support and resource center for planning, real-time assessment, emergency response, and detailed studies of incidents involving a wide variety of hazards, including nuclear, radiological, chemical, biological, and natural atmospheric emissions. National Ignition Facility: This 192-beam, stadium-size laser system is used to compress fusion targets to conditions required for thermonuclear burn. Experiments at NIF study physical processes at conditions that exist only in the interior of stars and in exploding nuclear weapons (see National Ignition Facility and photon science). Superblock: This unique high-security facility houses modern equipment for research and engineering testing of nuclear materials and is the place where plutonium expertise is developed, nurtured, and applied. Research on highly enriched uranium also is performed here. Livermore Computing Complex: LLNL's Livermore Computing Complex houses some of the world's most powerful computers, including the 20 petaflop Sequoia, the 5-petaflop Vulcan system; Jade and Quartz systems at 3 petaflops each; the 970-teraflop Zin system; 431-teraflop Cab system; and additional large multi-core, multi-socket Linux clusters with various processor types. The newest machine, Sierra, occupied the No. 3 position on the TOP500 list in June 2018. The complex has nearly 10,000 square feet of machine floor space, supporting both classified and unclassified national security programs. Titan Laser: Titan is a combined nanosecond-long pulse and ultrashort-pulse (subpicosecond) laser, with hundreds of joules of energy in each beam. This petawatt-class laser is used for a range of high-energy density physics experiments, including the science of fast ignition for inertial confinement fusion energy. Largest computers Throughout its history, LLNL has been a leader in computers and scientific computing. Even before the Livermore Lab opened its doors, E.O. Lawrence and Edward Teller recognized the importance of computing and the potential of computational simulation. Their purchase of one of the first UNIVAC computers set the precedent for LLNL's history of acquiring and exploiting the fastest and most capable supercomputers in the world. A succession of increasingly powerful and fast computers have been used at the Lab over the years. LLNL researchers use supercomputers to answer questions about subjects such as materials science simulations, global warming, and reactions to natural disasters. LLNL has a long history of developing computing software and systems. Initially, there was no commercially available software, and computer manufacturers considered it the customer's responsibility to develop their own. Users of the early computers had to write not only the codes to solve their technical problems, but also the