TPM-D - Special Session - Rad NESHAPS Orange A 14:30 - 17:15
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| Chair(s): Matthew Barnett, Dave Fuehne
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TPM-D.1
14:30 U.S. Environmental Protection Agency Update on the Radionuclide NESHAPs JP Walsh*, U.S. EPA
Abstract: The U.S. Environmental Protection Agency (EPA) has regulatory oversight under the Clean Air Act of several source categories with the potential to emit radionuclides into the airborne environment. The National Emissions Standards for Hazardous Air Pollutants (NESHAP) for radionuclides include eight subparts of 40 CFR Part 61, which apply to Department of Energy facilities, Naval shipyards, elemental phosphorus plants, phosphogypsum disposal, and uranium mill tailings. These regulations are implemented by EPA headquarters, EPA Regional offices, and several delegated State governments. A summary of the past year’s relevant activities by the EPA is presented. Major topic areas include updates to EPA’s internal procedural documents, outreach to and collaboration with Regional and State partners, and work performed in response to requests made by regulated parties.
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TPM-D.2
14:45 U.S. Environmental Protection Agency Update on Compliance Codes BK Littleton*, U.S. EPA
; R Wood, Trinity Engineering Associates; D Stuenkel, Trinity Engineering Associates
Abstract: The U.S. Environmental Protection Agency (EPA) maintains computer codes used to demonstrate compliance with public dose limits set by its radionuclide NESHAPs. New updates to the CAP-88 PC v4.1 dose model will be discussed, as well as efforts to review and update the COMPLY and COMPLY-R codes.
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TPM-D.3
15:00 Resuspension and Redistribution of Plutonium and Americium in the WIPP Environment AL Ward*, US Department of Energy
; P Thakur, Carlsbad Environmental Monitoring and Research Center
Abstract: At the U.S. Department of Energy (DOE) deep geological repository of defense-related transuranic (TRU) waste, located at the Waste Isolation Pilot Plant (WIPP) near Carlsbad in southeastern New Mexico, the radionuclides of greatest concern are 239+240Pu and 241Am. These radionuclides account for more than 99% of the total radioactivity slated for disposal. Isotopes of plutonium and americium are also present in environmental samples at trace levels with activity ratios of ~0.37 for 241Am/239+240Pu, and ~0.024 for 238Pu/239+240Pu in the mid-latitudes, indicative of a global fallout origin. In this context, the spatiotemporal variation, and transport behavior of these radionuclides in the WIPP environment, are important for identifying any releases during operations, should they occur, and for evaluating post-closure performance. Historical aerosol data from WIPP ambient air sampling show frequent detections of 239+240Pu and 241Am, and less frequent detections of 238Pu. Concentrations of 239+240Pu and 241Am typically peak in the March to June timeframe, coinciding with the period of highest winds in an area prone to wind erosion. These data suggest that saltation and suspension of soil and sediment, previously contaminated by weapons testing fallout, is the primary source of plutonium and americium in ambient air samples at WIPP, and responsible for the higher frequency of detection during high-wind events. During the 2014 accidental release, aerosol concentrations of 241Am briefly increased downwind of the exhaust shaft, changing the 241Am/239+240Pu ratio from ~0.37 to ~10, but have since returned to background. There is currently no evidence that WIPP operations is a source of environmental contamination that can be considered significant by any health-based standard.
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TPM-D.4
15:45 On Sampling The Background Indoor Particulate Resuspension Factor SA Marshall*, Worcester Polytechnic Institute
; DC Medich, Worcester Polytechnic Institute; C Potter, Sandia National Laboratories
Abstract: Airborne radionuclides deliver a dose of radiation when inhaled or ingested proportional to exposure to air activity. Predicting the resuspended air concentration following a surface deposit is difficult given the number of complicating factors present which influence the resuspension mechanism, especially outdoors. The currently accepted model used by federal agencies for such predictions, the 2011 Maxwell-Anspaugh semi-empirical resuspension factor, has been shown to provide limited applicability due to its dataset spanning numerous environments, particulate sources, and nuclide species. This has motivated a recent effort to develop a catenary compartment model which would directly interact with internal biokinetic inhalation models and enable the calculation of a resuspension rate constant.
An in-house resuspension chamber allows the experimenter to probe different air sampling times and techniques to quantify resuspension of particulates. In this study, micron-sized Europium oxide powder particulates are carefully deposited atop a concrete substrate, then air is sampled at heights of 1 and 0.25 meters. Air sampler filters are then analyzed using neutron activation analysis with delayed gamma spectroscopy. All results indicate substantially lower resuspension rates, in agreement with the proposed catenary model. Additionally, lowering the sampler head from 1 to 0.25 meters significantly enhances the collection of particulates, suggesting a sensitive height distribution of particulates. Current research involves adjusting sampling time to reduce the possibility of over-sampling particulates in order to verify background resuspension dynamics.
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TPM-D.5
16:00 DOE Subpart H Report SF Snyder*, Pacific Northwest National Laboratory, Richland
; D Favret, Department of Energy, Washington, D.C.
Abstract: Each U.S. Department of Energy site with radioactive air emissions is required to determine compliance with the 40 CFR 61, Subpart H, NESHAP standard, annually. A summary of DOE Site calendar year 2017 radioactive emissions and compliance status is presented. CY2017 results relative to other recent years are presented, as well.
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TPM-D.0
16:15 Rad NESHAPS Roundtable Q&A
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