much smaller than the more common electricity-producing reactors — the reactor vessel measures across and high, with the core a mere tall and across, and it does not generate electricity. As a special feature, it allows scientists to simultaneously test materials in multiple unique experimental environments. Research scientists can place experiments in one of the more than 70 test positions in the reactor. Each can generate unique experimental conditions. Some have called the reactor a "virtual time machine", for its ability to demonstrate the effects of several years of radiation on materials in a fraction of the time. The ATR allows scientists to place a variety of materials in an environment with specified intensities of radiation, temperature, and pressure. Specimens are then removed to examine how the time in the reactor affected the materials. The U.S. Navy is the facility's primary user, but the ATR also produces medical isotopes that can help treat cancer patients and industrial isotopes that can be used for radiography to x-ray welds on items such as skyscrapers, bridges and ship holds. Many ATR experiments focus on materials that could make the next generation of nuclear reactors even safer and longer lasting. Materials and Fuels Complex (MFC) Hot Fuel Examination Facility The Hot Fuel Examination Facility (HFEF) gives INL researchers and other scientists the ability to examine and test highly radioactive irradiated reactor fuel and other materials. HFEF provides 15 state-of-the-art workstations known as hot cells. For windows, each cell has leaded glass panes layered thick and separated by thin layers of oil. Remote manipulators allow users to maneuver items inside the hot cell using robotic arms. Special filtered exhaust systems keep indoor and outdoor air safe. At these stations, scientists and technicians can better determine the performance of irradiated fuels and materials. Scientists can also characterize materials destined for long-term storage at the Waste Isolation Pilot Plant in New Mexico. Space and Security Power Systems Facility The New Horizons mission to Pluto, which launched in 2006, is powered by a device fueled at the INL Space and Security Power Systems Facility. The Radioisotope Thermoelectric Generator (RTG) uses nonfissionable nonweapons-grade plutonium to produce heat and electricity for deep space missions such as this one. Using the RTG on the New Horizons mission is a more practical power source for the satellite than solar panels because the satellite will travel to such a great distance that energy