Thoron versus radon: measurement and dosimetry

Two new instruments were developed for the U.S. Department of Energy Environmental Science Management Program (EMSP) to perform more detailed exposure assessment measurements at Fernald, OH. Fernald is a former uranium processing facility undergoing remediation. The instruments are a miniature radon and thoron detector, and a miniature particle size spectrum analyzer. Ongoing measurements of both thoron (220Rn) and radon (222Rn) gas are now being made at four locations: (1) at Fernald; (2) at the New York City National Weather Service site, used as a quality control (QC) site; (3) at a private home in Bangkok used as a QC site; and (4) at a research center and rare earth development facility processing monazite ore near Bangkok. Particle size distribution measurements are presented for two locations: at Fernald and at the Rare Earth Facility near Bangkok. Continuous radon and thoron measurements were made at all sites for at least 1 year and the bronchial dose is reported.