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New technique to improve the accuracy of albedo neutron dosimeter evaluations

Description: The calibration factor for albedo neutron dosimeters varies greatly depending upon the energy of the neutrons in the exposure. Calibration results obtained over an eight-year period at each Lawrence Livermore National Laboratory facility where neutron exposure may occur were reviewed. A stronger relationship than expected was found between the ratio of the readings of the 9-in. to 3-in. spheres and the percent thermal. Readings from personnel and albedo badges were reviewed. The readings were consistent with the use of a calibration factor for the albedo dosimeter which varies with changes in the ratio of the personnel and albedo dosimeter TLD readings. 2 references, 6 figures. (ACR)
Date: January 1, 1984
Creator: Hankins, D.E.
Partner: UNT Libraries Government Documents Department

Los Alamos personnel and area criticality dosimeter systems

Description: Fissionable materials are handled and processed at the Los Alamos National Laboratory. Although the probability of a nuclear criticality accident is very remote, it must be considered. Los Alamos maintains a broad spectrum of dose assessment capabilities. This report describes the methods employed for personnel neutron, area neutron, and photon dose evaluations with passive dosimetry systems.
Date: June 1, 1981
Creator: Vasilik, D.G. & Martin, R.W.
Partner: UNT Libraries Government Documents Department

Personnel neutron dosimetry at Department of Energy facilities

Description: This study assesses the state of personnel neutron dosimetry at DOE facilities. A survey of the personnel dosimetry systems in use at major DOE facilities was conducted, a literature search was made to determine recent advances in neutron dosimetry, and several dosimetry experts were interviewed. It was concluded that personnel neutron dosimeters do not meet current needs and that serious problems exist now and will increase in the future if neutron quality factors are increased and/or dose limits are lowered.
Date: August 1, 1980
Creator: Brackenbush, L.W.; Endres, G.W.R.; Selby, J.M. & Vallario, E.J.
Partner: UNT Libraries Government Documents Department

Beta-dosimetry studies at LLNL

Description: This paper summarizes three beta-dosimetry studies made recently at the Lawrence Livermore National Laboratory. The first study was to determine the beta-gamma exposure rates at the Los Alamos Godiva IV Critical Assembly. The beta spectra from the assembly were evaluated using absorption curves and the beta-gamma dose-rate ratios were determined at various distances from the assembly. A comparison was made of the doses determined using two types of TLD personnel dosimeters and a film badge. The readings of an Eberline RO-7 instrument and the dose rates determined by TLDs were compared. Shielding provided by various metals, gloves, and clothing were measured. The second study was to determine the beta energy response of the Eberline RO-7 instrument based on measurements made with the PTB beta sources. This study required additional calibration points for the PTB sources which were made using extrapolation chamber measurements. The third study resulted in two techniques to determine the beta energy (E/sub max/) from the readings of this-window portable survey instruments. Both techniques are based on the readings obtained using aluminium filters. One technique is for field application, requires one filter, and provides a quick estimate of the beta energy in three energy groups: < 0.5 MeV, 0.5 MeV to 1.5 MeV and > 1.5 MeV. The second technique is more complex requiring measurements with two or three filters, but gives the beta energy and the approximate shape of the beta spectrum. 9 references, 6 figures.
Date: January 1, 1983
Creator: Hankins, D.E.
Partner: UNT Libraries Government Documents Department

The determination of the penetrating radiation dose at Hanford

Description: Most of the thermoluminescent dosimeters (TLDs) and other devices that have been used to measure environmental radiation on the Hanford Site have measured natural background levels of radiation. Measurements of offsite environmental radiation near the boundary of the Hanford Site have often indicated higher doses than onsite measurements have. However, the converse has been found when radiation measurements from the cities and communities of southeastern Washington were compared with onsite measurements. The historical trends described for environmental TLD data have been better defined in this study by compiling the TLD data for selected locations over a 6-year period (1983 to 1988). The ongoing Hanford Environmental Surveillance Program also provides radionuclide concentrations in soil based on samples collected by technicians at Pacific Northwest Laboratory (PNL) and sent to a commercial laboratory for analyses. As part of the study described in this report, a portable gamma spectroscopy system was used in the field to identify concentrations of gamma-emitting radionuclides in the soil at various locations on the Hanford Site and in the surrounding area. This work began in 1986. Supplemental radiation measurements were made with a microprocessor-based survey meter and large NaI detector. 20 refs., 4 figs., 3 tabs.
Date: September 1, 1989
Creator: Rathbun, L.A.
Partner: UNT Libraries Government Documents Department

Neutron dose equivalents at the Advanced Light Source: Calculation using the MORSE code vs estimated values

Description: The Advanced Light Source (ALS) complex at the Lawrence Berkeley Laboratory (LBL) is surrounded by a mezzanine and auxiliary buildings. An important radiological problem is the neutron dose equivalent in nearby occupied areas and at the LBL site boundary. Both the direct and air-scattered (skyshine) components of the neutron dose equivalents are evaluated using the neutron transport code MORSE. The shielding was designed using an empirical method based on data scaled from a 1977 SLAC experiment and on a compilation of experimental and theoretical material relevant to shielding of electron accelerators. From the MORSE calculation, the total occupational dose equivalent rate in the center of the ALS mezzanine was found to be less than 1 mSv (100 mrem) per shift year (2000-hr), and the total environmental dose equivalent rate at the ALS boundary, 125 m from the storage-ring center, was found to be about 302 {mu}Sv (30 mrem) per year. A comparison of the dose equivalents shows that the calculated MORSE-code values agree well with those estimated by the empirical method. That is, dose equivalents obtained by the empirical methods are of the same order of magnitude as the corresponding MORSE values. 7 refs., 7 figs., 2 tabs.
Date: February 1, 1991
Creator: Sun, Rai-Ko S.
Partner: UNT Libraries Government Documents Department

Biological and clinical dosimetry. Progress report, October 1, 1979-September 30, 1980

Description: Several major dosimetric intercomparisons were carried out during the last year. At the National Institute of Radiological Sciences, Chiba-shi and the University of Tokyo, Tokyo, Japan, calorimetric and ionimetric intercomparisons of dose were performed. Similar measurements were also carried out at the Lawrence Berkeley Laboratory, Los Alamos, and Harvard. The measurements of the thermal defect for A-150 plastic were completed and an average value of (4.1 +- 0.3)% was found. Preliminary measurements using a cryogenic calorimeter were carried out at Lawrence Livermore National Laboratory. The first measurement of the event size distribution for 20-MeV neutrons were carried out at Ohio University and an interesting difference between the measurement and theoretical calculations was found. The measured fraction of events due to alpha particles was found to be significantly lower than the fraction predicted by the calculation of Caswell and Coyne.
Date: September 30, 1980
Creator: Laughlin, J.S. & McDonald, J.C.
Partner: UNT Libraries Government Documents Department

Neutron dose and energy spectra measurements at Savannah River Plant

Description: Because some workers have a high potential for significant neutron exposure, the Savannah River Plant (SRP) contracted with Pacific Northwest Laboratory (PNL) to verify the accuracy of neutron dosimetry at the plant. Energy spectrum and neutron dose measurements were made at the SRP calibrations laboratory and at several other locations. The energy spectra measurements were made using multisphere or Bonner sphere spectrometers,/sup 3/He spectrometers, and NE-213 liquid scintillator spectrometers. Neutron dose equivalent determinations were made using these instruments and others specifically designed to determine dose equivalent, such as the tissue equivalent proportional counter (TEPC). Survey instruments, such as the Eberline PNR-4, and the thermoluminescent dosimeter (TLD)-albedo and track etch dosimeters (TEDs) were also used. The TEPC, subjectively judged to provide the most accurate estimation of true dose equivalent, was used as the reference for comparison with other devices. 29 refs., 43 figs., 13 tabs.
Date: August 1, 1987
Creator: Brackenbush, L.W.; Soldat, K.L.; Haggard, D.L.; Faust, L.G. & Tomeraasen, P.L.
Partner: UNT Libraries Government Documents Department

A suitability study of the fission product phantom and the bottle manikin absorption phantom for calibration of in vivo bioassay equipment for the DOELAP accreditation testing program

Description: Pacific Northwest laboratory (PNL) conducted an intercomparison study of the Fission Product phantom and the bottle manikin absorption (BOMAB) phantom for the US Department of Energy (DOE) to determine the consistency of calibration response of the two phantoms and their suitability for certification and use under a planned bioassay laboratory accreditation program. The study was initiated to determine calibration factors for both types of phantoms and to evaluate the suitability of their use in DOE Laboratory Accreditation Program (DOELAP) round-robin testing. The BOMAB was found to be more appropriate for the DOELAP testing program. 9 refs., 9 figs., 9 tabs.
Date: August 1, 1991
Creator: Olsen, P.C. & Lynch, T.P.
Partner: UNT Libraries Government Documents Department

Albedo-neutron dosimetry studies at Lawrence Livermore Laboratory

Description: This report summarized studies performed since the last workshop meeting. The studies have been divided into four sections: (1) the relative response of Hankins-type albedo-neutron dosimeters made of cadmium and boron; (2) the effect of distance from the body on the response of albedo-neutron dosimeters; (3) the use of the ratio of the top to bottom TLDs to determine the calibration factor for albedo-neutron dosimeters; and (4) neutron survey at a power reactor and at a neutron radiography facility.
Date: November 1, 1978
Creator: Hankins, D.E.
Partner: UNT Libraries Government Documents Department

Pacific Northwest Laboratory annual report for 1988 to the DOE Office of Energy Research: Part 4, Physical sciences

Description: This document contains brief descriptions of various research programs in the physical science. Topics include Chernobyl Information Management, Supercritical Fluids, Laser Spectroscopy, DNA Adducts, Dosimetry, Biophysics, and Genetic Damage. (TEM)
Date: March 1, 1989
Creator: Touburen, L.H.
Partner: UNT Libraries Government Documents Department

Pacific Northwest Laboratory Annual Report for 1987 to the DOE Office of Energy Research: Part 4, Physical Sciences

Description: This 1987 annual report from Pacific Northwest Laboratory describes research in environment, health, and safety conducted during fiscal year 1987. The report again consists of five parts, each in a separate volume. Part 4 includes those programs funded under the title ''Physical and Technological Research.'' The Field Task Program Studies reports in this document are grouped by budget category and each section is introduced by an abstract that indicates the Field Task Proposal/Agreement reported in that section.
Date: June 1, 1988
Creator: Toburen, L.H.
Partner: UNT Libraries Government Documents Department