The operation consisted of 29 explosions, of which only two did not produce any nuclear yield. Twenty-one laboratories and government agencies were involved. While most Operation Plumbbob tests contributed to the development of warheads for intercontinental and intermediate range missiles, they also tested air defense and anti-submarine warheads with smaller yields. They included 43 military effects tests on civil and military structures, radiation and bio-medical studies, and aircraft structural tests. Operation Plumbbob had the tallest tower tests to date in the U.S. nuclear testing program as well as high-altitude balloon tests. One nuclear test involved the largest troop maneuver ever associated with U.S. nuclear testing.
Approximately 18,000 members of the U.S. Air Force, Army, Navy and Marines participated in exercises Desert Rock VII and VIII during Operation Plumbbob. The military was interested in knowing how the average foot-soldier would stand up, physically and psychologically, to the rigors of the tactical nuclear battlefield.
Almost 1,200 pigs were subjected to bio-medical experiments and blast-effects studies during Operation Plumbbob. On shot Priscilla (37 kt), 719 pigs were used in various experiments on Frenchman Flat. Some pigs were placed in elevated cages and provided with suits made of different materials, to test which materials provided best protection from the thermal radiation. As shown and reported in the PBS documentary Dark Circle, the pigs survived, but with third-degree burns to 80% of their bodies.[2] 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.
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 prevent 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.[3] 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 18,500 and 20,000 feet (5,600 and 6,100 m) altitude, with the idea of demonstrating the possibility of the use of the weapon over civilian populations without ill effects.[4] 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.[5] The videographer, Akira "George" Yoshitake, died in 2013.[6]
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.[7]
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 500 ft (150 m) 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.[8] During the Pascal-B nuclear test of August 1957,[8][9] a 900-kilogram (2,000 lb) iron lid was welded over the borehole to contain the nuclear blast, despite Brownlee predicting that it would not work.[8] When Pascal-B was detonated, the blast went straight up the test shaft, launching the cap into the atmosphere. The plate was never found.[10] Scientists believe compression heating caused the cap to vaporize as it sped through the atmosphere.[8] 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.[8] After the detonation, the plate appeared in only one frame. Regarding its speed Brownlee reckoned that "a lower limit could be calculated by considering the time between frames (and I don't remember what that was)", and joked that the best estimate was it was "going like a bat!".[10] Brownlee estimated that the explosion, combined with the specific design of the shaft, could accelerate the plate to approximately six times Earth's escape velocity.[10]
Largest atmospheric test in CONUS. Was a 2-stage thermonuclear device, even though AEC stated that no thermonuclear devices were being tested at the NTS. Desert Rock VII.
Proof test of AIR-2A Genie air-to-air rocket. Test made famous by five USAF officers and a videographer standing at ground zero below the hypocentre and during the detonation, flash and blast.
Originally Galileo A. One-point safety experiment, failure. Expected yield was less than 1 kg. A concrete cylinder perhaps 2 m (6 ft 7 in) thick 100 m (330 ft) up the tube disappeared.
Shaft safety experiment, failed. Sent the shaft cap weighing several hundred pounds (1 ton) at velocity very roughly pre-calculated as 66 km/s (41 mi/s); popular claims of it reaching space are disputed, see section above.
2 stages of 3 stage thermonuke, similar to Redwing/Zuni and Tewa. Desert Rock VII; 3000 servicemen irradiated; 10 of 4 expected leukemia cases in the 80s. Last pristine air-drop location at the NTS.
First US underground nuclear test. Evaluate containment and detection of underground testing, formed a chimney of broken rock which provided data on possible underground engineering applications of nuclear explosives.
^To convert the UT into standard local PST, subtract 8 hours. If the result is earlier than 00:00, add 24 hours and subtract 1 from the day. Historical time zone data are derived from "Time Zone Historical Database". iana.com. Archived from the original on March 11, 2014. Retrieved March 8, 2014.
^Rough place name and a latitude/longitude reference; for rocket-carried tests, the launch location is specified before the detonation location, if known. Some locations are extremely accurate; others (like airdrops and space blasts) may be quite inaccurate. "~" indicates a likely pro-forma rough location, shared with other tests in that same area.
^Elevation is the ground level at the point directly below the explosion relative to sea level; height is the additional distance added or by tower, balloon, shaft, tunnel, air drop or other contrivance. For rocket bursts the ground level is "N/A". In some cases it is not clear if the height is absolute or relative to ground, for example, Plumbbob/John. No number or units indicates the value is unknown, while "0" means zero. Sorting on this column is by elevation and height added together.
^Atmospheric, airdrop, balloon, gun, cruise missile, rocket, surface, tower, and barge have all been disallowed by the Partial Nuclear Test Ban Treaty since 1963. Sealed shaft and tunnel are underground, and remained useful under the PTBT. Intentional cratering tests are borderline; they occurred under the treaty, were sometimes protested, and generally overlooked if the test was declared to be a peaceful use.
^Include weapons development, weapon effects, safety test, transport safety test, war, science, joint verification and industrial/peaceful, which may be further broken down.
^Designations for test items where known, "?" indicates some uncertainty about the preceding value, nicknames for particular devices in quotes. This category of information is often not officially disclosed.
^Estimated energy yield in tons or kilotons. A ton of TNT equivalent is defined as 4.184 gigajoules (1 gigacalorie).
^Radioactive emission to the atmosphere aside from prompt neutrons, where known. The measured species is only iodine 131 if mentioned, otherwise it is all species. No entry means unknown, probably none if underground and "all" if not; otherwise notation for whether measured on the site only or off the site, where known, and the measured amount of radioactivity released.
References
^ abcdefghijklmnopqrstuvwxyzaaabacadYang, Xiaoping; North, Robert; Romney, Carl (August 2000), CMR Nuclear Explosion Database (Revision 3), SMDC Monitoring Research
^Judy Irving, Chris Beaver, Ruth Landy (directors) (March 27, 2007). Dark Circle (DVD). ISBN0-7670-9304-6. Archived from the original on August 11, 2019. Retrieved September 7, 2017.
^ abcdefghijklmnopqrstuvwxyzaaabac"2", Estimated exposures and thyroid doses received by the American people from Iodine-131 in fallout following Nevada atmospheric nuclear bomb tests, National Cancer Institute, 1997, archived from the original on February 1, 2017, retrieved January 5, 2014
^Shot Smoky: A Test of the Plumbbob Series, 31 August 1957 (DNA-6004F), Washington, DC: Defense Nuclear Agency, Department of Defense, 1981, hdl:2027/uiug.30112075684347
