151 research outputs found
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New Meteorlogical Data for Ventsar XL
Every five years Savannah River National Laboratory (SRNL) generates an updated meteorological database to facilitate dosimetric calculations of accident and routine release scenarios for onsite and offsite populations. This information becomes the input of various environmental dosimetry codes run by the Environmental Dosimetry Group (EDG) at SRNL. The three most recent databases prior to the current one were completed for the time periods 1987-1991, 1992-1996, and 1997-2001. The current database covers the period 2002-2006. This study represents a portion of a larger study to compare the meteorological data among these four five-year periods and focuses on updating VENTSAR XL{copyright} for the current meteorological database. The updated meteorological data are also applied in other dosimetry models approved for risk and dose assessment at Savannah River Site (SRS). VENTSAR XL{copyright} is a Gaussian Plume model that includes building effects and plume rise. The typical input involves the location of the release, building dimensions, distance to the building, release height, vent diameter, vent gas temperature, gas molecular weight, ambient air temperature, breathing rate, meteorological conditions, radionuclides and their amount released. The output is easily converted into tables and graphs for further analysis and shows the concentrations and pathway doses for each of the incremental downwind distances. VENTSAR XL{copyright} has been used at SRS to investigate building effects such as reactor cooling towers in support of safety analyses. VENTSAR XL{copyright} has also been applied to Good Engineering Practice (GEP) stack height evaluations for various projects at SRS. In accordance with the Clean Air Act Amendments of 1977, GEP must be used in determining the height of any stack that will be used to disperse routine emissions. With respect to stack heights, the GEP height is 'the height necessary to ensure that emissions from the stack do not result in excessive concentrations of any air pollutant in the immediate vicinity of the source as a result of atmospheric downwash, eddies and wakes which may be created by the source itself, nearby structures or nearby terrain obstacles.' The EPA has set specific criteria to determine if a stack is of the acceptable height. These criteria have been used to determine a GEP stack height for several emission assessments at SRS. The EPA documents contain detailed information on how the height of a stack is determined. The general rule for stack height determination is to make the stack at least 2 1/2 times the height of nearby buildings. This estimated height can be increased or decreased based on other factors such as plume rise, downwash, and building wake effects
Norovirus epidemiology in community and health care settings and association with patient age, denmark
Norovirus (NoV) is a major cause of gastroenteritis. NoV genotype II.4 (GII.4) is the predominant genotype in health care settings but the reason for this finding is unknown. Stool samples containing isolates with a known NoV genotype from 2,109 patients in Denmark (patients consulting a general practitioner or outpatient clinic, inpatients, and patients from foodborne outbreaks) were used to determine genotype distribution in relation to age and setting. NoV GII.4 was more prevalent among inpatients than among patients in community settings or those who became infected during foodborne outbreaks. In community and health care settings, we found an association between infection with GII.4 and increasing age. Norovirus GII.4 predominated in patients ≥ 60 years of age and in health care settings. A larger proportion of children than adults were infected with NoV GII.3 or GII.P21. Susceptibility to NoV infection might depend on patient age and infecting NoV genotype. Cohort studies are warranted to test this hypothesis
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ASSESSMENT OF 90SR AND 137CS PENETRATION INTO REINFORCED CONCRETE (EXTENT OF 'DEEPENING') UNDER NATURAL ATMOSPHERIC CONDITIONS
When assessing the feasibility of remediation following the detonation of a radiological dispersion device or improvised nuclear device in a large city, several issues should be considered including the levels and characteristics of the radioactive contamination, the availability of resources required for decontamination, and the planned future use of the city's structures and buildings. Currently, little is known about radionuclide penetration into construction materials in an urban environment. Knowledge in this area would be useful when considering costs of a thorough decontamination of buildings, artificial structures, and roads in an affected urban environment. Pripyat, a city substantially contaminated by the Chernobyl Nuclear Power Plant accident in April 1986, may provide some answers. The main objective of this study was to assess the depth of {sup 90}Sr and {sup 137}Cs penetration into reinforced concrete structures in a highly contaminated urban environment under natural weather conditions. Thirteen reinforced concrete core samples were obtained from external surfaces of a contaminated building in Pripyat. The concrete cores were drilled to obtain sample layers of 0-5, 5-10, 10-15, 15-20, 20-30, 30-40, and 40-50 mm. Both {sup 90}Sr and {sup 137}Cs were detected in the entire 0-50 mm profile of the reinforced cores sampled. In most of the cores, over 90% of the total {sup 137}Cs inventory and 70% of the total {sup 90}Sr inventory was found in the first 0-5 mm layer of the reinforced concrete. {sup 90}Sr had penetrated markedly deeper into the reinforced concrete structures than {sup 137}Cs
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SAMPLING AND ANALYSIS PROTOCOLS
Radiological sampling and analyses are performed to collect data for a variety of specific reasons covering a wide range of projects. These activities include: Effluent monitoring; Environmental surveillance; Emergency response; Routine ambient monitoring; Background assessments; Nuclear license termination; Remediation; Deactivation and decommissioning (D&D); and Waste management. In this chapter, effluent monitoring and environmental surveillance programs at nuclear operating facilities and radiological sampling and analysis plans for remediation and D&D activities will be discussed
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VERTICAL MIGRATION OF RADIONUCLIDES IN THE VICINITY OF THE CHERNOBYL CONFINEMENT SHELTER
Studies on vertical migration of Chernobyl-origin radionuclides in the 5-km zone of the Chernobyl Nuclear Power Plant (ChNPP) in the area of the Red Forest experimental site were completed. Measurements were made by gamma spectrometric methods using high purity germanium (HPGe) detectors with beryllium windows. Alpha-emitting isotopes of plutonium were determined by the measurement of the x-rays from their uranium progeny. The presence of {sup 60}Co, {sup 134,137}Cs, {sup 154,155}Eu, and {sup 241}Am in all soil layers down to a depth of 30 cm was observed. The presence of {sup 137}Cs and {sup 241}Am were noted in the area containing automorphous soils to a depth of 60 cm. In addition, the upper soil layers at the test site were found to contain {sup 243}Am and {sup 243}Cm. Over the past ten years, the {sup 241}Am/{sup 137}Cs ratio in soil at the experimental site has increased by a factor of 3.4, nearly twice as much as would be predicted based solely on radioactive decay. This may be due to 'fresh' fallout emanating from the ChNPP Confinement Shelter
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ASSESSMENT OF THE RADIONUCLIDE COMPOSITION OF "HOT PARTICLES" SAMPLED IN THE CHERNOBYL NUCLEAR POWER PLANT FOURTH REACTOR UNIT
Fuel-containing materials sampled from within the Chernobyl Nuclear Power Plant (ChNPP) 4th Reactor Unit Confinement Shelter were spectroscopically studied for gamma and alpha content. Isotopic ratios for cesium, europium, plutonium, americium, and curium were identified and the fuel burnup in these samples was determined. A systematic deviation in the burnup values based on the cesium isotopes, in comparison with other radionuclides, was observed. The conducted studies were the first ever performed to demonstrate the presence of significant quantities of {sup 242}Cm and {sup 243}Cm. It was determined that there was a systematic underestimation of activities of transuranic radionuclides in fuel samples from inside of the ChNPP Confinement Shelter, starting from {sup 241}Am (and going higher), in comparison with the theoretical calculations
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LADTAP-PROB: A PROBABILISTIC MODEL TO ASSESS RADIOLOGICAL CONSEQUENCES FROM LIQUID RADIOACTIVE RELEASES
The potential radiological consequences to humans resulting from aqueous releases at the Savannah River Site (SRS) have usually been assessed using the computer code LADTAP or deterministic variations of this code. The advancement of LADTAP over the years included LADTAP II (a computer program that still resides on the mainframe at SRS) [1], LADTAP XL{copyright} (Microsoft Excel{reg_sign} Spreadsheet) [2], and other versions specific to SRS areas such as [3]. The spreadsheet variations of LADTAP contain two worksheets: LADTAP and IRRIDOSE. The LADTAP worksheet estimates dose for environmental pathways including ingestion of water and fish and external exposure resulting from recreational activities. IRRIDOSE estimates potential dose to individuals from irrigation of food crops with contaminated water. A new version of this deterministic methodology, LADTAP-PROB, was developed at Savannah River National Laboratory (SRNL) to (1) consider the complete range of the model parameter values (not just maximum or mean values), (2) determine the influences of parameter uncertainties within the LADTAP methodology, to perform a sensitivity analysis of all model parameters (to identify the input parameters to which model results are most sensitive), and (3) probabilistically assess radiological consequences from contaminated water. This study presents the methodology applied in LADTAP-PROB
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THE DOE OFFICE OF ENVIRONMENTAL MANAGEMENT INTERNATIONAL COOPERATIVE PROGRAM: OVERVIEW OF TECHNICAL TASKS AND RESULTS
The DOE Office of Environmental Management (DOE-EM) Office of Engineering and Technology is responsible for implementing EM's International Cooperative Program. Over the past 15 years, collaborative work has been conducted through this program with researchers in Russia, Ukraine, France, United Kingdom and Republic of Korea. Currently, work is being conducted with researchers in Russia and Ukraine. Efforts aimed at evaluating and advancing technologies to support U.S. high-level waste (HLW) vitrification initiatives are being conducted in collaboration with Russian researchers. Work at Khlopin Radium Institute (KRI) is targeted at improving the throughput of current vitrification processes by increasing melting rate. These efforts are specifically targeted at challenging waste types identified at the Savannah River Site (SRS) and Hanford Site. The objectives of current efforts at SIA Radon are to gain insight into vitrification process limits for the cold crucible induction melter (CCIM) technology. Previous demonstration testing has shown that the CCIM offers the potential for dramatic increases in waste loading and waste throughput. However, little information is known regarding operational limits that could affect long-term, efficient CCIM operations. Collaborative work with the Russian Electrotechnical University (ETU) 'LETI' is aimed at advancing CCIM process monitoring, process control and design. The goal is to further mature the CCIM technology and to establish it as a viable HLW vitrification technology. The greater than two year effort conducted with the International Radioecology Laboratory in the Ukraine recently completed. The objectives of this study were: to assess the long-term impacts to the environment from radiation exposure in the Chernobyl Exclusion Zone (ChEZ); and to provide information on remediation guidelines and ecological risk assessment within radioactively contaminated territories around the Chernobyl Nuclear Power Plant (ChNPP) based on the results of long-term field monitoring, analytical measurements, and numerical modeling of soils and groundwater radioactive contamination
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