megawatts. The design fuel temperature was , with a temperature rise across the core, though the peak temperature reached in steady operation and peaked at in transients. of fuel flowed through the reactor per minute at a core pressure of about . Sodium was pumped through the reactor at a rate of per minute with about of pressure. The fuel salt transferred heat to a helium loop, which then transferred the heat to water. Additionally, the reflector and moderator blocks were cooled with a liquid sodium metal cooling loop, which also transferred heat to helium and then water. The reactor contained one neutron source (15 curies of polonium-beryllium), one regulating rod, and three helium-cooled boron carbide shim rods. The experiment was instrumented with two fission chambers, two compensated ionization chambers, and 800 thermocouples. The ARE control system could automatically scram the reactor based on high neutron flux, fast reactor period, high reactor exit fuel temperature, low heat exchanger fuel temperature, low fuel flow rate, and loss of offsite power. Development program The heat exchanger chamber took up significantly more space than the reactor and dump tank chambers. The ambitious goals and military importance of the ANP catalyzed a significant amount of research and development of complex systems in challenging high-temperature, high-radiation environments. Corrosion and hot sodium handing studies began in 1950. Investigations of the engineering and fabrication problems involved in handling molten fluoride salts began in 1951 and continued through 1954. Natural-convection corrosion test loops were operated to down-select suitable material and fuel combinations. Subsequent studies in forced-circulation test loops established means to minimize corrosion and mass transfer. Development of pumps, heat exchangers, valves, pressure instrumentation, and cold traps spanned from late 1951 to summer 1954. Much of the work was based on extensive experience at lower temperature from Argonne National Laboratory and the Knolls Atomic Power Laboratory. Techniques had to be developed concerning the construction, preheating, instrumentation, and insulation of reliable leak-tight high-temperature circuits made of Inconel. They found that all-welded construction was necessary. In all, equipment development in support of high-temperature leak-tight operation lasted about four years. The ARE Hazards Summary Report was issued on November 24, 1952. A low-temperature critical mockup of the reactor was assembled to verify the calculation models. The BeO moderator blocks were fitted with straight tubes filled with a powder mixture to simulate the fuel. Critical mass, regulating rod worth, safety rod worth,