[ RadSafe ] Spent reactor fuel

Mon Oct 8 14:47:56 CDT 2012

Dear Mike Brennan,

      Thanks for your post.  I'm not sure I  would be connecting 
thermocouples to spent fuel in a
fuel storage pool.  I'd expect I would be connecting thermocouples to  
spent fuel in dry cask
storage???  Heck, you could line the casks up and connect them in  series 
or parallel.

     As for such a system being efficient and  profitable, I would hope the 
system would be efficient
enough and/or profitable enough.  Franz, a research grant application  
could be sent to the
USA Department of Energy to research if an RTG/spent fuel system is  
viable.  Then spend a few years,
with such funding, to research/test the problem.  Think of all the  years 
and $$$ that have been spent
by Team USA trying to get Fusion Plasmas to work.  The RTG/Spent fuel  
system would 
probably generate more energy/power in the first year than fusion ever has  
--- without the $100s
of million dollars pricetag.

     Joe Preisig

In a message dated 10/8/2012 12:55:11 P.M. Eastern Daylight Time,  
Mike.Brennan at DOH.WA.GOV writes:

There  certainly is energy in SNF that can be recovered; the question is
"can it  be recovered economically?"  While the engineer in me wants the
answer  to be "Yes!", I suspect it is not so, for several reasons.   NOTE:
these comments are aimed at the SNF from a BWR, but probably all  apply
to PWR fuel, too.  I say nothing about other reactor  schemes.

1.  Fuel assemblies are designed to be efficient at  transferring heat to
water flowing past them.  This is almost  certainly not the optimal shape
for using thermocouples to turn heat into  electricity.  
2.  There are hundreds of fuel assemblies in a  spent fuel pool, and in
every refueling cycle more are added, and those in  the pool already may
get moved around.  This would be made much more  difficult if each
assembly had wires leading from thermocouples to some  panel.  Also,
while I don't know a lot about making electricity with  thermocouples, I
suspect that under water isn't the best place to do  it.
3.  Anything that complicates moving spent fuel into the pool  will
lengthen the time it takes to refuel the reactor, decreasing  revenue,
and increasing dose to workers.  It is unlikely the value of  energy
recovered would exceed the increased costs.   

If I  were working on a scheme to harvest waste heat from SNF, I would
focus on  using the existing spent fuel pool cooling system to move
heated water to a  heat exchanger, that then used any of several systems
to do something  useful with it.  On the other hand, if I were working on
a scheme to  improve the energy output of a nuclear power plant by
harvesting waste  heat, I would look first at recovering energy from
coolant heading toward  the cooling towers or other heat sink.  The most
efficient use would  be to use the heat directly, such as in greenhouses
or heating or public  and residential buildings, as is done in Siberia.
Next would be some cycle  using some working fluid other than water.  And
fans of the Sterling  Cycle usually chime in that this would be a good
place for their favorite  system (and they are right).  

As much as I agree that we deal  with SNF in a suboptimal way, I suspect
that with current technology  harvesting more energy once it is out of
the reactors isn't the worst  one.  

-----Original Message-----
From:  radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu]  On Behalf Of
JPreisig at aol.com
Sent: Sunday, October 07, 2012 12:36  PM
To: radsafe at health.phys.iit.edu
Subject: Re: [ RadSafe ] Spent  reactor fuel

Dear Franz,

Well, I'm glad to  hear that someone had this idea  many years ago.

Yes, shielding  and handling
are clearly issues in doing what I have suggested.   Efficiency may be  a
concern.

Technology  innovations may allow today what could  not be done back
then.  A  place like Argonne National Lab or INEL could do a small-scale
Spent  Fuel/RTG experiment.  One could probably design some  thermocouple
quick-connect mechanism using magnets of whatever to connect  a
thermocouple to spent fuel and/or the fuel cladding.  Maybe a  robot
could be designed to make such a connection also (No dose to the  humans
involved in the experiment)????

Thanks for your  radsafe post, Franz.  Go have a  beer????

Thanks to Sergio and Roy Herren for their recent radsafe  posts.
Gamma  Knife technology is so very interesting.  Read about it on
Wikipedia  or on the  internet.

Regards,     Joe  Preisig

In a message dated 10/7/2012 10:32:22 A.M.  Eastern Daylight Time,
franz.schoenhofer at chello.at  writes:

Joe,
As far as I rememer, this idea is not new - it was  already  considerer
when I was a teenager (now I am 68). There must  have  been  some
"problems" with shielding,  efficiency and  handling - which are
interconnected...... 

You probably remembe the  sad story, when  woodcutters discovered in
Siberia a Sr-90 generator  and they sat on it,  because it was warm?

Proliferation would be a  small  problem!

Best regards,

Franz

---  JPreisig at aol.com  schrieb:
> Dear Radsafe,
>   
>       Howdy all.  I don't know how viable  the  following idea is.  It 
> certainly would make  anti-proliferation people  nervous.
>  
>     Take some of our (USA or  World???) spent nuclear  fuel,  attach 
> thermocouples to the spent  fuel
> and produce  localized DC electricity sources (like  RTG's???).
Wonder 
what  
> the total USA energy/power
> generated this way would  be???
>  
>     Put solar cells on the roof of  such energy/power  sources and
produce 
> even more  electricity???
>  
>     Regards,     Joe Preisig
>  
>  
>   _______________________________________________
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--
Franz Schoenhofer, PhD,   MinRat
Habicherg. 31/7
A-1160 Vienna
Austria
mobile: ++43 699  1706  1227

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