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INTRODUCTION

Radioactive isotopes are, on occasion, intentionally added by manufacturers of electron tubes to improve tube performance. For this reason, manufacturs may be required t o determine the total radioactivity in microcuries per tube (µc/tube) to comply with existing Federal regulations.

It is usually impractical to measure the radioactivity with any degree of precision, The radionuclide is often surrounded by electrodes, spacers, and an envelope such that the geometry considerationspreclude a realistic calibration of a measuring device; and the amount of radionuclide intentionally added in the tube is often so small that the amount of radiation is difficultto discern from the normal background radiation that exists in the atmosphere.

Therefore, the radioactivity for electron tubes shall be determined by a calculation technique in terms of the known radionuclides which have been intentionally added to the electron tube to either increase tube life or to improve the overall tube perforniance.