The Experts below are selected from a list of 84 Experts worldwide ranked by ideXlab platform
Guy Mathieu - One of the best experts on this subject based on the ideXlab platform.
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tracing groundwater flow in the borden aquifer using Krypton 85
Journal of Hydrology, 1992Co-Authors: William M Smethie, Kip D Solomon, Sherry L Schiff, Guy MathieuAbstract:Krypton-85 was measured in air, soil gas, and ground water at the Borden aquifer in Ontario in October 1989. The measured specific activities in air and soil gas were 52.0 ± 2.0 and 53.6 ± 1.8 disintegrations per min (dpm) cm−3 Krypton. These measurements are in excellent agreement with the global atmospheric trend and demonstrate that Krypton-85 enters the water table at the Borden site without a lag in the soil gas reservoir. The Krypton-85 specific activity in five groundwater samples ranged from 44.9 to 9.5 dpm cm−3 corresponding to groundwater ages of 2–17 years with a monotonic decrease in specific activity (increase in age) along the groundwater flow path. Travel times calculated from a two-dimensional steady-state model of groundwater flow agree well with the Krypton-85 ages in the main recharge region of the aquifer where flow is predominantly vertical, but were 30–40% older than the Krypton-85 age downstream of the main recharge area where the flow is mainly horizontal. The effect of dispersion on the distribution of Krypton-85 was determined by modelling the transport of Krypton-85 in the Borden aquifer with a two-dimensional time-dependent advection dispersion model using the steady-state flow field. Agreement between model specific activity and observed specific activity was excellent for samples in the main recharge region, but the model specific activities were 30–50% lower than observed specific activities in the region of horizontal flow. The differences in travel times and Krypton-85 ages and in model Krypton-85 and observed Krypton-85 specific activities are considered to be small given the heterogeneities that exist in the hydraulic conductivity and aquifer geometry and hence in the groundwater flow field. The model simulated Krypton-85 distribution was not sensitive to changes in longitudinal dispersivity and was only weakly sensitive to changes in transverse dispersivity. The geochemical inertness, well-defined source function, and insensitivity to dispersion of Krypton-85 allow estimates of groundwater age to be made in a straightforward manner and measurement of Krypton-85 can significantly enhance the characterization of groundwater flow in many shallow subsurface systems.
Martin Kalinowski - One of the best experts on this subject based on the ideXlab platform.
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update and improvement of the global Krypton 85 emission inventory
Journal of Environmental Radioactivity, 2013Co-Authors: Jochen Ahlswede, Simon Hebel, Ole J Ross, Robert Schoetter, Martin KalinowskiAbstract:Krypton-85 is mainly produced in nuclear reactors by fission of uranium and plutonium and released during chopping and dissolution of spent fuel rods in nuclear reprocessing facilities. As noble gas it is suited as a passive tracer for evaluation of atmospheric transport models. Furthermore, research is ongoing to assess its quality as an indicator for clandestine reprocessing activities. This paper continues previous efforts to compile a comprehensive historic emission inventory for Krypton-85. Reprocessing facilities are the by far largest emitters of Krypton-85. Information on sources and calculations used to derive the annual Krypton-85 emission is provided for all known reprocessing facilities in the world. In addition, the emission characteristics of two plants, Tokai (Japan) and La Hague (France), are analysed in detail using emission data with high temporal resolution. Other types of Krypton-85 sources are power reactors, naval reactors and isotope production facilities. These sources contribute only little or negligible amounts of Krypton-85 compared to the large reprocessing facilities. Taking the decay of Krypton-85 into account, the global atmospheric inventory is estimated to about 5500 PBq at the end of 2009. The correctness if the inventory has been proven by meteorological simulations and its error is assumed to be in the range of a few percent.
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simulation of atmospheric Krypton 85 transport to assess the detectability of clandestine nuclear reprocessing
2010Co-Authors: Ole Ross, Heinke K Schluenzen, Martin KalinowskiAbstract:The results of this study were achieved in the project “Simulation of Atmospheric Noble Gas Concentrations to Assess Sampling Procedures for the Detection of Clandestine Nuclear Reprocessing” (IAEA GER 1643) in the joint programme of IAEA and Federal Government of Germany. In the first year of the project the detectability of additional Krypton-85 sources was investigated using atmospheric transport modelling. Krypton-85 is released into the air during reprocessing of spent nuclear fuel rods. Therefore the Krypton-85 signature can possibly be used for the detection of undeclared plutonium separation. First, the global Krypton-85 background produced by known reprocessing facilities from 1971 until 2006 was simulated with the atmospheric general circulation model ECHAM5 using annual emission data. The model results were evaluated by extensive comparison with measurements performed by the German Federal Office for Radiation Protection. Of particular interest for an assessment of the detectability of unknown sources is the background variability. The variability of concentrations is very high over central Europe, where the large reprocessing plants La Hague and Sellafield are located, and it is very low on the Southern Hemisphere, where no nuclear reprocessing takes place. The analysis of concentration time series on various time scales allows partly a distinction between fluctuations caused by the variability of the sources from variations due to atmospheric dynamics. Furthermore the detection sensitivity to a set of arbitrarily specified source locations is analysed with a Lagrangian particle dispersion model. This, in combination with the location specific background variability, is giving first benchmarks on the capability of using Krypton-85 for IAEA Safeguards based on the Additional Protocols foreseeing environmental sampling.
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conclusions on plutonium separation from atmospheric Krypton 85 measured at various distances from the karlsruhe reprocessing plant
Journal of Environmental Radioactivity, 2004Co-Authors: Martin Kalinowski, Hartmut Sartorius, Wolfgang WeissAbstract:Abstract For wide-area atmospheric monitoring, Krypton-85 is the best indicator for clandestine plutonium separations. The detection and false alarm rates were determined from weekly samples at five different distances from the Karlsruhe reprocessing plant between 1985 and 1988. The detection rate for the separation of 4 kg of plutonium per week was found to be as high as 80–90% at a distance of less than 1 km, 70% at 5 km, 40% at 39 km, and 15% at 130 km. At distances up to 40 km, the false alarm rate is less than 3.5%. On average, the fuel released 28 TBq Krypton-85 per kg plutonium. For weapons-grade plutonium, the Krypton signal would be lower by a factor of 2. Hence, the given percentages correspond to the detection probabilities for the separation of a significant quantity (8 kg) of plutonium per weekly sample under the specific meteorological conditions of the WAK. The minimum separation rates that could have been detected are 2 gram of weapons-grade plutonium per week at a distance of less than 1 km, 40 g/week at 5 km, 200 g/week at 39 km, and 1000 g/week at 130 km.
William M Smethie - One of the best experts on this subject based on the ideXlab platform.
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tracing groundwater flow in the borden aquifer using Krypton 85
Journal of Hydrology, 1992Co-Authors: William M Smethie, Kip D Solomon, Sherry L Schiff, Guy MathieuAbstract:Krypton-85 was measured in air, soil gas, and ground water at the Borden aquifer in Ontario in October 1989. The measured specific activities in air and soil gas were 52.0 ± 2.0 and 53.6 ± 1.8 disintegrations per min (dpm) cm−3 Krypton. These measurements are in excellent agreement with the global atmospheric trend and demonstrate that Krypton-85 enters the water table at the Borden site without a lag in the soil gas reservoir. The Krypton-85 specific activity in five groundwater samples ranged from 44.9 to 9.5 dpm cm−3 corresponding to groundwater ages of 2–17 years with a monotonic decrease in specific activity (increase in age) along the groundwater flow path. Travel times calculated from a two-dimensional steady-state model of groundwater flow agree well with the Krypton-85 ages in the main recharge region of the aquifer where flow is predominantly vertical, but were 30–40% older than the Krypton-85 age downstream of the main recharge area where the flow is mainly horizontal. The effect of dispersion on the distribution of Krypton-85 was determined by modelling the transport of Krypton-85 in the Borden aquifer with a two-dimensional time-dependent advection dispersion model using the steady-state flow field. Agreement between model specific activity and observed specific activity was excellent for samples in the main recharge region, but the model specific activities were 30–50% lower than observed specific activities in the region of horizontal flow. The differences in travel times and Krypton-85 ages and in model Krypton-85 and observed Krypton-85 specific activities are considered to be small given the heterogeneities that exist in the hydraulic conductivity and aquifer geometry and hence in the groundwater flow field. The model simulated Krypton-85 distribution was not sensitive to changes in longitudinal dispersivity and was only weakly sensitive to changes in transverse dispersivity. The geochemical inertness, well-defined source function, and insensitivity to dispersion of Krypton-85 allow estimates of groundwater age to be made in a straightforward manner and measurement of Krypton-85 can significantly enhance the characterization of groundwater flow in many shallow subsurface systems.
Michael Schoeppner - One of the best experts on this subject based on the ideXlab platform.
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Detecting Clandestine Reprocessing Activities in the Middle East
Science & Global Security, 2018Co-Authors: Michael SchoeppnerAbstract:ABSTRACTRemote monitoring of Krypton-85 from undeclared reprocessing of spent nuclear fuel could be part of a fissile material cut-off treaty, could serve as an additional measure for the IAEA safeguards system to monitor compliance with the Non-Proliferation of Nuclear Weapons Treaty, and could be an important verification tool of a reprocessing moratorium or Nuclear Weapon Free Zone in the Middle East or East Asia. Atmospheric transport modelling is applied to determine the area over which Krypton-85 emissions from undeclared reprocessing activities at various levels in the Middle East would still be detectable against the high Krypton-85 background from reprocessing in historical weapon programs in the United States and USSR as well as more recent and ongoing commercial reprocessing in France and the U.K. Analysis of annual wind flow over Israel's Dimona facility, the only operating reprocessing site in the region, suggests that a known reprocessing plant could be monitored with one or a few fixed moni...
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present and future potential of Krypton 85 for the detection of clandestine reprocessing plants for treaty verification
Journal of Environmental Radioactivity, 2016Co-Authors: Michael Schoeppner, Alexander GlaserAbstract:Burnup calculations are applied to determine the amount of Krypton-85 that is produced during the irradiation of nuclear fuel. Since Krypton-85 is most likely released into the atmosphere during reprocessing to separate plutonium, atmospheric transport modeling is used to calculate the worldwide distribution of Krypton-85 concentrations stemming from emissions from declared reprocessing plants. The results are the basis for scenarios in which emissions from clandestine reprocessing facilities have to be detected against various background levels. It is concluded that today's background imposes heavily on the ability to detect small and medium plutonium separation rates; only high separation rates of 1 SQ per week and higher have a chance to be detected with feasible outlay. A fixed network of monitoring stations seems too costly; instead the high number of samples that are required rather calls for mobile sampling procedures, where air samples are collected at random locations over the world and are analyzed in regional laboratories for their Krypton-85 concentration. Further, it is argued that Krypton-85 emissions from declared reprocessing activities have to be significantly lowered to enable a worldwide verification of the absence of even smaller clandestine reprocessing. For each scenario the number of samples that have to be taken for probable detection is calculated.
Alexander Glaser - One of the best experts on this subject based on the ideXlab platform.
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present and future potential of Krypton 85 for the detection of clandestine reprocessing plants for treaty verification
Journal of Environmental Radioactivity, 2016Co-Authors: Michael Schoeppner, Alexander GlaserAbstract:Burnup calculations are applied to determine the amount of Krypton-85 that is produced during the irradiation of nuclear fuel. Since Krypton-85 is most likely released into the atmosphere during reprocessing to separate plutonium, atmospheric transport modeling is used to calculate the worldwide distribution of Krypton-85 concentrations stemming from emissions from declared reprocessing plants. The results are the basis for scenarios in which emissions from clandestine reprocessing facilities have to be detected against various background levels. It is concluded that today's background imposes heavily on the ability to detect small and medium plutonium separation rates; only high separation rates of 1 SQ per week and higher have a chance to be detected with feasible outlay. A fixed network of monitoring stations seems too costly; instead the high number of samples that are required rather calls for mobile sampling procedures, where air samples are collected at random locations over the world and are analyzed in regional laboratories for their Krypton-85 concentration. Further, it is argued that Krypton-85 emissions from declared reprocessing activities have to be significantly lowered to enable a worldwide verification of the absence of even smaller clandestine reprocessing. For each scenario the number of samples that have to be taken for probable detection is calculated.
