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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.

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.

Metzger R.L.,Radiation Safety Engineering Inc. | van Riper K.,White Rock Science | Pouquette P.,Radiation Safety Engineering Inc.
Journal of Radioanalytical and Nuclear Chemistry | Year: 2015

Evaluation of food products by gamma spectroscopy requires a correction for food density for many counting geometries and isotopes. An inexpensive method to develop these corrections has been developed by creating a detailed model of the HPGe crystal and counting geometry for the Monte Carlo transport code MCNP. The Monte Carlo code was then used to generate a series of efficiency curves for a wide range of sample densities. The method was validated by comparing the MCNP generated efficiency curves against those obtained from measurements of NIST traceable standards, and spiked food samples across a range of food densities. © 2015 Akadémiai Kiadó, Budapest, Hungary

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.

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