Ambivalent nuclear technologies use or have a potential to produce nuclear weapon relevant materials like highly enriched uranium (HEU), plutonium, tritium and U233. It is important to assess the proliferation potential and measures to strengthen the proliferation resistance of these technologies as early as possible (preventively) to find alternative more proliferation resistant designs or at least to identify sensitive parameters or even critical parts that should trigger international safeguards and export controls.

The conclusions of different case studies investigating the proliferation resistance of nuclear technologies such as spallation neutron sources, tokamak fusion reactors and plutonium fuels will be briefly presented. The main part of the talk will focus on the minimization or elimination of civil HEU usage and the role of research reactor conversion to the use of low enriched uranium, which is intrinsically more proliferation resistant. The conversion of the German high flux research reactor FRM-II will serve as an example for the complex political and technological challenges and problems one has to face, especially, if proliferation concerns are not taken seriously in the research and design phase. These case studies of relatively disparate nuclear technologies have in common that they are neutron producing technologies and some questions regarding their proliferation potential can be addressed using neutronic codes.

Finally, the talk will briefly outline the future research of the next year addressing centrifuge technology as another case study to explicate on exemplary basis general criteria for the proliferation resistant use of nuclear technologies.

Matthias Englert is a postdoctoral fellow at CISAC. Before joining CISAC in 2009, Matthias was a researcher at the Interdisciplinary Research Group Science Technology and Security (IANUS) and a PhD student at the department of physics at Darmstadt University of Technology in Germany. 

His major research interests include nonproliferation, disarmament, arms control, nuclear postures and warheads, fissile material and production technologies, the civil use of nuclear power and its role in future energy scenarios and the possibility of nuclear terrorism.  His research during his stay at CISAC focuses primarily on the technology of gas centrifuges for uranium enrichment, the implications of its use for the nonproliferation regime and on technical and political measures to manage the proliferation risks. 

Matthias has been participating in projects investigating technical aspects of the concept of proliferation resistance with topics spanning from conversion of research reactors, uranium enrichment with gas centrifuges, reducing plutonium stockpiles with reactor based options,  spallation neutron sources and fusion power plants. Further research topics included fissile material stockpiles, fuel-cycles and accelerator  driven systems. Although a substantial part of his professional work of the last years was quite technical he is equally interested in and actively studies the historical, social and political aspects of the use of nuclear technologies. Research interests include the dispute about Article IV of the NPT, the future development of the NPT regime, possibilities for a nuclear weapon free world, preventive arms control, and history and development of proliferation relevant programs. By studying contemporary theory in philosophy of the interaction of science, technology and society, Matthias acquired analytical tools to reflect on approaches describing or addressing the problem of ambivalent technology.

Matthias is a vice speaker of the working group Physics and Disarmament of the German Physical Society (DPG) and a board member of the  German Research Association for Science, Disarmament and Security (FONAS).

Michael May is Professor Emeritus (Research) in the Stanford University School of Engineering and a senior fellow with the Institute for International Studies at Stanford University. He is the former co-director of Stanford University's Center for International Security and Cooperation, having served seven years in that capacity through January 2000. May is a director emeritus of the Lawrence Livermore National Laboratory, where he worked from 1952 to 1988, with some brief periods away from the Laboratory. While there, he held a variety of research and development positions, serving as director of the Laboratory from 1965 to 1971. May was a technical adviser to the Threshold Test Ban Treaty negotiating team; a member of the U.S. delegation to the Strategic Arms Limitation Talks; and at various times has been a member of the Defense Science Board, the General Advisory Committee to the AEC, the Secretary of Energy Advisory Board, the RAND Corporation Board of Trustees, and the Committee on International Security and Arms Control of the National Academy of Sciences. He is a member of the Council on Foreign Relations and the Pacific Council on International Policy, and a Fellow of the American Physical Society and the American Association for the Advancement of Science. May received the Distinguished Public Service and Distinguished Civilian Service Medals from the Department of Defense, and the Ernest Orlando Lawrence Award from the Atomic Energy Commission, as well as other awards. His current research interests are in the area of nuclear and terrorism, energy, security and environment, and the relation of nuclear weapons and foreign policy.

Joseph H. Carens is Professor of Political Science at the University of Toronto (Ph.D., Yale). He is the author of Culture, Citizenship and Community: A Contextual Exploration of Justice as Evenhandedness (OUP: 2000) as well as three other books and more than 60 articles or book chapters. He is currently writing a book on the ethics of immigration, tentatively titled Who Belongs? Immigration, Democracy and Citizenship.

Abstract
In this paper (which is a chapter from a book manuscript on the ethics of immigration), I explore the principled challenges to open borders that grow out of concerns for community. I begin with the claim that our moral commitments to freedom and equality apply only within the boundaries of the state. Next I consider the relationship between sovereignty and immigration. I then turn to the threats that some say free movement would pose to national security, to democratic values, and to public order. After that, I consider the argument that opening borders fails to give the priority that is due to compatriots. Next, I ask whether preservation of a welfare state might make limits on immigration morally permissible. Then I consider whether the desire to maintain a shared culture can justify restrictions on immigration. Finally, I take up the argument that free movement is incompatible with communal self-determination and with the shared responsibility that flows from collective self-governance and sustains it.

Spoiler alert. I think that none of these objections succeeds in undermining the fundamental case for open borders.