TX-5 bomb was used to create the conditions needed to initiate the fusion reaction. This "primary" fission stage was nested inside the radiation case at the upper section of the device, and was not in physical contact with the "secondary" fusion stage. The TX-5 did not require refrigeration. Running down the center of the Dewar flask within the secondary was a cylindrical rod of plutonium within a chamber of tritium gas. This "fission sparkplug" was imploded by x-rays from the primary detonation. That provided a source of outward-moving pressure inside the deuterium and increased conditions for the fusion reaction. Surrounding the assembly was a natural uranium "tamper". The exterior of the tamper was lined with sheets of lead and polyethylene, forming a radiation channel to conduct X-rays from the "primary" to the "secondary" stage. As laid out in the Teller-Ulam design, the function of the X-rays was to compress the "secondary" with tamper/pusher ablation, foam plasma pressure and radiation pressure. This process increases the density and temperature of the deuterium to the level needed to sustain a thermonuclear reaction, and compress the "sparkplug" to a supercritical mass – inducing the "sparkplug" to undergo nuclear fission and to thereby start a fusion reaction in the surrounding deuterium fuel. The entire "Mike" device (including cryogenic equipment) weighed . It was housed in a large corrugated-aluminum building, called the shot cab, which was long, wide, and high, with a signal tower. Television and radio signals were used to communicate with a control room on the USS Estes where the firing party was located. It was set up on the Pacific island of Elugelab, part of the Enewetak atoll. Elugelab was connected to the islands of Dridrilbwij (Teiteir), Bokaidrikdrik (Bogairikk), and Boken (Bogon) by a artificial causeway. Atop the causeway was an aluminum-sheathed plywood tube filled with helium ballonets, referred to as a Krause-Ogle box. This allowed gamma and neutron radiation to pass uninhibited to instruments in an unmanned detection station, Station 202, on Boken Island. From there signals were sent to recording equipment at Station 200, also housed in a bunker on Boken Island. Personnel returned to Boken Island after the test to recover the recording equipment. In total, 9,350 military and 2,300 civilian personnel were involved in the "Mike" shot. The operation involved the cooperation of the United States army, navy, air force and intelligence services. The USS Curtiss brought components from