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FISSIONABLE Charles P. Blair Last revised: 2012

“While several isotopes are theoretically fissionable, RANNSAD defines fissionable isotopes as either -233 or 235; 238, 239, 240, 241, or 242, or -241. See, Ackerman, Asal, Bale, Blair and Rethemeyer, Anatomizing Radiological and Nuclear Non-State Adversaries: Identifying the Adversary, p. 99-101, footnote #10,

TABLE 2.III.1. FISSIONABLE ISOTOPES1

Isotope Availability Possible Fission Bare Critical -types mass2 Uranium-233 MEDIUM: DOE reportedly stores Gun-type or implosion-type 15 kg more than one metric of U- 233.3 Uranium-235 HIGH: As of 2007, 1700 metric Gun-type or implosion-type 50 kg of HEU existed globally, in both civilian and military stocks.4 Plutonium- HIGH: A separated global stock of Implosion 10 kg 238 plutonium, both civilian and military, of over 500 tons.5 Implosion 10 kg Plutonium- Produced in military and civilian 239 reactor . Typically, reactor Plutonium- grade plutonium (RGP) consists Implosion 40 kg 240 of roughly 60 percent plutonium- Plutonium- 239, 25 percent plutonium-240, Implosion 10-13 kg nine percent plutonium-241, five 241 percent plutonium-242 and one Plutonium- percent plutonium-2386 (these Implosion 89 -100 kg 242 percentages are influenced by how long the is irradiated in the reactor).7

1 This table is drawn, in part, from Charles P. Blair, “Jihadists and Nuclear ,” in Gary A. Ackerman and Jeremy Tamsett, ed., Jihadists and Weapons of Destruction: A Growing Threat (New York: Taylor and Francis, 2009), pp. 196-197. See also, David Albright N 2 “Bare ” refers to the absence of an initiator or a reflector. 3 “Global Report 2006,” International Panel on Fissile Materials, p. 15. Available at: http://www.fissilematerials.org/ipfm/site_down/ipfmreport06.pdf. See also, John Holdren and Matthew Bunn, “Types of Nuclear Bombs, and the Difficulty of Making Them,” Nuclear Threat Initiative, 2002. Available at: http://www.nti.org/e_research/cnwm/overview/technical2.asp#_ftn4. 4 “Global Fissile Material Report 2007,” International Panel on Fissile Materials, , Table 1B.1, p. 21. Available at: http://www.fissilematerials.org/ipfm/site_down/gfmr07.pdf. See also, Global Stocks of Nuclear Materials, Summary Tables and Charts, Institute for and International Security (ISIS), 2004. Available at: http://www.isis-online.org/global_stocks/end2003/tableofcontents.html. 5 David Albright and Kimberly Kramer, Plutonium Watch, Tracking Plutonium Inventories, Institute for Science and International Security, August 2005, pp. 1-11. Available at: http://www.isis- online.org/global_stocks/end2003/plutonium_watch2005.pdf. 6 See , Plutonium: A History of the World’s Most Dangerous Element, (, DC: Joseph Henry Press, 2007), pp. 159-160. 7 Richard L. Garwin and , Megawatts and Megatons: The Future of Nuclear and Nuclear Weapons, (Chicago: The Press, 2001), pp. 136-137. See also, See, J.

TABLE 2.III.1. FISSIONABLE ISOTOPES1

Isotope Availability Possible Fission Bare Critical Weapon-types mass2 - VERY LOW: Produced in isotope Gun-type or implosion-type 162 kg 2318 production reactors. Very small quantities exist for research. - VERY LOW: Very small amounts Implosion 7 kg 236 found in scientific research (it has no commercial use).9 Neptunium- HIGH: An estimated 54 tons Gun-type or implosion-type 59-60 kg 237 globally. Small amounts found in commercial and scientific applications. Large quantities found in spent .10 Americium- HIGH: Total for all americium Implosion-type 57 kg-100 kg 241 (241, 242m, 243) estimated to be 87 tons.11 Small amounts found in commercial and scientific applications. Larger quantities found in .12 Americium- LOW: Small amounts found in Implosion-type 9-18 kg 242 commercial and scientific applications. Large quantities found in spent nuclear fuel.13 Americium- LOW: Small amounts found in Implosion-type 50-155 kg 243 commercial and scientific applications. Larger quantities found in spent nuclear fuel.14 -24315 VERY LOW: Available in Gun-type or implosion-type 7-10 kg milligram quantities only. Found in spent reactor fuels. Curium-244 VERY LOW: Available in Implosion-type 30 kg milligram quantities only. Found in spent reactor fuels. Curium-245 VERY LOW: Available in Implosion-type (possibly a 10-13 kg milligram quantities only. Found in gun-type candidate) spent reactor fuels. Curium-246 VERY LOW: Available in Implosion-type 39-84 kg milligram quantities only. Found in

Carson Mark, “Reactor-Grade Plutonium’s Explosive Properties,” NPT/95, Nuclear Control Institute, August 1990. Available at: http://www.nci.org/NEW/NT/rgpu-mark-90.pdf. 8 Protactinium has 20 known isotopic, scientists note, yet “only protactinium-231 has a half- greater than one and is a concern for Department of (DOE) environmental management sites.” See “Protactinium,” Human Health Fact Sheet, Argonne National Laboratory, August 2005. Available at: http://www.ead.anl.gov/pub/doc/protactinium.pdf 9 Albright and Barbour, “Troubles Tomorrow? Separated Neptunium 237 and Americium.” 10 Ibid. 11 “Global Stocks of Nuclear Explosive Materials, Summary Tables and Charts.” 12 Albright and Barbour, “Troubles Tomorrow? Separated Neptunium 237 and Americium.” 13 Ibid. 14 Ibid. 15 For Curium, see, “Curium,” Argonne National Laboratory, Human Health Fact Sheet, August 2005. Available at: http://www.ead.anl.gov/pub/doc/curium.pdf. Page 2 of 3

TABLE 2.III.1. FISSIONABLE ISOTOPES1

Isotope Availability Possible Fission Bare Critical Weapon-types mass2 spent reactor fuels. Curium-247 VERY LOW: Available in Implosion-type (possibly a 7 kg milligram quantities only. Found in gun-type candidate) spent reactor fuels. - Has not yet been fabricated in an Implosion-type (possibly a 10 kg 247 elemental form. gun-type candidate) - VERY LOW: Very small bulk Implosion-type 6 kg 249 quantities found in spent reactor fuels. Californium- VERY LOW: Very small bulk Implosion-type (possibly a 9 kg 251 quantities found in spent reactor gun-type candidate) fuels.

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