Operation PLUMBBOB

Note: For information related to claims, call the Department of Veterans Affairs (VA) at 800-827-1000 or 

the Department of Justice (DOJ) at 800-729-7327. For all other information, call the Nuclear Test 

Personnel Review (NTPR) Program at 800-462-3683.

Operation PLUMBBOB, the sixth series of atmospheric nuclear tests conducted within the continental United 

States, consisted of 24 nuclear detonations and 6 safety tests. The PLUMBBOB series lasted from May 28 to 

October 22, 1957, and involved about 14,000 Department of Defense (DOD) personnel, mostly military service 

personnel, participating in observer programs, tactical maneuvers, and scientific and diagnostic studies. The 

series tested nuclear weapons for possible inclusion in the defense arsenal. The tests were also used to 

improve military tactics, equipment, and training. The safety tests were conducted to ensure that no nuclear 

reaction would occur if the high explosive components of the device were accidentally detonated during 

storage or transport.

Historical Background

During PLUMBBOB, the activity with the largest DOD participation was Exercises Desert Rock VII and VIII, a 

program involving members of all armed services. Exercises Desert Rock VII and VIII included training 

programs, tactical maneuvers, and technical service projects. Training programs generally included lectures 

and briefings on the effects of nuclear weapons, observation of a nuclear detonation, and a subsequent visit to 

a display of military equipment exposed to the detonation. At Shots HOOD, SMOKY, and GALILEO, 

maneuvers were conducted to develop tactics applicable to the nuclear battlefield. At Shot HOOD, the Marine 

Corps conducted a maneuver involving the use of a helicopter airlift and tactical air support. At Shot SMOKY, 

Army troops conducted an airlift assault, and at Shot GALILEO, Army troops were tested to determine their 

psychological reactions to witnessing a nuclear detonation. Technical service projects were designed to test 

equipment and techniques.

In addition to Desert Rock activities, scientific tests to assess the effects of each nuclear detonation were 

conducted by four test groups of the Nevada Test Organization (NTO). The Weapons Effects Test Group was 

sponsored by Field Command, Armed Forces Special Weapons Project (AFSWP). The two Atomic Energy 

Commission (AEC) weapons development laboratories sponsored the Los Alamos Scientific Laboratory 

(LASL) and the University of California Radiation Laboratory (UCRL) Test Groups. Finally, the Federal Civil 

Defense Administration sponsored the Civil Effects Test Group (CETG), which evaluated the effectiveness of 

civil defense measures. Although the Weapons Effects Test Group was the only DOD-sponsored test group, 

DOD personnel took part in the experiments of the other three groups.

Individuals participating in scientific experiments placed data-collection instruments around the point of 

detonation in the days and weeks preceding the scheduled nuclear test. They returned to the test area to 

recover equipment and gather data after the detonation, when the Test Manager had determined that the area 

was safe for limited access.
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Support services for both Exercises Desert Rock VII and VIII and the NTO included radiological safety, 

security, transportation, communications, engineering, and logistics. The Air Force Special Weapons Center 

(AFSWC) at Kirtland Air Force Base, New Mexico, provided aircraft and pilots for pre-shot security sweeps, 

cloud sampling, cloud tracking, and aerial radiological surveys conducted for the NTO. During PLUMBBOB, 

AFSWC also conducted cloud penetration studies for the Weapons Effects Test Group to determine Air Force 

needs in monitoring the accumulation of radioactive contaminants on aircraft.

Radiation Protection Standards

Exercises Desert Rock VII and VIII, the test groups, and AFSWC each developed its own organization and 

procedures for ensuring the radiological safety of its members based on the established criteria of the AEC. 

The radiological safety plans were developed to minimize operational exposures to ionizing radiation.

The safety of Desert Rock VII and VIII participants was the responsibility of the Desert Rock Exercise Director. 

A maximum radiation exposure limit of 5.0 Roentgens (R) in any 6-month period was established for Desert 

Rock troops. Of this exposure, no more than 2.0 R was to be from prompt radiation.

Exposure limits for blast pressure and thermal radiation were also established. Based on exposure limits and 

mode of delivery, minimum distance criteria for positioning Desert Rock troops and observers were 

established. For a tower shot with a predicted maximum yield of about 10 kilotons, troops in the open were 

positioned at least 4,000 yards from ground zero. Troops in trenches at such a shot were positioned no closer 

than 2,600 yards from ground zero. Troops in armored vehicles were positioned no closer than 2,800 yards 

from ground zero.

The Desert Rock Radiological Safety Section implemented procedures for Exercise Desert Rock during

PLUMBBOB. The 50th Chemical Platoon supported the Radiological Safety Section by providing materials, 

equipment, and personnel.

The Test Manager was responsible for the safety of all test group personnel at the Nevada Test Site (NTS) 

during the operation. The radiological safety criteria for test group personnel (in addition to Desert Rock 

personnel) were 3.0 R for any 13-week period and 5.0 R for one calendar year. AFSWC pilots were subject to 

the same exposure limits as the test groups. Onsite radiological safety operations were performed for the Test 

Manager by AEC personnel. The AFSWC implemented its own radiological safety procedures.

Although the missions of Exercise Desert Rock, NTO, and AFSWC required different types of activities and 

separate radiation protection plans and staffs, many of the procedures were similar and were performed by two 

or more of the three radiological safety groups. These procedures included:

• Orientation and training – preparing radiological monitors for their work and familiarizing participants 

with radiological safety procedures

• Personnel dosimetry – issuing, processing, and developing film badges for participants and determining 

gamma radiation exposures recorded on film badges

• Use of protective equipment – providing anti-contamination equipment, including clothing and 

respirators

• Monitoring – performing radiological surveys and controlling access to all contaminated areas

• Briefing – informing observers and project personnel of radiological hazards and the current status of 

contamination in the test area

• Decontamination – detecting and removing contaminated material from personnel and equipment.
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Summaries of Operation PLUMBBOB Nuclear Weapons Tests

The 24 PLUMBBOB test shots and the safety experiments are summarized in the accompanying table, and 

their locations are shown on the accompanying map. Shots PRISCILLA, HOOD, SMOKY, and GALILEO are 

described in the following paragraphs. PRISCILLA is significant due to the large number of participants 

involved and the extensive military effects program. Shots HOOD and SMOKY involved large troop tests. 

Shot GALILEO is significant because some personnel had been at the test site for an extended period of time 

awaiting a decision as to whether they would be able to participate at Shot SMOKY. For a number of reasons,

including delays in the scheduling of SMOKY, the Army troop test was conducted at GALILEO instead of 

SMOKY.

Shot PRISCILLA, a 37-kiloton shot, was detonated from a balloon 700 feet above Frenchman Flat at 6:30 a.m.

on June 24, 1957. While there was no troop maneuver at PRISCILLA, more than 1,700 individuals took part in 

Exercise Desert Rock activities. Most of these individuals were involved in the troop observer indoctrination 

program. The closest troops witnessed the detonation from trenches 3,500 meters southwest of ground zero. 

After the detonation, troops toured the extensive equipment display area, located directly south of ground zero. 

At the time of the first survey, residual radiation greater than 1 R per hour (R/h) was confined to a circular area 

within 550 meters of ground zero. Troops were able to view equipment up to the 5 R/h intensity line located 

500 meters from ground zero.

The primary objective of the PRISCILLA shot was to correlate the yield and characteristics of the device with 

its effects on military equipment, materiel, structures, and ordnance. To fulfill this objective, about 300 AFSWP 

personnel conducted 34 scientific projects, making this shot one of the largest military effects tests ever 

conducted at the NTS. In addition, AFSWC aircrew personnel provided such services to the Test Manager as 

cloud sampling, cloud tracking, and security sweeps. The principal AFSWC unit involved in PRISCILLA, as at 

other shots in the PLUMBBOB series, was the 4950th Test Group (Nuclear), with support from the 4900th Air 

Base Group. During PRISCILLA, AFSWC also conducted the cloud penetration study.

Shot HOOD, a 1,500-foot balloon shot in Yucca Flat, was fired at 4:40 a.m. on July 5, 1957, with a yield of 

74 kilotons. HOOD was the largest atmospheric detonation to occur at the NTS. Residual radiation greater 

than 1 R/h at the time of the first survey was confined to a circular area 1,000 meters from ground zero.

Exercise Desert Rock programs included troop observer and indoctrination projects, a troop test, radiological 

training projects, and technical service projects. Over 3,000 DOD personnel participated in these projects, the 

largest being the Marine Brigade Exercise, which involved 2,100 to 2,200 Marines from the Fourth Marine 

Corps Provisional Atomic Exercise Brigade. The principal participating units were from the First Marine 

Division of Camp Pendleton, California, and the Third Air Wing from the Marine Corps Air Station at El Toro, 

California.

Originally scheduled to take place during Shot DIABLO, the exercise was rescheduled for Shot HOOD when 

DIABLO misfired. The Marine exercise had several objectives, including the training of personnel in the effects 

and employment of nuclear weapons, the formulation of tactics and techniques relative to nuclear war, and the 

training of personnel in passive defense measures against the effects of nuclear weapons. The post-shot 

troop maneuver involved a coordinated air-ground assault by a reinforced Marine battalion against a military 

objective. After observing the shot, the Marines were transported by helicopters to landing zones near the 

attack objective. A ground assault on the objective, supported by tactical aircraft, was to follow the airlift. 

When the objective was obtained at 11 a.m., more than 6 hours after the shot, some of the troops viewed an 

equipment display area, located from 240 to 2,170 meters from ground zero.

Another 100 project participants took part in 24 scientific tests and 6 operational training projects at Shot 

HOOD. AFSWC activities included the cloud penetration study, as well as such standard support missions as 

cloud sampling, courier missions, cloud tracking, and security sweeps. About 80 AFSWC aircrew took part in 

these activities at HOOD.
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Shot SMOKY was fired from a 700-foot tower in Yucca Flat at 5:30 a.m. on August 31, 1957. The shot had a 

yield of 44 kilotons. At the time of the first survey, the 1 R/h line extended more than 6 kilometers to the 

southeast of ground zero. Exercise Desert Rock troops observed the detonation from a location 13 kilometers 

southwest of ground zero. The closest approach was 4,100 meters west of ground zero. Exercise Desert 

Rock activities at SMOKY included a troop test, the troop observer program, technical service projects, and 

radiological monitoring training. The most significant of these activities, an attack and resupply maneuver, 

involved an estimated 1,150 troops. The initial phase of the project was conducted 2 weeks before the shot. 

Troops prepared defensive positions north and west of SMOKY ground zero for inspection after the shot. The 

troops, a reinforced Infantry Company named Task Force WARRIOR, were part of the 1st Battle Group, 

12th Infantry Regiment, 4th Infantry Division, Fort Lewis, Washington. They observed the shot from assembly 

areas some 13 kilometers from ground zero. Fifteen minutes after the shot, a Pathfinder unit, accompanied by 

radiological monitors, flew into the objective area northwest of ground zero and determined it radiologically 

safe to occupy. At 5:50 a.m., assault elements of the task force had been brought into the objective area. The 

exercise ended at 9:45 a.m. on August 31, 1957.

About 200 additional participants took part in the scientific tests at SMOKY. Another 22 Navy and Air Force 

crewmen participated in operational training projects designed to indoctrinate personnel, practice photographic 

reconnaissance, and test indirect bomb damage assessment equipment and techniques. In addition to 

performing cloud sampling, sample courier returns, security sweeps, and cloud tracking missions, AFSWC 

pilots provided support to Desert Rock, AFSWP, UCRL, and CETG projects. More than 200 AFSWC aircrew 

personnel were involved in these activities.

Shot GALILEO, with a yield of 11 kilotons of explosive energy, was detonated from a 500-foot tower at 

5:40 a.m. on September 2, 1957. At the time of the first survey, fallout of 1 R/h was detected as far as 

2,750 meters northwest of ground zero. Exercise Desert Rock activities at GALILEO, which involved 

300 individuals, included a troop test and two technical service projects. The troop test, conducted by the 

Human Resources Research Office (HumRRO), was to monitor the performance of persons who had 

witnessed a nuclear detonation for the first time.

Immediately after witnessing GALILEO, troops performed a rifle disassembly/assembly to test their reactions. 

They then proceeded to the SMOKY trench area, where they performed the infiltration course test. Film badge 

records suggest that only 110 of the 167 servicemen scheduled to participate actually took part in the troop 

test. Eighty-six of these were test troops, and seven were troop monitors who were to supplement the 

HumRRO monitors who had left early. The remaining 17 probably also assisted in the HumRRO team as 

monitors.

Radiation Doses at Operation PLUMBBOB

Although personnel were continuously film badged during PLUMBBOB, no film badge records have been 

located for the majority of the Marine maneuver troops. Radiation doses have been reconstructed for all of the 

major troop test units at the operation. These doses are in agreement with the available film badge dosimetry. 

About 40 DOD personnel received total doses exceeding 5 rem∗ during PLUMBBOB; half of these were 

accrued by cloud samplers or penetrators. The three largest doses were between 13 and 22 rem to Air Force 

 ∗ A rem is a radiation protection unit of measure that quantifies the risk of biological effects resulting from exposure to 

ionizing radiation. Ionizing radiation is any radiation (gamma, x-ray, beta, neutron, or alpha) capable of displacing 

electrons from atoms or molecules, thereby producing ions. According to the National Council on Radiation Protection 

and Measurements (NCRP, Report No. 160, Table 1.1), the general U.S. population receives about 0.62 rem per year 

from natural background radiation sources (radon, cosmic rays, and rocks) and man-made radiation sources (medical 

diagnostic x-rays and consumer products). As a basis of comparison, a standard diagnostic chest x-ray delivers a 

radiation dose of about 0.02 rem.
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fliers who penetrated the Shot JOHN cloud at about 10 minutes after burst. The other doses over 5 rem were 

scattered, mostly among Desert Rock VII and VIII support and technical service project personnel. Very few of 

the personnel in the major troop test described above received as much as 2 rem. The average total dose to 

DOD participants at PLUMBBOB was 0.4 rem.

The totals of reconstructed and film badge doses for PLUMBBOB participants are depicted below.

For more information on dose reconstruction, see the reports “Analysis of Radiation Exposure, 4th Marine 

Corps Provisional Atomic Exercise Brigade, Exercise Desert Rock VII, Operation PLUMBBOB” (DNA 5774F); 

“Analysis of Radiation Exposure for Task Force WARRIOR, Shot SMOKY, Exercise Desert Rock VII-VIII, 

Operation PLUMBBOB” (DNA 4747F); and “Analysis of Radiation Exposure for Task Force BIG BANG, Shot 

GALILEO, Exercise Desert Rock VII-VIII, Operation PLUMBBOB” (DNA 4772F). Also see the report

“PLUMBBOB Series 1957” (DNA 6005F). These reports are available online at

https://www.dtra.mil/DTRA-Mission/Reference-Documents/NTPR-Info/.

September 2021
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Summary of Operation PLUMBBOB Nuclear Weapons Tests (1957)a

Shotb Sponsor Date Local

Timec Type

Height 

of

Burst (ft)

Yieldd

PROJECT 57 AEC Apr 24 6:27 a.m. PST Surface 0 0

BOLTZMANN LASL May 28 4:55 a.m. PDT Tower 500 12 kt

FRANKLIN LASL Jun 2 4:55 a.m. PDT Tower 300 140 tons

LASSEN UCRL Jun 5 4:45 a.m. PDT Balloon 500 0.5 ton

WILSON UCRL Jun 18 4:55 a.m. PDT Balloon 500 10 kt

PRISCILLA LASL/DOD Jun 24 6:30 a.m. PDT Balloon 700 37 kt

COULOMB A 

Safety Test LASL Jul 1 10:30 a.m. PDT Surface 0 0

HOOD UCRL Jul 5 4:40 a.m. PDT Balloon 1500 74 kt

DIABLO UCRL Jul 15 4:30 a.m. PDT Tower 500 17 kt

JOHN DOD Jul 19 7 a.m. PDT Air to Air 

Missile 18,500 about 2 kt

KEPLER LASL Jul 24 4:50 a.m. PDT Tower 500 10 kt

OWENS UCRL Jul 25 6:30 am. PDT Balloon 500 9.7 kt

PASCAL A 

Safety Test LASL Jul 26 1 a.m. PDT Shaft -500 Slight

STOKES LASL Aug 7 5:25 a.m. PDT Balloon 1500 19 kt

SATURN 

Safety Test UCRL Aug 9 6 p.m. PDT Tunnel -100 zero

SHASTA UCRL Aug 18 5 a.m. PDT Tower 500 17 kt

DOPPLER LASL Aug 23 5:30 a.m. PDT Balloon 1500 11 kt

PASCAL B 

Safety Test LASL Aug 27 3:35 p.m. PDT Shaft -500 slight

FRANKLIN 

PRIME LASL Aug 30 5:40 a.m. PDT Balloon 750 4.7 kt

SMOKY UCRL Aug 31 5:30 a.m. PDT Tower 700 44 kt

GALILEO LASL Sep 2 5:40 a.m. PDT Tower 500 11 kt

WHEELER UCRL Sep 6 5:45 a.m. PDT Balloon 500 197 tons

COULOMB B 

Safety Test LASL Sep 6 1:05 p.m. PDT Surface 0 300 tons

LAPLACE LASL Sep 8 6 a.m. PDT Balloon 750 1 kt

FIZEAU LASL Sep 14 9:45 a.m. PDT Tower 500 11 kt

NEWTON LASL Sep 16 5:50 a.m. PDT Balloon 1500 12 kt

RAINIER UCRL Sep 19 10 a.m. PDT Tunnel -880 1.7 kt

WHITNEY UCRL Sep 23 5:30 a.m. PDT Tower 500 19 kt

CHARLESTON UCRL Sep 28 6 a.m. PDT Balloon 1500 12 kt

MORGAN UCRL Oct 7 5 a.m. PST Balloon 500 8 kt

a Source: United States Nuclear Tests, July 1945 through September 1992, DOE/NV-209 (Rev. 15), Dec 2000.

b Four safety tests (PASCAL C, COULOMB C, VENUS, and URANUS) were conducted at NTS for Project 58 between the 

end of PLUMBBOB testing in October 1957 and the start of HARDTACK II in September 1958. c Pacific Standard Time/Pacific Daylight Time.

d One kiloton (kt) equals the approximate energy release of one thousand tons of TNT.
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