TOKYO, Oct. 7 (UPI) -- A Japanese research team is developing a technology that would make it more difficult for countries that operate nuclear power plants to produce nuclear weapons with extracted plutonium from spent nuclear fuel. If this technology can be used practically to safeguard against the misuse of nuclear energy, Japan may help bolster nuclear non-proliferation by supplementing the provisions of the Nuclear Non-Proliferation Treaty.
Last month a symposium of atomic scientists and other experts discussed research findings and action steps at the Tokyo Institute of Technology.
"Although many people think plutonium is bad, a new time is coming where we may not have to worry that plutonium will be converted to produce nuclear weapons," said Masaki Saito, professor of the Research Laboratory for Nuclear Reactors at the institute.
Spent nuclear fuel contains 1 percent plutonium, 1 percent uranium-235, 95 percent uranium-238 and 3 percent fission products. Of the plutonium, 60 percent of plutonium-239 is the primary fissile isotope used to produce nuclear weapons, and less than 2 percent of plutonium-238 is a non-fissile, alpha-emitting isotope with a half-life -- the time needed for an element to decay by half -- of 88 years.
A research team led by Saito has found plutonium-238's ratio can be increased to enhance the proliferation resistance of plutonium by transmitting minor actinides, like neptunium-237 or americium-241, to uranium fuel for nuclear power reactors. MAs are actinide elements in spent nuclear fuel other than uranium and plutonium and are classified as high-level radioactive waste.
The team developing the technology, called protected plutonium production, has conducted irradiation experiments of MAs at the Idaho National Laboratory in the United States and has confirmed that the amount of plutonium-238 produced can be controlled by changing neptunium-237's density.
If plutonium-238's ratio can be increased from less than 2 percent to several percentage points, in 1 percent of plutonium of spent nuclear fuel, manufacturing nuclear weapons becomes technologically difficult because of high decay heat and high spontaneous fission neutron sources. But the plutonium-238 does produce nuclear energy, the same as plutonium-239, when used in a reactor.
"The experimental results were what we expected. Next, we have to figure out how to apply this technology for actual use," Saito said.
The international community -- especially the five "nuclear weapons states" of the United States, Russia, France, the United Kingdom and China -- has supported nuclear non-proliferation through the International Atomic Energy Agency's safeguard system under the NPT regime without prohibiting the peaceful use of nuclear energy.
However, the NPT's loophole was exposed when India, which refused to sign it, conducted its first nuclear test in 1974, with deuterium oxide from the United States and a research reactor from Canada that were for peaceful use, not for nuclear weapons.
Currently, 30 countries are operating a total of 439 nuclear reactors, and 13 more countries plan to build reactors. When countries participating in the Nuclear Suppliers Group -- a nuclear export control regime -- added a small amount of MAs before exporting uranium fuel, the combination of extrinsic measures, such as IAEA's safeguard system, and intrinsic measures, such as the technical difficulty or unattractiveness of the nuclear material, made nuclear proliferation less likely.
Japan, the world's third country in nuclear power generation after the United States and France, has 44 tons of plutonium and now, under the international spotlight, is expected to start full-scale operation of the Rokkasho reprocessing facilities next month. These facilities will be able to reprocess about 800 tons of spent nuclear fuel per year, roughly 80 percent of the annual amount generated by 55 power plants, and add approximately 8 tons of plutonium per year. The purpose is to boost the plutonium-related technology. A sense of crisis over energy security is behind the move.
The extracted plutonium currently is stored under tight control to protect against terrorist attacks or other threats. If newly produced plutonium is replaced with the high-ratio plutonium-238, unattractive as a material for nuclear weapons, the number of IAEA inspections could be decreased and costs reduced.
"It is important to see this as one option for nuclear non-proliferation measures," said Professor Yusuke Kuno of the Nuclear Non-proliferation Science and Technology Center of the Department of Nuclear Engineering and Management at the University of Tokyo. "When uranium is exhausted 50 years later, Asian countries will ask Japan to supply plutonium. If that plutonium has applied this technology, it will be easier to give to them."
The IAEA, which not only conducts nuclear inspections under the NPT but also supports any developing technologies regarding nuclear non-proliferation, is paying attention.
"Plutonium must not be allowed to be diverted for non-peaceful purposes. Protected plutonium production is one way to ensure that, so we are supporting this technology," said Chaitanyamoy Ganguly, section head of the IAEA's Nuclear Fuel Cycle and Materials Section.
France, which generates nearly 80 percent of its electricity through nuclear energy, is assessing whether the technology can be applied to future reactors, starting in 2012.
Officials of the U.S. Department of Energy's National Nuclear Security Administration also have shown interest in this project and plan to visit Japan in mid-October to study it in detail.
This technology also reduces high-level radioactive waste as it burns MAs, most of which have a long half-life; the half-life of neptunium-237 is 2.1 million years, and those for americium-241 and americium-243 are 432 and 7,400 years, respectively.
To be safe, high-level radioactive waste needs to be buried underground and managed for thousands of years. The international community agrees this is the best disposal method, but no country has moved into action so far. This new technology may help relieve a major headache for countries with nuclear energy.
However, some issues need to be resolved before practical use of this technology is possible. Handling of plutonium-238 is difficult because of its high decay heat, which is 300 times that of plutonium-239; extracting MAs and adding it to the uranium fuel would be costly.
"It would become meaningless if Iran or North Korea got uranium fuel by another route," Kuno pointed out. "Also, it might be hard for high-cost fuel to become the world standard."
Kuno also expressed concern about "polluting" plutonium, which he called "the treasure of mankind," by altering its structure.
Japan's energy self-sufficiency is only 4 percent, with the resource-poor country buying almost 100 percent of its crude oil overseas. "Uranium reserves will be in a tough situation within this century. When that happens, we will have no other choice but to utilize plutonium as an energy resource," Saito said.
However, Japan faces a predicament with its current plan for plutonium utilization. Despite numerous safety concerns, the country is expected to start burning mixed plutonium-uranium oxide, or MOX, fuel, imported from Britain or France, in 16 to 18 commercial reactors by 2010. This has not yet happened because of a scandal in 1999 in which British Nuclear Fuels fabricated quality assurance data for MOX fuel exported to Japan, spreading distrust of nuclear energy among Japanese citizens.
Tokyo Electric Power Co., which was to have been involved in developing the MOX fuel, also lost the confidence of the Japanese public when in 2002 it was discovered to have covered up a series of technical problems. This delivered a final blow to the use of MOX in Japan.
Initially, the key to plutonium utilization was the fast-breeder reactor, which enormously enhances the efficiency of uranium utilization, increasing the efficiency of uranium use by 60 percent.
However, the United States, Great Britain, France and Germany abandoned the plan of developing FBRs in the 1990s because of technical difficulties. Japan's fast-breeder Monju reactor in Fukui prefecture also was suspended in 1995 after a natrium leakage accident. The operation was set to resume this month but was instead postponed to February, because the natrium leakage detector was producing improper operating signals throughout the year. Present plans under the Framework for Nuclear Energy Policy are to strive for commercial use of FBRs starting from 2050.
Saito hopes to apply the new technology to existing reactors within 10 years. He says applying it toward FBRs likely would happen once they are fitted for actual use.
"I think that unless we resolve problems related to safety, treatment of high-level radioactive waste, energy sustainability and nuclear non-proliferation at the same time, the future of nuclear power will be jeopardized," he said.
