The beginning of the 20th century can truly be called the time of electricity. In a relatively short period, it penetrated absolutely all aspects of human activity, and by the end of the 30s it was already impossible to imagine humanity without it. And having such an example in front of our eyes, in the second half of the 40s, they expected exactly the same victorious step from atomic energy. The atom had to solve the main problem of electricity - the need to connect to the network or constantly change power supplies.
A nuclear battery in a coffee maker will last for decades, and most likely the device will be thrown away due to a breakdown before the charge runs out. In addition, such a battery will make the coffee maker mobile, it can be used at home, you can take it on a visit or on a trip. But before reaching household appliances, the atom had to show itself in big things - atomic ships, atomic planes, atomic machines and trains. It is about the latter that I would like to talk about. In the Russian segment of the Internet, Soviet projects are a little highlighted, and only a couple of words about American works on this topic. And I would like to fix it.
They started talking about atomic trains almost immediately after the end of the Second World War, so in March 1946 the Mechanix Illustrated magazine published an article "Atomic Engines for Peace", which covered the possibility of using an atomic reactor in trains. It was proposed with the help of heat from the reactor to heat the water that drives steam turbines, which in turn will power the electric generators. The heated water can also be used to heat the cars. According to preliminary calculations, a nuclear engine will be 40% lighter than a conventional internal combustion engine of a diesel locomotive of the same power. In addition, such a nuclear locomotive does not need to be refueled, which means that it can not be changed along the entire route. But so far, ideas remained ideas.
Nuclear locomotive as presented by Mechanix Illustrated.
Nuclear locomotive design in Mechanix Illustrated view.
For the first time, they seriously engaged in the creation of an atomic engine for a locomotive in 1952, moreover, it all started with a student project. In the spring of 52, Professor Lyle Borst, who had time to take part in the Manhattan Project and then taught nuclear technology at the University of Utah, decided to give the senior group of students the most difficult task for their graduation project. After some deliberation, he decided that this would be the creation of a reactor suitable for use in locomotives and a propulsion system for it. According to Borst, this task was quite difficult at that time, and he could not find a single known study on this topic, which means that students could not cheat. The group included graduate students who had already graduated from the institute for help, and the basis was made up of senior students. By the summer of 52, they had checked preliminary studies and presented them to Borst - the result was encouraging, the creation of a small reactor was quite possible. And this attracted the interest of the professor himself, he saw in an atomic locomotive not only a train, but also an opportunity to create sufficiently compact nuclear reactors and thereby support the peaceful development of nuclear energy. From that moment on, Borst personally headed the group of researchers and was closely engaged in the project. From that moment on, Borst personally headed the group of researchers and was closely engaged in the project. From that moment on, Borst personally headed the group of researchers and was closely engaged in the project.
Comparison of the nuclear locomotive X-12 and other variants of locomotives.
The main challenge facing the team was the size of the reactor. If weight was almost not a problem, then to install a nuclear boiler on a locomotive, it was required to strictly observe all dimensions - the height, and most importantly, the width of the reactor. There were other problems as well. Since the initial composition of the group was almost not versed in locomotive building, since 1953 Borst began to actively attract for work, first his acquaintances, railway engineers, and later specialists from such well-known companies as Commonwealth Edison, Westinghouse and Babcock & Wilcox. This became possible after receiving a federal research grant in the fall of 1953. The amount received, although it was small, made it possible to calmly design a nuclear locomotive, although there could be no talk of full-scale tests so far. It was during this period that the project received the name - X-12. The locomotive being created was intended exclusively for freight traffic, since the existing and promising technologies could not yet help in the creation of an atomic passenger train.
Promotional video:
Nuclear locomotive X-12.
By the middle of 1954, the project began to take shape. The X-12 locomotive was supposed to consist of two sections. The first housed a reactor, a turbine, condensers and generators. In addition, the driver's cab was located in the first section, so the reactor was well shielded. All this weighed 720 tons, because the first section was placed on three three-axle bogies. Also, the reactor gave off too much excess heat, and the entire second section was occupied by radiators, utilizing this heat. She had two carts - the first with three axles and the second with two. The total length of the two sections was 49 meters - thus, although the X-12 was not the largest locomotive at that time, it was clearly in the top five. Borst and his group decided not to be smart and used the already worked out scheme of a diesel locomotive in the locomotive, only replacing the diesel engine with a reactor and a turbine. The reactor generates steam, which spins the turbines that power the generators.
The design of the X-12 turbine.
The locomotive housed one turbine that fed four generators, each with a capacity of 1.3 MW. All 9 axles of the first section and three axles of the first bogie of the second section are leading. As a result, the locomotive produced 8,000 horsepower in normal mode and could be boosted to 10,000 horsepower for a short time. Unfortunately, it was not possible to fit a two-circuit heat transfer system in a limited volume, and radioactive water entered the turbine directly from the reactor, contaminating it. Therefore, the turbine was supposed to be made without the possibility of maintenance - every one and a half years, the contaminated turbine would be removed from the locomotive and replaced with a new one. Although this would lead to an increase in operating costs, the benefits of using a nuclear reactor would still cover them.
Internal structure of the X-12.
The heart of the X-12 was to be a water nuclear reactor with a homogeneous core. In this embodiment, the reactor core is a homogeneous mixture of nuclear fuel with a moderator; there were no fuel elements. The choice in favor of such a scheme was due to the fact that this type of reactor at that time was the least secret and simple enough to create. In addition, it was easy to maintain, and in the event of overheating of the reactor and its boiling, due to the low vapor coefficient of reactivity, the reaction was interrupted on its own. Also, this scheme was distinguished by a low consumption of nuclear fuel and the ability to quickly change the output power. The main disadvantage of such a design is that it was proposed to overcome the rapid deterioration of the reactor structure using new materials, including those still in development.
Early design of the X-12 nuclear reactor.
As a result, the size of the reactor was 1 meter high and 1 meter wide and 0.4 meters long. The reactor contained 19.8 kilograms of highly enriched uranium (with an 80% uranium-235 content) dissolved in 357 liters of water. The choice in favor of weapons-grade uranium was made due to the extremely small volume of the reactor. The average temperature of the mixture in operation is 237 degrees Celsius. Constant circulation of the mixture to avoid uranium deposition and to maintain a constant temperature was provided by two pumps in the upper part of the reactor. To control the reaction, there were reflectors and rods made of boron and steel. In normal operation, the reactor produced 30 MW of thermal energy. To transfer this energy through the working area of the reactor, 10,000 pipes with water passed. The water in them turned into steam, which entered the turbine, spinning it up to 6000 rpm. After that, the steam entered the condenser section, where it again turned into water and was sent back to the reactor.
Late design of the X-12 nuclear reactor.
To protect it from radiation, the reactor was surrounded by water and shielded by a steel shield with intervals of wax and gypsum. In addition, it was supposed to use a similar material in the construction of generators, thereby using them also as protection. The reactor was to be controlled by two specially trained engineers located in the utmost proximity to the reactor zone. According to calculations, the maximum period of safe work for them was a year, in shifts in three days. After, in order to avoid the accumulation of harm from radiation, it was proposed to transfer these engineers to other positions. Serious attention was paid to the emergency shutdown of the reactor in the event of a locomotive accident. The design of the locomotive was specially calculated to absorb the shock (a similar design is used in modern cars). Besides,the protective shell was also designed for additional shock absorption. A mechanism was incorporated into the design of the control rods, which releases all the rods with a sharp change in speed, thereby, in the event of an accident, the reactor will be shut down. There was also the most simple and reliable reactor cooling system, which could function even after the impact and prevent the reactor from melting before the arrival of emergency teams.
Locomotive scheme X-12.
In January 1954, Borst launched an advertising campaign for X-12 in the popular science press - during the winter and spring, almost every popular science publication in America and many in the world wrote about the atomic locomotive. The main goal of this company was to find an investor for the further development of the project. According to calculations, to build the first test locomotive, Borst's team needed $ 4 million for research and $ 1.2 million for the construction itself (of course, all prices are at the 1954 rate). In addition, access to the facilities of a large railway plant was needed. Such expenses were offset by the benefit from the absence of the need to constantly refuel the locomotive, the possibility of its continuous use for days, or even weeks. As a result, one locomotive would pay for itself in 10 years of work,and with the construction of 5 locomotives, all costs will be recouped in 12 years. The main benefit was the use of the X-12 on long-distance and ultra-long routes. So Borst's team proposed the use of the X-12 on the Pan American highway that was being designed at that time, passing through the whole of North and South America. The average freight train for the X-12 was estimated at 120 cars weighing up to 20,000 tons at a speed of 80 kilometers per hour.
Illustration of the X-12 locomotive.
A funny feature was that the reactor was launched exclusively at the plant when the locomotive was released from the shops and after that it was almost impossible to access it. It was assumed that a reactor of this type will quietly serve for 3 years, after which the locomotive will again come to the plant, where the reactor will be replaced. As mentioned above, the turbine was replaced every year and a half, but this could also be done at a specially created service station. Every six months, at the same station, 50 liters of a water-uranium mixture were added to the reactor for refueling. At this moment, Borst's team made a mistake or deliberately cheated - since the cost of weapons-grade uranium at that time was secret, Borst indicated it at $ 20 per gram, while in reality at that time, weapons-grade uranium cost up to $ 120 per gram. If a real figure was used, the economy of the X-12 would be seriously reduced. Two versions of a locomotive with a crew of 2 and 4 people were developed. In the first case, there were no engineers overseeing the reactor, and since Borst's team was confident in the reliability of their nuclear boiler, this was the main option.
Locomotive model X-12.
By 1955, Borst presented his group's project at several conferences and exhibitions, but with the high interest of the public, potential customers had many questions. Almost immediately, the military abandoned the project - they admitted that in the future nuclear trains may take their place on the railways, but so far all their requirements have been satisfied by ordinary locomotives. Private firms had much more interest, the greatest interest was shown in Babcock & Wilcox, where in 1955 a commission was assembled to analyze the project. After 2 months of research, the conclusions were disappointing - the Kh-12 was recognized, although promising, but excessively dangerous, in the event of an accident the losses would be so large that they would block all possible benefits.
Many inventors fixate on their brainchild, for years, if not decades, trying to push it into life. Lyle Borst was not like that. Since the project had no prospects in the near future, he decided to close it. The whole team received invaluable work experience and now could calmly move on both in science and in career. Borst himself continued his scientific activities, without a doubt leaving the X-12 behind. He later recalled that perhaps if he had shown great perseverance, perhaps he could have paved the way for the X-12, at least as a prototype. But the chances of this were frankly small and, therefore, Borst never doubted the correctness of the decision to close the nuclear locomotive project. This is where the history of the X-12 ends, but the history of atomic trains is just beginning.