| Minimum detectable concentration as a function of gamma walkover survey technique. | |
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MedLine Citation:
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PMID: 22249469 Owner: NLM Status: In-Data-Review |
Abstract/OtherAbstract:
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ABSTRACT:: Gamma walkover surveys are often performed by swinging the radiation detector (e.g., a 2-inch by 2-inch sodium iodide) in a serpentine pattern at a near constant height above the ground surface. The objective is to survey an approximate 1-m swath with 100% coverage producing an equal probability of detecting contamination at any point along the swing. In reality, however, the detector height will vary slightly along the swing path, and in some cases the detector may follow a pendulum-like motion significantly reducing the detector response and increasing the minimum detectable concentration. This paper quantifies relative detector responses for fixed and variable height swing patterns and demonstrates negative impacts on the minimum detectable concentration. Minimum detectable concentrations are calculated for multiple contaminated surface areas (0.1, 1.0, 3, 10, and 30 m), multiple contaminants (Co, Cs, Am, and Ra), and two minimum heights (5 and 10 cm). Exposure rate estimates used in minimum detectable concentration calculations are produced using MicroShield™ v.7.02 (Grove Software, Inc., 4925 Boonsboro Road #257, Lynchberg, VA 24503) and MDCs are calculated as outlined in NUREG-1575. Results confirm a pendulum-like detector motion can significantly increase MDCs relative to a low flat trajectory, especially for small areas of elevated activity-up to a 47% difference is observed under worst-modeled conditions. |
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Authors:
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David A King; Nickolas Altic; Colt Greer |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Health physics Volume: 102 Suppl 1 ISSN: 1538-5159 ISO Abbreviation: Health Phys Publication Date: 2012 Feb |
Date Detail:
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Created Date: 2012-01-17 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 2985093R Medline TA: Health Phys Country: United States |
Other Details:
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Languages: eng Pagination: S22-7 Citation Subset: IM |
Affiliation:
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* Oak Ridge Associated Universities, Independent Environmental Assessment and Verification, 1299 Bethel Valley Road, Oak Ridge, TN; † Ecology Services, Inc., 9135 Guilford Road, Suite 200, Columbia, MD 21046. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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