[ RadSafe ] [NucNews] Which nuclear technology has future?

George Stanford gstanford at aya.yale.edu
Mon Jul 2 13:46:44 CDT 2012


      You are right in that the "I" part has yet to be demonstrated 
on a commercial scale, although it has been tested on a laboratory 
scale.  (Remote operation of the recycling facility worked 
successfully at EBR-II for many years.)  The PRISM is indeed only the 
reactor part, but GEH sees a permanently functioning PRISM plant as 
one that incorporates a pyroprocessing facility.
      You are also correct that the GEH proposal for the UK does not 
yet encompass the pyroprocessing of IFR fuel.  However, it does 
involve appreciably more than "just the reactor & steam 
plant":  there will be a facility to convert oxide fuel to metal and 
fabricate the IFR fuel elements -- much of what is needed to process 
used LWR fuel for consumption in IFRs.  For the "disposition" of the 
current Pu inventory, the only cost to the UK government will be a 
charge per kilogram of Pu treated.
      If the GEH proposal is accepted and the plant performs as 
expected, one would hope that people will come to appreciate the 
significance of the fact that the UK already has enough uranium to 
power the country for centuries, given the inclusion of pyroprocessing.
      You ask,
>"What fraction of plutonium and other TRUs slip
>through the processing & into the waste stream?
>"...at what cost, for each factor-of-ten improvement?
      Comment:  You're right, of course, that there's a cost 
trade-off.  The goal is loss of less than one percent of the 
actinides.  The costs are not yet determined.  What can be achieved 
at a given cost is determined, in part, by the burnup per cycle.  The 
IFR development program was aborted before the burnup limit with the 
HT-9 cladding could be observed, but it clearly was considerably 
greater than the ~20% achieved
>"And if we don't care that much about the waste
>stream, then why bother reprocessing at all?"
      Comment: But we do seem to care a lot about the waste stream, 
don't we?  In the public mind, dealing with the "waste" is foremost 
among the concerns about nuclear power.
      TerraPower's TWR is based on IFR technology -- in effect, it is 
a very large and heavy IFR whose conceptual design is still 
evolving.  The only significant claimed advantage over a real IFR is 
its (currently) proposed indefinite postponement of recycling -- and 
that's not necessarily an advantage.  At 50% burnup versus, say, 98% 
for the IFR, that's 50 times as much actinide waste per unit energy 
produced.  (Arithmetic: For 50 GWe-yr of energy, the TWR starts with 
100 tonnes of actinides and leaves 50 tonnes of actinides, while the 
IFR starts with 51 tonnes of actinides and leaves one tonne of actinides.)
      I hope that helps.
      --  George


At 08:51 AM 7/2/2012, Jaro Franta wrote:
Apparently nobody wants to build the "I" part of IFR.
In which case the claim that "the PRISM is an IFR" seems dubious -- there is
no *integral* fuel processing & re-fabrication plant.

Specifically, I was disappointed when I learned earlier this year that the
GE Hitachi Nuclear Energy proposal for the UK involves just the reactor &
steam plant, NOT the fuel processing & re-fabrication plant.
That makes it little more than any other SFR......

"The waste is much the same as that produced by new light water reactors,"
said Eric Loewen, chief engineer on the Prism project.

 From past experience, its already a big hurdle to sell fast reactors to
politicians & public.
Adding reprocessing would probably make the job twice as tough.

I also think its important not to forget the significant challenges of
handling, dismantling and re-fabricating SNF robotically, whilst maintaining
cooling throughout the process (presumably submerged in a pool of sodium).

We usually hear only about the electro-reprocessing facilities, but there
must be more to it than that.

For example, look at the robotic infrastructure for handling irradiated fuel
in reactors where on-line refuelling is performed, such as in Candu
The robotic fuelling machines are some of the most expensive pieces of
equipment in the plant ! .....and all they do, is just move fuel bundles
around: no disassembly, chopping up, conversion to fluoride salts,
electro-refining, re-conversion to metal and later re-casting and
re-fabricating the fuel elements.

Defective fueling machines have in the past put Candu plants out of action
for extended periods, while the robotic mechanisms are repaired.
With so little information about IFR/PRISM available publicly, we can only
speculate what sort of problems a more complex robotic system, working in a
pool of opaque, flammable sodium coolant could cause (the fueling machines
are continuously cooled, as the radioactive fuel inside generates a lot of

In the book "Plentiful Energy - The story of the Integral Fast Reactor"
(http://bravenewclimate.com/2012/02/19/ifr-fad-10/ ) it is claimed that
"spent metal fuel can be processed with much cheaper techniques" than oxide
That isn't really saying much !
What fraction of plutonium and other TRUs slip through the processing & into
the waste stream ?
...at what cost, for each factor-of-ten improvement ?
And if we don't care that much about the waste stream, then why bother
reprocessing at all ?

Evidently, that is the intent for the UK bid.

Wouldn't it be better to limit the fuel processing to a simple
"melt-refining" that just removes the fuel-damaging, neutron-absorbing
volatile fission products ?
According to TerraPower (the Bill Gates outfit), periodic melt refining in
their TWR reactor allows burn-ups exceeding 50% to be achieved.
If the "melt-refining" is carried out in recycled fuel rod tubes (ie. no
chopping up, fluoride conversion, electro-refining & re-fabrication), then
the reprocessing plant essentially disappears.
(See http://lumma.org/temp/Ellis_et_al-TWRs_A_Truly_Sustainable_Resource.pdf


-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of George Stanford
Sent: July-02-12 1:13 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] [NucNews] Which nuclear technology has future?

Dear  Dr. Parthasarathy:

       Thanks for your note.  It raises some interesting thoughts.  I
intersperse some comments below.
At 10:06 PM 7/1/2012, parthasarathy k s wrote:
 >Dear Dr Stanford,
 >Who will spend money for the developmental efforts? Uranium is cheaply
 >available. LWR is not certainly the best; but it is readily available.
 >Funding for R & D on newer technologies will have to come from the
 >Government. I recall your comments that IFR technology is more
 >completely developed compared to the breeders.
GSS:  (a) Actually, the IFR IS a breeder -- or  else a net burner of Pu, or
an "isobreeder," depending on its loading.


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