Olkiluoto geology

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Re: Olkiluoto geology

Post by Blind groper » Tue Oct 16, 2012 8:52 pm

MiM wrote:Well you try to find a way to mix it that evenly, without getting any accumulation in biota et.c. on the way. Might win you a Nobel.
I said over 1000 years. That is sufficient time for natural processes to mix it well.
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Re: Olkiluoto geology

Post by MiM » Wed Oct 17, 2012 4:50 am

Blind groper wrote:
MiM wrote:Well you try to find a way to mix it that evenly, without getting any accumulation in biota et.c. on the way. Might win you a Nobel.
I said over 1000 years. That is sufficient time for natural processes to mix it well.
.:dunno: I live here and now. I don't have 1000 years to wait for the toxins to dilute and decay enough for the environment to become benign again. Furthermore, natural processes tend to accumulate stuff as well as mix it. :dunno:
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Re: Olkiluoto geology

Post by Blind groper » Wed Oct 17, 2012 8:33 am

MiM

Possibly you misunderstand my words?

The world produces somewhere between 100 and 200 tonnes of radioisotope as part of nuclear waste each year. If we store that material under water for, say, 20 years to allow the shortest half life isotopes to decay, and then dissolve it all in strong acid, and pump it, with lots of diluting water, through a pipe into one of the oceanic currents, then the concentration in the ocean will never reach a fraction of that required to do harm.

I took an extreme case, being 1000 years of pumping 200 tonnes a year into the ocean, and showed that it would not, even not allowing for radioactive decay, reach a level that could do harm. What part of that do you not understand?
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Re: Olkiluoto geology

Post by JimC » Wed Oct 17, 2012 10:17 am

MiM wrote:Numbers math and references, please :bored:
Edit: hint: One tonne of U238 isn't really that dangerous at all, whereas one tonne of Cs137 is a whole other ballgame.
Exactly. Both isotopes of uranium are harmless, long-halflife alpha emitters, but the diverse range of fission products are intensely radioactive; they need elaborate storage for a few years until the shortest halflife species decay, then careful, long-term storage after that.

Having said that, it is certainly possible for the right engineering solutions (e.g. Synroc, an Aussie invention) and sensible storage procedures to do the job effectively...
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Re: Olkiluoto geology

Post by MiM » Wed Oct 17, 2012 11:21 am

Blind groper wrote:MiM

Possibly you misunderstand my words?

The world produces somewhere between 100 and 200 tonnes of radioisotope as part of nuclear waste each year. If we store that material under water for, say, 20 years to allow the shortest half life isotopes to decay, and then dissolve it all in strong acid, and pump it, with lots of diluting water, through a pipe into one of the oceanic currents, then the concentration in the ocean will never reach a fraction of that required to do harm.

I took an extreme case, being 1000 years of pumping 200 tonnes a year into the ocean, and showed that it would not, even not allowing for radioactive decay, reach a level that could do harm. What part of that do you not understand?
You showed nothing like that, because.
1) You don't seem to understand that talking about "tonnes of radioisotopes" doesn't make much sense
2) You suppose that even mixing in the total sea volume is possible
3) You don't take into account processes that concentrate the radionuclides, even if you could originally mix them.
source

example 1)
The total sea volume is 1e18 m^3, as you correctly state. One single ton of Cs-137 has an activity of 3e18 Bq. The current nuclear energy effect is 370 GW, and for every GW about 8 kg of Cs-137 will be produced in a year, so that makes 3 tonnes of Cs-137 globally. The half life of CS-137 is about 30 years, and if you calculate the kinetics, the result is that with constant production the amount of Cs-137 will reach a steady state at 44 times the yearly production, or about 130e18 Bq, after 400 years. Mixed into your total sea volume, that would be about 0.1 Bq/l, not very dangerous - if it stays mixed and doesn't accumulate.


example 2)
One GW reactor working one year produces about 27 tonnes of spent nuclear fuel, almost all of this is radioactive isotopes, but I agree that major parts of it (in mass), like the U-238 is fairly uninteresting for this discussion. The global energy production capacity is 370 GW, so the total production of spent nuclear fuel is about 10,000 tonnes. One ton of spent nuclear fuel will have about 1e7 GBq of activity , still after 20 years of cooling (see first graph here). So let's calculate 10,000*1e7*1e9=1e20 Bq. From one years production! Multiply by a hundred years and divide with your water volume, you get 1e22/(1e18*1000) = 10 Bq/l, which happens to be the safe allowed level for Cs-137 in drinking water during non catastrophic conditions, in eg. Canada.

But the real problem with your solution, is that you need to show that you can mix well enough, and that the stuff would not accumulate anywhere, where it could become dangerous. The problem is that many things accumulate extremely effectively in the aquatic food chain, and where you have only tens of Bq:s in the water, you can have thousands in fish. The corals, mussels and plants in those reefs where you like to dive, would probably filter that stuff into themselves like crazy.
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Re: Olkiluoto geology

Post by Blind groper » Wed Oct 17, 2012 7:09 pm

MiM

Couple of points.

Remember that I am talking 1000 years for mixing. The global oceanic circulation takes about 200 maximum. Stuff discharged into the Gulf Stream will actually move all round the globe in 200 years, mixing all the time.

Cs137 is an isotope you appear to be concerned about. Are you aware that its half life is 30 years? Over 1000 years, to all practical intents and purposes, it is all gone.

The decay over the first 20 years under water that I mentioned is shown in this graph from your reference.

Image


Meaning that most of the worst radiation is already taken care of. 95% of the radioisotopes left after 20 years are uranium and plutonium. U235 is already present dissolved in the ocean at a level of 50 million tonnes.

Life on Earth is exposed to just under 3 millisieverts per year on average, but can handle 100 millisieverts per year easily. What I am talking about, disposal at sea in predissolved form, will not expose anything to this level of radiation, because of the incredible, amazing level of dilution. Sufficient dilution will happen almost immediately, because we are talking of a small stream of dissolved radioactive material, and a hell of a lot of water.

Of course this will never happen. Not because of the spurious reasons you put up, but because of fear, paranoia, and politics.
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Re: Olkiluoto geology

Post by Blind groper » Wed Oct 17, 2012 7:23 pm

JimC wrote:
Having said that, it is certainly possible for the right engineering solutions (e.g. Synroc, an Aussie invention) and sensible storage procedures to do the job effectively...
And an opportunity for Australia to make obscene amounts of money.

Since the system I described, with disposal in dissolved form in the ocean, will never be implemented due to irrational politics, Aussis can create a very, very lucrative business. Billions of dollars in disposal fees.

What Australia has got, which is almost unique, is desert areas in geologically very stable conditions, and almost zero population. The Simpson Desert, for example, has parts that are 1000 kms from the nearest large population centre, dry as the proverbial bone, and no chance of earthquake or volcano for at least a million years. Even high level nuclear waste will decay, within 10,000 years, to a point where it is safe enough for standard land fill disposal.

Australia has a number of abandoned open cast mines in suitable locations. All it needs to do is charge a nuclear waste producer massive sums of money to place the waste, in approved containers, in the hole. Later on, the hole can be back filled with desert dirt and sand. No risk whatever to Australians, but a vast flow of money.
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Re: Olkiluoto geology

Post by MiM » Wed Oct 17, 2012 8:04 pm

If you had read and understood my example 1, or would understand anything about what you are talking about, you would not try to come patronizing me about the decay of Cs-137. :nono: The steep decline you see in the first five years are from shorter lived products, like the iodine, I am sure you heard about during the Fukushima accident. The decay of Cs-137 (and Sr-90) is what you see dominating the slow slope on the right side of the graph. Furthermore that graph is for fission products only, which means that the generally more long lived actinides (U, Pu,Am,Cu et.c) are not in there at all, but during this early period, it is the fission products that dominate the activity.

Yes, life can go on with 100 mSv/y, but the cancer rates would skyrocket. Is that really what you say? that because we will not reach this disastrous level, it's ok to just dump and dilute, even though less than a percent of that could already show up easily n the cancer statistics :shock:
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Re: Olkiluoto geology

Post by MiM » Wed Oct 17, 2012 8:14 pm

Blind groper wrote: And an opportunity for Australia to make obscene amounts of money.
And Finland could take a share of that, by selling the technique and know how we have developed for that purpose to you ;)

Spent nuclear fuel takes about 100,000byears to reach the original activity of the Uranium, that went in. This still isn't really "safe for landfill", unless you dilute it back to something close to the amount of uranium ore originally mined. Probably not a cheap process. If you reprocess the fuel, and take out the still useful materials, for further energy production (mostly U and Pu) the time for the reproessing waste to reach the same specific activity as the original uranium is about 1000 y.
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Re: Olkiluoto geology

Post by MiM » Wed Oct 17, 2012 8:25 pm

The cheapo way to dispose of the spent fuel, would be to transform it into a glassy substance (like is already done with reprocessing waste), put it into thick seawater resistant canisters, and dump the canisters in the deep sea trenches. Then, hopefully most of the waste would be buried by sediment, before it would even begin to dissolve in any significant amounts. And even if some of the fuel would be dumped in spots where sedimentation is not active, it would dissolve very slowly, and then become diluted through both time and the dilution processes you suggest.
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Re: Olkiluoto geology

Post by Blind groper » Wed Oct 17, 2012 9:05 pm

MiM wrote:
Yes, life can go on with 100 mSv/y, but the cancer rates would skyrocket.
Wrong.

The place in India I mentioned before, with over 200 millisieverts per year from hot geothermal waters, has cancer rates no higher than elsewhere. Another study, reported a while back in New Scientist, showed that the survivors of Hiroshima who received 100 millisieverts or less in a single dose, had no more cancers, and lived just as long, as people elsewhere in Japan.

MiM
I agree that many radioisotopes emit more radiation per gram than U235. However, that matters very little when dilution factors are high enough. The exposure in the ocean will still be tiny. I have seen the calculations some time back (you don't think this idea was original to me, do you?). The calculated increase was substantially less than the 3 millisieverts per year global average, but it was some time ago, and I do not have that data anymore.

The fact is simple. The dilutions I am talking of are astronomical. If a waste stream pumped 100 tonnes per year of dissolved radioisotopes (prediluted with a million tonnes of water) into the Gulf Stream, that is into a total volume of just under a trillion tonnes of water. So even before further mixing, the dilution is down to 1 part per 10,000 trillion.

Anyway, it is a pointless argument. As I said, I am fully aware that political paranoia will ensure that this solution to the problem will never be considered.
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Re: Olkiluoto geology

Post by MiM » Wed Oct 17, 2012 9:25 pm

Blind groper wrote:
MiM wrote: The fact is simple. The dilutions I am talking of are astronomical. If a waste stream pumped 50 tonnes per year of dissolved radioisotopes into the Gulf Stream, that is
I calculated the numbers for the dilution. Yes they are astronomical, but the safety factors are still rather low, something in the vicinity of 10-10000. That means you have to show that your simplistic scenario really holds, and that there will be no significant accumulation of the nuclides anywhere where it can reach humans eg through the food chain. And here I am convinced you will fail, because accumulation in the food chain is a well established process for many toxins and many radionuclides (including caesium).

Research (mostly on Japanese bomb survivors) show that cancer roughly doubles with every 1.5 Sv of exposure. That is what you will get in 15 years, if you heighten the radiation level to 100 mSv/y. I call that soaring cancer rates.
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Re: Olkiluoto geology

Post by Blind groper » Wed Oct 17, 2012 9:57 pm

MiM wrote:
Research (mostly on Japanese bomb survivors) show that cancer roughly doubles with every 1.5 Sv of exposure. That is what you will get in 15 years, if you heighten the radiation level to 100 mSv/y. I call that soaring cancer rates.
I agree that 1.5 sieverts is nasty.
But we were talking of 0.1 sievert. A different situation entirely.

The idea of cancer rate increase for small increases in radiation is known as the "no-threshold model". It is often used in calculations, especially by organisations like Greenpeace, who have political reasons for exaggerating potential problems.

Sadly for this model, there is exactly zero evidence for no threshold. There is, instead, a great deal of evidence that a threshold exists, even if the level of that threshold is hard to define. According to the New Scientist article, that threshold is probably about 100 millisieverts, if we are talking of all the exposure in one hit. If we are talking of exposure spread over 12 months, the threshold is probably quite a bit higher, but (as I said) hard to define. Government regulations, which have to be very conservative, limit radiation workers to 50 millisieverts per year.

Anyway, the end result of all this is that, if people are exposed to anything less than 100 millisieverts per year, there will probably be no increase in cancer rates.

The following chart gives a more detailed set of results for the effects of various doses.
http://xkcd.com/radiation/
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Re: Olkiluoto geology

Post by Blind groper » Wed Oct 17, 2012 10:09 pm

MiM wrote: here I am convinced you will fail, because accumulation in the food chain is a well established process for many toxins and many radionuclides (including caesium).
How much accumulation are you talking about?

I mean, if we assume occasional accumulation to increase the spot radiation levels to three orders of magnitude higher than background, it will still be safe. The concentrations we are discussing are really, really small. As I said before, there is already 50 million tonnes of weakly radioactive U235 in the ocean. Is that not accumulated also?

Bearing in mind both the immense dilution and the decay into harmless by products, such things as Cs 137 will never, ever, be able to reach harmful levels, even with bioaccumulation.
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Re: Olkiluoto geology

Post by MiM » Thu Oct 18, 2012 6:07 am

Blind groper wrote:
MiM wrote:
Research (mostly on Japanese bomb survivors) show that cancer roughly doubles with every 1.5 Sv of exposure. That is what you will get in 15 years, if you heighten the radiation level to 100 mSv/y. I call that soaring cancer rates.
I agree that 1.5 sieverts is nasty.
But we were talking of 0.1 sievert. A different situation entirely.

The idea of cancer rate increase for small increases in radiation is known as the "no-threshold model". It is often used in calculations, especially by organisations like Greenpeace, who have political reasons for exaggerating potential problems.

Sadly for this model, there is exactly zero evidence for no threshold. There is, instead, a great deal of evidence that a threshold exists, even if the level of that threshold is hard to define. According to the New Scientist article, that threshold is probably about 100 millisieverts, if we are talking of all the exposure in one hit. If we are talking of exposure spread over 12 months, the threshold is probably quite a bit higher, but (as I said) hard to define. Government regulations, which have to be very conservative, limit radiation workers to 50 millisieverts per year.

Anyway, the end result of all this is that, if people are exposed to anything less than 100 millisieverts per year, there will probably be no increase in cancer rates.

The following chart gives a more detailed set of results for the effects of various doses.
http://xkcd.com/radiation/
Sadly, there is as little evidence for a threshold as there is for no threshold. I read New Scientist too, but mostly for giggles and luls, not for rigorous scientific facts. As an anecdote, I once attended a scientific seminar with a panel debate on the threshold issue. Those who argued for no threshold used arguments from biology, epidemiology and physics, whereas those who argued for threshold used mainly arguments from economics. Simplified, their main argument was "no threshold is terribly expensive, ergo there is a threshold" :fp:.

Your suggestion here then, is to create this enormous experiment, where we expose everyone living near the coastline and eating fish to elevated radioactivity. Then 50 years from now we will see if cancer rates have gone up. An interesting way to solve the threshold/no threshold dispute, but don't you find it a little bit risky :ask:

Yes, that rad chart is a classic, and a very good one :tup:, and to be clear I agree fully that there is lots of hype about the danger of radiation, and we placidly accept much much bigger dangers in other areas (like air pollution from coal combustion). But I still don't think it's a good idea to dilute all our nuclear waste into the oceans.
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