Dose Rate Measurements for Californium-252
C. R. Hoffman, Y. D. Harker
The Portable Isotopic Neutron Spectroscopy (PINS) Chemical Assay System was developed at the Idaho National Engineering and Environmental Laboratory to identify the contents of munitions and chemical storage containers safely and reliably. A component of the system is a Cf-252 source. The need to determine the exact dose rate of a Cf-252 source was a necessity, because the PINS Chemical Assay System is used throughout the world; the PINS Chemical Assay System users, as well as the countries the PINS Chemical Assay System is used in, require that dose rate information about the Cf-252 source be available for review. Laboratory measurements were performed and compared to modeling calculations for the gamma and neutron dose rate information. A 1-µg Cf-252 source was measured at a height of 96 cm from the floor in a laboratory. Measurements began at 30 cm from the source and continued out for 305 cm (when possible), in increments of 30 cm. This experiment determined the dose rates for five configurations: the source, the source inside a Type A shipping container from the manufacturer, and the source in the shipping container within a 2.5-, 5.1-, and 7.6-cm borated polyethylene box. When shielding is applied, the largest contributor to the dose rate to the general public at 305 cm from a Cf-252 source is the gamma component (0.54 µSv/h), and the dose rate from the neutron component is 0.4 µSv/h.
This abstract was presented at the 38th Annual Midyear Meeting, "Materials Control and Security: Risk Assessment, Handling, and Detection", Advances in Instrumentation, Materials Detection and Measurement Session, 2/13/2005 - 2/16/2005, held in New Orleans, LA.