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Title: Modeling and Qualification of a Modified Emission Unit for Radioactive Air Emissions Stack Sampling Compliance

A planned laboratory space and exhaust system modification to the Pacific Northwest National Laboratory Material Science and Technology Building indicated a new evaluation of the mixing at the air sampling system location would be required for compliance to ANSI/HPS N13.1-2011. The modified exhaust system would add a third fan thereby increasing the overall exhaust rate out the stack thus voiding the previous mixing study. Prior to modifying the radioactive air emissions exhaust system, a three-dimensional computational fluid dynamics computer model was used to evaluate the mixing at the sampling system location. Modeling of the new original three-fan system indicated that not all mixing criteria could be met. A second modeling effort was conducted with the addition of an air blender downstream of the confluence of the three fans which then showed satisfactory mixing results. The final installation included an air blender, and the exhaust system underwent full-scale tests to verify velocity, cyclonic flow, gas, and particulate uniformity. The modeling results and those of the full-scale tests show agreement between each of the evaluated criteria. The use of a computational fluid dynamics code was an effective aid in the design process and allowed the sampling system to remain in its originalmore » location while still meeting the requirements for sampling at a well-mixed location.« less
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Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0017-9078
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Health Physics; Journal Volume: 111; Journal Issue: 5
Health Physics Society
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
Country of Publication:
United States
atmospheric emissions; air monitoring; environmental monitoring; ANSI; and computational fluid dynamics