Evening star., 1947-08-04
Stars. Men and Atoms
Science Is Seeking Way
To Harness Atom Power
Plutonium, Used as Fuel, Is Too Hot
For Known Metals to Hold
Bv Thomas p Honxy

By Thomas r. Henry
Atomic power is too hot to handle.
Development of an atomic boiler which can
hold the more than 10000 degrees centigrads
generated by exploding plutonium without
evaporating into gas or otherwise disintegrat-
ing is the major hurdle In the way of using
atomic f1ssion for industrial power plants
Towards the solution of this problem are be-
Ing directed the major efforts of atomic energy
research. It is revealed in q report Just issued
by the Atomic Energy Commission.
There is no metal now known which meets
the requirements. The highest melting point
Is about 1,100 degrees centigrade This is con-
siderably below the highest combustion tenn
peratures OF coal or oil-about 5000 degrees
but this difficulty Is overcome by suitable COOL
ing systems
No Limit to Heat.
With plutonium however there Is no limit
to the heat which may be generated, depend
Ing on the efficiency Of the process 1t might
conceivably reach 100000 degrees C. The
higher the temperature the more efficient the
power-producing process.
Water. air OF, any well-known engine cooling
medium Is out of the question. Some expert
ments now are in process with certain molten
metals, notably metallic sodium or a potassium
sodium alloy. The temperatures used in these
tests are very high from ordinary standards,
but very low compared to the heat of the ex-
plodng plutonium.
Here lies the great difference between the
use OF this man-made element for destruction
and Tor constructive purposes For the atomic
bomb the container did not matter Once it
was dropped and the reaction started, the
walls were expected to disintegrate In . frac-
tion OF second. Industry would have no use
for evanescent factories.
The problem, however. Is not considered as
insoluble, according to the commission report.
Plutonium Is Fuel
Plutonium, or uranium 235, still must be
considered as fuel, in much the same sense as
coal or oil, since no means has been found for
the direct application of atomic. energy. It
can be made available only by means Of q
heat engine and in the form of steam or
electricity
This considerably reduces the figures CAL
culated for It's efficiency. According to the
Einstein mass-energy conversion formula,
which Is the basic law Of nuclear energy one
pound OF any kind Of matter-plutonium lead
or feathers-should contain energy equivalent
to II 400, 900 900 kilowatt hours. The best chain
reaction process now known, however, is able
to make available only about tenth of per
cent of this-or about IL o0o,o 900 kiowatt hours
pound. No heat engine is more than Is per
cent efncient It turns out eventually that only
about $4,000 kilowatt hours can be expected
from = gram, about 5o0th of a pound. of
plutonium.
This, of course. is millions of times more
than could be expected from any other kind
Of fuel, but the expense Is correspondingly
greater. 1t Is calculated that the cost of power
from plutonium. assuming the problem of an
appropriate container is solved, would be about
the equivalent Of power from coal costing $40
ton.