#thermonuclear testing

 Our predecessors really were out there sending Cesium-137 out into the atmosphere to an extent that it can be reliably used as a benchmark for dating sedimentation.

Excellent writeup by Alex Wellerstein on Andrei Sakharov and the Soviet Union's first thermonuclear test– RDS-37.

The blast created a crater 6,240 feet (1.9 km) in diameter and 164 feet (50 m) deep where Elugelab had once been; the blast and water waves from the explosion (some waves up to twenty feet high) stripped the test islands clean of vegetation, as observed by a helicopter survey within 60 minutes after the test, by which time the mushroom cloud and steam were blown away. Radioactive coral debris fell upon ships positioned 35 miles (48 km) from the blast, and the immediate area around the atoll was heavily contaminated for some time. Produced by intensely concentrated neutron flux about the detonation site were two new elements, einsteinium and fermium.

Operation Greenhouse was the first sort-of thermonuclear weapon testing done. The majority of its yield came from standard fission, however there was a small amount of Deuterium and Tritium at its center. It had a small blast but led the way for Ivy Mike the next year.