Radiation Protection: Support of the Navy Dosimetry Program

Summary

NIST air kerma measurements are provided to support the safety of U.S. Navy personnel through the Navy’s Monitoring Program for Occupational Exposure to Ionizing Radiation.

Description

Left photo shows five TLD dosimeters mounted on a PMMA Slab Phantom during irradition. Right photo shows the inside of the TLD dosimeter when the rectangular holder (black case) is fully opened: the top half of the rectangular holder contains the four phosphor detection elements (white disks of LiF) mounted on the metallic pink colored card while the bottom half of the rectangular holders shows the filters (larger circular disks of Copper, Teflon, Tungsten and Mylar) that end up being next to the detection elements when the holder is closed.

Credit: Ronaldo Minniti/NIST

Since 2010, the U.S. Navy has adopted a personal dosimeter designated as the model DT-702/PD, which was demonstrated to have an improved accuracy, energy discrimination and a lower detection limit than prior Navy designated models such as the DT-5XX/PD and DT-6XX/PD series. This dosimeter is used to monitor Navy personnel for potential exposure to ionizing radiation. NIST helped characterize this new dosimeter prior to its deployment, and the results of this characterization have been published in the journal Radiation Protection Dosimetry (T. J. St. John et al, Radiation Protection Dosimetry (2006), Vol. 120, No. 1–4, pp. 273–2). The newer technology combines the use of filters and four thermoluminescent elements enclosed in a rectangular shaped holder. The quantity of interest used for monitoring occupational exposure is personal dose equivalent. NIST provides continuous support to the U.S. Navy quality assurance through air kerma irradiations and measurements in the NIST reference standard ¹³⁷Cs gamma-ray horizontal beam facility.