Drive of the Month: Semipalatinsk Test Site

Chagan was a Soviet underground nuclear test conducted at the Semipalatinsk Test Site on January 15, 1965. It left a huge lake-filled crater.

Radiation levels surveyed at Lake Chagan are among the highest in the Safecast radiation database.

A Safecast volunteer, who’d like to be identified simply as “Markus,” recently uploaded data from the Semipalatinsk Test Site and nearby areas in Kazakhstan.

He used a bGeigie Nano to survey radiation levels near Lake Chagan, also known as Lake Balapan, site of a Soviet underground nuclear test conducted on January 15, 1965. This shallow subsurface test was one of over 100 Soviet nuclear detonations intended to prove that nuclear weapons could be used to perform major earthmoving tasks, such as making lakes and harbors. It was similar to the US Sedan test done at Yucca Flat in Nevada in July, 1962, as part of Operation Plowshare, and appears to have been modeled on it closely. The Sedan test left a crater about 390 meters (1,280 ft) in diameter and 100 meters (330 ft) deep. Lake Chagan is similar in size, about 408 meters (1,338 ft) in diameter and 100 meters (328 ft) deep.

The  bGeigie Nano on the shore of Lake Chagan

As at the sites of US aboveground tests done in the desert, the Chagan detonation melted exposed rock and sand into a glassy substance known as “trinitite.” As Markus’ data shows, the Chagan site is still highly radioactive. In fact, outside of Fukushima and Chernobyl, the radiation levels at Chagan the highest surveyed so far by Safecast volunteers.

Reaching the site requires a long drive across the steppe.

Other volunteers have measured nuclear bomb test sites in Bikini Atoll and Enewetak. Sites like these are relatively inaccessible, and we appreciate that the people who did these surveys brought a bGeigie along on their difficult trips.

An IAEA radiological assessment report from 1998 gives a lot of basic information about conditions at the Semipalatinsk site. This map shows the Chagan/Lake Balapan site (which we’ve highlighted in red) in relation to other test zones.


Markus also surveyed other locations in Kazakhstan, such as the city of Almaty.