Re: breeder reactors (was: Re: Breaking News: World is 10 deg chillier)

Date: Fri Jan 26 2001 - 06:03:51 MST

"Ross A. Finlayson" wrote:

> Once is reached critical mass, there is no reason to discourage enough
> generation of isotopes to renew the mass.

I don't know what are you saying here, and I'm certainly no nuke engineer,
but breeders are rather dangerous customers. They have no moderator/use
fast neutrons, and typically liquid sodium in the primary cooling circuit.
Sodium melts at about 98 deg C, so you have to keep the primary coolant
hot whenever the reactor becomes critical, orelse a solid block of
sodium can suddenly block circulation, by becoming stuck inside an orifice.
Tons of liquid sodium in the primary circuit hot enough to generate
high pressure steam for the turbine does not strike me as especially
safe, considering the heat exchanger surface is mechanically stressed
due to high pressure and the hydrothermally accelerated corrosion as
well as neutrons screwing up the lattice integrity peu a peu. These
are very harsh conditions, and the system as a whole does not fail
gracefully. The smallest leak would make really hot sodium meet hot
water/steam, resulting in a very violent reaction, suddenly creating
lots of hydrogen in a confined space. This means you'll have

a) an explosion, and probably a very large, nasty chemical fire (you
   can't stop the reaction easily, since in case of a leak you can't
   separate sodium from water), and possibly a secondary hydrogen-air
   explosion, which is easily capable of blowing the containment into
   large airborne chunks

b) loss of primary coolant. Can become rather painful, if you have
   simultaneous case of containment breach and reactor core gone
   china, on the background of lots of pretty pyrotechnics.

Also, the breeder is not well-behaved to respect to maintaining
criticality (notice that the Chernobyl accident was caused mostly
by a) highly unstable criticality in low power regime b) paradoxical
reaction to absorber rods while in that regime). Water-cooled and
gas-cooled HTR type of reactors automatically leave criticality as
core temperature goes up, this is not true for fast neutron breeders.

In short, the breeder is a really, really hairy technology, potentiating
the classical nuke power problems. Friends don't let friends use
fast breeders.

Even the supposedly benign HTR has it got its slew of problems:

for a more positive view:

As to fast breeders, try these:
generic information, superficially rather polemic:

As always, Google is your friend. You can formulate your queries
better as you learn the terminology.

> If there is 25 pounds of plutonium, then it should be kept in a secure
> container. Any attempt to use it to generate weapons should cause it to become
> inert.

Um, how do you make Pu inert, fast? By blowing it apart with a chemical
explosive, creating a cloud of micron-sized particles? By suddenly
transmuting it?

Even if you glassify it, it can still be extracted.
> Any radioactive material, there should exist the method to cause it to become
> inert. There might exist ways to dampen the various waves and particles of

There's no way to make stuff inert other than by waiting a great long while
and/or dispersing the material widely, preferably burying the diluted result
in the ground.

> radiation.

There's no way to dampen radiation other than by distance and lots of absorbing
matter between you and its source (for time being, let's ignore magnetical
traps which only work for charged particles and not on that scale, anyway).
You're up the creek if the radioactive source has become incorporated inside
your body. For instance, airborne iodine can wreck utter havoc with thyroids
of people living in iodine-deficient countryside, especially young people.
Similiarly, radioactive strontium becomes incorporated into bone apatite
along with calcium, and irradiates your bone marrow (along with gonads,
the most vulnerable tissue type) from the closest possible distance.

Notice that a molecular machine at relativistic speed also has to learn how
to deal with constant irradiation. Error-corrective encoding and constantly
rebuilding itself while separating out the hot isotopes is probably the
way to go.

This archive was generated by hypermail 2b30 : Mon May 28 2001 - 09:56:25 MDT