Operation Upshot–Knothole

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Operation Upshot–Knothole
Nuclear artillery test Grable Event - Part of Operation Upshot-Knothole.jpg
The Grable test, with the Atomic Annie artillery piece used to fire the warhead.
Country United States
Test site
  • NTS Areas 5, 11, Frenchman Flat
  • NTS, Areas 1-4, 6-10, Yucca Flat
Period 1953
Number of tests 11
Test type free air drop, gun deployed, tower
Max. yield 61 kilotonnes of TNT (260 TJ)
Test series chronology

Operation Upshot–Knothole was a series of eleven nuclear test shots conducted in 1953 at the Nevada Test Site. It followed Operation Ivy and preceded Operation Castle.

Over 21,000 soldiers took part in the ground exercise Desert Rock V in conjunction with the Grable shot.[1] Grable was a 280mm shell fired from the “Atomic Cannon” and was viewed by a number of high-ranking military officials.

The test series was notable as containing the first time an atomic artillery shell was fired (shot Grable), the first two shots (both fizzles) by University of California Radiation Laboratory—Livermore (now Lawrence Livermore National Laboratory), and for testing out some of the thermonuclear components that would be used for the massive thermonuclear series of Operation Castle.

List of tests[edit]

United States' Upshot-Knothole series tests and detonations
Name [note 1] Date time (UT) Local time zone [note 2][2] Location [note 3] Elevation
+ height [note 4]
Delivery [note 5]
Purpose [note 6]
Device [note 7] Yield [note 8] Fallout [note 9] References Notes
Annie 17 March 1953 13:20:00.3 PST (-8 hrs)
NTS Area 3

37°02′52″N 116°01′19″W / 37.0477°N 116.022°W / 37.0477; -116.022 (Annie)

1,230 m (4,040 ft)
+ 90 m (300 ft)
weapons development
TX-5HE "XR-3" Type D pit 16 kt I-131 detected, 2.4 MCi (89 PBq) [3][4][5][6][7] Investigated yield-vs-initiation time curve. Live news coverage. Desert Rock V. Two 2-story houses, 50 autos, bomb shelters in effects test.
Nancy 24 March 1953 13:10:00.0 PST (-8 hrs)
NTS Area 4

37°05′44″N 116°06′13″W / 37.0955°N 116.1037°W / 37.0955; -116.1037 (Nancy)

1,230 m (4,040 ft)
+ 90 m (300 ft)
weapons development
TX-15 "Nevada Zombie" 24 kt I-131 detected, 3.6 MCi (130 PBq) [3][4][5][6][7] Proof test of TX-15. Desert Rock V. Tested RACER boosted primary.
Ruth 31 March 1953 13:00:00.0 PST (-8 hrs)
NTS Area 7

37°04′58″N 116°01′29″W / 37.0827°N 116.0248°W / 37.0827; -116.0248 (Ruth)

1,270 m (4,170 ft)
+ 90 m (300 ft)
weapons development
"Hydride 1" 200 t I-131 detected, 28 kCi (1,000 TBq) [3][4][6][7] 1st UCRL device, a uranium hydride core, meant to be a thermonuclear primary, predicted yield was 1.5 to 3 kilotons. Device fizzled - hydride to slow neutrons was too slow. Embarrassing for designers, as it left 200 ft (61 m) of tower still standing (see image of tower).
Dixie 6 April 1953 15:29:38.4 PST (-8 hrs)
NTS Area 7

37°05′05″N 116°01′08″W / 37.0847°N 116.0189°W / 37.0847; -116.0189 (Dixie)

1,284 m (4,213 ft)
+ 1,830 m (6,000 ft)
free air drop,
weapons development
Mk-5D "Deuterium" 11 kt I-131 detected, 1.7 MCi (63 PBq) [3][4][5][6][7] TX-5D proof test, lithium hydride boost experiment. Exploded 600 ft (180 m) ENE of intended zero point.
Ray 11 April 1953 12:44:59.8 PST (-8 hrs)
NTS Area 4

37°05′56″N 116°05′36″W / 37.09889°N 116.09332°W / 37.09889; -116.09332 (Ray)

1,296 m (4,252 ft)
+ 30 m (98 ft)
weapons development
"Hydride 2" 200 t I-131 detected, 28 kCi (1,000 TBq) [3][4][6][7] 2nd UCRL device, uranium deuteride; it also fizzled. Legend has it that 100 foot tower was used, to avoid embarrassment in case of fizzle.
Badger 18 April 1953 12:35:00.0 PST (-8 hrs)
NTS Area 2

37°08′18″N 116°07′07″W / 37.1383°N 116.1187°W / 37.1383; -116.1187 (Badger)

1,370 m (4,490 ft)
+ 90 m (300 ft)
weapons development
TX-16 "Buzzard" 23 kt I-131 detected, 3.6 MCi (130 PBq) [3][4][5][6][7] Test of the TX-16 cryogenic design. Also tested RACER primary. Desert Rock V.
Simon 25 April 1953 12:29:59.8 PST (-8 hrs)
NTS Area 1

37°03′11″N 116°06′13″W / 37.053°N 116.1036°W / 37.053; -116.1036 (Simon)

1,294 m (4,245 ft)
+ 90 m (300 ft)
weapons development
TX-17/24 "Simultaneity" 43 kt I-131 detected, 6.3 MCi (230 PBq) [3][4][5][6][7] Tested TX-17/24 series, and the RACER primary.
Encore 8 May 1953 15:29:55.4 PST (-8 hrs)
NTS Area 5

36°48′00″N 115°55′44″W / 36.8°N 115.929°W / 36.8; -115.929 (Encore)

940 m (3,080 ft)
+ 740 m (2,430 ft)
free air drop,
weapon effect
Mk-6D 27 kt I-131 detected, 3.9 MCi (140 PBq) [3][4][5][6][7] "Effects" test. Dropped 950 ft (290 m) SSW of target. Desert Rock V, bad exposures for troops and bad downwinder fallout.
Harry 19 May 1953 12:04:59.5 PST (-8 hrs)
NTS Area 3

37°02′25″N 116°01′34″W / 37.0402°N 116.0261°W / 37.0402; -116.0261 (Harry)

1,224 m (4,016 ft)
+ 90 m (300 ft)
weapons development
TX-13D "Hamlet" 32 kt I-131 detected, 4.6 MCi (170 PBq) [3][4][5][6][7] New hollow core design, most efficient pure-plutonium device under 100 kt indicates very good compression. Major effects testing of a high elevation explosion. Heaviest downwind contamination measured.
Grable 25 May 1953 15:30:00.3 PST (-8 hrs)
Launch from NTS Areas 5, 11, Frenchman Flat: 5

36°42′15″N 115°58′26″W / 36.70428°N 115.97387°W / 36.70428; -115.97387 (Launch_Grable), elv: 950 + 5 m (3,117 + 16 ft);
Detonation over NTS 36°47′35″N 115°54′56″W / 36.793°N 115.9156°W / 36.793; -115.9156 (Grable)

960 m (3,150 ft)
+ 160 m (520 ft)
gun deployed,
weapon effect
W9 (nuclear warhead) AFAP "Gun" 15 kt I-131 detected, 2.1 MCi (78 PBq) [3][4][5][6][7] The 2nd of four gun-type device tests. Fired from Annie M65 Atomic Cannon 11 km (6.8 mi) downrange. 280mm shell, 365 kg (805 lb). Detonation at 200 feet (61 m) SW of target. Desert Rock V. Major effects test.
Climax 4 June 1953 11:14:56.7 PST (-8 hrs)
NTS Area 7

37°05′15″N 116°01′09″W / 37.0875°N 116.0192°W / 37.0875; -116.0192 (Climax)

1,288 m (4,226 ft)
+ 410 m (1,350 ft)
free air drop,
weapons development
Mk-7, "Cobra", Type D pit 61 kt I-131 detected, 8.6 MCi (320 PBq) [3][4][5][6][7] Proof test of Mk-7 to be used as a primary in Castle, detonated 320 ft (98 m) NW of target. Composite implosion system in a Type D pit. Used Cyclotol 75/25 explosive mixture.
  1. ^ The US, France and Great Britain have code-named their test events, while the USSR and China did not, and therefore have only test numbers (with some exceptions – Soviet peaceful explosions were named). Word translations into English in parentheses unless the name is a proper noun. A dash followed by a number indicates a member of a salvo event. The US also sometimes named the individual explosions in such a salvo test, which results in "name1 – 1(with name2)". If test is canceled or aborted, then the row data like date and location discloses the intended plans, where known.
  2. ^ To convert the UT time into standard local, add the number of hours in parentheses to the UT time; for local daylight saving time, add one additional hour. If the result is earlier than 00:00, add 24 hours and subtract 1 from the day; if it is 24:00 or later, subtract 24 hours and add 1 to the day. All historical timezone data (excepting Johnston Atoll) are derived from here:
  3. ^ 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.
  4. ^ Elevation is the ground level at the point directly below the explosion relative to sea level; height is the additional distance added or subtracted 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.
  5. ^ Atmospheric, airdrop, balloon, gun, cruise missile, rocket, surface, tower, and barge are all disallowed by the Partial Nuclear Test Ban Treaty. 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.
  6. ^ Include weapons development, weapon effects, safety test, transport safety test, war, science, joint verification and industrial/peaceful, which may be further broken down.
  7. ^ 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.
  8. ^ Estimated energy yield in tons, kilotons, and megatons. A ton of TNT equivalent is defined as 4.184 gigajoules (1 gigacalorie).
  9. ^ 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.


  1. ^ Operation UPSHOT-KNOTHOLE Fact Sheet, Defense Threat Reduction Agency
  2. ^ "Timezone Historical Database". iana.com. Retrieved March 8, 2014. 
  3. ^ a b c d e f g h i j k Estimated exposures and thyroid doses received by the American people from Iodine-131 in fallout following Nevada atmospheric nuclear bomb tests, Chapter 2 (PDF), National Cancer Institute, 1997, retrieved 2014-01-05 
  4. ^ a b c d e f g h i j k Sublette, Carey, Nuclear Weapons Archive, retrieved 2014-01-06 
  5. ^ a b c d e f g h i Hansen, Chuck (1995), The Swords of Armageddon, Vol. 8, Sunnyvale, CA: Chukelea Publications, ISBN 978-0-9791915-1-0 
  6. ^ a b c d e f g h i j k United States Nuclear Tests: July 1945 through September 1992 (PDF) (DOE/NV-209 REV15), Las Vegas, NV: Department of Energy, Nevada Operations Office, 2000-12-01, retrieved 2013-12-18 
  7. ^ a b c d e f g h i j k Yang, Xiaoping; North, Robert; Romney, Carl (August 2000), CMR Nuclear Explosion Database (Revision 3), SMDC Monitoring Research 

External links[edit]