuclear detonation of the earliest plutonium atomic bombs such as Fat Man, once the critical mass had been "assembled" by the force of conventional explosives. It was also known as the screwball design. [ [http://nuclearweaponarchive.org/Nwfaq/Nfaq8.html Nuclear Weapons FAQ, Section 8.0, Version 2.18: 3 July 2007] ]

A different initiator (code named ABNER) was used for the Little Boy uranium bomb.

Purpose

One of the key elements in the proper operation of a nuclear weapon is initiation of the fission chain reaction at the proper time. To obtain a significant nuclear yield, sufficient neutrons must be present within the supercritical core at just the right time. If the chain reaction starts too soon, the result will be only a 'fizzle yield', well below the design specification; if it occurs too late, there may be no yield whatsoever.

Development

The urchin initiator was developed as part of the Dayton Project under the leadership of Charles Allen Thomas. The Dayton Project was one of the various sites comprising the Manhattan Project

Urchin style initiators were later superseded by other means of generating neutrons such as pulsed neutron emitters that don't use polonium.

In 1949 Mound Laboratories in nearby Miamisburg, Ohio opened as a replacement for the Dayton Project and the new home of nuclear initator research & development.

ee also

* Nuclear weapon design
* Dayton Project

References