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Title: Aerial Measuring System Sensor Modeling

Abstract

This project deals with the modeling the Aerial Measuring System (AMS) fixed-wing and rotary-wing sensor systems, which are critical U.S. Department of Energy's National Nuclear Security Administration (NNSA) Consequence Management assets. The fixed-wing system is critical in detecting lost or stolen radiography or medical sources, or mixed fission products as from a commercial power plant release at high flying altitudes. The helicopter is typically used at lower altitudes to determine ground contamination, such as in measuring americium from a plutonium ground dispersal during a cleanup. Since the sensitivity of these instruments as a function of altitude is crucial in estimating detection limits of various ground contaminations and necessary count times, a characterization of their sensitivity as a function of altitude and energy is needed. Experimental data at altitude as well as laboratory benchmarks is important to insure that the strong effects of air attenuation are modeled correctly. The modeling presented here is the first attempt at such a characterization of the equipment for flying altitudes. The sodium iodide (NaI) sensors utilized with these systems were characterized using the Monte Carlo N-Particle code (MCNP) developed at Los Alamos National Laboratory. For the fixed wing system, calculations modeled the spectral response formore » the 3-element NaI detector pod and High-Purity Germanium (HPGe) detector, in the relevant energy range of 50 keV to 3 MeV. NaI detector responses were simulated for both point and distributed surface sources as a function of gamma energy and flying altitude. For point sources, photopeak efficiencies were calculated for a zero radial distance and an offset equal to the altitude. For distributed sources approximating an infinite plane, gross count efficiencies were calculated and normalized to a uniform surface deposition of 1 {micro}Ci/m{sup 2}. The helicopter calculations modeled the transport of americium-241 ({sup 241}Am) as this is the ''marker'' isotope utilized by the system for Pu detection. The helicopter sensor array consists of 2 six-element NaI detector pods, and the NaI pod detector response was simulated for a distributed surface source of {sup 241}Am as a function of altitude.« less

Authors:
Publication Date:
Research Org.:
Bechtel Nevada Corporation (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
794083
Report Number(s):
DOE/NV/11718-709
TRN: US0201105
DOE Contract Number:  
AC-8096NV11718
Resource Type:
Conference
Resource Relation:
Conference: Unattended Radiation Sensor Systems for Remote Application Conference, Washington, DC (US), 04/15/2002--04/17/2002; Other Information: PBD: 1 Apr 2002
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; AMERICIUM 241; NAI DETECTORS; POINT SOURCES; NUCLEAR POWER PLANTS; SPECTRAL RESPONSE; AERIAL MONITORING; REMOTE SENSING; RADIATION MONITORING; NUCLEAR MATERIALS DIVERSION; NUCLEAR MATERIALS POSSESSION; HIGH-PURITY GE DETECTORS; GAMMA DETECTION; SENSITIVITY

Citation Formats

R. S. Detwiler. Aerial Measuring System Sensor Modeling. United States: N. p., 2002. Web.
R. S. Detwiler. Aerial Measuring System Sensor Modeling. United States.
R. S. Detwiler. Mon . "Aerial Measuring System Sensor Modeling". United States. https://www.osti.gov/servlets/purl/794083.
@article{osti_794083,
title = {Aerial Measuring System Sensor Modeling},
author = {R. S. Detwiler},
abstractNote = {This project deals with the modeling the Aerial Measuring System (AMS) fixed-wing and rotary-wing sensor systems, which are critical U.S. Department of Energy's National Nuclear Security Administration (NNSA) Consequence Management assets. The fixed-wing system is critical in detecting lost or stolen radiography or medical sources, or mixed fission products as from a commercial power plant release at high flying altitudes. The helicopter is typically used at lower altitudes to determine ground contamination, such as in measuring americium from a plutonium ground dispersal during a cleanup. Since the sensitivity of these instruments as a function of altitude is crucial in estimating detection limits of various ground contaminations and necessary count times, a characterization of their sensitivity as a function of altitude and energy is needed. Experimental data at altitude as well as laboratory benchmarks is important to insure that the strong effects of air attenuation are modeled correctly. The modeling presented here is the first attempt at such a characterization of the equipment for flying altitudes. The sodium iodide (NaI) sensors utilized with these systems were characterized using the Monte Carlo N-Particle code (MCNP) developed at Los Alamos National Laboratory. For the fixed wing system, calculations modeled the spectral response for the 3-element NaI detector pod and High-Purity Germanium (HPGe) detector, in the relevant energy range of 50 keV to 3 MeV. NaI detector responses were simulated for both point and distributed surface sources as a function of gamma energy and flying altitude. For point sources, photopeak efficiencies were calculated for a zero radial distance and an offset equal to the altitude. For distributed sources approximating an infinite plane, gross count efficiencies were calculated and normalized to a uniform surface deposition of 1 {micro}Ci/m{sup 2}. The helicopter calculations modeled the transport of americium-241 ({sup 241}Am) as this is the ''marker'' isotope utilized by the system for Pu detection. The helicopter sensor array consists of 2 six-element NaI detector pods, and the NaI pod detector response was simulated for a distributed surface source of {sup 241}Am as a function of altitude.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2002},
month = {4}
}

Conference:
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