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Tom Bielefeld

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Tom Bielefeld

Associate, Project on Managing the Atom




Tom Bielefeld is an associate with the Belfer Center's Project on Managing the Atom. His work focuses on nuclear security and non-proliferation as well as on terrorism prevention.

Bielefeld is a physicist specializing in security policy research and analysis. He joined the Harvard Kennedy School's Belfer Center for Science and International Affairs as a Research Fellow in 2006. Previously, he had held research positions at the Bremen State Radioactivity Measurements Laboratory and at Hamburg University's Institute for Peace Research and Security Policy (both in Germany). He was also the co-founder of the Bremen Institute for Technology and Society as well as a Research Affiliate with the Science, Technology, and Global Security Working Group at MIT.

Bielefeld holds a Master of Science degree in theoretical particle physics from the University of Wales Swansea. He is currently pursuing a doctorate in physics with the University of Bremen on "Studies in Nuclear Security: Preventing and Preparing for Nuclear and Radiological Terrorism."



By Date



Marco Ugarte, via AP

January 23, 2014

"Mexico’s Stolen Radiation Source: It Could Happen Here"

Op-Ed, Bulletin of the Atomic Scientists

By Tom Bielefeld, Associate, Project on Managing the Atom

Although the truck-jacking of highly radioactive material outside Mexico City on December 1, 2013 ended without the worst case materializing, it should serve as a wakeup call, not just in Mexico but also in the United States and elsewhere. Dangerous radiation sources remain vulnerable to theft, especially when they are out on the road. There is also poorly protected radioactive material in hospitals and other facilities. Improving security requires tougher regulations and greater risk awareness in the industry. Unfortunately, the United States is no exception, so it’s time for the country to get serious about locking up its radioactive material.



July 2010

"Krypton Gas Cylinders as a Source of Radiation"

Journal Article, Health Physics, issue 1, volume 99

By Helmut W. Fischer, Tom Bielefeld, Associate, Project on Managing the Atom and Bernd Hettwig

Helmut W. Fischer, Tom Bielefeld, and Bernd Hettwig's article "Krypton Gas Cylinders as a Source of Radiation" was published in Health Physics. Their article proposes to improve labeling and documentation standards for cargo shipments of pressurized krypton gas.



June 2010

"85Kr in Industrial Krypton Gas: Origin, Identification and Dosimetry"

Conference Paper

By Helmut W. Fischer, Bernd Hettwig and Tom Bielefeld, Associate, Project on Managing the Atom

Helmut W. Fischer, Bernd Hettwig, and Tom Bielefeld presented "85Kr in Industrial Krypton Gas: Origin, Identification and Dosimetry" at the Third European IRPA Congress in June 2010.  They reported on a case of transcontinental transport of krypton gas, triggering of a radiation alarm and subsequent in situ measurement by different radiometric techniques.



AP Photo

April 12, 2010

"A Call for German Leadership in Combating Nuclear Terrorism"


By Rolf Mowatt-Larssen, Senior Fellow, Belfer Center for Science and International Affairs and Tom Bielefeld, Associate, Project on Managing the Atom

"...Germany has an opportunity at the Washington summit — and thereafter — to step up and lend non-American leadership to the problem. Recognizing that in many of the world's capitals the threat of nuclear terrorism is not yet being taken seriously, and when in some of them the very notion is even considered an American pretext for an entirely different, potentially hostile political agenda, non-American leadership is most urgently needed."




November 20, 2008

"Nuclear Forensics and Its Role in Security Policy"


By Tom Bielefeld, Associate, Project on Managing the Atom

Nuclear forensic analysis is currently discussed as a potentially important new tool to prevent nuclear terrorism by enabling investigators to attribute nuclear materials to their production facility and thus deterring potential state actors from transferring such materials to terrorists. In the seminar, an introduction into the technical possibilities and limitations of pre- and post-attack nuclear forensics will be given, based entirely on open source analysis. This will be followed by a discussion about the roles that nuclear attribution can — or cannot — play in security policy.



Petr Pavelicek/IAEA

July 17, 2008

"The Security of Medical and Industrial Radioactive Sources"

Conference Paper

By Tom Bielefeld, Associate, Project on Managing the Atom and Helmut W. Fischer

Recent foiled and successful terrorist plots in Europe and the US (including two cases in the UK and Germany which included plans to design radiological dispersal devices in 2004 and 2005), clearly demonstrate that domestic or locally acting terrorist cells have become an important part of the terrorist threat picture. The uncovered “dirty bomb” – plots involved radioactive material of type or quantity that would not have caused much damage. Still, these observations underscore the necessity to revisit the issue of radioactive sources security in countries which may become the target of a radiological attack. This includes in particular countries in Europe, many of which in the past relied on sophisticated — but safety centred — regulations and functioning oversight institutions.



July 2007

"Reducing Nuclear and Radiological Terrorism Threats"

Conference Paper

By Matthew Bunn, Professor of Practice; Co-Principal Investigator, Project on Managing the Atom and Tom Bielefeld, Associate, Project on Managing the Atom

Urgent actions are needed to prevent a nuclear or radiological 9/11.  Terrorists are actively seeking nuclear weapons and Radiological Dispersal Devices (RDDs) and the materials to make them.  There are scores of sites where the essential ingredients of nuclear weapons exist, in dozens of countries worldwide.  There are thousands of sites worldwide where radiological materials exist.  Many of these sites are not sufficiently secured to defeat the kinds of threats that terrorists and criminals have demonstrated they can pose.  A dangerous gap remains between the urgency of the threat of nuclear and radiological terrorism and the scope and pace of the U.S. and world response.  While the gap has narrowed significantly in recent years, much more needs to be done.  This paper describes the nuclear and radiological terrorism threats, analyzes the actions taken so far to address these threats, and recommends further actions going forward.



July/August 2007

"The Khan Job"

Magazine or Newspaper Article, Bulletin of the Atomic Scientists, issue 4, volume 63

By Tom Bielefeld, Associate, Project on Managing the Atom and Hassan Abbas, Former Senior Advisor, Belfer Center for Science and International Affairs

Tom Bielefeld and Hassan Abbas review Der Physiker der Mullahs (The Mullah's Physicist), a film by Egmont R. Koch, broadcast on German Public Television (WDR) on February 22, 2007.



Spring 2007

"Security and Damage Potential of Commercial Radioactive Sources"

Journal Article, Journal of Nuclear Materials Management, issue 3, volume 35

By Tom Bielefeld, Associate, Project on Managing the Atom and Helmut W. Fischer

MTA/ISP fellow Tom Bielefeld and his co-author Helmut Fischer focus on the problem of protecting radiological sources, preventing a “dirty bomb” attack, and putting measures in place to mitigate the effects should an attack occur.



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