Frank von Hippel, author of a new report on highly enriched uranium, speaks at the 15 March meeting of the International Panel on Fissile Materials. | Earl Lane/AAAS
There is enough highly enriched uranium on hand to fuel non-weapon uses of the fissile material for a century, a nonproliferation specialist told a gathering at AAAS, and he urged a ban on new production for both civilian and military use.
“Why make more?” asked Princeton University physicist Frank von Hippel. He said emerging technologies make it feasible to phase out virtually all non-weapon uses of highly enriched uranium, or HEU, in the next several decades, including its use in research and naval reactors.
There are compelling reasons to end production of the material, said von Hippel, author of a new report on HEU that was unveiled at a 15 March meeting of the International Panel on Fissile Materials (IPFM), an independent group of arms control and nonproliferation experts from 17 countries. Panel members met at AAAS, with the help of the association’s Center for Science Diplomacy, to discuss key issues underlying the upcoming Nuclear Security Summit to be hosted by President Barack Obama in Washington, D.C. on 31 March and 1 April 2016.
Von Hippel cited concerns since the late 1970s about the nuclear proliferation risk associated with widespread use of HEU to fuel civilian reactors. There also is increasing concern that terrorists could make an improvised nuclear device if they were to get their hands on several tens of kilograms of HEU. The atomic bomb that destroyed Hiroshima contained about 60 kilograms (132 pounds) of the material. It was a simple, gun-type assembly in which one piece of the uranium metal was fired at another to make a supercritical mass and generate a nuclear explosion.
As the Cold War ended, Russia and the United States drastically reduced their huge nuclear-warhead stockpiles, which released stocks of HEU far in excess of their foreseeable needs. By the end of 2014, they had down-blended a combined 663 tons of the material to make low-enriched uranium (LEU) for use in power-reactor fuel. But Russia and the United States still have about 700 tons of surplus HEU remaining from their retired Cold War nuclear weapons, von Hippel says, and much of that could be devoted to non-weapon uses as they are being phased out.
“Even as current rates of use,” he writes in his report, “there remains enough HEU from excess Cold War nuclear warheads to satisfy non-weapon needs for a period on the order of a century.”
New HEU currently is being produced only by India, Pakistan, Russia, and probably North Korea, the report says. Russia’s production is for non-weapons purposes. India’s production is, at least in part, for use in nuclear submarines. Pakistan’s HEU is for weapons, as is any produced by North Korea.
By the end of 2014, the remaining global stockpile of HEU was about 1,370 metric tons of HEU, of which about 300 tons are in about 10,000 operational warheads and associated working stocks. “Since HEU can be recycled efficiently from old into new weapons, unless the weapon stockpiles grow again, little additional HEU will be needed for weapons,” the report says.
Non-weapon uses of HEU consume an estimated total of about seven tons of the material each year. Here is the breakdown, according to the report:
Fuel for naval and icebreaker propulsion reactors (4 tons): As of late 2015, there were more than 150 nuclear-powered submarines and ships that use HEU as fuel in their propulsion reactors. More than half belong to the United States: 10 aircraft carriers and 73 submarines. Russia has 42 submarines, seven research submarines, two cruisers and six icebreakers powered by HEU.
Fuel for tritium isotope production (1 ton): There are two tritium production reactors in Russia. Tritium is used to “boost” the fission chain reaction in nuclear weapons with a burst of fusion neutrons. France shut down its two HEU-fueled tritium production reactors in 2009. The United States currently gets its tritium from a single reactor that uses low-enriched uranium.
Fuel for breeder reactors (1 ton): Russia uses HEU in a prototype plutonium breeder reactor—a reactor designed to “breed” more nuclear fuel than it consumes. That reactor, the BN-600, is projected to be retired between 2020 and 2025.
Fuel for research reactors (0.7 ton): There are 99 operating research reactors that use HEU for fuel, 53 of them in Russia. About 60 of the 99 use very little HEU and do not require refueling.
Neutron “targets” for medical radioisotope production in reactors (0.04 – 0.05 ton): HEU “targets” are used in small reactors for production of medical isotopes such as molybdenum-99, which decays to technetium-99m. That isotope is widely used as a biochemical tracer for organ scans. Most of the molybdenum-99 production is concentrated in Canada, Belgium, the Netherlands, France, South Africa, and Australia.
Elimination of HEU for nuclear naval propulsion in the United States, Russia, the United Kingdom, and India will be the most difficult to accomplish, von Hippel said. France already has changed to low-enriched uranium for its nuclear submarines and nuclear aircraft carrier, and Russia is transitioning its nuclear-powered icebreakers to LEU fuel. China is believed to be using LEU in its nuclear submarines.
In 2014, the U.S. National Nuclear Security Administration’s Office of Naval Reactors suggested for the first time that it might be possible over 20 to 25 years to develop LEU fuel for United States naval propulsion reactors. “The task is challenging because the United States has moved to lifetime cores in its nuclear submarines,” von Hippel writes. “Congress has asked for a plan for the necessary research and development. If the United States moved to LEU, so could the United Kingdom with which the United States shares propulsion-reactor design information.”
Eliminating HEU for other non-weapons uses should be easier. Within the next 20 years, virtually all HEU-fueled research reactors will be converted or retired, von Hippel said. “A road away from HEU-fueled nuclear reactors and the use of HEU targets for medical isotope production is open,” he writes in his report. “It is only necessary for governments to decide to take it.”
The International Panel of Fissile Materials is calling for inclusion of non-weapons production of HEU in a long-sought treaty that would ban military production of the material. That proposed treaty, called the Fissile Material Cutoff Treaty, would bar production for weapons of both HEU and plutonium, the other main component of nuclear weapons. It was endorsed by the United Nations General Assembly in 1993 and the Geneva-based U.N. Conference on Disarmament agreed in 1995 to begin negotiations on the pact. But the formal negotiations have never been held, stalled by various objections—in recent years by Pakistan, which does not want to be locked into an inferior position relative to India.