American
Nuclear
Weapons
Part of the nuclear arms race
during the Cold War
Tests conducted between 1945 & 1962
Operation Plumbbob
Nevada Test Site

Operation Plumbbob was a series of 29 nuclear tests conducted by the U.S. military between May 28 and October 7, 1957, at the Nevada Test Site. It was one of the longest and most comprehensive test series in the continental United States, and became controversial after much of the operation was declassified. There were several objectives during Operation Plumbbob, including improving tactical weapon design, conducting bio-medical experiments, safety testing, and component and design testing for thermonuclear systems to be detonated in future operations.

Purpose

While most of the shots conducted during Plumbbob were intended to test design principles for nuclear warheads that would be mounted on intercontinental and the intermediate range missiles, warheads with smaller yields were also tested to develop and improve air defense and anti-submarine weapon systems. The military also wanted to understand nuclear blast effects on civil and military structures as well as various aircraft. During one test, a large blimp was subjected to the shock-wave from the nuclear detonation; it collapsed within seconds.

Scientists were also concerned with the effects of radiation on biological life. To study these effects, over 1,200 pigs were subjected to bio-medical experiments and blast-effects studies during Operation Plumbbob. During one test, pigs were placed in cages and provided with suits made of different materials to test which materials provided best protection from the thermal pulse generated by the nuclear blast. While most of the pigs survived, many suffered third-degree burns to 80% of their bodies. In another test, pigs were placed in pens behind large panels of glass at various distances from the epicenter of the nuclear detonation to examine the effects of flying debris on living targets.

Another objective during Operation Plumbbob was to understand how the average foot-solder would perform, physically and psychologically, under the rigors of a tactical nuclear battlefield. Over 16,000 members of the U.S. Air Force, Army, Navy and Marines participated in exercises Desert Rock VII and VIII, a joint field operation which involved the largest troop maneuver associated with U.S. nuclear weapon testing in history.

Military officials were also concerned with radiation contamination and fallout from an accidental detonation of a nuclear weapon. On July 26, a safety experiment, "Pascal-A," was detonated in an uncapped hole at the Nevada Test Site, becoming the first underground shaft nuclear test. The knowledge gained here wouOperation Desert Rockld provide data to prevent nuclear yields in case of accidental detonations (plane crash, etc.). The Rainier shot, conducted September 19, 1957, was the first fully contained underground nuclear test, meaning that no fission products escaped 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.

Operation Doppler was the 13th full-scale nuclear detonation of the Summer 1957 test series, is shown as it rose to an altitude of about 36,000 feet.
Controversy

Operation Plumbbob's controversial legacy stemmed from the enormous amount of radiation released into the atmosphere during the nuclear testing phase. Recently declassified documents reveal that the Plumbbob test series released approximately 58,300 kilocuries of radioiodine (I-131) into the atmosphere over a four month time period. This produced total civilian radiation exposures amounting to 120 million person-rads of thyroid tissue exposure (about 32% of all exposure due to continental nuclear tests). In addition to civilian exposure, troop exercises conducted near the ground near shot "Smoky" exposed over three thousand servicemen to relatively high levels of radiation. A survey of these servicemen in 1980 found significantly elevated rates of leukemia.

Operation Plumbbob
1957
Notable tests from Operation Plumbbob

Information

Test: Stokes
Time: 12:25 7 August 1957 (GMT)
Location: Nevada Test Site (NTS), Area 7b
Test Type: Balloon
Test Height: 1500ft
Yield - Actual (Predicted): 19 kt (10-20 kt)

Comments:

Test of the LASL XW-30 multi-purpose warhead; used in TADM (tactical atomic demolition munition), and Talos SAM (surface-air-missile) warhead. All oralloy (highly enriched uranium) DT gas boosted system. Predicted yield 10-20 kt. Device diameter 22 inches, length 45.8 inches. Nuclear system weight 317 lb., total device weight 448 lb.

Information

Test: Boltzmann
Time: 11:55 28 May 1957 (GMT)
Location: Nevada Test Site (NTS), Area 7c
Test Type: Tower
Test Height: 500ft
Yield - Actual (Predicted): 12 kt (11 kt)

Comments:

XW-40 light weight boosted fission warhead test. The device, developed by Los Alamos Scientific Laboratory (LASL), weighed 295 lb, the nuclear system by itself weighed 144.6 lb. Device width 18 inches, length 31.6 inches. The shot cab held 9 tons of sand, and 15 tons of paraffin as instrument shielding. Predicted yield was 11 kt.

Information

Test: Franklin
Time: 11:55 2 June 1957 (GMT)
Location: Nevada Test Site (NTS), Area 3
Test Type: Tower
Test Height: 300ft
Yield - Actual (Predicted): 140 t (2 kt)

Comments:

This LASL test was a fizzle, yielding only 7% of its predicted 2 kt yield. This was a test of the XW-30 warhead. The device was a boosted all-oralloy fission design. The diameter of the device was 20.8 inches, length 38.4 inches, and the nuclear system weight was 303.8 lb (total weight 448 lb). A modified and enlarged version with more fissile material in the core and a different combination of high explosives was successfully retested in Franklin Prime.

Information

Test: Priscilla
Time: 13:30 24 June 1957 (GMT)
Location: Nevada Test Site (NTS), Area 5
Test Type: Balloon
Test Height: 700ft
Yield - Actual (Predicted): 37 kt (40 kt)

Comments:

Priscilla was a weapons effects test sponsored by the DOD using a stockpiled device of known yield. The device used was a LASL designed Mk-15/39 boosted primary similar to that tested in Redwing Lacrosse. The predicted yield was 40 kt, the same as in the Lacrosse test, but the actual yield was slightly lower. The test device weighed 581.4 lb total (nuclear system weight was 542 lb). It was 27.1 inches in diameter, and was 27.1 inches long.

Information

Test: Hood
Time: 11:40.00.4 5 July 1957 (GMT)
Location: Nevada Test Site (NTS), Area 9a
Test Type: Balloon
Test Height: 1500ft
Yield - Actual (Predicted): 74 kt (60-80 kt)

Comments:

Hood was the largest atmospheric test ever conducted at NTS (and in continental U.S.). This was a test of a two-stage thermonuclear device designed by UCRL (University of California Radiation Laboratory), even though the U.S. government stated at the time that no thermonuclear tests were being conducted in Nevada. The design was intended to fill a gap in 300-400 lb. thermonuclear warhead technology, and was tested at reduced yield. The predicted yield was 60-80 kt. The device used a boosted Swan primary (which gave yields of 12-19 kt in other tests during Plumbbob). About 7 kt of the overall yield was from fusion. The device was a small diameter system (12.1 inches) and was 42.2 inches long. Total device weight was 393 lb. The nuclear test also included troop maneuvers by 2500 Marines, and air operations by 124 aircraft.

Information

Test: Diablo
Time: 11:30.00.1 15 July 1957 (GMT)
Location: Nevada Test Site (NTS), Area 2b
Test Type: Tower
Test Height: 500ft
Yield - Actual (Predicted): 17 kt (11-15 kt)

Comments:

This was a UCRL developmental test of a two stage thermonuclear design. A boosted Swan primary was fired in a mockup of the thermonuclear system. The predicted yield was 11-15 kt, the secondary stage contributed to the total yield. This device was very similar to the Shasta test device. A full yield test of this device was intended for Hardtack I in 1958, and it may be related to the similarly dimensioned Hardtack I Cedar device which produced 220 kt. The diameter of this device was 16.2 inches, length 68.4 inches, and its total weight was 1352 lb.

Information

Test: John
Time: 14:00 19 July 1957 (GMT)
Location: Nevada Test Site (NTS), Area 10
Test Type: Rocket
Test Height: 18,500ft
Yield - Actual (Predicted): 1.7 kt (1.7 kt)

Comments:

This was a combination proof test of the Genie (AIR-2A) nuclear air-to-air rocket, and an effects test of the Genie W-25 warhead. The unguided Genie rocket was fired from a F-89J. The rocket travelled 4240 meters in 4.5 seconds (about Mach 3) after release before detonating. The predicted yield was 1.7 kt. The plutonium core W-25 (probably with a depleted uranium tamper) had a diameter of 17.35 inches, a length of 25.74 inches, and weighed 221 lb.

Information

Test: Kepler
Time: 11:50 24 July 1957 (GMT)
Location: Nevada Test Site (NTS), Area 4
Test Type: Tower
Test Height: 500ft
Yield - Actual (Predicted): 10 kt (11 kt)

Comments:

LASL ICBM warhead development test. Probable test of XW-35 primary in thermonuclear mockup. Similar to Hardtack I Koa device (which was tested at 1.37 Mt in 1958). Kepler had a predicted yield of 11 kt. The device had a diameter of 28.5 inches (72.39cm), and a length of 44 inches (111.76cm). The primary weighed 64.4 lb, the total device weight was 1517 lb.

Information

Test: Doppler
Time: 12:30 23 August 1957 (GMT)
Location: Nevada Test Site (NTS), Area 7
Test Type: Balloon
Test Height: 1500ft
Yield - Actual (Predicted): 11 kt (-)

Comments:

LASL gas boosted implosion device, possible XW-34 test. Satisfactory performance. Device dimensions: diameter 17 inches (43.18cm), length 26 inches (66.04cm). The nuclear system weight 144.6 lb, total device weight 275 lb.

Information

Test: Smoky
Time: 12:30.00.1 31 August 1957 (GMT)
Location: Nevada Test Site (NTS), Area 8
Test Type: Tower
Test Height: 700ft
Yield - Actual (Predicted): 44 kt (45-50 kt)

Comments:

Test of the UCRL TX-41 thermonuclear design. Three stage prototypes of this design were previously fired in Redwing Zuni and Tewa (3.5 Mt and 5 Mt respectively), this test system was reportedly a two stage device, using a boosted primary in a thermonuclear system mockup (perhaps a test of the first two stages of the full three stage design). Some thermonuclear yield was produced by secondary. The predicted yield was 45-50 kt. Device dimensions: diameter 50 inches, length 126.2 inches. Device weight 9408 lb. The Mk-41 eventually became the largest yield nuclear weapon ever developed or deployed by the U.S. (25 megatons). It was had the highest yield to weight ratio of any known weapon (about 6 kt/Kg). Smoky became notorious in the 1970s due to the radiation exposures received by over three thousand servicemen who were brought in as part of the Desert Rock exercises to conduct maneuvers in the vicinity of ground zero shortly after the test. This led to Congressional inquiries and epidemiological evaluation of the affected veterans. A 1980 study of the 3224 participants found a significantly elevated number of leukemia cases. Ten cases of leukemia were found, compared to the expected base number for a similar unexposed population of four.

Information

Test: Fizeau
Time: 16:45 14 September 1957 (GMT)
Location: Nevada Test Site (NTS), Area 3b
Test Type: Tower
Test Height: 500ft
Yield - Actual (Predicted): 11 kt (8-10 kt)

Comments:

LASL boosted fission device. Possibly a test of the XW-34 depth bomb. Device dimensions: diameter 16 inches, length 31.75 inches. Total device weight 131.3 lb. Predicted yield 8-10 kt.

Information

Test: Rainier
Time: 16:59.59.5 19 September 1957 (GMT)
Location: Nevada Test Site (NTS), Area 12
Test Type: Tunnel
Test Height: -899ft
Yield - Actual (Predicted): 1.7 kt (-)

Comments:

UCRL deep underground test shot to evaluate containment and detection of underground nuclear tests. Fired in B-tunnel in side of Ranier Mesa. Modified W-25 warhead used. Device dimensions: diameter 17.4 inches, length 25.7 inches. Device weight 218 lb. Pictures below show the area. The test itself was totally contained.

Operation Plumbbob

Country: United States
Test Site: Nevada Test Site
Test Type: Multiple
Period: 1957
Number of Tests: 29
Total Yield: 74 kilotonnes of TNT (310 TJ)

Comments:

Operation Plumbbob was a series of nuclear tests conducted between May 28 and October 7, 1957, at the Nevada Test Site, following Project 57, and preceding Project 58/58A. It was the biggest, longest, and most controversial test series in the continental United States.



Yield

12 kt
0.5 t
140 t
10 kt
37 kt
74 kt
0 t
1.7 kt
55 t
17 kt
11 kt
10 kt
19 kt
0 t
17 kt
0.3 kt
9.7 kt
4.7 kt
44 kt
11 kt
197 t
0.3 kt
1 kt
11 kt
12 kt
12 Kt
1.7 kt
19 kt
8 kt


74 kt
Code by Luke Hoban