Beck and Co-Workers Explained:

Accounting for Unfissioned Plutonium from the Trinity Atomic Bomb Test.

Reference: Beck, H. L., Simon, S. L., Bouville, A., & Romanyukha, A. (2020). Accounting for Unfissioned Plutonium from the Trinity Atomic Bomb Test. Health Physics119(4), 504–516.


What was the research question?

Trinity, the first nuclear test ever undertaken, is known to have had limitations in its design which resulted in a low efficiency in transforming plutonium into a nuclear explosion. This had the effect of a larger than expected amount of plutonium failing to undergo nuclear fission and becoming part of the nuclear fallout. The researchers of this paper sought to estimate the amount, the distribution, and the health implications of this unfissioned plutonium within the state of New Mexico.

What did the research involve?

The researchers used a combination of soil measurements collected over many years after the test and mathematical models to make estimates of the geographic distribution of the unfissioned plutonium across the state.

What did they find?

The researchers estimate that about 80% of the unfissioned plutonium would have been deposited within the state of New Mexico and that the majority of this would have been in a relatively small area downwind from the test site. They calculated that the concentration of plutonium residing in the topmost layer of soil meaning it had potential to contaminate persons, was lower than the 1977 US regulatory “action” level for health protection, even in those higher deposition areas.

How did the researchers interpret their basic results?

The researchers concluded that the original amounts deposited at each location were less than levels normally considered as requiring remediation by official bodies and were accordingly, not likely to have caused significant health risks to the local population. They go on to highlight that because levels are currently about 30% of that immediately after the detonation, the plutonium present today is less of a hazard than decades ago.

Who did this research?

This study was done by a team of scientists from the US Department of Energy, U.S. National Cancer Institute and the University of Wollongong, Australia. This research was funded by the U.S. National Cancer Institute, the U.S. National Institute of Allergy and Infectious Diseases and the U.S. National Institutes of Health.

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Supporting Resources

Key Messages

Unfissioned plutonium was deposited within New Mexico state after the Trinity test.

Although manmade, the levels of contamination were below action levels for health protection.

Plutonium fallout from Trinity unlikely to have caused significant health effects.


Links to the research paper

This is a peer-reviewed study meaning that other scientists have reviewed this work before the authors published it in the journal Health Physics in 2020.