Accuracy Of External Personnel Dosimetry Systems In Mixed Neutron And Gamma Radiation Fields PDF Download
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| Release | : 1983 |
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Download Accuracy of External Personnel Dosimetry Systems in Mixed Neutron and Gamma Radiation Fields Book in PDF, ePub and Kindle
Estimates of biological effects associated with exposure to external radiation fields are generally based on the measured response of passive personnel dosimetry systems to the incident radiation. The increasing number of persons occupationally exposed to mixed neutron and gamma fields and recent questions concerning the relative biological hazards of different types of radiation have emphasized the need for accurate personnel radiation dose measurements. The performance characteristics of various neutron and gamma personnel dosimetry systems under actual mixed-field conditions have been determined. Analysis of the results indicates that significant inaccuracies can occur in neutron and gamma dose measurements in mixed radiation fields unless dosimeter performance and characteristics of the monitoring environment are considered in dosimeter evaluation. Neutron dose measurement accuracies could be improved by using dosimeters more suited to the anticipated radiation fields, calibrating dosimeters with sources appropriate for the energy spectra to be measured, applying correction factors to account for dosimeter performance in incident radiation fields, and standardizing the basis of reported dose equivalents. With regard to gamma monitoring, intercomparison results indicate that the selection of a basic dosimeter type which is relatively insensitive to neutrons is of great importance for accurate dose measurements in mixed fields.
| Author | : Henri François |
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| Total Pages | : 164 |
| Release | : 1970 |
| Genre | : Radiation |
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Download Personnel Dosimetry Systems for External Radiation Exposures Book in PDF, ePub and Kindle
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| Release | : 1988 |
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Download Twelve Years of Neutron Personnel Dosimetry Intercomparison Studies at Oak Ridge National Laboratory Book in PDF, ePub and Kindle
To provide an opportunity for dosimetrists to test and calibrate their personnel neutron monitoring systems in a variety of incident radiation fields, the staff of the Dosimetry Applications Research (DOSAR) Facility at the Oak Ridge National Laboratory (ORNL) has conducted personnel dosimetry intercomparison studies (PDIS) periodically since 1974 and annually since 1976 (Si82, Sw87). During these studies, personnel dosimeters are mailed to ORNL, mounted on phantoms and exposed to low-level (less than 15 mSv) dose equivalents in mixed-radiation fields mainly produced using the Health Physics Research Reactor (HPRR) at ORNL (Au65), and then returned to the participants for evaluation. Reported dose equivalents are compared to reference values provided by the DOSAR staff and to results reported by individual organizations which made measurements under identical conditions. These intercomparisons, which require no fee and are open to any organization interested in external personnel dosimetry, have provided more data concerning neutron dosimeter performance characteristics in mixed-radiation fields than any other periodic open test program conducted to date. The following text presents a summary and analysis of neutron dose equivalent measurements reported for the seventh through twelfth intercomparisons (1981-1986) using the HPRR as the source of radiation. Particular factors examined include low dose equivalent sensitivity and measurement accuracy for the basic types of neutron personnel dosimeters. 5 refs., 1 fig.
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| Release | : 1981 |
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Download Performance of Neutron and Gamma Personnel Dosimetry in Mixed Radiation Fields Book in PDF, ePub and Kindle
From 1974 to 1980, six personnel dosimetry intercomparison studies (PDIS) were conducted at the Oak Ridge National Laboratory (ORNL) to evaluate the performance of personnel dosimeters in a variety of neutron and gamma fields produced by operating the Health Physics Research Reactor (HPRR) in the steady state mode with and without spectral modifying shields. A total of 58 different organizations participated in these studies which produced approximately 2000 measurements of neutron and gamma dose equivalents on anthropomorphic phantoms for five different reactor spectra. Based on these data, the relative performance of three basic types of neutron dosimeters (nuclear emulsion film, thermoluminescent (TLD), and track-etch) and two basic types of gamma dosimeters (film and TLD) in mixed radiation fields was assessed.
| Author | : National Committee on Radiation Protection and Measurements (U.S.) |
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| Total Pages | : 96 |
| Release | : 1961 |
| Genre | : Neutrons |
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Download Measurement of Absorbed Dose of Neutrons, and of Mixtures of Neutrons and Gamma Rays Book in PDF, ePub and Kindle
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| Release | : 1981 |
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Download Sixth Personnel Dosimetry Intercomparison Study Book in PDF, ePub and Kindle
The Sixth Personnel Dosimetry Intercomparison Study was conducted March 25 to 27, 1980, at the Oak Ridge National Laboratory. Dosimeters from 28 participating agencies were mounted on anthropomorphic phantoms and exposed to a range of low-level dose equivalents (1.8 to 11.5 mSv neutron, 0.1 to 1.1 mSv gamma) which could be encountered during routine personnel monitoring in mixed radiation fields. The Health Physics Research Reactor (HPRR) operated in the steady-state mode served as the source of radiation for six separate exposures. Lucite and concrete shields along with the unshielded reactor were used to provide three different neutron and gamma spectra. Results reported by the participating agencies showed that TLD-albedo and TLD-700 dosimeters generally provided the most accurate measurements of neutron and gamma dose equivalents, respectively. Film was found to be unsatisfactory for measuring neutron doses produced by HPRR spectra in that measured dose equivalents were much lower than reference values. The TLD-100 dosimeters yielded gamma doses which were much too high indicating that this dosimeter type is generally unsuitable for use in mixed radiation fields similar to those encountered in this study without the use of large correction factors. Although the overall reported results exhibited improvement in performance relative to previous intercomparison studies, the composite measured data showed variations of more than a factor of 2 between measurements of the same exposure made by different agencies.
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| Release | : 1981 |
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Download Seventh Personnel Dosimetry Intercomparison Study Book in PDF, ePub and Kindle
The Seventh Personnel Dosimetry Intercomparison Study was conducted March 31-April 10, 1981, at the Oak Ridge National Laboratory. Dosimeters from 34 participating agencies were mounted on anthropomorphic phantoms and exposed to a range of low-level dose equivalents (1.5-15.0mSv neutron and 0.1-2.8 mSv gamma) which could be encountered during routine personnel monitoring in mixed radiation fields. The Health Physics Research Reactor, operating in the steady-state mode, served as the source of radiation for two equivalent sets of six separate exposures. Lucite and concrete shields along with the unshielded reactor provided three different neutron and gamma spectra for five of the exposures in each set. Results reported by the participating agencies showed that no single type of neutron dosimeter exhibited acceptable performance characteristics for all mixed-field environments encountered in this study. Film, TLD, and TLD-albed dosimeters were found to be inadequate for neutron dose equivalent measurements when large numbers of slow neutrons are present unless significant corrections are made to measured results. Track dosimeters indicated the least sensitivity to spectral characteristics, but did not always yield to the most accurate results. Gamma dose measurements showed that TLD-700 dosimeters produced significantly more accurate results than film dosimeters which tend to overestimate gamma doses in mixed radiation fields.
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| Total Pages | : 84 |
| Release | : 1993 |
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Download Development and Evaluation of a Neutron-gamma Mixed-field Dosimetry System Based on a Single Thermoluminescence Dosimeter Book in PDF, ePub and Kindle
A neutron-gamma mixed-field dosimetry system based on a single lithium fluoride thermoluminescence dosimeter was developed. The system's ability to perform in the mixed neutron-gamma field of the lead/bismuth irradiation facility at the Ohio State University Research Reactor was then evaluated. Such a system is needed to gather accurate dosimetry data for radiobiology experiments which are performed in the lead/bismuth facility. The system was found to be inadequate for the purpose of measuring both dose components in the irradiation facility. In that environment, the system's response to the gamma radiation is obscured by the response to neutron radiation. A sensitivity analysis was performed to estimate the system's performance under different conditions, in order to determine the condition for which the system is useful for resolving both the gamma and the neutron components of the dose.
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| Total Pages | : 2 |
| Release | : 1991 |
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Download Neutron Personnel Dosimetry Intecomparison Studies Book in PDF, ePub and Kindle
The Dosimetry Applications Research (DOSAR) Group at the Oak Ridge National Laboratory (ORNL) has conducted sixteen Neutron Personnel Dosimetry Intercomparison Studies (PDIS) since 1974. During these studies dosimeters are mailed to DOSAR, exposed to low-level (typically in the 0.3 -- 5.0 mSv range) neutron dose equivalents in a variety of mixed neutron-gamma radiation fields, and then returned to the participants for evaluation. The Health Physics Research Reactor (HPRR) was used as the primary radiation source in PDIS 1--12 and radioisotopic neutron sources at DOSAR's Radiation Calibration Laboratory (RADCAL) were mainly used, along with sources and accelerators at cooperating institutions, in PDIS 13--16. Conclusions based on 13,560 measurements made by 146 different participating organizations (102 - US) are presented.
| Author | : K. Becker |
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| Total Pages | : 39 |
| Release | : 1965 |
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Download Nuclear Track Registration in Dosimeter Glasses for Neutron Dosimetry in Mixed Radiation Fields Book in PDF, ePub and Kindle
The fission track detection in fission foil/glass combinations avoids most of the disadvantages of the conventional methods (nuclear track evaluations and activation foils) for integrating neutron measurements. These systems are insensitive to gamma radiation, temperature, climatic and chemical disturbances, easy to evaluate, have no directional dependence, an extended dose and energy range, superior accuracy, etc. The method has been investigated, using different dosimeter glasses, etching conditions, fissionable materials and neutron energies between thermal and 14 MeV. The fission track detection efficiency is 100%, the sensitivity for fissionable metals thicker than ca. 5 microns is 0.000013 tracks/neutron/barn. Simple evaluation techniques and practical applications, mainly for fast neutron personnel dosimetry, are described. (Author).
