UPI reports that Japan’s plutonium stockpile tops 43 tons, up 2.4 tons from 2003. UPI got its information from a Yomiuri article and a report produced by MEXT (couldn’t find a new link, so posted a report from 2004 – in Japanese), Japan’s education and science ministry.

The increase reflected suspension of a project to burn plutonium at conventional nuclear power plants, the newspaper said.

The report noted Japan also has unreprocessed, spent nuclear fuel believed to contain more than 110 tons of plutonium.

Of the 43.1 tons of plutonium, 29.3 tons are believed to be fissionable. Experts told the newspaper it takes only several kilograms of fissionable plutonium to make a nuclear bomb.

This is a byproduct of Japan’s failed plutonium economy, which was supposed to provide the country with energy self-sufficiency by using refined plutonium to power advanced fast-breeder reactors.

Because breeder technology is flawed and expensive, the goal of using plutonium in this way won’t be realized anytime soon, and an experimental plutonium fuel, MOX, is being pushed on Japan’s struggling electric utilities. A previous Japundit post talks about it here, and, for an in-depth article about the problem, check out the Bulletin of Atomic Scientists.

So, Japan has both the plutonium and the delivery systems needed to join the nuclear club.
What’s stopping Japan from developing a nuclear arsenal?

Self-restraint and a national commitment to non-proliferation, if a May 2005 statement by Japan’s Ministry of Foreign Affairs is anything to go by. Though it’s hard to tell what Japan’s policy in regards to the development of nuclear weapons might be if the country did not exist under the American nuclear umbrella.

Still, it’s a little reassuring that a country with the means, and some might say the need, to produce a nuclear stockpile is refraining from doing so.

Then again, there’s the question of what to do with all of that plutonium. There’s the idea of sticking the stuff underground and using anthropomorphic foxes and other animals as caretakers, but there’s the problem earthquakes and so on. What to do?

And, just to make Japundit residents in Kanto and Kyushu feel better, MEXT is reporting that there have been three incidents involving the mishandling of plutonium so far this year, at research institutes in Kanagawa and Chiba, and at a fisheries school in Nagasaki.