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Book Synopsis Neutron Personnel Dosimetry Intecomparison Studies by :
Download or read book Neutron Personnel Dosimetry Intecomparison Studies written by and published by . This book was released on 1991 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Twelve Years of Neutron Personnel Dosimetry Intercomparison Studies at Oak Ridge National Laboratory by :
Download or read book Twelve Years of Neutron Personnel Dosimetry Intercomparison Studies at Oak Ridge National Laboratory written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Personnel Dosimetry Intercomparison Studies at the ORNL Health Physics Research Reactor by :
Download or read book Personnel Dosimetry Intercomparison Studies at the ORNL Health Physics Research Reactor written by and published by . This book was released on 1977 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Health Physics Research Reactor (HPRR), used unshielded, with a 12-cm-thick Lucite shield or a 13-cm-thick steel shield, provided three neutron and gamma-ray spectra for personnel dosimetry intercomparison studies. The characterisitcs of these fields, such as neutron energy spectrum, intensity, and uniformity, had been measured previously during nuclear accident dosimetry studies. Exposures were made to simulate total exposures likely to be encountered in personnel dosimetry. Neutron dose equivalents of the order of 500 mrem were produced. Dosimeters were mounted on the trunk section of water-filled phantoms, the front edges of which were located three meters from the reactor center. When shields were used they were placed at two meters. Sulfur pellets exposed at a standard location on the reactor during the intercomparison were used to calculate values of tissue kerma for neutrons at the three meter position based on previous measurements. Hurst proportional counter measurements made at the time of the exposures are in good agreement with these results. The gamma component of dose, typically of the order of a few tens of mrad, was measured with LiF thermoluminescent dosimeters (TLD's). Using the fission yield and the calculated leakage of the HPRR, the neutron fluence was calculated for each reactor run. Then the dose was calculated based on the HPRR neutron spectra and the dose conversion factors which had been calculated previously for the three spectra. The results of these personnel dosimetry intercomparison studies reveal that estimates of dose equivalent vary over a wide range. The standard deviation of the mean of participants data was typically in the range of +-30 to +-40%. It is anticipated that this type of dosimetry intercomparison study will be worthwhile on an annual basis until the problems in dosimeter response and interpretation have been identified and solved.
Book Synopsis Summary and Analysis of Neutron Measurements Conducted During the Oak Ridge Personnel Dosimetry Intercomparison Studies by :
Download or read book Summary and Analysis of Neutron Measurements Conducted During the Oak Ridge Personnel Dosimetry Intercomparison Studies written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Since 1974, neutron personnel dosimetry intercomparison studies (PDIS) have been conducted annually at the Oak Ridge National Laboratory's (ORNL) Dosimetry Applications Research Facility. During these studies, neutron dosimeters are mailed to ORNL, exposed to low-level (less than 15 mSv) dose equivalents in a variety of mixed-radiation fields produced using the Health Physics Research Reactor (HPRR), and then returned to the participants for evaluation. Beginning with the Seventh PDIS in 1981, interest and participation in the Oak Ridge intercomparisons increased significantly and consistent and documented techniques for determining reference neutron dose equivalents for the HPRR were introduced. This document presents a summary and analysis of approximately 3400 neutron dose equivalent measurements made using a variety of personnel dosimeters and reported for PDIS 7-12. 16 refs., 3 tabs.
Book Synopsis Intercomparison of High Energy Neutron Personnel Dosimeters by :
Download or read book Intercomparison of High Energy Neutron Personnel Dosimeters written by and published by . This book was released on 1993 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: An intercomparison of high-energy neutron personnel dosimeters was performed to evaluate the uniformity of the response characteristics of typical neutron dosimeters presently in use at US Department of Energy (DOE) accelerator facilities. It was necessary to perform an intercomparison because there are no national or international standards for high-energy neutron dosimetry. The testing that is presently under way for the Department of Energy Laboratory Accreditation Program (DOELAP) is limited to the use of neutron sources that range in energy from about 1 keV to 2 MeV. Therefore, the high-energy neutron dosimeters presently in use at DOE accelerator facilities are not being tested effectively. This intercomparison employed neutrons produced by the 9Be(p, n)9B interaction at the University of Washington cyclotron, using 50-MeV protons. The resulting neutron energy spectrum extended to a maximum of approximately 50-MeV, with a mean energy of about 20-MeV. Intercomparison results for currently used dosimeters, including Nuclear Type A (NTA) film, thermoluminescent dosimeter (TLD)-albedo, and track-etch dosimeters (TEDs), indicated a wide variation in response to identical doses of high-energy neutrons. Results of this study will be discussed along with a description of plans for future work.
Book Synopsis Third Personnel Dosimetry Intercomparison Study by :
Download or read book Third Personnel Dosimetry Intercomparison Study written by and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The third Personnel Dosimetery Intercomparison Study was held at the Oak Ridge National Laboratory Dosimetry Applications Research Facility during March 15--16, 1977. The Health Physics Research Reactor (HPRR), used unshielded, with a 12-cm-thick Lucite shield or a 13-cm-thick steel shield, provided three neutron and gamma-ray spectra. The characteristics of these fields such as neutron energy spectra, intensity, and uniformity had been measured previously during nuclear accident dosimetry studies. Exposures were made to simulate total exposures likely to be encountered in personnel dosimetry. Neutron dose equivalents of the order of 500 millirem were produced by controlling the reactor power level and exposure time. Dosimeters were mounted on the trunk section of water-filled phantoms, the front edges of which were located 3 m from the reactor center. When shields were used they were placed at 2 m from the core. Sulfur pellets exposed at a standard location on the reactor during the intercomparison were used to calculate values of tissue kerma for neutrons at the 3-m position based on previous measurements. Using the fission yield and the calculated leakage of the HPRR, the neutron fluence was calculated for each reactor run. Then the dose was calculated based on the HPRR neutron spectra and the dose conversion factors, which had been calculated previously for the three spectra. The results of these personnel dosimetry intercomparison studies reveal that estimates of dose equivalent vary over a wide range. The standard deviation of the mean of participants data was in the range of 25 to 50%.
Book Synopsis Sixth Personnel Dosimetry Intercomparison Study by :
Download or read book Sixth Personnel Dosimetry Intercomparison Study written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Performance Characteristics of Neutron Personnel Dosemeters Used in the Oak Ridge Intercomparison Studies by :
Download or read book Performance Characteristics of Neutron Personnel Dosemeters Used in the Oak Ridge Intercomparison Studies written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To provide an opportunity for dosimetrists to test and calibrate their neutron personnel monitoring systems, the staff of the Dosimetry Applications Research Facility at the Oak Ridge National Laboratory (ORNL) has conducted personnel dosimetry intercomparison studies (PDIS) periodically since 1974. During these studies, neutron dosemeters are mailed to ORNL, exposed to low-level (less than 15 mSv) dose equivalents in a variety of mixed-radiation fields produced using the Health Physics Research Reactor (HPRR), and then returned to the participants for evaluation. Beginning with the Seventh PDIS in 1981, interest and participation in the Oak Ridge intercomparisons increased significantly and consistent and documented methods for determining reference neutron dose equivalents for the HPRR were introduced. This paper presents a summary and analysis of about 3450 neutron dose equivalent measurements reported for PDIS 7 through 12 (1981-1986) with particular emphasis on low dose equivalent sensitivity, accuracy and precision, and performance relative to accreditation standards for the basic types of personnel dosimetry systems. (16 refs., 3 tabs.
Book Synopsis Personnel-dosimetry Intercomparison Studies at the Oak Ridge National Laboratory by :
Download or read book Personnel-dosimetry Intercomparison Studies at the Oak Ridge National Laboratory written by and published by . This book was released on 1982 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Since 1974, seven annual personnel dosimetry intercomparison studies have been conducted at the Oak Ridge National Laboratory using the Health Physics Reactor. These studies have produced more than 2000 measurements by 72 participating organizations of neutron and gamma dose equivalents between 0.1 to 15.0 mSv in six mixed radiation fields. The relative performance of three basic types of personnel neutron dosimeters (nuclear emulsion film, thermoluminescent, and track-etch) and two basic types of gamma dosimeters (film and thermoluminescent) was assessed based on experimental results obtained during the seven intercomparisons.
Book Synopsis Seventh Personnel Dosimetry Intercomparison Study by :
Download or read book Seventh Personnel Dosimetry Intercomparison Study written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Neutron Dosimetry written by John W. Baum and published by . This book was released on 1955 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Neutron Personnel Dosimetry by : Robert B. Schwartz
Download or read book Neutron Personnel Dosimetry written by Robert B. Schwartz and published by . This book was released on 1987 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fourth Personnel Dosimetry Intercomparison Study by :
Download or read book Fourth Personnel Dosimetry Intercomparison Study written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The fourth Personnel Dosimetry Intercomparison Study was held at the Oak Ridge National Laboratory's Dosimetry Applications Research Facility during March 15-23, 1978. The Health Physics Research Reactor (HPRR) used unshielded, with a 12-cm-thick Lucite shield, a 20-cm-thick concrete shield, or a 5-cm-thick steel and 15-cm-thick concrete shield, and provided four neutron and gamma-ray spectra. Then the dose was calculated based on the HPRR neutron spectra and dose conversion factors which had been determined previously for the four spectra. The results of these personnel dosimetry intercomparison studies reveal that estimates of dose equivalent vary over a wide range. The standard deviation of the mean of participants data for gamma measurements was in the range of 29 to 43%; for neutrons it was 57 to 188%. (PCS).
Book Synopsis 1987 Neutron and Gamma Personnel Dosimeter Intercomparison Study Using a D2O-moderated 252Cf Source by :
Download or read book 1987 Neutron and Gamma Personnel Dosimeter Intercomparison Study Using a D2O-moderated 252Cf Source written by and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The thirteenth Personnel Dosimetry Intercomparison Study (i.e., PDIS 13) was conducted during April 1987 as a joint effort by Oak Ridge National Laboratory's (ORNL) Dosimetry Applications Research Group and the Southwest Radiation Calibration Center at the University of Arkansas. A total of 48 organizations (34 from the US and 14 from abroad) participated in PDIS 13. Participants submitted a total of 1,113 neutron and gamma dosimeters for this mixed field study. The dosimeters were transferred by mail and were handled by experimental personnel at ORNL and the University of Arkansas. The type of neutron dosimeter and the percentage of participants submitting that type are as follows: TLD-albedo (49%), direct interaction TLD (31%), CR-39 (17%), film (3%). The type of gamma dosimeter and the percentage of participants submitting that type are as follows: Li2B4O--, alone or in combination with CaSO4, (69%), 7LiF (28%), natural LiF (3%). Radiation exposures in PDIS 13 were limited to 0.5 and 1.5 mSv from 252Cf moderated by 15-cm of D2O. Traditional exposures using the Health Physics Research Reactor (HPRR) were not possible due to the fact that all reactors at ORNL, including the HPRR, were shutdown by order of the Department of Energy at the time the intercomparison was performed. Planned exposures using a 238PuBe source were negated by a faulty timing mechanism. Based on accuracy and precision, direct interaction TLD dosimeters exhibited the best performance in PDIS 13 neutron measurements. They were followed, in order of best performance, by CR-39, TLD albedo, and film. The Li2B4O-- type TLD dosimeters exhibited the best performance in PDIS 13 gamma measurements. They were followed by natural LiF, 7LiF, and film. 12 refs., 1 fig., 5 tabs.
Book Synopsis Nonparametric Analysis of an International Neutron Dosimetry Intercomparison by :
Download or read book Nonparametric Analysis of an International Neutron Dosimetry Intercomparison written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An International Neutron Dosimetry Intercomparison (INDI) was carried out in 1973 at the Radiological Research Accelerator Facility (RRAF) of Brookhaven National Laboratory under the sponsorship of the International Commission on Radiation Units and Measurements (ICRU). Fourteen groups of scientists, from six countries, performed measurements to determine the separate neutron and photon (x- and gamma-ray) tissue kermas in free air for four energies of monoenergetic neutrons, 15.1, 5.5, 2.1, and 0.67 MeV, and for a source of fission neutrons, 252Cf. For the two highest energies measurements were also made to determine the separate absorbed doses in tissue of neutrons and of photons at three depths in a large water phantom. Nonparametric analyses of the calculated relative responses of the tissue equivalent ionization chambers showed significant concordance. (CH).
Book Synopsis 1989 Neutron and Gamma Personnel Dosimetry Intercomparison Study Using RADCAL (Radiation Calibration Laboratory) Sources by :
Download or read book 1989 Neutron and Gamma Personnel Dosimetry Intercomparison Study Using RADCAL (Radiation Calibration Laboratory) Sources written by and published by . This book was released on 1990 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt: The fourteenth Personnel Dosimetry Intercomparison Study (i.e., PDIS 14) was conducted during May 1-5, 1989. A total of 48 organizations (33 from the US and 15 from abroad) participated in PDIS 14. Participants submitted by mail a total of 1,302 neutron and gamma dosimeters for this mixed field study. The type of neutron dosimeter and the percentage of participants submitting that type are as follows: TLD-albedo (40%), direct interaction TLD (22%), track (20%), film (7%), combination (7%), and bubble detectors (4%). The type of gamma dosimeter and the percentage of participants submitting that type are as follows: TLD (84%) and film (16%). Radiation sources used in the six PDIS 14 exposures included 252Cf moderated by 15-cm D2O, 252Cf moderated by 15-cm polyethylene (gamma-enhanced with 137Cs), and 238PuBe. Neutron dose equivalents ranged from 0.44--2.63 mSv and gamma doses ranged from 0. 01-1.85 mSv. One 252Cf(D2O) exposure was performed at a 60° angle of incidence (most performance tests are at perpendicular incidence). The average neutron dosimeter response for this exposure was 70% of that at normal incidence. The average gamma dosimeter response was 96% of that at normal incidence. A total of 70% of individual reported neutron dosimeter measurements were within {plus minus}50% of reference values. If the 0.01 mSv data are omitted, approximately 90% of the individual reported gamma measurements were within {plus minus}50% of reference values. 33 refs., 9 figs., 27 tabs.
Book Synopsis Fifth Personnel Dosimetry Intercomparison Study by :
Download or read book Fifth Personnel Dosimetry Intercomparison Study written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The fifth Personnel Dosimetry Intercomparison Study (PDIS) was conducted at the Oak Ridge National Laboratory's (ORNL) Dosimetry Applications Research (DOSAR) facility on March 20-22, 1979. This study is the latest PDIS in the continuing series started at the DOSAR facility in 1974. The PDIS is a three day study, typically in March, where personnel dosimeters are mailed to the DOSAR facility, exposed to a range of low-level neutron radiation doses (1 to 15 mSv or equivalently, 100 to 1500 mrem) and neutron-to-gamma ratios (1:1-10:1) using the Health Physics Research Reactor (HPRR) as the radiation source, and returned to the participants for evaluation. This report is a summary and analysis of the results reported by the various participants. The participants are able to intercompare their results with those of others who made dose measurements under identical experimental conditions.
