Science: Atomic Five-Year Plan

While its weaponeers are at work in the Pacific (see NATIONAL AFFAIRS), the Atomic Energy Commission is also going after peaceful nuclear power in a big way. Speaking last week to a Washington meeting of the American Institute of Chemical Engineers, Commissioner Henry D. Smyth told about the AEC's five-year plan for hitching the atom to nonmilitary power production. During this period, he said, the AEC intends to build five different power reactors, some large, some small.

One power reactor now in prospect is the 60,000-kw. job announced last fall (TIME, Nov. 2). Commissioner Smyth described it this time in some detail. Its fuel will be "slightly enriched" uranium (more U-235 than in natural uranium), and its moderator and coolant will be ordinary water at 2,000-lbs.-per-sq.-in. pressure and a temperature between 500° and 600° F. This is not high pressure or temperature for a coal-burning steam plant, but it is unusual for a nuclear reactor, and Dr. Smyth anticipates a certain amount of trouble. He does not expect that the plant will produce power at a competitive cost, but he hopes that in practical operation it will show how costs can be cut.

Novel Reactor. The other reactors will be more unusual. One will be a "breeder" designed to make more fissionable fuel (plutonium) than the U-235 that it consumes. It will generate 15,000 kw. of electricity (the experimental breeder at Arco, Idaho generates only 170 kw.), and its pumps and other components will be big enough for a full-scale breeding power plant.

To get high temperature (which favors efficiency) without high pressure, another reactor will have heat-resistant graphite as its moderator and will be cooled by a molten sodium-potassium alloy. Still another will have a novel gimmick. Its cooling water will be allowed to boil, and the steam generated will be used directly to drive a 5,000-kw. turbine. This cuts out the conventional heat exchanger used in the reactor of the submarine Nautilus to generate nonradioactive steam. Dr. Smyth did not say so, but the turbine will probably become so radioactive that it cannot be approached by humans.

Thorium Breeder. The most radical of the reactors will be "homogeneous," i.e., its uranium, instead of being in the form of solid rods, will be a solution of uranye sulfate. Dr. Smyth did not say in what liquid its uranium will be dissolved. A fair guess is that it may be heavy water. Since the reactor will be a breeder, it must be economical of neutrons, and heavy water does not absorb as many neutrons as ordinary water does. Instead of breeding U-238 into plutonium, the excess neutrons from its reacting core will be absorbed in thorium, turning it into fissionable U-233-Thorium is probably more plentiful than uranium, and it has been discussed for years as a promising source of nuclear energy. This is the first time that the AEC has shown by a definite commitment that it takes thorium seriously.