30th Anniversary of Divider

It’s a blast from the past in more ways than one.

October 10, 2023

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As part of a temporary display in the Los Alamos National Lab headquarters building, staff had the opportunity to see legacy items—photos, maps, documents, clothing, and a test rack replica—from the Lab’s weapons testing era.

The display, curated by the National Security Research Center (NSRC), commemorated Divider, which was the nation’s last nuclear test prior to the 1992 moratorium on explosive testing. It was conducted on September 23, 1992, at the Nevada Test Site (now the Nevada National Security Site, or NNSS). Like The Gadget at the Trinity test, which was the world’s first successful detonation of a nuclear device, the Divider test device was a Los Alamos–designed weapon. This was the nation’s 1,054th nuclear test over a 47-year period.

“The items on display are unclassified, but are either housed in a library where browsing is regulated or are personal items that belong to retired weapons scientists,” said Laura McGuiness, a librarian with the NSRC, the Lab’s classified library. “So, this is a chance for Lab staff to freely view a few unique artifacts during a milestone anniversary for the Lab’s weapons history.” 

McGuiness led the effort to research and select from the thousands of Divider-related materials in the NSRC’s collections, which include both classified materials and unclassified historical items.

“I wanted the artifacts displayed to showcase the amount of effort expended to ensure the success of a nuclear test,” McGuiness said. “My favorite item is the Divider participant roster, precisely because it revealed the extraordinary level of teamwork required.”


Here are a few highlights from the Divider 

30th Anniversary display: 

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Test logos

All 1,054 U.S. nuclear tests have unique names. Tests were named after birds, colors, games, trees, and even cities in Texas. By the 1960s, logos featuring test names appeared as stickers, patches, and artwork on test towers. The logo for Divider was created by Ward Zaelke and features a caricature of the draftsman Larry Smith holding a divider—a common drawing tool. 

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Diagnostic drawing of Icecap test rack and tower, illustrating tower height and drill depth. 

Photos, drawings

Dozens of pre-test preparation photos from 1992 and present-day images of the Divider crater were displayed alongside engineering drawings of the test rack and its components.

Test rack replica

Before completion of the Divider test, preparations had already begun for the next test, Icecap, including construction of its test rack and tower. However, just days after Divider, a nuclear testing moratorium went into effect and Icecap was canceled. The 152-foot rack and tower are still in place at the NNSS today, and a miniature replica of the Icecap tower was included in the anniversary display.

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The Divider test rack during setup at the Nevada Test Site (now the Nevada National Security Site). 


Several key maps were on display, including one that shows the locations of the nuclear tests—including Divider—conducted at the NNSS. At approximately 1,355 square miles, the test site is larger than Rhode Island.