From: jmc@SAIL.Stanford.EDU (John McCarthy)
Subject: Japanese breeder plans
Reply-To: jmc@cs.Stanford.EDU
Organization: Computer Science Department, Stanford University
Date: 28 Dec 92 09:51:52

The following is an excerpt from a U.P. story.

	     Despite domestic and international criticism, Japan
     plans to continue to develop fast breeder reactors.
	     Sources told the newspaper Yomiuri Shimbun that
     Japan's Atomic Energy Commission decided to build a second
     prototype fast-breeder reactor.
	     Japan's first prototype fast breeder reactor, Monju,
     is scheduled to reach its full capacity next October
     operated by the government-run Power Reactor and Nuclear
     Fuel Development Corp. The reactor has been the focal point
     of the country's aggressive program to reduce its dependency
     on foreign supplies of nuclear fuel.
	     The second reactor will be more advanced than Monju,
     the sources told Yomiuri, and constructed by the electric
     power industry with government assistance. This marks a
     shift from the previous policy of letting the private-sector
     electric power industry take the initiative in developing
     fast breeder reactors.
	     Fast breeder reactors contain a type of uranium that
     does not burn as nuclear fuel but are fueled by the spent
     material, plutonium, the most dangerous radioactive material
     according to some scientists and the basis of atomic bomb.
     Critics maintain there is no way Japan will be able to
     consume the more than 80 tons of plutonium it plans to
     create over the next two years.

1. Contrary to the implications of the _New York Times_ "Japan's
Nuclear Fiasco" article, the Japanese are going ahead with the
breeder program.  Good for them.  We'll eventually be buying
nuclear technology from them.

2. The U.P. writer mixes his anti-nuclear opinions into his news
stories on a consistent basis.  The A.P. is a little better about
not letting writers include editorials in news stories.

3. The writer is consistently confused about what a breeder reactor
is.  He has not bothered to learn, although he has been writing
the same story for many months.

A breeder reactor is like any other except for one thing.  It is
more economical with neutrons.  In an ordinary reactor, for each
fission, about .25 neutrons out of the somewhat more than two
neutrons per fission is absorbed by an atom of U-238, converting
it to an atom of plutonium.  Thus the used fuel rods contain
valuable plutonium mixed with the fission products and unburned
uranium.  A breeder reactor absorbs more than one neutron in U-238
per fission.  Thus, as long as there is plenty of U-238, you end
up with more fissionable material than you started with.  The
effect over the long run is that the reactor is burning U-238
instead of U-235.  Uranium contains 140 times as much U-238 as
U-235, so you get 140 times as much energy out of a kilogram of
uranium.  Moreover, since you get so much more energy out of a
kilogram of uranium, it is economical to use much lower grade
uranium ore.  This multiplies uranium resources by another
large factor.

During the early days of commercial nuclear power, it was thought
that the number of reactors in the world would expand much more
rapidly than it did.  For this reason, a shortage of uranium was
projected if non-breeder reactors continued to be the sole kind.
Because fewer reactors were built than expected, and because new
sources of uranium were found, breeder reactors are less urgent
than they were though to be.  Nothing is lost in the long run,
because the depleted uranium produced when uranium is enriched
will be usable in breeder reactors.

Breeder reactors require that the plutonium produced be extracted
and mixed with uranium when reactors are reloaded.  That's what
the Japanese are doing, although they plan to use some of the
plutonium in ordinary reactors.

The scientific error in the U.P. story is in:

	     Fast breeder reactors contain a type of uranium that
     does not burn as nuclear fuel but are fueled by the spent
     material, plutonium, the most dangerous radioactive material
     according to some scientists and the basis of atomic bomb.

The uranium is the same as in ordinary reactors.  However, the
scientific error is unimportant, since the main purpose of the
sentence is propagandistic.

The main question about breeder reactor development is that of
when it will be important to use them.  At the present rate of
building of reactors, it will be quite some time.  However, if
the greenhouse effect turns out to be serious, or if pollution
from burning coal becomes important in the public mind, then
the rate of building reactors will spurt.  Then the price of
uranium will go up, and those countries that don't have their
own breeder reactor programs will end up buying them from Japan
and France.
--
John McCarthy, Computer Science Department, Stanford, CA 94305
*
He who refuses to do arithmetic is doomed to talk nonsense.