NEEP602 Course Notes (Fall 1996)
Resources from Space
3He Fusion: A Safe, Clean, and Economical Energy Source For Future Generations
Professor G. L. Kulcinski
March 29, 1996
From the previous lecture it is clear that Fusion Energy could provide that new energy source in the middle of the 21st Century that was postulated in Lecture 4. However, in spite of over 10 billion dollars of research, worldwide, in the past 30 years, the DT Tokamak does not appear to be the ultimate answer. The problem lies in both the DT fuel cycle, which emits 80% of its energy in highly damaging and radioisotope producing neutrons, and in the complex design of the Tokamak.
Advantages of Fuel Cycles Based on 3He
The details of the DT, DD, D3He, and 3He3He fuel cycles are given in Figure 2. Note the reaction products and the energy released per reaction.
Because of side or secondary reactions (e. g., the D in the D3He fuel reacting with other D instead of 3He) some fuel cycles have more radioactivity associated with them than others. See Figure 3. Clearly the most attractive fuel cycle, in terms of radioactivity produced are those using the 3He fuel cycle. It is almost certain that the p11B cycle will not work in Maxwellian plasmas (i. e., Tokamaks, Mirrors, ICF, etc.) because of the bremsstrahlung associated with high Z elements in a hot plasma. It may be possible to run 11B in an IEF device. See Lecture 26.
The amount of energy released in neutrons is very much a function of the plasma temperature for the D3He reaction (Figure 4).
A summary of the way in which energy is released from the 4 most attractive fusion reactions is given in Figure 5. The energy release fraction is expressed in terms of neutron, transport (ion leakage), bremsstrahlung (breaking radiation from electrons), and synchrotron (energy lost from hot electrons and ions in high magnetic fields) losses. See the general fusion references cited in Lecture 26 for more information. Conversion of neutron and bremsstrahlung radiation to electricity will be limited by Carnot efficiencies (~30-40%), whereas the direct ion conversion efficiencies could be twice that value (Santarius, 1987, 1990)
There are 5 main technological features that make D3He fusion attractive.
Direct conversion of the kinetic energy of charged particles to electricity has been demonstrated experimentally and can reach 60-80%
The conversion of microwave radiation directly to electricity has also been accomplished experimentally as evidenced by a spectacular experiment in Canada, See Santarius, 1990 for more details.
The overall efficiencies of fission and fusion reactors are given in Figure 8 with fusion systems using direct conversion clearly favored.
An overall summary of the key technological features of fusion power plants is given in Figure 9 and normalized with respect to fission reactors.
Specifically the overall environmental and safety characteristics of D3He power plants are (Kulcinski, et al., 1987, 1991, 1992a, 1992b, 1992c, 1993, Khater, 1993):
and those for 3He3He are:
It is possible to rate the 4 fuel cycles with respect to proliferation, radiation damage, nuclear waste, safety, tritium, and physics requirements. This is given in Figure 12.
How long would it take to build research facilities, prototypes, and eventually commercial reactors from the IEF-Polywell concept?
If the use of 3He fuels is so great, why hasn't it been done before?
Remember, when burned with D,
1 kg 3He = 10 MWe-y of electrical energy
The known present reserves of 3He in the World come from
From Figure 15 it can be seen that only ~ 300-500 kg of 3He could be practically available by the year 2000, mostly from the 3He collected by processing thermonuclear weapons.
On the other hand, this amount of 3He is enough to build and operate all the test facilities that would be needed in the next few decades up to and including a ~ 3-500 MWe fusion power plant or an orbiting 200 MWe power plant. The ultimate problem comes in providing the fuel for a 3He fusion economy. In that situation, tonnes (not kg) of 3He are required.
Where Can We Get Enough 3He?
From our previous lectures (particularly # 18) we have seen that tonnage quantities of 3He have been identified on the lunar surface. Estimates not put the 3He resource at ~ 1 million tonnes.
The tremendous power density in 3He is illustrated by noting how much it would take to provide all of the electricity in the U. S. in 1996. If the required 3He were liquefied, it could fit in the cargo bay of the current U. S. Shuttle.
It is also important to note that today, the energy content in 1 tonne of 3He is worth ~3 billion dollars (if oil is ~ 21 $/barrel). Hence one shuttle load of 3He could more than pay for the Apollo program, even in today's dollars.
For the first time in human history, we can now look at the Moon as a major source of future energy. In fact, the Moon contains 10 times more energy in the 3He on its surface than all the economically recoverable fossil fuels on the Earth (Kulcinski, 1992)!
The United States cannot afford to stay out of this race for the energy resources of the Moon. It would not help us to replace our present dependence on the Mideast for oil with a future dependence on, for example, Japan for our 3He.
Finally, since the original paper (Wittenberg, et al., 1986) connecting the Lunar 3He with the Earth's fusion program, programs on this energy source have sprung up all over the world. The Japanese have mounted the most aggressive program in this area. In the past 10 years alone, twice as many papers have been published with respect to 3He as an energy source than all the papers published on the topic in the previous 50 years (White, 1996).
Khater, H. Y., 1993, "Safety Characteristics of D-3He Fusion Reactors", University of Wisconsin WCSAR-TR-AR3-9307-3, p. 337, [Presented at the Second Wisconsin Symposium on Helium-3 and Fusion Power; Proceedings of a Symposium held in Madison, WI, 19-21 July 1993].
Kulcinski, G. L., Sviatoslavsky, I. N., Emmert, G. A., Attaya, H. M., Santarius, J. F., Sawan, M. E., and Musicki, Z., 1987, "The Commercial Potential of D-He3 Fusion Reactors", 12th Symposium on Fusion Engineering, Monterey, CA, IEEE Cat. No. 87CH2507-2, Vol.Ê1, p. 772.
Kulcinski, G. L., Emmert, G. A., Blanchard, J. P., El-Guebaly, L. A., Khater, H. A., Maynard, C. W., Mogahed, E. A., Santarius, J. F., Sawan, M. E., Sviatoslavsky, I. N., Wittenberg, L. J., 1991, "Apollo-L3, An Advanced Fuel Fusion Power Reactor Utilizing Direct and Thermal Energy Conversion," Ninth Topical Meeting on the Technology of Fusion Energy, Oak Brook, IL, Fusion Technology, 19, p. 791.
Kulcinski, G. L., Cameron, E. N., Santarius, J. F., Sviatoslavsky, I. N., Wittenberg, L. J., and Schmitt, H. H., 1992a, "Fusion Energy from the Moon for the 21st Century", Lunar Bases and Space Activities of the 21st Century Second Symposium, April 1988, NASA Conf. Publ. 3166, p. 459.
Kulcinski, G. L., Emmert, G. A., Blanchard, J. P., El-Guebaly, L. A., Khater, H. A., Maynard, C. W., Mogahed, E. A., Santarius, J. F., Sawan, M. E., Sviatoslavsky, I. N., Wittenberg, L. J., 1992b, "Safety and Environmental Characteristics of Recent D-3He and DT Tokamak Power Reactors", Fusion Technology, Vol. 21, No. 3, Part 2B, p. 1779.
Kulcinski, G. L., Emmert, G. A., Blanchard, J. P., El-Guebaly, L. A., Khater, H. A., Maynard, C. W., Mogahed, E. A., Santarius, J. F., Sawan, M. E., Sviatoslavsky, I. N., Wittenberg, L. J., 1992c, "Summary of Apollo, A D-3He Tokamak Reactor Design", Fusion Technology, 21, No. 4, p. 2292.
Kulcinski, G. L., 1993, "History of Research on 3He Fusion", University of Wisconsin WCSAR-TR-AR3-9307-3, p. 9, [Presented at the Second Wisconsin Symposium on Helium-3 and Fusion Power; Proceedings of a Symposium held in Madison, WI, 19-21 July 1993].
Santarius, J. F., 1987, "Very High Efficiency Fusion Reactor Concept", Nuclear Fusion, 27, p. 167.
Santarius, J. F., Blanchard, J. P., Emmert, G. A., Sviatoslavsky, I. N., L. J. Wittenberg, et al., and the ARIES Team, 1990, "Energy Conversion Options for ARIES-III--A Conceptual D/He-3 Tokamak Reactor", Proc. of 13th Symposium on Fusion Engineering, Knoxville, TN, IEEE Cat. No. 89CH2820-9, p. 1039.
White, S. W., 1996, "A Current Bibliography of Helium-3 Research", University of Wisconsin Report UWFDM-1003, January 1996.
Wittenberg, L. J. Santarius, J. F. and Kulcinski, G. L.,1986, "Lunar Source of He-3 for Commercial Fusion Power", Fusion Technology, 10, p.167.
1.) Explain how a DT fusion reactor might be considered a proliferation threat and why would a D3He reactor not be considered as such a threat?
2.) How much tritium would one have to have to provide the 3He fuel for an annual U. S. Electrical Demand of 500 GWe?
3.) What is the total thermal energy associated with 1,000,000 metric tonnes of 3He burned with D? What is the equivalent amount of barrels of oil?
4.) If you had an electrical power plant that could be located in the center of a population area, what kinds of savings would you reap on your electrical bill? (i. e., what cost areas in a present coal or fission plant could you reduce or eliminate?)
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