Posted on 01/28/2003 2:13:20 PM PST by MadIvan
Japan on Tuesday admitted that 206kg of its plutonium - enough to make about 25 nuclear bombs - is unaccounted for.
Government scientists said that 6,890kg of plutonium had been extracted since 1977 from spent nuclear fuel at a processing plant about 120km north east of Tokyo. But that is 3 per cent short of the amount the plant was estimated to have produced.
About 5kg to 8kg of plutonium are needed to make a 20-kiloton atomic bomb similar to the one that destroyed Nagasaki in 1945.
Experts said the missing amount was surprisingly large.
There is normally a margin of error of 1 per cent or less when measuring liquid plutonium, which can dissolve into other elements.
Japan's admission comes at a time of acute sensitivity because of the threat of nuclear proliferation in north-east Asia following North Korea's revival of its mothballed nuclear programme.
However, there is no evidence that North Korea was linked to the missing plutonium even though it is known to smuggle goods in and out of Japan.
"This is an unusually large amount of plutonium to be unaccounted for, which makes me uncomfortable, although I think it's highly unlikely that it was stolen," said Tatsujiro Suzuki, senior research scientist at the Central Research Institute of Electric Power Industry.
The science ministry, which reported the discrepancy to the International Atomic Energy Agency (IAEA), dismissed the idea that the plutonium had been stolen. It said about 90kg was probably diluted into waste-water and about 30kg probably dissolved into other elements.
It admitted it was baffled by the remaining 86kg but said initial output projections may have been too high and the plutonium may not have been produced.
Mohamed ElBaradei, director general of the IAEA, said: "The Agency [is] confident that no nuclear material has been diverted from the facility."
The IAEA, the United Nations nuclear watchdog, has urged Japan to strengthen its procedures for measuring nuclear material since it first noted discrepancies in 1998.
If you operate emissions-free nuclear reactors, you make plutonium. In fact, a substantial portion of the heat in such a reactor comes from uranium-238 atoms transmuted into plutonium and then subsequently split.
My dog ate it???
Does he glow in the bark?
Uranium is 99.3% U238 and 0.7% U235. Pure Uranium is converted to UF6 where it can be enriched via gaseous diffusion (or ?) - and for reactor fuel - an enrichment of 3% to 5% is desired.
Assume a typical fuel bundle is about 1000 lbs - mostly Uranium - in an "Oxide" form - UO2 ... and zirconium filler and zirconium clad tubing. After about 3 years, the bundle is considered "depleted" and discharged permanently. (The reactor might have about 210 bundles ... so 70 bundles per year are discharged on a rotational basis.)
During operation in the reactor, assume about 50% of the Uranium is fissioned ... the rest is still useful, if you could reclaim it. But some of the U238 in the fuel absorbs a neutron and changes to Plutonium Pu239. Assume about 2% of the bundle is useful Plutonium when the bundle is discharged. 2% - 20 lbs. (10 kg). Now the actual details are more involved. The created Plutonium is also partially consumed during the reactor operations - and extends the "life" of the fuel bundle. And some of the Pu239 isn't burned but is converted to Pu240 (not good for bomb material) ... so "long-burn" fuel is less desirable for making weapons-grade Pu than fuel that spends less time in the reactor.
Both Japan and France recycle their fuel. They reclaim zirconium, reclaim Pu and U .... and the nasty fission products - less than 40 lbs per fuel bundle (4%) - is vitrified in glass for permanent isolation/burial. Even the U.S. was looking at this option . . . recycling the Pu back into reactor fuel ensures that there is no Pu "floating" around for a future theft for making bombs.
But breeders are designed to generate MORE fuel than is consumed .... and some concepts include mixing Thorium with the enriched Uranium fuel. You still get some Plutonium - but the Thorium "breeds" to U233 - which is also is hard to separate from U238 ....
So much wonderful technology is available ... unfortunately, the decisions on how to use it are often left to un-education idiots (like Jimmy Carter) - when they choose to make decisions based on politics rather than science.
Mike
Although i do remember an article where it said Japan can have nukes ready in less than a year, possibly faster. Hence it is possible that ol' Nippon has seen it is threatened by the NKs and taken its protection into its own hands. And if NK can make a bomb Japan can make one that is much better and more efficient, and then duplicate that process ad infinitum.
I have a feeling that it's a black "interagency transfer."
And how, exactly, do we know that the estimates were any good? By checking them against actual production perhaps?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.