The Chemical World This Week
EVIDENCE OF ELEMENTS 116 and 126 FOUND The squares haven't been filled in on the periodic table yet, but tantalizing evidence for the one-time or present existence in nature of superheavy elements is creating the possibility. Element 114 is already one of those possibilities. And now elements 116 and 126 have been added to the list. The initial evidence for the existence of 116 and 126 (and weaker evidence for others) was presented late last week by U.S. scientists at a meeting of the American Physical Society in Quebec. The evidence is in the form of x-ray "signatures." If substantiated, the finding could have a major impact on nuclear physics and theories of origin of elements and geologic history of earth. Target of the scientists' investigation was ancient crystals, called monazites, from thorium-bearing rocks with an estimated age of 1 billion years. "Giant halos"—large rings of alpha radiation damage—surrounded the crystals. With diameters of 80 to 100 micrometers, the rings correspond to alpha energies of 9.5 to 15 meV—much more energetic than that from known natural elements. For seven years, Robert V. Gentry of Oak Ridge National Laboratory had been trying to explain the origins of the rings. Meanwhile, Dr. Thomas A. Cahill and Dr. Robert G. Flocchini of the University of California, Davis, had been developing a technique under the National Science Foundation's Research Applied to National Needs program and the California Air Resources Board for studying air pollution by looking at characteristic x-rays of the elements. The two lines of research came together when it was recognized that the technique could be applied to studies of the crystals. The x-rays are generated by bombarding the crystals with low-energy proton beams. Recognizing that the Davis cyclotron was not the best suited source of protons for the stable, small 40-micrometer beam needed, the scientists shifted the site of experiments to Florida State University, where a tandem Van de Graaff accelerator was available. There Dr. Neil R. Fletcher, Henry C. Kaufmann, Dr. Larry R. Medsker, and Dr. J. William Nelson Jr., working with Cahill, carried out the experiments, designed largely by Cahill and Flocchini. After several months, they were 6
C&EN June 21, 1976
able to produce proton beams able to probe the crystals with sensitivities of about a picogram. The energies of the resulting x-ray lines match closely—within 20 to 30 eV—those values calculated by Oak Ridge scientists for elements 116 and 126. A lack of viable alternate explanations led the scientists to their present interpretations. Meanwhile, a strong case for the one-time existence in the solar system of element 114 is being built by Dr. Edward Anders of the University of Chicago's Enrico Fermi Institute
(C&EN, May 3, page 27). Anders' group has been working with a tiny mineral fraction of the Allende carbonaceous chondrite, a meteorite that fell in Mexico early in 1969. The small fraction contains what is thought to be decay products of the superheavy element. All of the scientists are proceeding with caution at this point, until all doubts are removed. Reports are of "evidence" rather than "discovery." But the work adds an exciting new dimension to the fast-changing world of nuclear physics. •
Nuclear power grows overseas While the controversy surrounding nuclear power foments unabated in the U.S., foreign nuclear power capacity continues to increase. In the past year, total nuclear power plant commitments outside the U.S. reached a total of 343,355 Mw. That's 17% higher than in the previous year and 56% greater than in 1974, according to the recently completed third annual survey of foreign nuclear reactor capacity by the Atomic Industrial Forum. Light-water reactors, which were pioneered in the U.S., are the most popular choice of foreign countries. Boiling-water and pressurized-water reactors account for nearly 80% of foreign nuclear capacity. This is a slightly greater share than such reactors in last year's survey. The number of countries jumping on the nuclear power bandwagon is growing, too. This year, 41 countries have committed themselves to using nuclear energy to produce electricity, compared to 38 in 1975 and 32 in 1974. This year's newcomers are Indonesia, with commitments for 2900
Mw, Poland (440 Mw), and Turkey (600 Mw). AIF notes that five additional countries have announced long-range plans to build nuclear power plants. However, because details haven't been spelled out yet, AIF hasn't counted Cuba, Kuwait, Libya, New Caledonia, and Peru in its survey. There are 18 countries outside the U.S. that already produce electricity with nuclear power. Of these, Switzerland gets the greatest percentage of its electricity from nuclear reactors, 18% or 1006 Mw. The U.K., however, has more nuclear capacity than any of the others now on line. Its 8097 Mw account for 10% of that nation's total electrical generating capacity. Among all foreign countries, oilrich Iran has moved into fourth place in total nuclear plant commitments. It plans to install 27,200 Mw of capacity by 1994. France continues to be the leader in total commitments, with 39,345 Mw and 47 reactors. Spain and West Germany are second and third. By comparison, the U.S. now has 60
Foreign nuclear commitments up 56% in two years 1976
Capacity in Mw
Operable Under construction On order Planned TOTALS
Capacity
Number of reactors
Capacity
Number of reactors
Capacity
Number of reactors
24,293 50,097
96 77
29,175 59,767
102 85
35,882 85,182
112 117
56,112 90,073 220,575
73 102 348
54,462 150,874 294,278
70 169 426
53,787 168,504 343,355
58 167 454
Source: Atomic Industrial Forum
