February 20, 2003
Quantum Nucleonics May Power USAF UAVs

Picture Global Hawk Unmanned Aerial Vehicles (UAVs) that can fly continuously for months.

The AFRL now has other ideas, though. Instead of a conventional fission reactor, it is focusing on a type of power generator called a quantum nucleonic reactor. This obtains energy by using X-rays to encourage particles in the nuclei of radioactive hafnium-178 to jump down several energy levels, liberating energy in the form of gamma rays. A nuclear UAV would generate thrust by using the energy of these gamma rays to produce a jet of heated air.

A tutorial on quantum nucleonics provides some details on the science involved.

A friend who knows a fair amount of physics thinks that pumping the hafnium nuclei up to a high energy state to make them into a suitable fuel source would be a fairly inefficient process because most of the x-ray energy would not hit the nuclei to cause the needed energy jump. Many times more energy would be needed to pump the nuclei up into a higher energy state than would be given back as the jump down to a lower state and release their energy. Therefore quantum nucleonics is not an approach suitable for large scale energy storage use.

The advantage over batteries or even hydrogen fuel is that quantum nucleonics can be used to produce a material with a much higher energy density. In specialty applications such as military UAVs the energy costs may be worth it because the high energy density would allow continuous operation of a UAV for a long period of time.

The technology seems like it would be more attractive for UAV use over oceans than over land. A UAV that crashed over an ocean would likely sink to the bottom taking its radioactive material with it far beyond the reach of humans. There are plenty of naval military applications for UAVs such tracking enemy fleets, surveilling ships to look for possible terrorist ships carrying WMD, as well as search and rescue. There are also civilian scientific applications such as continuous data collection on weather and environmental monitoring. Plus, search and rescue is a civilian need as well. One can even imagine long duration UAVs being used as lower altitude equivalents of communications satellites.

Update: Back in August 2001 some Lawrence Livermore National Laboratory scientists published a result that argues against the possibility of using hafnium-178 as an energy storage material.

LIVERMORE, Calif.—Physicists from the Lawrence Livermore National Laboratory, in collaboration with scientists at Los Alamos and Argonne national laboratories, have new results that strongly contradict recent reports claiming an accelerated emission of gamma rays from the nuclear isomer 31-yr. hafnium-178, and the opportunity for a controlled release of energy. The triggering source in the original experiment was a dental X-ray machine.

Using the Advanced Photon Source at Argonne, which has more than 100,000 times higher X-ray intensity than the dental X-ray machine used in the original experiment, and a sample of isomeric Hf-178 fabricated at Los Alamos, the team of physicists expected to see an enormous signal indicating a controlled release of energy stored in the long lived nuclear excited state. However, the scientists observed no such signal and established an upper limit consistent with nuclear science and orders of magnitude below previous reports.

Share |      Randall Parker, 2003 February 20 11:34 AM  Airplanes and Spacecraft


Comments
menon said at October 17, 2004 8:29 AM:

Fittting such engines on aircraft:

1. How safe it is during a possible crash?

2. In the event of a crash and a possible radiation leak, what will be the extent of the damage due to radiation

3. Health risks for personnel working on the aircraft.

4. It is said that Hf 178 cannot be used on WMD. But use of the same as a radiation threat cannot be ruled out IF any such aircraft is shot down or stolen.

James Schubert said at November 6, 2005 6:17 AM:

Charging a quantum nuclear laser (the power source for the UAV) is inneficient for a small sample because most of the x-rays go through without being absorbed, but this is not true if you charge a large sample which is so thick that all of the x-rays are absorbed.
Most quantum nuclear research does not involve charging ground state nuclei because naturally charged nuclei are readily available. Any time a radioactive element undergoes an alpha decay (a helium nucleus breaks off of the larger radioactive nucleus), the resulting nucleus is not in the most compact possible state (it is not in its ground state). Such "out of round" nuclei will naturally undergo a nuclear rearrangement resulting in a more compact, sherical nucleus. This rearrangement of the nucleus results in the release of a gamma ray. These are the gamma rays which can be released in a controlled manner by the gamma ray laser to power the UAV.

James Schubert said at November 6, 2005 6:53 AM:

Hafnium and Tantalum are not the only quantum nuclear isomers (nuclei with long-lived, above ground state quantum levels). Every isotope of every element has its own unique nuclear spectra. Most nuclear spectra look like the spectra of a rareified gas (with very specific absorbtion and emission spectra related to specific quantum states). This means that unlike conventional fission fuels, the isotopes do not need to be separated to make a useful fuel (no enrichment process like uranium) because non-target nuclei are transparent to the specific gamma ray colors which are heavily absorbed by the target nuclei.
Some nuclear spectral lines are very close together (corresponding to small rearrangements or chamges in spin of the nucleus). Some lines are so close together that they can be "tickled" by visible photons. Triggering of nuclear emission by visible photons has already been demonstrated, with the release of an ultraviolet photon (which because of its nuclear origin is called an ultraviolet gamma ray).
In the midst of an energy crisis, we have just now discovered that we are swimming in a sea of available energy which we had been completely unaware of. Anyone else who finds it difficult to stop thinking about quantum nucleonics can email James Schubert at Seastealthusa@aol.com

Tony Verhaaf said at December 9, 2007 10:01 AM:

how would this work for a commercial power plant?

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