By: Vincent Iacono
The United States started its nuclear aircraft program in 1946 with a program called the NEPA. The NEPA stood for the Nuclear Energy for Propulsion of Aircraft. It was started by the Royal Air Force in 1946, and by 1948, ten million dollars had been spent in the program (Everything.com 2003 and Wikipedia 2008). The NEPA’s goal was to do research on the feasibility of nuclear aeronautics, and most of this research was done at the Oak Ridge National Laboratory (Schulin 2003). It was ended in 1951, when it joined with another group to create the ANP (Wikipedia 2008).
The other group that joined the NEPA was started in 1948 and was called the Atomic Energy Commission and was created by students at the Massachusetts Institute of Technology (MIT) to test the feasibility of nuclear aeronautics, when the two joined together, they created another group called the ANP (Everything.com 2003). This group from MIT came up with a final report called the Lexington report which stated that nuclear powered flight was possible, but would take over fifteen years to develop and would cost over one billion dollars (Schulin 2003).
The ANP stands for Aircraft Nuclear Propulsion program. While the NEPA’s goal was to do research in the nuclear field, the ANP’s goal was much more ambitious, and they wanted to develop a proto-type (Everything.com 2003). In order to create this proto-type, the ANP had to find information on reactor materials for shielding, and had to create designs for reactors in three to five years (Schulin 2003). Funding issues slowed down these programs, but most of these goals were still achieved.
The ANP studied two types of Nuclear Powered jet engines. Two companies were charged with the task of building two different engines (Everything.com 2003). Pratt and Whitney’s Aircraft Company was the first corporation to be contracted by the NEPA, and started their work in 1953. This engine used an indirect cycle system, which used nuclear fission to melt metal, the liquid metal heats air which turns a turbine (Schulin 2003). By the end of the ANP, Pratt and Whitney never made a working indirect-cycle system reactor.
The second reactor was made by General Electric, it was a direct-air cycle systems, and was very successful (Wikipedia 2008). The reactor works by heating air directly with nuclear fission, and the heated air turns a turbine. The first working nuclear jet engine was a General Electric modified J-47 Turbojet (Schulin 2003). It was created in 1956, and the reactor was called the Heat Transfer Reactor Experiment No.1 (HTRE-1), several others were developed later. It eventually operated for more than 120 hours including 65 hours. The HTRE-1 was later followed by the HTRE-2, and the HTRE-3 could power two turbojet engines (Schulin 2003).
Although the focus of the report is mainly on the American Air Forces, the Russian Air Force did create several nuclear dependant aircraft, one of them being the Tupolev TU-95 LAL. The Soviet nuclear program was experimental and it was estimated that it would take twenty years to complete a working model, and it started on August 12, 1955. Much like the B-36, a small reactor was put into a working Tupolev bomber, and the Soviets conducted 34 research flights to see radiation levels. Although the experiment looked promising, it was shut down because of advances in other fields which led nuclear aeronautics to become useless for the Russians (Wikipedia 2008).
President Kennedy shut the ANP down on March 28, 1961. The shielding of the reactor for radioactive purposes was never completely finished due to the fact that the shielding weighed too much for the plane to carry (Schulin 2003). The ANP had spent over one billion dollars of 1957 value. Schulin (2003) further states that the building materials of the plane and reactor could not handle the intense heat created by the fission process, and it was not powerful enough at the time to completely protect the crew members from radiation. The Lockheed study was created to find the design differences that would need to be calculated within nuclear bombers compared to other ones. The first recalculation needed would be the landing weight of the plane, and the effect it would have on the landing gears because a normal plane loses about half of its weight to fuel consumption, but a nuclear plane would land with the same weight that it took off with, which meant that better landing gears would be needed (Schulin 2003). The second issue of radioactivity led to the concept of divided shielding, which would focus the shielding on the cockpit and the reactor, the only problem with this was that radiation was free to go anywhere within the aircraft, and some could get lost in the environment. Thirdly, the reactors would weigh huge amounts, and while the aircraft would be able to hold it, the focus of weight in one area would take a lot of structural consideration into the design of the craft Schulin 2006).
In the late 1940s, the ideas of nuclear fission and the development of aerospace propulsion systems were bigger then ever, and when the government decided to merge the two together, it was the dawn of a new nuclear aeronautical age (Schulin 2003). The driving force behind these nuclear powered aircrafts was the silent war in the US and Soviet Russia (Wikipedia 2008). These new planes had the potential to keep nuclear weapons in the sky for months at a time, which would dissuade the other country from attacking (Everything.com 2003 and Wikipedia 2008). The US and Russia conducted long experiments, but over time both countries cancelled their programs, and no models were ever actually made in production numbers (Schulin 2003, everything.com 2003 and Wikipedia 2008).
Oak Ridge National Laboratory
The United States’ goal was to build a supersonic manned bomber, but due to technical and financial problems, they decided to convert an existing Convair B-36 bomber. A small reactor was installed in the bomb bay, and the plane was re-named the X-6. The bomber was used for shield development and radiation tests, and is known as the Nuclear Test Aircraft (NTA). The NTA was fitted with a one megawatt reactor in order to simulate radiation. According to Everything.com (2003), the nose section of the bomber was rebuilt with twelve tons of lead and rubber, shielding was added around the reactor, and water jackets were placed around the fuselage of the aircraft (to absorb radiation) all as little things to help take away radiation from the crew members. The aircraft completed 47 flights from 1955-57, and stopped being tested when the ANP shut down (Schulin 2003 and Everything.com 2003).