Joel W. Cannon wrote:
<< First, fusion reactors (as opposed to reactions) do produce
significant radioactive contamination through activation. The very
high energy neutrons (14 Mev) present a challenge to the person trying
to convert the energy of a neutral particle into electricity, and to
find shielding that will stop the neutrons and not fall apart. This
shielding whatever it is will be highly radioactive after it is
finished. The half life of the shielding radioactivity will be less
than that of plutonium but still significant (I believe we are talking
hundreds of years). >>
Thanks for the information, .
If fusion yeilds waste products that only have a half life of a few hundred
years,
that is not bad at all! The main issue with
fission reactors is that the waste products have to be stored for hundreds
of thousands of years. That's approaching geologic time scales. There are
no truly "safe" places to put the waste. It may not occur to some people
on the list, but the Grand Canyon had a very different climate 10000
years ago (considerably more rain). It is not simple to estimate what the
climatic conditions will be at a storage area 100000 year from now. It is
perhaps reasonable to presume that large scale geologic upheavals will
not occur in that time frame, but building a valt to withstand all
foreseeable
problems is a non-trivial matter.
Matters are compounded because most of us I expect, would not like
to leave a massive problem to a future generation due to wanton selfish
lack of foresight, or even complete and utter ignorance (although the
latter is a more forgivable error).
Hence, if your figures are really correct, then I would say that fusion
still has a lot going for it --- a "few hundred years" would be quite
managable as a waste problem, 100000 years is much less so.
The bigger problem, as Glenn said in the first post, and in a follow up
is that we don't have the technology now, and we need it *now* to have
something fully functioning in the near future --- and to make a more
effective evaluation of the technology. We know the breaks of nuclear
power, but everything related to fusion is a question mark.
<<
Is this just a social problem or a public policy problem? If we throw
more money at it, could we make it work? I think not. The crux of the
problem is that you are trying to contain very dynamic electrically
charged particles (a plasma) electromagnetically (laser induced fusion
is somewhat different). In mathematical or physics terms, it is a
tremendous non-linear problem. Non-linear problems are extremely
difficult to solve or to predict. This skepticism has, in part, been
picked up from people who were working in the field.
>>
Please don't read too much into this or infer some
insinuation about yourself in this, but skepticism to me
is an arm chair position. People bring their life's work
to me, and I judge it over tea and crumpets. Perhaps it is
good for dreamers to be shot down particularly when they
lose touch with reality. It is also good to be skeptical
in deciding how to prioritize funding. However, there is
a faith that comes with every attempt one makes in their
chosen toil on this planet, and I think it is important to
suspend at least some level of judgement when people in
their toil are at least showing signs of understanding
the limitations of their dreams.
Perhaps you are right in your skepticism. The fact that
they have worked so long on it without success definitely
shows that it is a difficult problem. I also have a
rudimentary enough knowledge of physics to appreciate
the problems with trying to contain a plasma.
Another approach is perhaps to transmutate the waste, but
that has only led to limited success.
In the end, I think science is about dreams and discovery.
I still have faith that the Lord provides because God as
a gracious and loving God, and that in part is why I
always sign off with
By Grace and Grace alone do we proceed,
Wayne
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