Marshall Islands
From 1946 to 1958, the U.S. conducted atmospheric nuclear tests to evaluate blast effects and refine weapon design, including 67 tests in the Marshall Islands, which is located in the Pacific Ocean, halfway between Hawaii and Australia. The Marshall Islands consists of 5 islands and 29 coral atolls, and the site was selected due to its stable weather conditions, remote location, and low number of inhabitants to locate. In the decades since, scientists have conducted environmental monitoring. In addition, they assess exposures to the lingering effects of fallout contamination of resettled and resettling populations, as well as field workers engaged in ecosystem remediation.
For more than three decades, LLNL researchers have leveraged CAMS resources to support the Marshall Islands Dose Assessment and Radioecology Program. We help determine levels and distributions of fallout radionuclides on land and in atoll lagoons, which present hazards to individuals who may be exposed by breathing air, drinking water, or eating food. Our research findings help local officials advise displaced individuals regarding the possibility of future resettlement, while also providing insight to resettlement workers in the area.
For example, AMS measurements offer a way to accurately assess human exposure to plutonium. LLNL scientists developed a highly sensitive technique that enables us to analyze urine samples that are converted into a powder. We use the technique to count the number of plutonium atoms in each sample. This data enables researchers to track and monitor potential long-term changes in exposure, including exposure associated with remediation activities or changing land-use patterns.
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Fukushima nuclear accident
In March 2011, a 9.0 Richter-scale earthquake and a subsequent tsunami caused severe damage to the Fukushima Daiichi nuclear power plant, located on Japan’s eastern coast, which caused the release of radioactive contamination into the environment. Immediately following the disaster, LLNL’s National Atmospheric Release Advisory Center (NARAC) started providing predictions regarding potential radiation and dose levels near the site. In the weeks that followed, LLNL researchers helped measure environmental radiation levels in the rest of Japan and in other locations, as contamination spread in the air, ocean, and on land. The aim of this research was to better understand human exposure to the radiation, including the impact on plant and animal food supplies.
For example, CAMS researchers measured the presence of iodine-129, a radioactive element with an extremely long half-life that was released by the Fukushima nuclear accident. We analyzed seawater samples collected by scientists onboard ships, from a variety of locations in the Pacific Ocean, between 18 and 375 miles east of Fukushima, during May and June, 2011. In addition, we compared these results with an analysis of seawater samples from the same area collected prior to the disaster.
This analysis helped scientists better understand the movement of radioactive elements released by the Fukushima nuclear accident, including ocean transport and mixing processes. In addition, it helped researchers determine that the radionuclides found in the seawater samples were released directly into the ocean by the power plant, rather than being initially dispersed into the atmosphere and then falling into the ocean. By characterizing the initial source term, scientists will be able to use iodine-129 as a conservative tracer for mapping ocean circulation patterns for decades in the future.
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