Development of an Absolute Gas-Counting Capability for Low to Medium Activities

Journal Article · Fri Nov 01 00:00:00 EDT 2013 · Applied Radiation and Isotopes

DOI:https://doi.org/10.1016/j.apradiso.2013.03.064· OSTI ID:1331746

Williams, Richard M.; Aalseth, Craig E.; Ely, James H.; Day, Anthony R.; Hayes, James C.; Hoppe, Eric W.; LaFerriere, Brian D.; Mace, Emily K.; Merriman, Jason H.; Overman, Cory T.; Seifert, Allen

ABSTRACT Pacific Northwest National Laboratory (PNNL) is developing a capability to measure the absolute activity concentration of various gaseous radionuclides using length-compensated proportional-counting methods. This capability will enable the validation and use of low-level, gaseous radionuclide calibration standards for use in PNNL’s shallow underground laboratory. Two sets of unequal length proportional counters have been fabricated. These detector assemblies operate on a static gas-fill principle, in contrast to continuous, flow-through configurations. One set of three counters has been fabricated using ultra-low background (ULB) electroformed copper and low-background fabrication methods. Once fully operational, these ULB counters will be used in PNNL’s shallow underground counting laboratory for analysis of gases with low activity concentrations < 1 Bq/cc. A second set of four unequal length counters has been fabricated from Oxygen-Free High-Conductivity Copper (OFHC) using similar low-background cleaning and assembly methods. These OFHC counters will be operated above ground in the analysis of gases with activity concentrations in the range of 1-10 Bq/cc. A gas delivery system is being developed to actively mix the analyte gas with an appropriate amount of count-gas and uniformly deliver it to the counters with high accuracy and repeatability. A description of both detector assemblies and gas delivery system will be given along with a preliminary uncertainty analysis of a simulated 0.05 Bq/cm3 gas measurement.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1331746
• Report Number(s): PNNL-SA-89541
• Journal Information: Applied Radiation and Isotopes, Journal Name: Applied Radiation and Isotopes Vol. 81; ISSN 0969-8043
• Publisher: Elsevier
• Country of Publication: United States
• Language: English