TAM-D - Special Session: Environmental / Radon Section Orange A 08:30 - 12:00
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| Chair(s): James Reese, Phil Egidi
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TAM-D.1
08:30 Measurements of Alpha and Beta Radiation from Uncontaminated Surfaces of Common Building Materials CA Bullock*, Los Alamos National Laboratory
; JJ Whicker, Los Alamos National Laboratory; MJ Chastenet, Los Alamos National Laboratory; M Mcnaughton, Los Alamos National Laboratory
Abstract: Federal regulation requires the measurement of radioactivity located in or on potentially-contaminated items or materials prior to public release. Surface radioactivity must be at or below radioactivity limits that are protective of the public. These limits are low enough that contributions to radioactive emissions from naturally occurring radioactive materials (NORM) in the building materials must be considered. In uncontaminated materials, measurements commonly reflect NORM content inside construction materials in addition to radon decay products that have collected on surfaces. Therefore, it is important to quantify typical background NORM count rates to accurately determine the fraction of radioactivity added to building materials by radiological operations. In Department of Energy facilities, and specifically Los Alamos National Laboratory (LANL), there are numerous buildings scheduled for Decontamination and Decommissioning (D&D). While many of these buildings never hosted radiological operations, some did and have the potential for residual radioactive contamination on the building surfaces. Numerous regulations and requirements protect public safety by preventing excessive exposure to potentially contaminated materials (e.g., 10 CFR 835, DOE 458.1,).
Specifically, Department of Energy Order 458.1, Radiation Protection of the Public and the Environment (DOE 2013), provides guidance for evaluating material releases and establishes a dose limit of 1 mrem/yr (10 μSv/y) for the release of personal property to the public. This order also affirms the surface contamination limits found in the predecessor order DOE Order 5400.5 (DOE 1990) as authorized limits for public release of materials. Additionally, the American National Standards Institute (ANSI) and the Health Physics Society have jointly produced guidance for material release that relies upon a dose limit to the public of 1 mrem/y (10 μSv/y) from a material’s radionuclide content (ANSI N. 13.12 (2013)). In addition to the federal requirements in DOE Orders, the state of New Mexico requires that waste materials sent to commercial landfills contain no measureable LANL-derived radioactive materials. Thus, debris can be buried in commercial landfills only if measurements indicate radioactivity levels are indistinguishable from background. If any anthropogenic contamination is detected, the debris must be buried as radioactive waste. Thus, measuring the NORM contribution to the radioactivity measurements of materials to be released is critical.
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TAM-D.2
08:55 Statistical Analysis for Indistinguishable from Background Unrestricted Release of Property Using Visual Basic M Chastenet*, Los Alamos National Lab
; C Bullock, Los Alamos National Lab; JJ Whicker, Los Alamos National Lab
Abstract: Radiation survey data are used to determine if property meets the criteria for unrestricted release to the public under Department of Energy Order 458.1, Radiation Protection for the Public and Environment. A sampling and data analysis plan is developed to meet the measurement quality objectives under the Multi-Agency Radiation Survey and Assessment of Materials and Equipment. Statistical analysis of the survey data is performed to determine if the measurements are indistinguishable from background and can be released. Visual Basic code was developed to analyze survey data by performing the statistical analyses and testing for statistical differences in the measurements compared to uncontaminated reference material. The code reduces human error and improves efficiency.
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TAM-D.3
09:50 Long-Term Assessment of Critical Radionuclides and Associated Environmental Media at the Savannah River Site GT Jannik*, Savannah River National Laboratory
; MH Paller, Savannah River National Laboratory; RA Baker, Savannah River National Laboratory; TP Eddy, Savannah River Nuclear Solutions
Abstract: During the operational history of the Savannah River Site (SRS), many different radionuclides have been released from site facilities. However, only a relatively small number of the released radionuclides have been significant contributors to doses and risks to the public. At SRS dose and risk assessments indicate tritium oxide in air and surface water, and Cs-137 in fish and deer have been, and continue to be, the critical radionuclides and pathways. In this assessment, statistical analyses of the long-term trends of tritium oxide in atmospheric and surface water releases and Cs-137 concentrations in fish and deer are provided. Correlations also are provided with 1) operational changes and improvements, 2) geopolitical events (Cold War cessation), and 3) recent environmental remediation projects and decommissioning of excess facilities. For example, environmental remediation of the F- and H-Area Seepage Basins and the Solid Waste Disposal Facility have resulted in a measurable impact on the tritium oxide flux to the onsite Fourmile Branch stream. Airborne releases of tritium oxide have been greatly affected by operational improvements and the end of the Cold War in 1991. However, the effects of SRS environmental remediation activities and ongoing tritium operations on tritium concentrations in the environment are measurable and documented in this assessment. Controlled hunts of deer and feral hogs are conducted at SRS for approximately six weeks each year. Before any harvested animal is released to a hunter, SRS personnel perform a field analysis for Cs-137 concentrations to ensure the hunter’s dose does not exceed the SRS administrative game limit of 0.22 millisievert (22 mrem). However, most of the Cs-137 found in SRS onsite deer is not from site operations but is from nuclear weapons testing fallout from the 1950’s and early 1960’s. This legacy source term is trended in the SRS deer, and an assessment of the “effective” half-life of Cs-137 in deer (including the physical decay half-life and the environmental dispersion half-life) is provided. The “creek mouth” fisherman is the next most critical pathway at SRS. On an annual basis, three species of fish (panfish, catfish, and bass) are sampled from the mouths of the five SRS streams. Three composites of up to five fish of each species are analyzed from each sampling location. Long-term trending of the Cs-137 concentrations in fish and the subsequent doses from consumption of SRS fish is provided.
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TAM-D.4
10:15 Uptake of Radionuclides by Plants from Soils at Uranium Mine Impacted Sites JT Hargraves*, Oregon State University
; KA Higley, Oregon State University
Abstract: Throughout the duration of the 1950s, uranium mining was prolific throughout the Colorado Plateau. While much of surface mining activity has subsided, there remain large areas with elevated concentrations of uranium and progeny in soils. Cost effective and environmentally benign remediation strategies are desirable. Techniques such as phytoremediation, or its alternative phytostabilization, are environmentally passive techniques that may provide options for cleanup. These methodologies have the potential to mitigate soils affected by previous mining activities by removing or isolating contaminants of concern. As part of an ongoing effort to evaluate the remediation capabilities of native plant species, collection and characterization of both soil and plant species across a contaminant concentration gradient were conducted. Samples were obtained using a statistically defined stratified sampling technique, followed by radium and uranium isotopes content analysis. Analyses were performed through progeny ingrowth measured by gamma spectrometry and Instrumental Neutron Activation Analysis (INAA), respectively. Similarly, native plants were evaluated for potential phytoremediation capability.
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TAM-D.5
10:40 International Radiation Protection and Waste Management Guidance for NORM/TENORM Sites P Egidi*, US EPA
Abstract: Management and disposition of TENORM is often not subject to the authority of the Atomic Energy Act (AEA). Therefore, these activities may not be conducted under a radioactive materials license and therefore have less stringent requirements for environmental monitoring as well as occupational radiation protection programs. Most NORM/TENORM sites that are being addressed have some regulatory requirements for monitoring, training, record keeping, health and safety under other statutes and regulations, including state authorities. There are numerous guidance documents from national and international bodies that outline the standard of care for these activities. Recent publications from the International Atomic Energy Agency will be discussed along with similar domestic guidance documents.
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