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Port Washington North, AZ, United States

Metzger R.L.,Radiation Safety Engineering Inc. | Eckerman K.F.,Oak Ridge National Laboratory
Journal of Radioanalytical and Nuclear Chemistry | Year: 2013

Default values for the solubility of various compounds in the lung are provided in publications of the International Commission on Radiological Protection as absorption types to characterizes the potential uptake of radionuclides to blood. The default assignments are conservative and reflect compounds likely to be encountered in the workplace. In practice, solubility profiles for many compounds, both natural and man-made, are complex, with a fraction of the compound in each absorption type, denoted as F, M, or S. Only soluble compounds of tritium and iodine can be reasonably assumed to be of one absorption type. The assumption of a single absorption type for airborne distributions of solid particulate matter can introduce order of magnitude errors in internal dosimetry calculations. The problem is particularly acute for isotopes with dual toxicity (e.g. uranium which is both nephrotoxic and radiotoxic), and when a dose estimate must be derived with only a single bioassay measurement. For inhalation exposures during an accident, treatment decisions frequently must be made quickly to be effective. While much work has been done to develop rapid bioassay methods that will provide data in a clinically useable timeframe, little consideration has been given to the magnitude of the error in the dose estimate resulting from the assumption of the default solubility profiles. © 2012 Akadémiai Kiadó, Budapest, Hungary. Source


Hirayama H.,High Energy Accelerator Research Organization | Nakashima H.,Japan Atomic Energy Agency | Morishima M.,Radiation Safety Engineering Inc. | Uematsu M.,Toshiba Corporation | Sato O.,Mitsubishi Group
Journal of Nuclear Science and Technology | Year: 2015

Progress in calculation methods for radiation shielding are reviewed based on the activities of research committees related to radiation shielding fields established in the Atomic Energy Society of Japan. A technological roadmap for the field of radiation shielding; progress and prospects for specific shielding calculation methods such as the Monte Carlo, discrete ordinate Sn transport, and simplified methods; and shielding experiments used to validate calculation methods are presented in this paper. © 2015 Atomic Energy Society of Japan. All rights reserved. Source


Rez P.,Arizona State University | Metzger R.L.,Radiation Safety Engineering Inc. | Mossman K.L.,Arizona State University
Radiation Protection Dosimetry | Year: 2011

Systems based on the detection of Compton backscattered X rays have been deployed for screening personnel for weapons and explosives. Similar principles are used for screening vehicles at border-crossing points. Based on well-established scattering cross sections and absorption coefficients in conjunction with reasonable estimates of the image contrast and resolution, the entrance skin dose and the dose at a depth of 1 cm can be calculated. The effective dose can be estimated using the same conversion coefficients as used to convert exposure measurements to the effective dose. It is shown that the effective dose is highly dependent on image resolution (i.e. pixel size).The effective doses for personnel screening systems are unlikely to be in compliance with the American National Standards Institute standard NS 43.17 unless the pixel sizes are >4 mm. Nevertheless, calculated effective doses are well below doses associated with health effects. © The Author 2010. Published by Oxford University Press. All rights reserved. Source


Grant
Agency: Nuclear Regulatory Commission | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 187.57K | Year: 1995

WE PROPOSE TO DEVELOP A PORTABLE MONITORING SYSTEM CAPABLE OF DETECTING TRACE QUANTITIES OF RADIONUCLIDES IN SOILS USING A HIGH RESOLUTION CADMIUM TELLURIDE ARRAY DETECTOR AND A RUGGED MULTICHANNEL DATA LOGGER. THE PROPOSED MONITORING SYSTEM BUILDS UPON THE DESIGN OF A SIMPLE MONITOR DEVELOPED TO AID IN THE DECONTAMINATION AND DECOMMISSIONING OF A URANIUM PLANT. THE SIMPLE SYSTEM IMPROVED THE SPEED AND EFFICIENCY OF CONTAMINATION SURVEYS DURING DECOMMISSIONING. WHEN CONFIGURED WITH A SHIELDED 2 MM NAT CRYSTAL, THE UNIT WAS ALSO ABLE TO DETECT TRACE QUANTITIES OF URANIUM IN SURFACE SOILS AND PRODUCED SIGNIFICANT COST AND TIME SAVINGS IN THE FINAL ENVIRONMENTAL RELEASE SURVEYS FOR THE PLANT PROPERTY. WHILE SUCCESSFUL IN ITS INTENDED APPLICATION, THE SIMPLE MONITOR HAD SIGNIFICANT LIMITATIONS IN DETECTOR RESOLUTION, DATA ACQUISITION, AND PORTABILITY THAT RESTRICT ITS USE AS A GENERAL PURPOSE MONITOR FOR FIELD USE. THE PROPOSED MONITORING SYSTEM SHOULD HAVE THE CAPABILITY TO ACCURATELY TRACK TRACE RADIOACTIVE CONTAMINANTS AND NATURALLY OCCURING RADIONUCLIDES IN SOIL, AND HAVE THE ADVANTAGE OF BEING SMALL, WATERPROOF, AND COMPLETELY FIELD PORTABLE. SINCCE THE FEASIBILITY OF THE MONITORING SYSTEM HAS ALREADY BEEN DEMONSTRATED, WE PROPOSE TO BEGIN DEVELOPMENT OF THE SYSTEM IN PHASE I.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.84K | Year: 2001

65589 In order to efficiently plan for the decontamination of DOE facilities, the three-dimensional distribution of radioactive contaminants must be determined. Samples could be obtained for laboratory analysis, but this method could expose workers to radiation as well as spread contamination. On-site in situ measurements are preferred; however, no method currently exists for the in situ characterization of the contaminant depth profile, without a priori assumptions about the profile. The deficiency will be addressed by using gamma-ray spectroscopy with a number of collimators, each restricting the field-of-view to a different range of angles with respect to the surface normal, to characterize radioactive depth distribution in three-dimensional field surveys. Phase I will: (1) model the detector system to optimize the number and design of the collimators; (2) determine the minimal detectable activity using laboratory measurements of bare and attenuated sources, and (3) test the detector system on ground contaminated with Uranium mine tailings. Commercial Applications And Other Benefits: A detector system providing three-dimensional, in situ characterization should find use in the cleanup of radioactive contaminants from nuclear facility sites, Uranium mines and mills, reactor structures undergoing decommission, and from thick objects, such as waste drums. Remotely operated detectors can be built to avoid worker exposure.

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