James ActonWhat to do with British Pu?

Here’s an interesting factoid. The UK and US each possess about 100 MT of separated plutonium. However, the UK stockpile is largely civilian, whereas the US stockpile is almost entirely military.

The UK is currently engaged in a debate about what to do with this plutonium. Last year the Royal Society published a report on the subject and last week the Nuclear Decommissioning Authority (the UK public body charged with cleaning up Britain’s messy nuclear legacy) published draft options for public comment.

The NDA report spells out the options, which broadly fall into three categories: “store indefinitely”, “immobilise and dispose” and “reuse and dispose”. It runs through the pros and cons of each option and, frankly, there’s not much point me recounting the argument here—it would take about as long as the report itself.

One conclusion that is worth highlighting, however, because it is potentially particularly controversial concerns immobilization with high level waste:

To achieve this method of plutonium disposition in the UK would require retaining high level waste liquors at Sellafield for the length of the plutonium immobilization programme, which would be around 20 years once the new plant had been built and commissioned. In practice this would mean delaying the vitrification of some of the High Level Liquid Waste currently stored at Sellafield. Given that this is the highest hazard material at Sellafield, and that this strategy would delay completion of hazard reduction of the High Active Liquid Waste until all the plutonium had been immobilised, in 40-50 years, the NDA is minded to dismiss this as a credible option. However, some commentators believe this option offers potentially very high proliferation resistance. In reality, the activity of the high level waste glass drops off sharply after 200-300 years and the waste form will offer no higher proliferation resistance than any of the above candidate wastes.

What I would say is that the NDA report makes it clear quite how tricky a problem this is. For instance, one “easy” option (if you ignore the political and security problems) might be to sell UK plutonium to another state that wants it for MOX fabrication. However, I didn’t realized that

Thorp [the UK reprocessing plant for LWR fuel] derived plutonium does not currently have the capability to be exported as there are no transport container licenses for Thorp plutonium cans.

Moreover, the nature of the problem is very sensitive to the time taken to implement a solution. LWR fuel has a relatively high proportion of Pu-241 which (with a half life of 14.4 years) decays into Am-241. This may be useful in smoke detectors but it is a pain in MOX fuel fabrication (being a strong gamma emitter). Therefore, the feasibility of certain MOX fuel fabrication schemes depends on how quickly they can be implemented (bear in mind that the recent history of the UK’s nuclear programme is full of delays that are best measured on a geological timescale).

Of course, it’s always possible to design new containers or remove the Am-241 chemically. My point is that these problems make determining the “best” solution a nightmare.

Anyway, the NDA is seeking public comments, if you’re interested.

Finally, it would be remiss of me writing on this subject not to mention the International Panel on Fissile Materials. Their 2007 annual report has an excellent chapter detailing the woes of the US programme to deal with separated plutonium and I notice that Martin Forwood has recently published a paper with them on the UK mess. I haven’t read it yet but look forward to doing so.

Comments

  1. Lao Tao Ren (History)

    Can’t they wholesale it to Harrods, and have it sold in little jars to tourists?

    Just imagine the demand if there is a “clean exemption” and agreements that allow the co-mingling of civilian and military Pu, and no problems with testing!

    The whole inventory will be cleaned out in a week!

    Even better, how about selling it as a package deal with 100 Typhoons? A prize in every box! At least 1MT of Pu included with every Eurofighter!

  2. Hairs (History)

    I can’t see a pressing need for ANY decision to be made. The stuff has been accumulating for many decades now and is probably as secure as any material can be short of the collapse of civil society or an invasion by hostile forces. Therefore to do something now just for the sake of DOING something seems daft.

    It may well be that in 10 – 30 years’ time we’ll need the stuff for nuclear power generation (for example if the current sources of uranium have become prohibitively expensive). True, Pu 241 is a pain, as is the spontaneous fission rate of Pu 240, but as James points out, Am 241 could be removed chemically and it is perfectly plausible that within the given 30 years even Pu 240 could be economically removed using some advanced AVLIS process. The same is true for the other nasties that have come out of solution with the plutonium.

    I believe the best option is one that has not even been considered by the NDA, namely: “Store until it becomes economical to either burn or transmute to non-fissle / inert elements.”

    At the moment economical transmutation is a pipe dream, but we forget that 100 years ago fission had not even been demonstrated, anti-matter not even postulated, muons not discovered, and quarks were no more than a line in a Joyce poem. Given the history of technological development over the last 5,000 years it is laughable that we will remain flummoxed by this stuff for the next hundred centuries. Far more likely is that within 150 years, which is shorter even than the timespan the NDA considers with regard to residual activity of vitrified HLW, we could have tunable proton and neutron beams, atomic-scale mass manipulation technologies, muon catalysed atom-atom interactions, and, for all I know, the ability to change moles and moles of nuclei at sub-MeV energies (thereby avoiding the need for enormous accelerators) just by playing around with quantum tunnelling.

    Yes, I know my hair looks wild and unkempt, and my hands are waving fast enough to send 60 wpm in semaphore, but remember the Arthur C Clarke quote: “Any sufficiently advanced technology is indistinguishable from magic.” Problems that defeated whole nations just a handful of generations ago (e.g. reliably finding longitude) can now be solved by children (e.g. by my 6 year old nephew with the GPS that came as a cheap add-in on my cellphone).

    We can debate all day the moral issues of creating problems for future generations to deal with, but now that the problem (i.e. separated toxic, fissile material) is here, the best thing we can do is stop making the situation worse with our clumsy, meddling “somebody must DO something” attitude. Instead we should keep it out of the wider environment; lock it away from terrorists; dissuade our own governments from using it in their beloved weapons; and simply wait for the development of some grown-up technologies to burn it or transmute it.

  3. AWR (History)

    A question for those (most) of you with technical expertise: why can’t this material go into the blenddown project in Lynchburg? Or why can’t it make a shorter trip to France? Considerable political considerations aside, is there a technical reason this couldn’t happen? It seems to me this could provide some much-needed impetus to disarmament and the FMTC.

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