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Prototype build of a card model of the X-12A nuclear locomotive concept
After half-a-century experience with the commercial use of nuclear power, it may seem difficult to conceive the sustainability of a nuclear-powered train engine.
In 1954, however, Professor Lyle B. Borst and his colleagues at the University of Utah pursued a concept for a locomotive powered by a nuclear reactor. Babcock & Wilcox Co. co-designed the reactor in a private venture. The project was dubbed X-12 and attracted the interest of five railroad companies, nine manufacturers, and the international media [1,2]. The locomotive was projected to cost 1.2 million dollars in 1954, double the price of four contemporary diesel units coupled together to produce the same horse powers.
Operating on only 14 kg liquid fuel, the locomotive was envisaged to span 58 meters in length and muster 7,000 horse powers, rivaling the remarkably strong Ae 8/8 electric locomotives of the Swiss BLS Railway of the same epoch. These double units with Bo'Bo'+Bo'Bo' wheelbase (UIC classification) were only half that long.
Though, the X-12 would theoretically reach 60 miles/h in breath-taking 3 minutes and 32 seconds, pulling a 5,000-ton train, the nuclear locomotive would have weighed 360 tons. The reactor's radiation shielding mustered 200 tons alone. By contrast, the whole afore-mentioned electric Ae 8/8 weighs roughly as much as the shielding of the X-12 (180 metric tons).
The X-12's stream-lined body emulated the diesel locomotive design of the 1950s [1,2]. The two-sectioned behemoth was to consist of a 38-meter long engine, with a cab up front and the power plant behind, plus a 20-meter long 'tender' carrying the radiators for cooling turbine steam. The assembly was conceived to rest on an articulated platform riding on a (Co'Co')(Co'Co')(4) wheelbase (UIC classification).
The power plant was to consist of the nuclear reactor, the main steam turbine for power generation as well as steam condensers and chillers. A gear box coupled the turbine shaft to four electric generators.
The unavoidable massive radiation shielding called for small components in the engine room. At a rotor shaft length of only 120 inches and a diameter of only 24 inches, the team accomplished to design powerful space-saving generators that, despite their small size, could cope with the demands of the twelve 600-horsepower electric motors driving 24 wheels.
Further accommodating the limited space available, the engine's reactor was to possess a peculiar design. The reactor core was to be filled with liquid uranium oxide dissolved in sulphuric acid, providing greater symmetry for neutron fluxes at smaller neutron loss than the other popular, less efficient designs that used solid fuel packed into rods [3].
The fuel core of the X-12's reactor was supposed to measure only 36 inches in diameter and 10 inches deep. The reactor pressure vessel, clad in an eight-inch steel primary shield, was made to fit into the 13 x 13 x 9 feet cavity of a secondary fluid-tight shield, also made of eight inch steel, encompassing the middle section of the engine and measuring 15 by 15 by 10 feet on the outside. The space between the two shields was to be filled with high viscosity hydrocarbon fluid to absorb internal motion on accidental impact and a hydrogenous shielding material to absorb more radiation.
The reactor consisted of a cylindrical reactor pressure vessel, shorter than wide, in which a steam-driven pump force-circulates the core's fluid, representing the primary coolant circulation for nuclear fission heat transfer. For secondary cooling, roughly 10,000 ¼-inch stainless steel tubes, traversing the core, join an inlet and an outlet chamber attached to each end of the reactor pressure vessel. The water-filled chambers, covering a large part of the reactor core surface, were thought to double as coolers and neutron reflectors, diminishing the escape of neutrons from the core. Coolant pumped through the tube and chamber system feeds steam to the main turbine. An additional coolant loop circulates through the chiller banks in the tender, cooling the turbine's exhaust steam in the main condenser.
However, if built, it would have had a high capital cost, and the requirement of weapons grade uranium and all those radioactive components ensured that the X-12 was never built.
Prototype build of a card model of the X-12A nuclear locomotive concept
After half-a-century experience with the commercial use of nuclear power, it may seem difficult to conceive the sustainability of a nuclear-powered train engine.
In 1954, however, Professor Lyle B. Borst and his colleagues at the University of Utah pursued a concept for a locomotive powered by a nuclear reactor. Babcock & Wilcox Co. co-designed the reactor in a private venture. The project was dubbed X-12 and attracted the interest of five railroad companies, nine manufacturers, and the international media [1,2]. The locomotive was projected to cost 1.2 million dollars in 1954, double the price of four contemporary diesel units coupled together to produce the same horse powers.
Operating on only 14 kg liquid fuel, the locomotive was envisaged to span 58 meters in length and muster 7,000 horse powers, rivaling the remarkably strong Ae 8/8 electric locomotives of the Swiss BLS Railway of the same epoch. These double units with Bo'Bo'+Bo'Bo' wheelbase (UIC classification) were only half that long.
Though, the X-12 would theoretically reach 60 miles/h in breath-taking 3 minutes and 32 seconds, pulling a 5,000-ton train, the nuclear locomotive would have weighed 360 tons. The reactor's radiation shielding mustered 200 tons alone. By contrast, the whole afore-mentioned electric Ae 8/8 weighs roughly as much as the shielding of the X-12 (180 metric tons).
The X-12's stream-lined body emulated the diesel locomotive design of the 1950s [1,2]. The two-sectioned behemoth was to consist of a 38-meter long engine, with a cab up front and the power plant behind, plus a 20-meter long 'tender' carrying the radiators for cooling turbine steam. The assembly was conceived to rest on an articulated platform riding on a (Co'Co')(Co'Co')(4) wheelbase (UIC classification).
The power plant was to consist of the nuclear reactor, the main steam turbine for power generation as well as steam condensers and chillers. A gear box coupled the turbine shaft to four electric generators.
The unavoidable massive radiation shielding called for small components in the engine room. At a rotor shaft length of only 120 inches and a diameter of only 24 inches, the team accomplished to design powerful space-saving generators that, despite their small size, could cope with the demands of the twelve 600-horsepower electric motors driving 24 wheels.
Further accommodating the limited space available, the engine's reactor was to possess a peculiar design. The reactor core was to be filled with liquid uranium oxide dissolved in sulphuric acid, providing greater symmetry for neutron fluxes at smaller neutron loss than the other popular, less efficient designs that used solid fuel packed into rods [3].
The fuel core of the X-12's reactor was supposed to measure only 36 inches in diameter and 10 inches deep. The reactor pressure vessel, clad in an eight-inch steel primary shield, was made to fit into the 13 x 13 x 9 feet cavity of a secondary fluid-tight shield, also made of eight inch steel, encompassing the middle section of the engine and measuring 15 by 15 by 10 feet on the outside. The space between the two shields was to be filled with high viscosity hydrocarbon fluid to absorb internal motion on accidental impact and a hydrogenous shielding material to absorb more radiation.
The reactor consisted of a cylindrical reactor pressure vessel, shorter than wide, in which a steam-driven pump force-circulates the core's fluid, representing the primary coolant circulation for nuclear fission heat transfer. For secondary cooling, roughly 10,000 ¼-inch stainless steel tubes, traversing the core, join an inlet and an outlet chamber attached to each end of the reactor pressure vessel. The water-filled chambers, covering a large part of the reactor core surface, were thought to double as coolers and neutron reflectors, diminishing the escape of neutrons from the core. Coolant pumped through the tube and chamber system feeds steam to the main turbine. An additional coolant loop circulates through the chiller banks in the tender, cooling the turbine's exhaust steam in the main condenser.
However, if built, it would have had a high capital cost, and the requirement of weapons grade uranium and all those radioactive components ensured that the X-12 was never built.