Enewetak Research Articles

The Serendipitous Discovery of the New Elements Einsteinium and Fermium from the Debris of the Mike Thermonuclear Test

On October 31, 1952, the United States successfully detonated the Los Alamos Mike thermonuclear device on the surface of Elugelab Island at Eniwetok Atoll in the Pacific Ocean. This test was the first demonstration of a high-yield thermonuclear explosion on Earth. The 10.4-Mt device yield obliterated Elugelab Island and left a 6240-ft-diameter underwater crater. Later, radiochemical analysis of the explosion debris produced the unanticipated discovery of 15 new heavy transuranic isotopes and two new elements, which were later named einsteinium and fermium. Initially, the discovery of these elements was classified, but in 1955, the results were declassified and announced to the world. The Mike results later led to the development of the Heavy Element and Isotope Effort under the U.S. Plowshare Peaceful Nuclear Explosions Program, under which additional new heavy transuranic isotopes were produced.

Carbonate diagenesis: A celebration of the work of John Anthony Dawson (Tony) Dickson

Carbonate diagenesis: A celebration of the work of John Anthony Dawson (Tony) Dickson

Living through Atomization: Runit Dome, Radioactive Matter, and Poetry of Digestion

Even after a nuclear blast life continues to unfurl its leaves —Kathy Jetñil-Kijiner (“Of Islands and Elders”) In a view from above, a mosaiced gray dome lies amid green low-lying vegetation. Over 377 feet in diameter, this strange concrete object disrupts the beach’s smooth stretch of sandy greenery, not unlike an unidentified flying object that has made a furtive landing. In the surrounding ocean lies a blue hole, nearly identical in size and shape as the dome, like a sibling. Indeed, they are from the same series of nuclear weapons that the United States detonated in the Marshall Islands between 30 June 1946 and 18 August 1958, which included Castle Bravo, a hydrogen bomb approximately a thousand times more devastating than Little Boy, the bomb that destroyed Hiroshima (Walsh and Heine 298). Situated in the Runit Island as a part of the Enewetak Atoll, the disk and the hole function as a visual reminder of the ways in which these detonations permanently altered the environment and its residents.

Constraining diagenesis within shallow water carbonate environments: Insights from clumped and sulfur isotopes

The geochemical records of shallow-water carbonate sediments can be influenced by both meteoric and marine diagenesis, where the contribution from each can be difficult to constrain using traditional δ18O and δ13C values. Here sediment cores from Enewetak Atoll have been utilized as a case study, in which clumped isotope-derived temperatures and calculated δ18Ofluid values are combined with the δ34S values of the carbonate-associated sulfate, to differentiate the types of diagenetic alteration which have influenced the geochemical record, thus providing further insights into the extent and timing of carbonate alteration. While sediments at Enewetak Atoll have undergone repeated periods of subaerial exposure, calculated δ18Ofluid values indicate that the amount of meteoric alteration is reliant on the availability of meteoric fluids, as the presence of exposure surfaces alone does not imply that extensive diagenetic alteration has occurred. Additionally, in the deepest zone of the Enewetak cores, it could be determined that the sediments were initially exposed to meteoric fluids, resulting in partial alteration, and later affected by burial and circulation of deep ocean water, resulting in recrystallization within the section, uniformly overprinting the temperature and δ18Ofluid values. The results of this study indicate that by utilizing systematics such as δ34SCAS, ∆47, and δ18Ofluid values, in addition to the more traditional proxies, a detailed understanding of the diagenetic processes which have altered shallow water sediments can be better constrained, allowing for more accurate interpretations of ancient sedimentary records.

The influence of diagenesis on carbon and oxygen isotope values in shallow water carbonates from the Atlantic and Pacific: Implications for the interpretation of the global carbon cycle

Global correlation of negative excursions in the δ13C values of shallow water carbonates have been used to interpret and identify major environmental changes through geologic time, such as the glaciations of the Neoproterozoic. As a result of their global reproducibility and similar geometry, these signals have predominantly been interpreted as being representative of the original δ13C values of dissolved inorganic carbon in the oceans, which in turn reflect major changes in the global carbon cycle. In this paper δ13C values from cores drilled in Enewetak Atoll (Pacific) and the Great Bahama Bank (Atlantic), are shown as examples of how similarly correlating variations in global δ13C values, can arise from diagenetic processes. It is further shown that while the profiles of the changes in δ13C values may appear synchronous, as a result of varying rates of deposition and subsidence, that the actual timing of the two changes can be quite different. By comparison of the geometry and global correlation of δ13C values measured in this study, it is proposed that the δ13C values of ancient sequences, may have resulted from non-synchronous diagenetic processes, rather than true changes in the global carbon system. This emphasizes the need for precise chronological control when interpreting sediment records, which is not present during many older geological time periods, in order to constrain the origin and correlation of carbon isotope variations.

Initial Strontium-90 concentrations in ocean sediment from the northern Marshall Islands

The United States detonated 67 nuclear weapons in the Marshall Islands from 1946 to 1958. While there has been significant study of the aftereffects of these explosions over the decades that followed, few values of strontium-90 (90Sr) contamination have been reported. Sediment cores from the Bravo test crater in Bikini Atoll and Lacrosse crater near Runit Island (Enewetak Atoll) were assessed for 90Sr and cesium-137 (137Cs) concentrations, which were found to be measurable in all cores. 90Sr values were found to be roughly consistent across the tested cores. Ratios of 90Sr/137Cs are elevated compared to values measured previously at other sites of weapons testing and nuclear accidents. These findings suggest the need to further investigate 90Sr concentrations in the northern Marshall Islands to assess the safety of current residents in light of the potential for 90Sr conveyance and to provide input regarding resettlement of currently unoccupied islands and atolls.

Isotopic signatures of plutonium and uranium at Bikar atoll, northern Marshall Islands

We present plutonium (Pu) and uranium (U) isotopic fingerprints (or signatures) in environmental samples collected at Bikar Atoll. Bikar is the second –most northern atoll of the Republic of the Marshall Islands, and therefore an important reference point to evaluate the extension of the regional fallout from the Pacific Proving Grounds (PPG) in Bikini and Enewetak Atolls. Previous studies have shown that regional fallout from atmospheric nuclear weapon testing (NWT) in Bikini and Enewetak has resulted in elevated levels of fallout radionuclides in this atoll. In order to optimally interpret the isotopic fingerprints, we compare our results with data obtained in eleven certified reference materials, representing different contamination sources. As well as 238Pu, 239Pu, 240Pu, 241Pu, 238U and 235U, this study also encompasses less commonly reported radionuclides such as 242Pu, 244Pu and 236U. We show the importance of combining numerous fingerprints for improved assessment of the source of a nuclear contamination.In samples from Bikar, Pu and U isotope ratios were found to vary within narrow ranges. Pu and U fingerprints suggest that regional fallout from the Castle Bravo test in March 1954 was the main source of the contamination. This was further confirmed by two different age dating approaches that estimated 1954 as the year of the contamination. We demonstrate that use of an exponential function to approximate the yield of heavy radionuclides in thermonuclear explosions with increasing mass is a valid approach for estimating the age of a contamination. We show that, if sufficient radionuclide activity concentration measurement results with low uncertainties are available, this method is robust.

“Post-Quantal Garden” Annotated

The Post-Quantal Garden is a work of speculative fiction based on J.G. Ballard’s short story “The Terminal Beach” first published in 1964. Set within Donna Haraway’s climate-changed Chthulucene, the work is intended as an elliptical rumination on the history of nuclear testing in the Pacific, bio-hacking, tropicality, and apocalyptic narrative. Moving between historical fact and speculative fiction, the story takes the form of a scholarly introduction to and contextualization of fictional passages from an imaginary journal supposedly found during the very real radiological clean-up of Enewetak Atoll. Enewetak, an atoll in the Marshall Islands group, was used by the US for nuclear testing and was the site of operation Ivy-Mike, the first fusion bomb test, and is the setting for Ballard’s Terminal Beach.

America’s Atomic Age: The Health and Environmental Consequences of Governmental Negligence in Nuclear Tests

The first atomic bombs tested and detonated in the United States (US) sparked a mass fascination with atomic technology in a period that came to be known as the Atomic Age. The widespread support of the atomic bombings in World War II (WWII) and approval of atomic weapons thus ignited accelerated testing of atomic weaponry. However, with the earliest nuclear weapons tests, the American military paid little attention to the potential consequences of the tests. This paper examines the nature, impact, and implications of two of the major twentieth-century American atomic tests: Crossroads Baker and Castle Bravo. These tests led to serious health repercussions for both native Bikini Islanders and American servicemen involved with the tests. The American government’s reckless approach to nuclear testing in the first part of the twentieth century was not only disastrous in terms of the health issues it created but was also unethical due to its misleading warnings. The environmental and health effects of the US government’s negligent actions then can still be felt today — nuclear waste from the tests remains locked up with little maintenance at the Enewetak Atoll, threatening another potential nuclear disaster due to mismanagement and negligence.

Lingering radioactivity at the Bikini and Enewetak Atolls

We made an assessment of the levels of radionuclides in the ocean waters, seafloor and groundwater at Bikini and Enewetak Atolls where the US conducted nuclear weapons tests in the 1940's and 50's. This included the first estimates of submarine groundwater discharge (SGD) derived from radium isotopes that can be used here to calculate radionuclide fluxes in to the lagoon waters. While there is significant variability between sites and sample types, levels of plutonium (239,240Pu) remain several orders of magnitude higher in lagoon seawater and sediments than what is found in rest of the world's oceans. In contrast, levels of cesium-137 (137Cs) while relatively elevated in brackish groundwater are only slightly higher in the lagoon water relative to North Pacific surface waters. Of special interest was the Runit dome, a nuclear waste repository created in the 1970's within the Enewetak Atoll. Low seawater ratios of 240Pu/239Pu suggest that this area is the source of about half of the Pu in the Enewetak lagoon water column, yet radium isotopes suggest that SGD from below the dome is not a significant Pu source. SGD fluxes of Pu and Cs at Bikini were also relatively low. Thus radioactivity associated with seafloor sediments remains the largest source and long term repository for radioactive contamination. Overall, Bikini and Enewetak Atolls are an ongoing source of Pu and Cs to the North Pacific, but at annual rates that are orders of magnitude smaller than delivered via close-in fallout to the same area.

Nuclear weapons produced 236U, 239Pu and 240Pu archived in a Porites Lutea coral from Enewetak Atoll

A slice from a Porites Lutea coral core collected inside the Enewetak Atoll lagoon, within 15 km of all major nuclear tests conducted at the atoll, was analysed for 236U, 239Pu and 240Pu over the time interval 1952-1964 using a higher time resolution than previously reported for a parallel slice from the same core. In addition two sediment samples from the Koa and Oak craters were analysed. The strong peaks in the concentrations of 236U and 239Pu in the testing years are confirmed to be considerably wider than the flushing time of the lagoon. This is likely due to the growth mechanism of the coral. Following the last test in 1958 atom concentrations of both 236U and 239Pu decreased from their peak values by more than 95% and showed a seasonal signal thereafter. Between 1959 and 1964 the weighted average of the 240Pu/239Pu atom ratio is 0.124 ± 0.008 which is similar to that in the lagoon sediments (0.129 ± 0.006) but quite distinct from the global fallout value of ∼0.18. This, and the high 239,240Pu and 236U concentrations in the sediments, provides clear evidence that the post-testing signal in the coral is dominated by remobilisation of the isotopes from the lagoon sediments rather than from global fallout.

Space: The Final Frontier-Research Relevant to Mars.

A critically important gap in knowledge surrounds the health consequences of exposure to radiation received gradually over time. Much is known about the health effects of brief high-dose exposures, such as from the atomic bombings in Japan, but the concerns today focus on the frequent low-dose exposures received by members of the public, workers, and, as addressed in this paper, astronauts. Additional guidance is needed by the National Aeronautics and Space Administration (NASA) for planning long-term missions where the rate of radiation exposure is gradual over years and the cumulative amounts high. The direct study of low doses and low-dose rates is of immeasurable value in understanding the possible range of health effects from gradual exposures and in providing guidance for radiation protection, not only of workers and the public but also astronauts. The ongoing Million Person Study (MPS) is 10 times larger than the study of the Japanese atomic bomb survivors of 86,000 survivors with estimated doses. The number of workers with >100 mSv career dose is substantially greater. The large study size, broad range of doses, and long follow-up indicate substantial statistical ability to quantify the risk of exposures that are received gradually over time. The study consists of 360,000 U.S. Department of Energy workers from the Manhattan Project; 150,000 nuclear utility workers from the inception of the nuclear age; 115,000 atomic veterans who participated in above-ground atmospheric tests at the Nevada Test Site and the Bikini and Enewetak Atolls and Johnston Island in the Pacific Proving Grounds (PPG); 250,000 radiologists and medical workers; and 130,000 industrial radiographers. NASA uses an individual risk-based system for radiation protection in contrast to the system of dose limits for occupational exposures used by terrestrial-based organizations. The permissible career exposure limit set by NASA for each astronaut is a 3% risk of exposure-induced death (REID) from cancer at a 95% confidence level to account for uncertainties in risk projections. The large size of the MPS will reduce the uncertainty in the risk estimates, narrowing the 95% confidence interval, and thus allow more time in space for astronauts. Further differences between men and women in their response to radiation can be more fully examined, and non-cancer outcomes, such as neurological disorders and cardiovascular disease, can be evaluated in a way not hitherto possible.

Offshoring American Environmental Law: Land, Culture, and Marshall Islanders’ Struggles for Self-Determination During the 1970s

This article explores the impact of environmental law in US-controlled Micronesia. Historians have suggested that US environmental legislation and legal activism during the 1960s and 1970s often overlooked issues of environmental racism and injustice. This article establishes the importance of these emerging environmental laws for Marshall Islanders living under American rule and subjected to the harms of nuclear weapons testing. In 1972 the displaced people of Enewetak Atoll—a former nuclear test site—sued the United States hoping to stop a new program of conventional weapons testing on their badly contaminated ancestral atoll. The capacious concept of the environment used in the National Environmental Policy Act of 1969 and the statute’s ambiguous territorial reach offered islanders important new opportunities to articulate their environmental values and to further their struggles for self-determination over ancestral lands and waters. This article argues that environmental law transcended the artificial territorial boundaries between the United States and its Pacific dependencies, opening up an important new venue of negotiation and conflict over the scope and environmental footprint of US offshore power.

Time-resolved record of 236U and 239,240Pu isotopes from a coral growing during the nuclear testing program at Enewetak Atoll (Marshall Islands)

A comprehensive series of nuclear tests were carried out by the United States at Enewetak Atoll in the Marshall Islands, especially between 1952 and 1958. A Porites Lutea coral that was growing in the Enewetak lagoon within a few km of all of the high-yield tests contains a continuous record of isotopes, which are of interest (e.g. 14C, 236U, 239,240Pu) through the testing period. Prior to the present work, 14C measurements at ∼2-month resolution had shown pronounced peaks in the Δ14C data that coincided with the times at which tests were conducted. Here we report measurements of 236U and 239,240Pu on the same coral using accelerator mass spectrometry, and again find prominent peaks in the concentrations of these isotopes that closely follow those in 14C. Consistent with the 14C data, the magnitudes of these peaks do not, however, correlate well with the explosive yields of the corresponding tests, indicating that smaller tests probably contributed disproportionately to the debris that fell in the lagoon. Additional information about the different tests can also be obtained from the 236U/239Pu and 240Pu/239Pu ratios, which are found to vary dramatically over the testing period. In particular, the first thermonuclear test, Ivy-Mike, has characteristic 236U/239Pu and 240Pu/239Pu signatures which are diagnostic of the first arrival of nuclear test material in various archives.

Bomb‐produced radiocarbon in the western tropical Pacific Ocean: Guam coral reveals operation‐specific signals from the Pacific Proving Grounds

AbstractHigh‐resolution radiocarbon (14C) analyses on a coral core extracted from Guam, a western tropical Pacific island, revealed a series of early bomb‐produced 14C spikes. The typical marine bomb 14C signal—phase lagged and attenuated relative to atmospheric records—is present in the coral and is consistent with other regional coral records. However, 14C levels well above what can be attributed to air‐sea diffusion alone punctuate this pattern. This anomaly was observed in other Indo‐Pacific coral records, but the Guam record is unmatched in magnitude and temporal resolution. The Guam coral Δ14C record provided three spikes in 1954–1955, 1956–1957, and 1958–1959 that are superimposed on a normal 14C record. Relative to mean prebomb levels, the first peak rises an incredible ∼700‰ and remained elevated for ∼1.2 years. A follow up assay with finer resolution increased the peak by ∼300‰. Subsequent spikes were less intense with a rise of ∼35 and ∼70‰. Each can be linked to thermonuclear testing in the Pacific Proving Grounds at Bikini and Enewetak atolls in Operations Castle (1954), Redwing (1956), and Hardtack I (1958). These 14C signals can be explained by vaporization of coral reef material in the nuclear fireball, coupled with neutron activation of atmospheric nitrogen (14C production), and subsequent absorption of 14CO2 to form particulate carbonates of close‐in fallout. The lag time in reaching Guam and other coral records abroad was tied to ocean surface currents and modeling provided validation of 14C arrival observations.

Chromosome aberrations in Japanese fishermen exposed to fallout radiation 420-1200km distant from the nuclear explosion test site at Bikini Atoll: report 60years after the incident.

During the period from March to May, 1954, the USA conducted six nuclear weapon tests at the "Bravo" detonation sites at the Bikini and Enewetak Atolls, Marshall Islands. At that time, the crew of tuna fishing boats and cargo ships that were operating approximately 150-1200km away from the test sites were exposed to radioactive fallout. The crew of the fishing boats and those on cargo ships except the "5th Fukuryu-maru" did not undergo any health examinations at the time of the incident. In the present study, chromosome aberrations in peripheral blood lymphocytes were examined in detail by the G-banding method in 17 crew members from 8 fishing boats and 2 from one cargo ship, 60years after the tests. None of the subjects examined had suffered from cancer. The percentages of both stable-type aberrations such as translocation, inversion and deletion, and unstable-type aberrations such as dicentric and centric ring in the study group were significantly higher (1.4- and 2.3-fold, respectively) than those in nine age-matched controls. In the exposed and control groups, the percentages of stable-type aberrations were 3.35% and 2.45%, respectively, and the numbers of dicentric and centric ring chromosomes per 100 cells were 0.35 and 0.15, respectively. Small clones were observed in three members of the exposed group. These results suggest that the crews were exposed to slightly higher levels of fallout than had hitherto been assumed.

Late Cenozoic sea level and the rise of modern rimmed atolls

Sea-level records from atolls, potentially spanning the Cenozoic, have been largely overlooked, in part because the processes that control atoll form (reef accretion, carbonate dissolution, sediment transport, vertical motion) are complex and, for many islands, unconstrained on million-year timescales. Here we combine existing observations of atoll morphology and corelog stratigraphy from Enewetak Atoll with a numerical model to (1) constrain the relative rates of subsidence, dissolution and sedimentation that have shaped modern Pacific atolls and (2) construct a record of sea level over the past 8.5millionyears. Both the stratigraphy from Enewetak Atoll (constrained by a subsidence rate of ~20m/Myr) and our numerical modeling results suggest that low sea levels (50–125m below present), and presumably bi-polar glaciations, occurred throughout much of the late Miocene, preceding the warmer climate of the Pliocene, when sea level was higher than present. Carbonate dissolution through the subsequent sea-level fall that accompanied the onset of large glacial cycles in the late Pliocene, along with rapid highstand constructional reef growth, likely drove development of the rimmed atoll morphology we see today.

Grids & Datums

Little is clearly understood about the prehistory of the Marshall Islands. Researchers * agree on little more than that successive waves of migratory people from Southeast Asia spread across the Western Pacific about 3,000 years ago and that some of them landed on and remained on these islands. The Spanish explorer de Saavedra landed there in 1529. They were named for English explorer John Marshall, who visited them in 1799. The Marshall Islands were claimed by Spain in 1874. Germany established a protectorate in 1885 and set up trading stations on the islands of Jaluit and Ebon to carry out the flourishing copra (dried coconut meat) trade. Marshallese iroij (high chiefs) continued to rule under indirect colonial German administration. At the beginning of World War I, Japan assumed control of the Marshall Islands. Their headquarters remained at the German center of administration, Jaluit. U.S. Marines and Army troops took control from the Japanese in early 1944, following intense fighting on Kwajalein and Enewetak atolls. In 1947, the United States, as the occupying power, entered into an agreement with the UN Security Council to administer Micronesia, including the Marshall Islands, as the Trust Territory of the Pacific Islands. On May 1, 1979, in recognition of the evolving political status of the Marshall Islands, the United States recognized the constitution of the Marshall Islands and the establishment of the Government of the Republic of the Marshall Islands. The constitution incorporates both American and British constitutional concepts (Background Notes, U.S. Dept. of State, 2014).

Harold Melvin Agnew

Harold Melvin Agnew, a member of the Manhattan Project who was the third director of Los Alamos National Laboratory and a presidential science adviser, succumbed to chronic lymphocytic leukemia on 29 September 2013 at his home in Solana Beach, California.Agnew was born on 28 March 1921 in Denver, Colorado. He won a scholarship to the University of Denver, where he studied chemistry, was a lifeguard, and met his future wife, Beverly, who later served as a secretary to J. Robert Oppenheimer.Harold Melvin AgnewLOS ALAMOS NATIONAL LABORATORY ARCHIVESPPT|High resolutionAfter receiving his undergraduate degree in chemistry in mid 1942, Agnew was recruited for the Manhattan Project. In his new role, he helped build the world’s first nuclear reactor at the University of Chicago under the direction of his mentor, Enrico Fermi. On 2 December 1942, Agnew was a witness to the first self-sustaining nuclear chain reaction.Soon after, both Agnew and Fermi joined the staff at Los Alamos. Among other contributions, Agnew helped design the diagnostic canisters that would be used to measure the yield of the atomic strikes against Japan. He witnessed the attack on Hiroshima and, on his own initiative, filmed the detonation. Later in his life, Agnew regularly gave lectures and interviews and never had any regrets about the use of the atomic bombs. He felt that the use of nuclear weapons was imperative to end the war as soon as possible and to stop the carnage that was taking place.After World War II ended, Agnew went back to the University of Chicago to complete his MS and PhD in physics under Fermi. He finished his thesis, “The beta spectra of Cs137, Y91, Chlorine147, Ru106, Sm151, P32, Tm170,” in 1949 and upon graduating returned to Los Alamos, where he performed nuclear-physics research. He quickly concluded that he could contribute more to the nuclear weapons program in the areas of design and development.Agnew made significant contributions to the physics understanding of the first thermonuclear device, which was successfully tested in November 1952 at Enewetak Atoll. He went on to become a leader of major tests of next-generation devices that were fired in Operation Castle in 1954.By the early 1960s, his talents were well known in the defense community. He was invited to be the scientific adviser to two successive commanders of NATO.After returning to Los Alamos in 1964, Agnew increased substantially the laboratory’s interactions with the Department of Defense. In addition, he successfully developed a wide range of contacts from among the diplomatic and military rosters of the NATO allies.During his time as a NATO adviser, Agnew recognized the need for enhanced nuclear weapons security. Ultimately, he led the Los Alamos effort to develop the permissive action link. A joint project with Sandia National Laboratories, PAL technology ensures that nuclear weapons cannot be detonated without proper authorization. For decades, PALs have been a standard feature on US nuclear weapons.By the time Norris Bradbury, the second director of Los Alamos, stepped down in 1970, Agnew was clearly a leading nuclear weapons authority in the free world. As long as Los Alamos held a major role in nuclear weapons, he was the obvious choice to lead the laboratory into the future.Agnew served as director of Los Alamos for almost a decade and brought into fruition optimum weapons for the deterrent posture that had developed during the 1960s. He also introduced technical diversity to the lab. Until Agnew became director, virtually every program was tied, directly or indirectly, to weapons work. The multidisciplinary laboratory of today was created by Agnew in the 1970s.After retiring as Los Alamos director in 1979, Agnew became president and CEO of General Atomics. In that position, which he held until 1985, he pushed for the development of safe reactor technologies and was a vocal advocate for nuclear power. Throughout the 1980s he also was a presidential science adviser to Ronald Reagan.Agnew liked to say that the US nuclear deterrent was his legacy. That is an assessment in which we wholeheartedly concur. No other individual held so much responsibility over so many decades for the creation of the stockpile. Through his contributions as a nuclear scientist and adviser, Agnew charted a path that has ultimately contributed to a more stable and sustainable world.© 2014 American Institute of Physics.

1932, a watershed year in nuclear physics

The consequences, for good and ill, of that annus mirabilis of discovery and invention are still very much with us.