Highly enriched uranium: Less is more

International initiatives to reduce the use of highly enriched uranium (HEU) deserve unconditional support, but conversion to low-enriched uranium (LEU) is often a difficult project. Research reactors employ a variety of designs and are used for wide-ranging purposes, and different countries have different views on how conversion should be accomplished. In my own nation of Kazakhstan, preliminary plans are in place to convert three research reactors to LEU fuel. But progress has not been as fast as it might have been.

Why? To answer this, one must understand the bureaucracy surrounding Kazakhstan's research reactors, all of which are owned and operated by government entities. Two of the country's four research reactors, known as IVG and IGR, are owned by the National Nuclear Center and operated by one of the center's divisions, the Institute of Atomic Energy, which is also my employer. A third reactor is owned by the Institute of Nuclear Physics, which is separate from the National Nuclear Center. A fourth reactor is in extended shutdown, with its fuel unloaded, and is of no interest from a conversion perspective.

Conversion to LEU must be approved by two government bodies — the Atomic Energy Agency, which regulates reactors and oversees issues like licensing and safety, and also the Ministry of Industry and New Technologies. The ministry has given its approval for conversion at the IVG and IGR reactors. But the Atomic Energy Agency (soon to be reorganized as the Committee of Atomic Energy) has not. The agency will only give its approval for conversion if the facilities' chief designer and research manager approve changes to the reactors; Kazakh laws and regulations require, for decisions such as LEU conversion, the involvement of each reactor's chief designer and research manager.

And here things get even more complicated, because the reactors' chief designer and research manager are not Kazakh entities. Rather, because of the reactors' Soviet origins, they are government-owned Russian entities that now play a minimal role in the reactors' operation. More to the point, the actions of the chief designer and research manager have, up until now, not been coordinated by any single entity in Russia, leaving the Institute of Atomic Energy to coordinate among them. But it is beyond the institute's capacity to coordinate the actions of entities in another country.

It is useful here to recall the organizational structure that was utilized when research reactors were first established in Kazakhstan. All work was carried out under the unified leadership of the Soviet ministry in charge of nuclear science, energy, and industry. The research manager, chief designer, and operating organization were all part of this ministry, and were connected to one another through a clear set of obligations and responsibilities. This system of interaction helped create the most advanced scientific and industrial sector in the Soviet Union, and one of the most advanced nuclear power industries in the world. Unfortunately, the Kazakh government in general, not to mention the Institute of Atomic Energy itself, lacks the capabilities that the former Soviet ministry possessed.

Faced with all this, representatives of the Global Threat Reduction Initiative, a US project involved in HEU minimization, have attempted to engage with yet another entity, the Russian manufacturer of the reactors' fuel. The idea is that the fuel provider could develop an LEU fuel that would enable the reactors to convert. But this, though it might solve some technical problems, would not solve the bureaucratic problems. The full involvement of the chief designer and research manager would still be required.

The Institute of Atomic Energy is now attempting to circumvent these problems by negotiating with the reactors' fuel provider, in the hope that the fuel provider will take responsibility for coordinating among all Russian entities involved. Indeed, at the Kazakh research reactor operated by the Institute of Nuclear Physics, the conversion effort is proceeding more smoothly, precisely because a Russian, state-owned fuel producer is coordinating among all the relevant Russian entities.

The ideal solution for Kazakhstan's conversion process might have been for representatives of the US government to liaise more with officials in Russia, encouraging the Russian government to take a real interest in the work — to take responsibility for all aspects of the conversion process that involve the competencies of the Russian research manager, chief designer, and fuel manufacturer. In the end, conversion may go forward without that sort of intergovernmental cooperation. But in any event, the Kazakh conversion experience provides an example of the problems that reactors can face while attempting to minimize their use of highly enriched uranium.

About 85 percent of all diagnostic nuclear medical procedures, amounting to 30 million procedures a year, utilize technetium 99, a metastable medical isotope. This is the decay product of molybdenum 99, which is considered the most important radioisotope employed in nuclear medicine.

Molybdenum 99 can be produced in several ways, but the most efficient means for medical applications is the fission route — using thermal neutrons produced in a nuclear reactor to irradiate targets that contain uranium. This results in the splitting (or fission) of uranium atoms into various stable and radioactive isotopes, one of them being molybdenum 99. This isotope is ultimately transported to manufacturers of technetium 99 generators, which deliver the generators to nuclear medicine centers. There, technetium 99 is employed to label molecules for use in diagnostic procedures.

Either highly enriched uranium (HEU) or low-enriched uranium (LEU) can be used as the target (the material at which neutrons are fired to induce fission in the reactor core). Use of HEU carries inherent risks for nuclear proliferation and terrorism. Using LEU reduces these risks significantly.

High to low. Argentina's National Atomic Energy Commission (CNEA), which is responsible for carrying out nuclear research and development and also for applications and services like radioisotope production, began producing molybdenum 99 in 1985, using targets enriched to more than 90 percent in the isotope 235. During 1988 and 1989, the commission's RA-3 reactor — then as now the most important reactor in Latin America for producing radioisotopes — was converted to rely on LEU fuel in order to address international proliferation concerns. The next step in HEU minimization was to develop a procedure for molybdenum production using low-enriched uranium targets.

The first challenge was to develop a suitable LEU target that would yield at least as much molybdenum as was obtained using the HEU target. Toward that end, a joint project was carried out by the groups at CNEA responsible for fuel elements, target manufacturing, and chemical processing of targets for separation and purification of molybdenum. Several uranium compounds were tested until, finally, an LEU target was developed with geometry similar to that of the former HEU target but with higher uranium content.

To begin using these new targets, several changes were required in the facility's separation and purification processes, but only slight modifications in infrastructure were needed. In 2002, commercial production of molybdenum 99 from LEU targets began. The entire conversion project had been carried out by the commission's staff, with no external technical or financial support. Today, CNEA produces high-quality molybdenum 99 that meets all of Argentina's demand and one-third of Brazil's. Additionally, around 15 percent of the molybdenum 99 produced is exported to the Latin American region beyond Brazil in the form of technetium 99 generators.

The Argentine experience with conversion from HEU to LEU has often been presented internationally as evidence that conversion is technically and economically feasible. Examples include a 2009 study mandated by the US Congress, "Medical Isotope Production without Highly Enriched Uranium"; the publications of the High-Level Group on Security of Supply of Medical Radioisotopes, an initiative that addresses global supply issues and also conversion to LEU targets in fission radioisotope production; and the US Energy Department program known as Reduced Enrichment for Research and Test Reactors.

CNEA's current efforts to build a new research and production reactor, as well as a new fission radioisotope production plant with a higher capacity, will help increase the availability of medical radioisotopes produced with LEU targets. This will help avert supply crises for technetium 99 — in 2009, problems at a Canadian technetium facility helped spark such a crisis — and will also contribute to the global initiative for minimization of highly enriched uranium.

Encouraging conversion. International efforts to minimize the use of HEU in the civilian sector are moving in the right direction. Several initiatives mentioned above are powerful instruments for publicizing the feasibility and importance of conversion to LEU; so are efforts by the International Atomic Energy Agency to coordinate meetings and establish research projects on this subject. On a national level, countries with a strong demand for fission molybdenum products should demonstrate a preference for suppliers that use LEU and impose restrictions on products based on HEU.

CNEA has contributed strongly to the conversion process — not only by converting its RA-3 and RA-6 reactor cores and its molybdenum 99 production process to LEU, but also by successfully transferring to entities abroad its LEU production technology. These include the Australian Nuclear Science and Technology Organisation and the Atomic Energy Authority of Egypt.

Taken together, national and multilateral efforts are helping to create a better understanding of the importance of eliminating HEU in civilian applications. This contributes to making the world a safer place.

Controlling access to fissile material is among the most important measures that can be taken to prevent nuclear weapons proliferation, and it is widely recognized that highly enriched uranium (HEU) poses proliferation threats whether it is used in military or civilian applications. This accounts for the international drive to favor low-enriched uranium (LEU) over highly enriched uranium. But what challenges face developing countries that elect to pursue HEU minimization?

In the developing world, highly enriched uranium is put to two uses that are relevant to minimization initiatives: as fuel for research reactors that have not yet been, or cannot be, converted to LEU, and as targets that bear fissionable uranium for the production of medical radioisotopes. (Two other uses may come under discussion in the future: fuel for naval reactors and fuel for fast reactors.)

Organizations that promote conversion to low-enriched uranium, such as the US National Nuclear Security Administration (NNSA) and the International Atomic Energy Agency (IAEA), sometimes employ a carrot-and-stick approach to encourage developing nations to convert. As a stick, these organizations might brandish the idea that developing countries will lose their supplies of enriched uranium if they don't convert to LEU. As a carrot, they might offer developing nations support for research and development initiatives or the chance to export radioisotopes. Many developing countries, in response to political pressure or commercial restrictions, and in an effort to be internationally cooperative, are attempting to reduce their use of HEU as much as is feasible. A complication for developing-world research reactors, however, is that facility managers often face pressure to reduce stakeholder costs — and conversion to LEU, whether for fuel or targets, carries significant financial implications.

Costs too high? Several research reactors that use highly enriched uranium as fuel face no urgency to convert to LEU — they have on hand sufficient fuel inventories for many operational cycles. But for reactors that do require fresh supplies of fuel, a twofold question presents itself: Can the reactor feasibly be converted to LEU; and can conversion be carried out in an efficient, economical way? If management does decide to convert, it must find suitable financial support to ensure that the transition to LEU is smooth, guaranteeing the facility's operational sustainability.

Converting to LEU targets for the production of medical radioisotopes presents a different set of issues. Radioisotope production is a major international industry; molybdenum 99 and more particularly its decay product technetium 99 (a metastable medical isotope) play a role in about 30 million patient applications per year. Historically, the industry has been based on irradiating HEU-bearing targets (often uranium 235 enriched to more than 90 percent). Converting to LEU targets requires that the target's uranium content be increased by a factor of two or more. This presents a technical challenge. In addition, if production of radioisotopes is to remain constant, more targets are required and larger volumes of waste are produced.

Another obstacle is that converting facilities to LEU, whether it is fuel or targets undergoing conversion, often requires a lead time of several years, during which nuclear licenses and permission to engage in medical applications must be updated. All of this implies substantial up-front costs, to be borne either by the reactor or its isotope producer, or by a major stakeholder (for example, the government). In addition, research reactors and isotope production facilities must concern themselves with loss of sales during any changeover, meaning that conversion often needs to be carried out even as existing production processes continue. This has significant implications for capacity and costs.

For research reactors in the developing world that are faced with these issues, financial options are often limited. They can seek assistance from supportive stakeholders like the government. They can try to manage with the funding that is available from commercial isotope production. Or, when it is available, they can seek assistance from developed countries — incentives. (The best results are often achieved by combining all three of these methods.) Significant technical and financial assistance from developed countries has come through, among other sources, the US Energy Department and the NNSA initiative known as the Reduced Enrichment for Research and Test Reactors Program (RERTR), as well as the Russian Research Reactor Fuel Return Program; both of these have received substantial organizational and financial support from the IAEA.

Limit too low? Often, when developed and developing countries discuss HEU minimization, the first issue on the agenda is converting reactors to low-enriched uranium. The second is timely removal and disposal of nuclear materials from facilities that no longer use these materials. To assist in reactor conversion, developed countries often provide subsidized computational evaluations of the feasibility of operating reactors using LEU and of expected increases in costs for producing isotopes after conversion. Removal and disposal of nuclear materials raise issues including the secure storage of used fissile materials until they can be suitably processed or repatriated. Significant progress has been made in recent years regarding the return of used fissile material from research reactors to the United States and Russia, but problems remain — like how to repatriate residual materials associated with fuel that did not originate in the United States or Russia. In addition, the Gap Material Program, an initiative of the US Global Threat Reduction Initiative that is intended to address high-risk materials not addressed through other programs, seems to be stagnating.

All this aside, the question posed in this Roundtable — "How might developed countries best incentivize HEU minimization programs in the emerging and developing worlds?" — begs that the term "HEU minimization" be clarified.

The entire drive for HEU minimization is related to the Nuclear Non-Proliferation Treaty, and to efforts by nearly 200 signatory nations to prevent the spread of nuclear weapons. Minimizing the use of HEU in civilian applications is a natural outgrowth of the treaty. But despite regular discussions on the issue, no universal consensus exists regarding what HEU minimization, as opposed to HEU elimination, is. Moreover, considerable skepticism surrounds the idea that all levels of HEU utilization represent a real proliferation problem.

By definition, HEU has more than 20 percent concentrated uranium 235; LEU is less than 20 percent concentrated uranium 235. I present a question here, perhaps confrontational but nonetheless deserving consideration: Why can't the cut-off for LEU be raised to something greater than 20 percent, in order to help research reactors around the developing world overcome the technological and financial challenges they face in the conversion process?