[Leica] RE: LUG Digest, Vol 31, Issue 221

[abridge at gmail.com (Adam Bridge)]

When Uranium is fissioned two different elements are created and each
of these elements is unstable (usually quite seriously unstable) and
so they decay into different nuclides by various mechanisms, all of
which give off serious amounts of gamma radiation. The half-lives of
these fission products vary but the entire chain takes tens of
thousands of years to reach low-level proportions. The spent fuel
isn't explosive although it does produce heat as a result of the
radioactive decay. They don't burn, in general they are metals

The amount of radiation in a reactor core which has never been
critical, that is to say a self-sustaining nuclear reaction has never
happened in it, is quite small. Before the core was loaded into PARCHE
I was able to look up inside it with no protection except for the
requirement to keep everything VERY clean.

But at the end of life the amount of radioactivity is quite vast -
many mega-Curies of radioactivity. (The Curie itself is a huge amount
of radioactivity, it represents a certain number of disintegrations
per second. Normal limits for things are normall expressed in
micro-micro-Curies to give you an idea.)

As a rough approximation, if you are 1 meter away from a 1 Curie
source of gamma-emmiting you'll receive an exposure of 1 REM/hr. REM
is a measure of biological damage produced by radiation.

The limit for non-radiation workers are .1 REM/year over and above
what you get from normal background radiation - ie cosmic rays etc. If
you live at altitude you get more than if you live at sea level for
example. Medical/Dental x-rays aren't counted in this either. You
typically get about 200 mili-rem from natural souces - radon gas which
happens naturally is the biggie - and 40 mili-REM from x-rays per
year.

An exposure of (oh boy these numbers are hazy, it's been a long time)
of 50 REM over a short period will produce identifiable changes in
your blood. 100 Rem acute will make you ill, the threshold of
mortality is 150 REM and I think the 50/50 dose is 500 REM IF you get
the best medical treatment - meaning 50% of the people exposed will
die. 100% mortality is 800 REM.

Radioactive waste from nuclear reactors is in the realm of mega-REM.
The decay of the fission products produces heat. Many of the elements
are themselves corrosive. So it's a tricky problem - especially if you
want to have something stored unguarded. Most fuel-rods are stored
deep under water in pools that are on the grounds of the reactor plant
that produced them. In fact, in the US this is where they have to STAY
since there is no long-term storage facility.

As you might guess they are not easy to steal, either. Somehow you'd
have to take over a facility, find a big lead container, use remote
handling equipment, remove the rods, put them  into the container,
move them. They are typically in stainless steel or zirconium cladding
of some sort or other. Trying to grab one without the remote handling
would be seriously ugly for the people attempting it. It ain't like
the movies.

I hope this was useful and not too technical. My days as a reactor
operator are three decades past. I know that new units of measure are
now included in the SI system but I haven't had a reason to keep up.

Adam Bridge

On 2/2/06, Raimo K <raimo.m.korhonen@uusikaupunki.fi> 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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