Measuring transuranics in the air For further information contact Joe Kordas (422-6809). The U.S. Department of Energy’s Office of Health and Environ- mental Research is interested in improving the sensitivity and response time of air exhaust monitoring systems at nuclearfacilities. At LLNL, we have developed and fielded a very sensitive alpha measurement system for determining the concentration of trans- uranics and other long-lived alpha emitters in the air. In tests at the Rockwell Hanford Operation’s facilities in Richland, Washington, the system proved to be at least 100 times more sensitive than presently available monitors. — Large quantities of long-lived alpha-emitting substances (such as radium, thorium, uranium, plutonium, americium, and curium) are or will be handled at nuclear laboratories, fuel fabrication plants, chemical processing facilities, and future waste repositories. Online monitoring instruments play a critical role in evaluating and minimizing the release of such substances through exhaust stacks to the environment. The monitoring environment An online alpha detection system for stack effluent must be able to withstand high moisture and acidity and yet detect small quantities of long-lived alpha emitters in the presence of a much larger, natural alpha background consisting of the daughters of radon-222 and -220. Radon-222 and -220 are gases, but their daughters are charged and thusattach themselves readily to particles ment System (TAMS), recently that are collected with long-lived developed at LLNL (Fig. 1), is alpha emitter samples. Figure 2 capable of measuring extremely shows an alpha eneray spectrum of small quantities of transuranics this daughter background taken at (elements that have an atomic atmospheric pressure. The colored number greater than 92) or other area indicates where the peak long-lived alpha emitters in short caused by long-lived plutoniumtime periods. TAMS will makeit 239 would fall if it were present. possible to assess both normal and Under normal conditions, at locaaccidental releases rapidly. . tions 1 metre above the ground, radon-222 and -220 concentrations range from 0.04 to 0.4 pCi perlitre (20 to 200 times the 40-h maximum permissible occupational concentration for plutonium-239 A Transuranic Aerosol Measure- ~ in air). 14