1982 Volume 31 Issue 12 Pages 641-647
The dispersal rates of radioisotopes under normal chemical operations were determined with a view to obtaining a fundamental information, which will be applicable to reasonable design of laboratory and safety handling of radioactive materials. A total of 16 samples was selected from widely used radioisotopes. The dispersal rate is defined as the ratio of radioactivity released from the vessel in a unit time to whole radioactivity.
The results showed that the dispersal rates varied widely according to nuclide and chemical form. The higher values were obtained from 3H (amino acid mixture), 14C (amino acid mixture), 35S (cysteine) and 75Se (selenomethionine) with average levels ranging from 4×10-5/h to 7×10-4/h. The values of radioiodines such as 125I (sodium iodide), 125I (triiodo-thyronine) and 131I (sodium iodide) ranged between 4×10-6/h and 2×10-5/h. The lower values were observed for 32P (phosphoric acid), 35S (sodium sulfate), most nuclides of the metallic elements, etc., in which the values lied in less than the order of 10-7/h.
On the basis of these experimental evidences, the relationship between the dispersal rates and the natures of nuclides and of chemical forms is discussed.