Enough highly enriched U.S. uranium to make about 20 nuclear weapons was sneaked back to the United States from Japan over a 12-year period until last summer in a secret operation aimed at keeping it out of terrorists’ hands, a senior U.S. official and Japanese specialists recently revealed.
The uranium, which was provided to Japan by the United States to build five nuclear nuclear research reactors, totaled more than 500 kg.
Details of the special repatriation operations, initiated by the U.S. National Nuclear Security Administration, a special wing of the Energy Department, have been kept under wraps for more than a decade for security reasons. The shipments began in 1996.
The unique nonproliferation project, called the Global Threat Reduction Initiative, resulted in a total of 579.7 kg of HEU (highly enriched uranium) being returned securely to U.S. nuclear facilities, said Andrew Bieniawski, NNSA assistant deputy administrator for global threat reduction and director of the GTRI program.
“Japanese research reactors have been very successful in shipping their spent HEU fuel to the United States,” Bieniawski said. “These shipments contribute to HEU minimization efforts worldwide and provide the reactors with a disposal path for their spent fuel.”
Since the mid-1990s, U.S. administrations have accelerated nuclear nonproliferation activities worldwide in order to prevent nuclear terrorism.
Four of the five reactors are in Ibaraki Prefecture and managed by the Japan Atomic Energy Agency. Two of its HEU-fueled reactors have already been closed due to proliferation concerns, and the other two were converted to use less-enriched uranium.
The density of Uranium 235 — and isotope key to chain reactions — in LEU is less than 20 percent, whereas weapons-grade HEU needs to be more than 90 percent pure. The JAEA was using 90 to 93 percent HEU fuel from the early 1960s to the mid-1990s, according to documents provided to Kyodo News.
The JAEA has sent 523 kg of spent HEU to the United States.
“The JAEA is an example for the world to follow. The JAEA has done 95 percent (of the entire repatriation),” Bieniawski said.
Takeshi Inoue, general manager of the Nuclear Material Management Office of the Nuclear Nonproliferation Science & Technology Center at the JAEA, said the JAEA plans to send over the remaining 5 percent in the next five years.
The other research reactor is in a suburb of Osaka and operated by Kyoto University’s Research Reactor Institute. The reactor, called KUR, started up in 1964 and used 93 percent-density HEU as fuel until it suspended operation in February 2006.
The institute is one of Asia’s major nuclear training centers and accepts more than 3,000 researchers, including foreign students, each year.
KUR suspended its operations to remove HEU fuel and repatriate it to the U.S. Kyoto University had returned about 50 kg of HEU by the end of summer.
KUR will be converted to a LEU-fueled reactor by summer 2009, said Hironobu Unesaki, associate professor and director of the Office of Nuclear Material Management at the institute, who is a key contact with the NNSA for HEU repatriation and conversion operations.
The reactors were constructed in the 1960s in the context of “Atoms for Peace,” the U.S. Cold War project advocated by President Dwight Eisenhower, which exported several dozen research reactors, HEU fuel and related technologies to allies including Japan, South Korea and South Vietnam. The Soviet Union rivaled this U.S. project and exported research reactors to its own satellite states.
Since the end of the Cold War, the U.S. has become increasingly concerned about the exported reactors and the HEU, which could be used to develop nuclear weapons. In February 2005, President George W. Bush and then Russian President Vladimir Putin agreed on a plan calling for upgrading the security at Russian nuclear facilities and accelerating efforts to return the HEU the two former Cold War rivals distributed to research reactors around the world.
Since then, the GTRI has ramped up the project and promoted worldwide operations with its Russian counterparts to secure “loose nukes” — the seeds of nuclear terrorism and other proliferation concerns.
The JAEA and Kyoto University have taken collaborative steps with the NNSA and paid expenses for shipping, storing and handling the HEU repatriated to the U.S., even though the Japanese government made no financial or manpower contribution to past or ongoing operations.
“The Japanese government hasn’t taken any financial or human support for the HEU repatriation operations,” said one official of the Nuclear Power Regulation Office at the Education, Culture, Sports, Science and Technology Ministry.