Portal de Periódicos da CAPES

THE LOS ALAMOS HUMAN COUNTER

1956; Linguagem: Inglês

E. C. Anderson, R.L. Schuch, J.D. Perrings, Wright H. Langham,

Nuclear and radioactivity studies

To appreciate the need for radiation detectors of greatly increased sensitivity, one has only to note the sharp rise in public concern over the effects of low intensity radiation on man over the past few years. Permissible levels of exposure have been reduced to the point where they are now comparable with the natural background irradiation level. On the basis of these trends, one might predict that not only will the fallout of fission products from nuclear weapons testing and the disposal of reactor waste products be subject to intense scrutiny, but also that there might be a legal prohibition of some of our most popular materials of construction, notably concrete and brick, on the basis of their high content of natural radioactivities such as radium and potassium. (That these materials can produce radiation doses up to several times the average background has been shown by HULTQVIST.') Clearly, this trend necessitates the existence of instruments capable of making measurements at or below the natural levels of radioactivity. The maximum permissible levels are ineffective unless measurements can be readily made to determine the actual exposure levels. Low-level counters are equally important from another viewpoint: namely, the measurement of the natural radiation levels themselves. If detectable biological effects can indeed result from radiation doses comparable to natural background, then studies of populations exposed to different natural background irradiation may be a fruitful and indeed perhaps the only possible way of determining quantitatively the relation between dose and effect. Remembering that it is common to speak of possible damage with a frequency of incidence as low as 1 per 100,000, it becomes obvious that only by the study of populations of several millions can one hope to obtain significant results without large extrapolations. Present interest in unnatural radioactivities has concentrated on the fallout from nuclear weapons testing, since the question of the degree of hazard represented is already with us. This interest can be expected to shift in the future to the disposal of reactor wastes. As has been pointed out, a 100 MW (heat) reactor will produce in the course of one year of operation a total quantity of fission products equal to that produced by the detonation of a one-megaton fission bomb. If the United States produces 20,000 MW from reactors in 1965,2 the fission products requiring disposal would be equivalent