(YB-60) Nuclear powered aircraft

On April 27, 1949, a conference was held at Oak Ridge National Laboratory, Tennessee (ORNL), between NEPA contractors, the Air Force, and AEC personnel, with the intent to plan Oak Ridge participation in the NEPA project. The ORNL NEPA effort was called the Aircraft Nuclear Propulsion project (ANP) and was established under Air Materiel Command project officer Lt Col Clyde D. Gasser.

See: NEPA History 1

ANP was a more vigorous program than the original NEPA project, and really began to seriously tackle the many problems posed by nuclear flight. Fairchild was dropped as the prime contractor and major design efforts began at Lockheed and Convair's Fort Worth division. While many types of engines were studied by ANP, including giant propellers driven by steam turbines, as of 1951-2 the Air Force's vision of an operational nuclear-powered bomber centered on the mammoth Convair YB-60, a swept-wing, turbojet-powered modification of the B-36 strategic bomber. It was a far cry from Newsweek's compact 1945 flying wing. NEPA's July 1947 report had set its sights on the goal of building an aircraft in the 300,000 lb gross weight range, with a speed of 515 mph at 35,000 ft and a weapon load of 12,000 lb. The B-60 closely followed those criteria.



YB-60 prototype, Spring 1952


The nuclear powerplant designed for the B-60 was the General Electric P-1, an air-cycle reactor with a thermal output probably in the 50 megawatt range, which was married to four powerful GE XJ53 turbojet engines by a complex tangle of air ducts. The reactor would be cooled both by the airflow from the turbojets and by boron-laced shielding water circulating through its shell. As the XJ53 had a rated thrust of about 17,500 lb, the four nuclear-heated engines would have had approximately the same thrust as all eight conventional J57s on the rival Boeing XB-52.

Air from the turbojet compressors would flow directly through the reactor core, where it would be heated to some 2,000 degrees F before being returned to the engine turbine sections. Though this was a relatively simple and direct method of constructing the nuclear engine, it had the drawback of producing an exhaust plume that would contain radioactive particles and contaminants.


A prototype GE X39 nuclear-heated turbojet, based on the J47 used in the B-47 bomber, shows air duct scrolls for connection to the reactor (arrows). With a thrust output of between 5,000 and 7,000 lb, this engine was used for ground testing of reactor prototypes.







When the P-1 engine was applied to the actual B-60 production nuclear-powered bomber, the reactor/J53 engine complex apparently would have been installed in the aft bomb bay area of the fuselage, as far as possible from the crew compartment. The arrows, below, indicate the probable location of the engine assembly. (The B-60 flew numerous times powered by conventional turbojets, but never with the nuclear engines). Heavy shielding was planned, consisting of tanks of a water-boron solution (boron-10 isotope is an excellent neutron absorber), plastics (possibly polyethylene with boron or lead additives) and layers of metal such as lead, steel and tungsten. The crew compartment itself would have had additional shielding. This "divided shielding" concept was considered one of the major technical breakthroughs of the early NEPA project.





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Nuclear Aircraft Powerplant Experiments

The map below shows the Idaho National Engineering and Environmental Laboratory (INEEL), where NEPA powerplant experiments were conducted in the 1950s.





INEEL (established in 1949 as the National Reactor Testing Station) Test Area North (above) was the site of Heat Transfer Reactor Experiments -- "HTRE" -- aircraft nuclear engine prototype ground-based testing, which began in 1955. The nuclear-powered aircraft prototype would have been flown from here. A huge hangar was constructed (black building, center right), but not the fifteen thousand foot runway that a ponderous nuclear plane would have required. A multi-mile runway for the X-6 reportedly was also considered at Edwards Air Force Base, California, running between Muroc dry lake and Rosamond dry lake, but it too was never built.

The hangar and associated maintenance facilities were built with enormously thick, nuclear-shielded walls and bays. General Electric, the program contractor, planned to equip the engine maintenance facilities with closed-circuit television systems and remote manipulator arms to allow technicians to work on the aircraft and its powerplant without direct exposure to the intense radiation field that would persist even after the reactor was shut down. Since the turbojets essentially functioned as the cooling system for the reactor, they would have to be run at high power settings even after shutdown of the reactor in order to maintain cooling airflow through the still-hot core. After an initial cooldown period, ground cooling systems would be connected to the reactor and the engines could be shut down as the P-1 was extracted from the airplane and placed in its shielded storage bay.

The initial HTRE engine experiments were intended to prove out the engineering and operational concepts for a nuclear bomber powerplant, but without the restrictions on weight and size that an airplane powerplant would demand. These early assemblies were gigantic monstrosities weighing at least a hundred thousand pounds, and were built on railcars which would move them to remote test locations far from their assembly, maintenance and control facilities. When the engineering aspects of the designs were proven, the next step would be to reduce the size of the designs while increasing their power output, with the goal of producing a final, operational version of the design that would be "flightweight" and "flightsize" with a thermal output of at least 50 megawatts. This was to be done in stages over a several year period.





HTRE-3



HTRE-1, also known as the Core Test Facility, the initial aircraft engine/reactor testbed, was mounted on a huge mobile railroad car assembly. It was a water-moderated uranium reactor with a beryllium reflector and shielding that included large quantities of mercury. The two jet engines just visible at lower left would be started using hot gas produced by chemical-fuel combustors. Once the jets were running at speed, the reactor would be brought up to power and airflow would be established through the core. Its heat would then be gradually diverted to the jet turbines as the gas combustor flow was phased out. The jets would be run on nuclear-heated air for periods of hours at a time to simulate the operation of a long-duration nuclear aircraft powerplant. Post-shutdown, the reactor's railcar would be returned to a maintenance bay for disassembly and analysis. HTRE-1 reached power levels as high as 20.2 megawatts. It was later modified to become HTRE-2 and was used for testing special reactor core configurations and materials, reaching power levels of around 14 megawatts.



General Electric began HTRE-1 test runs in 1955 and the reactor successfully powered the X39 engines the following year, although the massive contraption was far from a practical aircraft powerplant. However, HTRE-3 was a major step toward a flight-capable nuclear engine, which would have been designated "XNJ140E-1." According to a program history,

the dimensions of the core and its structural characteristics as well as the design temperatures were those of a power plant capable of providing useful flight propulsion. The power generated by HTRE No. 3 ranged up to 35 megawatts...In the HTRE No. 3 tests, the power levels were so chosen that the fuel element temperatures, the key parameter, would be characteristic of flight service.


General Electric began HTRE-1 test runs in 1955 and the reactor successfully powered the X39 engines the following year, although the massive contraption was far from a practical aircraft powerplant. However, HTRE-3 was a major step toward a flight-capable nuclear engine, which would have been designated "XNJ140E-1." According to a program history.



HTRE-3, without its test structure, closely resembled the original GE P-1 reactor/engine complex concept. Its horizontal layout and lightweight solid hydrided zirconium moderator, as well as its flightweight core and aluminum structural components, were intended to simulate an operational flight reactor. Its size and configuration appear to have been designed with the B-36 or B-60 in mind.

HTRE-3 was operated at the National Reactor Testing Station from April 1958 through December 1960.

It appears that, having solved the aircraft reactor shielding problem and successfully operated a 35 megawatt, flightweight nuclear turbojet powerplant that probably could have propelled an aircraft (at least well enough to impress congressional program critics), the Aircraft Nuclear Propulsion project came rather close to fulfilling the original NEPA design goals of the late 1940s --and in spite of numerous program delays, redirections and even cancellations, it succeded in doing so well within the 15-year period envisioned by the 1948 MIT Lexington Project feasibility study. Nevertheless, the ANP program was cancelled by the new Kennedy administration on March 28, 1961.

If HTRE-3 had existed in 1952, an operational model undoubtedly would have flown in an aircraft, but by 1961 the very existence of manned bombers was threatened by the cheaper, faster and relatively invulnerable ICBM. The large nuclear airplane engine had lost its raison d'etre in the Kennedy/McNamara era

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Nuclear Flight Testing



To serve as an airborne reactor testbed, Convair rebuilt a B-36 in 1955 as a special model called the NB-36H Crusader. The aircraft was equipped with massive shielding and air-cooling ducting (arrows) to support a small nuclear reactor in the aft fuselage. The NB-36H was essentially similar to the earlier X-6 concept, but its reactor was far less powerful and was not capable of propelling the aircraft.



A heavily-shielded, multi-ton sealed crew capsule, equipped with a bank-vault-like hatch and six inch thick windows, was installed in the forward fuselage.



ASTR

The reactor used in these tests was known as ASTR - the Aircraft Shield Test Reactor. It was cooled by circulation of its water moderator through heat exchangers, and produced a nominal 1 megawatt output. ASTR was installed in the NB-36H aft bomb bay in the approximate location of the full-scale P-1 reactor in order to simulate the radiation field and operational techniques of the larger propulsion reactor.

The NB-36 was based at the Convair plant at Carswell AFB, Ft Worth, Texas. On reactor test missions, the aircraft would fly west to the White Sands, New Mexico area where the ASTR would be brought up to power and experiments would begin.

In all, 47 flights were made with the reactor aboard and operating between September 1955 and March 1957. All flights were escorted by an instrumented B-50 bomber and a transport aircraft carrying a crew of specially-trained Marines. In event of a crash of the NB-36 the troops were to parachute to the ground, cordon off the area, and work with local emergency officials to cope with a radiological disaster.

Between the extensive flight testing conducted with the NB-36 and the successful ground testing of the HTRE-3 engine, by the end of 1960 the US had established a considerable fund of engineering know-how and practical experience with aircraft nuclear powerplants. The next step would have been flight testing of the complete engine.

Colonel C. D. Gasser



Col Clyde D. Gasser was Air Materiel Command's liaison officer at Oak Ridge, where the Aircraft Nuclear Propulsion (ANP) division of the Nuclear Energy for the Propulsion of Aircraft (NEPA) program was based.

NEPA was established in the Spring of 1946 as a basic research project to establish the feasibility of powering a plane by nuclear reactions. The NEPA division at Oak Ridge was largely concerned with development and testing of materials that could withstand the intense radiation flux of an operating airborne reactor (which, for weight reasons, was expected to have a minimum of radiation shielding).

See: NEPA: Nuclear Energy for the Propulsion of Aircraft

Gasser evidently consulted with the authors of the Project SIGN report, circa late summer 1948, on the possibility that UFOs were nuclear-powered vehicles. Shortly after the appearance of the Green Fireballs, his speculation that the saucers observed so far might be Soviet aircraft started a small fiasco involving famous radio personality Walter Winchell and FBI director J Edgar Hoover.

The Gasser letter below is reproduced from the DOE archives. It discusses the development of the ANP project at Oak Ridge, which was just being planned when the colonel discussed his UFO opinions with FBI sources.

nuclear power is really clean when its being used, but it is dangerous and when it is no longer usuable it becomes a problem to dispose of

f16falcon.


Yeh.

There is a big debate going on in south australia at the moment about a future nuclear waste site.


They want to make the site near woomera, but the state gov and the people of south australia don't want it.

A modified Kiwi nuclear reactor was deliberately destroyed at the Nuclear Rocket Development Station in Jackass Flats, Nevada, as a safety experiment simulating an accident during a launch. Nuclear scientists imposed a sudden increase in power on the generator, there was a rapid release of heat and energy that caused the reactor to burst apart. The safety experiment was designed to obtain basic reactor shutdown information for use in predicting the behavior of nuclear rocket reactors under a wide range of accident conditions. Kiwi was a project under the National Nuclear Rocket development program, sponsored jointly by the Atomic Energy Commission and NASA as part of project Rover/NERVA (Nuclear Engine for Rocket Vehicle Application). The main objective of Rover/NERVA was to design a flight rated thermodynamic nuclear rocket engine. Kiwi was a prototype for a nuclear rocket reactor that could be used in space travel. Gaseous hydrogen was used as a propellant on the Kiwi-A tests that began in 1959. Kiwi-A served as a learning tool to test specifications and to discover changes that needed to be implemented in the next phase of study, the Kiwi-B series. This project began in December 1961 and used liquid hydrogen as a propellant. In the late 1960's and early 1970's, the Nixon Administration cut NASA and NERVA funding dramatically. The cutbacks were made in response to a lack of public interest in human spaceflight, the end of the space race after the Apollo Moon landing, and the growing use of low-cost unmanned, robotic space probes. Eventually NERVA lost its funding, and the project ended in 1973.

a fascinating topic and this is one possibility that -somehow -always seemed to me to be eminently more feasible than most aircraft speculation.
Kennedy, of course, killed the US programme off in 1961; but I'm sure it's never been entirely abandoned.
A dry and somewhat academic but VERY detailed and factual overview is here:
www.islandone.org...

Nuclear aircraft, nuclear rocket....Do you know what will happen if there is a problem with a nuclear powered reactor ? Look Challenger & Columbia ! Or a nuclear powered aircraft who has a " problem " over a big town, like NYC, London, Brussels....BOOM !

----CNN Breakingnews----

A nuclear powered Boeing 747 crashed in L.A, 500.000 deads !

Terrorists has hijacked a nuclear powered Airbus and crashed it on Big Ben,London. 200.000 deads !

I think that science finds a way of going ahead regardless of the body count or the risk to the world.


we new the risk of the atom bomb and we went ahead with it.

we new the bigger risk of the hydrogen bomb and we still went ahead with it.




I think from memory (orion) and other projects were stopped because of the sighning of the test ban treaty
by kennedy.

actually this is gonna work out, but anyway this is a good plan







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Rapid Prototype

People often argue the danger of nuclear powered aircraft as being dangerous in case of a crash or mistake, however surely the roles which they would have taken on would have involved carrying free fall or standoff nuclear weapons. So what is inherrently more dangerous of a YB-60 or modern version crashing as opposed to a fully nuked up B-52 or B-1

Jensy

Originally posted by jensy
People often argue the danger of nuclear powered aircraft as being dangerous in case of a crash or mistake, however surely the roles which they would have taken on would have involved carrying free fall or standoff nuclear weapons. So what is inherrently more dangerous of a YB-60 or modern version crashing as opposed to a fully nuked up B-52 or B-1

Jensy

Nuclear weapons are actually significantly less radioactive than an active nuclear reactor - a B-52 loaded with nuclear weapons crashing is bad enough (there have already been several examples of such an incident), but a nuclear powered aircraft would be several orders of magnitude worse to clean up.