Nuclear Energy

Abstract

It is fascinating to contemplate the train of scientific events from the silent therapeutic action of radium emanations, through the devastating explosive force of atomic bombs to the production of harnessed industrial energy resulting from atomic fission. A few pertinent names may be mentioned in this connection. Klaproth isolated uranium oxide from its black ore, pitchblende, in 1789. Becquerel discovered in 1896 that radiation is given out by uranium. Pierre Curie and his scientist wife, Marie Curie, twice a Nobel laureate (Physics, 1903, chemistry, 1911) isolated radium from pitchblende in 1902. Hahn and Meitner observed in 1939 that by splitting the uranium atom by bombarding it with neutrons large amounts of energy were produced. Apropos of the latter, Einstein (1879-1955) formulated the equation E=MC2 where E represents energy, M, mass, and C, the speed of light (186,000 miles per second). This permits the conclusion that “the energy of one gram of mass is sufficient to keep a 1,000-watt electric-light bulb glowing for 2,850 years” (Encyclopedia International, New York, Grolier, 1963). Uranium is a silver-white metal somewhat softer than steel and almost as heavy as gold. Its richest deposits are in the United States (Arizona, Colorado, Montana, New Mexico, South Dakota, Utah, Wyoming), Australia, Canada, Congo, Czechoslovakia, Japan, New Zealand, South Africa. Natural uranium is 99.3 percent nonfissionable, inert 238U and about 0.7 percent fissionable 235U. The latter's atomic fission releases exorbitant quantities of energy: “one pound of uranium being potentially equivalent to more than 1,500 tons of coal (The New Caxton Encyclopedia, London, Thames, 1969). There are some 20 nuclear reactors in the United States. In preparing fuel for them, uranium is extracted from its ore, pulverized and then converted into gas. By heating the latter, 238U and 235U are separated. Then the fissionable 235U content is raised to at least 3 percent (enrichment process). The final product is made into small pellets of the same weight and width and enclosed in metal tubes which are assembled in a predetermined accurate design (fuel bundle). The heat derived from nuclear reaction is used for producing steam and the latter for driving electric generators serving industry. Also, nuclear energy is being used to propel surface vessels and submarines. Health hazards of underground mining of uranium have been recorded in several publications. In individuals who worked in the uranium mines of Schneeberg, Saxony, (Germany) and of Jachimov, (Czechoslovakia) the occurrence of bronchogenic carcinoma reached 50 to 75 percent. Wagoner (Internat Symp Radiol Health in Nuclear Material Mining and Milling, Vienna, 1963) reported that in the United States, among uranium miners working underground for at least five years, ten times more died of lung cancer than expected of all white males of comparable age in the same areas. Other reports and animal experiments confirmed these findings and the carcinogenic role of exposure to uranium emanations. Carcinogenesis has been attributed to the inhalation of radioactive atoms of uranium and their decay products. Archer et al (J Occup Med 15: 204, 1973) noted that lung cancer developed earlier in cigarette smoking uranium miners than in nonsmokers of the same occupation. Most uranium deposits are found in highly silicous sandstone. Consequently, there is a possibility of silicosis in underground uranium miners. Engelbrecht et al (Ann Occup Hyg 2:257, 1960) observed that in rats radioactive mine dust accelerated fibrosis caused by inhalation of silica. This may explain radiologically demonstrable silicosis in uranium miners employed in mines with low atmospheric concentration of silica. As a corollary, it may be mentioned that inhalation of radioactive substances might cause impairment of the defensive function of neutrophilic leukocytes (Halley et al: AMJ Path 75:61, 1974) and perhaps accelerated aging.