Operation Plumbbob was a series of nuclear tests that were conducted between May 28 and October 7, 1957, at the Nevada Test Site, following Project 57, and preceding Project 58/58A. Other pigs were placed in pens behind large sheets of glass at measured distances from the hypocenter to test the effects of flying debris on living targets.
thumb|Operation Plumbob: Mission Fallout (1957) Official AEC information film reel.
Studies were conducted of radioactive contamination and fallout from a simulated accidental detonation of a weapon, and projects concerning earth motion, blast loading and neutron output were carried out.
Nuclear weapons safety experiments were conducted to study the possibility of a nuclear weapon detonation during an accident. On July 26, 1957, a safety experiment, Pascal-A, was detonated in an unstemmed hole at the Nevada Test Site, becoming the first underground shaft nuclear test. The knowledge gained provided data to predict nuclear yields in case of accidental detonations—for example, in a plane crash.
The John shot on July 19, 1957, was the only test of the Air Force's AIR-2A Genie rocket with a nuclear warhead. It was fired from an F-89J Scorpion fighter over Yucca Flats at the Nevada National Security Site. On the ground, the Air Force carried out a public relations event by having five Air Force officers and a motion picture photographer stand under ground zero of the blast, which took place at between altitude, with the idea of demonstrating the possibility of the use of the weapon over civilian populations without ill effects. The five officers were Colonel Sidney C. Bruce, later professor of Electrical Engineering at Colorado University, died in 2005; Lieutenant Colonel Frank P. Ball, died in 2003; Major John W. Hughes II, died in 1990; Major Norman B. Bodinger, died in 1997; Major Donald A. Luttrell, died in 2014. The videographer, Akira "George" Yoshitake, died in 2013.
thumb|Operation Plumbob: Weapons Development Report (1957) Official AEC information film reel.
The Rainier shot, conducted September 19, 1957, was the first fully contained underground nuclear test, meaning that no fission products were vented into the atmosphere. This test of 1.7 kt could be detected around the world by seismologists using ordinary seismic instruments. The Rainier test became the prototype for larger and more powerful underground tests.
Images from Upshot-Knothole Grable were accidentally relabeled as belonging to the Priscilla shot from Operation Plumbbob in 1957. As a consequence publications including official government documents have the photo mislabeled. The shots can be told apart by the trails of test rockets, which are prominently featured in images and footage of Grable, but appear almost completely absent at the actual Priscilla shot.
Missing steel bore cap
In 1956, Robert Brownlee, from Los Alamos National Laboratory in New Mexico, was asked to examine whether nuclear detonations could be conducted underground. The first subterranean test was the nuclear device known as Pascal A, which was lowered down a borehole. However, the detonated yield turned out to be 50,000 times greater than anticipated, creating a jet of fire that shot hundreds of meters into the sky. a steel lid was welded over the borehole to contain the nuclear blast, despite Brownlee predicting that it would not work. A high-speed camera, which took one frame per millisecond, was focused on the borehole because studying the velocity of the plate was deemed scientifically interesting.
List of tests
{| class="wikitable sortable"
|+ United States' Plumbbob series tests and detonations
|-
! style="background:#fda" | Name
! style="background:#eee" | Date time (UT)<br> (local: PST, −8 hrs)
! style="background:#eee" | Location
! style="background:#fda" | Elevation + height
!style="background:#eee" | Delivery <br />Purpose
!style="background:#eee" | Device
!style="background:#fda" | Yield
!style="background:#eee" class="unsortable" | Fallout
!style="background:#fda" class="unsortable" | References
!style="background:#eee" class="unsortable" | Notes
|-
! Boltzmann
| 11:55:00.2
| NTS Area 7c
| +
| tower,<br />weapons development
| XW-40
| style="text-align:center;" |
| I-131 venting detected,
|
| style="text-align:center;" |
| I-131 venting detected,
|
External links
- Video clips: Historic color footage of shot "Owens", during Operation Plumbbob
- Plumbbob page on the Nuclear Weapons Archive (also refers to manhole cover issue mentioned above).