Re: I'm hearing bad things about breeder reactors

From: Dez Akin (dezakin_at_usa.net)
Date: 06/11/04 

Date: 11 Jun 2004 01:34:58 -0700

"Eunometic" <eunometic@yahoo.com.au> wrote in message news:<ChZxc.1133$sj4.1070@news-server.bigpond.net.au>...
> "brianb" <bri1600bv@hotmail.com> wrote in message
> news:68a6629.0406090711.701863fd@posting.google.com...
> > eunometic@yahoo.com.au (Eunometic) wrote in message
> news:<e935396a.0406081726.2b818661@posting.google.com>...
> > > bri1600bv@hotmail.com (brianb) wrote in message
> news:<68a6629.0406080759.931460d@posting.google.com>...
> > > > They're saying that they could never work out the kinks and that
> they
> > > > are incredibly expensive etc.
> > > >
> > > > Are breeder reactors in general more expensive than non
> breeders, if
> > > > they CAN work out the kinks?
> > > >
> > > > Does anyone know what the current status of research and such
> is?
> > > >
> > > > Is it only breeder reactors that can burn plutonium? Or is the
> idea
> > > > that by turning U238 into plutonium in a breeder that this
> plutonium
> > > > can be burned elsewhere? I guess I'm confused about the
> difference
> > > > between "breeder reactor" and "reprocessing". Anyone know?
> Thanks in
> > > > advance.

Breeder reactors suck now because uranium is dirt cheap, we have
working designs for light water reactors that are competitive, and
designing new reactors carries significant capital risk. The
opportunity cost is too high given the price of uranium.

> > > All of the breeder programes were cut short of their full
> development
> > > and test cycle as instigated. The IFR for instance was cut down
> by
> > > Jimmy Carter of political reasons not technical or economic ones.

Thats not to say technical or economic reasons didnt exist. If they
did, the market would be running breeders.

> The
> > > Japanese even offered to continue funding the research. The IFR
> was
> > > very proliferation resistent becuase the pyro-processing can't
> produce
> > > pure plutonium and never left the reator building however the fear
> was
> > > that such reactors would ultimetly spread the abillity of other
> > > countries to produce bombs.
> > >
> > > Yes there concerns relating to corrosion reistence of materials
> but
> > > saying that there are problems that need to be solved is not the
> same
> > > as saying that those problems are difficult to solve. For
> instance
> > > you can't test the corrosion resistence of various alloys and
> > > materials unless you actualy have a program to test them by
> exposure
> > > to real conditions.
> > >
> > > The IFR (integral Fuel Reactor) was fueled with a mixture of
> enriched

IFR is integral fast reactor. Its a fast neutron reactor and generally
fast neutron reactors are an excuse to make Pu239. Whats integral
about it is that the fuel is reprocessed on site, not in the reactor.

> > > uranium. Over its life the U235 would be fissioned for energy
> while
> > > the U238 would convert into Plutonium at a rate faster than U235
> was
> > > used up. The fuel would occaisionaly be partialy removed and
> > > 'pyro-processed' in the reactor building itself (eliminating a
> > > security issue) and returned to the reactor. As a result the IFR
> only
> > > needed one fueling in its entire life. During pyroprocessing the
> > > 'actinides' were removed and returned to the reactor in a seperate
> > > part where their decay would provide energy and where high flux
> > > neutrons would destroy the actinides.

Pyroprocessing isn't about that... its just replacing the aqueous
reprocessing technique with the molten salt electrorefining. You still
have security concerns; its not proliferation resistant, you have to
pull the fuel out of the reactor. Every solid fuel reactor has this
issue.

> > > Becuase the actinieds were destroyed by 'transmutation' the IFR
> did
> > > not produce long term waste. IE the volume and activity of waste
> is
> > > drasticaly reduced.

You can do the same thing with aqueous reprocessing... IFR is
different in that the fuel rods are metallic instead of oxides, and
molten salt electrorefining is theoretically cheaper. Of course you
need at least an epithermal neutron spectrum to incinerate actinides,
which LWR doesnt supply...

> > > Becuase the IFR needed such little fuel and even produced more
> than it
> > > used the japanese calculated that they could absorb all the
> uranium
> > > they needed into special polymer membranse suspended in the sea.
> > > While the Uranium would be expensice the price of electricity
> would be

Seawater uranium is totally orthoganal to breeder reactors, except
that if getting U from seawater is inexpensive enough, it makes
breeding uneconomical for some time.

> > > hardly effected. They calculated that this would given mankind
> > > millions of years of energy.
> > >
> > > The French reactor 'super phenix' had some problems with tube
> welds
> > > and has only been opperated small amount of time. It was
> restarted
> > > recently for some transmutation experiments. The IFR can never
> have
> > > that problem becuase it has the fuel in tubes suspended in to
> molten
> > > sodium pool rather than the other way around.

Ah, yes... the other problem with the IFR facility... sodium cooling.
Just what you want, a positive void coefficient with most entirely
prompt neutrons. I'm afraid if you must have a liquid metal fast
reactor, the lead-bismuth way is the way to go.

> > Thanks for your reply. Did the IFR ever get to a point where it
> could
> > be made for commercial use? I know they had a plant in Idaho, I
> read
> > an interview with the guy in charge. I think Clinton finally put
> the
> > nail in the coffin.
>
> I believe it got close. You need to build test plants and after that
> pilot plants. There are a lot of practical things to learn. The
> Molten Salt reactor also got close but it had corrosion problems. A
> lot of the issues relate to the reactors breeding but not breeding
> enough but overall the consensus is that these reactors are very
> feasible.

IFR was never 'close' to anything. It was a research testbed for a
variety of technologies all shoved together into one package. In that
sense it was very successful.

The MSRE facility was far closer to being a commercial design. The
corosion problems faced were mostly dealt with with hastelloy and the
tritium migration issue was also dealt with. Really it won't get close
for a long time because waste disposal isn't much more than a
political issue, and uranium is so damn cheap.

> There are VHTGR (Very Hight Temperature Gas Reactors) that are
> breeders. One of the more intersting cycles is the molten lead
> breeder. They can be built up to any size but if kept down to below
> 200MW they can be be built as a self contained capsule that is sealed
> at the factory. The complete unit is shipped and then runs for 20
> year with no intervention completely on passive cooling. It is then
> switched of for a while and shipped back to the factory for disposal.
> the Russians have a lead bismuth one. A chap called Greenspan is
> trying to build one in the USA. Then there are the thermal breeders
> that don't need fast neutrons. There are neutron beam pumped
> breeders.
>
> There is quite literaly dozens of viable ways of building breeders.
> almost to many to choose from.

The only one that is close to being economically competitive is a
molten salt breeder. You need to have online reprocessing to make it
competitive, and that means fluid fuel. The rest of them are
interesting research testbeds, and have their niches, but the best way
for doing breeding is the critical MSBR. Negitive void coefficient,
mostly delayed neutrons, thermal expansion of the fuel lowers the
reactivity, inexpensive online reprocessing removes the nastiest of
the neutron poisons, high core temperatures that yield high
thermodynamic efficiency, and economic analysis that indicate that its
about as competitive with coal fired plants today, more competitive
than LWR's.

The fast neutron reactors have inertia because they were originally
designed with one purpose in mind: breed Pu239. MSR's (and every
thermal breeder) aren't good at that.

The only reactor technology I like better than MSR's are the
nonexistant fissioning plasma core reactor ideas... if we could find a
way to make sure the plasma flourides don't eat away at the reactor
core vessel. Maybe the fusion plasma physics guys should redirect
their efforts for a while.

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