The Vanowen building was demolished in 2007. In 1959, Atomics International established their headquarters at a complex of buildings located along De Soto Avenue in Canoga Park, California. The De Soto facility hosted the operation of a ten watt L-77 aqueous homogeneous reactor, nuclear reactor fuel fabrication, a gamma irradiation facility, and a radiochemistry laboratory. All of the operations involving radioactive materials were removed by the mid-1990s. The property is now owned and operated by Aerojet Rocketdyne. Space was leased from Thompson-Ramo-Wooldridge Inc, renamed TRW in 1965, for nuclear research projects. It was located at Fallbrook Avenue and Roscoe Boulevard in Canoga Park (present day West Hills). From 1953 to 1989, three primary types of operations were conducted in the Ventura County Simi Hills at Santa Susana Field Laboratory (SSFL) Area IV: Development and testing of nuclear reactors, nuclear support operations, and non-nuclear energy research and development at the Energy Technology Engineering Center. The research operations conducted by Atomics International are known to have caused some degree of chemical and radiological contamination to Area IV. The U.S. Department of Energy has accepted responsibility for the cleanup of both chemical and radiological impacts within Area IV under the 2010 Administrative Order on Consent (AOC). The AOC requires the DOE to clean up both chemical and radiological contaminants to background concentrations within the underlying soils of the 290-acre Area IV. In May 2009, the US Environmental Protection Agency began a $41.5 million survey to determine the nature and extent of any radiological contamination within Area IV. The Advanced Epithermal Thorium Reactor was built for the Southwest Atomic Power Association at Building 100 in 1960. The AETR was used to test twenty different reactor core configurations by using an apparatus which supported a range of geometries. The AETR program was terminated in 1972. Atomics International designed and built a range of low-power (5 to 50,000 watts thermal) nuclear reactors for research, training and isotope production purposes. This aqueous homogeneous reactor type of low-power nuclear reactor used a 93% enriched uranyl sulphate solution held in a critical configuration in a spherical vessel. Reactivity was controlled using an arrangement of control rods within tubes penetrating the reactor vessel. The solution did not boil; rather, neutron and gamma flux caused radiolytic decomposition of water into hydrogen and oxygen in the form of tiny bubbles that gave the impression of boiling.