Fuel Running Out

The present-day nuclear reactor is very inefficient in the use of uranium. It utilizes only about 1 percent of its energy content in producing power. As a result, U-235, the uranium isotope used in nuclear fuel, is rapidly being depleted. Science Digest of last February observed: “Ordinary nuclear plants are consuming available uranium so quickly that by 1980 we’ll probably be scraping bottom.”

The Atomic Energy Commission’s Robert Nininger recently expressed this ominous outlook: “Things could come to a slow grinding halt unless we could get uranium overseas. Mathematically, we could be taken out to about 1982.” Other estimates indicate the supply could last a little longer.

What does this mean? Surely all these nuclear plants are not being planned and built knowing that the whole nuclear fission system of power generation could soon grind to a halt. How is this problem supposed to be solved? Will it result in lessening or increasing possible hazards to man?

A Different Kind of Reactor

The fast-breeder reactor is being looked to as the solution of the uranium shortage. Peter Mummery, head of a reactor development center in northern Scotland, said of breeder reactors: “We are putting all our money on them.” The United States has taken a similar position.

In his June 4, 1971, message to Congress on the energy crisis President Nixon asserted: “Our best hope today for meeting the Nation’s growing demand for economical, clean energy lies with the fast-breeder reactor.” The president asked Congress to pledge $2,000,000,000 in federal funds over the next ten years to develop a commercial model. But how is the breeder reactor intended to solve the fuel problem?

It is by producing more fuel than it uses. The breeder reactor can actually do this, thus the name breeder. This may at first sound impossible, but how it can be accomplished is appreciated when one realizes that new elements are formed during the fissioning process.

In the conventional reactor’s operation, U-235 atoms split and form smaller radioactive elements, as well as releasing neutrons. But U-238 atoms, instead of splitting, capture a neutron and are transformed into fissionable plutonium, an element not ordinarily found on earth. In a conventional reactor a relatively small number of U-238 atoms capture neutrons, thus producing only a little plutonium. But in the breeder reactor more U-238 is transformed into plutonium than the amount of fissionable fuel consumed! How is this made possible?

It is due to the speed with which the neutrons travel. In the breeder reactor, rather than having a material of some sort to slow down the neutrons, they are left to travel rapidly. (That is why it is called a fast-breeder.) Thus when the neutrons hit and split either U-235 or plutonium, they dislodge from the fissioning atoms more neutrons than occurs in a conventional reactor. This makes more neutrons available to be captured by the plentiful U-238, and hence there is a net increase in the production of plutonium, which is the fuel used in breeder reactors.

Because of thus breeding fuel, the chairman of the A.E.C., James R. Schlesinger, said: “The breeder will be able to provide electrical energy for tens of thousands of years.”

When one considers the fuel used, the seriousness of any malfunction can be appreciated​—the plutonium fuel being one of the most dangerous substances in existence. And to think that each reactor will contain thousands of pounds of it! Dr. Edward Teller observed in Nuclear News, August 21, 1967:

“In order that it should work economically in a sufficiently big power-producing unit, it probably needs quite a bit more than one ton of plutonium. I do not like the hazard involved. I suggested that nuclear reactors are a blessing because they are clean. They are clean as long as they function as planned, but if they malfunction in a massive manner, which can happen in principle, they can release enough fission products to kill a tremendous number of people.”