Published on Jun 8, 2014
PROVIDED BY CNNNEXT.COM
The unused plutonium was neither revealed in the country's 20-12 nor 20-13 reports to the I-A-E-A.
It was blended with uranium into a mixture known as MOX, a mixed oxide fuel, that could be used in reactors.
The missing plutonium was found in an offline reactor in the southern town of Genkai, only after it was uncovered by a nuclear website.
It was loaded into the reactor in March 2011, and taken out two years later.
Japan's Atomic Energy Commission has argued that the plutonium is still considered being used and hence exempt from reporting to the I-A-E-A.
Nearly all of Japan's nuclear reactors remain idle since the 20-11 disaster at the Fukushima power plant.
