Environmental impacts of underground nuclear weapons testing

ABSTRACT

Each nuclear weapon test contributes to a global burden of released radioactivity. Between 1945 and 1996, more than 2,000 nuclear tests were conducted, three-quarters of which were underground. Underground nuclear tests involved placing the nuclear device in a cavity drilled or excavated beneath the surface. The goal was to contain the explosion and its effects to the immediate vicinity of the detonation point, ultimately minimizing the release of radioactive materials into the atmosphere. While these tests successfully curtailed the atmospheric release and radioactive fallout, they created dynamic responses within crustal formations caused by local shock waves from the explosion. This paper discusses the legacy of underground nuclear testing, addressing issues from containment failure to the phenomenological effects after underground detonations and the pathways of subsequent dispersal of radionuclides to the environment.

KEYWORDS:

• Underground nuclear tests
• nuclear weapons
• geological formations
• radionuclides
• groundwater contamination

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1. The number of US nuclear tests reported in different publications ranges from 1051 to 1151. The discrepancy is attributed to the different ways of counting nuclear tests (e.g., the frequency, timing, and the number of nuclear devices). Here, underground nuclear tests refer to one or more nuclear devices in the same tunnel or hole. If we count simultaneous tests or explosions close in time, the number of US tests would be higher than reported here.

2. The scaled depth of burial (empirical measure of blast energy confinement) can be calculated using the equation (McEwan 1988):

$\mathit{scaled}\mathit{depth}\mathit{of}\mathit{burial}=\frac{\mathit{depth}\mathit{of}\mathit{burial}}{\mathit{yield}{\left(\mathit{kt}\right)}^{1/3}}$

3. Assuming the cavity reaches a maximum volume when the gas pressure reaches the lithostatic (overburden) pressure at the explosion depth, the radius of cavity can be estimated using the following equation:

$\frac{\mathit{radius}}{\mathit{yiel}{\mathit{d}}^{1/3}}=\frac{\mathit{medium}\mathit{coefficient}}{{\left(\mathit{density}\times \mathit{gravitational}\mathit{constant}\times \mathit{explosion}\mathit{depth}\right)}^{1/3\gamma }}$

where yield is expressed in kt, and γ is the effective adiabat exponent of the explosion products, which depends on the composition of the emplacement medium (Allen and Duff 1969; Boardman, Rabb, and McArthur 1964; Adushkin and Spivak 2015).

4. Continuous daily intake of 100 picocuries of iodine 131 per day for one year remains within the radiation protection guide’s limit of 0.5 millirems per year. The highest estimated thyroid exposure from inhalation and milk ingestion was 130 millirems, measured in a two-year-old child in Beatty, an unincorporated community bordering the Nevada Test Site.

Additional information

Notes on contributors

Sulgiye Park

Sulgiye Park is a senior scientist with the Global Security Program at the Union of Concerned Scientists. Park holds a PhD in Geological Sciences from Stanford University.

Rodney C. Ewing

Rodney C. Ewing is a Senior Fellow in the Center for International Security and Cooperation in the Freeman Spogli Institute for International Studies and a professor in the Department of Earth and Planetary Sciences in the Stanford Doerr School of Sustainability.