b'A P P E N D I X BReactorLast Day of Name Acronym S t a r t u p OperationMaterials Test Reactor (continued)addition, its beam holes made it possible to perform cross-section and other physics research.The high-flux radiation fields available in this reactor made it possible to accelerate the screening of potential reactor materials. In its early years, the MTR contributed to the design of pressurized water, organic-moderated, liquid-metal-cooled, and other reactors. Successful operation of the MTR itself was a great experiment resulting in a family of plate-type reactors. The reactor operated at a power level of 30 megawatts until September 1955 when thermal output was increased to 40 megawatts. The MTR logged more than 125,000 operating hours and more than 19,000 neutron irradiations. During August 1958, the MTR became the first reactor to operate using plutonium-239 as fuel at power levels up to 30 megawatts. The demonstration showed that a plutonium-fueled reactor could be controlled satisfactorily.The materials testing workload of the MTR was taken over by the new and larger Advanced Test Reactor.31. Mobile Low-Power Reactor No. 1 ML-1 3-30-61 5-29-64Following the operation of the GCRE, the ML-1 was the next major step toward the development of a mobile low-power power plant for the U.S. Army. The entire ML-1 plant was designed to be transported either by standard cargo transport planes or standard Army low-bed trailers in separate packages weighing less than 40 tons each.The reactor was operated remotely at the ARA-IVarea from a control cab at a distance of approximately 500 feet. It could be moved after a 36-hour shutdown. The reactor was designed for ease of operation and maintenance by enlisted technicians at remote installations, for reliable and continuous operation under extreme climatic conditions, and for the rigors of shipment and handling under adverse conditions.The ML-1 shut down for the last time after operating for a total of 664 hours. Before the ML-1 had reached all of its performance goals, the Army phased out its reactor development program around 1965.32. Natural Circulation Reactor S5G 9-12-65 5-1-95The S5G (submarine reactor, 5th prototype, General Electric) was the prototype of a pressurized-water reactor for USS Narwhal. Located at the Naval Reactors Facility, it was capable of operating in either a forced or natural circulation flow mode. In the natural mode, cooling water flowed through the reactor by thermal circulation, not by pumps. Use of natural circulation reduced the noise level in the submarine.To prove that the design concept would work in an operating ship at sea, the prototype was built in a submarine hull section capable of simulating the rolling motion of a ship at sea. The S5G continued to operateas part of the Navys nuclear training program until that program was reduced after the end of the Cold War.33. Neutron Radiography Facility NRAD ContinuingThe NRAD, located in the Hot Fuel Examination Facility at Argonne-West, is a nondestructive examination tool. Using two collimated neutron beams produced by a 250-kilowatt reactor, NRAD produces neutron radiographs showing the internal condition of highly irradiated test specimens without physically cutting into the specimen. The reactor also has been used as a neutron source for isotope production, activation analysis, and the evaluation of radiation effects on materials.34. Nuclear Effects Reactor FRAN 8-28-68 June 1970The Nuclear Effects Reactor (FRAN) was a small-pulsed reactor, capable of supplying bursts of high-intensity fast neutrons and gamma radiation. FRAN was transferred to the NRTS in mid-1967 from the Nevada Test Site, where it had been operated by Lawrence Livermore National Laboratory.Located in the ARAbuilding formerly occupied by the ML-1 reactor, FRAN was used for a short time to test the performance of new detection instruments then being developed for reactor control purposes. The reactor was moved back to DOEs Lawrence Livermore National Laboratory in June 1970.265'