Making Fuel Less Tempting

Research reactors have been undeniably important in the development of both military and civilian nuclear technologies. Russia's first reactor, the F-1— still in operation at the Kur-chatov Institute in Moscow— served as a prototype for the Soviet Union's initial plutonium production reactor, and was invaluable for acquiring cross-section and neutronspectrum data and for investigating the properties of prospective reactor materials.

In the early 1950s, U.S. and Soviet scientists vigorously pursued the construction of high-power research reactors capable of testing fuel elements for power reactors and naval and space propulsion systems. It also became obvious that scientists needed simple systems designed expressly for conducting basic physics experiments, producing isotopes, and training personnel. Tank-type reactors—using water as moderator, reflector, coolant, and top shielding—were favored, and they were commonly built in scientific research centers and universities, both in the United States and in the Soviet Union.

The United States also supplied research reactors to other countries under the “Atoms >> for Peace” program inaugurated in 1953 by the Eisenhower administration. The Soviet Union countered by exporting research reactors to its allies in Eastern Europe and elsewhere.

Although many of the earliest research reactors were fueled with low-enriched uranium, by the 1960s the capacity for enriching uranium had expanded. As a result, highly enriched uranium—similar or identical to the uranium used in nuclear weapons—became more available for use in research reactors.

Highly enriched uranium offered important advantages: It allowed longer times between refuelings and permitted more compact cores with high neutron fluxes. Eventually, research and test reactors became the primary users of highly enriched uranium, apart from military nuclear programs. Naval and spacepropulsion reactors, which require compact and long-lasting cores, also use highly enriched uranium.

The civilian uses of highly enriched uranium continued to grow until the early 1970s, when two events highlighted the possible dangers of distributing materials and/or technology. The massacre of Israeli athletes at the 1972 Olympics in Munich increased awareness of terrorist activities; and in 1974, using power reactor technologies acquired from abroad, India conducted a “peaceful nuclear explosion.”

This led to a particular concern with research reactors fueled with highly enriched uranium, a concern that was heightened again after the Gulf War. It was later revealed that during the conflict, Saddam Hussein had considered using the highly enriched uranium from Iraqi research reactors (supplied by France and the Soviet Union) in a last-ditch effort to attempt to manufacture a nuclear device.

The relative accessibility of research reactors, especially those located at universities and other civilian institutes, made it difficult to assure stringent security and control of fissile materials. Civilian facilities lacked the heavily armed guards, highly secure perimeter security systems, and other safeguards systems routinely employed at weapons plants.

Fixing the problem

In an effort to reduce the vulnerability of the stocks of highly enriched uranium at research facilities, the U.S. Energy Research and Development Administration, the predecessor agency to the Energy Department, launched an international physical security program that included periodic visits to facilities with U.S.-origin nuclear materials. These inspections continue today, at a rate of five to 10 a year. 1

It was also recognized, however, that the more permanent solution to research reactor security and proliferation problems would be their conversion to low-enriched fuel.

In 1978, the United States launched the Reduced Enrichment Research and Test Reactor program (RERTR). According to Energy Department officials, “the RERTR program [remains] a vital component of the administration's nonproliferation program and is a core element supporting U.S. efforts to reduce and eventually eliminate civil commerce in highly enriched uranium.” 2

The program, run by the Argonne National Laboratory near Chicago, conducts reactor analysis and works to develop higher-density fuels and their associated fuel-cycle infrastructure. Higher densities allow the fuel to be diluted to low-enriched uranium (less than 20 percent uranium 235) without increasing the physical size of the fuel elements. The original density of commonly used U.S. fuels was about 1.3 grams per cubic centimeter.

The program targets reactors with power levels of more than 1 megawatt, which have significant refueling requirements. (Low- and pulse-power reactors typically have lifetime cores.) Approximately 40 research reactors, both in the United States and abroad, either have been or are being converted to low-enriched fuel. As a result, annual U.S. exports of highly enriched uranium declined from nearly 700 kilograms a year in the mid-1970s to zero in 1993. With the single exception of the FRM-II reactor nearing completion near Munich, Germany, no research reactor fueled with highly enriched uranium has been built in the Western world since the RERTR program began. [See “Weapons Plutonium: Bavaria Bucks Ban,” March/April 2002.]

And in the Soviet Union …

The Soviet Union launched a parallel effort to reduce the level of enrichment of research reactor fuels, also in 1978. During the next 10 years, it developed higher-density “cermet” fuel (uranium oxide dispersed in aluminum) with a uranium density of 2.5 grams per cubic centimeter, and the percent of uranium 235 reduced from 90 to 36. This new fuel was loaded into both IRT- and VVR-type reactors, the most common Soviet-designed research reactors. There were no changes in core configuration, but there was some loss in neutron flux.

Highly enriched uranium allowed longer times between refuelings and permitted more compact cores and high neutron fluxes.

During the 1980s, the Soviet Union largely stopped exporting fuel enriched to 90 percent uranium 235 to Soviet-built research reactors in other countries and started supplying them with the new, 36-percent enriched fuel instead. But when funds ran out in the late 1980s, the program ground to a halt.

A cooperative program

The breakup of the Soviet Union and the difficult social and economic transition intensified research reactor security problems in the former Soviet republics—operators lacked the funds to upgrade or operate their nuclear safeguards systems. During the Russian financial meltdown in August 1998, small research facilities found themselves in particularly dire straits. Many were unable to pay for electricity to power safeguards and security systems or to support guard force operations.

The Kurchatov Institute in Moscow has seven reactors.

In response, the U.S. RERTR program considered the revitalization and strengthening of the Russian research reactor conversion effort as an important priority. During the third Gore-Chernomyrdin Commission meeting in June 1994, Energy Secretary Hazel O'Leary and Viktor Mik-hailov, then the head of the Ministry of Atomic Energy (Minatom), discussed formally extending RERTR cooperation to Russia and agreed on the need to convert approximately 20 Soviet-designed reactors, both inside and outside Russia, to low-enriched fuel. In September 1994, Energy and Minatom representatives signed a protocol of intent to reduce fuel enrichment in civilian research and test reactors. It was agreed that Argonne would manage cooperative activities by contracting with Russian institutes to perform RERTR-related studies and support the Russian effort by providing reactor analysis and fuel expertise.

Progress has been slow, however. In the early years, the effort was essentially stalled by disputes over funding arrangements and the technical preferences of the participating Russian institutes. 3

In addition, in January 1998 the United States imposed sanctions on Moscow's Research and Design Institute of Power Technologies (NIKIET) for assisting the Iranian nuclear program. NIKIET, a reactor engineering and design center, was Russia's lead organization for domestic RERTR efforts and a general manager for U.S. RERTR contracts on the Russian side. The sanctions made the center ineligible to participate in cooperative programs.

Bureaucratic disorganization in Russia continued to impede progress until about 2000, when several participating institutes in Russia received government permission to negotiate and execute RERTR contracts directly.

The U.S. RERTR program and these Russian institutes have been pursuing a two-pronged strategy, developing higher-density 19.75-percent enriched uranium fuel and demonstrating the feasibility of conversion at specific reactors.

Developing new fuel

During the program's first several years, the Russian institutes preferred to develop higher-density cermet fuels (3.85 grams per cubic centimeter), with which they had considerable fabrication and operational experience, instead of working with Argonne-developed silicide fuels (4.85 grams per cubic centimeter). In 1997, test fuel assemblies for IRT, VVR, and MR reactors were manufactured and sent for irradiation. The IRT and MR assemblies failed the test and prematurely released fission products into the coolant. The irradiation of the VVR assembly was generally successful.

With questions still remaining concerning the ability of Russian fuel fabricators to manufacture this higher-density uranium oxide fuel, in 2000 and 2001 fuel development took a new turn that may make the work on uranium-oxide fuels obsolete.

The Bochvar Institute of Inorganic Materials, a fuel research and development institute in Moscow, proposed using uranium-molybdenum alloy fuel dispersed in an aluminum matrix. (The admixture of molybdenum helps to phase-stabilize uranium, which is important for the fuel's mechanical integrity.) Experts believe that they can achieve densities of 4 to 5 grams per cubic centimeter, which would allow conversion of all Soviet-designed reactors outside of Russia and most reactors in Russia. This work is funded by the U.S. RERTR program and draws on both Russia's past classified research into uranium-molybdenum fuels and technical data from the U.S. RERTR program.

Russian fuel manufacturing facilities are not expected to have difficulty manufacturing the new fuel. Under the Bochvar proposal, the basic fuel element would be an aluminum-clad “pin.” Fuel assemblies of more complex shapes could then be produced by assembling them from these thin pins, the serial production of which would reduce cost and improve quality.

Reactor body made in St. Petersburg for Iran's power plant at Bushehr.

Reactor conversion

Only limited progress has been made in converting individual research reactors. Conversion has received little support from Russian nuclear institutes, and it is possible that some elements of the Russian nuclear establishment continue to view all nuclear operations as sensitive and are opposed to cooperation and information sharing with the United States. Russian specialists have also observed the dissatisfaction of research reactor operators in Western Europe with RERTR arrangements and the Energy Department's refusal to convert some of its own reactors to low-enriched fuel. They believe that the use of low-enriched fuel will create a financial burden as well as entail performance penalties.

Because of the opposition within Russia, a decision was made to start practical conversion work in Eastern Europe and former Soviet republics other than Russia. If the reactor operators cooperate and the new uranium-molybdenum fuel becomes available, the conversion of the VVR-CM reactor in Tashkent, Uzbekistan, will probably occur in 2005. After this conversion, considered by program officials as a pilot project, reactors in Kazakhstan, Ukraine, the Czech Republic, and Hungary will also be converted. The actual schedule will depend on many additional factors. For example, the Maria reactor in Poland, which has recently made a transition to 36-percent enriched fuel, has enough fresh fuel to meet its needs until 2009, and so is not expected to convert before then.

At the same time, the program will continue to work on the technical problems involved in converting the remaining Soviet-built research reactors. The hope is that reactor conversion experiences in Eastern Europe and the former Soviet republics will demonstrate that the new fuel has advantages, convincing Russian reactor operators to make the transition.

Incentives for reactor operators

Convincing reactor operators to convert will be a challenging task and will require focused and sustained efforts on the part of both Russia and the United States.

Reactor operators will more likely agree to make the transition if they are offered a package of incentives, including

• • a guaranteed supply of fuel for a reasonable period of time;

• • assistance in removing the existing backlog of spent fuel off-site; and

• • payment for, and disposition of, excess unirradiated highly enriched uranium fuel.

The first of these incentives would probably require the United States to pay a fuel fabricator (presumably one in Russia) for at least the first new fuel core. The United States also would cover fuel qualification and other conversion-related expenses. The second and third elements of the package would involve paying Min-atom to package and move both spent and excess fresh highly enriched uranium fuel to Russia, as well as for storing and ultimately disposing of the fuel.

As a first step in becoming eligible to receive these incentives, reactor operators would have to switch to 36-percent enriched fuel until the more advanced fuel became available. If conversion to 36-percent enriched fuel were not possible for technical or operational reasons, the RERTR program would seek a commitment that the operator would work with the RERTR program to investigate potential conversion options and to make a transition to low-enriched fuel as soon as an appropriate fuel became available.

Developing uranium-molybdenum fuels with a density of 9 grams/cc would enable the conversion of nearly all high-power research reactors.

Strengthening the program

The U.S. RERTR program is itself facing a number of challenges. In recent years it has received little attention from Energy's top managers. The level of funding is also insufficient. To date, much of the RERTR work in Russia has been paid for by a $1.5 million grant from the State Department's Nonproliferation and Disarmament Fund. A large portion of this money has already been expended, and the program may be unable to fund projects related to the conversion of Russia's higher-power research reactors.

In principle, work in Russia could be supported with Energy Department funds. But the RERTR program budget for reactor conversion and fuel development has been declining in recent years.

Meanwhile, the program is working against time to develop advanced uranium-molybdenum fuel. The current plan is to qualify fuel with densities of 6 grams per cubic centimeter by 2004. This milestone is critical because, at that time, the United States will begin curtailing its policy of taking back spent fuel from converted reactors. Argonne's silicide fuel is difficult to reprocess, and reactor operators outside the United States would have a difficult time disposing of it.

The French company Cogema has said, however, that it will be able to reprocess the new fuel, so the spent fuel management dilemma may be solved.

Developing uranium-molybdenum fuels with a density of 9 grams per cubic centimeter is the program's next expected milestone, which would enable conversion of nearly all high-power research reactors in the United States and elsewhere.

The RERTR program focuses on a fairly narrow (although important) class of targets—steady-power research reactors that consume highly enriched uranium continuously. It leaves untouched other important stocks of highly enriched uranium fuels, including those in pulse-power reactors, naval propulsion reactors for submarines and icebreakers, and Russian tritium production reactors. With adequate funding and strong political support, RERTR-developed capabilities could be used to phase out the use of highly enriched uranium at many of these facilities and associated critical and subcritical assemblies.

The United States and Russia each consider the design of submarine propulsion and some other reactors as classified. Although no collaboration on these reactors is possible at present, even they could eventually be transitioned to low-enriched fuels.

The RERTR program can serve a critical role in reducing the nonpro-liferation and security threat associated with highly enriched uranium-fueled research reactors in Russia and other countries. Significant progress has already been made in developing low-enriched fuels. But the cooperative effort continues to face technical and political problems, and the projected timeline for conversion to low-enriched fuel is a long one.

In the United States, the RERTR program has a very low profile and its annual funding is minute—even when compared to other cooperative nuclear security programs. But it is an important program that clearly requires a much higher priority, both in the United States and in Russia. With adequate funding, political support, and coordination with other U.S. nuclear threat reduction efforts, the RERTR program could become an effective tool in eliminating vulnerable stockpiles of highly enriched uranium in the former Soviet Union and elsewhere. •

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