scholarly journals STUDY ON UNCERTAINTIES OF RADIONUCLIDE MIGRATION PARAMETER VALUES OBTAINED FROM IN-SITU TRACER TESTS

2004 ◽  
pp. 85-97
Author(s):  
Yuji IJIRI ◽  
Akihito RATA ◽  
Kenichi HOSONO ◽  
Atsushi SAWADA
Keyword(s):  
Tracer Tests ◽  
Radionuclide Migration ◽  
Migration Parameter ◽  
Parameter Values

In-situ mass spectrometry improves the estimation of stream reaeration from gas-tracer tests

2019 ◽  
Vol 655 ◽  
pp. 1062-1070 ◽  
Author(s):  
Julia L.A. Knapp ◽  
Karsten Osenbrück ◽  
Matthias S. Brennwald ◽  
Olaf A. Cirpka
Keyword(s):  
Mass Spectrometry ◽  
Tracer Tests ◽  
Gas Tracer

Assessing in situ Radionuclide Migration from Natural Analog Studies: Response to McKinley and Alexander (1996)

1998 ◽  
Vol 80 (4) ◽  
Author(s):  
Teh-Lung Ku ◽  
Shangde Luo ◽  
Bret W. Leslie ◽  
Douglas E. Hammond
Keyword(s):  
Radionuclide Migration ◽  
Natural Analog

scholarly journals Assessing denitrification in groundwater using natural gradient tracer tests with15N: In situ measurement of a sequential multistep reaction

2004 ◽  
Vol 40 (7) ◽  
Author(s):  
Richard L. Smith ◽  
John Karl Böhlke ◽  
Stephen P. Garabedian ◽  
Kinga M. Revesz ◽  
Tadashi Yoshinari
Keyword(s):  
Tracer Tests ◽  
In Situ Measurement ◽  
Natural Gradient ◽  
Multistep Reaction

Leaching and migration of Np, Pu, and Am from α-doped SON68 HLW glass in contact with dense clay

2006 ◽  
Vol 932 ◽  
Author(s):  
Elie Valcke ◽  
Mireille Gysemans ◽  
Hugo Moors ◽  
Pierre Van Iseghem ◽  
Nicole Godon ◽  
...  
Keyword(s):  
Glass Frit ◽  
High Density ◽  
Radionuclide Migration ◽  
Colloidal Transport ◽  
Boom Clay ◽  
Backfill Materials ◽  
Powdered Glass ◽  
And Migration ◽  
Radionuclide Leaching

ABSTRACTIn the frame of an integrated in situ test on the alteration of the SON68 reference glass in realistic disposal conditions, the leaching of Np, Pu, and Am from α-doped SON68 glass samples and their migration in three clay-based backfill materials at high density was measured. The addition of powdered glass frit to a Ca-bentonite decreased the glass alteration by two orders of magnitude, and resulted in a concomitant decrease of the radionuclide leaching in comparison with dried Boom Clay, which is the more agressive backfill. All actinides were selectively retained in the alteration layer, but the retention degree was lower for Np than for Pu and Am. All backfill materials proved to be efficient barriers against radionuclide migration. For nearly all radionuclides and backfill materials, the migration profile showed a contribution of colloidal transport.

Site Characterization for Field Radionuclide Migration Studies in Climax Granite

1981 ◽  
Vol 6 ◽  
Author(s):  
Dana Isherwood ◽  
Ellen Raber ◽  
Randolph Stone
Keyword(s):  
Flow Model ◽  
Test Site ◽  
Hydraulic Testing ◽  
Nevada Test Site ◽  
Radionuclide Migration ◽  
Critical Question ◽  
Initial Field ◽  
In Situ Conditions ◽  
Fracture Apertures

ABSTRACTRadionuclide migration experiments in fractured granite at the Climax Stock, Nevada Test Site, are needed to compare field and laboratory measured retardation factors to determine whether laboratory studies accurately reflect in situ conditions. Initial field activities have concentrated on hydrological investigations to determine whether the fractures in Climax granite are suitable for migration experiments. A critical question was whether we could isolate a single vertical fracture between two boreholes and establish flow along that fracture from an upper to a lower borehole. Of the ten fractures tested, one fracture would not take water at pressures up to 200 psig for 24 hours. Several fractures were so permeable they accepted water at a rate which exceeded the pumping capacity of the equipment. Other fractures failed to show a connection between the two boreholes. In two fractures, we were able to establish a circulating system with up to 95 percent of the injected water being recovered. Constant pressure injection tests were conducted. Intrinsic permeabilities of 33 and 75 (μm)2 were estimated using a radial nonsteady flow model. These values correspond to effective fracture apertures of 20 and 30 μm respectively. Concurrent with the hydraulic testing activities is a study of the Climax ground-water chemistry. Our analyses show the natural water to be very different in composition from the granite equilibrated water used in laboratory sorption studies. This paper includes the results of the hydrogeological and geochemical investigations, and describes the overall experimental design plans for the radionuclide migration experiments.

scholarly journals Optimization of a micronekton model with acoustic data

2014 ◽  
Vol 72 (5) ◽  
pp. 1399-1412 ◽  
Author(s):  
Patrick Lehodey ◽  
Anna Conchon ◽  
Inna Senina ◽  
Réka Domokos ◽  
Beatriz Calmettes ◽  
...  
Keyword(s):  
Primary Production ◽  
Functional Groups ◽  
Spatial Dynamics ◽  
Likelihood Estimation ◽  
Environmental Forcing ◽  
Acoustic Data ◽  
Population Dynamics Model ◽  
Ocean Ecosystem ◽  
Parameter Values

Abstract In the pelagic foodweb, micronekton at the mid-trophic level (MTL) are one of the lesser known components of the ocean ecosystem despite being a major driver of the spatial dynamics of their predators, of which many are exploited species (e.g. tunas). The Spatial Ecosystem and Population Dynamics Model is one modelling approach that includes a representation of the spatial dynamics of several epi- and mesopelagic MTL functional groups. The dynamics of these groups are driven by physical (temperature and currents) and biogeochemical (primary production, euphotic depth) variables. A key issue to address is the parameterization of the energy transfer from the primary production to these functional groups. We present a method using in situ acoustic data to estimate the parameters with a maximum likelihood estimation approach. A series of twin experiments conducted to test the behaviour of the model suggested that in the ideal case, that is, with an environmental forcing perfectly simulated and biomass estimates directly correlated with the acoustic signal, a minimum of 200 observations over several time steps at the resolution of the model is needed to estimate the parameter values with a minimum error. A transect of acoustic backscatter at 38 kHz collected during scientific cruises north of Hawaii allowed a first illustration of the approach with actual data. A discussion followed regarding the various sources of uncertainties associated with the use of acoustic data in micronekton biomass.

Hydrogeologic investigation of groundwater velocity for matrix and conduit in a karst aquifer

2020 ◽  
Author(s):  
Hyemin Park ◽  
Minjune Yang
Keyword(s):  
Karst Aquifer ◽  
Tracer Tests ◽  
Karst Aquifers ◽  
Total Flow ◽  
Groundwater Velocity ◽  
Cross Sectional ◽  
Matrix Flow ◽  
Flow Through ◽  
Dual Domain

<p>It has been recognized that karst aquifers are a unique hydrogeologic system because of strong heterogeneity originating from their complexity of the karst medium. Most karst aquifers have large ranges of flow distributions due to various types of porosity such as matrix, connected fractures, faults, and conduits developed from dissolution. In this study, we measured groundwater velocities in the Floridan aquifer within the springshed of Silver Springs, FL. Groundwater velocities were measured <em>in situ</em> using passive flux meters (PFMs) and karstic borehole dilution (KBHD). Based on these data and previous tracer tests, we estimated rock matrix and conduit velocities of 0.06 ± 0.02 m/day and 3.05 ± 8.1 m/day. These data were coupled with simple analytical solutions to identify the proportion of the aquifer that contributes most significantly to water flow into the spring with two different modeling scenarios: single domain and dual-domain including matrix and non-matrix zones. The dual-domain scenario suggest that matrix flow contribute approximately 4% of the total flow while non-matrix flow through conduits and fractures contribute approximately 96% of the total flow, even though the non-matrix zones account for only 5.2% of the total aquifer cross-sectional area, within approximately 3 km from the spring outlet (with the upstream capture zone representing approximately 1% of the springshed area (2300 km). The results offer field-measured hydrogeologic data that can be used for active resource management in the springshed and the simple modeling approach presented in this study might be applicable to other springs to estimate the portion of water flows and solute pathways to the spring outlet.</p>

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