The Open-pool Australian lightwater reactor (OPAL) is a 20 megawatt (MW) swimming pool nuclear research reactor. Officially opened in April 2007, it replaced the High Flux Australian Reactor as Australia's only nuclear reactor, and is located at the Australian Nuclear Science and Technology Organisation (ANSTO) Research Establishment in Lucas Heights, New South Wales, a suburb of Sydney. Both OPAL and its predecessor have been commonly known simply as the Lucas Heights reactor. Functions The main reactor uses are: Irradiation of target materials to produce radioisotopes for medical and industrial applications Research in the fields of materials science and structural biology using neutron beams and its sophisticated suite of experimental equipment Analysis of minerals and samples using the neutron activation technique and the delay neutron activation technique Irradiation of silicon ingots in order to dope them with phosphorus and produce the basic material used in the manufacturing of semiconductor devices The reactor runs on an operation cycle of 30 days non-stop at full power, followed by a stop of 5 days to reshuffle the fuel. During year 2014 OPAL ran a total of 290 days at power, and over 300 days in 2015. History The Argentine company INVAP was fully responsible through a turnkey contract, signed in June 2000, for the delivery of the reactor, performing the design, construction and commissioning. Local civil construction was performed by INVAP's partner, John Holland-Evans Deakin Industries. The facility features a large () liquid-deuterium cold neutron source, modern supermirror guides, and a guide hall. The cold source was designed by the Petersburg Nuclear Physics Institute, the cryogenic system designed and supplied by Air Liquide and the initial set of four supermirror guides supplied by Mirrotron. On 17 December 2001, 46 Greenpeace activists occupied the Lucas Heights facility to protest the construction of OPAL. Protestors gained access to the grounds, the HIFAR reactor, the high-level radioactive waste store and the radio tower. Their protest highlighted the security and environmental risks of the production of nuclear materials and the shipment of radioactive waste from the facility. OPAL was opened on 20 April 2007 by then Australian Prime Minister John Howard and is the replacement for the HIFAR reactor. ANSTO received an operating licence from the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) in July 2006, allowing commencement of hot commissioning, where fuel is first loaded into the reactor core. OPAL went critical for the first time