Published: Jan 1960
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This Symposium on Radiation Effects and Radiation Dosimetry was sponsored by ASTM Committee E-10 on Radioisotopes and Radiation Effects as part of a continuing effort to foster communication and promote development in these two related fields. Although both radiation effects and radiation dosimetry are more than a half-century old, they are relatively new and rapidly developing technologies when viewed from the standpoint of the requirements posed by the development of nuclear energy. In view of the pertinence of these developments to the Society's interests and of the increasing need for testing standards, Committee E-10 has considered the sponsoring of symposia on these two fields one of its prime responsibilities. The present symposium was the fifth presented before the Society in recent years. In the organization of the symposium, an attempt was made to obtain information representative of the trend in the past few years to analysis and experimental verification of principles and to critical examination of accepted notions. The five papers in the radiation effects category include two that present recent experimental data on fuel elements and steels and three that deal with parameters that influence the production of effects. One of the few references to effects dependent on the rate of irradiation is included in the description of the performance of Enrico Fermi fuel pins; the results are interpreted, in part, in terms of an effect of rate of fissioning. A second paper describing experimental work presents extensive data on the Charpy V and drop-weight test transition temperatures of irradiated steels and weld metals. In addition to establishing that the effects measured by the two tests are related in much the same manner in irradiated and unirradiated steels, evidence is also presented of considerable discrepancy in the results from exposures in different reactors at the same dosage of fast neutrons (E ≥ 1 Mev). These discrepancies confirm the doubts that have existed on the adequacy of dosages in terms of (≥1 Mev) neutrons as a true measure of exposure. This same problem is considered theoretically in two papers on the importance of the neutron spectrum in producing effects in non-organic solids. It is concluded in the first of these papers that the spectrum must be defined in order to predict adequately the production of interstitial-vacancy pairs. Extensive computations are presented in the second paper to show the variation in the number of displaced atoms produced in steel by different neutron spectra and it is indicated that neutrons of energies less than 1 Mev are a significant factor in damage to metals. The other paper of this group also considers the role of molecular weight, molecular structure, sample thickness, and reaction mechanisms such as diffusion in radiation stability of organic polymers.
Collins, C. G.
SupervisorSymposium Chairman, General Electric Co., Cincinnati, Ohio