OT More nuclear waste problems.

[Tim Streater]

Yes. They produce a few hundred watts, typically. As Pu-238 has a half-life of 90 years or so, useful when you consider that some deep-space probes have been going for 40 years or so.

[Brian Gaff]

No but there is a heck of a lot of waste about. Brian

[Brian Gaff]

Many spacecraft have plutonium generators on board including both Voyagers, the two Vikings, the New Horizons probe and Casini, so there is no issue here. as has been said, the power requrirement of spacecraft is quite low, but there is a heck of a lot of waste about. One might be able to actually boost the output by using some form of reactant to make the material give up radiation faster. Brian

[Nightjar]

It is critical, if you are trying to put this sort of incident forward as an argument against nuclear power.

[The Natural Philosopher]

No Brian, there isn't.

There's an apocryphal story about that. If all your energy needs were supplied by nuclear energy, the resultant radioactive waste of a lifetimes nuclear power to run you and the society you need to survive, would be the size of a golf ball, and could safely be buried with you in a lead lined coffin.

What her is a lot of is low level waste which is almost completely harmless and consists of a very very very little bit of high level radioactive crap in a huge quantity of completely on radioactive crap that is simply not worth separating it from.

High level waste, waste that actually produces enough radiation to even get warm, Or represents any danger to life, is very very small.

For example, all the nuclear power stations in the U? plus a few more from overseas that sent stuff for reprocessing have extracted no more than IIRC 110 tonnes of plutonium in the entire history of nuclear power.

(plutonium is of course not the most toxic material ever created. Thats probably ricin).

That is stockpiled at Sellafield waiting for the price of Uranium to rise enough so that it has commercial value as fuel.

Do you know how BIG that is? plutonium is around 20 tonnes per cubic meter, so that's only 5 1/2 cubic meters.

Which you could fit in the back of a single Ford Transit.

I cant remember the exact t figures, but in a breeder reactor that is enough to meet the entire UKs electricity generation needs for 10 years or something.

Outside of a reactor its pretty much useless. Plutonium is pretty stable and decays only slowly, so it safe to handle and last a long time. Perfect for bombs or power stations, useless for power generation at high levels outside of a critical mass reactor.

Other waste products are even smaller.

You see the problem is, as with Saddams WMD, that in order to be scary, you have to put things together that don't belong together. Saddam had missiles capable of reaching Israel, and probably Malta. He had had artillery capable of being ready to fire chemical shells in 45 minutes. What he didn't have were 45 minute ready weapons that could also reach Malta or Israel, and threaten British interests. And in fact he didn't have any more chemical shells either, as Dr Kelly tried to say before he conveniently 'killed himself'.

In the case of waste, its highly radioactive waste, and bulky long lived waste.

In reality the bulky long lived waste is not highly radioactive. To be radioactive implies radioactive decay, and if that is slow there's not a lot of radiation inbvolved.

such high level waste as there is is either very very radioactive - like Iodine 131 - so its gone very quickly or it tends to be much less radioactive like plutonium, which means its a suitable reactor fuel.

The worst headache is the in between stuff. Half lives in the year to a thousand hear range.

Dangerous enough to need a bit of care, but hangs around a long time. Especially if the body absorbs it.

Like strontium 90 and caesium 137. Both of which were showered on the world by atomic tests in the 50s

To as far as we can tell, no detrimental effects at the levels they were released at.

Strontium 90 is a decent power source for satellites and the Russians used it .

half life is < 30 years though so you simply have to keep it around 300 years and there's bugger all left.

Caesium 137 is very similar: 30 years half life. Its the main isotope of concern at Fukushima where work to reduce its effect to less than one tenth of the natural background radiation of e.g. Dartmoor progresses.

Of course Dartmoor, actually linked with a just measurable increase of cancer from natural RADON gas, is not restricted access even to Japanese tourists.

Unlike the Fukushima exclusion zone, which is by and large far less radioactive.

But all of this pales into insignificance besides e.g. naturally occurring potassium-40 (40K)

"40K occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. In healthy animals and people, 40K represents the largest source of radioactivity, greater even than 14C. In a human body of 70 kg mass, about 4,400 nuclei of 40K decay per second"

Potassium 40 has a half life of 1.2 billion years

Do you now realise what the largest source of long lived radioactive waste is, Brian?

You are.

And lay off the bananas.

[Jethro_uk]

The rate of radioactive decay is unaffected by chemical (and physical) processes. One thing I do remember from studying it ....

[dennis]

You mean put it in a reactor and use it as fuel, what a novel idea.

You can't use chemical reactants to make any difference as the decay happens in the nucleus.