Greenhouse Item was an American nuclear test conducted on May 25, 1951, as part of Operation Greenhouse at the Pacific Proving Ground, specifically on the island of Engebi in the Eniwetok Atoll in the Central Pacific Ocean. This test explosion was the first test of a boosted fission weapon. In this test deuterium-tritium (D-T) gas was injected into the enriched uranium core of a nuclear fission bomb. The extreme heat of the fissioning bomb produced thermonuclear fusion reactions within the D-T gas, but not enough of them to be considered a full nuclear fusion bomb. This fusion reaction released a large number of free neutrons, which greatly increased the efficiency of the nuclear fission reaction. The explosive yield of this bomb was 45.5 kilotons, about twice the yield of the unboosted bo