Operation IVY

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 IVY was an atmospheric nuclear test series held in the Atomic Energy Commission’s (AEC) Pacific 

Proving Ground at Enewetak Atoll in the Marshall Islands from November 1 to December 31, 1952. The series 

consisted of the two detonations listed below.

Summary of Operation IVY Nuclear Weapons Tests (1952)a

Shot Local 

Date Location Yieldb

MIKE Nov 1 Eluklab Island; surface 10.4 megatons

KING Nov 16 Airburst (1,480 feet 440 meters) over reef 

off Runit Island

500 kilotons

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

b One kiloton equals the approximate energy release of one thousand tons of TNT; one megaton equals the approximate 

energy release of one million tons of TNT.

Historical Background

The U.S. Government decided to pursue the development of thermonuclear weapons in 1950, and the IVY 

series was a key step in this development. MIKE was an experimental device and produced the first 

thermonuclear detonation in which a substantial portion of its energy was generated by the fusion, or joining, of 

hydrogen atoms. KING was a stockpile weapon modified to produce a large yield. It was dropped from a B-36 

bomber. The energy from KING was generated by the fission, or splitting, of plutonium atoms. These were the 

largest yield nuclear detonations at that time.

Joint Task Force 132 (JTF 132) was the organization that conducted the IVY test series. Elements of the four 

services, the AEC and other federal government agencies, and civilians from government laboratory 

organizations and contractors made up this organization. Commander JTF 132 reported to the Joint Chiefs of 

Staff, but was also designated the AEC's agent in conducting the tests. The joint nature of this test 

organization resulted from the requirements of the Atomic Energy Act of 1946. This legislation placed atomic 

energy development under civilian control; however, the remoteness of the IVY series test site required a 

military organization for physical security and technical and logistical support.

The total number of personnel involved in the task force was approximately 14,000, primarily military service 

personnel. Most of these personnel operated from Enewetak Atoll and from task force ships that were based 
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there. Most of the remaining participants were Air Force personnel based at Kwajalein, 360 nautical miles 

(667 kilometers) southeast of Enewetak.

Radiation Protection Standards

The safety of the task force personnel conducting the test series was an important factor in planning the 

conduct of the tests. Pretest measures taken to ensure the safety of personnel were:

1. Modification of ships and aircraft, including the installation of “washdown” systems aboard ships to 

prevent radioactive fallout accumulation and the installation of filters on aircraft pressurization systems 

to prevent radioactive particles from entering aircraft.

2. Design of special protective clothing, including a leadcloth shroud for aircraft pilots operating near the 

radioactive cloud.

3. A training program in radiation safety procedures.

4. The establishment of a technical support unit whose responsibility was to provide the task force with 

expert assistance in radiation safety, including monitoring of radiation, decontamination of personnel, 

laboratory support, maintenance of exposure records, and maintenance and calibration of radiation 

detection equipment.

5. The establishment of a meteorology group whose responsibility was to predict the direction of the winds 

aloft to avoid conducting the tests during times when radioactive fallout might be carried in the direction 

of the task force or inhabited islands.

6. The establishment of a program for the evacuation of all personnel from Enewetak Atoll for the MIKE 

test and the preparation of plans for emergency evacuation of task force personnel from Bikini and 

Kwajalein. Marshall Islanders living at Ujelang were placed aboard a Navy ship just before the MIKE 

detonation in readiness for movement to safety if the fallout moved to the southwest.

7. The establishment of procedures for issuing film badges to individuals whose activities might expose 

them to nuclear radiation so that exposure records could be kept. About 2,000 of the task force 

personnel received these badges.

Radiation Doses at Operation IVY

The IVY dose limit of 3.9 rem∗ was exceeded in only two situations. The seven-man crew in an amphibious 

plane that flew to the rescue of a downed pilot received doses between 10 and 17.8 rem. The highest dose for 

the crew of a photographic plane caught in the fallout was 11.6 rem.

Of the approximately 14,000 participants, only about 2,000 of the task force personnel received film badges. 

The intent of the badging program was to issue badges only to those personnel who might enter contaminated 

areas or be exposed to fallout. Therefore, the low-level fallout on the islands was not, for most personnel, 

 ∗ 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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measured by film badges. The reconstructed doses, however, for all individuals who stayed on the residence 

islands or aboard ships throughout IVY is less than 0.1 rem.

The totals of reconstructed and film badge doses for IVY participants are depicted below. Nearly 99 percent of 

the task force received less than 1 rem as their total dose.

Reconstructed doses for typical shipboard and land-based personnel are derived in the report “Analysis of 

Radiation Exposure for Naval Personnel at Operation IVY” (DNA-TR-82-98). Also see the report “Operation 

IVY 1952” (DNA 6036F). These reports are available online at 

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

September 2021