[Leica] Radioactive waste - out of sight, out of mind

[abridge at gmail.com (Adam Bridge)]

Douglas I think you have it backwards.

U-238 is the more common isotope of Uranium. Fuel is "enriched" to
increase the amount of U-235 in the fuel itself. I think the common
enrichment for commercial power reactors is on the order of 3%. Naval
reactors are enriched to almost pure U-235.

It's interesting to note that "natural reactors" have been found in
Africa. In these reactors cracks have formed that allow ground water
to penetrate into the beds of uranium.

Nuclear fission of U-235 requires neutrons that are in thermal
equalibrium with their surrounds (at anything like normal
temperatures) but neutrons that are born from fission are "fast" very
high energy neutrons. They have to give up their kinetic energy in
order to slow down so they have a much greater chance of being
absorbed into the U235 nucleas and thus cause fission.

In Africa ground water seeped down into the ore beds and provided the
"moderator" to slow down the neutrons - which caused fission and a
natural self-sustaining nuclear reaction  began.

They know this occured because first the U235 in the ore is depleted
but also because the signature traces of fission products (which are
only produced from fission, not being big in nature) are in the right
proportions. This lets them date the time of the "reactor's"
operation.

I've never seen a report on just how much power was generated or what
the radiation effect above the ore might have been. I'll have to look
for that.

I'm much more interested in seeing if there's a way to put nuclear
waste into deep subduction zones to have it sucked down between the
plates and into the mantle where geologic time comes to our aid.
Engineering problems are, of course, severe due to the pressure and
the joyous corrosive nature of sea water.

Adam Bridge


On 2/3/06, Douglas Sharp <douglas.sharp@gmx.de> wrote:
> Sorry Raimo,
> I should have written "for its volume", that's why it's called enriched
> uranium.i.e. more radiation in a small space. As a comparison, a chunk
> of haematite iron ore is not strongly magnetic, but processed into iron
> or steel the magnetism can be significantly stronger (in effect also a
> form of radiation).
> As to the usability of radioactive substances, you have to consider the
> radiating isotopes U-235 and U-238, the former is common, the
> concentration of the latter is the result of the enrichment process
> which makes uranium suitable as a nuclear fuel. The common ores, such as
> pitchblende, are relatively harmless before processing.
>  On a geological time scale caverns are a very dodgy business, as are
> salt domes. What may appear impervious at first sight just isn't - think
> about it - why are most caves and tunnels damp? Why do engineers
> tunneling through the raw mountain rock of the Alps have such massive
> problems with water, liquified clay slurries (a by-product of eroded
> granites), sand slips and structural failure of bed-rock under pressure?
>
> Geology is in a state of constant movement, not usually at a scale at
> which we can actually watch it, but let's say a few cm or inches a year
> - up down and sideways, this mounts up to a fair amount when you
> consider the half-life of radioactive waste - the time it takes for half
> of the radioactivity to dissipate - after these tens of thousands of
> years the stuff is only half as radiactive as it was in the first place.
> Particularly in the case of dense igneous rocks there is a high degree
> of tension caused by movements which is often revealed in earthquakes -
> when the tension or pressure is released all at once, this may be along
> fault lines, above magma bodies or plumes, or just a matter of two
> continental plates, which usually slide sedately over or under each
> other (subduction), at a rate of inches per year at shelf boundaries,
> which tend to get stuck to each other and then rip apart when the pent
> up force is too much.
> In your country, the Fenno-Scandian Shield is one of the slower moving
> parts of plate-tectonics, but it does move all the same - that's why
> there are so many sharp edged mountains and deep Fjords in Scandinavia.
> Although the Belgian solution seems, at first sight, to be rather
> adventurous, a relatively thin clay layer (Boom-clay in this case) is
> less pervious to gases and liquids, and more flexible in accomodating
> movement than are granites, basalts or rock salt. Radiation is worse
> than liquids and gases, it will penetrate just about anything and leave
> a path of destruction in its wake.
> Nuclear waste disposal is a matter of thinking "out of sight, out of
> mind" maybe our great-great squared grandchildren will be the ones
> having problems with it.
> None of us should ever stop worrying about this slowly ticking time-bomb.
> Hope this clarifies it a bit
> cheers
> Douglas
>
> Raimo K wrote:
>
> > How can used stuff have more radiation than unused? If it had, it
> > would be usable.
> > OK, it is concentrated into granules but if you store it deep in
> > stable rock caves (like we plan to do in Finland) and take into
> > account the immense mass of stone around the storage I see no way it
> > can have increased radiation compared with hot uranium mines.
> > All the best!
> > Raimo K
> > Personal photography homepage at:
> > http://www.uusikaupunki.fi/~raikorho
> >
> >
> > ----- Original Message ----- From: "Douglas Sharp" <douglas.sharp@gmx.de>
> > To: "Leica Users Group" <lug@leica-users.org>
> > Sent: Thursday, February 02, 2006 12:51 AM
> > Subject: Re: [Leica] RE: LUG Digest, Vol 31, Issue 221
> >
> >
> >> Hello Frank,
> >> the refined stuff has a much higher radiation output than the ores -
> >> think of tiny granules of uranium mixed in with great chunks of rock
> >> which, at least partially stop the radiation, and, btw, make uranium
> >> mines so hot.
> >> There is one method of sealing nuclear waste which is effective as
> >> far as it goes, sealing it in glass with a large proportion of lead
> >> (which doesn't shield from radiation, it absorbs it and changes over
> >> time) this has again the inherent problem of heat, the energy has to
> >> come out somewhere. Before somebody suggests dropping it into
> >> volcanos, the molten lava is much too close to the surface, getting
> >> sprayed with molten rock is bad enough, but making it radioactive too
> >> is a bit much.
> >>
> >> As to the plastics, there are some fascinating developments on the
> >> way with high quality plastics made from potato starches and waste
> >> straw from maize crops, then there's always multitudes of natural
> >> vegetable oils which haven't really been tested for making the
> >> polymers we need for plastics.
> >> The power of biological products can be seen in the recipe for casein
> >> glue - just mix curds and chalk - one of the best and oldest glues
> >> there is.
> >> The energy business  is going to become one of the main areas for the
> >> development of genetically modified plant strains, the other area is
> >> the creation of  bacteria which can reduce waste plastics to their
> >> original source materials - but that is a pandora's box I don't care
> >> to think about -  just let a bacterium like that get out of hand or
> >> mutated and start chewing up plastics just where it shouldn't, I
> >> shudder at the thought.
> >> It's interesting that most of the large oil companies are working
> >> very hard in this direction, particularly Shell and BP, they want to
> >> have the market cornered when the time is ripe. There was a research
> >> project for loosening up heavy oil deposits in a reservoir by
> >> dropping anaerobic bacteria down through the borehole, but I left the
> >> business before hearing more about it.
> >> The last stuff I was working on was the localisation of deep seated
> >> magma bodies for geothermal energy production in Tuscany
> >> (Larderello,where they've been doing it since the early 1920s) my
> >> theory for variations in their heat production was that these bodies
> >> are also subject to tidal forces caused by the position of the moon
> >> pulling them closer to the surface, unfortunately I never did hear
> >> what came of that either. At least there was a significant increase
> >> in microseismicity (tiny earth tremors) at full moon, which seems to
> >> support my theory.
> >> To get back on track, the visit to ENEL GreenPower in Pisa was a
> >> wonderful opportunity to wander around that beautiful city with a
> >> camera.
> >> cheers
> >> Douglas
> >>
> >> Frank Dernie wrote:
> >>
> >>> Douglas,
> >>> I have always wanted to ask a specialist this question, and it looks
> >>> like you may just be the person.........
> >>> What is wrong with burying nuclear waste in the exhausted mines from
> >>> which it originated? Presumably it won't be any more dangerous there
> >>> than the raw nuclear material originally mined????
> >>> The biggest concern I have re oil is not its use as a fuel, that
> >>> seems a terrible waste to me, but as the raw material for
> >>> manufacturing materials such as plastics for which we have no
> >>> reasonable alternative.
> >>> Frank
> >>>
> >>> On 1 Feb, 2006, at 19:30, Douglas Sharp wrote:
> >>>
> >>>> The technologiy is clean enough, and close to being as safe as it
> >>>> can be - the problem is still nuclear waste. As a production and
> >>>> exploration geophysicist I've worked on nuclear waste storage
> >>>> sites, working and prospective, in Germany, Belgium, Switzerland
> >>>> and a few other places. For the long-term storage of nuclear waste
> >>>> there is NO really safe solution, that stuff stays highly
> >>>> radioactive on a geological time scale.
> >>>> Salt dome caverns  are no good - salt moves and migrates so you've
> >>>> never got a constant thickness shielding your waste, the Swiss
> >>>> solution of putting it in caverns blasted out of native impervious
> >>>> (supposedly) rocks is better but radiactive gases (Radon for
> >>>> example) always manage to find a way to the surface. The Belgian
> >>>> method of hiding it under a thin layer of impervious clay isn't a
> >>>> long term solution either.
> >>>> So what do we do with it?  Shooting it into the sun is the only
> >>>> real way of getting rid of it, there's been enough dropped into
> >>>> the  sea and more than enough buried already, these "fly-dumps"
> >>>> will  take their revenge on the environment one of theses days.
> >>>> You say that  present day technologies are safe, I agree - problem
> >>>> is, even the most recent reactors just haven't been built with
> >>>> these new technologies, Temsvar in the Czech Republic is one of
> >>>> the  newest NPSs
> >>>> and is just not safe, the same applies to the latest French
> >>>> reactors, Germany's reactors have been plagued with problems and
> >>>> Sellafield in the UK is a dirty word already. No need to mention
> >>>> reactors in the former soviet block countries.......
> >>>>
> >>>> Fusion power is pie-in-the-sky (unless the billions for defence are
> >>>> re-channeled), you might just as well try a further development of
> >>>> Nikolaus Tesla's idea by building orbiting spaceborne solar power
> >>>> stations transmitting power as high energy microwave frequencies
> >>>> back to earth, though I dread to think what would happen if a
> >>>> plane  flew through one of those tight banded transmissions.
> >>>> The only clean options are  terrestrial solar energy farms, wind
> >>>> and tidal energy and geothermal energy - these are the only future
> >>>> I can see in power production.
> >>>>
> >>>> Some of the latest developments reek of science fiction but could
> >>>> be effective - half mile high chimneys set up in desert regions,
> >>>> the temperature differential between ground level and the top
> >>>> creates winds of incredible velocities, all you have to do is put
> >>>> aturbine in the way of it. Using waste energy (off peak production
> >>>> is always too high and just gets wasted) from conventional power
> >>>> stations to pump water into high level reservoirs
> >>>> to run hydroelectric turbines at peak demand times, storing energy
> >>>> as compressed air in salt domes is another option, use it to
> >>>> supply  the energy needed to get gas turbines running.
> >>>>
> >>>> None of these, however give us any kind of solution for automotive
> >>>> transport - when the oil runs out we're going to back with sailing
> >>>> ships and steam engines again, individual or personal
> >>>> transportation will be the rich man's game.
> >>>
> >>>
> >>>
> >>>
> >>> _______________________________________________
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> >>>
> >>>
> >>
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> >
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