The article describes the construction and initial operation at the Robert A. Taft Sanitary Engineering Center of a multipurpose steel room, 12 x 8 x 8 ft (LWH) and constructed of 5-in. plate. The facility can be used to count a wide variety of objects exposed to environmental radioactivity, including large quantities of environmental samples, animals such as guinea pigs and cats, and human beings.The room is divided into two compartments by a movable inner wall, so that comparative studies on crystal arrangement, sample geometry, and background may be performed, Pertinent design aspects of the room are described and specifications relative to radiological and magnetic field effects on fixed or scanning detector systems are presented in detail. The problem of obtaining steel suitable to meet the stringent specifications is discussed, as are the various aspects in which this facility differs from other similar systems. The main detection system, including the crystal, is described in detail.Initial results of studies of background as a function of crystal location and orientation are discussed and sample counting reproducibility data are given. The crystal light pipe, radioactively clean steel, and the shield location make the background one of the lowest known,0.221 cpm/cm3 of detector over the energy range 0.1-2.0 MeV.
Body burdens of 137Cs were measured in September and October 1966 at two of twenty-one children's homes in which the National Center for Radiological Health determines monthly dietary intakes of cesium-137. Cesiurn-137 intakes in Tampa, Florida, were highest among the twenty-one institutions; in Lake Bluff, Illinois, the intakes were near the average for all institutions. The subjects were thirty children in one home and thirty-five in the other at ages between 6 and 16 years. Height, weight, sex, age, and gross body morphology were recorded for each subject.Cesium-I37 and 40K contents were measured in a truck-mounted shadow shield by means of a 4 in. x 8 in. NaI(T1) detector and a 512-channel pulse height analyzer. The instrument was calibrated with phantoms consisting of 2-lb. boxes of granulated sugar, each with inserted radioactivity standards of 137Cs or *OK. The minimum detectable activity of the instrument system for 13'Cs in children was 1 nCi, and the standard deviation was approximately 0.4 nCi for 30-min counting times. Cesium-137 and potassium body contents and concentrations were log-normally distributed among the children within each institution. Geometric mean values of 13'Cs body burden were 7.7 nCi at the institution where 137Cs intakes were highest, and 3.4 nCi where 137Cs intakes were near the average. Cesium-137 body burdens were related to known intake levels to estimate a mean biological half-life of 46 days.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.