Operation Plumbbob

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title: "Operation Plumbbob" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["explosions-in-1957", "nevada-test-site-nuclear-explosive-tests", "radiation-health-effects-research", "1957-in-military-history", "1957-in-nevada", "1957-in-the-environment"] description: "Series of 1950s American nuclear tests" topic_path: "history" source: "https://en.wikipedia.org/wiki/Operation_Plumbbob" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Series of 1950s American nuclear tests ::

::data[format=table title="Infobox nuclear weapons test"]

Field	Value
name	Operation Plumbbob
picture	[[File:Plumbbob Priscilla2.gif
picture_description	Plumbbob-Priscilla, 37 kilotons
country	United States
test_site	{{plainlist
period	1957
number_of_tests	29
test_type	balloon, dry surface, high alt rocket (30–80 km), tower, underground shaft, tunnel
max_yield	74 ktTNT
previous_series	Project 57
next_series	Project 58/58A
::

|name = Operation Plumbbob |picture = [[File:Plumbbob Priscilla2.gif|300px]] |picture_description = Plumbbob-Priscilla, 37 kilotons |country = United States |test_site = {{plainlist|

• NTS Area 12, Rainier Mesa
• NTS Areas 5, 11, Frenchman Flat
• NTS, Areas 1–4, 6–10, Yucca Flat}} |period = 1957 |number_of_tests = 29 |test_type = balloon, dry surface, high alt rocket (30–80 km), tower, underground shaft, tunnel |max_yield = 74 ktTNT |previous_series = Project 57 |next_series = Project 58/58A 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.

Background

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. 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.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/7/7b/Plumbbob.webm" caption="''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.

John 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 18,500 and 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.

::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/07/Operation_Plumbob_Weapons_Development_Report_1957.webm" caption="''Operation Plumbob: Weapons Development Report'' (1957) Official AEC information film reel."] ::

Rainier 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.

Priscilla 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

Pascal-B 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 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. During the Pascal-B nuclear test of August 1957,{{cite web |url = https://www.businessinsider.com/fastest-object-robert-brownlee-2016-2?r=US&IR=T#brownlee-wanted-to-measure-how-fast-the-iron-cap-flew-off-the-column-so-he-designed-a-second-experiment-pascal-b-9 |author = Harrington, Rebecca |date = February 5, 2016 |title = The fastest object ever launched was a manhole cover – here's the story from the guy who shot it into space |work = Tech Insider - www.businessinsider.com Business Insider |accessdate = 11 June 2021 |archive-date = November 1, 2020 |archive-url = https://web.archive.org/web/20201101025542/https://www.businessinsider.com/fastest-object-robert-brownlee-2016-2?r=US&IR=T#brownlee-wanted-to-measure-how-fast-the-iron-cap-flew-off-the-column-so-he-designed-a-second-experiment-pascal-b-9 |url-status = live

List of tests

::data[format=table title="United States' Plumbbob series tests and detonations"] | Name | Date time (UT) (local: PST, −8 hrs)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 | LocationRough 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 + height 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. | Delivery 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. Purpose Include weapons development, weapon effects, safety test, transport safety test, war, science, joint verification and industrial/peaceful, which may be further broken down. | DeviceDesignations 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. | YieldEstimated energy yield in tons or kilotons. A ton of TNT equivalent is defined as 4.184 gigajoules (1 gigacalorie). | FalloutRadioactive 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 | Notes | BoltzmannBoltzmann | FranklinFranklin | LassenLassen | WilsonWilson | PriscillaPriscilla | Coulomb-ACoulomb-A | *Hood*Hood | DiabloDiablo | JohnJohn | KeplerKepler | OwensOwens | Pascal-A | StokesStokes | SaturnSaturn | ShastaShasta | DopplerDoppler | Pascal-BPascal-B | Franklin PrimeFranklin Prime | SmokySmoky | GalileoGalileo | WheelerWheeler | Coulomb-BCoulomb-B | LaplaceLaplace | FizeauFizeau | NewtonNewton | RainierRainier | WhitneyWhitney | CharlestonCharleston | MorganMorgan | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 11:55:00.2 | NTS Area 7c | 1294 m + 150 m | tower, weapons development | XW-40 | | I-131 venting detected, 1.9 MCi | | XW-40 lightweight boosted fission warhead test. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 11:54:59.9 | NTS Area T3 | 1229 m + 90 m | tower, weapons development | XW-30 ? | | I-131 venting detected, 19 kCi | | XW-30 warhead test, fizzled. Retested successfully with Franklin Prime, with more fissile material in the core and different explosives. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 11:45:00.3 | NTS Area B9a ~ | 1595 m + 150 m | balloon, weapons development | | | I-131 venting detected, 100 Ci | | Fizzle, unboosted all-oralloy small weapon design. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 11:45:00.3 | NTS Area B9a ~ | 1589 m + 150 m | balloon, weapons development | XW-45X1 | | I-131 venting detected, 1.5 MCi | | XW-45X1 Swan test, gas-boosted composite pit. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 13:30:00.1 | NTS Area 5 | 940 m + 210 m | balloon, weapons development | Mk-15/39 primary | | I-131 venting detected, 5.8 MCi | | Effects shot with OTS weapon. Similar to that tested in Redwing Lacrosse. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 17:30:?? | NTS Area S3h | 1231 m + 0 | dry surface, safety experiment | XW-31 | | | | Safety experiment, successful. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 11:40:00.1 | NTS Area B9a ~ | 1285 m + 460 m | balloon, weapons development | Swan primary and Whistle secondary. Full-scale test of device was Hardtack I Maple shot. | | I-131 venting detected, 11 MCi | | 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. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 11:30:00.1 | NTS Area T2b | 1367 m + 150 m | tower, weapons development | Swan | | I-131 venting detected, 2.5 MCi | | Very similar to the Shasta test device. 2 stage. Misfired on 28 June. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 14:00:04.6 | Launch from NTS, Areas 1–4, 6–10, Yucca Flat: 10 , elv: 1220 +; Detonation over NTS | 1280 m + 5639 m | Air launched rocket, weapon effect | W-25 | | I-131 venting detected, 6.1MCi? | | 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. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 11:49:59.9 | NTS Area 4 | 1318 m + 150 m | tower, weapons development | XW-35 primary? | | I-131 venting detected, 1.7 MCi | | ICBM warhead, similar to Hardtack I/Koa. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 13:29:59.7 | NTS Area B9b ~ | 1260 m + 150 m | balloon, weapons development | XW-51 ? | | I-131 venting detected, 1.7 MCi | | Very small boosted plutonium device, XW-51 progenitor. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 08:00:00.0 | NTS Area U3j | 1202 m–150 m | underground shaft, safety experiment | | | I-131 venting detected, 10 kCi | | Originally Galileo A. One-point safety experiment, failure. Expected yield was less than 1 kg. A concrete cylinder perhaps 2 m thick 100 m up the tube disappeared. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:25:00.2 | NTS Area B7b ~ | 1250 m + 460 m | balloon, weapons development | XW-30 | | I-131 venting detected, 2.8 MCi | | Tactical Atomic Demolition Munition (TADM) and Talos SAM warhead. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 00:59:55.1 | NTS Area U12c.02 | 1231 m–39.01 m | tunnel, safety experiment | XW-45X1 | | | | One-point safety experiment; first shot in a Rainier tunnel. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:00:00.0 | NTS Area 2a | 1339 m + 150 m | tower, weapons development | Swan | | I-131 venting detected, 2.5 MCi | | 2 stage thermonuclear design. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:30:00.1 | NTS Area B7b ~ | 1282 m + 460 m | balloon, weapons development | XW-34 ? | | I-131 venting detected, 1.7 MCi | | LASL gas boosted implosion device, possible XW-34 test. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 22:35:00.0 | NTS Area U3d | 1229 m–150 m | underground shaft, safety experiment | | | | | Shaft safety experiment, failed. Sent the shaft cap weighing several hundred pounds (1 ton) at velocity very roughly pre-calculated as 66 km/s; popular claims of it reaching space are disputed, see section above. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:39:59.9 | NTS Area B7b ~ | 1282 m + 230 m | balloon, weapons development | | | I-131 venting detected, 690 kCi | | Retest of Franklin with more U-235. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:30:00.0 | NTS Area T2c | 1367 m + 210 m | tower, weapons development | TX-41 primary | | I-131 venting detected, 6.4 MCi | | 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. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:40:00.0 | NTS Area T1 | 1294 m + 150 m | tower, weapons development | | | I-131 venting detected, 1.9 MCi | | LASL diagnostic/exploratory test of boosted fission device. Desert Rock VIII. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:45:00.0 | NTS Area B9a ~ | 1286 m + 150 m | balloon, weapons development | XW-51 ? | | I-131 venting detected, 27 kCi | | Retest of redesigned Lassen device, possible XW-51 air-to-air warhead progenitor. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 20:05:00.6 | NTS Area S3g | 1225 m + 0 | dry surface, safety experiment | XW-31 | | I-131 venting detected, 42 kCi | | One-point safety experiment, high limits test, expected 1 kg TNT equivalent, max .2 kt - failure. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:59:59.8 | NTS Area B7b ~ | 1282 m + 230 m | balloon, weapons development | XW-33 "Fleegle" | | I-131 venting detected, 140 kCi | | Oralloy gun-type device, for a nuclear artillery shell. The third of only four gun-type weapons, with Little Boy, Grable and Aardvark. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 16:44:59.8 | NTS Area T3b | 1220 m + 150 m | tower, weapons development | XW-34 ? | | I-131 venting detected, 1.7 MCi | | LASL boosted fission device. Possibly a test of the XW-34 depth bomb. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:49:59.9 | NTS Area B7a ~ | 1282 m + 460 m | balloon, weapons development | XW-31 | | I-131 venting detected, 2.1 MCi | | LASL test of XW-31 variant, boosted primary in thermonuclear system mockup. Sounds like a fizzle, but no one says so. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 16:59:59.45 | NTS Area U12b | 2295 m–272.8 m | tunnel, weapons development | W-25 | | | | 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. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:29:59.8 | NTS Area T2 | 1370 m + 150 m | tower, weapons development | W27 primary | | I-131 venting detected, 2.9 MCi | | Test of boosted Swan primary in W-27 thermonuclear system mockup. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 12:59:59.9 | NTS Area B9a ~ | 1285 m + 460 m | balloon, weapons development | | | I-131 venting detected, 1.8 MCi | | UCRL test of a small "clean" tactical 2-stage thermonuclear device. Device fizzled when second stage failed to fire. | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 13:00:00.1 | NTS Area B9a ~ | 1285 m + 150 m | balloon, weapons development | XW-45X1 Swan/Flamingo | | I-131 venting detected, 1.2 MCi | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ::

Gallery

File:Plumbob Hood.gif|Plumbbob-Hood, 74-kilotons File:Plumbbob Fizeau.gif|Plumbbob-Fizeau, 11-kilotons File:Plumbbob galileo.gif|Plumbbob-Galileo, 11-kilotons File:Coulomb-B.gif|Plumbbob-Coulomb-B File:PlumbbobRainier.gif|Plumbbob-Rainier, 1.7-kilotons File:Plumbbob Rainier Device.jpg|Plumbbob-Rainier device File:Plumbbob John.gif|Plumbbob-John, 2-kilotons File:Plumbbob John 003.jpg|Plumbbob-John launch, via F-89

Notes

References

References

1. (March 27, 2007). "Dark Circle".
2. Robert Krulwich. (July 17, 2012). "Five Men Agree To Stand Directly Under An Exploding Nuclear Bomb". NPR.
3. Timothy Stenovec. (July 20, 2012). "George Yoshitake, Nuclear Test Photographer, Recalls Filming Nuclear Blast 55 Years Ago". Huffington Post.
4. (January 1, 2015). "Donald Allen Luttrell (obituary)". Dallas Morning News.
5. (October 22, 2013). "Akira "George" Yoshitake (obituary)". Lompoc Record.
6. Sublette, Carey. "Operation Plumbbob".
7. Thomson, Iain. (16 July 2015). "Science: Did speeding American manhole cover beat Sputnik into space? Top boffin speaks to El Reg - How a nuke blast lid may have beaten Soviets by months".
8. Brownlee, Robert R.. (June 2002). "Learning to Contain Underground Nuclear Explosions".
9. Chuck Hansen. (2007). "Swords of Armageddon".
10. (August 2000). "CMR Nuclear Explosion Database (Revision 3)". SMDC Monitoring Research.
11. Hansen, Chuck. (1995). "The Swords of Armageddon, Vol. 8". Chukelea Publications.
12. (1981). "Plumbbob Series, 1957 Final". Defense Nuclear Agency.
13. (1997). "Estimated exposures and thyroid doses received by the American people from Iodine-131 in fallout following Nevada atmospheric nuclear bomb tests". National Cancer Institute.
14. Sublette, Carey. "Nuclear Weapons Archive".
15. (December 1, 2000). "United States Nuclear Tests: July 1945 through September 1992". Department of Energy, Nevada Operations Office.
16. (February 1, 1994). "United States nuclear tests, July 1945 to 31 December 1992 (NWD 94-1)". Natural Resources Defense Council.
17. (July 1, 1994). "Official list of underground nuclear explosions". Sandia National Laboratories.
18. (1981). "Shot Smoky: A Test of the Plumbbob Series, 31 August 1957 (DNA-6004F)". Defense Nuclear Agency, Department of Defense.

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