How Japan Lost Track of 640kg of Plutonium

Lasrick sends this quote from the Bulletin of the Atomic Scientists: Most people would agree that keeping track of dangerous material is generally a good idea. So it may come as a surprise to some that the arrangements that are supposed to account for weapon-grade fissile materials—plutonium and highly enriched uranium—are sketchy at best. The most recent example involves several hundreds kilograms of plutonium that appear to have fallen through the cracks in various reporting arrangements. ... [A Japanese researcher discovered] that the public record of Japan’s plutonium holdings failed to account for about 640 kilograms of the material. The error made its way to the annual plutonium management report that Japan voluntarily submits to the International Atomic Energy Agency ... This episode may have been a simple clerical error, but it was yet another reminder of the troubling fact that we know very little about the amounts of fissile material that are circulating around the globe. The only reason the discrepancy was discovered in this case was the fact that Japan has been unusually transparent about its plutonium stocks. ... No other country does this.

Comments

Well dang, 640 kg?

[serviscope_minor]

This sounds bad: any slashdotter ought to realise, 640kg of plutonium ought to be enough for anyone.

Re:Well dang, 640 kg?

[Anonymous Coward]

1) It wasn't 640kg of plutonium. It was 640kg of fuel rods that contains a much smaller amount of plutonium
2) They were at Fukushima the whole time.
3) The "Dude, Where's My Plutonium?" spreadsheet didn't have a column for "Halfway loaded into a reactor that just got hit by a tsunami"
4) The plutonium bean counters noticed that SUM() didn't include the new column.

Come now.

[Rei]

Let's not make a big deal out of this. 640kg of reactor-grade plutonium is only enough for a bit over 100 fission bombs / fusion bomb first stages, merely enough to make the recipient roughly tied for being the world's sixth most armed nuclear power.

Nothing to see here.

Re:Come now.

[taiwanjohn]

According to another post this plutonium could not be used to make a bomb, and the explanation makes sense to me. So even if they change the constitution they won't be making any bombs, at least not with this plutonium.

Re:Come now.

[MachineShedFred]

Except that "reactor grade" plutonium is unsuitable for weapons, and cannot have the undesired isotopes of plutonium separated out of it to make it weapons grade. There's a reason why the US built the special reactors at Hanford for weapons production - you can't just make material suitable for weapons in any commercial generating station.

But besides that, yeah we should all duck and cover.

Re:Come now.

[Mr D from 63]

Except that it was never lost, and you'll find that not in the summary, but midway through TFA where it says they just entered it in the wrong column on a spreadsheet . Disaster averted. Spreadsheets are actually tools of terror!

Re:Come now.

[HybridST]

640 kg in, say, 640 1kg dirty bombs wouldn't need to be nuclear, only radioactive. Might be enough to "dirty-up" a whole lot of china's land.

Re:Come now.

[Archtech]

Exactly. "No plutonium was actually lost, and the IAEA was quick to confirm that its own safeguards, which are there to ensure that no nuclear material is diverted, were applied at all times".

More worrying is the admission that "[a]s it turned out, the Genkai plant’s internal accounting system could not properly deal with such a situation, and the material ended up in the wrong column on a spreadsheet".

Spreadsheets are probably not appropriate for such critical applications. Their deceptive simplicity and ease of use makes it far too easy to enter data wrongly, or fail to understand the hidden logic behind an apparently straightforward array of numbers. See, for example, http://www.theregister.co.uk/2.... There are plenty of other detailed indictments of spreadsheet errors (and how easy it is to make them).

Re:Come now.

[Luckyo]

Reading the TFA pretty much tells you that your "likely explanation" is the exact opposite of what actually happened.

Hint: a cleric sitting in his office somewhere filing lots of reports accidentally pasted the wrong number into the column. Woops. Clearly, a government conspiracy to create nuclear weapons from material that you can't make any from in the first place.

Re:Come now.

[MachineShedFred]

The mass difference between Pu 239 and Pu 240 is so insignificant that it is completely infeasible to use any current production isotope separation techniques (gaseous diffusion, centrifuges, etc.) and Pu 240 reacts to chemicals exactly the same as Pu 239, so you can't cheat it by using a chemical bath to dissolve the stuff you want / don't want (PUREX). There are experimental techniques, but they are so unreliable or expensive that it's cheaper and faster to just build a reactor to make the stuff if you're that serious.

We're talking about national governments here. They don't need to clandestinely take some mixed-isotope garbage from a commercial reactor and recondition it at prohibitive expense and complexity for a weapon. They can just build a short-cycle reactor or one that allows adding and removing U238 slugs while the core is running and tell the UN to fuck off - seems to have worked out just fine for Iran (allegedly), North Korea, Pakistan, and India. The process is really quite technically easy after we figured out how to do it in the 1940s, it's just a matter of spending the money and having the feedstock fuel to begin with, which Japan has shloads of.

Re:Come now.

[ultranova]

What kind of a better replacement that clerics involved in rotating those numbers en masse on continous basis are you suggesting?

A proper double-entry bookkeeping system, with every location an account. Why hack together a solution when the problem was solved centuries ago?

Re:Come now.

[blindseer]

Plutonium has a half life somewhere between thousands and millions of years. It's too stable for use as a dirty bomb. For something to be a radiological threat it would have to have a half-life on par with a human lifespan, or much shorter.

Typically a dirty bomb is used to scare or kill people off long enough that the area is abandoned but not so long that the attacker could not take over the area for their own use. Even if the attacker did not want to make use of the bombed area, and just wanted to deny it's use to anyone, something with a long half life is still undesirable. The longer the half life the more material the bomb would have to carry to irradiate a given area. With a half life of thousands of years there would have to be 100x more material than if a material with a half life of tens of years.

A more practical dirty bomb would use something like cobalt, tritium, cesium, strontium, or polonium.

Another problem with plutonium in a dirty bomb is that it's relatively inert chemically and very dense. Cleaning up plutonium would be almost trivial since it does not collect in the body, sinks like a stone in water, and only reacts with the most caustic of chemicals. Tritium would make drinking water and plant life radioactive for decades. Strontium likes to collect in the bones and irradiate people from the inside out.

Plutonium on the other hand likes to wash off, collect at the bottom of things, isn't taken up by plant or animal life readily, and has a half life so long that even if it collects in the body is unlikely to decay within a human life span.

You know, I scare myself sometimes that I know this stuff.

Misreporting

[Anonymous Coward]

From TFA: "No plutonium was actually lost, ... the material ended up in the wrong column on a spreadsheet."

That's because all Pu isn't created equal. It begins as some Pu in a used fuel element. It can be separated to become elemental Pu, which is somewhat dificult. The Japanese incorporate this into MOX fuel, from which it could easily be separated again (which would be pointless, but never mind). And then the MOX fuel is used, and the Pu (both old and new) becomes difficult to isolate again. This particular 640kg of Pu is in the form of an unused MOX core for a reactor which was scheduled to be started, but due to the hasty shutdown of all nuclear power in Japan after March 2011 never was. So the Pu in the unused core ended up in the books as a used MOX core.

Moreover, Podvig hints that this is about weapons grade material. It's not. Japan doesn't have a (working) fast breeder, no Hanford-style Pu production reactor, and no Magnox-style dual purpose reactors. This Pu is from light water reactors, therefore heavily irradiated, therefore isotopically a mess, and therefore not weapons-grade and never going to be weapons grade by any means. But Podvig makes a living off the case of nuclear non-proliferation, so of course desaster is looming, or he wouldn't have a job anymore.

Re:Misreporting

[antifoidulus]

Damnit Microsoft, when are you going to finally include a Plutonium macro in Excel!

We've heard this one before

[Chrisq]

Sellafield in the UK lost nearly 30 kg of plutonium in 2005. But that was on paper only.....except the plutonium washed out to sea. Of course it can't enter the human food chain can it?

Re:We've heard this one before

[Sockatume]

If I'm reading that right, the material wasn't lost, it just couldn't be accounted for after deliberate disposal because they made some seriously incorrect assumptions about how it would sequester itself in the environment. So that's a different issue.

huh

[Charliemopps]

Sensationalize much?

From the Summary:

How Japan Lost Track of 640kg of Plutonium

From the Article:

No plutonium was actually lost

This was an accounting error, nothing more.

Damn!

[TheDarkMaster]

Damn, they found my scheme! Now I will have to get plutonium for my diabolical plans elsewhere.