Summary of the 2nd International Symposium on HEU Minimization

Summary of the 2nd International Symposium on HEU Minimization

Want to dive deeper?

Visit the Education Center

Co-hosted by the Governments of Austria and Norway and NTI, in cooperation with the IAEA, the 2nd International Symposium on HEU Minimization took place in Vienna January 23-25, 2012.

Building on the results of the first Symposium in Oslo in 2006, the Vienna Symposium revisited the issue of highly enriched uranium (HEU) minimization, reviewed the progress made and scope of efforts to date, remaining challenges and possible new measures to address them. Support for minimization of civilian HEU is growing – this has been reflected at the 2010 Nuclear Non-Proliferation Treaty review conference and the 2010 Nuclear Security Summit.  The Symposium took place January 23-25, 2012 and focused attention on HEU minimization in the civilian nuclear complex around the world, provided realistic policy discussion and elaboration, and facilitated a dialogue about national and international efforts to minimize and eventually eliminate the use of HEU in the civilian sector.

Norwegian Ambassador Jan Petersen opened the Symposium by emphasizing the objective to minimize HEU in the overall context of creating a safer world free from nuclear weapons. While recognizing that nearly all the HEU in the world is for military use, the quantities in civilian use are still sufficient to constitute a considerable threat should they be acquired or re-directed for non-peaceful purposes. HEU minimization is important as a non-proliferation concern, to advance international cooperation on the peaceful uses of nuclear energy and to support nuclear disarmament.  Therefore, the International Atomic Energy Agency (IAEA) plays an essential role in verification and promoting accountability, safety and security of peaceful applications of nuclear technology globally.

Following the speech by Ambassador Petersen, the following topics were discussed in six panels:

Summary of Symposium Discussions

The use of HEU for a host of civilian and military purposes poses real safety and security risks and time is not on our side. Large amounts of HEU for civilian and military purposes exist in many countries.  The bulk of this HEU is  located in the US and Russia, though significant stockpiles are also found in many other states. Great progress in minimization of HEU stocks and utilization has been achieved in the past decade, including the conversion of HEU-fueled reactors to LEU, cooperative efforts such as the US-Russian HEU blend-down program (Megatons to Megawatts) and the Material Conversion and Consolidation Program have achieved important successes. But many challenges remain.

Considerable attention was given to the use of HEU as part of research facilities, propulsion vessels and in stocks, both in the civilian and military non-explosive areas. There is overall agreement that there are more than 100 remaining HEU-fueled facilities globally and that hundreds of kilograms of HEU are used annually in civilian facilities. Other fuel cycle activities that handle HEU at additional sites and locations, such as fuel manufacturing, transport and waste handling, represent an important additional challenge.

One of these key challenges is to fully understand the scope of the problem.  This can be improved through transparency. There is no mandatory transparency regime or regular public declarations regarding civil HEU stockpiles, although all non-nuclear weapons states provide confidential reporting under their IAEA safeguards agreements.  France, Germany and the UK provide civil HEU declarations for publication by the IAEA as an addendum to their voluntary INFCIRC/549 civil plutonium declaration. Until there is a norm for increasing  transparency of civilian HEU holdings, voluntary declarations by all states with HEU should be encouraged.  One additional challenge with regard to transparency is how to include military non-explosive stockpiles.  It may be advisable to include in HEU declarations the inventories of material resulting from nuclear disarmament, material declared excess to defense needs and material in active and reserve stockpiles for military, naval propulsion.

Another challenge is determining the right balance between HEU removal and increasing security for material in place. While conversion and removal activities can create increased security risks through changes in material forms and transport requirements, these must be weighed on a case-by-case basis against the longer term risk reductions generated by the consolidation and elimination of such material.  Efforts to remove, eliminate, or consolidate HEU holdings should be carried in a manner that provides the highest level of security for this material, including during its transportation.

There have been great successes – even breakthroughs – in HEU minimization in the last five years.  Many research reactor facilities, including those in Romania and Uzbekistan have successfully moved to LEU cores with the active financial and technical support of programs in the US and Russia.  These cases reflect the important foundational elements of a successful research reactor conversion effort:  effective legal and regulatory frameworks, active support and positive decision making of the government and facility operator, international cooperation, qualified national and international experts to manage the process, and the assistance of the IAEA.  It is important to remember that reactor conversion and fuel removal efforts often span multiple administrations.  Therefore, a deliberate campaign to build a broad constituency of support, including in the public through the media, can be important. 

There has been significant progress on conversion of molybdenum-99 – or “moly-99” – production processes as well.  All major commercial suppliers have made the political commitment to convert their facilities and processes to use LEU before 2015, and Australia (through a technology partnership with Argentina) has led the way in developing the capacity to become a commercial producer of LEU-based molybdenum-99.  It is advisable to convert current uranium fission-based processes from HEU to LEU using variations of existing technologies while new approaches like neutron activation and solution reactors are developed and assessed for their potential.

The economics are not yet clear regarding conversion decisions, and this is partly due to the lack of real cost recovery in past moly-99 production activities.  In order to make educated decisions about the impact of introducing LEU based moly-99, it is important to undertake, as the OECD is doing now, a full cost assessment all along the molybdenum-technetium supply chain.  The pace, scale, timing, and scope of conversion efforts have commercial and economic impacts that must be understood, and may also effect reliability of supply.  Reliability of fuel and target material is a conversion driver because a predicted future difficulty in procuring HEU for medical isotope production may influence a positive decision to convert in order to avoid supply interruptions.  However, unreasonable fears about the unreliability of material suppliers should not be used to justify potentially problematic fuel cycle decisions. 

It is also important to assure that predictable regulatory regimes are supportive of LEU-based moly-99 production approaches so that the assurance of supply is maintained.  Countries should be prepared to facilitate the timely licensing of both LEU-based production processes and the medical isotopes that are produced. In this area, international cooperation is critical and it is important to recognize the linked relationships and coordinate different players, including different nationalities and among the public and private sectors. 

The US and Russia have a special responsibility for HEU minimization because they possess more than 90 percent of the global HEU stockpile and operate more than 50 percent of the HEU-fueled research reactors.  They have also provided most of the HEU research reactors around the world and the material to fuel them.  Important progress has been made as both countries have facilitated major reactor conversion and fuel take-back efforts, and have engaged in efforts to consolidate their nuclear complexes.  In particular, the US Department of Energy’s Global Threat Reduction Initiative (GTRI) has  facilitated the conversion or shut down of 38 reactors since 2004 and is developing new LEU fuels for reactors that cannot be converted with existing fuels.

But there is still a great deal of work to do in the United States and Russia, including making policy decisions that take perceived risk into account. HEU is still used by facilities within the traditional scope of the RERTR and many facilities– e.g. critical assemblies and pulsed reactors – do not have viable conversion or shut down paths.  In addition, HEU is still used by facilities outside the traditional scope of RERTR and the reactors that remain to be converted are the most technically challenging. However, while these challenges do exist for certain facilities, particularly high-flux reactors and reactors with unique fuel designs, conversion is possible in almost all instances, provided that the fuel in development is properly qualified.  It is important to note that for conversion to be sustainable, operators must be confident that post-conversion performance objectives for the reactors will be met. Work done to date suggests that conversion, in almost all cases, does not degrade performance. It is more difficult to ensure operator and government commitment to the HEU minimization objective due to competing pressures such as increased costs, the length of time required to complete the conversion mission and operational and regulatory uncertainty.

The US and Russia must now broaden and accelerate existing programs to incorporate additional facilities and materials and also broaden policy approaches and incentives across the spectrum of HEU minimization programs. In addition, it would be valuable if Russia develops a strategic plan on nuclear science and technology to determine how many research reactors and critical assemblies are needed to enable the state’s overall scientific mission, in order to ensure that HEU minimization programs have forward momentum, are sustainable, and irreversible.

Outside of the United States and Russia, significant challenges to the HEU minimization agenda also remain.  There are a smaller number of facilities that await feasible conversion strategies, but those that remain outside current conversion plans pose the greatest challenges.  With regard to some of these facilities, conversion remains a question of priorities.  If the decision is made that no sacrifice in performance metrics is acceptable, it becomes difficult to imagine conversion decisions before new fuels under development are available.  Therefore, in considering conversion, we must ask: How much performance is enough? Is more always better?  In some very limited cases it might be necessary to envision a layered policy approach that might include:

  • pursuing a commitment to reduce enrichment as far below weapons grade as possible,
  • an ongoing assessment of real performance needs of the facility,
  • a firm commitment to continued development of LEU fuels in the meantime, and
  • a commitment to convert as soon as feasible. 

In other types of HEU-based facilities in some countries, such as the fast critical assembly in Japan, there is a lack of strategic direction regarding the current use and future need for the facility.  Reduced enrichment below weapons grade may be advisable for these facilities as well, in advance of a full conversion to LEU or a decision to shut down.

International cooperation is vital to HEU minimization efforts.  For example, the US’s Global Threat Reduction Initiative (GTRI) is an example of one country working bilaterally with other states to reduce HEU in research reactors and production of medical isotopes and facilitating international collaborative efforts on issues such as new fuel developments and material removals. Some international activities are intended to create an incentive for the use of LEU-based products and processes, e.g  only purchasing medical isotopes made from LEU.  Other efforts focus on the reduction and removal of HEU.  States should take on more visible, active roles in both bi- and multilateral minimization efforts.  

The IAEA works with member states around the world, upon request, to convert HEU-fueled research reactors, convert medical isotope production processes from using HEU to LEU, and assist member states in repatriating spent and fresh HEU reactor fuel to its country of origin.  This work should be supported and expanded, where possible. There are multiple paths that might be pursued to continue international HEU minimization efforts:

  • Prioritizing and addressing the threats that are considered most serious
  • Dealing with the states and programs that have the most material in an effort to reduce those amounts
  • Finding the areas that are easiest to work on, the “low-hanging fruit,” technically and politically.

Current HEU minimization goals are driven primarily by security concerns.  While most states are aware of work on HEU minimization, nuclear security does not have the same drivers – for example, a major, catastrophic event – that has motivated improvements in nuclear safety.  One of the major contributions that international organizations and NGOs can make to these efforts is providing forums for discussion about HEU security.  One specific measure is implementation of an international security accreditation – such as that being developed by the World Institute for Nuclear Security (WINS) – that would ensure HEU remaining at a site is adequately secured. 

High level policy commitments guide practical HEU minimization efforts.  For several States, political considerations related to the implementation of the action plan from the 2010 Nuclear Non-Proliferation Treaty review conference, UN Security Council resolutions, and commitments made within the Nuclear Security Summit (NSS) process, are important drivers for HEU minimization. Unofficial discussions, such as the 2006 Oslo Symposium have developed recommendations that are pursued by governments.  It is vital that future meetings, such as the 2012 Seoul Nuclear Security Summit, build and expand these efforts and move the agenda forward in concrete ways.

For example, Ukraine – in addition to its decision to renounce nuclear weapons in the 1990s – has also committed, with IAEA support, to remove all stocks of HEU.  The United States has used the NSS to expand its decades-long commitment to HEU minimization and to build and expand international partnerships on these efforts.  Political commitments at the highest levels in these two countries, and in many others, are vital for sustained HEU minimization success.  It is necessary to build on these successes by engaging countries outside the NSS and NPT processes.

Some proposed and existing measures complement HEU minimization efforts.  Some countries may consider a voluntary commitment to not possess any HEU or separated Plutonium 239.  A further step would be to establish a national or regional “zone free of nuclear weapons usable material.”   Also, multilateral fuel assurance mechanisms, like the IAEA’s International Nuclear Fuel Bank, help support the NPT’s objectives of facilitating the peaceful uses of nuclear energy and supporting global nuclear nonproliferation, while not constraining any state’s right to the peaceful benefits of nuclear energy.  Similarly, complying with the IAEA’s expanding nuclear security and safety framework, including the Convention on the Physical Protection of Nuclear Material and its amendment, INFCIRC/225/ revision 5, and other security and safety related instruments, helps in reducing risks of terrorist incidents and of accidents while increasing the confidence of the international community.  At the regional level, examples of close cooperation exist in Europe and Latin America.

Policy Ideas and Recommendations from the Symposium Co-Hosts

These may not be universally shared by all the Symposium participants, but they reflect a possible policy agenda moving forward.  They aim to promote tangible progress, as well as a culture of transparency, trust and cooperation in the peaceful uses of nuclear energy that also ensures the highest level of safety, security and nonproliferation.

HEU Minimization

  1. Continue to convert HEU-based facilities and processes, remove material from as many countries and locations as possible, and ensure the highest levels of security wherever these materials remain.
  2. Finish the miniature neutron source reactor (MNSR) conversion process, recognizing that politically difficult locations make such activities challenging but also necessary.
  3. Consider additional incentives for conversions and removals.
  4. Establish an internationally agreed norm that LEU will be used in place of HEU in any new facility or process under development, design or construction (including in possible new applications such as space reactors).
  5. For facilities for which LEU fuels are not yet available, secure commitment to reduce enrichment below weapons grade and to the lowest level possible, until such time as LEU fuel can be qualified.
  6. Develop an international, cooperative research and development program to examine options for the management of spent fuel from newly developed LEU fuel types resulting from conversion efforts.
  7. Encourage security requirements that correspond to material types, and demonstrate where conversion to LEU assists in lowering security costs, in order to encourage conversion decisions.
  8. Encourage member states of the IAEA to recognize and support the expertise and capacity of the Agency to further assist international HEU minimization endeavors.

Civilian Naval Propulsion Reactors

  1. Establish a global norm that LEU will be used in place of HEU in any new nuclear-powered civilian vessels.
  2. Phase out or convert existing HEU fuelled civilian vessels.


  1. Develop international standards or guidelines for public declarations of HEU inventories on a regular basis with consistent form and content.
  2. Encourage the voluntary declaration of HEU inventories globally, and in particular, given the large quantities, the declaration of more HEU to be excess to military needs (including from naval programs) and commit to blend down material declared to be excess.
  3. Promote and support independent efforts that add to public understanding of facilities and stocks.

Expansion of Efforts

  1. Expand the scope of conversion efforts to include critical assemblies and pulsed reactors
  2. Recognizing the challenges, begin a conversation on assessing inventory needs for ongoing use of HEU in military vessels and conduct a feasibility study to allow for possible LEU based vessels for future generations of submarines and aircraft carriers.
  3. Shift the focus of international dialogue from HEU minimization to the elimination of civilian uses of HEU.


The fundamental goal of HEU minimization is to enable a path toward a safer world.  The proceedings of the 2nd International Symposium on Highly Enriched Uranium Minimization show that, while there may remain differences on pace and priority, there is a robust and growing consensus on the principle.  It is the responsibility of all stakeholders to seize the moment, broaden the consensus and make commitments irreversible. 

Stay Informed

Sign up for our newsletter to get the latest on nuclear and biological threats.

Sign Up

The NTI Nuclear Security Index


The NTI Nuclear Security Index

The NTI Index is recognized as the premier resource and tool for evaluating global nuclear and radiological security.

Tutorial on Nuclear and Radiological Security

Teaching Tool

Tutorial on Nuclear and Radiological Security

Nuclear and radiological security aims to ensure nuclear and other radioactive materials are secure from unauthorized access and theft, and that nuclear facilities are secure from sabotage.


My Resources