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Title: Minimum detectable activity and false alarm rate relationships for alpha continuous air monitors

Abstract

The U.S. Department of Energy rule for Occupational Radiation Protection (10 CFR Part 835, December 1993) and the DOE Radiological Control Manual (the RCM) (DOE/EH-0256T, Rev. 1, April 1994) require the use of continuous air monitors (CAMs) in normally occupied areas where an individual is likely to be exposed to a concentration of airborne radioactivity exceeding the derived air concentration (DAC) or where there is a need to alert potentially exposed individuals to unexpected increases in airborne radioactivity levels. The DAC is the airborne concentration that equals the annual limit on intake divided by the volume of air breathed by an average worker for a working year of 2000 h (assuming a breathing volume of 2400 m{sup 3}). It is equivalent to the airborne concentration to which a worker could be exposed for an entire working year (2000 h) without exceeding the allowable annual limit on intake. The rule and the RCM further require that real-time air monitors have an alarm capability and sufficient sensitivity to alert potentially exposed individuals that immediate action is necessary in order to minimize or terminate inhalation exposures. The RCM also recommends that real-time air monitors should be capable of measuring 1 DAC when averagedmore » over 8 h (8 DAC-h) under laboratory conditions. In response to these recommendations, we are developing procedures for determining the basic sensitivity of alpha CAMs under laboratory conditions and for documenting practical alarm set points for routine use of CAMs under a range of radon and thoron concentrations.« less

Authors:
;
Publication Date:
Research Org.:
Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States). Inhalation Toxicology Research Inst.
OSTI Identifier:
54787
Report Number(s):
ITRI-144
ON: DE95007526; TRN: 95:012732
DOE Contract Number:
AC04-76EV01013
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Nov 1994; Related Information: Is Part Of Inhalation Toxicology Research Institute annual report, October 1, 1993--September 30, 1994; Belinsky, S.A.; Hoover, M.D.; Bradley, P.L. [eds.]; PB: 211 p.
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 56 BIOLOGY AND MEDICINE, APPLIED STUDIES; 29 ENERGY PLANNING AND POLICY; RADIATION MONITORS; ALARM SYSTEMS; SENSITIVITY; RADIOACTIVE AEROSOLS; MAXIMUM INHALATION QUANTITY; ALPHA DECAY RADIOISOTOPES; AEROSOL MONITORING; PROGRESS REPORT

Citation Formats

Hoover, M.D., and Newton, G.J.. Minimum detectable activity and false alarm rate relationships for alpha continuous air monitors. United States: N. p., 1994. Web.
Hoover, M.D., & Newton, G.J.. Minimum detectable activity and false alarm rate relationships for alpha continuous air monitors. United States.
Hoover, M.D., and Newton, G.J.. 1994. "Minimum detectable activity and false alarm rate relationships for alpha continuous air monitors". United States. doi:.
@article{osti_54787,
title = {Minimum detectable activity and false alarm rate relationships for alpha continuous air monitors},
author = {Hoover, M.D. and Newton, G.J.},
abstractNote = {The U.S. Department of Energy rule for Occupational Radiation Protection (10 CFR Part 835, December 1993) and the DOE Radiological Control Manual (the RCM) (DOE/EH-0256T, Rev. 1, April 1994) require the use of continuous air monitors (CAMs) in normally occupied areas where an individual is likely to be exposed to a concentration of airborne radioactivity exceeding the derived air concentration (DAC) or where there is a need to alert potentially exposed individuals to unexpected increases in airborne radioactivity levels. The DAC is the airborne concentration that equals the annual limit on intake divided by the volume of air breathed by an average worker for a working year of 2000 h (assuming a breathing volume of 2400 m{sup 3}). It is equivalent to the airborne concentration to which a worker could be exposed for an entire working year (2000 h) without exceeding the allowable annual limit on intake. The rule and the RCM further require that real-time air monitors have an alarm capability and sufficient sensitivity to alert potentially exposed individuals that immediate action is necessary in order to minimize or terminate inhalation exposures. The RCM also recommends that real-time air monitors should be capable of measuring 1 DAC when averaged over 8 h (8 DAC-h) under laboratory conditions. In response to these recommendations, we are developing procedures for determining the basic sensitivity of alpha CAMs under laboratory conditions and for documenting practical alarm set points for routine use of CAMs under a range of radon and thoron concentrations.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1994,
month =
}

Technical Report:
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  • The U.S. Department of Energy rule for Occupational Radiation Protection and the DOE Radiological Control Manual (the RCM) (DOE/EH-0256T, Rev 1, April 1994) require the use of continuous air monitors (CAMs) in normally occupied areas there an individual is likely to be exposed to a concentration of airborne radioactivity exceeding the derived air concentration (DAC) or where there is need to alert potentially exposed individuals to unexpected increases in airborne radioactivity levels. The DAC is the airborne concentration that equals the annual limit on intake divided by the volume of air breathed by an average worker for a working yearmore » of 2,000 h (assuming a breathing volume of 2,400 m{sup 3}). It is equivalent to the airborne concentration to which a worker could be exposed for an entire year (2,000 h) without exceeding the annual limit on intake. The rule and the RCM further require that real-time air monitors have an alarm capability and sufficient sensitivity to alert potentially exposed individuals that immediate action is necessary in order to minimize or terminate inhalation exposures. The RCM also recommends that real-time air monitors should be capable of measuring 1 DAC when averaged over 8 h (8 DAC) under laboratory conditions. This report was prepared jointly with actual data from the CAMs in use at the WIPP by ITRI, WID, and EEG and provides an evaluation of minimum detectable activity (MDA) or concentration and false alarm rate relationships. The methodology used in this report is adapted from Inhalation Toxicology Research Institute Annual Report for 1993-1994, ITRI-144, pp 18-22, December 1994.« less
  • Lawrence Livermore National Laboratory maintains an in vivo measurement program designed to identify and evaluate the activity of radionuclides deposited in the body. Two types of systems are primarily used for the routine monitoring of radiation workers, the lung counting system and the scanning bed whole body counting system. The lung counting system is comprised of two Canberra ACTII detector sets. Each ACTII set contains two planar germanium detectors with carbon composite end windows optimized to measure low energy photon emitting radionuclides. The ACTII detectors are placed on the upper torso over the lungs for the direct measurement of internallymore » deposited radionuclides in the lungs that emit low energy photons. A correction for the thickness of the chest wall is applied to the efficiency. Because the thickness of the chest wall is a key factor in the measurement of low energy photon emitting radionuclides in the lung, the minimum detectable activity is a function of the chest wall thickness. The scanning bed whole body counting system is comprised of a thin air mattress on top of a carbon fiber bed that slowly scans over four high purity germanium detectors. The scanning system is designed to minimize variations in detected activity due to radionuclide distribution in the body. The scanning bed detection system is typically used for the measurement of internally deposited radionuclides that emit photons above 100 to 200 keV. MDAs have been generated for radionuclides that provide energies above 80 keV since the lowest calibration energy for the system is approximately 86 keV. The following charts and table provide best determination of minimum detectable activity using human subjects as controls for the background contributions. A wide variety of radionuclides are used throughout the laboratory and the following pages represent several of the radionuclides that have been encountered at the Whole Body and Spectroscopy Laboratories within Hazards Control.« less
  • The rate at which a mine detection system falsely identifies man-made or natural clutter objects as mines is referred to as the system's false alarm rate (FAR). Generally expressed as a rate per unit area or time, the FAR is one of the primary metrics used to gauge system performance. In this report, an overview is given of statistical methods appropriate for the analysis of data relating to FAR. Techniques are presented for determining a suitable size for the clutter collection area, for summarizing the performance of a single sensor, and for comparing different sensors. For readers requiring more thoroughmore » coverage of the topics discussed, references to the statistical literature are provided. A companion report addresses statistical issues related to the estimation of mine detection probabilities.« less
  • Eberline Alpha 6 and Alpha 6A continuous air monitors (CAMs) were tested against the performance criteria of the International Electrotechnical Commission standard 761-6, ``Equipment for Continuously Monitoring Radioactivity in Gaseous Effluents, Part 6: Specific Requirements for Transuranic Aerosol Effluent Monitors``, and against ANSI N42.17B, ``Performance Specification Health Physics Instrumentation--Occupational Airborne Radioactivity Monitoring Instrumentation``. The performance criteria require the CAM`s response to a radioactive source to remain within a tolerance while the CAM is exposed to an external influence such as temperature, electromagnetic fields, or ionizing radiations. The CAMs complied within specified tolerances with a majority of the performance specifications. Themore » most significant problems with CAM performance were noted during exposures to external nonionizing radiation fields (radio frequency fields). At numerous frequencies, the CAMs did not respond to radioactive material in the filter holder. At other frequencies and in some orientations, the CAMs overresponded by orders of magnitude. In addition to sensitivity to external nonionizing radiation fields, the CAMs exhibited sensitivity to electrostatic discharges.« less