“This sort of plutonium fuel is more difficult to control than uranium fuel,” said Arjun Makhijani, a nuclear scientist and the president of the Institute for Energy and Environmental Research.
The fuel, known generically as MOX, was made by nuclear giant AREVA in France, where MOX technology has been used for almost two decades.
The rods, made by blending small amounts of plutonium with traditional uranium, were loaded into Unit 3 of the Fukushima Dai - ichi nuclear plant last September.
Makhijani said the unit contains 32 MOX assemblies , about 5 percent of the fuel now in the reactor, where an explosion this week kindled fears of a radiation release.
“With this fuel, the risks of accidental criticality are different,” Makhijani said. “You have the same kinds of problems ; they are just more intense with plutonium.”
AREVA is also part of Shaw AREVA MOX Services – the group building the National Nuclear Security Administration’s $4.86 billion MOX plant at Savannah River Site.
The MOX fuels used in the Japanese reactor and several dozen others are a mixture of uranium and plutonium reprocessed from spent uranium, but the facility at SRS is designed to use weapons - grade plutonium from dismantled nuclear warheads to make fuels
usable in commercial nuclear reactors.
The plant’s mission is to dispose of the weapons - grade material to prevent exploitation by terrorists. T he search for utilities willing to use the fuel when production starts in 2018 has moved slowly.
Currently, the Tennessee Valley Authority is evaluating the use of MOX fuel in as many as five of its reactors, and a Richland, Wash., utility is mulling
its use in one unit, but no formal user agreements have been signed.
Safety officials have pointed out that the problems in Japan were caused by the combined effects of the earthquake and tsunami – not by the type of fuel in the reactors.
In an e-mailed statement Tuesday, a National Nuclear Security Administration spokesman said U.S. officials remain confident about the safety of existing programs.
“The American people should have full confidence that the U.S. has rigorous safety regulations in place to ensure that our nuclear power is generated safely and responsibly,” the spokesman said. “Information is still coming in about the events unfolding in Japan, but the administration is committed to learning from Japan’s experience as we work to continue to strengthen America’s nuclear industry.”