VTH-A - Special Session: Rad Air NESHAPs 10:00 - 13:10
NOTE: ALL VIRTUAL SESSIONS WILL TAKE PLACE DURING PACIFIC STANDARD TIME.
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VTH-A.1
10:00 U.S. Environmental Protection Agency Update on the Radionuclide NESHAPs JP Walsh*, U.S. EPA
; JH Rustick, U.S. EPA
Abstract: Under the Clean Air Act, the U.S. Environmental Protection Agency (EPA) has regulatory authority over several categories of sources that have the potential to emit radionuclides into the ambient environment through the air pathway. The National Emissions Standards for Hazardous Air Pollutants (NESHAPs) for radionuclides include eight subparts of 40 CFR Part 61, which apply to various government and industrial sectors, including underground uranium mines, Department of Energy facilities, other federal facilities, elemental phosphorus plants, phosphogypsum stacks, and uranium mill tailings piles. The radionuclide NESHAPs are implemented by the EPA’s Office of Radiation and Indoor Air, EPA Regional offices, and several delegated State governments. This presentation includes a summary of each relevant subpart of the regulation, including its current status, and any significant recent activities such as rule modifications, guidance, requests by regulated parties, and Agency approvals. The primary focus of the presentation is on activities that have taken place in the past year, and brief case studies are presented for those developments that either have a broad effect on the regulated community or are of particular interest to the health physics community.
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VTH-A.2
10:20 DOE Subpart H Report A Williamson, DOE-HQ
; SF Snyder*, PNNL Richland
Abstract: Each U.S. Department of Energy site with radionuclide emissions to air is required to determine compliance with the 40 CFR 61, Subpart H, NESHAP standard, annually. A summary of DOE Site calendar year 2019 radioactive emissions and compliance status is presented. 2019 results relative to other recent years are presented, as well.
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VTH-A.3
10:40 U.S. Environmental Protection Agency Update on Compliance Codes BK Littleton*, U.S. Environmental Protection Agency
; DO Stuenkel, U.S. Environmental Protection Agency; RP Wood, Trinity Engineering Associates
Abstract: The U.S. Environmental Protection Agency (EPA) maintains several computer codes used to demonstrate compliance with public dose limits set by 40 CFR 61, National Emission Standards for Hazardous Air Pollutants (NESHAPs). These include CAP-88 PC, COMPLY, and COMPLY-R. On March 5, 2020, EPA published a Notice of Availability for CAP88-PC Version 4.1 in the Federal Register (85 FR 12917). Version 4.1 updates the dose and risk conversion factors from those included in DCFPAK 2.2 to those in DCFPAK 3.02; implements a new installer technology that enhances compatibility with Windows 10 (and future Windows updates); and makes some minor changes to the user interface. The CAP88 User’s Manual has been updated, and a quick start guide has been developed. Both CAP88-PC Versions 4.0 and 4.1 can be downloaded from the EPA website, and either version can be used to demonstrate compliance with Subpart H. At the same time as the release of CAP88-PC Version 4.1, EPA released a beta version of STARGET, a stand-alone code to convert meteorological data from the stability array (STAR) file format to the "wind file" format required by the code. Like the past effort to update COMPLY, EPA is currently updating COMPLY-R to run under the 32 and 64-bit Windows operating systems. Plans for future updates to all three codes are currently under consideration.
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11:00 BREAK
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VTH-A.4
11:30 Use of AERMOD as an Alternative Model for COMPLY-R DO Stuenkel*, U.S. Environmental Protection Agency
; BK Littleton, U.S. Environmental Protection Agency; JP Walsh, U.S. Environmental Protection Agency
Abstract: To demonstrate compliance with 40 CFR 61, National Emission Standards for Hazardous Air Pollutants (NESHAPs), Subpart B, an owner or operator of an active underground uranium mine must demonstrate that emissions of radon-222 to the ambient air shall not exceed those amounts that would cause any member of the public to receive in any year an effective dose equivalent of 0.1 millisieverts (10 mrem) per year to the maximally exposed individual. EPA’s COMPLY-R computer code is approved for calculating effective dose equivalents and allows the mine owner or operator to demonstrate compliance with a minimum of required inputs. The disadvantage to this approach is that when there more than several active mines in the mine complex, the code can result in the need to make and combine results from multiple runs or overly conservative dose estimates. In 2020, EPA received a request from an owner/operator of an active underground uranium mine to use AERMOD as an alternative equivalent model to COMPLY-R, as allowed in 40 CFR 61.23 for demonstrating compliance for its 2019 emissions. The AERMOD Modeling System is a steady-state plume model that incorporates air dispersion based on planetary boundary layer turbulence structure and scaling concepts, including treatment of both surface and elevated sources, and both simple and complex terrain. After reviewing the applicability of as an alternative to COMPLY-R, EPA approved the request. As part of its review, EPA identified similarities and differences between AERMOD and COMPLY-R, as well as required inputs and settings to use AERMOD as an alternative model to COMPLY-R. The major results of this review are discussed in this presentation.
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VTH-A.5
11:50 Collective Analysis Using Mass Loading to Determine Sample Filter Self-Absorption JM Barnett*, Pacific Northwest National Laboratory
; HZ Edwards, Pacific Northwest National Laboratory
Abstract: As filter media becomes loaded with particulate matter, there is potential for alpha particulate losses due to self-absorption by mass loading. Relationships between air sample filter mass loading and the correlated analytical self-absorption factor were developed using data from six published research studies. The mass loading consists of particulate dust, radioactive particulates, and filter material. Historically, mass loading of about 3.7 mg cm^-2 presumed 100% self-absorption, while more recently, the 100% losses have been determined to be in the 10 mg cm^-2 range. Based on the data from published studies, the different methods for relating percent loss due to self-absorption to mass loading included linear, polynomial, exponential, and trinomial derived functions, using both a forced zero intercept and non-forced zero option. The trinomial function showed the best results. Once the sample filter mass loading is known, the trinomial function can be applied to estimate the self-absorption factor. When applied to normal operating conditions at the building stacks monitored at the Pacific Northwest National Laboratory for an average sample filter mass loading of 0.09 mg cm^-2 and a range from 0 to 0.24 mg cm^-2, the estimated trinomial function nominal self-absorption losses are about 5% or less. ANSI/HPS N13.1-2011 guidelines indicate a correction factor should be used when the penetration of radioactive material into the collection media or self-absorption of radiation by the material collected would reduce the count rate by more than 5%. Although the Pacific Northwest National Laboratory has historically used a self-absorption correction factor of 15% (i.e., 0.85), the results here show it may be reasonable to no longer apply a correction factor to the stack samples. Nevertheless, it would remain conservative to assign the self-absorption correction factor at the 5% threshold (i.e., 0.95) for general uses and in cases of heavy mass loading to calculate the factor.
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VTH-A.6
12:10 Discussion
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