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[en] An effective radiological effluent and surveillance program is critical for a nuclear facility to (1) comply with applicable regulations, (2) assess the potential impacts of operations to the environment and public, and (3) inform stakeholders and members of the public of any impacts. Radiological environmental monitoring includes three program elements - effluent monitoring, environmental surveillance, and dose assessments. The key to an effective program is defining the baseline and objectives based on regulatory requirements, identification of the critical exposure pathways, determining the spatial and temporal boundaries for the monitoring, and defining the reporting and action levels. Another key to an effective program is through continuous improvement by transforming the program based on operational facility changes and responding to technology advancements in the field of environmental monitoring. The history of the Savannah River Site's (SRS) environmental monitoring program is an example of an effective program that has transitioned, changed, and improved over the years based on the site missions and operations. From the beginning of five production reactors and two chemical separations facilities to the current Site missions of Environmental Stewardship, National Security, and Clean Energy, the SRS environmental monitoring program has evolved. SRS has a unique ecological environment with the Site area covering 80,300 hectares, five major streams that lead to the Savannah River, various water bodies, and varied meteorological conditions. Airborne and liquid pathways to human exposure are complex and it is necessary to use a graded approach when monitoring these pathways. The SRS environmental monitoring program is designed and effective in ensuring and verifying that there is a minimal exposure impact on the public and the environment from Site operations. (authors)
[en] During the operational history of Savannah River Site, many different radionuclides have been released from site facilities. However, as shown in this analysis, only a relatively small number of the released radionuclides have been significant contributors to doses to the offsite public. This report is an update to the 2011 analysis, Critical Radionuclide and Pathway Analysis for the Savannah River Site. SRS-based Performance Assessments for E-Area, Saltstone, F-Tank Farm, H-Tank Farm, and a Comprehensive SRS Composite Analysis have been completed. The critical radionuclides and pathways identified in those extensive reports are also detailed and included in this analysis.
[en] The U.S. Environmental Protection Agency (EPA) requested an external, independent verification study of their updated Preliminary Remediation Goals for Radionuclides (PRG) electronic calculator. The calculator provides PRGs for radionuclides that are used as a screening tool at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and Resource Conservation and Recovery Act (RCRA) sites. These risk-based PRGs establish concentration limits under specific exposure scenarios. The purpose of this verification study is to determine that the calculator has no inherit numerical problems with obtaining solutions as well as to ensure that the equations are programmed correctly. There are 167 equations used in the calculator. To verify the calculator, all equations for each of seven receptor types (resident, construction worker, outdoor and indoor worker, recreator, farmer, and composite worker) were hand calculated using the default parameters. The same four radionuclides (Am-241, Co-60, H-3, and Pu-238) were used for each calculation for consistency throughout.
[en] MAXINE is an EXCEL© spreadsheet, which is used to estimate dose to individuals for routine and accidental atmospheric releases of radioactive materials. MAXINE does not contain an atmospheric dispersion model, but rather doses are estimated using air and ground concentrations as input. Minimal input is required to run the program and site specific parameters are used when possible. Complete code description, verification of models, and user’s manual have been included.
[en] The contaminated ground surface at Savannah River Site (SRS) is a result of the decades of work that has been performed maintaining the country's nuclear stockpile and performing research and development on nuclear materials. The volatilization of radionuclides during wildfire results in airborne particles that are dispersed within the smoke plume and may result in doses to downwind firefighters and the public. To better understand the risk that these smoke plumes present, we have characterized four regions at SRS in terms of their fuel characteristics and radiological contamination on the ground. Combined with general meteorological conditions describing typical and extreme burn conditions, we have simulated potential fires in these regions and predicted the potential radiological dose that could be received by firefighting personnel and the public surrounding the SRS. In all cases, the predicted cumulative dose was a small percent of the US Department of Energy regulatory limit (0.25 mSv). These predictions were conservative and assumed that firefighters would be exposed for the duration of their shift and the public would be exposed for the entire day over the duration of the burn. Realistically, firefighters routinely rotate off the firefront during their shift and the public would likely remain indoors much of the day. However, we show that even under worst-case conditions the regulatory limits are not exceeded. In conclusion, we can infer that the risks associated with wildfires would not be expected to cause cumulative doses above the level of concern to either responding personnel or the offsite public.
[en] The Savannah River National Laboratory (SRNL) with the assistance of Georgia Regents University, completed a comparison of the U.S. Environmental Protection Agency's (EPA) environmental dosimetry code CAP88 PC V3.0 with the recently developed V4.0. CAP88 is a set of computer programs and databases used for estimation of dose and risk from radionuclide emissions to air. At the U.S. Department of Energy's Savannah River Site, CAP88 is used by SRNL for determining compliance with EPA's National Emission Standards for Hazardous Air Pollutants (40 CFR 61, Subpart H) regulations. Using standardized input parameters, individual runs were conducted for each radionuclide within its corresponding database. Some radioactive decay constants, human usage parameters, and dose coefficients changed between the two versions, directly causing a proportional change in the total effective "1"3"7Cs, "3H, "1"2"9I, "2"3"9Pu, and "9"0Sr) is provided. In general, the total effective doses will decrease for alpha/beta emitters because of reduced inhalation and ingestion rates in V4.0. However, for gamma emitters, such as "6"0Co and "1"3"7Cs, the total effective doses will increase because of changes EPA made in the external ground shine calculations
[en] Highlights: • The distribution of radionuclides in contaminated and uncontaminated plots along a riparian system was characterized. • 137Cs, 226Ra, and 40K were the radionuclides with the highest activity in the soil and litter along the streams. • 90Sr was the only radionuclide with a higher radioactivity in the litter than in the soil. • Correlation between soil and litter was observed for 137Cs in contaminated plots and U isotopes in uncontaminated plots. • No apparent spatial trend in deposition density of the radionuclides along the streams was observed. - Abstract: The aim of this study is to comprehensively investigate radionuclide concentrations in surface soil and un-decayed vegetative litter along four stream systems (i.e. Fourmile Branch, Lower Three Runs, Pen Branch, and Steel Creek) at the Savannah River Site (SRS), Aiken, South Carolina. Soil and litter samples from systematically spaced 12 pairs (contaminated or uncontaminated) of plots along the four streams were analyzed for 16 distinct radionuclide activities. Lower radionuclide concentrations were observed in soil and litter samples collected along Pen Branch compared to the other 3 streams. The anthropogenic radionuclide with the highest activity was 137Cs in soil (10.6–916.9 Bq/kg) and litter (8.0–222.3 Bq/kg), while the naturally occurring radionuclides possessing the highest concentration in the samples were 40K (33.5–153.7 Bq/kg and 23.1–56.0 Bq/kg in soil and litter respectively) and 226Ra (55.6–159.9 Bq/kg and 30.2–101.8 Bq/kg in soil and litter respectively). A significant difference (p 241Am, 137Cs, 238Pu, 239Pu, and 226Ra in both contaminated and non-contaminated samples. 137Cs and uranium isotopes had the highest litter-to-soil correlation in contaminated (rho = 0.70) and uncontaminated plots (rho = 0.31–0.41), respectively. 90Sr was the only radionuclide with higher radioactive concentrations in litter (12.65–37.56 Bq/kg) compared to soil (1.61–4.79 Bq/kg). The result indicates that 1) historical discharges of anthropogenic 137Cs was the most important contributor of radiation contamination in the riparian environment at SRS, 2) 90Sr was the only radionuclide with higher concentration in litter than in soil, and 3) no apparent pattern in deposition density in soil or litter along downstream was observed for the radionuclides measured in this study.
[en] Firefighters responding to wildland fires where surface litter and vegetation contain radiological contamination will receive a radiological dose by inhaling resuspended radioactive material in the smoke. This may increase their lifetime risk of contracting certain types of cancer. Using published data, we modelled hypothetical radionuclide emissions, dispersion and dose for 70"t"h and 97"t"h percentile environmental conditions and for average and high fuel loads at the Savannah River Site. We predicted downwind concentration and potential dose to firefighters for radionuclides of interest ("1"3"7Cs, "2"3"8Pu, "9"0Sr and "2"1"0Po). Predicted concentrations exceeded dose guidelines in the base case scenario emissions of 1.0 x10"7 Bq ha"-"1 for "2"3"8Pu at 70"t"h percentile environmental conditions and average fuel load levels for both 4- and 14-h shifts. Under 97"t"h percentile environmental conditions and high fuel loads, dose guidelines were exceeded for several reported cases for "9"0Sr, "2"3"8Pu and "2"1"0Po. The potential for exceeding dose guidelines was mitigated by including plume rise (>2 m s"-"1) or moving a small distance from the fire owing to large concentration gradients near the edge of the fire. In conclusion, this approach can quickly estimate potential dose from airborne radionuclides in wildland fire and assist decision-making to reduce firefighter exposure
[en] Standard procedures for the measurement of tritium in water samples often require distillation of an appropriate sample aliquot. This distillation process may result in a fractionation of tritiated water and regular light water due to the vapor pressure isotope effect, introducing either a bias or an additional contribution to the total tritium measurement uncertainty. The current study investigates the relative change in vapor pressure isotope effect in the course of the distillation process, distinguishing it from and extending previously published measurements. The separation factor as a quantitative measure of the vapor pressure isotope effect is found to assume values of 1.04 ± 0.036, 1.05 ± 0.026, and 1.07 ± 0.038, depending on the vigor of the boiling process during distillation of the sample. A lower heat setting in the experimental setup, and therefore a less vigorous boiling process, results in a larger value for the separation factor. For a tritium measurement in water samples where the first 5 mL are discarded, the tritium concentration could be underestimated by 4–7%. - Highlights: • Tritium measurements in environmental water samples. • Distilled samples. • Vapor pressure isotope effect. • Depending on boiling mode. • Potential underestimate of tritium activity concentration of 4–7%