Nuclear Weapons Testing at Bikini Atoll

Ethan Sperla
March 22, 2022

Submitted as coursework for PH241, Stanford University, Winter 2021


Fig. 1: A colorized photo of the "Baker" explosion on July 25, 1946. (Source: Wikimedia Commons)

The Bikini Atoll is a coral reef consisting of 23 islands within the Northern edge of the Marshall Islands. [1] In 1946, the United States government began relocating native Bikini Islanders before using it and surrounding atolls for nuclear weapons testing for 12 years. [2] The resulting geographic destruction and radiation have had lasting repercussions on the ecosystem and people that once called the islands home. Even though efforts have been made to correct the consequence of nuclear weapons testing, there remains a need to do more. For that reason, it remains important to study the history of Bikini Atoll and the effects of the nuclear weapons testing that occurred there.


Micronesian settlers first arrived over 2000 years ago at the Marshall Islands, which includes 30 atolls and over 1150 islands. [3] However, because of their remote location, the settlers did not have contact with the outside world until the Spanish spotted them in 1525. [3] The settlers of Bikini Atoll remained isolated due to the atoll's location. Later, during World War I, the Marshall Islands were captured by the Empire of Japan. [3]

The islands were left alone until the beginning of World War II when the islands became a strategic stronghold for the Japanese. The Marshall Islands remained out of the conflict until the Battle of Kwajalein in February 1944, when the United States successfully captured the island. [3] The battle was seen as a significant moral victory to the United States and a warning to the Japanese to better prepare for American offensives and invasions.

After World War II, the United States wanted a remote area with accessible ports and land for installations to test nuclear weapons. The Bikini Atoll was selected to be the Atomic Energy Commissions Pacific Proving Ground. [4] Permission to relocate the atoll's inhabitants was granted to the United States by the Bikini chief to test nuclear weapons for "the benefit of mankind." [3]

Testing on an Atomic Scale

From 1946 to 1958, the Marshall Islands would undergo 67 nuclear detonations throughout its lifespan as the Pacific Proving Ground. [5] In July of 1946, the United States conducted two atomic weapons tests at Bikini, the world's first detonations after World War II. [2] One of these first tests, Test Baker, is shown in Fig. 1. However, it was not until 1947 that the United Nations designated the United States as the administrator of territory, including the Marshall Islands. [2] An additional 44 nuclear devices were exploded near another atoll within the Marshall Islands when it replaced Bikini as the test site between 1948 and 1954. [5] Bikini Atoll was reactivated as a test site in 1954 until the United States ended nuclear weapon testing in the Marshall Islands in 1958. [1] It was subjected to 23 nuclear detonations between 1946 to 1948 and 1954 to 1958. [2] All but one test was conducted when the prevailing winds were thought to carry the atomic fallout out to sea. [6]

In late April of 1954, the winds shifted days before a test. [6] However, despite an extensive radiological safety program whose objectives included protecting inhabited islands from contamination, officials still decided to proceed with a test even though fallout was likely to pass over the inhabited Rongelap and Utrik atolls. [2] So, on March 1st, 1954, Castle Bravo was detonated over Bikini Atoll and exhibited the strength of 15 million tons of TNT. [4] Fig. 2 shows the nuclear blast of Castle Bravo. It was the first of many high-yield thermonuclear design tests conducted by the United States. [4]

Fig. 2: A color photo of the "Castle Bravo" explosion on March 1, 1954. (Source: Wikimedia Commons)

Lasting Impacts

As expected, the nuclear tests would have lasting effects on the Bikini Atoll, surrounding atolls, and the people who called them home. Individuals removed from Bikini Atoll in 1946 were moved between other atolls and an island while their permanent home had yet to be determined. [2] In 1948, the Bikini people were relocated to a small and isolated island owned by the United States Trust Territory. [2] However, the native islanders still underwent significant hardships.

The people of Rongelap Atoll had a similar experience. Gray ash, known as nuclear fallout, began falling a few hours following Castle Bravo on Rongelap Atoll, some 100 miles west of Bikini. [6] Fig. 3 shows a topographical map illustrating the spread of nuclear fallout. Rongelaps 85 inhabitants were quickly evacuated after they began to bleed, vomit, and lose their hair. [6] Like the people of Bikini, United States officials moved them from island to island. [6] Doctors and scientists would sometimes take young children to Hawaii to have their thyroids removed to protect them from developing thyroid cancer. [6] Deformed babies were born, and cancers of all types developed in the years and decades following relocation. [6]

In 1968, President Lyndon Johnson stated it was safe for the native islanders to return to Rongelap and Bikini. [6] Scientists had measured a return to normal levels in background radiation. [6] However, the decision was made preemptively. [6] Doctors ordered the second evacuation of Bikini in 1978 after discovering that high levels of cesium 137, a radioactive isotope, remained in the soil and eventually entered the food chain and people. [6] The people of Rongelap were told that evacuation was unnecessary by the United States government regardless of mounting evidence suggesting that they were experiencing something similar to Bikinians. [6]

Fig. 3: Illustration of the nuclear fallout pattern on the Marshall Islands and surrounding area following the "Castle Bravo" explosion on March 1, 1954. [9] (Source: Wikimedia Commons)

Since then, the native islanders have sued the United States government several times for damages and the cost of making their islands inhabitable again. [6] In 1986, when the Marshall Islands gained its independence from the United States, the United States government provided a one-time settlement for past, present, and future damages experienced due to the nuclear weapons testing program from 1946 to 1958. [7] The Marshall Islands Nuclear Claims Tribunal was established to render final determination upon all claims of damages. [7]

While the United States allocated a $150 million trust fund to compensate the inhabitants of the Marshall Islands in 1986, it pales in comparison to the approved compensation of $562 million as of January 2003 for persons injured due to nuclear tests in Nevada. [8] The tests in Nevada were much smaller in number and magnitude relative to those administered in the Marshall Islands. [8]


It is essential to acknowledge the Marshall Islands' rich history and culture existed before they were involved in testing United States nuclear weapons. However, now it is time to reconcile with the role of Bikini Atoll and other surrounding atolls as part of the Atomic Energy Commissions Pacific Proving Ground. The story of the native islanders must be told and remembered in conjunction with the geographic destruction and radioactive contamination caused by nuclear weapons detonations and fallout. The resources allocated by the United States for the resulting damages do not go far enough to help those most affected.

© Ethan Sperla. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.


[1] P. Stegnar, "Review at Bikini Atoll," International Atomic Energy Agency, IAEA Bull. 40, No. 4, 15 (December 1998).

[2] J. Niedenthal, "A History of the People of Bikini Following Nuclear Weapons Testing in the Marshall Islands: With Recollections and Views of Elders of Bikini Atoll," Health Phys. 73, 28 (1997).

[3] "Marshall Islands," University of Prince Edward Island, 2007.

[4] "Castle Series, 1954," Defense Nuclear Agency, DNA-6035F, April 1982.

[5] "Nuclear Testing Program in the Marshall Islands," United States Senate, S. HRG. 109-178, July 2005.

[6] C. Woodward, "You Can't Go Home Again," Bull. Atom. Sci. 54, No. 5, 10 (1998).

[7] H. M. Barker and B. Rose, "Seeking Compensation for Radiation Survivors in the Marshall Islands: The Contribution of Anthropology," Cult. Survival Quart. 24, No. 1, 48 (2000).

[8] D. Thornburgh et al., "The Nuclear Claims Tribunal of the Republic of the Marshall Islands: An Independent Examination and Assessment of its Decision-Making Processes," Kirkpatrick and Lockhart LLP, January 2003.

[9] T. Kunkle and B. Ristvet, "Castle Bravo: Fifty Years of Legend and Lore," U.S. Defense Threat Reduction Agency, DITRAC SER-12-001, January 2013.