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Radioisotope Sources

Grant Meadows 2015 Fall Modern November 2015 Grant Meadows, November 2015, November Meadows, Grant Modern Physics Fall 2015 Outline

• Describe the fundamentals of nuclear sources, including the radioisotope power source (RPS) • Review radioactivity, the fundamental phenomena of radioisotope power sources • Explain interactions of with • Finally, conclude with the energy transfer mechanisms of RPS’s Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant Fundamentals of Nuclear Energy Sources • RPS uses from decay of radioactive elements to generate • Difference between , , and RPS’s: • Nuclear fusion uses the energy released from fusing (combining) elements, like , into heavier elements, like • Although the is powered by nuclear fusion, no device on earth has ever released more energy than consumed. Hence, they cannot be

used to generate electricity yet 2015 Fall Physics Modern • Nuclear fission uses energy released by fissioning (breaking apart) or to create heat for generating electricity 2015, November Meadows, Grant • All commercial nuclear reactors use fission • Fission reactors produce radioactive elements, but only part of their reaction process Nuclear Fusion, Fission Modern Physics Fall 2015 Fall Physics Modern Fig 1: Nuclear fusion reactor. Fig 2: Nuclear fission reactor. Reactor Pulse

The Reactor. at Texas A&M Nuclear Center. 2015, November Meadows, Grant Digital image. Digital image. Texas A&M University CEA , Nuclear Science Center, n.d. Web. 22 Nov. 2015. 03 Dec. 2013. Web. 22 Nov. 2015. Characteristics of RPS

• The radioisotope power source is practical, unlike fusion, yet cannot be turned on and off, unlike fission • Great application as a long-lasting, dependable, high supply of electricity • Can in extreme environments and isolated locations Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant Historical Use

• Characteristics have historically created appeal for pacemakers and NASA space missions • Examples of NASA space missions include all Apollo missions, Viking 1 and 2, Voyager 1 and 2, Mars pathfinder, and New Horizons Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant

Fig 4: New Horizons Spacecraft RPS. Fig 3: Nuclear-Powered Cardiac Pacemaker. PHOTO NO: KSC-05PD-2411. Digital image. The Off-Site Source Recovery Project. Digital image. John F. Kennedy Space Center. Los Alamos National Laboratory, n.d. Web. 22 Nov. 2015. NASA, 04 Nov. 2005. Web. 22 Nov. 2015. What is Radioactivity?

• Stable and radioactive elements throughout • Two charts are useful to understand radioactivity: Chart of Stability, and Curve Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant Chart of Stability and Binding Energy Curve Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant

Fig 5: Chart of Stability Bazin, Daniel. Nuclear Landscape. Fig 6: Binding Energy Curve. Digital image. Digital image. .com. Scienceblogs.com. Nature Publishing Group, 20 June 2012. Pearson Prentice Hall and Web. 22 Nov. 2015. University of Wisconsin Stevens Point, 2005. Web. 22 Nov. 2015. Interactions of Radiation With Matter • Alpha Particles- ionized Helium-4 particles interact through Coulomb Scattering • Coulomb Scattering involves transferring of He- 4 particles to , which gradually slows them down • Particles- or electrons interact through Coulomb Scattering with other electrons • Also interact through radiation, which are x-

rays emitted because of electrons decelerating 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant Interactions of Radiation With Matter • Gamma Rays- Interact through: • Photoelectric Absorption • Photon is absorbed by , releases • Compton Scattering • Photon scatters free electron, losing kinetic energy to it • Pair Production • Photon disintegrates into an electron- pair, which annihilates soon after creation, leaving as two equal 2015 Fall Physics Modern energy photons Grant Meadows, November 2015, November Meadows, Grant Source Considerations

• Lifetime of sources is proportional to half-life • For shielding purposes, gamma rays are difficult to shield, so beta and alpha emitting are primarily used • Popular fuel sources: • Plutonium 238 • Strontium 90 Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant Fig 7: Plutonium 238 Plutonium Pellet. Digital image. Department of Energy, 1997. Web. 22 Nov. 2015. Types of Radioisotope Power Sources • Radioisotope Thermoelectric Generator: • Uses Seebeck Effect to generate current from hot and cold ends of two different elements. Heat comes from decay of particles Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant Fig 8: Seebeck Effect. Thermoelectrics. Digital image. Department of Physics. Fig 9: Multi-Mission University of Oslo, 28 Nov. Radioisotope Thermoelectric 2012. Web. 23 Nov. 2015. Generator. Digital image. NASA, n.d. Web. 23 Nov. 2015. Types of Radioisotope Power Sources • Stirling Cycle Radioisotope Generator: • Uses heat output to drive a mechanical device under the Stirling Cycle, which moves a magnet to generate electricity Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant

Fig 10: Stirling Radioisotope Generator. ASRG Labeled Cutaway. Digital image. Wikipedia. Wikimedia Commons, 26 Feb. 2012. Web. 23 Nov. 2015. Conclusion

• Radioisotope power sources are different from nuclear fusion and nuclear fission • RPS’s use the laws of radioactivity to generate electricity through creative ways of harnessing heat production • Are great for long-lasting, high energy density, steady-power applications Modern Physics Fall 2015 Fall Physics Modern Grant Meadows, November 2015, November Meadows, Grant Sources

• Anderson, David, Wayne Wong, and Karen Tuttle. "An Overview and Status of NASA's Radioisotope Power Conversion Technology NRA." 3rd International Energy Conversion Engineering Conference (2005): n. pag. Web. • "Radioisotope Power Systems." NASA and Department of Energy, n.d. Web. 23 Nov. 2015. • Schmidt, George R., Robert L. Wiley, Rebecca L. Richardson, and Richard R. Furlong. "NASA's Program for Radioisotope Power System Research and Development." AIP Conference Proceedings (2005): n. pag. Scitation.aip.org. Web. 23 Nov. 2015. • Anderson, David J. "An Overview and Status of NASA's Radioisotope Power Conversion Technology NRA." Space Technology and Applications International Forum (2005): n. pag. Stanford University. NASA Glenn Research Center, Nov. 2005. Web. 23 Nov. 2015. • Krane, Kenneth S., and David Halliday. Introductory . New York: Wiley, 1988. Print. • "Nuclear-Powered Cardiac Pacemakers." Facts about Pacemakers. Los Alamos National Laboratory, n.d. Web. 23 Nov. 2015. 2015 Fall Physics Modern • United Nations. International Agency. Vienna, Austria. Industrial Uses of Large

Radiation Sources. Vol. II. Salzburg: Conference Proceedings, 1963. International Atomic Energy 2015, November Meadows, Grant Agency. Web. 23 Nov. 2015. • "Thermoelectrics." Department of Physics. University of Oslo, 28 Nov. 2012. Web. 23 Nov. 2015. • Lange, Robert G., and Wade P. Carroll. "Review of Recent Advances of Radioisotope Power Systems." Energy Conversion and Management 49.3 (2008): 393-401. Web.