NUCLEAR MEDICINE'S DOUBLE HAZARD

Abstract

This article examines the production of metastable technetium-99 (Tc-99m), the world's most important radiopharmaceutical, focusing on reliability of supply and risks of nuclear terrorism. Only four producers manufactured about 95 percent of the world's Tc-99m; a closure of any of them could cause worldwide shortfalls. Moreover, all four employ highly enriched uranium in their production process, in a form relatively easy to convert into the metal needed for a nuclear bomb. The technology to employ low-enriched uranium (LEU)—not usable in weapons—to produce Tc-99m is proven, available, and has been used by smaller producers. However, political determination and sufficient funding are needed to convert the major producers’ isotope production to LEU and encourage new LEU-based production. Such efforts are needed to ensure supplies and reduce security risks.

Keywords:

• Nuclear terrorism
• highly enriched uranium
• low-enriched uranium
• nuclear reactor
• molybdenum-99
• technetium-99m
• medical isotopes

Acknowledgements

The author would like to thank George Vandegrift of Argonne National Laboratory, Ira Goldman and Natesan Ramamoorthy of the International Atomic Energy Agency, Alan Kuperman of the University of Texas at Austin and the Nuclear Control Institute, and Ralph Butler of the University of Missouri Research Reactor for their helpful comments in the preparation of this paper. All opinions and any errors are the responsibility of the author alone.

Notes

1. AECL, operator of the NRU reactor, had reportedly provided Canada's Nuclear Safety Commission written confirmation that all required safety system upgrades were installed by December 31, 2005, and received a renewed license to operate the reactor on that basis. However, two mandated heavy water pumps were not connected to an emergency power supply. The discovery of this fact in November 2007 led to the extension of a routine NRU shutdown affecting Tc-99m sold both by Nordion and by Covidien throughout North America. South Africa provided some back-up supply, but European producers were unable to respond for more than two weeks. By that time, Canadian parliament had passed an emergency measure to order the restart of the reactor and connection of the emergency power supplies. The reactor was restarted on December 16, and production of radioisotopes resumed on December 18. “Backgrounder: Safety Upgrades: Atomic Energy of Canada Limited's National Research Universal Nuclear Reactor,” Canadian Nuclear Safety Commission (CNSC), December 10, 2007, <www.nuclearsafety.gc.ca/eng/newsroom/issues/backg_precis_aecl_iso.cfm>; “CNSC and AECL to Conduct Joint Review of NRU Reactor Events,” February 14, 2008, AECL, <www.aecl.ca/NewsRoom/News/Press-2008/080214.htm>; “MDS Nordion Responds to ‘Canada's Nuclear Fallout’ Article,” CMAJ, February 6, 2008, <www.cmaj.ca/cgi/eletters/cmaj.080154v1>.

2. Shawn McCarthy, “Ottawa Got Early Warning, Firm Says,” Globe and Mail, February 8, 2008.

3. Werner Swart and Melody Brandon, “Nuclear Alert,” The Times (South Africa), November 14, 2007; Michael Wines, “Break-In at Nuclear Site Baffles South Africa,” New York Times, November 15, 2007, p. A3.

4. Another breach approximately two years ago reportedly led to a security upgrade. Micah Zenko, “A Nuclear Site Is Breached: South African Attack Should Sound Alarms,” December 20, 2007, Washington Post, p. A29.

5. “Workshop Report,” Global Initiative to Combat Nuclear Terrorism: Workshop on the Production of Mo-99 Using Low Enriched Uranium, December 2–5, 2007, Sydney, Australia.

6. George Vandegrift, “Primer on Mo-99 Production,” white paper written for the NAS study on the production of medical isotopes without HEU, mandated by Section 630 of the Energy Policy Act of 2005.

7. The Tc-99m can be eluted (milked) from the Mo-99 generator once a day (Mo-99 is retained). The generators lose half their activity every sixty-six hours (the half-life of Mo-99) and are generally replaced once a week. Generators contain 0.5 to 10 curies of Mo-99. Vandegrift, “Primer on Mo-99 Production.”

8. About half of the Mo-99 used in the world is used in nuclear medicine in the United States. Forecasts by producers predict some 5–10 percent growth in U.S. annual demand for Mo-99 over the next decade and 8–12 percent growth in world demand.

9. The world's four major producers use HEU targets, while much of the remaining 5 percent of global Mo-99 production is derived from the irradiation of LEU targets. The targets are essentially mini-HEU fuel plates, where a uranium-aluminum alloy or compound is mixed with aluminum powder and sandwiched between two pieces of aluminum cladding, either flat or cylindrical in form. The number of days of irradiation depends upon the flux of the reactor and other factors, but is generally less than a week. The targets are thus nowhere near as radioactive as spent fuel elements after irradiation. Vandegrift, “Primer on Mo-99 Production.”

10. Producers generally sell Mo-99 by the “six-day curie.” This means they assure that, six days after delivery, the number of curies will decay to no more than the specified amount. Given the sixty-six hour half-life, the producers must actually send about four times the number of curies that will be available six days later. Ibid.

11. For more information on the RERTR program, see the article by William C. Potter and the article by Anya Loukianova and Cristina Hansell in the special section in this issue. For statistics comparing the use of HEU in research reactor fuel and the production of Mo-99, see discussion below as well as the article by Ole Reistad and Styrkaar Hustveit in the special section in this issue.

12. A presentation by experts from Belgium's Institut National des Radioéléments and Nuclear Research Center stated that there would be a “definitive need” for one new reactor in Europe by 2010–2015 for radioisotope production, and a possible need for a second new reactor for this purpose by 2015–2020. Henri Bonet, Bernard David, and Bernard Ponsard, “Production of Mo99 in Europe: Status and Perspectives,” Research Reactor Fuel Management Meeting, Budapest, Hungary, April 2005.

13. PUREX stands for plutonium-uranium extraction. See George Vandegrift, Allen J. Bakel, and Justin W. Thomas, “Overview of 2007 ANL Progress for Conversion of HEU Based Mo-99 Production as Part of the U.S. Global Threat Reduction—Conversion Program,” paper presented at the RERTR 2007 International Meeting, Prague, September 23–27, 2007. According to the calculations in this study, the dose rate per gram of HEU irradiated for five days at a flux of 1x10¹⁴ neutrons per square centimeter (cm) per second drops by nearly five orders of magnitude from the day the target is processed until the end of three years in storage. Calculating dose rates after three years for the two types of processing methods used by major producers, it was determined that for acid-dissolution waste, the dose rate after three years of storage is 1.5 mrem per hour per gram of HEU at 100 cm, with no shielding. For alkaline-digested HEU, the dose rate is 0.5 mrem. Any shielding would considerably lower this dose rate.

14. PUREX stands for plutonium-uranium extraction. See George Vandegrift, Allen J. Bakel, and Justin W. Thomas, “Overview of 2007 ANL Progress for Conversion of HEU Based Mo-99 Production as Part of the U.S. Global Threat Reduction—Conversion Program,” paper presented at the RERTR 2007 International Meeting, Prague, September 23–27, 2007. According to the calculations in this study, the dose rate per gram of HEU irradiated for five days at a flux of 1x10¹⁴ neutrons per square centimeter (cm) per second drops by nearly five orders of magnitude from the day the target is processed until the end of three years in storage. Calculating dose rates after three years for the two types of processing methods used by major producers, it was determined that for acid-dissolution waste, the dose rate after three years of storage is 1.5 mrem per hour per gram of HEU at 100 cm, with no shielding. For alkaline-digested HEU, the dose rate is 0.5 mrem. Any shielding would considerably lower this dose rate.

15. The study by Vandegrift, Bakel, and Thomas uses the spent research reactor fuel dose rate cited in: Raymond B. Pond and James E. Matos, “Nuclear Mass Inventory, Photon Dose Rate, and Thermal Decay Heat of Spent Research Reactor Fuel Assemblies (Rev 1),” paper presented at the RERTR 1996 International Meeting, Seoul, October 6–10, 1996. See also Vandegrift, Bakel, and Thomas, “Overview of 2007 ANL Progress.”

16. Such as RERTR, the U.S. Foreign Research Reactor Spent Nuclear Fuel (FRR SNF) acceptance program, the Russian Research Reactor Fuel Return (RRRFR) program, the Emerging Threats and Gap Material Program, and the Global Research Reactor Security (GRRS) Program. For more information, see the article by Anya Loukianova and Cristina Hansell in the special section in this issue.

17. For a description of security of U.S. HEU and new U.S. requirements, see the article by Anya Loukianova and Cristina Hansell in the special section in this issue.

18. IAEA, “The Physical Protection of Nuclear Material and Nuclear Facilities,” INFCIRC/225/Rev.4.

19. “The Technetium-99m Generator,” Brookhaven National Laboratory, <www.bnl.gov/bnlweb/history/Tc-99m.asp>.

20. “The Technetium-99m Generator,” Brookhaven National Laboratory, <www.bnl.gov/bnlweb/history/Tc-99m.asp>.

21. “Canada's Nuclear History Chronology,” Canadian Nuclear Society, updated March 13, 2008, <www.cns-snc.ca/history/canadian_nuclear_history.html>.

22. “Record of Decision for the Medical Isotopes Production Project: Molybdenum-99 and Related Isotopes,” Federal Register, Vol. 61, No. 181 (September 17, 1996), pp. 48921–48928.

23. S. James Adelstein and Frederick J. Manning, eds., Isotopes for Medicine and the Life Sciences (Washington, DC: National Academies Press, 1995).

24. Kathryn Ostic, “Laboratory Decommissioning Omega West Reactor Starting Next Month,” Los Alamos National Laboratory News Bulletin, May 15, 2002.

25. The Energy and Water Development Appropriations Act of 1990 required isotope production and distribution to be self-supporting as of fiscal 1990. Adelstein and Manning, Isotopes for Medicine and the Life Sciences.

26. J. Rojas-Burke, “The Future Supply of Molybdenum-99,” Journal of Nuclear Medicine 36 (November 1995), pp. 15N, 22N, 35N; Darren G. Talley, “Isotope Production Target Irradiation Experience at the Annular Core Research Reactor,” DOE document, SAND97-0308C (1997); “Record of Decision for the Medical Isotopes Production Project: Molybdenum-99 and Related Isotopes.”

27. Letter from Tom Clements, Nuclear Control Institute, to Colette E. Brown, Office of Nuclear Energy, Science and Technology, DOE , September 18, 2000, <www.nci.org/f/fftf91800.htm>.

28. Adelstein and Manning, Isotopes for Medicine and the Life Sciences.

29. “Record of Decision for the Medical Isotopes Production Project: Molybdenum-99 and Related Isotopes.”

30. “Record of Decision for the Medical Isotopes Production Project: Molybdenum-99 and Related Isotopes.”

31. See December 13, 2007 letter from Rick Lytle, U.S. general manager, Imaging Solutions, Covidien, to Covidien customers regarding the December 2007 shortage, <www.imaging.mallinckrodt.com/_Attachments/Resources/Covidien%20Mo99%20CUSTOMER%20Update%2012-13-07%20Final.pdf>.

32. “Sudden Radioisotope Shortage Threatens Patient Care,” Journal of Nuclear Medicine 49 (January 2008), pp. 17N–18N.

33. McCarthy, “Ottawa Got Early Warning, Firm Says.”

34. Alan Kuperman notes that European and South African reactors typically operate well below capacity, arguing that back-up supplies could have been made available. He has called for a thorough investigation into the November 2007 events. See Alan Kuperman, “Backup Supplies Were Readily Available from Reactors in Europe and South Africa,” Toronto Star, March 1, 2008.

35. Alexandre Deslongchamps, “Atomic Energy Scraps Plans for Isotope Reactors (Update 2),” Bloomberg News, May 16, 2008.

36. “Mallinckrodt Product Clearances Total Nearly 40 Worldwide During 1997,” PR Newswire, February 23, 1998; “Future of Nuclear Medicine, Part 1: Marketing Research Forecasts,” Journal of Nuclear Medicine 39 (February 1998), pp. 27N–28N, 30N.

37. Ian Austen, “Reactor Shutdown Causing Medical Isotope Shortage,” New York Times, December 6, 2007, p. C5.

38. For a brief history of terrorist attacks and insightful assessment of terrorist trends, predicting that terrorist groups are more likely to seek weapons of mass destruction in the future than they were in the past, see Richard Falkenrath, “Confronting Nuclear, Biological, and Chemical Terrorism,” Survival 40 (Autumn 1998), pp. 42–65.

39. “Nuclear Smuggling,” undated, Department of Homeland Security Nuclear Assessment Program, <www.exportcontrol.org/library/conferences/1379/005_Proliferation_Threat_Brief-Nuclear_Smuggling_-_Zachary_K.pdf>.

40. For more information on the Schumer Amendment, see the article by Anya Loukianova and Cristina Hansell in the special section in this issue.

41. U.S. Public Law 102–486 (106 Stat. 2943), October 24, 1992.

42. NRC officials, e-mail correspondence with Scott Parrish, Center for Nonproliferation Studies, May 2005. (Interviews granted on condition of anonymity.)

43. George F. Vandegrift, “RERTR/GTRI Mo-99 Technology-Development History,” Argonne National Laboratory, unpublished paper, April 2007.

44. Vandegrift, “RERTR/GTRI Mo-99 Technology-Development History.”

45. George Vandegrift, “ANL (GFV) Perspective on Conversion of Mo-99 Production from High- to Low-Enriched Uranium,” presentation for the NAS study on the production of medical isotopes without HEU, mandated by Section 630 of the Energy Policy Act of 2005, Argonne National Laboratory, <dels.nas.edu/nrsb/presentations/vandergrift.pdf>.

46. George Vandegrift, “ANL (GFV) Perspective on Conversion of Mo-99 Production from High- to Low-Enriched Uranium,” presentation for the NAS study on the production of medical isotopes without HEU, mandated by Section 630 of the Energy Policy Act of 2005, Argonne National Laboratory, <dels.nas.edu/nrsb/presentations/vandergrift.pdf>.

47. Alan J. Kuperman, “The Global Threat Reduction Initiative and Conversion of Isotope Production to LEU Targets,” paper presented at the RERTR 2004 International Meeting, Vienna, November 7–11, 2004, p. 3.

48. For details about Nordion lobbying and the Burr Amendment, see Alan Kuperman, “Bomb-Grade Bazaar,” Bulletin of the Atomic Scientists, March/April 2006, pp. 44–50.

49. Kuperman, “The Global Threat Reduction Initiative and Conversion of Isotope Production to LEU Targets.”

50. The bill passed the House on July 27, 2005 by 275–156 and the Senate on July 29, 2005 by 74–26. H.R. 6, Energy Policy Act of 2005. It is now known as Public Law 109-58.

51. Energy Policy Act of 2005 (P.L. 109-58).

52. Frank N. von Hippel and Laura H. Kahn, “Feasibility of Eliminating the Use of Highly Enriched Uranium in the Production of Medical Radioisotopes,” Science and Global Security 14 (2006), p. 157.

53. Energy Policy Act of 2005 (P.L. 109-58).

54. NESCA, NECSA Annual Report 2006, p. 35, <www.necsa.co.za/docs/K-4685_NECSA_AnnualReport_2006_LR.pdf>; Nicky Smith, “Second Reactor Mooted,” Financial Mail, November 23, 2007, p. 76.

55. CERCA produces aluminide (UAlx) and silicide (U3Si2) “dispersion” research reactor fuel on the same type of equipment needed to produce dispersed uranium targets. It has already demonstrated laboratory-scale production of these targets, has a partnership with NECSA, and is in talks with Australia's ANSTO. Presentation by Jean Louis Falgoux, Areva vice president, at the Global Initiative to Combat Nuclear Terrorism Workshop on Molybdenum-99 Production Using Low Enriched Uranium, Sydney, Australia, December 2–5, 2007.

56. HFR's share of the global Mo-99 market was about 30 percent and its European market share 60 percent as of 2006. European Commission, “A Joint Undertaking Initiative for the High Flux Reactor,” 2006.

57. Ann MacLachlan, “NRG to Study Potential for use of LEU for Mo-99,” Nuclear Fuel, December 17, 2007, p. 1.

58. Isotope producer IRE, which receives some of its irradiation services at HFR, was apparently unaware of the NRG plan before the Sydney meeting. IRE director Henri Bonet expressed some doubt about the time frame suggested by the HFR director, noting that world Mo-99 demand is increasing and must be met at the same time. Further, he estimated that the new processing facilities that would have to be built to handle LEU targets would cost 50 million–100 million euros. Nevertheless, representatives of all of the major isotope producers agreed at the Sydney workshop that industrial-scale production using LEU targets could be introduced in seven to ten years. Ann MacLachlan, “NRG to Study Potential for Use of LEU for Mo-99.”

59. IAEA, “CRP on Production of Mo-99 from LEU or Neutron Activation,” <www.iaea.org/OurWork/ST/NE/NEFW/nfcms_researchreactors_Mo99.html>.

60. ANSTO plans to increase production from 500,000 doses per year to some 2 million doses per year (just under 10 percent of current world demand). Indonesia is converting to LEU targets in 2008; conversion has been slowed by difficulties obtaining U.S. export licenses for its new LEU targets. Budi Briyatmoko, Sudarmadi Abdul Mutalib, and Bambang Purwadi, “Indonesia's Program for Conversion of Mo-99 Production to LEU Fission,” presentation at the Symposium on Minimization of HEU in the Civilian Nuclear Sector,” Oslo, Norway, June 17–20, 2006; DOE scientist (name withheld at author's discretion), statement at Global Initiative to Combat Nuclear Terrorism: Workshop on the Production of Mo-99 Using Low Enriched Uranium, December 2–5, 2007, Sydney, Australia.

61. MURR produced Mo-99 from neutron activation for domestic use beginning in 1967. It ceased in 1984 when Mo-99 from fission became readily available and the smaller market for neutron activation disappeared. Ralph Butler, director, Research Reactor Center, University of Missouri-Columbia, personal correspondence with author, March 24, 2008.

62. Argonne's George Vandegrift notes that “use of the LEU-foil target in alkaline-digestion processes will reduce liquid waste volumes by at least five times and greatly limit the amount of aluminum hydroxide and column material that must be disposed. In the Cintichem process, lower dissolution volume may generate slightly less waste.” George F. Vandegrift, “Facts and Myths Concerning 99Mo Production with HEU and LEU Targets,” paper presented at the RERTR 2005 International Meeting, Boston, November 6–10, 2005.

63. More than thirty such reactors have been built. Currently, there are homogenous reactors: at Los Alamos (seven reactors) and Oak Ridge (two) in the United States; at IPPE Obninsk (two) and Kurchatov (two) in Russia; at Valduc, France (two critical assemblies); and at JAERI and Tokai (two critical assemblies) in Japan. Alberto Manzini, “Producing Mo-99 from LEU Targets,” presentation at the Symposium on Minimization of HEU in the Civilian Nuclear Sector,” Oslo, Norway, June 17–20, 2006.

64. Russell Ball, “Use of LEU in the Aqueous Homogeneous Medical Isotope Production Reactor,” RERTR 1994 International Meeting, Williamsburg, Virginia, October 1994; Russell Ball, “The Mo-99 Solution,” Nuclear Engineering International 40 (December 1995), p. 42.

65. IAEA Consultancy on Utility of Homogenous Aqueous Solution Nuclear Reactors for the Production of Mo-99 and Other Short-Lived Radioisotopes, “Summary of Presentations, Discussions, Conclusions and Recommendation,” June 20–22, 2007.

66. Russell M. Ball, V.A. Pavshook, and V.Ye. Khvostionov, “Present Status of the Use of LEU in Aqueous Reactors to Produce Mo-99,” RERTR 1998 International Meeting, Sao Paulo, October 1998.

67. The ARGUS experiment also resulted in other useful medical radionuclides (strontium-90 and I-131), increasing the commercial prospects of the method. Roy Brown, president of Nuclear Medicine Solutions (formerly of TCI Medical), e-mail correspondence with author, April 3, 2007.

68. Although a full-scale pilot plant was never developed, there have been many short tracer experiments. Pablo Adelfang, “Symposium on Minimization of HEU in the Civilian Nuclear Sector,” Oslo, Norway, June 17–20, 2006.

69. The National Nuclear Security Administration (NNSA) has supported Argonne research applicable to the development of a solution machine at B&W, which is coordinating its development effort with the national laboratory. In the past, NNSA also funded work at Kurchatov through the Initiatives for Proliferation Prevention (IPP) program. On the latter, see, Roy W. Brown, “Production of Medical Radionuclides at Russian Nuclear Institutes,” presentation at Americas Nuclear Energy Symposium 2002, Miami, Florida, October 16–18, 2002, <anes.fiu.edu/Pro/s4Bro.pdf>.

70. It was noted at the IAEA consultancy on solution reactors that China and Russia are also pursuing radioisotope production at solution reactors. Consultancy participants included representatives of China's Medical Isotope Production Reactor at Chengdu as well as Russia's Kurchatov Institute and Institute for Physics and Power Engineering. See, IAEA Consultancy on Utility of Homogenous Aqueous Solution Nuclear Reactors for the Production of Mo-99 and Other Short-Lived Radioisotopes, “Summary of Presentations, Discussions, Conclusions and Recommendation.”

71. W. Evans Reynolds, BWX Technologies, Inc., telephone interview with the author, April 2, 2007.

72. IAEA Consultancy on Utility of Homogenous Aqueous Solution Nuclear Reactors, “Summary of Presentations.”

73. IAEA Consultancy on Utility of Homogenous Aqueous Solution Nuclear Reactors, “Summary of Presentations.”

74. Official from the IAEA Nuclear Fuel Cycle and Materials Section (name withheld by request), e-mail communication with the author, March 8, 2008.

75. See, for example, presentations at RERTR meetings, as well as Luc Van Den Durpel, et al., “Myrrha: A Prototype Accelerator-Driven System,” Scientific Report 1997, <www.sckcen.be/sckcen_en/publications/scientrep/97/E/E2.shtml>.

76. Ira N. Goldman, Natesan Ramamoorthy, and Pablo Adelfang, “Progress in the IAEA Coordinated Research Project: Production of Mo-99 Using LEU Fission or Neutron Activation,” RERTR 2006 International Meeting, Cape Town, October 2006.

77. CRP T.1.20.18, “Developing Techniques for Small-Scale Indigenous Production of Mo-99 Using LEU or Neutron Activation: In Order [to] Assist Countries to Pursue Such Mo-99 Production,” was initiated with an IAEA Consultants Meeting in Vienna in November 2004 attended by participants from Argentina, Belgium, Canada, Netherlands, South Africa, and the United States, including representatives of the four major commercial producers of Mo-99. The CRP has received both DOE discretionary funding and money from the regular IAEA budget. The DOE made an extrabudgetary contribution to begin the CRP in 2005, and it has been supported from the IAEA regular budget since that time. Goldman, Ramamoorthy, and Adelfang, “Progress in the IAEA Coordinated Research Project: Production of Mo-99 Using LEU Fission or Neutron Activation.”

78. Daniel Cestau, Ariel Novello, Pablo Cristini, Marcelo Bronca, Roberto Centurión, Ricardo Bavaro, Julián Cestau, and Eduardo Carranza, “HEU and LEU Comparison in the Production of Molybdenum-99,” presentation at RERTR 2007 International Meeting, Prague, September 23–27, 2007.

79. Daniel Cestau, remarks on paper presentation at RERTR 2007 International Meeting, Cape Town.

80. George Vandegrift, Argonne National Laboratory, personal correspondence with author, March 27, 2008.

81. Manzini, “Producing Mo-99 from LEU Targets.”

82. Manzini, “Producing Mo-99 from LEU Targets.”

83. S. Balart, O. Calzetta, P. Cristini, J. Garces, A. J. Gauna, A. Gonzales, J.D. Hermida, E. Pasqualini, and H. Taboada, “Progress on RERTR Activities in Argentina,” presentation at RERTR 2006 International Meeting, Cape Town, South Africa, October 29–November 2, 2006.

84. Taboada, remarks during paper presentation at RERTR 2006 International Meeting, Cape Town.

85. Ralph Butler, director, Research Reactor Center, University of Missouri-Columbia, e-mail correspondence with author, March 24, 2008.

86. Construction of a new building at MURR will cost about $35 million. MURR is seeking financing from the University of Missouri, DOE, and industry. With adequate funding, commercial operation could commence in four years. Currently, DOE is funding research and development efforts on a non-proprietary basis only. This includes some $600,000 in support for the MURR demonstration effort, from fiscal 2006 to fiscal 2008, as indicated in Daniel Horner, “Plans for US Isotope Reactors Carry Nonproliferation, Market Impacts,” Nucleonics Week, February 14, 2008, pp. 3–5. It should be noted that the U.S. government currently will not fund any projects if they put other producers at a competitive disadvantage (even if they are in foreign countries or use HEU); thus, it is not clear that MURR can obtain the funding it needs to get operations started from the DOE.

87. Horner, “Plans for US Isotope Reactors Carry Nonproliferation, Market Impacts.”

88. This point was made by MURR director Ralph Butler in Horner, “Plans for US Isotope Reactors Carry Nonproliferation, Market Impacts.”