The 100-Ton Test
On 7 May 1945, soldiers and technicians stacked 100 tons of TNT on a 20-foot platform for a calibration and procedures check. The known explosive quantity provided a benchmark for seismographs, blast gauges, and other instruments. A small amount of radioactive material was threaded through the stack in tubing to calibrate other instruments.
Although it was understood that the atomic bomb’s yield could be as high as 20,000 tons, test plans were based on yield limited to 10,000 tons with the most probable yield estimated as 4,000 tons, if it worked at all. Much was learned and refined for what was to be the first field, rather than laboratory, atomic test.
Although the 100-ton test was spectacular, as the flash was seen 60 miles away, it was soon overshadowed by Trinity’s yield of 21 kilotons.