Some crazy things happened during the Cold War. Dogs were put into orbit, bears were fired out of supersonic jets, and humans landed on the moon. Needless to say, humans were going through a rough break-up and were trying to find themselves. All of these events were centered around one technology that changed the game for every human on this planet, nuclear energy.
The bombing of Nagasaki and Hiroshima woke the world to a nuclear future. Changing the political and cultural landscape of the world forever. Infecting the imaginations of people all over the world. Spawning monster stories like Godzilla, in Japan, and heroes like the Incredible Hulk and Spiderman in the United States. People dreamed of a future where electricity was free, while simultaneously fearing the ever-present threat of nuclear annihilation.
These fears and dreams came together to form perhaps one of the most interesting technologies conceived during the Cold War. Nuclear powered Planes. During World War 2 research and development of nuclear energy had been focused on its weaponization, but with the conclusion of the war, the United States began to seek out ways of utilizing the power of the atom to fuel their energy needs. The Atomic Energy Commission was created in 1946 with the express purpose of commercializing this new technology, and just one year later the US Air Force invested 10 million dollars into studying the feasibility of utilizing this energy to power their long-range bombers. In an era before in-flight refueling and ICBMs had been perfected, the technology was appealing. With just a small amount of fuel, a bomber could fly indefinitely. It would be capable of reaching anywhere in enemy territory.
An omnipotent threat to any advisory. Despite the obvious dangers of combining these two technologies, the possibilities proved too tantalizing. From 1948 to 1951 the brunt of the research centered around a means to transfer the energy generated by nuclear fission to propulsion. Heat energy is gained through nuclear fission. When uranium is bombarded with a neutron it absorbs that neutron into its nucleus, which causes severe vibrations ripping the atom apart, producing heat, additional neutrons, and new lighter atoms. But the sum of products of that split is lighter than the original atom. Experimental proof of Einstein's groundbreaking 1905 paper teaching the world of the energy and mass relationship through the equation of E=mc2. The energy released by a single uranium fission reaction like this is tiny, at 200 million electron volts, but crucially uranium produces additional neutrons when it splits allowing for a chain reaction to occur. So, for very little input energy we can get a tremendous amount of kinetic energy as an output in the form of heat. When controlled this reaction can give us the energy to heat water and power our steam turbines when uncontrolled this reaction gives us the atomic bomb. Experiments began here in the Idaho National Engineering and Environment Laboratory. Dubbed the HTRE, standing for Heat Transfer Reactor Experiment, these engines sought to find the most efficient solution for transforming this
thermal energy into thrust.
They eventually came to the HTRE-3. Consisting of 2 modified general electric J47 engines, that would perform both propulsion and cooling functions. Air would be ducted from the low-pressure compressor through the reactor core, where it would gain heat and expand, this air would then pass through the high-pressure turbine and exhaust to provide power and thrust. As the air was needed for cooling, the engine had to be started using traditional fuel sources, allowing the air to pass through the cool reactor. Once sufficient airflow was achieved the reactor could then be brought up to power. The engine contained a temperature control thermocouple, which fed data to a control module that would automatically close the chemical fuel valve as the heat of the nuclear reactor began to be added until the valve was completely closed.
The HTRE-3 was successfully run multiple times, but there were still several problems to be solved. Perhaps chief among these was the energy transfer method’s propensity for spewing radioactive air out of its exhaust. This was an open or direct cycle configuration, meaning the air is directly used to cool the reactor core. [6] This was a simpler set-up, requiring no additional pumps within the nuclear reactor, that the program managers at General Electric preferred, but resulted in the air passing through the highly radioactive core and thus being contaminated, and subsequently exhausted to atmosphere.
Obviously not an ideal situation, and this program actually spurred the creation of the very first molten salt nuclear reactor through the ARE, or Aircraft Reactor Experiment. This was instead a closed cycle system, where a molten uranium tetrafluoride salt is used as a fuel, while a secondary closed loop containing molten salt with no uranium was used as a coolant. This coolant would then pass through a liquid-to-air heat exchanger to power the turbine. This would result in radically reduced radioactivity in the exhaust, but required more plumbing to circulate the liquids in the two inner closed loops, and resulted in a lower efficiency as we are introducing an additional heat transfer step that allows more heat to be lost to the plumbing and Environment. This method was never tested with a jet engine, but this is the earliest ancestor of the thorium reactors which are easily the most requested topic on this channel, as a result of their potential to provide cheap and safe nuclear energy, but research and funding for this technology were gradually dropped. Had the program developed further, these molten salt reactors likely would have gone on to power any eventually bomber, had the power to weight issues been overcome. This power to weight issues was one of the primary roadblocks facing designers. While nuclear energy can provide extremely long-lasting energy, its power output, the energy provided per unit of time, is not infinite. Nuclear reactors like this have maximum power settings, limited by the heat the cooling system can transport away before it can begin to melt and damage the reactor and its control mechanisms. This made it difficult to design a reactor capable of providing enough energy to power jet engines with enough thrust to get the gargantuan weight of the reactor off the ground.
The HTRE-3 is estimated to have weighed 45 metric tonnes and could produce up to 35 megawatts of thermal output. Far too large and heavy, and short of the 50 megawatts of thermal output targeted for a flight-worthy power source. The HTRE-3 did include removable radiation shielding, consisting of a stainless steel shell with a lead core surrounded by water [R1-4], but further testing was needed to design and assess shielding for an aircraft.
To do this Convair modified a B-36, renaming it the NB-36H Crusader. The B-36 was the only aircraft in the United State’s arsenal capable of taking off with a massive nuclear reactor, and its associated shielding and coolant systems. Fitting it with a small 1-megawatt reactor, dubbed the ASTR, or aircraft shield test reactor, which was lifted from a shielded underground vault and mounted in the B-36s bomb bay moments before take-off.
A plane could never carry the amount of lead needed to shield every facet of a reactor, so this plane would test shadow shielding, which would primarily shield the crew and instruments in the cockpit. Shielding for the reactor was achieved with water tanks which could be filled or drained to vary the shielding and allow the nuclear engineers on board to assess the minimum volume of water needed to protect the plane's crew and instruments, with a 5-tonne 13-centimeter lead shield mounted between the reactor and the crew compartment. On top of this, the crew compartment was an 11-tonne lead and rubber shielded removable section. The leaded glass windows were a foot thick, and a closed-circuit tv system was used to monitor the reactor. The plane was further modified with air scoops to funnel air to the coolant system that would trade heat with the internal closed-loop water coolant, and then exhaust the heat to the atmosphere.
The Crusader made its maiden flight on September 17th, 1955. The reactor provided no power to the engines, but the plane would make a total of 47 flights, which occurred only over remote
land far from human populations. The plane was escorted at all times by a B-50, which contained sensors to measure any air scattered radiation emitted from the reactor and air coolant system. It also contained a team of marines ready to parachute and secure a crash location if the need arose.
At this point, the United States was at the forefront of aircraft nuclear propulsion technology and likely could have developed the technology far enough to produce a nuclear-powered plane. But, for the best, it never came to fruition. On November 18th, 1958 the HTRE-3 engine suffered a meltdown when temperature sensors malfunctioned, recording a lower temperature and withdrawing control rods. This may have been the impetus to shake sense into the US Government, to remind them that a mobile nuclear meltdown was simply not something they wanted to contend with. On top of all this, with the advancement of aerial refueling and intercontinental ballistic missiles, the technology was made completely redundant.
President Kennedy ultimately canceled the program in 1961, just 1 month into his presidency.
Putting an end to the insane idea. This hysteria and fear of aerial bombing has made humans
do some astounding evil and stupid things.
I highly recommend watching the documentary titled the Bombing War: From Guernica to Hiroshima. It takes you from the first small grenade dropped from a plane in World War 1 all the way to the monstrous and unnecessary bombing campaigns that took place in Europe and Asia in World War 2.
0 Comments